抄録
Pulmonary air embolism is a dreadful complication that may occur especially when patients undergo intracranial surgery in the sittting position. This study reports the effects of 100% oxygen ventilation, POB and SNP on the pulmonary circulation during venous air infusion. Fifty-seven mongrel dogs were anesthetized with pentobarbital sodium and pancuronium bromide, and ventilated with a mechanical respirator.
Measurements of the mean pulmonary arterial pressure (mPAP), pulmonary capillary wedge pressure (PCWP), mean systemic blood pressure (mBP), central venous pressure (CVP), cardiac output (CO), pulmonary shunting (QS/QT), pulmonary vascular resistance (PVR) and total peripheral resistance (TPR) were obtained. Twenty-six of these dogs were air infused at a rate of 0.15ml/kg/min and the other 31 at a rate of 0.09ml/kg/min. In the group of 26 dogs, eight were ventilated with 100% oxygen, nine were pretreated with POB, and nine with SNP. In the other group, ten dogs were pretreated with POB, ten with SNP, and the rest recieved no treatment. Air infusion caused an increase of PVR and QS/QT, the degree being dose dependent, but CO, mBP and TPR were unchanged. There was no significant effect on this rise of PAP in dogs ventilated with 100% oxygen, nor on the PAP, PVR and QS/QT in POB preterated dogs.
In the dogs air infused at a rate of 0.09ml/kg/min, SNP decreased PAP significantly in comparison to untreated controls, but did not influence the magnitude of the PAP increase, and there was also no effect on PVR and QS/QT compared with untreated controls. Based on the hemodynamic changes observed, it was suggested that the rise of PAP during air infusion is due to a partial transient obstruction in pulmonary arterioles and capillaries, and that this obstruction may therefore be a simple mechanical one.
