Cerebral Oxygenation during Pediatric Cardiac Surgery: Identification of Vulnerable Periods using Near-infrared Spectroscopy

Objective: Neurologic sequelae remain a well-recognized complication of pediatric cardiac surgery. The aetiology of neurologic injury is almost certainly multifactorial, imbalance between cerebral oxygen supply and demand is likely to play an important role. We sought to measure regional cerebral oxygenation in children undergoing cardiac surgery using nearinfrared spectroscopy to ascertain such vulnerable periods. Materials and methods: This study is an observational study of 18 children (median age 1.3 years) undergoing cardiac surgery. Regional cerebral oxygenation was monitored using the INVOS3100 cerebral oximeter and related to hemodynamic parameters at each stage of the procedure. Results: Prior to the onset of bypass, 10 patients had a decrease in regional cerebral oxygenation, reaching a saturation less than 35% in 5 cases. The most common cause was handling and dissection around the heart prior to and during caval cannulation. With institution of bypass, regional cerebral oxygenation increased. Discontinuation of bypass caused a precipitous decrease in regional cerebral oxygenation in three patients, reaching less than 40%. Conclusions: These observations suggest that the preand early post-bypass periods are vulnerable times for provision of adequate cerebral oxygenation. Near-infrared spectroscopy is a promising tool for monitoring O2 supply/demand relationships especially during circulatory arrest.