Evidence-Based Practiceof Anesthesiology

Evidence-Based Practiceof AnesthesiologySecond Edition

Lee A. Fleisher, MDRobert Dunning Dripps Professor and ChairDepartment of AnesthesiologyProfessor of MedicineUniversity of Pennsylvania School of MedicinePhiladelphia, Pennsylvania

1600 John F. Kennedy Blvd.Ste 1800Philadelphia, PA 19103-2899

EVIDENCE-BASED PRACTICE OF ANESTHESIOLOGY, 2ND EDITION ISBN: 978-1-4160-5996-7

Copyright # 2009, 2004 by Saunders, an imprint of Elsevier Inc.

All rights reserved. No part of this publication may be reproduced or transmitted in any formor by any means, electronic or mechanical, including photocopying, recording, or any informationstorage and retrieval system, without permission in writing from the publisher. Permissions may besought directly from Elsevier’s Rights Department: phone: (þ1) 215 239 3804 (US) or (þ44) 1865843830 (UK); fax: (þ44) 1865 853333; e-mail: healthpermissions@elsevier.com. You may alsocomplete your request on-line via the Elsevier website at http://www.elsevier.com/permissions.

Notice

Knowledge and best practice in this field are constantly changing. As new research andexperience broaden our knowledge, changes in practice, treatment and drug therapy may becomenecessary or appropriate. Readers are advised to check the most current information provided(i) on procedures featured or (ii) by the manufacturer of each product to be administered, to verifythe recommended dose or formula, the method and duration of administration, andcontraindications. It is the responsibility of the practitioner, relying on their own experience andknowledge of the patient, to make diagnoses, to determine dosages and the best treatment foreach individual patient, and to take all appropriate safety precautions. To the fullest extent of thelaw, neither the Publisher nor the Editor assumes any liability for any injury and/or damage topersons or property arising out of or related to any use of the material contained in this book.

The Publisher

Library of Congress Cataloging-in-Publication DataEvidence-based practice of anesthesiology / [edited by] Lee A. Fleisher.-- 2nd ed.

p. ; cm.Includes bibliographical references.ISBN 978-1-4160-5996-7

1. Anesthesiology. 2. Evidence-based medicine. I. Fleisher, Lee A.[DNLM: 1. Anesthesia. 2. Evidence-Based Medicine. WO 200 E928 2009]RD81. E86 2009617.9’6--de22

2008043224

Acquisitions Editor: Natasha AndjelkovicDevelopmental Editor: Isabel TrudeauProject Manager: Bryan HaywardDesign Direction: Karen O’Keefe Owens

Printed in the United States of America

Last digit is the print number: 9 8 7 6 5 4 3 2 1

Dedication

This book is dedicated to my children, Matthew andJessica, for their unconditional love and support, as wellas their constant desire to understand the justification oftheir parents’ decisions (asking for the evidence). In addi-tion, the book is dedicated to the residents of the

University of Pennsylvania Department of Anesthesiologyand Critical Care, who also constantly seek justification inthe form of evidence for the faculty’s and my decisions onhow best to care for our patients.

v

Contributors

Sherif Afifi, MD, FCCM, FCCPAssociate Professor of Anesthesiology & SurgeryChief, Division of Critical CareDirector of Critical Care FellowshipFeinberg School of MedicineNorthwestern UniversityChicago, Illinois

Seth Akst, MD, MBAAssistant ProfessorDepartment of Anesthesiology and Critical Care MedicineGeorge Washington University Medical CenterWashington, DC

James F. Arens, MDChair, Committee of Practice ParametersAmerican Society of AnesthesiologyPark Ridge, Illinois

Valerie A. Arkoosh, MDProfessor of Clinical AnesthesiologyUniversity of Pennsylvania School of MedicinePhiladelphia, Pennsylvania

Barbara Armas, MDClinical Assistant Professor of MedicineRobert Wood Johnson University HospitalNew Brunswick, New Jersey

Michael A. Ashburn, MD, MPHProfessor of Anesthesiology and Critical CareMedicine

University of Pennsylvania School of MedicineDirector of Pain Medicine and Palliative CarePenn Pain Medicine CenterTuttleman Center at Penn Medicine at RittenhousePhiladelphia, Pennsylvania

John G.T. Augoustides, MD, FASEAssistant ProfessorDepartment of Anesthesiology and Critical CareUniversity of Pennsylvania School of MedicinePhiladelphia, Pennsylvania

Michael Aziz, MDAssistant ProfessorDepartment of Anesthesiology and Peri-OperativeMedicine

Oregon Health and Science UniversityPortland, Oregon

Daniel Bainbridge, MD, FRCPCAssistant Professor and TEE DirectorDivision of Cardiac AnaesthesiaDepartment of Anaesthesia and Perioperative MedicineLondon Health Sciences CentreUniversity of Western OntarioLondon, Ontario, Canada

Jane C. Ballantyne, MD, FRCAAssociate Professor of AnesthesiologyChief, Division of Pain MedicineDepartment of Anesthesia and Critical CareMassachusetts General HospitalHarvard UniversityBoston, Massachusetts

Sheila R. Barnett, MDAssociate Professor of AnesthesiologyHarvard Medical SchoolDepartment of Anesthesiology and Critical CareBeth Israel Deaconess Hospital Medical CenterBoston, Massachusetts

Joshua A. Beckman, MD, MSDirector, Cardiovascular Medicine FellowshipBrigham and Women’s HospitalAssistant Professor of MedicineHarvard Medical SchoolBoston, Massachusetts

Yaakov Beilin, MDAssociate Professor of Anesthesiology, and Obstetrics,Gynecology and Reproductive Sciences

Vice-Chair for QualityCo-Director of Obstetric AnesthesiaDepartment of AnesthesiologyThe Mount Sinai School of MedicineNew York, New York

Elliott Bennett-Guerrero, MDAssociate ProfessorDepartment of AnesthesiologyDuke University Medical CenterDurham, North Carolina

Sanjay M. Bhananker, MBBS, MD,DA, FRCAAssistant ProfessorDepartment of AnesthesiologyUniversity of Washington School of MedicineHarborview Medical CenterSeattle, Washington

vii

viii Contributors

T. Andrew Bowdle, MD, PhDProfessor of Anesthesiology and PharmaceuticsChief of the Division of Cardiothoracic AnesthesiologyDepartment of AnesthesiologyUniversity of WashingtonSeattle, Washington

Lynn M. Broadman, MDClinical Professor of AnesthesiologyUniversity of Pittsburgh Medical SchoolChildren’s Hospital of PittsburghPittsburgh, Pennsylvania

Daniel R. Brown, MD, PhDAssistant Professor of AnesthesiologyDepartment of AnesthesiologyMayo Clinic College of MedicineRochester, Minnesota

Robert H. Brown, MD, MPHProfessorDepartment of Anesthesiology, Physiology and RadiologyJohns Hopkins University School of MedicineBaltimore, Maryland

Robert A. Caplan, MDDepartment of AnesthesiologyVirginia Mason Medical CenterSeattle, Washington

Jeffrey L. Carson, MDRichard C. Reynolds Professor of MedicineChief, Division of General Internal MedicineUniversity of Medicine and Dentistry of New JerseyRobert Wood Johnson Medical School

New Brunswick, New Jersey

Maurizio Cereda, MDAssistant ProfessorDepartment of Anesthesiology and Critical CareUniversity of Pennsylvania School of MedicinePhiladelphia, Pennsylvania

Mark A. Chaney, MDAssociate ProfessorDirector of Cardiac AnesthesiaDepartment of Anesthesia and Critical CareUniversity of ChicagoChicago, Illinois

Davy Cheng, MD, MSc, FRCPC, FCAHSProfessor and ChairDepartment of Anaesthesia and Perioperative MedicineLondon Health Sciences Centre and St. Joseph’sHealth Care

University of Western OntarioLondon, Ontario, Canada

Grace L. Chien, MDAssociate ProfessorDepartment of AnesthesiologyOregon Health and Sciences UniversityChief of Anesthesiology ServiceVeterans Affairs Medical CenterPortland, Oregon

Vinod Chinnappa, MBBS, MD, FCARCSIClinical FellowDepartment of AnesthesiaUniversity of TorontoToronto Western HospitalUniversity Health NetworkToronto, Ontario, Canada

Frances Chung, FRCPCProfessorDepartment of AnesthesiaUniversity of TorontoToronto Western HospitalUniversity Health NetworkToronto, Ontario, Canada

Neal H. Cohen, MD, MPH, MSVice Dean for Academic AffairsProfessor of Anesthesia and Perioperative CareUniversity of California, San FranciscoSchool of Medicine

San Francisco, California

Nancy Collop, MDAssociate Professor of MedicineDivision of Pulmonary and CriticalCare Medicine

Director, The Johns Hopkins Sleep Disorders CenterBaltimore, Maryland

Richard T. Connis, PhDChief MethodologistCommittee on Standards and Practice ParametersAmerican Society of AnesthesiologistsPark Ridge, Illinois

Douglas B. Coursin, MDProfessor of Anesthesiology and MedicineUniversity of Wisconsin School of Medicine andPublic Health

Madison, Wisconsin

Stefan G. De Hert, MD, PhDProfessor of AnesthesiologyUniversity of AntwerpVice-ChairmanDepartment of AnesthesiologyUniversity Hospital AntwerpEdegem, Belgium

Contributors ix

Clifford S. Deutschman, MD, MS, FCCMProfessor of Anesthesiology and Critical Careand Surgery

Director, Stavropoulos Sepsis Research ProgramUniversity of Pennsylvania School of MedicinePhiladelphia, Pennsylvania

Karen B. Domino, MD, MPHProfessorDepartment of AnesthesiologyUniversity of Washington School of MedicineUniversity of Washington Medical CenterSeattle, Washington

Richard P. Dutton, MD, MBAAssociate Professor of AnesthesiologyChief, Trauma AnesthesiologyUniversity of Maryland Medical Center,Baltimore, Maryland

R. Blaine Easley, MDAssistant ProfessorDepartment of Anesthesiology and CriticalCare Medicine

Johns Hopkins Medical CenterBaltimore, Maryland

David M. Eckmann, PhD, MDHoratio C. Wood Professor of Anesthesiologyand Critical Care

Associate Professor of BioengineeringUniversity of PennsylvaniaPhiladelphia, Pennsylvania

Nabil Elkassabany, MDClinical Assistant ProfessorDepartment of Anesthesiology and Critical CareUniversity of Pennsylvania School of MedicinePhiladelphia, Pennsylvania

John E. Ellis, MDAdjunct ProfessorDepartment of Anesthesiology and Critical CareUniversity of Pennsylvania School of MedicinePhiladelphia, Pennsylvania

Kristin Engelhard, MD, PhDDepartment of AnesthesiologyJohannes Gutenburg UniversityMainz, Germany

Lucinda L. Everett, MDAssociate ProfessorHarvard Medical SchoolChief, Pediatric AnesthesiaMassachusetts General HospitalBoston, Massachusetts

James Y. Findlay, MBChB, FRCAAssistant Professor of AnesthesiologyConsultant, Anesthesiology and Critical Care MedicineDepartment of AnesthesiologyMayo ClinicRochester, Minnesota

Michael G. Fitzsimons, MD, FCCPInstructor in AnesthesiaFellowship Director, Adult Cardiothoracic AnesthesiologyDivision of Cardiac AnesthesiaDepartment of Anesthesia and Critical CareHarvard Medical SchoolMassachusetts General HospitalBoston, Massachusetts

Lee A. Fleisher, MD, FACC, FAHARobert Dunning Dripps Professor and ChairDepartment of Anesthesiology and Critical CareProfessor of MedicineUniversity of Pennsylvania School of Medicine,Philadelphia, Pennsylvania

Nicole Forster, MDDepartment of AnesthesiologyJohannes Gutenburg UniversityMainz, Germany

Stephen E. Fremes, MDHead, Division of Cardiac SurgerySunnybrook and Women’s College Health Sciences CentreToronto, Ontario, Canada

Alan Gaffney, MBBChRegistrar in AnaestheticsUniversity of DublinDublin, Ireland

Tong J. Gan, MBBS, FRCA, FFARCSIProfessorDepartment of AnesthesiologyDuke University Medical CenterDurham, North Carolina

Santiago Garcia, MDChief Cardiology FellowDivision of Cardiovascular MedicineUniversity of MinnesotaMinneapolis, Minnesota

Adrian W. Gelb, MBChBProfessorDepartment of Anesthesiology and Perioperative CareUniversity of California, San FranciscoSan Francisco, California

x Contributors

Ralph Gertler, MDStaff AnesthesiologistInstitute of Anesthesiology and Intensive CareGerman Heart Centre of the State of Bavaria and theTechnical University Munich

München, Germany

Satyajeet Ghatge, MDConsultant AnesthetistUniversity Hospital of North StaffordshireStoke on Trent, United Kingdom

Barbara S. Gold, MDAssociate ProfessorDepartment of AnesthesiologyUniversity of Minnesota Medical SchoolMinneapolis, Minnesota

Allan Gottschalk, MD, PhDAssociate ProfessorDepartment of Anesthesiology and Critical Care MedicineJohns Hopkins Medical InstitutionsBaltimore, Maryland

Anil Gupta, MD, FRCA, PhDAssociate ProfessorDepartment of Anesthesiology and Intensive CareUniversity HospitalÖrebro, Sweden

Veena Guru, MDResearch FellowDepartment of SurgeryUniversity of Pittsburgh Medical SchoolPittsburgh, Pennsylvania

Ashraf S. Habib, MBBCh, MSc, FRCAAssociate ProfessorDepartment of AnesthesiologyDuke University Medical CenterDurham, North Carolina

Carin A. Hagberg, MDProfessorDepartment of AnesthesiologyDirector of Neuroanesthesia and Advanced AirwayManagement

The University of Texas Medical School at HoustonHouston, Texas

Izumi Harukuni, MDAssistant ProfessorDepartment of Anesthesiology and Perioperative MedicineOregon Health and Science UniversityPortland, Oregon

Laurence M. Hausman, MDClinical Assistant Professor ofAnesthesiology

Mount Sinai School of MedicineNew York, New York

Diane E. Head, MDAssistant ProfessorDepartment of AnesthesiologyUniversity of Wisconsin School of Medicine andPublic Health

Madison, Wisconsin

Robert S. Holzman, MD, FAAPAssociate ProfessorDepartment of AnesthesiaHarvard Medical SchoolBoston Children’s HospitalBoston, Massachusetts

McCallum R. Hoyt, MD, MBAAssistant ProfessorDepartment of AnesthesiaHarvard Medical SchoolBrigham and Women’s HospitalBoston, Massachusetts

William E. Hurford, MDProfessor and ChairDepartment of AnesthesiologyUniversity of Cincinnati AcademicHealth Center

Cincinnati, Ohio

Aaron Joffe, DODepartment of AnesthesiologyUniversity of Wisconsin School of Medicineand Public Health

Madison, Wisconsin

Edmund H. Jooste, MBChBAssistant ProfessorDepartment of AnesthesiologyUniversity of Pittsburgh Medical SchoolChildren’s Hospital of PittsburghPittsburgh, Pennsylvania

Girish P. Joshi, MBBS, MD, FFARCSIProfessor of Anesthesiology andPain Management

Director of Perioperative Medicine andAmbulatory Anesthesia

University of Texas Southwestern Medical CenterDallas, Texas

Contributors xi

Andrea Kurz, MDVice ChairDepartment of Outcomes ResearchCleveland Clinic FoundationProfessor of AnesthesiologyCleveland Clinic Lerner College of MedicineCase Western Reserve UniversityCleveland, Ohio

Martin J. London, MDProfessor of Clinical AnesthesiaUniversity of California, San FranciscoVeterans Affairs Medical CenterSan Francisco, California

Lynette Mark, MDAssociate ProfessorDepartment of Anesthesiology & Critical Care Medicineand Department of Otolaryngology/Head andNeck Surgery

Johns Hopkins UniversityBaltimore, Maryland

Lynne G. Maxwell, MDAssociate Director, Division of General AnesthesiaDepartment of Anesthesiology and CriticalCare Medicine

Children’s Hospital of PhiladelphiaPhiladelphia, Pennsylvania

Edward O. McFalls, MD, PhDProfessor of MedicineDivision of CardiologyVeterans Affairs Medical CenterMinneapolis, Minnesota

Michael L. McGarvey, MDDepartment of NeurologyHospital of the University of PennsylvaniaUniversity of Pennsylvania Medical CenterPhiladelphia, Pennsylvania

Kathryn E. McGoldrick, MDProfessor and ChairDepartment of AnesthesiologyNew York Medical CollegeDirector of AnesthesiologyWestchester Medical CenterValhalla, New York

Christopher T. McKee, DOAttending PhysicianDepartment of AnesthesiologyNationwide Children’s HospitalColumbus, Ohio

R. Yan McRae, MDStaff AnesthesiologistPortland Veterans Affairs Medical CenterAssistant ProfessorDepartment of Anesthesiology and PerioperativeMedicineOregon Health and Science UniversityPortland, Oregon

Steven R. Messé, MDAssistant ProfessorDepartment of NeurologyUniversity of Pennsylvania School of MedicinePhiladelphia, Pennsylvania

Amy L. Miller, MD, PhDFellow, Cardiovascular MedicineBrigham and Women’s HospitalInstructor in MedicineHarvard Medical SchoolBoston, Massachusetts

Marek Mirski, MD, PhDVice-ChairDepartment of Anesthesiology and CriticalCare Medicine

DirectorNeuroscience Critical Care UnitsChiefDivision of NeuroanesthesiologyCo-DirectorJohns Hopkins Comprehensive Stroke CenterAssociate Professor of Anesthesiology andCritical Care Medicine, Neurology, and Neurosurgery

Johns Hopkins Medical InstitutionsBaltimore, Maryland

Vivek Moitra, MDAssistant ProfessorDepartment of AnesthesiologyColumbia University College of Physicians and SurgeonsNew York, New York

Terri G. Monk, MD, MSProfessorDepartment of AnesthesiologyDuke University Health SystemDurham Veterans Affairs Medical CenterDurham, North Carolina

Michael F. Mulroy, MDClinical Associate Professor of AnesthesiologyUniversity of Washington School of MedicineDepartment of AnesthesiologyVirginia Mason Medical CenterSeattle, Washington

xii Contributors

Glenn S. Murphy, MDAssociate ProfessorDepartment of AnesthesiologyNorthwestern UniversityFeinberg School of MedicineChicago, IllinoisDirector of Cardiac AnesthesiaEvanston Northwestern HealthcareEvanston, Illinois

Bradly J. Narr, MDAssociate ProfessorDepartment of AnesthesiologyMayo Clinic College of MedicineRochester, Minnesota

Patrick Neligan, MA, MB, FCARCSIClinical Senior Lecturer in Anaesthesia andIntensive Care

University College HospitalGalway, Ireland

David G. Nickinovich, PhDAmerican Society of AnesthesiologistsPark Ridge, Illinois

Gregory A. Nuttall, MDProfessorDepartment of AnesthesiologyMayo Clinic College of MedicineRochester, Minnesota

E. Andrew Ochroch, MDAssistant ProfessorDepartment of Anesthesiology and Critical CareUniversity of Pennsylvania School of MedicinePhiladelphia, Pennsylvania

Catherine M.N. O’Malley, MBBS, FCARCSIDepartment of AnaesthesiaSt. James’s HospitalDublin, Ireland

Alexander Papangelou, MDInstructorDepartment of Anesthesiology and CriticalCare Medicine

Senior Fellow, Neurosciences Critical Care UnitJohns Hopkins Medical InstitutionsBaltimore, Maryland

Anthony N. Passannante, MDProfessor of AnesthesiologyVice Chair for Clinical OperationsDepartment of AnesthesiologyUniversity of North Carolina at Chapel HillChapel Hill, North Carolina

L. Reuven Pasternak, MD, MPH, MBAChief Executive OfficerInova Fairfax HospitalExecutive Vice President for Academic AffairsInova Health SystemFalls Church, Virginia

Donald H. Penning, MD, MS, FRCPProfessor of Clinical AnesthesiologyDirector, Obstetric AnesthesiaUniversity of Miami Miller School of MedicineJackson Memorial HospitalMiami, Florida

Beverly K. Philip, MDProfessor of AnesthesiaHarvard Medical SchoolFounding Director, Day Surgery UnitBrigham and Women’s HospitalBoston, Massachusetts

HughPlayford,MBBS,FANZCA,FFICANZCAAssistant Professor of AnesthesiaDirector of Cardiac Intensive Care UnitWestmead HospitalNew South Wales, Australia

Catherine C. Price, PhDAssistant ProfessorDepartments of Clinical and Health Psychologyand Anesthesiology

University of FloridaGainesville, Florida

George Pyrgos, MDProfessorDepartment of Anesthesiology and CriticalCare Medicine, Department of Medicine, andDepartment of Radiology

Johns Hopkins Medical InstitutionsBaltimore, Maryland

Jeffrey M. Richman, MDAssistant ProfessorDepartment of Anesthesiology and Critical CareMedicine

Johns Hopkins UniversityBaltimore, Maryland

Hynek Riha, MD, DEAAClinical Assistant ProfesorDepartment of Anesthesiology and IntensiveCare Medicine

Institute for Clinical and Experimental MedicineDepartment of Cardiovascular and TransplantationAnesthesiology and Intensive Care Medicine

Postgraduate Medical SchoolPrague, Czech Republic

Contributors xiii

Stephen T. Robinson, MDAssociate Professor of Anesthesiology and PerioperativeMedicine

Oregon Health and Sciences UniversityPortland, Oregon

Anthony M. Roche, MBChB,FRCA, MMedDepartment of AnesthesiologyDuke University Medical CenterDurham, North Carolina

Peter Rock, MD, MBAMartin Helrich Professor and ChairDepartment of AnesthesiologyUniversity of Maryland School of MedicineBaltimore, Maryland

Stanley Rosenbaum, MA, MDProfessor of AnesthesiologyInternal Medicine and SurgeryDirector, Section of Perioperative and Adult AnesthesiaVice-Chair for Academic AffairsDepartment of AnesthesiologyYale University School of MedicineNew Haven, Connecticut

Meg A. Rosenblatt, MDAssociate Professor of AnesthesiologyMount Sinai School of MedicineNew York UniversityNew York, New York

Marc A. Rozner, PhD, MDProfessor of Anesthesiology and Perioperative MedicineProfessor of CardiologyThe University of Texas MD Anderson Cancer CenterAdjunct Assistant Professor of Integrative Biology andPharmacology

University of Texas Health Science Center at HoustonHouston, Texas

Charles Marc Samama, MD, PhD, FCCPProfessor and ChairDepartment of Anaesthesiology and Intensive CareHotel Dieu University HospitalParis, France

Rolf A. Schlichter, MDAssistant Professor of Clinical AnesthesiologyUniversity of Pennsylvania School of MedicinePhiladelphia, Pennsylvania

B. Scott Segal, MDVice-Chairman, Residency EducationDepartment of Anesthesiology, Perioperative andPain Medicine

Brigham and Women’s HospitalBoston, Massachusetts

Douglas C. Shook, MDProgram Director, Cardiothoracic Anesthesia FellowshipDepartment of Anesthesiology, Perioperative andPain Medicine

Brigham and Women’s HospitalHarvard Medical SchoolBoston, Massachusetts

Ashish C. Sinha, MD, PhDAssistant Professor of Anesthesiology andCritical Care

Assistant Professor of Otorhinolaryngology andHead and Neck Surgery

University of Pennsylvania School of MedicinePhiladelphia, Pennsylvania

Robert N. Sladen, MBChB, MRCP(UK),FRCP(C), FCCMProfessor and Vice-ChairDepartment of AnesthesiologyCollege of Physicians and Surgeons of Columbia UniversityNew York, New York

Clinton S. Steffey, MDDepartment of AnesthesiologyState University of New YorkDownstate Medical CenterBrooklyn, New York

Tracey L. Stierer, MDAssociate Professor and Medical Director, Johns HopkinsOutpatient Surgical Services

Department of Anesthesiology and Critical CareMedicine

Johns Hopkins UniversityBaltimore, Maryland

Wyndam Strodtbeck, MDDepartment of AnesthesiologyVirginia Mason Medical CenterSeattle, Washington

Rebecca S. Twersky, MD, MPHProfessor and Vice Chair for ResearchDepartment of AnesthesiologyStatic University of New York DownstateMedical Center

Medical DirectorAmbulatory Surgery UnitLong Island College HospitalBrooklyn, New York

Michael K. Urban, MD, PhDAttending AnesthesiologistHospital for Special SurgeryClinical Associate Professor of AnesthesiologyWeil Medical College of Cornell UniversityNew York, New York

xiv Contributors

Jeffery S. Vender, MDProfessor and Associate ChairDepartment of AnesthesiologyNorthwestern University’s Feinberg School ofMedicine

Evanston, Illinois

Charles B. Watson, MD, FCCMChair, Department of AnesthesiaDeputy Surgeon-in-ChiefBridgeport HospitalYale-New Haven Health SystemBridgeport, Connecticut

James F. Weller, MDStaff AnesthesiologistBethesda North HospitalCincinnati, Ohio

David Wlody, MDInterim Chief Medical Officer and Vice President forMedical Affairs

Medical Director of Perioperative ServicesChairman, Department of AnesthesiologyLong Island College HospitalProfessor of Clinical AnesthesiologyVice Chair for Clinical Affairs and DirectorObstetric AnesthesiaState University of New York DownstateMedical Center

Brooklyn, New York

Christopher L. Wu, MDAssociate ProfessorDepartment of Anesthesiology and Critical Care MedicineJohns Hopkins UniversityBaltimore, Maryland

Foreword to the First Edition

This book is just what I want to read, and it appears justwhen I want to read it. When I look at the outline of ques-tions and topics that Dr. Fleisher chose to present, it isobvious that those are the very questions I wantanswered; at least one of those questions seems to nag atme every day. Rather than just presenting the reader witha problem and laying out the evidence, then leaving thereader in a dilemma of having to make the choice, theauthors state the actions they would take and explainwhy. This in no way restricts the readers, however; it justgives them an idea of what the experts in the field woulddo in a given situation. It is clear that Dr. Fleisher selectedthe authors carefully to have a balanced presentation bythe experts in their fields. He did an outstanding job ofediting this book (I am, of course, biased because he ismy coeditor on Essence of Anesthesia Practice, and I knowthe great work he did on that book).

An example of why I think this is such an outstandingwork is the chapter “Should a Child with Respiratory TractInfection Undergo Elective Surgery?” Drs. Easley andMaxwell not only introduce the problem but also give theevidence that proceeding immediately with surgeryincreases risk. They present the evidence that delaying sur-gery may decrease risk, and, rather than leave the reader in

the lurch, conclude that they would delay surgery for 2 to4 weeks in patients with upper respiratory infection andsymptoms and for 4 to 6 weeks in those with acute lowerrespiratory infection. They state clearly that this is theiropinion and that the existing evidence is not conclusiveenough to be definitive. They then offer the references ifone wants to pursue the question in greater detail.

This book is a great educational tool for the privatepractitioner who wants to know what the experts inthe field would do in a given situation. It is also a greatbook for the resident and faculty member who can learnhow to handle a wide range of important issues, such ashow to handle perioperative hypothermia, whether thechoice of muscle relaxant affects outcome, what to do toprevent peripheral nerve injuries, or whether patients withobstructive sleep apnea should be admitted to the ICU.

I intend to buy two copies of this book—one to keep athome and use to prepare for the next day, and one to keepat work. I plan on relying heavily on this book for teach-ing in the operating room. I think it is a superb additionto our educational armamentarium and hope you enjoyit as much as I did.

Michael F. Roizen, MD

xv

Preface

It has been 5 years since the publication of the firstedition of Evidence-Based Practice of Anesthesiology. I amindeed fortunate to collaborate with my publisher atElsevier, Natasha Andjelkovic, who, when I initially pro-posed this idea to Elsevier, had the foresight to recognizethat this approach to the practice of medicine had becomecritical with respect to clinical care and education. I wasextremely pleased that many practitioners, especially resi-dents, found useful the approach taken to critical ques-tions in the first edition. In editing the second edition, Imaintained the approach and format of the earlier editionand updated important topics with ongoing controversyand added many new topics for which there is increasingevidence on how best to practice. It is my hope that thefield of anesthesiology and perioperative medicine will

continue to grow with increasing high-quality investiga-tions, particularly randomized trials, to expand our evi-dence base and help practitioners provide the highestquality of care.

I am indebted to several people who were critical in thepublication of the second edition of Evidence-Based Practiceof Anesthesiology. I would like to particularly acknowledgemy executive assistant, Eileen O’Shaughnessy, who keptthe authors and myself on track and assisted with theediting of many chapters. In addition to my publisher,I would also like to thank Marla Sussman, our develop-mental editor. I hope this book will provide the answersto many of your daily anesthesia questions.

Lee A. Fleisher, MD

xvii

1

Evidence-Based PracticeParameters—The AmericanSociety of AnesthesiologistsApproach

David G. Nickinovich, PhD; Richard T. Connis, PhD; Robert A. Caplan,MD; and James F. Arens, MD

The American Society of Anesthesiologists (ASA) con-tinues to improve and refine its evidence-based approachto the development of practice parameters. The intentionof ASA practice parameters is to enhance and promotethe safety of anesthetic practice and provide guidance ordirection for the diagnosis, management, and treatmentof clinical problems. Specifically, ASA evidence-basedpractice parameters consist of a “broad body of docu-ments developed on the basis of a systematic and standar-dized approach to the collection, assessment, analysisand reporting of: (1) scientific literature, (2) expert opin-ion, (3) surveys of ASA members, (4) feasibility data and(5) open forum commentary.”1 Evidence-based practiceparameters may take the form of standards, guidelines,or advisories.

Before 1991, ASA practice parameters were consensus-based documents, consisting primarily of practice stan-dards. These practice standards focused on simple aspectsof patient care and applied to virtually all relevant anes-thetic situations, as reflected in the ASA Standards for BasicAnesthetic Monitoring.2 The dissemination of these stan-dards soon positioned the ASA and the Anesthesia PatientSafety Foundation of the ASA at the forefront of medicalpractice by demonstrating the benefits of a proactiveapproach to patient safety.

However, many aspects of clinical practice could notbe adequately covered by the relatively limited and pre-scriptive recommendations of practice standards. Whenbroader and more flexible clinical recommendations wereneeded, the ASA developed and published practice guide-lines. Initially, practice guidelines were developed on thebasis of evidence generated by the same methodologyused in the development of practice standards at the time,namely the consensus of experts.

Recognizing that a more extensive and elaborate meth-odology was needed to evaluate the increasing breadthand complexity of issues addressed by practice guide-lines, the ASA Committee on Standards and Practice Para-meters (Committee) determined that the systematicevaluation of scientific evidence was necessary in addition

to expert opinion. Consequently, in 1991, the ASA adoptedan evidence-based model for the evaluation of scientific lit-erature similar to that in use by the Agency for Health CarePolicy and Research (now the Agency for HealthcareResearch and Quality [AHRQ]). Combining a systematicsynthesis of the literature with expert opinion, ASA pub-lished the first two evidence-based practice guidelines in1993.3,4 In developing these guidelines and recognizingthe unique properties of the anesthesia literature and thepractice of anesthesiology, the Committee realized thatfurther changes in the methodology used were needed.Over the next few years, a multidimensional approach toguideline development evolved that contained four criticalcomponents: (1) a rigorous review and evaluation of allavailable published scientific evidence, (2) meta-analyticassessment of controlled clinical studies, (3) statisticalassessment of expert and practitioner opinion obtained byformally developed surveys, and (4) informal evaluationof opinions obtained from invited and public commentary.

ORGANIZATIONAL CONTEXT

The ASA evidence-based practice parameter process typi-cally begins with the Committee identifying an issue orclinical problem and appointing a task force of 8 to 12anesthesiologists who are recognized experts on the issueor clinical problem and who therefore are able to advisethe Committee on the need for a practice parameter. Taskforce members are carefully chosen to provide a balancebetween private practice and academia, and to ensure rep-resentation across major geographic areas of the UnitedStates. Non-anesthesiologists may also be appointed to atask force when the Committee has determined that suchan appointment is appropriate (e.g., the appointment ofa radiologist to the magnetic resonance imaging [MRI]task force).

If the task force determines that an evidence-basedpractice parameter is needed, it begins the process ofdefining goals and objectives within the mandate of the

3

Table 1-1 Sources of Evidence for PracticeParameters

Source of Evidence Type of Evidence

Randomized controlledtrials

Comparative statistics

Nonrandomizedprospective studies

Comparative statistics

Controlled observationalstudies

Correlation/regression

Retrospective comparativestudies

Comparative statistics

Uncontrolled observationalstudies

Correlation/regression/descriptive statistics

Case reports No statistical dataConsultants Survey findings/expert opinionASA members Survey findings/opinionInvited sources Expert opinionOpen forum commentary Public opinionInternet commentary Public opinion

4 Section I INTRODUCTION

Committee. In addition, it identifies approximately 75 to150 peer-review consultants to serve as an external sourceof opinion, practical knowledge, and expertise. Consul-tants typically are recognized experts in the subject matterand, similar to task force members, represent a balance ofpractice settings and geographic locations. On occasion,individuals from non-anesthesia medical specialties ororganizations are selected as consultants.

To begin development of an evidence-based practiceparameter, a conceptual survey of the task force is con-ducted to identify target conditions, patient or clinical pre-sentations, providers, interventions, practice settings, andother characteristics that help define or clarify the param-eter. Members of the task force then collectively developa list of evidence linkages based on their responses tothis conceptual survey. These evidence linkages representstatements of explicit relationships between particularaspects of anesthetic or clinical care and desired outcomes.The linkages form the foundation on which evidence iscollected and organized, thereby providing the structurewithin which recommendations and advice are formu-lated. When possible and appropriate, evidence linkagesare designed to describe comparative relationships betweeninterventions and outcomes. For example, the linkage state-ment “spinal opioids versus parenteral opioids improvematernal analgesia for labor” identifies a specific interven-tion (spinal opioids), a comparison intervention (parenteralopioids), and a specific clinical outcome (maternal analge-sia) thought to be affected by the intervention. Once all ofthe evidence linkages for the parameter are specified, thetask force then begins the process of collecting evidence.

SOURCES OF EVIDENCE FOR PRACTICEPARAMETERS

The ASA evidence-based process begins with the assump-tion that there is a sufficient body of scientific literatureto produce evidence-based guidelines and clinical recom-mendations. Table 1-1 shows sources of information col-lected by a task force. The accumulated evidence willdetermine whether the document is either a guideline oran advisory. Three major sources of evidence are con-sidered: (1) descriptive summary data from the literature(e.g., means, ranges, sensitivity/specificity), (2) consen-sus-based information obtained from formal surveys,and (3) when sufficient numbers of randomized controlledstudies are available, meta-analytic findings.

The Literature Search

The initial literature search includes a computerizedsearch of the National Library of Medicine and other largereference sources when applicable, and usually yields2000 to 5000 citations for each practice parameter. Manualsearches are also conducted, with supplemental referencessupplied by members of the task force and consultants.

In the selection of published studies, three conditionsmust be met. First, the study must address one or more ofthe evidence linkages being considered. Second, the studymust report an anesthetic or clinical outcome or set of find-ings that can be tallied or quantified, thereby eliminating

reports that contain only opinion (e.g., editorials, newsreports). Third, the study must be an original investigationor report. Thus, review articles, books or book chapters,and manuscripts that report findings from previous publi-cations are not used as a source of evidence. After the ini-tial electronic review, letters, editorials, commentaries,and other literature with no original data are also removedfrom consideration. Typically, 1000 to 2500 articles remainthat are suitable for library retrieval and further review.

Evaluating and Summarizing the Literature

The literature review focuses on evaluating studies thatdirectly address an evidence linkage. When a studyreports an outcome relevant to a given practice parameter,the findings related to that outcome are initially classifiedas directional evidence. Directional evidence refers to adesignation of the extent to which beneficial or harmfulclinical outcomes were found to be associated with a par-ticular intervention. Each reported outcome is numericallyclassified as 1 (beneficial), �1 (harmful), or 0 (neutral).These values are then averaged across all studies to obtainan aggregate directional assessment of support or refuta-tion. Although this aggregated directional assessment isnot intended to provide a statistical finding, it nonethelessdoes provide a useful general indication of the positioningof a particular intervention on a continuum of clinicalbenefit and harm. Moreover, a directional finding maysuggest that a one-tailed relationship exists between aclinical intervention and an outcome of interest, and itmay justify proceeding with a statistical evaluation usingmeta-analysis when sufficient numbers of controlled stud-ies are available.

All relevant articles, regardless of study design, are con-sidered and evaluated during the development of an ASAevidence-based practice parameter. Although randomizedprospectively controlled trials usually provide the strong-est evidence, findings from studies using other research

Chapter 1 Evidence-Based Practice Parameters—The American Society of Anesthesiologists Approach 5

designs also provide critical information. For example, anonrandomized comparative study may provide evidencefor the differential benefits or risks of selected inter-ventions. Observational studies may report frequency orincidence data that can indicate the scope of a problem,event, or condition or may report correlational findingssuggesting associations among clinical interventions andoutcomes. In addition, case reports may describe adverseevents that are not normally reported in controlled studiesand that can be the source of important cautionary nota-tions within a recommendation or advisory. Case reportsmay also be the first indication that a new drug or tech-nique is associated with previously unrecognized benefitor unwanted side effects.

One of the strengths of the ASA protocol for devel-oping evidence-based practice parameters is that the pri-mary search and evaluation of the literature is jointlyconducted by the methodologists and clinicians who serveas members of the task force. Consequently, the researchdesign and statistical aspects, as well as the clinical andpractical significance of a study, are appropriately andthoroughly evaluated. In evaluating this protocol, formalreliability testing among task forcemembers andmethodol-ogists is conducted. Interobserver agreement for researchdesign, type of analysis, linkage assignment, and studyinclusion is calculated using both two-rater agreementpairs (Kappa) and multirater chance-corrected agreement(Sav) values.5,6 These values are reported in the final pub-lished document.

Evaluating and Summarizing ConsensusOpinion

Literature-based scientific evidence is a crucial componentof the process of evidence-based practice parameter devel-opment, but the literature is never the sole source of evi-dence in the development of evidence-based practiceparameters. The task force always supplements scientificfindings with the practical knowledge and opinions ofexpert consultants. The consultants participate in formalsurveys regarding conceptualization, application, and fea-sibility issues, and they also review and comment on theinitial draft report of the task force. Opinion surveys ofthe ASA membership are also conducted to obtain addi-tional consensus-based information used in the final devel-opment of an evidence-based practice parameter. Theevidence obtained from surveys of consultants and ASAmembers represents a valuable and quantifiable source ofevidence, critical to formulation of effective and usefulpractice parameters.

In addition to survey information and commentaryobtained from consultants and practitioners, the task forcecontinually attempts to maximize the amount of consensus-based information available by obtaining opinions froma broader range of sources. These sources include com-ments made by readers of a Web posting of a draft ofthe practice parameter (www.asahq.org) and commentsfrom attendees of one or more public forums scheduledduring major national meetings. After collection and anal-ysis of all scientific and consensus-based information,the draft document is further revised and additional

commentary or opinion is solicited from invited sources,such as the ASA board of directors and presidents ofASA component societies.

Meta-Analysis

When sufficient numbers of controlled studies are foundaddressing a particular evidence linkage, formal meta-analysis for each specific outcome is conducted. For studiescontaining continuous data, either general variance-basedmethods or combined probability tests are used. Whenstudies report dichotomous outcomes, an odds-ratio proce-dure is applied. In summarizing findings, an acceptablesignificance level typically is set at p < 0.01 (one-tailed)and effect size estimates are determined.

Reported findings in the anesthesia literature often usecommon outcome measures, thereby enhancing the like-lihood that aggregated (i.e., pooled) studies will be homo-geneous. Because homogeneity is generally expected, afixed-effects meta-analytic model is used for the initialanalysis. If the pooled studies for an evidence linkageare subsequently found to be heterogeneous, a random-effects analysis is performed, and possible reasons forthe heterogeneous findings are explored. These heteroge-neous findings are reported and discussed as part of theliterature summary for an evidence linkage.

Whenever possible, more than one test is used so that amore complete statistical profile of the evidence linkagecan be evaluated. For example, when a set of studiesallows for more than one meta-analysis (e.g., using bothcontinuous and dichotomous findings), separate meta-analyses are conducted and there must be agreementbetween the separate findings for the results of the ana-lysis to be considered conclusive. Additionally, theseanalyses should be in agreement with the directionalevaluation of the literature and with consensus opinionbefore an unequivocal supportive recommendation isoffered. If disagreements occur, they are fully reportedin the summary of evidence and usually acknowledgedin caveats or notations following the recommendationfor the evidence linkage.

GUIDELINE OR ADVISORY DETERMINATION

For an evidence-based practice parameter to be consid-ered a guideline, all three sources of evidence (directionalevidence from the literature, supporting agreement fromthe consultants and ASA members, and meta-analyticsupport) must be present. If, given the nature of the topic,sufficient controlled studies are not available, an evidence-based practice advisory is formulated to assist practi-tioners in clinical decision making and matters of patientsafety.

The evidence-based practice advisory is a recent inno-vation developed by the Committee and authorized bythe ASA in 1998 in response to the increasing need forexpansion of the evidence-based process to areas whererandomized controlled trials are sparse or nonexistent.This innovation allowed the ASA tremendous flexibilityin applying the evidence-based process to a broader scopeof topics.

http://www.asahq.org

6 Section I INTRODUCTION

The evidence-based protocol for a practice advisory isidentical to that used in the creation of evidence-basedpractice guidelines. A systematic literature search andevaluation of the literature are formally conducted. For-mal survey information is obtained from consultants anda sample of the ASA membership, as well as informalinput from public posting of draft copies of an advisoryon the ASA website, open forum presentations, and otherinvited and public sources.

The available evidence is then synthesized, and a practiceadvisory document is prepared. The intent is to produce areport that summarizes the current state of the literature,characterizes the current spectrum of clinical opinion, andprovides interpretive commentary from the task force.

THE FINAL PRODUCT

A typical practice guideline or advisory requires approxi-mately 2 years for completion at a cost of $200,000 to$300,000. Periodic updates occur 7 to 10 years after publi-cation, unless circumstances require an earlier update.These documents are published in Anesthesiology and areavailable on the journal’s website (www.anesthesiology.org), as well as on the ASA website (www.asahq.org).Supporting material is also available on the journal’swebsite or can be requested from the ASA.

Since adopting the evidence-based model in 1991, theASA has developed and approved 13 evidence-basedpractice guidelines, 6 guideline updates, and 6 evidence-based practice advisories. Currently, no evidence-basedpractice standards are planned.

ASA evidence-based practice guidelines and advisoriesare presented in a format that emphasizes the clinicaluse of the recommendations/advice for the practitioner.Anesthesiologists and other anesthesia care providers aregenerally interested in easily accessible, specific recom-mendations/advice about how to provide optimal careto their patients. Detailed rationales or descriptions oftechniques, exhaustive critiques of the literature, or elabo-rate cost-benefit analyses are usually of secondary con-cern. The ASA has elected to provide documents that arebrief and succinct, with supportive information availablein summary form within the guideline or advisory, in anappendix, at the ASA website, or by request.

The general structure of ASA practice guidelines andadvisories consists of an introductory section, a guide-lines/advisory section, and supporting information (e.g.,tables, figures, or appendices). The introductory sectioncontains the ASA definition of practice guidelines oradvisories, followed by a discussion of the focus, applica-tion, and methodology used in the guideline/advisorydevelopment process. The guidelines or advisories sectionis serially divided into subsections, each based on a sepa-rate evidence linkage. Each evidence linkage subsection is,in turn, divided into two parts: an evidence summary andrecommendations or advice.

The evidence summary subsection contains a descriptionof the literature, generally including statements concerningthe availability of literature, the strength of evidenceobtained from the literature, and details about particularaspects of the literature necessary for a clear interpretation

as it pertains to the evidence linkage. Consultant andmem-bership survey findings are also summarized, in additionto discussion of other opinion-based information whenwarranted.

Because it is assumed that the intended readers of thedocument are knowledgeable regarding the topic, therecommendations or advisories subsections are brief and tothe point, with explanations added only if required forclarification. Cautionary notations may accompany a rec-ommendation or advisory when deemed necessary bythe task force. Extensive literature critiques are not pre-sented in the main text of the document, but details ofthe literature evaluation, as well as opinion-based data,are included in appendices or are available on request.

The ASA evidence-based practice parameters are dis-tributedworldwide andhave beenwell receivedwithin boththe anesthesia community and allied medical professions.

SUMMARY

Evidence-based practice parameters are important decision-making tools for practitioners, and they are particularlyhelpful in providing guidance in areas of difficult or com-plex practice. They can be instrumental in identifying areasof practice that have not yet been clearly defined. Thesedocuments also serve to improve research in anesthesiol-ogy by (1) identifying areas in need of additional study,(2) providing direction for the development of more effica-cious interventions, and (3) emphasizing the importance ofrobust outcome-based research methods. By recognizingthe value of merging broad-based empirical evidence withopinion and consensus, the ASA has taken a leadershiprole in improving specific areas of clinical practice, patientcare, and safety.

The ASA is committed to the development of practiceguidelines and practice advisories by using an evidence-based process that examines testable relationships betweenspecific clinical interventions and desired outcomes(Table 1-2). This process recognizes that evidence is highlyvariable in quality and may come from many sources,including scientific studies, case reports, expert opinion,and practitioner opinion. By providing a consistent andtransparent framework for collecting evidence and byconsidering its strengths as well as weaknesses, the ASAevidence-based process results in practice parameters thatclinicians regard as scientifically valid and clinicallyapplicable.

Physicians have voiced concern that guidelines andadvisories will be treated as de facto standards, therebyincreasing liability and creating unnecessary restraints onclinical practice. The ASA emphasizes the nonbindingnature of practice guidelines, in particular by definingthem as “recommendations that may be adopted, modi-fied, or rejected according to clinical needs and con-straints.” Because the process of evidence-based guidelineand advisory development places a strong emphasis onconsensus formation and communication throughout thepracticing community, guidelines and advisories will con-tinue to be relied on by anesthesiologists and other practi-tioners in their ongoing efforts to maintain a high qualityof patient care and safety.

http://www.anesthesiology.orghttp://www.anesthesiology.orghttp://www.asahq.org

Table 1-2 Strengths of the ASA Evidence-Based Process

Specific outcome data related to a specific intervention arecollected and evaluated.

A broad literature search from a wide variety of publishedarticles.

Systematic evaluation of evidence from qualitatively differentsources.

Randomized controlled studies used in meta-analyses to evaluatecausal relationships.

Nonrandomized controlled studies to provide supplementalinformation.

Descriptive/incidence literature to provide an indication of thescope of a problem.

Case reports to describe adverse events not normally found incontrolled studies.

Opinion-based evidence to evaluate clinical and practical benefits.Evidence from the literature is directionally summarized to clarify

and formalize evidence linkages and to reduce bias inherentin selective reviews.

Reliance on randomized clinical trials to demonstrate causalrelationships and reduce bias inherent in nonrandomizedstudies or case reports.

General use of identical outcome measures rather than poolingdifferent measures.

Consensus information obtained from both formal (e.g., surveys)and informal (e.g., open forums, Internet commentary) sources.

One-to-one correspondence between evidence linkages andrecommendations.

Brevity in reporting evidence.Simple summary statements of literature findings for each

evidence linkage, thereby avoiding exhaustive literaturereviews or critiques.

Specific clinical recommendations without lengthy discussion ordetailed rationale.

Scientific documentation is provided in appendices or is availableseparately.

Bibliographic information is available separately.Periodic updating to reflect new medications, technologies, or

techniques.

Chapter 1 Evidence-Based Practice Parameters—The American Society of Anesthesiologists Approach 7

REFERENCES

1. American Society of Anesthesiologists: Policy statement on prac-tice parameters. In ASA Standards, Guidelines and Statements, Amer-ican Society of Anesthesiologists, October, 2007: http://www.asahq.org/publicationsAndServices/standards/01.pdf.

2. American Society of Anesthesiologists: Standards for basic anes-thetic monitoring. In ASA Standards, Guidelines and Statements,American Society of Anesthesiologists Publication, 5-6, October 1999.

3. American Society of Anesthesiologists: Practice guidelines for pul-monary artery catheterization. Anesthesiology 1993;78:380-394.

4. American Society of Anesthesiologists: Practice guidelines for man-agement of the difficult airway. Anesthesiology 1993;78:597-602.

5. Sackett GP: Observing behavior volume II: Data collection and analysismethods. Baltimore, University Park Press, 1978, pp. 90-93.

6. O’Connell DL, Dobson AJ: General observer agreement measureson individual subjects and groups of subjects. Biometrics 1984;40:973-983.

http://www.asahq.org/publicationsAndServices/standards/01.pdfhttp://www.asahq.org/publicationsAndServices/standards/01.pdf

2

Does Routine Testing AffectOutcome?

L. Reuven Pasternak, MD, MPH, MBA

Preoperative testing for patients undergoing elective sur-gical procedures is an issue that has received considerableattention during the past decade. This attention is notsurprising because preoperative testing affects virtuallyall of the more than 30 million surgical procedures per-formed each year and is associated with costs that runwell into the billions of dollars. Preoperative testing hasbecome the focus of numerous studies and has also servedas the cause for developing guidelines. The two mostimportant of these are the American College of Cardiol-ogy/American Heart Association (ACC/AHA) recom-mendations1 for cardiac patients undergoing noncardiacsurgery and the more general advisory developed by theAmerican Society of Anesthesiologists (ASA).2

The issue of routine testing as a method of screening fordisease processes precedes the debate over this practice inanesthesiology. In the 1960s it was accepted as commonknowledge in some of the most forward-thinking healthsystems that routine screening for various disease pro-cesses independent of the presence of symptoms or identi-fication of risk factors would reveal potentially seriousmedical issues in their “preclinical” phase and thus allowfor earlier intervention and reduced morbidity and mortal-ity rates. These initiatives were undertaken without thebenefit of any definitive outcomes research and were rap-idly accepted as dogma. Conventional medical educationimparted to medical students and residents (and patients)the concept that more testing was consistent with bettermedical care and may serve as a substitute for the historyand physical examination as an indicator of distress.

The factors associated with this development are asso-ciated with the unique climate of that time. Those factorsincluded a sense of almost infinite opportunity for expan-sion of health care resources and a failure to appreciatehow increasingly complex health technology applied ona mass scale could rapidly deplete health care resources.The lack of appreciation of true risk-benefit analysis andevidence-based research was also a major contributor tothis mindset. The sense that tests carried risk beyond costwas not appreciated, and the failure to link outcomes tointerventions was consistent in almost all areas of medi-cine. At present, three factors have converged to reversethis trend. The first two are the new economic imperativesthat make clear that resources are limited, and the drivefor standardization and guideline development withinand between specialties to ensure better communicationand improved patient care. The ability to affect these

two depends on the third development—the emergenceof evidence-based outcomes studies as the accepted scien-tific foundation for recommendations, ranging from pro-tocols to guidelines and advisories.3-6 Note that thischapter will not address the issue of cardiac testing fornoncardiac surgery.

EVIDENCE

Although quick to be accepted on faith, the cascade of evi-dence against routine testing is still met with grudgingacceptance among professional and lay staff. The centraltenet of the evidence-based approach is the value of anyintervention, even an innocuous test of inherently lowmor-bidity and cost, based on the extent that it can be demon-strated to have a beneficial effect as measured by definedoutcomes. These can be either clinical (e.g., morbidity andmortality) or administrative (e.g., enhanced efficiency orpatient satisfaction). In the absence of such evidence, theintervention should not be undertaken. Where the interven-tion has been standard practice for decades, as has been thecase with preoperative testing, this change can be profoundand unsettling but nonetheless scientifically appropriate.

Olsen and colleagues7 were among the first to addressthis issue in the general medical arena in their study ofmultiphasic screening based on a 1972 study of adults in574 families. Within the general category of chemistrytests that are routinely performed preoperatively, the rateof abnormalities was 1% to 3%, with the exception ofserum glucose at 8%. Within these groups, fewer than15% required any therapy. This study was the harbingerof others that started to reverse the trend to large batteriesof tests for routine health screening.

When focusing more closely on the area of tests asso-ciated with preparation for surgery, the evidence is moreprofound for the lack of an association in outcomes. Whenthe ASA did a literature review on this subject, the natureof the evidence by strict evidence-based criteria wasdeemed to be insufficient to provide recommendationsfor specific tests but did confirm the lack of associatedbenefit with routine testing. Kaplan and colleagues8

addressed the issue of the utility of laboratory tests in aretrospective survey of 2000 patients who had undergoneelective surgical procedures. Of the 2236 tests performedin this group (Table 2-1), 65.6% were done without indica-tion. Of the 96 abnormalities encountered, only 10 were in

11

Table 2-1 Preoperative Screening Battery Tests

Test Normal Not Indicated (NI) Abnormal (AB) NI þ AB NI þ AB and Significant

Prothrombin time (PT) 201 154 2 0 0

Partial thromboplastin time (PTT) 199 154 1 0 0

Platelet count 407 366 3 2 1

Complete blood count (CBC) 61 293 22 2 0

White blood cell count with differential 390 324 2 1 0

Chemistry 6 panel 514 176 41 1 1

Glucose 464 361 25 4 2

TOTAL 2236 1828 96 10 4

Adapted from Kaplan EB et al: JAMA 1985;253:3576.

12 Section II PREOPERATIVE PREPARATION

the group without indication, and of these, only 4 weredeemed to be clinically significant. In all cases, the surgerywas performed without known morbidity. Kitz and col-leagues9 demonstrated how the lack of definitive criteriacan cause considerable variance without altered outcomein virtually identical patient populations. Reporting on anaturally occurring experiment, patients undergoingarthroscopy and laparoscopy were assessed on test order-ing. Performed before mandated outpatient managementof these procedures, the two groups were inpatients andoutpatients, with the decision on status determined bysurgeon and patient preference without difference in clin-ical status. The ordering done by surgeons was substan-tially higher in all categories than by the anesthesia staffwithout difference in outcomes in the two groups (Table 2-2). Narr and colleagues,10 in reviewing the testing rou-tinely done on 3782 healthy (ASA Class 1) patients, foundthat only 160 (4%) had abnormalities, of which 30 couldhave been predicted. None of the abnormalities were ofa clinically significant nature, and all patients proceededsafely to surgery. On this basis, the Mayo Clinic in 1991anticipated the more general trend and deferred all testingon healthy, asymptomatic patients for elective surgicalprocedures. In his study of 4058 standardized tests per-formed by protocol in ambulatory patients, Wyatt and col-leagues11 determined that only 1% were of sufficientimportance to mandate delay or cancellation of surgery.Though not as precise as the studies of Kaplan and col-leagues8 and Kitz and colleagues,9 the appearance of thisitem in the surgical literature brought this concept to theattention of the surgical community.

Table 2-2 Preoperative Screening Battery Tests

ARTHROSCOPY LEVE

Test Outpatient (%) Inpatient (%) Outpatie

X-ray 12 30 24

ECG 11 30 12

Chemistry panel 3 92 0

Adapted from Kitz DS et al: Anesthesiology 1988;69:383.

Within the context of specific tests the evidence is sim-ilarly lacking for an association for testing without indica-tion and improvements in outcome. For example,Charpak and colleagues,12 reporting on the utility of rou-tine chest x-rays, found that of 1101 x-rays ordered on3866 patients, only 51 (5%) had an impact on the surgicalplan and anesthetic management and also that these couldhave been predicted on the basis of the patient’s medicalcondition and anticipated surgery. Similarly, Rucker andcolleagues,13 in their review of 905 surgical admissionsreceiving chest x-rays, found that 368 had no risk factorsand, of these, only 1 had a positive finding that did notaffect surgery. Of the remaining 504 with risk factors,114 (22%) had abnormalities, none of which were new orwhich changed planned surgical or anesthetic manage-ment. Similar findings have been found for urinalysis14

and renal function studies.15

Dzankic and colleagues,16 in their study of geriatricpatients, documented the importance of medical and sur-gical risk as opposed to routine testing. In a retrospectivereview of 544 patients ages 70 and older undergoing elec-tive procedures, the authors found a 6.8% prevalence ofabnormal values, with the highest being for creatinine(12%), hemoglobin (10%), and glucose (7%), which is con-sistent with routine physiologic changes for this age-group. When a multivariate regression analysis was doneto determine risk factors associated with adverse outcome,only ASA status greater than II and risk of surgery (perAHA/ACC classification) were found to be factors thatin themselves had any predictive value in determiningoutcome. Age did not constitute a specific risk factor or

L 1 LAPAROSCOPY LEVEL 2 LAPAROSCOPY

nt (%) Inpatient (%) Outpatient (%) Inpatient (%)

58 0 79

50 2 83

75 2 86

Table 2-3 Effectiveness of a PreoperativeEvaluation Center (PEC)

TestSurgicalService PEC

%Reduction

Number of patients 3576 4313 —

Complete blood count 3417 3395* 17.7

Platelet count 3207 2620* 32.3

PT/PTT 2703 578* 82.3

Urinalysis 2489 309* 89.7

General survey panel 2199 811* 69.4

Electrolytes 1775 739* 65.5

Renal panel 1402 1022* 39.5

Electrocardiograms 2202 1362* 48.7

Chest x-rays 2510 1026* 66.1

TOTAL preoperative tests 21,904 11,862* 45.8

Tests per patient 6.13 2.75* 55.1

*p < 0.001.Adapted from Fischer SP: Anesthesiology 1996;85:196.

Chapter 2 Does Routine Testing Affect Outcome? 13

indication for tests. This finding was consistent with thatof the ASA Task Force, which could find no evidence thatage alone was a risk factor that justified electrocardio-grams (ECGs), chest x-rays, or other studies.

The preponderance of evidence thus has demonstratedthat routine performance of tests is not indicated. This hasbeen brought forward into the guideline development pro-cess1,2 and in some official proceedings from outside of theUnited States aswell.17 Indeed, a study by Schein and collea-gues18 of cataract patients found no utility for any testingregardless of baseline health status when associated withoutcomes from this minimally invasive procedure.

Having established that routine screening is of littlemerit, there is emerging evidence that appropriate screen-ing systems are useful in eliminating this excess. Fischer,19

in a study of patients undergoing elective surgical proce-dures, compared consultations, tests, and cancellations ina prestudy group that had tests and consultations orderedby surgical staff, while the posttest group had tests andconsultations ordered by anesthesia staff based on thepresence of specific clinical conditions in an anesthesia-managed preoperative assessment clinic. The group goingthrough the preoperative screening system had a 55.14%reduction testing (Table 2-3) and associated reductions incancellation were from 1.96% to 0.21%. This reductionwas also matched with a 59.3% reduction in associatedcosts ($188.91 versus $76.82). Pollard and colleagues20

demonstrated a similar reduction in cancellations andtesting in a Veterans Administration hospital.

CONTROVERSIES

The movement toward less testing has created an environ-ment that has opened the issue as to whether preopera-tive assessments are of any value. Clinicians and

administrative staff look at studies such as Schein and col-leagues’18 and come to a conclusion not intended by theseauthors: that the assessment by the anesthesiologist has noinherent value with regard to safety or enhanced outcome.Roizen,21 in his editorial response to these perceptions,notes that the real issue is substituting physician judg-ment for laboratory testing within the preoperative pro-cess, an assertion echoed in the ASA advisory on thissubect.2 The issue is not whether administration of anes-thesia provides a risk to the patient, but whether that riskis modified by tests.

AREAS OF UNCERTAINTY

The issue of testing based on individual clinical symptomsmay be subject to some revision based on emerging tech-nologies. The first is the increasing bundling of tests. Forexample, it had been common in the past that each com-ponent of the routine chemistry panel was individuallyrun and billed, making it necessary to order tests in a dis-criminating fashion. There is an increasing ability to per-form large batteries of tests in a manner that iseconomically efficient. In fact, it is now more expensiveto break apart these panels than to simply run the fullseries. Thus, any need to perform venipuncture for testsmay in fact be a simple test-or-no-test decision with virtu-ally all available values returned from this single decisionpoint. If this is the case, the process for deciding on testsactually becomes a simple one that can be made bylower-level staff who can identify any one of several “trig-gers” to mandate this action.

The larger issue relates to what will be the emergingfield of genomics in preoperative assessment. Based prin-cipally in cardiology research, genetic markers forpatients with a predisposition to events such as perioper-ative arrhythmias have been identified, and the tech-nology is being developed for rapid screening ofindividuals. As this new field expands, there will againbe the pressure to screen and to perhaps let enthusiasmget ahead of evidence-based science in adopting thesenew technologies.

GUIDELINES/AUTHOR’SRECOMMENDATIONS

The recommended guidelines are consistent with those of theASA in its Practice Advisory.2 Testing should only be done forspecific clinical conditions based on the patient’s individual his-tory, nature of surgery, and presenting symptoms. Age alone isnot an indication for any of the tests; specific conditions thatmay be associated with the aging process would have to beidentified. Thus, healthy patients of any age undergoing electivesurgical procedures without coexisting medical conditionshould not require any testing unless the nature of the surgerymight result in major physiologic stress or change for whichbaseline studies are indicated. Further testing is only as perthe specific medical condition of the patient based on an appro-priate review of the patient’s history and examination before theday of surgery.

14 Section II PREOPERATIVE PREPARATION

REFERENCES

1. American College of Cardiology/American Heart AssociationTask Force on Practice Guidelines: ACC/AHA guideline updatefor perioperative cardiovascular evaluation for noncardiac sur-gery—executive summary. Anesth Analg 2002;94:1052-1064.

2. American Society of Anesthesiologists Task Force on Preanesthe-sia Evaluation: Practice Advisory for Preanesthesia Evaluation.Anesthesiology 2002;96(2):485-496.

3. Eisenberg JM: Ten lessons for evidence-based technology assess-ment. JAMA 1999;282(19):1865-1872.

4. Evidence-Based Medicine Working Group: Evidence-based med-icine. JAMA 1992;268(17):2420-2425.

5. Leape LL, Berwick DM, Bates DW: What practices will mostimprove safety? Evidence-based medicine meets patient safety.JAMA 2002;288(4):501-507.

6. Shojania KG, Duncan BW, McDonald KM, Wachter RM: Safe butsound: Patient safety meets evidence-based medicine. JAMA2002;288(4):508-513.

7. Olsen DM, Kane RL, Proctor PH: A controlled trial of multiphasicscreening. N Engl J Med 1976;294(17):925-930.

8. Kaplan EB, Sheiner LB, Boeckmann AJ, Roizen MF, Beal SL,Cohen SN, et al: The usefulness of preoperative laboratoryscreening. JAMA 2002;253(24):3576-3581.

9. Kitz DS, Susarz-Ladden C, Lecky JH: Hospital resources usedfor inpatient and ambulatory surgery. Anesthesiology 1988;69(3):383-386.

10. Narr BJ, Hansen TR, Warner MA: Preoperative laboratory screen-ing in healthy Mayo patients: Cost-effective elimination of testsand unchanged outcomes. Mayo Clin Proc 1991;66:155-159.

11. Wyatt WJ, Reed DN, Apelgran KN: Pitfalls in the role of standar-dized preadmission laboratory screening for ambulatory surgery.Am Surg 1989;55:343-346.

12. Charpak Y, Blery C, Chastang C, Szatan M, Fourgeaux B:Prospective assessment of a protocol for selective ordering of pre-operative chest x-rays. Can J Anaesth 1988;35(3):259-264.

13. Rucker L, Frye E, Staten MA: Usefulness of screening chest roent-genograms in preoperative patients. JAMA 1983;250(3):3209-3211.

14. Lawrence VA, Gafni A, Gross M: The unproven utility of the pre-operative urinalysis: Economic evaluation. J Clin Epidemiol1989;42(12):1185-1192.

15. Novis BK, Roizen MF, Aronson S, Thisted RA: Association of pre-operative risk factors with postoperative acute renal failure.Anesth Analg 1991;78:143-149.

16. Dzankic S, Pastor D, Gonzalez C, Leung JM: The prevalence andpredictive value of abnormal laboratory tests in elderly surgicalpatients. Anesth Analg 2001;93:301-308.

17. Munro J, Booth A, Nicholl J: Routine preoperative testing: A sys-tematic review of the evidence. Health Technol Assessment 1997;1(12):1-63.

18. Schein OD, Katz J, Bass EB, Telsch JM, Lubomski LH, FeldmanMA, et al: The value of routine preoperative medical testingbefore cataract surgery. N Engl J Med 2000;342(3):168-175.

19. Fischer SP: Development and effectiveness of an anesthesia pre-operative evaluation clinic in a teaching hospital. Anesthesiology1996;85(1):196-206.

20. Pollard JB, Zboray AL, Mazze RI: Economic benefits attributed toopening a preoperative evaluation clinic for outpatients. AnesthAnalg 1996;83:407-410.

21. Roizen MF: More preoperative assessment by physicians and lessby laboratory tests. N Engl J Med 2000;342(3):204-205.

3

Is a Preoperative ScreeningClinic Cost-Effective?

Sheila R. Barnett, MD

Each year, between 11 and 30 million dollars are spent onpreoperative testing, including laboratory tests and con-sultations.1,2 Currently, 80% of all surgeries are outpatientor same-day admissions, and this has resulted in thedevelopment of preoperative assessment pathways toaccommodate the outpatient surgical setting.

When evaluating the need or value of a preoperativetesting clinic, it is important to understand the wide rangeof factors involved in the preoperative process—manybeyond the anesthesiologist’s usual realm of practice.Once a patient is scheduled for surgery there are severalsteps that occur; although the particular sequence of stepsfor an individual patient will depend on the individualhealth care institution, some requirements are commonto all systems. For instance, the patient will need a hospi-tal identification number to be booked in the operatingroom (OR) scheduling system and insurance and demo-graphic information verified. The patient’s prior medicalrecord will need to be obtained for the holding area orpreoperative assessment clinic. If testing has been done,the results will need to be collated in the chart for theday of surgery, and, in addition, the surgical history andphysical, consent forms, anesthesiology paperwork, andnursing assessment forms must be in the patient’s chartbefore entering the OR. Additionally, the finished chartshould contain all the paperwork needed for the perioper-ative period—order sheets, requisition forms, prescrip-tions, and so on.

Ideally, a cost-effective preoperative screening clinicwould fulfill these duties efficiently, reducing duplicationof work in other areas of the hospital, and contribute pos-itively to OR efficiency.

OPTIONS

The preoperative screening clinic is one example of a pre-operative assessment alternative; others include the tele-phonic interview, Internet health screen, primary carephysician evaluation, and mail-in health quiz. Frequently,a visit to a preoperative clinic is combined with anothertool such as the health survey, and these results are usedto identify patients requiring laboratory testing or a con-sultation with the anesthesiologist. Since the mid-1990s,preoperative testing clinics have gained in popularity. Asurvey of anesthesiology programs found the presenceof a preoperative testing clinic in 88% of university and

70% of community hospitals in 1998.3 Similar results wereobtained following a survey in Ontario, Canada: 63% of260 hospitals had preoperative clinics.4

EVIDENCE

The Preoperative Process

The evidence supporting the implementation of preopera-tive testing clinics is largely derived from retrospectivestudies, and there are no randomized controlled trialsaddressing the cost of having versus not having a clinic.5,6

Despite this, historical data suggest that the introductionof a system for preoperative testing is associated withincreased patient satisfaction,7 as well as reductions inunnecessary laboratory testing and outside consulta-tions.8-10 More recent data also support a reduction inday-of-surgery cancellations and OR delays and reaffirmthe cost savings gained through reductions in unnecessarylaboratory testing.11-13 From these studies, it is apparentthat local factors such as OR volume and type, patientmix, and even geographic considerations14 will weigh inheavily on the decision to have or use a preoperativeclinic. Evidence in areas of benefit that have been attribu-ted to preoperative clinics will be considered individually(Table 3-1).

The most recent American College of Cardiology/American Heart Association (ACC/AHA) perioperativeguidelines14 provide recommendations for the preopera-tive workup in patients with significant cardiac risk fac-tors undergoing noncardiac surgery. In this group ofindividuals, additional preoperative workup and testingcan be beneficial. In general, patients with known coro-nary disease should receive a careful cardiac baselineassessment; this includes a review of current testingresults and new tests as warranted by the history andphysical. When older than 50 years of age, even asymp-tomatic patients may require careful cardiac evaluation ifthere are associated cardiac risk factors. The advantageof the preoperative testing clinic is the ability of theanesthesiologists to oversee the appropriate testing andconsultations.

Laboratory Testing

Inappropriate laboratory testing is costly. Large-scale pre-operative laboratory testing in healthy individuals leads

15

Table 3-1 Cost Savings

Author, Year Study TypeReduction inLaboratory Testing

Reduction inConsultations

Reduction in Same-DayCancellations

$ Saved perPatient

Fischer, 19968 Retrospective 55.1% Yes 116 (87.9%) 112.09

Pollard, 199625 Retrospective 5 (19.4%)

Starsnic, 199718 Retrospective 28.63% 20.89

Vogt, 19972 Retrospective 72.5% 15.75

Finegan, 200517 Prospectivedouble cohort

Yes 29.00

Tsen, 200210 Retrospective Yes

Ferschel, 200513 Retrospective Yes: 50%

Cantlay, 200624 Retrospective Yes

Hariharan, 200611 Prospective Yes: 52%

Correll, 200612 Retrospective Improved recognition ofmedical problems

16 Section II PREOPERATIVE PREPARATION

to an increase in false-positive results and inappropriateworkups.5,9,15,16 Several studies in healthy patients havedemonstrated that screening laboratory testing rarely pro-vides new information that would not otherwise have beenobtained from a thorough history and physical examina-tion.1,9,16 When compared with outside referral physicians,anesthesiologists order fewer preoperative laboratorytests,17-19 and this may be associated with financial benefit.Starsnic and colleagues18 examined testing patterns in twogroups of patients. Each group had approximately 1500patients; laboratory tests were ordered by either theirsurgeon (group S) or by an anesthesiologist seeing themin the preoperative clinic (group A), although in group Asurgeons were still allowed to order additional tests ifrequired. Except for concurrence on the complete bloodcount, anesthesiologists consistently ordered fewer testscompared with surgeons, resulting in a 28.6% reductionin testing and an estimated cost savings of $20.89 perpatient. In a similar study, Vogt and Henson2 found that72% of tests ordered by surgeons were “not indicated”according to anesthesiologists, and the net cost of unindi-cated preoperative tests was $15.75 per patient. Fischer8

compared a 6-month period before and after the intro-duction of a clinic directed by anesthesiologists andobserved a 59.3% reduction in laboratory testing, or$112.09 per patient. Power and Thackray19 report a 38%reduction in preoperative laboratory testing, leading to anestimated saving of $25.44 per patient in 201 elective ear,nose, and throat (ENT) patients following the introductionof testing guidelines that included a review by an anes-thesiologist. More recently, Finegan and colleagues17 per-formed a prospective double-cohort study. In group 1,testing followed usual practice according to preestablishedsurgery-specific clinical pathway guidelines. In contrast,testing for group 2 was instituted only through the anes-thesiologist attending’s or resident’s recommendation.Group 1 included 507 patients with a mean preoperativelaboratory cost of $124 compared with only $95 for the431 patients in group 2 (p < 0.05). When a subgroup

analysis was performed, the average cost of residents’ordering was $110, similar to group 1, whereas attendingphysicians’ cost averaged $74, approximately $36 less thanresidents (p < 0.05). Although group 2 had slightly morecomplications, these were not related to the preoperativetests. This study supports a reduction in unnecessary labo-ratory testing when directed by anesthesiologists anddemonstrates that education and experience may alsocontribute to laboratory savings.

Despite these positive results, reductions in laboratorytesting cannot all be attributed to preoperative clinicsbecause laboratory testing can be reduced even without apreoperative clinic visit. In one of the few randomized con-trolled trials (RCTs) available on preoperative testing,Schein and colleagues1 looked at preoperative testing pat-terns in cataract surgery patients. They randomized 18,189patients scheduled for cataract surgery into two groups;all patients had a history and physical by a health care pro-vider. The “testing” group received additional routine lab-oratory tests and an ECG. In comparison, the “no-testing”group only had tests ordered if indicated by the historyand physical examination. They found no difference in out-come of patients with or without testing, and both groupshad a similar rate of 31 adverse events per 1000 surgeries.

Thus, despite the dearth of RCTs, the current evidencesupports anesthesiology-directed preoperative laboratorytesting. This practice can result in substantial cost savingand benefit to the patient.20,21 The positive evidence doesnot mean that a preoperative testing clinic is always cost-effective because it may be possible to influence testing pat-terns in the absence of a clinic visit. Savings in preoperativelaboratory screening may be achieved by improved educa-tion of other physicians and the development of clinicalpathways by anesthesiologists for surgical patients.22

Consultations

Cardiology consultations are a frequent source of frustra-tion in preoperative testing and often do not result in

Chapter 3 Is a Preoperative Screening Clinic Cost-Effective? 17

significant alterations in management, but instead maylead to delays, additional cost, and inconvenience to thepatient and hospital. Fischer8 found that the introductionof the preoperative clinic led to a significant reduction inthe number of cardiology, pulmonary, and medical con-sultations. Following the introduction of stringent guide-lines for consultation, Tsen and colleagues10 reduced therate of cardiology consultations in patients undergoingnoncardiac surgery from 1.46% (914 patients) to only0.49% (279 patients) (p < 0.0001), despite an increase inpatient acuity over the 6-year study period. They alsofound that, following the introduction of an ECG educa-tional program, they were able to reduce consultationsfor ECG from 43.6% to 28.5% (p < 0.0001).

These groups were able to demonstrate that throughuse of preoperative testing clinics they were able to reduceconsultations and cancellations and delays in surgicalbookings.8,10 In addition, their data support the develop-ment of guidelines for preoperative assessment and edu-cation for those involved in preoperative assessment.23,24

Defining the “role of the consultant” is important in thepreoperative setting. Unfortunately, many consultationsare vague and do not lead to substantial requirementsfor additional testing or provide new recommendationsfor perioperative care. All consultations should provide acareful assessment of risk, and the success of a consulta-tion is improved when the question is specific. An addi-tional role of the consultant should be to advise onfuture health and additional postoperative strategies toreduce the patient’s future risk, if possible.14

Same-Day Cancellations

One major purported benefit of the preoperative screeningclinic is a reduction in cancellations on the day of surgery.There are several reports from individual institutionsdescribing reduction of OR cancellations following theintroduction of a preoperative testing clinic, although norandomized trials on preadmission testing screeningclinics have been conducted. Correll and colleagues12 col-lected data on more than 5000 patients seen in their preop-erative clinic over a 14-month period. In that time, 680medical issues were identified that required further inves-tigation before surgery; 115 of these issues were new med-ical problems. New problems had a greater possibility ofdelay (10.7%) or cancellation (6.8%) compared with exist-ing problems (0.76% and 1.8%). In a similar study, Ferschland colleagues13 compared preoperative testing statusbetween patients assigned to same-day surgery and gen-eral ORs. Over a 6-month period, 6524 patient charts werereviewed. They found that 8.4% (98 of 1164) of same-daysurgery patients were cancelled if seen in clinic versus16.5% (366 of 2252) of those not seen in clinic (p < 0.001).This was even more dramatic for the general OR patients;they found a cancellation rate of 5.3% for those using clinic(87 of 1631) compared with 13.0% (192 of 1477) in those notusing preoperative clinic. In addition, the preoperativeclinic patients were more likely to go to the OR earlier oron time compared with those in the non-preoperativeclinic group. These data support the findings reported byFischer,8 who was able to demonstrate an 87.9% reductionin OR cancellations from 1.96% (132 of 6722) to 0.21%

(16 of 7485) after the formation of the preoperative clinic.Earlier studies have also supported reductions in bothcancellations and length of stay following the introductionof a preoperative testing clinic. However, these data werecollected at the same time that institutions were changingfrom an inpatient to an ambulatory surgery model, sothe impact of the clinic per se is questionable.25-27

Operating room efficiency can be affected by many fac-tors. Inadequate preoperative preparation can result in ORdelays, and same-day cancellations potentially leave costlygaps in the OR schedule.21 Fischer8 found that 90% ofcancellations occurred just before the patient entered theOR. Fischer8 evaluated all cancellations over a 2-yearperiod and found that, on average, a cancellation resultedin 97 minutes of OR downtime; this was in addition tothe usual 30 minutes of turnover time between cases. How-ever, frequent causes of cancellation, such as alterations inthe surgeon’s schedule, patient’s preference, and ORscheduling limitations (i.e., cases running overtime, emer-gency add-ons), will not be influenced by a preoperativescreening clinic.21 It is conceivable that the preoperativescreening clinic could provide a “bank” of availablepatients for call-up at short notice in the event of a gap inthe OR schedule, but there are no data documenting thesuccess of this approach.

Preoperative Clinic Structure

The implementation of educational programs and thedevelopment of clear guidelines and protocols can resultin improved efficiency in the clinic, as well as improvedcommunication and patient satisfaction. The staffing mod-els of preoperative clinics may be diverse, and clinicsstaffed by anesthesiology attendings, residents, dedicatednurse practitioners, and nurses have been described.7,10,28,29

The structure of a preoperative clinic may present signifi-cant opportunities for cost savings. Cantlay and collea-gues24 described improved outcomes after introducing aclinic with consultant anesthesiologists to evaluate complexvascular patients. Varughese and colleagues28 reportedsignificant financial benefit with the creation of a nursepractitioner–assisted preoperative evaluation clinic. At thishospital, they substituted nurse practitioners for two anes-thesiology attending staff in the preoperative clinic; oneattending remained assigned to the clinic for consultations.The nurse practitioners received training in preoperativeassessment. Following the introduction of the nurse practi-tioners into the clinic, the incidence of complications,preoperative patient time, and patient satisfaction weremonitored at three intervals during a 1-year period. Therewas no change in patient satisfaction, complication rates,or time spent in preoperative clinic. Following the substitu-tion of the nurse practitioners in the clinic, the group wasable to provide two more anesthesiologists to the OR. Theincrease in anesthesiologist availability resulted in signifi-cant increases in margin for the hospital and the group—by increasing billable hours for the physicians and throughthe addition of two new ORs, leading to increased casenumbers. Clearly, the opportunity at this institution wasunique; however, it provides an example of redistributionof resources resulting in a more effective preoperativeclinic.

18 Section II PREOPERATIVE PREPARATION

The Patient

It is possible that the savings of the outpatient preopera-tive clinic may in fact represent cost shifted to the patient.For instance, a visit to the preoperative screening clinicmay require additional time o