CEREBRAL OXYGENATION DURING PEDIATRIC CARDIAC-SURGERY - IDENTIFICATION OF VULNERABLE PERIODS USING NEAR-INFRARED SPECTROSCOPY

Objective: Neurologic sequelae remain a well recognised complication o f paediatric cardiac surgery, Monitoring of cerebral oxygenation may b e a useful technique for identifying vulnerable periods for the develo pment of neurologic injury. We sought to measure regional cerebral oxy genation in children undergoing cardiac surgery using near infrared sp ectroscopy to ascertain such vulnerable periods. methods: Observationa l study of 18 children (median age 1.3 years) undergoing cardiac surge ry (17 with cardiopulmonary bypass, 8 with circulatory arrest). Region al cerebral oxygenation was monitored using the INVOS 3100 cerebral ox imeter and related to haemodynamic parameters at each stage of the pro cedure. Results: Prior to the onset of bypass. 10 patients had a decre ase in regional cerebral oxygenation of greater than or equal to 15% p oints, reaching an absolute haemoglobin saturation less than 35% in 5 cases. The most common cause was handling and dissection around the he art prior to and during caval cannulation, With institution of bypass, regional cerebral oxygenation increased by a mean 18% points to a mea n maximum of 75%. During circulatory arrest regional cerebral oxygenat ion decreased with rate of decay influenced by temperature at onset of arrest (0.25%min at < 20 degrees C: 2%min at > 20 degrees C). Reperfu sian caused an immediate increase in regional cerebral oxygenation fol lowed by a decrease during rewarming. Discontinuation of bypass caused a precipitous decrease in regional cerebral oxygenation in 5 patients , reaching less than 50% in 3 patients, Conclusions: These observation s suggest that the prc-and early post-bypass periods are vulnerable li mes for provision of adequate cerebral oxygenation, Near infrared ed s pectroscopy is a promising tool for monitoring O-2 supply/demand relat ionships especially during circulatory arrest, (C) 1998 Elsevier Scien ce B.V, All rights reserved.