Introduction: Hypothermia may improve outcome after global cerebral ischemia We previously reported on selective brain cooling (SBC) in piglets after cardiac arrest (1). Surface cooling the head may cause regional blood flow gradients compared to total body cooling (TBC). In this study, we compared the effects of SBC and TBC on cerebral blood flow (CBF) and metabolism (CMRO2) during and after resuscitation from cardiac arrest. Methods: Piglets (4-8 kg) were anesthetized (pantobarbital), mechanically ventilated and vascular catheters were inserted. Six regional brain temperatures (T) and their mean were monitored continuously. Animals underwent 8 minutes of ventricular fibrillation, 6 minutes of CPR, defibrillation, and received either TBC (n=5) or SBC (n=4) beginning during CPR and continuing for 2 hours of reperfusion (R). Target brain T was 32-33 °C. Control animals were kept normothermic (NT, n=5). Total and regional CBF (microspheres) was measured at baseline, during CPR and at 15, 45 and 120 minutes R. CMRO2 was calculated as CBF × (CaO2 - CvO2). Between group variables were analyzed with one-way ANOVA and Bonferroni's correction. Significance was set at p<0.05. Results: Data are mean ± s.d. Groups did not differ at baseline or during CPR. At 15R, brain T was equally lowered in TBC and SBC animals (33.7 ± 0.02°C, 34.7±0.6°C, respectively) compared to NT animals (37.4 ± 0.4°C). CBF and CMRO2 did not differ. Time Group Avg. brain T(°C) CBF (mL/100g/min) CMRO2 (mL/100g/min) NT 38.0±0.6 41±10 2.44±0.92 45R TBC 29.8±2.1* 36±22 1.91±1.92 SBC 32.8±1.1* 37±15 1.07±0.60 NT 38.2±0.5 38±1 2.11±0.31 120R TBC 30.9±3.6* 24±10* 1.24±0.73 SBC 33.4±1.7 31±9 1.41±0.53 (*p < 0.05 vs. NT) Blood flow to supratentorial and infratentorial brain regions did not differ between TBC and SBC animals at any time. Conclusions: After cardiac arrest, CBF and CMRO2 are equally affected by TBC and SBC. Both TBC and SBC effectively reduce CMRO2 during resuscitation. Surface cooling the head does not affect regional distribution of CBF.
|Original language||English (US)|
|Journal||Critical care medicine|
|Issue number||1 SUPPL.|
|State||Published - Dec 1 1999|
ASJC Scopus subject areas
- Critical Care and Intensive Care Medicine