Assessment of cerebrovascular autoregulation during halothane and propofol anesthesia by tilting and transcranial doppler sonography in infants 915

Introduction: In order to assess cerebrovascular autoregulation(CA) non-invasively we studied reaction of CBFV to orthostasis provoked by tilting during halothane (h) and propofol (p) anesthesia; as (h) compromises and (p) preserves cerebrovascular autoregulation. Methods: 20 healthy infants < ly were studied randomly during minor elective surgery. CBFV were assessed in MCA with a transcranial Doppler system (DWL, Multi Dop X; ISPTA: 1,5-5 mW/cm2) allowing continuous measurements. Data were analysed by Wilcoxon-signed-rank-test. Tilting-test: Infants were quickly tilted by 40° from supine to orthostatic head-up position, kept tilted for 2 min and then tilted back. Results: During halothane anesthesia diastolic CBFV(Vdiast) were significantly lower after 20 sec (63% ±24; p<0.005) and 2 min of tilting (64% ±20; p<0.005) as compared to respective values obtained during premedication (20 sec: 92% ±22; 2 min: 90% ±18); during propofol anesthesia Vdiast (92% ±9 and 95% ±11) were not significantly different from values obtained during premedication (20 sec: 89%±23; 2 min: 81% ±13). Significant alterations were also observed in mean velocities, systolic velocities did not show any significant difference. Conclusion: Vdiast shows the most significant reaction in states of compromised cerebrovascular autoregulation, suggesting the reaction of Vdiast as the most sensitive sign of intact CA. Supported by the Austrian Research Foundation (FWF-Nr-9342) & DWL Instruments, Germany