Effect of Cardiopulmonary Bypass on Pulmonary Function in Infants

Objective To evaluate the effect of the cardiopulmonary bypass (CPB) on the pulmonary function in infants with or withoutpulmonary hypertension in congential ventricular septal defect (VSD). MethodsTwenty infants with VSD were enrolled in the study fromJan. to Dec.2004. They were divided into two groups: pulmonary hypertension group and non-pulmonary hypertension group, ten infantsrespectively. Pulmonary function parameters were measured before CPB and 3, 6, 9, 12, 15, 18, 21, 24h after CPB, the following datawere recorded: duration for mechanical ventilation (Tmv) and staying in the cardiac intensive care unit (Tcicu) after cardiac surgery.Results Before CPB, the pulmonary function parameters in non-pulmonary hypertension group were more superior than in pulmonary hy-pertension group (P<0.01). By contraries, the pulmonary function parameters in every time stage after CPB statistically significant de-creased in non-pulmonary hypertension group (P<0.05), especially at 6, 9, and 15h after CPB (P<0.01). In pulmonary hyperten-sion group, the pulmonary function parameters in 3h after CPB were more improved than before CPB, though there was no statistical sig-nificance. But they had statistically significant decreased at9, 12, 15h after CPB (P<0.05). There was a similar change in pulmonaryfunction between two groups at 21, 24h after CPB. Conclusion Exposure to CPB adversely affects pulmonary function after surgicalrepair of VSD in infants. We consider that the benefits of the surgical correction in infants with pulmonary hypertension outweight the neg-ative effects of CPB on pulmonary function. We should improve cardiac function to avoid the presence of the nadir trough in pulmonaryfunction. The infants with pulomonary hypertension also have ability to wean from mechanical ventilation as soon as possible, if the hemo-dynamics is stable, and without the responsive pulmonary hypertension or pulmonary hypertension crisis after surgical repair.

Monitoring of Cerebral Oxygenation by Near-infrared Spectroscopy during Cardiopulmonary Bypass in Infants

Objective: To evaluate the use of near-infrared spectroscopy for monitoring cerebral oxygenation under different cardiopulmonary bypass models. Method: Twenty-four patients with ventricular septal defect and pulmonary hypertension undergoing open-heart surgery were assigned eight each to three groups, with respect to different cardiopulmonary bypass models: moderate hypothermia cardiopulmonary bypass, deep hypothermia low flow and deep hypothermia circulatory arrest. For each patient, cerebral oxygenation with near-infrared spectroscopy were monitored and the relative concentration changes in cerebral oxygenated hemoglobin, deoxygenated hemoglobin and oxidized cytochrome aa3 were calculated. Electroencephalography, biochemical indicators such as neuron-specific enolase and lactate, and performed correlation analyses for near-infrared spectroscopy data and biochemical indicators were also measured. Results: Near-infrared spectroscopy data and biochemical indicators for moderate hypothermia cardiopulmonary bypass and deep hypothermia low flow group showed no correlation. For deep hypothermia circulatory arrest group, oxygenated hemoglobin signal declined to a plateau （nadir） during the circulatory arrest period. The duration from reaching nadir until reperfusion “oxygenated hemoglobin signal nadir-time", and the minimum values of oxygenated hemoglobin, and oxidized cytochrome aa3 were closely correlated with increasing neuron-specific enolase and lactate. And, all patients whose oxygenated hemoglobin signal nadir-time was less than 35 min were free from behavioral evidence of brain injury. Conclusion: Near-infrared spectroscopy data including oxygenated hemoglobin signal nadir-time and the minimum of oxygenated hemoglobin and oxidized cytochrome aa3 showed strong correlation with other cerebral function assessment for deep hypothermia circulatory arrest. Oxygenated hemoglobin signal nadir-time determined by near-infrared spectroscopy can be useful in predicting the safe duration of circulatory arrest.