EFFECTS OF POSITIVE AND NEGATIVE-PRESSURE VENTILATION ON CEREBRAL BLOOD-VOLUME OF NEWBORN-INFANTS

The effects of intermittent positive airway and continuous negative ex trathoracic pressure ventilation on cerebral blood volume in preterm i nfants were studied using near infrared spectroscopy. In 12 infants co ntinuous negative extrathoracic pressure caused a median decrease in c erebral blood volume of 0.14 ml/100 ml brain (95% confidence intervals (CI) 0.035-0.280) compared with no respiratory support. Oxygenated an d deoxygenated haemoglobin also decreased, implying increased venous d rainage as the main effect. In 17 infants intermittent positive pressu re ventilation also caused a median reduction in cerebral blood volume of 0.06 ml/100 ml brain (95% CI 0.010-0.115) compared with endotrache al positive airway pressure. Deoxygenated haemoglobin increased by 0.0 7 ml/100 ml brain (95% CI 0.010-0.100) while oxygenated haemoglobin de creased by 0.10 ml/100 mi brain (95% CI 0.005-0.175). The increase in deoxygenated haemoglobin implies decreased venous drainage and the dec rease in oxygenated haemoglobin implies that other factors may also be significant. Heart rate, blood pressure and oxygen saturation were mo nitored continuously and remained stable.