Physician Utilization of Therapeutic Hypothermia

Following Resuscitation from Cardiac Arrest

James W. Rhee, MD

April 29, 2004

The University of Chicago

Emergency Medicine Residency

Introduction

• Cardiac arrest– Greater than 90% mortality rate– No significant decline over past few decades

despite new drugs and improved access to electrical defibrillation

• Return of spontaneous circulation (ROSC)– Many patients go on to die during subsequent

hospitalization– Neurologic impairment often remains as a

lasting morbidity

Studies

Hypothermic Normothermic

Alive at 6 months with favorable neurologic status

53% (75/136) 35% (54/137)

ILCOR Advisory Statement

•Unconscious adult patients with ROSC after out-of-hospital VF cardiac arrest should be cooled to 32°C - 34°C for 12 - 24 hours

•Possible benefit for other rhythms or in-hospital cardiac arrest

Current Use

• Physician Utilization– Physician utilization of therapeutic

hypothermia following ROSC after cardiac arrest remains unclear

• Physician Experience– Initial experiences with hypothermia

• Guide future investigations• Development of critical pathways

Survey

• We conducted an internet-based survey of U.S. physicians in emergency medicine, pulmonary/critical care, and cardiology – Evaluate physician utilization of hypothermia

therapy– Assess physician opinions and experience

regarding induced hypothermia after cardiac arrest

Methods

• Institutional Review Board approval

• Health Insurance Portability and Accountability Act of 1996 – compliant

Methods

• 2000 electronic mail addresses randomly chosen– American College of Emergency Physicians– American Thoracic Society– American Heart Association

• Invitation to participate in survey sent to each address with a hyperlink leading to the survey itself

Methods

• Survey published via commercial survey provider (Infopoll.com, Dartmouth, Canada)

• Survey comprised of twelve questions– Demographic information

• Field of practice, geographic location, level of training, etc.

– Use of induced hypothermia• Methodology, reasons for non-use, etc.

– Free response at end of survey

Methods

• Results compiled by survey provider software

• Analysis and tabulation performed using a spreadsheet application (Excel, Microsoft Corp., Redmond, WA)

Results

2000 emails

1400 hits

265 responses (19%)

Demographics

Level of Training Practice location: staffingAttending 94% Residents and students present 79%Resident 3% No residents or students present 21%Fellow 3%

Practice location: hospital typeField of Practice Tertiary Academic Hospital 56%Emergency Medicine 41% Referral Hospital 22%Critical Care 13% Community Hospital 19%Cardiology 24% Other 3%Other 22%

Cardiac arrest patients treated per year:Practice location: hospital size up to 5 patients per year 24%More than 1000 beds 4% 6-10 patients per year 30%751-1000 beds 19% more than 10 patients per year 47%501-750 beds 17%251-500 beds 37%up to 250 beds 23%

Demographics

9%

27%

13% 20%

30%

Use of Therapeutic Hypothermia

Yes 13%

No 87%

Critical Care

(n=33)

Cardiology

(n=64)

Emergency

Medicine

(n=109)

All respondents

(n=263)

Yes No

5% 95%

11% 89%

29% 71%

13% 87%

Use of Therapeutic Hypothermia by Clinical Specialty

Not enough data

Haven’t considered it

Not in ACLS guidelines

Too technically difficult

Current methods cool too slow

Unsatisfactory initial attempts

0% 10% 20% 30% 40% 50%

Reason for nonuse- Percentage of respondents

49%

32%

32%

19%

9%

4%

Reasons Against Use of Hypothermia as a Therapeutic Tool

Cooling Technique

Cooling blankets

Ice / cold liquid packing

Ice / cold liquid gastric lavage

IV cooling catheter

Cooling mist

Other method

0% 10% 20% 30% 40% 50%

Cooling technique Percentage of respondents

50%

15%

13%

2%

2%

17%

Free Response

Have not heard of this treatment option 3

Resistance from hospital or other physicians 3

I am interested in technique, want to learn more 3

Plan on using it in the future -- now developing protocol 7

Literature not yet convincing 4

Lack of training -- too many resources required 5

Total number of free responses 80

Hypothermia Not Yet Incorporated

• Physicians have not yet incorporated the use of therapeutic hypothermia after cardiac arrest despite strong data and published guidelines recommending its use

• This conclusion appears to be consistent across the three specialties queried

Limitations

• Reflects practice at one point in time

• Selection bias – respondent population was skewed towards physicians practicing in larger hospitals and teaching institutions

• Western US not as well represented

Best Case

• As physicians at academic institutions and tertiary or referral hospitals were overrepresented – likely represents best case of current practice– Assume utilization of this new treatment

modality in the greater medical community will be less than in larger academically-oriented hospitals

Reasons for Lack of Incorporation

• Physicians not aware of strong literature supporting use of induced hypothermia

• Not part of standard guidelines– Advanced Cardiovascular Life Support

(ACLS)

• Technical constraints

Actions to Promote Use

• Physician education• Update ACLS• Share experiences

and protocol development

Future Technology

• Novel coolant fluids• Cold IV fluids• Cooling catheters

Research

• Method• Timing• Mechanism

Summary

• Physician use of hypothermia induction in patients resuscitated from cardiac arrest is low

• Reasons why physicians have not used hypothermia include lack of awareness of supporting data, technical constraints, and the lack of hypothermia protocol incorporation into ACLS

• Better understanding of the pathophysiology of resuscitation and the injury processes on which hypothermia acts will serve to further promote the use of this promising method to save lives

Acknowledgements

Ben Abella, MD

Annie Hueng

Lance Becker, MD

Terry Vanden Hoek, MD

Lynne Harnish

ERC