小儿单肺定容和定压通气对血流动力学呼吸力学及血气的影响

Changes of haemodynamics, pulmonary mechanics and blood gas in different ventilatory modes during one-lung ventilation

目的 探讨小儿单肺通气期间采用定容 (VCV)和定压 (PCV)两种不同通气模式对血流动力学、呼吸力学及血气的影响。方法 按美国麻醉协会病人全身情况评估 (ASA)I～II级择期行结扎术的先天性动脉导管未闭 (PDA)病儿 2 0例 ,麻醉诱导后气管插管 ,右侧卧位 ,先行双肺定容通气 (TLV VCV) ,再采用右肺单肺定容通气 (OLV VCV) ,2 5min后改为单肺定压通气 (OLV PCV) ,用旁气流通气监测法 (SSS)监测TLV VCV、OLV VCV、OLV PCV期间的呼吸力学参数 (Ppeak、Pplat、Raw、Cdyn、Mvi、Mve) ,同时经食管超声多普勒 (TED)监护仪连续监测血流动力学参数 (CO、SVR、SV、LVETi、ACC) ,并取动脉血作血气分析 (PaO2 、PaCO2 )。结果 单肺定容通气与双肺定容通气相比 ,Ppeak、Pplat、Raw显著增高 (P <0 0 1) ,Cdyn显著下降 (P <0 0 1) ;CO、SV显著下降 (P <0 0 5 ) ,SVR显著增加 (P <0 0 5 ) ;动脉血PaO2 显著下降 (P <0 0 1)。单肺定压通气与单肺定容通气相比 ,动脉血PaO2 显著上升 (P <0 0 5 )。结论 单肺通气可使气道压力阻力增加 ,肺顺应性下降 ,动脉血氧分压降低 ,外周血管阻力增加 ,心输出量下降 ;小儿单肺通气期间 ,采取定压通气模式 ,有利于改善肺泡氧合 ,预防和减轻单肺通气造成的低氧血症。

Objective: To investigate the changes of haemodynamics, pulmonary mechanics and blood gas in volume controlled and pressure controlled ventilatory patterns during one-lung ventilation (OLV). Methods: 20 patients with patent ductus arteriosus (PDA) underwent left thoracotomy PDA ligation with right OLV. The patients were divided into three groups: two-lung ventilation with volume controlled (TLV-VCV), one-lung ventilation with volume controlled (OLV-VCV), and one-lung ventilation with pressure controlled (OLV-PCV). After two-lung ventilation with VCV, one-lung ventilation was started by VCV and the ventilation mode was then switched to PCV. All measurements were made 25 min after initiation of the ventilation mode. The respiratory mechanics index was measured by side stream spirometry (SSS), including peak airway pressure (Ppeak), plateau pressure (Pplat), airway resistance (Raw), lung compliance (Cdyn) and inspiratory and expiratory minute ventilation (Mvi, Mve). Cardiac output (CO), stroke volume (SV), systemic vascular resistance (SVR), left ventricular ejectiontime (LVETi), and aortic blood flow acceleration (ACC) were also measured, by using the transesophageal Doppler (TED) monitor. Arterial blood gases was determined in every ventilation mode. Results: Ppeak、Pplat and Raw were significantly higher during OLV-VCV than that during TLV-VCV (P<0.01), whereas Cdyn was significantly lower (P<0.01). CO and SV decreased and SVR increased during OLV-VCV (P<0.05). Arterial oxygen pressure (PaO 2) significantly decreased during OLV-VCV (P<0.01). While PaO 2 was significantly increased during OLV-PCV (P<0.05). Conclusion: Haemodynamics, respiratory mechanics and arterial oxygen tension declines result in hypoxemia during one-lung ventilation. Pressure controlled ventilation appeared to be a better alternative.