Cerebral hemodynamics during cardiopulmonary bypass in children using near-infrared spectroscopy.
We describe a new noninvasive method using near-infrared spectroscopy for monitoring cerebral hemodynamics during cardiopulmonary bypass in children. All patients were undergoing open heart operations for repair of congenital heart defects. Standardized anesthesia, an alpha-stat method of blood gas management, and nonpulsatile flow were used in all cases. All measurements during bypass were made after steady-state conditions had been reached. Cerebral blood flow was measured on 13 occasions in 4 children, aged between 4 and 10 months (median, 5 months). Values of 15.9 to 53.5 mL x 100 g-1 x min-1 were obtained. Cerebral blood volume was measured in 1 patient, aged 4 months. Volumes of 4.3 to 8.0 mL x 100 g-1 were obtained on bypass at full pump flow (2.4 L.min-1 x m-2). On bypass at half flow, the volume increased to 14.7 mL x 100 g-1. Change in cerebral blood volume with changing carbon dioxide tension (CBVR) was measured in 13 patients aged from 1 to 90 months (median, 13.5 months). Preoperatively, CBVR was 0.12 +/- 0.07 mL x 100 g-1 x kPa-1 and was independent of mean arterial pressure, which remained between 40 and 80 mm Hg in all cases. During hypothermic bypass (25 degrees C), CBVR was significantly reduced to 0.05 +/- 0.02 mL x 100 g-1 x kPa-1. In addition, there were three values at mean arterial pressure of lower than 40 mm Hg in which CBVR was negative (-0.04 +/- 0.01 mL x 100 g-1 x kPa-1). We conclude that near-infrared spectroscopy is useful for the noninvasive investigation of cerebral hemodynamics during cardiopulmonary bypass.
Fallon
P
P
Department of Neurosciences, Institute of Child Health/Hospital for Sick Children, London, England.
Roberts
I
I
Kirkham
F J
FJ
Elliott
M J
MJ
Lloyd-Thomas
A
A
Maynard
R
R
Edwards
A D
AD
D002245:Carbon Dioxide / Q000097:blood; D002315:Cardiopulmonary Bypass; D002560:Cerebrovascular Circulation / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D006330:Heart Defects, Congenital / Q000601:surgery*; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D007223:Infant; D008991:Monitoring, Physiologic / Q000379:methods; D017550:Spectroscopy, Fourier Transform Infrared
D002245:Carbon Dioxide