Non-invasive assessment of cerebral oxygen metabolism following surgery of congenital heart disease.

Abstract

Cerebral protection is a major issue in the treatment of infants with complex congenital heart disease. We tested a new device combining tissue spectrometry and laser Doppler flowmetry for non-invasive determination of cerebral oxygen metabolism following cardiac surgery in infants. We prospectively measured regional cerebral oxygen saturation cSO 2 and microperfusion (rcFlow) in 43 infants 12-24 h following corrective ( n = 30) or palliative surgery ( n = 13) of congenital heart defects. For comparison, cerebral blood flow (CBF) was determined by colour duplex sonography of the extracranial cerebral arteries. Cerebral fractional tissue oxygen extraction, approximated cerebral metabolic rate of oxygen (aCMRO 2 ) and cerebral metabolic rate of oxygen (CMRO 2 ) were calculated. cSO 2 was lower [54.6% (35.7-64.0) vs 59.7% (44.5-81.7); P < 0.01] after neonatal palliation, while rcFlow [69.7 AU (42.5-165.3) vs 77.0 AU (41.2-168.1); P = 0.06] and cerebral fractional tissue oxygen extraction [0.34 (0.24-0.82) vs 0.38 (0.17-0.55); P = 0.63] showed a trend towards lower values. We found a positive correlation between aCMRO 2 and CMRO 2 ( r = 0.27; P = 0.03). aCMRO 2 was significantly lower after neonatal palliation [4.0 AU (2.1-6.3) vs 4.9 AU (2.2-15.6); P = 0.02]. According to our experience, combined photospectrometry and laser Doppler flowmetry enable non-invasive assessment of cerebral oxygen metabolism. The method promises new insights into perioperative cerebral perfusion following palliation or corrective surgery in infancy.