鼻罩压力支持通气对肺部气体交换的影响

Improvement of gas exchange by nasal pressure Support ventilation in upper abdominal surgical patients under epidural block

本组40例硬膜外阻滞下行上腹部手术的患者,用 BiPAP 呼吸器行鼻罩法吸气压力支持通气(PSV),在吸氧浓度不变的情况下,均明显地提高了患者术中的动脉血 O_2分压(PaO_2),平均升高1.6 kPa;O_2饱和度(SaO_2),平均升高3%,而 PaCO_2改变不明显,与 PaO_2升高不成比例。8例从 PSV 改为间歇正压通气(IPPV)后,6例 SaO_2明显降低2%～10%,提示鼻罩 PSV 改善上腹部手术中气体交换并非过度通气所致,而是改善了肺通气与血流比例和促进膈肌功能的结果。

Nearly all upper abdominal operations under epidural block are associated with reduction in SaO_2 and PaO_2.The effects of restoring SaO_2 by using a nasal pressure support ventilation (PSV) were investigated in 40 upper abdominal surgical patients.All patients received epidural block with pethidine 50 mg and promethazine 50 mg as the supplementary drugs.Reduction in SpO_2 following intro- abdominal procedures was observed in 36 of 40 patients.All patients then were ventilated with a pressure support ventilation by nasal mask.Inspiratory pressure was set at 10.1±1.1 cmH_2O, SpO_2 incrcased by 2% to 10% in 37 of 40 patients but PaCO_2changed little.In 8 randomly patients, the efficacy of nasal PSV was compared with a IPPV with same F_1O_2 and P_(ET)CO_2.After muscular paralysis,IPPV was used instead of PSV for 15 min.Desaturation from 2 % to 10% occurred in 6 of 8 patients.The results suggested that nasal PSV reduced the work of breathing and optimized the diaphragmatic function,and then improved gas exchange.