Surface cooling for induction of mild hypothermia in conscious healthy volunteers - a feasibility trial.
BACKGROUND
Animal and human studies suggest beneficial outcome effects of mild hypothermia for stroke, for acute myocardial infarction, and for cardiogenic shock. The aim of this study was to investigate the feasibility and safety of non-invasive surface cooling for induction and maintenance of mild hypothermia (32 to 34°C) in healthy, conscious volunteers.


METHODS
The trial was set at a clinical research ward in a tertiary care center, and included 16 healthy male volunteers 18 to 70 years old. Surface cooling was established by a novel non-invasive cooling pad with an esophageal target temperature of 32 to 34°C and maintenance for six hours. Shivering-control was achieved with meperidine and buspirone and additional administration of magnesium in eight subjects.


RESULTS
The primary endpoint to reach a target temperature of 32 to 34°C was only reached in 6 of the 16 participating subjects. Temperatures below 35°C were reached after a median cooling time of 53 minutes (38 to 102 minutes). Cooling rate was 1.1°C/h (0.7 to 1.8°C). Additional administration of magnesium had no influence on cooling rate. At no time during the cooling procedure did the participants report uncomfortable conditions for which termination of cooling had to be considered. No severe skin damage was reported.


CONCLUSIONS
Cooling to body temperature below 35°C by the use of non-invasive surface cooling is feasible and safe in conscious healthy volunteers. Further studies are needed to investigate an altered cooling protocol to achieve temperatures below 35°C.


BACKGROUND
ISRCTN: ISRCTN50530495.
Department of Emergency Medicine, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria.
Christoph
C
Testori
Fritz
F
Sterz
Wilhelm
W
Behringer
Alexander
A
Spiel
Christa
C
Firbas
Bernd
B
Jilma
D000328:Adult; D001830:Body Surface Area; D001831:Body Temperature / Q000502:physiology; D003243:Consciousness; D005240:Feasibility Studies; D064368:Healthy Volunteers; D006801:Humans; D007036:Hypothermia, Induced / Q000009:adverse effects / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D055815:Young Adult