Pre-operative Assessment

Copyright © 2005, Duke Internal Medicine Residency Curriculum and DHTS Technology Education

Duke Internal Medicine Residency Curriculum

Pre-operative Assessment

Rami Baddredine, MD (Anticoagulation)Miriam Jacob, MD (Anticoagulation and diabetes)

Karen Joynt, MD (Pulmonary)James Yau, MD (Cardiovascular)

Edited by Amy Shaheen, MD

Copyright © 2005, Duke Internal Medicine Residency Curriculum and DHTS Technology Education Services


Learning Objectives

• At the completion of this presentation, the learner should be able to:– Describe appropriate pre-operative cardiovascular evaluation– Describe appropriate pre-operative pulmonary evaluation– Manage anticoagulation in the peri-operative period– Manage diabetes in the peri-operative period– Locate resources related to the above topics on the internet



Presentation Outline

• Cardiovascular evaluation• Pulmonary evaluation• Management of anticoagulation• Management of diabetes• Online resources• Quiz• References



Cardiovascular Pre-op evaluation



Cardiac Preoperative Evaluation

• Epidemiology– The prevalence of cardiovascular disease increases

with age.– Estimated that the number of people >65 in the US

will increase by 25-35% over next 30 years.– This is the same population in which the most

surgical procedures are performed.– Number of noncardiac surgeries may increase from

6 million per year to 12 million per year; some of which have been associated with significant periop cardiac morbidity and mortality.




• ACC/AHA Guideline on Perioperative Cardiovascular Evaluation for Noncardiac Surgery♥ http://www.acc.org/clinical/guidelines/perio/update/pdf/perio_update.pdf

– First developed by ACC/AHA Task Force on Practice Guidelines in 1996.

– Updated in 2002.– Provides framework for considering cardiac risk in

noncardiac surgeries.– Provides tables and algorithms for quick reference

and decision making.




• Purpose– Not to give “medical clearance”.– Perform an evaluation of the patient’s current

medical status.– Make recommendations concerning the evaluation,

management, and risk of cardiac problems over the entire perioperative period

– No test should be performed unless it will influence patient treatment.

– Must be carefully tailored to the patient and the circumstance.




Need for noncardiac surgery

Urgent or elective emergency

Coronary revascularizationWithin 5 years?

Recent coronary evaluationWithin 2 years?

Recurrence of symptoms

Recent stress test orCoronary angiogram

CLINCAL PREDICTORS(see next set of algorithms)

Operate (OK for surgery)

Unfavorable results

favorable results

YES

YES

YES

NO

NO

NO




• Next step is to evaluate the patient’s risk and the inherent riskiness of the surgery

• Patient’s risk is determined by clinical predictors and functional capacity

• Surgery riskiness is determined by the type and site of surgery

• Once patient’s risk and surgery’s risk are known, additional algorithms can be used to determine the appropriate course of action



Cardiac Preoperative Evaluation: Clinical predictors

Clinical Predictors of Increased Perioperative Cardiovascular Risk

Major Intermediate Low

Unstable coronary synd٭ Mild angina Advanced age

Decompensated CHF Prior MI (hx or ECG) Abnormal ECG †

Significant arrhythmias# Compensated or prior CHF Rhythm other than sinus

Significant valvular dz Diabetes mellitus Low functional capacity

Renal insufficiency History of stroke

Uncontrolled HTN

acute (within 7 days) or recent (7-30 days) MI or class III or IV symptoms٭

#high grade AV block, symptomatic ventricular arrhythmia with underlying heart disease, or SVT with uncontrolled ventricular rate

†LVH, LBBB, ST-T abnormalities



Cardiac Preoperative Evaluation: Functional capacity

• Functional capacity is also an important part of the algorithm and relies on “METs”, or metabolic equivalents, to rate a patient’s functionality

• 1 MET is equivalent to a metabolic rate consuming 3.5 milliliters of oxygen per kg of body weight per minute or 1 kilocalorie per kg of body weight per hour

• In a treadmill test, actually measuring METs requires that the person being tested wear a mask in order to measure his or her oxygen consumption (and the carbon dioxide exhaled)

• However, METs can be estimated as follows:– 1-4 METs: daily activities, walking 1-2 blocks on level ground at 2-3

mph, light housework– 4-10 METs: climbing stairs or hill, jogging short distance, heavy

housework, bowling, dancing, golf, swimming– 10-14 METs: running (at least an 8-minute mile), downhill skiing, rock

climbing, etc.



Cardiac Preoperative Evaluation: surgical riskiness

Cardiac Risk* Stratification for Non-cardiac Surgical Procedures

High (>5%) Intermediate (<5%) Low (<1%)

Emergent major operations,

especially in the elderly

Carotid endarterectomy Endoscopic procedures

Major vascular or peripheral vascular surgery

Head and neck operations Superficial procedures

Prolonged surgery with large fluid shifts or blood loss

Intraperitoneal and intrathoracic operations

Cataract surgery

Orthopedic procedures Breast surgery

Prostate surgery

combined risk of cardiac death and nonfatal myocardial infarction٭




Patient withMAJOR CLINICAL

PREDICTORS

Consider delaying or canceling non-cardiac surgery

Medical management and risk factor modification

Consider coronary angiography

Subsequent care* dictated by findings and treatment results

*subsequent care may include delay or canceling surgery, coronary revascularization followed by non-cardiac surgery, or intensified care.




Patient with INTERMEDIATECLINICAL PREDICTORS

Poor functional capacity(<4 METS)

Noninvasive testing

Mod or excellent (>4 METS)

Intermediatesurgical risk

highsurgical risk

lowsurgical risk

Operate


Subsequent care dictated by findings and treatment results

Low risk

High risk




Patient with NO OR MINORCLINICAL PREDICTORS

Poor functional capacity(<4 METS)

Noninvasive testing

Mod or excellent (>4 METS)

Intermediate or low surgical risk

highsurgical risk

Operate


Subsequent care dictated by findings and treatment results

Low risk

High risk



Pulmonary Pre-op evaluation



Pulmonary evaluation

• Currently no published guidelines are available for the general surgical patient

• Existing literature focuses on:– Evaluation of the lung cancer patient prior to lung resection– Evaluation of risk for post-operative pneumonia

• General guidelines are reportedly forthcoming this year



Evaluation of the lung cancer patient prior to lung resection

• 30,000 lung resections are performed annually• Mortality rate from lung resection surgery is 7-11%• Accurate pulmonary evaluation can predict risk of

operative mortality and help stratify patients in terms of treatment options (Beckles 2003, Datta 2003)



Preoperative evaluation

• Staged, stepwise assessment to evaluate risk of complications (Beckles 2003, Datta 2003), starting with careful history and physical examination and then proceeding to objective testing

• Stage I assessment– Spirometry / DLCO measurement, +/- ABG– If FEV1>80% predicted or >2L, MVV is >55% predicted, and

DLCO is >60% predicted, pt is suitable for resection including pneumonectomy without further evaluation

– If pt does not meet these criteria, proceed to stage II testing• Stage II assessment

– Quantitative V/Q scan or differential lung scan– If predicted postoperative (ppo) FEV1 is >40% predicted and ppo

DLCO is >40% predicted, pt is suitable for resection including pneumonectomy

– If pt does not meet these criteria, proceed to stage III testing



Preoperative evaluation continued

• Stage III assessment– Exercise testing– If VO2 max is greater than 20 mL/kg/min, pt is suitable for

surgery– If VO2 max is less than 10 mL/kg/min (roughly the ability to

walk up one flight of stairs), pt is at greatly increased risk of complications and death from surgery and non-surgical management should be pursued

• Alternative algorithm (Wyser 1999)– If FEV1 or DLCO <80% predicted, proceed directly to

exercise testing• If VO2 max >20, proceed to surgery• If VO2 max 10-20, undergo quantitative V/Q and calculate

ppo values as before



Evaluation of risk for post-operative pneumonia

• Why is post-op PNA important?– Pneumonia is the 3rd most common postop complication

(after UTI, wound infection) (Garibaldi 1981)– Pneumonia occurs in 10-40% of patients in the post-op

period and carries a mortality of 30-46% (Brooks-Brunn 1997)

– 25% of deaths occurring within 6 days of surgery are pulmonary in etiology (Brooks-Brunn 1995)



Risk Assessment for Post-op PNA

• Risk index developed in a sample of 10 VA hospitals using data from the Department of Veterans Affairs National Surgical Quality Improvement Program (NSQIP)

• 160,805 patients in derivation cohort, 1997-1999

• 155,266 patients in validation cohort, 1995-1997

• 2,466 patients developed pneumonia (1.5%), compared with myocardial infarction in only 0.4%– Patients with post-op PNA had a 30-day mortality of 21%,

compared with only 2% of the remaining patients



PNA Predictors

• Most important predictors (Odds Ratios, OR, listed for those predictors with OR for development of PNA of greater than 1.5):

• Type of surgery– AAA, OR=4.29– Thoracic surgery, OR=3.92– Upper abdominal surgery, OR=2.68– Neck surgery, OR=2.30– Neurosurgery, OR=2.14



PNA Predictors, continued

• Age– >80, OR=5.63– 70-79, OR=3.58– 60-69, OR=2.38

• Functional status prior to surgery– Totally dependent, OR=2.83– Partially depentent, OR=1.83

• Weight loss > 10% in last 6 months, OR=1.92• History of COPD, OR=1.72• General anesthesia, OR=1.56• “Impaired sensorium,” OR=1.51



Development of Risk Index

• Predictors were then turned into a scoring system, based on strength of association, to allow prospective grading of post-operative risk

• Scoring system (“risk index”) was then validated on an independent cohort

• Notable study limitations: veteran population, very few women, many comorbidities, no data about PFTs was included, no correction for prophylactic antibiotics was possible



Postoperative PNA Risk Index

Preoperative Risk Factor Point value

Type of surgery

AAA repair 15

Thoracic surgery 14

Upper abdominal surgery 10

Neck surgery 8

Neurosurgery 8

Vascular surgery 3

Age

≥80 years 17

70-79 years 13

60-69 years 9

50-59 years 4

Functional status

Totally dependent 10

Partially dependent 6

Preoperative Risk Factor Point value

Weight loss >10% in past 6 months 7

History of COPD 5

Receipt of general anesthesia 4

Impaired sensorium 4

History of CVA 4

Blood urea nitrogen level

<8 mg/dL 4

22-30 mg/dL 2

≥30 mg/dL 3

Transfusion of > 4 units of blood 3

Emergency surgery 3

Steroid use for chronic condition 3

Current smoker within one year 3

Alcohol intake > 2 drinks/d in past 2 wks 2

From Arozullah et al 2001



Risk Index and Outcomes

Risk Class

1 (0-15 pts)

2 (16-25 pts)

3 (26-40 pts)

4 (41-55 pts)

5 (>55 pts)

Rate of postop PNA

in development

cohort, %

0.24 1.19 4.0 9.4 15.8

Rate of postop PNA in validation

cohort, %

0.24 1.18 4.6 10.8 15.9



Pre-op evaluation of coagulationand

Peri-op management of anticoagulation



Management of bleeding risk

• Management of bleeding risk in the peri-op period requires consideration of risk of bleeding

• Defining the level of hemostatic risk for the proposed surgery is essential

• Low Risk surgery: -nonvital organs are involved -surgical site is exposed -limited degree of surgical dissection -local hemostatic measures are likely to be effective -the site does not have local fibrinolysis



Risk assessment, continued

• Moderate / High risk surgeries– Vital organs are involved, with deep or extensive

dissection – The site is associated with local fibrinolysis (eg,

prostatic surgery, tonsillectomy, oral or nasal surgery) – Local hemostatic measures are ineffective (eg, closed

liver or kidney biopsy) – The surgical procedure or the underlying condition is

expected to induce a hemostatic defect (eg, cardiopulmonary bypass, brain injury, extensive malignancy)

– Bleeding complications are frequent and/or are likely to compromise the surgical result



Pre-op workup

• For low risk surgeries : if the history and physical exam do not suggest bleeding then no more tests are needed

• For high risk surgeries : Hx , Physical , platelet count, PT and PTT must be done

• If Hx/ PE or Coags suggest high risk bleeding then more sophisticated tests should be obtained ( heme consult would not hurt)

• A “ Bleeding Time “ is NOT warranted pre-op because it does not predict severity of bleeding



Patients already on anticoagulation

• Patients might be on prophylactic or treatment anticoagulation preoperatively

• Factors to consider when evaluating risk of bleeding with surgery: Age, comorbidities, type of surgery, anticoagulant regimen/ duration and degree of monitoring



Venous Thromboembolism ( VTE)

• Temporal relation of VTE to surgery is key• Within the first month after DVT patients must receive

both pre and post-op anticoagulation• Between 2-3 months, pre-op anticoagulation is only

needed for high risk patients but post-op anticoagulation is recommended to all patients

• After 3 months, the risk of bleeding is more than the benefit of anticoagulation so only prophylactic pre and post-op anticoag. is recommended



Arterial Thromboembolism (ATE)

• The risk of bleeding is similar pre and post-op in patients with ATE

• Continue anticoagulation preop for all patients• Continue post-op anticoagulation only if the surgery is

minor• High risk ATE patients (Like anticoagulation for prosthetic

valves): a heparin bridge is recommended and restart anticoagulation ASAP post-op



General Recommendations

• Always weigh the risk of thrombosis against risk of bleeding

• Patients on oral AC , allow INR to reach 2 pre-op unless high risk bleeding ( INR< 1.5)

• Bridge with Heparin if high risk re-thrombosis



Peri-op management of diabetes



Diabetes- Preoperative Management

• Why do we care?• Increased risk of pre-operative infection• Increased post-operative cardiovascular morbidity and

mortality• Focus is on cardiopulmonary risk assessment and management

• History• Laboratory Studies




• History• Long term complications of DM (i.e. retinopathy,

nephropathy, neuropathy, CHD, PVD)• Baseline glycemic control (freq of monitoring, average

BS)• Hypoglycemia (frequency, severity, awareness, timing)• Therapy (pharmacologic and non-pharmacologic)• Surgery

• Major vs. Minor surgery • When to stop eating• Duration of procedure

• Type of Anesthetic – epidural vs. general




• Laboratory Studies• Baseline EKG, renal function• Baseline glucose levels

– Use this to assess risk for postoperative wound infections

• In case-control study of post-CABG patients, multivariable analysis found patient with preoperative glucose >200 mg/dL had OR of 10.2 for deep sternal wound infections (independent risk factor)2.




Baseline HbA1c – Not recommendedStudy of cardiothoracic surgeries – pt with sternal

wound infection had mean HbA1c of 8.44 vs. 7.80 in those without infection but was not statistically significant (p=0.09)3

Non-invasive cardiac testing dependent on risk stratification

Preoperative Glycemic Control – Goals• Avoid hyperglycemia and hypoglycemia• No consensus about how “tight” the control must be (there is

data in ICU and post-MI patients not in surgery patients- unsure if this translates)




• Type 2 – Diet modification only– Check BG preoperatively and after

• Type 2 – Oral agents– Discontinue agent on morning of surgery– Supplemental sliding scale insulin

• Type 1 or 2 – Insulin Therapy– For short procedures, continue SQ regimen– 1-2 day before, may switch from long-acting to

intermediate acting insulin– May reduce night time intermediate insulin if pt has

borderline hypoglycemia




• If in AM and lunch will be eaten- convert as follows• Once daily intermediate in AM 2/3 dose• Twice daily ½ total dose as intermediate

• If pt misses lunch as well – less AM insulin• Once daily ½ total dose as intermediate• Twice daily 1/3 total dose as intermediate • Multiple short and intermediate 1/3 total dose as intermediate • Multiple short acting 1/3 pre-meal short-acting • Continuous insulin continue basal infusion, use SSI prn

• Later in the day – less AM insulin and start dextrose containing IVF• Long, complex surgeries – use IV Insulin (less variability in BG than with

SQ regimen), start early in AM, closely monitor electrolytes.

No optimal regimen has been found, based on experience and expert opinion.

No particular regimen has been found to affect morbidity, mortality, or length of stay.



Online resources for further info

• Cardiovascular evaluation– http://www.acc.org/clinical/guidelines/perio/clean/I_definition.

htm

• Pulmonary evaluation– http://www.thoracic.org/

• Management of diabetes– http://www.diabetes.org



Quiz

• Question One:– Question: A 76 year-old man with history of CAD s/p CABG (3 years ago),

HTN, DM2, CVA, CRI, and newly diagnosed lung mass was sent to the cardiology clinic by the surgeon for “cardiac clearance” for resection of the mass. Patient reports that he had been doing well and in his USOH, and the mass was discovered on a recent CXR. What is the most appropriate recommendation for this pt?

• A) Pt will need at least a noninvasive test prior to the surgery• B) Pt may proceed with the surgery without further cardiac evaluation• C) Pt will need a coronary angiogram prior to the surgery• D) The surgery should be delayed until he is on optimal medical regimen

– Answer: B. Pt may proceed with the surgery without further cardiac evaluation. Pt had recent revascularization procedure (within 5 years – CABG 3 years ago), and has not had recurrence of symptoms. Therefore, he can proceed to noncardiac surgery without any further cardiac evaluation. Pt still need to continue medical therapy and postoperative risk stratification and risk factor modification.



Quiz continued

• Question Two:– Question: As the cardiology consult resident, you are seeing a 72 year-old

woman with history of DM2, COPD, and on-going tobacco abuse who was admitted with a fractured pelvis after a fall at home. The patient is a resident at an ALF and fell when she tripped over some furniture. She reports that she has had some difficulty with worsening fatigue and DOE, and she can barely walk across the room because of her symptoms. What is the most appropriate recommendation for this pt awaiting an orthopedic procedure?

• A) Pt will need at least a noninvasive test prior to the surgery• B) Pt may proceed with the surgery without further cardiac evaluation• C) Pt will need a coronary angiogram prior to the surgery• D) The surgery should be delayed until she is on optimal medical regimen and has

stopped smoking– Answer: A. Pt should have at least a noninvasive cardiac evaluation given that

she has at least one intermediate clinical predictor (DM) and poor functional capacity (METS<4). If low risk on the noninvasive test, then she may proceed to the OR; but if high risk, she may need more invasive testing such as coronary angiography.



Quiz continued

• Question Three:– You are asked to evaluate Mr. L, a 65 year old male with known COPD, in pre-

op clinic preceding planned resection for a 2 cm right upper lobe nodule. Which of the following statements is FALSE:

• A) If Mr. L’s FEV1 is 40% predicted, he should undergo quantitative V/Q scanning and possibly exercise testing prior to surgery

• B) If Mr. L’s FEV1 is 50% predicted, he can proceed to surgery without further testing so long as lobectomy is not planned

• C) If Mr. L’s FEV1 is 90% predicted with a normal DLCO and MVV, he can proceed to surgery including lobectomy without further testing

• D) If Mr. L’s FEV1 is 2.2L, but his DLCO is only 40% predicted, he should undergo further testing prior to surgery

– Answer: B – If Mr. L has an FEV1 of 50% predicted, he shouldn’t go directly to surgery – instead, he should undergo quantitative V/Q testing and possibly exercise testing prior to surgery for further risk stratification



Quiz continued

• Question Four:– Question: Which of the following is NOT a significant risk factor for

the development of postoperative pneumonia, based on the VA study outlined above?

• A) Thoracic surgery• B) Age greater than 70• C) History of inhaler use• D) Receipt of general anesthesia

– Answer: C – there is no evidence that a history of inhaler use is directly related to risk for post-op PNA, although COPD has been shown to be a risk factor in various smaller studies.



Quiz continued

• Question Five:– Question: Mr Green is a 69 yo healthy male scheduled to

have CABG in 2 weeks. You are asked to asses his bleeding risk. How would you asses him?

• A) History alone• B) History and physical exam• C) PT/PTT/platelets• D) All of the above

– Answer: D. CABG is a high-risk surgery, so he will need a thorough evaluation prior to the procedure.



Quiz continued

• Question Six:– Question: Mr. Smith is a 68 year old male on Coumadin for a

prosthetic mitral valve. He is scheduled to have an inguinal hernia repair. How would you manage his coumadin pre/post-op?

• A) Stop Coumadin 3 days pre-op, no need for bridge. Restart Coumadin 3 days post-op

• B) Stop Coumadin 3 days preop, bridge with heparin when INR<2.5, restart heparin ASAP post-op, and then restart Coumadin

• C) Continue Coumadin through surgery• D) Stop Coumadin one day prior to surgery and do not resume

until 1-2 weeks post-op– Answer: B. This patient is at high risk for ATE despite the

low-risk nature of the surgery and needs a heparin bridge for his procedure.



• Question Seven:– Question: Ms. Apple is a 28 year old female undergoing

thyroidectomy in one week. Pre-op labs show a PTT of 68, INR of 1.1, and a normal CBC. She give no history of abnormal bruising or bleeding. Your next step is:

• A) Proceed with surgery• B) Consult hematology for further workup• C) Proceed with surgery after 4 units FFP• D) Proceed with surgery after 5 mg of Vitamin K SQ x1

– Answer: B. This patient has a high-risk surgery (head and neck) and therefore needs further workup (i.e. mixing study, etc.).



• Question Eight:– Question: What aspect of history, physical or laboratory

studies is associated with increased risk of post-operative wound infections?

• A) Baseline hemoglobin A1c• B) History of retinopathy• C) Preoperative glucose level• D) Use of insulin

– Answer: Preoperative blood glucose > 200 has been associated with increased risk of deep sternal wound infections in post-CABG patients (found to have OR of 10.2).



References

• Cardiovascular evaluation:– ACC/AHA Guideline on Perioperative Cardiovascular Evaluation for Noncardiac

Surgery, http://www.acc.org/clinical/guidelines/perio/update/pdf/perio_update.pdf

• Pulmonary evaluation:– Arozullah AM, Khuri SF, Henderson WG et al. Development and validation of a

multifactorial risk index for predicting postoperative pneumonia after major noncardiac surgery. Ann Intern Med 2001;135:847-857

– Beckles MA, Spiro SG, Colice GL et al. The physiologic evaluation of patients with lung cancer being considered for lung resectional surgery. Chest 2003;123:105S-114S

– Brooks-Brunn JA. Predictors of postoperative pulmonary complications following abdominal surgery. Chest 1997;111:564-71

– Brooks-Brunn JA. Postoperative atelectasis and pneumonia. Heart Lung 1995;24:94-115

– Datta D, Lahiri B. Preoperative evaluation of patients undergoing lung resection surgery. Chest 2003;123:2096-2103

– Garibaldi RA, Britt MR, Coleman ML et al. Risk factors for postoperative pneumonia. Am J Med 1981;70:677-80

– Wyser C, Stulz P, Soler M et al. Prospective evaluation of an algorithm for the functional assessment of lung resection candidates. Am J Respir Crit Care Med 1999;159:1450-6



References

• Anticoagulation:– The clinical impact of increased sensitivity PT and APTT coagulation assays.

Am J Clin Pathol 1999; 112:225. – Williams' Hematology. Beutler, E, Lichtman, MA, Coller, BS, et al (eds).

McGraw-Hill, New York, 6th edition, 2001; p. 1471 – Outcomes of patients with no laboratory assessment before anesthesia and a

surgical procedure. Mayo Clin Proc 1997; 72:505 – Usefulness of preoperative laboratory assessment of patients undergoing

elective herniorrhaphy. Arch Surg 1992; 127:801 – Management of anticoagulation before and after elective surgery. N Engl J

Med 1997; 336:1506• Diabetes:

– 1. Khan NA, Ghali WA. Perioperative management of diabetes mellitus. In: UpToDate, Rose, BD (Ed), UpToDate, Waltham, MA, 2005.

– 2. Trick WE, et al. Modifiable risk factors associated with deep sternal site infection after coronary artery bypass grafting. J Thorac Cardiovasc Surg 2000 Jan;119(1):108-14.

– 3. Latham R, et al. The association of diabetes and glucose control with surgical-site infections among cardiothoracic surgery patients. Infect Control Hosp Epidemiol 2001 Oct;22(10):607-12.

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