実験的肺空気塞栓に対する過換気の影響

Abstract

We attempted to elucidate effects of hyperventilation in experimental pulmonary air-embolism of dogs. Pulmonary air embolism was produced by air infusion 0.1 ml/kg/min. for 10 minuten (0.1 ml/kg) via inserted pulmonary artery catheter ; endotracheal anesthetized dogs with fentanyl and vecuronium bromide under mechanical ventilation. We measured hemodynamic variables and pH, blood gas (arterial, mixed venous blood) at baseline, post-air infusion and after recovered pulmonary artery pressure (PAP). In addition PAP recovery-times were counted. As results, PAP recovery-times in hyperventilation group (pH=7.50, PaCO₂=25 mmHg) were attenuated significantly compared with normoventilation (control) group (pH=7.40, PaCO₂=40 mmHg) ; these values were 14.2±5.2 min. versus 17.8±6.0 min. (n=8, p<0.05). On the threshould air volume of paradoxical air-embolism, we confirmed air bubbles in the left atrium and/or aorta with using transesophageal echocardiography and recognized 0.75±0.27 ml/kg (hyperventilation group), and 0.83±0.26 ml/kg (control) respectively ; there were no significant differences related to the ventilation-modus. We concluded that recovery-time of elevated pulmonary artery pressure was attenuated with induced hyperventilation in the experimental air embolism, but that hyperventilation revealed no beneficial effects on the threshold air volume of paradoxical air-embolism.