Pilot study of rapid infusion of 2 L of 4 degrees C normal saline for induction of mild hypothermia in hospitalized, comatose survivors of out-of-hospital cardiac arrest.
BACKGROUND
Recent clinical studies have demonstrated that mild hypothermia (32 degrees C to 34 degrees C) induced by surface cooling improves neurological outcome after resuscitation from out-of-hospital cardiac arrest. Results from animal models suggest that the effectiveness of mild hypothermia could be improved if initiated as soon as possible after return of spontaneous circulation. Infusion of cold, intravenous fluid has been proposed as a safe, effective, and inexpensive technique to induce mild hypothermia after cardiac arrest.


RESULTS
In 17 hospitalized survivors of out-of-hospital cardiac arrest, we determined the effect on temperature and hemodynamics of infusing 2 L of 4 degrees C cold, normal saline during 20 to 30 minutes into a peripheral vein with a high-pressure bag. Data on vital signs, electrolytes, arterial blood gases, and coagulation were collected before and after fluid infusion. Cardiac function was assessed by transthoracic echocardiography before fluid administration and 1 hour after infusion. Passive (fans, leaving patient uncovered) or active (cooling blankets, neuromuscular blockade) cooling measures were used to maintain mild hypothermia for 24 hours. Infusion of 2 L of 4 degrees C cold, normal saline resulted in a mean temperature drop of 1.4 degrees C 30 minutes after the initiation of infusion. Rapid infusion of fluid was not associated with clinically important changes in vital signs, electrolytes, arterial blood gases, or coagulation parameters. The initial mean ejection fraction was 34%, and fluid infusion did not affect ejection fraction or increase central venous pressure, pulmonary pressures, or left atrial filling pressures as assessed by echocardiography. Passive measures were ineffective in maintaining hypothermia compared with active measures.


CONCLUSIONS
Infusion of 2 L of 4 degrees C cold, normal saline is safe and effective in rapidly lowering body temperature in survivors of out-of-hospital cardiac arrest.
Kim
Francis
F
Department of Medicine, Harborview Medical Center, University of Washington, Seattle, WA, USA. fkim@u.washington.edu
Olsufka
Michele
M
Carlbom
David
D
Deem
Steven
S
Longstreth
W T
WT
Hanrahan
Margret
M
Maynard
Charles
C
Copass
Michael K
MK
Cobb
Leonard A
LA
D000328:Adult; D003080:Cold Temperature; D003128:Coma / Q000209:etiology / Q000628:therapy*; D006323:Heart Arrest / Q000628:therapy*; D006801:Humans; D006993:Hypnotics and Sedatives / Q000627:therapeutic use; D007036:Hypothermia, Induced / Q000379:methods; D007262:Infusions, Intravenous; D007297:Inpatients; D008874:Midazolam / Q000627:therapeutic use; D008875:Middle Aged; D010865:Pilot Projects; D012965:Sodium Chloride / Q000008:administration & dosage / Q000627:therapeutic use*; D017741:Survivors
D006993:Hypnotics and Sedatives; D012965:Sodium Chloride; D008874:Midazolam