Physiologic characteristics of cold perfluorocarbon-induced hypothermia during partial liquid ventilation in normal rabbits.
Because perfluorocarbon (PFC) liquid contacts closely with the alveolar capillaries during partial liquid ventilation (PLV), PLV with cold PFC may be used for the induction of hypothermia. Twenty rabbits were randomized to PFC-induced hypothermia (PH) (n = 7; core temperature 35 degrees +/- 1 degrees C), surface hypothermia (SH) (n = 7; 35 degrees +/- 1 degrees C), or normothermia (n = 6; 39 degrees +/- 1 degrees C). We induced PH by repeated in situ exchanges of 0 degrees C perfluorodecalin during PLV. At the establishment (0 min) of hypothermia in the PH group, oxygen consumption (P = 0.04) and oxygen extraction ratio (P = 0.01) decreased from normothermic condition. Metabolic (oxygen consumption, oxygen extraction ratio, serum lactate level) and hemodynamic variables (heart rate, blood pressure, cardiac output, pulmonary artery pressure) of the PH group were not different from those of the SH group at 0, 30, 60, 90, and 120 min of hypothermia. The difference in temperature between the pulmonary artery and rectum during the hypothermic period was smaller in the PH group compared with the SH group (P = 0.033). In conclusion, hypothermia may be induced during PLV by using cold PFC. This "pulmonary method" of cooling was comparable to a systemic method of cooling with regard to a few important physiologic variables, while maintaining a narrower interorgan temperature difference.


CONCLUSIONS
The induction of moderate hypothermia was feasible in rabbits by administrating cold perfluorocarbon liquid into the lung. Physiologic changes induced by this pulmonary cooling were comparable to those induced by systemic cooling. Our method may be regarded as a methodological advance in the field of therapeutic hypothermia.
Hong
Sang-Bum
SB
Division of Pulmonary and Critical Care Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Koh
Younsuck
Y
Shim
Tae-Sun
TS
Lee
Sang D
SD
Kim
Woo S
WS
Kim
Dong S
DS
Kim
Won D
WD
Lim
Chae-Man
CM
D000818:Animals; D001831:Body Temperature; D005466:Fluorocarbons / Q000008:administration & dosage*; D006439:Hemodynamics; D006863:Hydrogen-Ion Concentration; D007036:Hypothermia, Induced / Q000379:methods; D019344:Lactic Acid / Q000097:blood; D021061:Liquid Ventilation; D010101:Oxygen Consumption; D011817:Rabbits
D005466:Fluorocarbons; D019344:Lactic Acid