Ranieri V M, Giuliani R, Cinnella G, Pesce C, Brienza N, Ippolito E L, Pomo V, Fiore T, Gottfried S B, Brienza A
Istituto di Anestesiologia e Rianimazione, Policlinico, Università di Bari, Italy.
Am Rev Respir Dis. 1993 Jan;147(1):5-13. doi: 10.1164/ajrccm/147.1.5.
Dynamic hyperinflation and intrinsic positive end-expiratory pressure (PEEPi) are observed in patients with chronic obstructive pulmonary disease (COPD) and flow limitation. Several reports suggest that PEEP levels approaching PEEPi reduce inspiratory load due to PEEPi, without further hyperinflation. Hence PEEP should not increase intrathoracic pressure or affect hemodynamics and gas exchange. To verify this hypothesis, the effects of PEEP (0 to 15 cm H2O) on respiratory mechanics, hemodynamics, and gas exchange were studied in nine COPD patients during controlled mechanical ventilation. PEEP levels approaching PEEPi (9.8 +/- 0.5 cm H2O) did not affect the expiratory flow/volume relationship, confirming the presence of flow limitation. PEEP levels of 5 and 10 cm H2O did not change lung volume and PEEPi in the respiratory system (PEEPtot,rs) and chest wall (PEEPtot,cw) or affect hemodynamics and gas exchange. When applied PEEP overcame PEEPi, changes in lung volume and the expiratory flow/volume relationship were observed. PEEPtot,rs and PEEPtot,cw also increased. Under these circumstances, PEEP increased static elastance in both the respiratory system and the chest wall, reducing cardiac index and affecting hemodynamics and gas exchange. Our data show that in mechanically ventilated COPD patients with PEEPi due to flow limitation, PEEP levels exceeding the 85% of PEEPi (Pcrit) caused further hyperinflation and compromised hemodynamics and gas exchange.
在患有慢性阻塞性肺疾病（COPD）且存在气流受限的患者中可观察到动态肺过度充气和内源性呼气末正压（PEEPi）。一些报告表明，接近PEEPi的PEEP水平可降低由PEEPi引起的吸气负荷，而不会导致进一步的肺过度充气。因此，PEEP不应增加胸内压或影响血流动力学及气体交换。为验证这一假设，我们对9例接受控制性机械通气的COPD患者研究了PEEP（0至15 cm H₂O）对呼吸力学、血流动力学及气体交换的影响。接近PEEPi（9.8±0.5 cm H₂O）的PEEP水平并未影响呼气流量/容积关系，证实存在气流受限。5 cm H₂O和10 cm H₂O的PEEP水平并未改变呼吸系统（PEEPtot,rs）和胸壁（PEEPtot,cw）的肺容积及PEEPi，也未影响血流动力学及气体交换。当应用的PEEP超过PEEPi时，可观察到肺容积及呼气流量/容积关系的变化。PEEPtot,rs和PEEPtot,cw也增加。在这种情况下，PEEP增加了呼吸系统和胸壁的静态弹性，降低了心脏指数并影响了血流动力学及气体交换。我们的数据表明，在因气流受限而存在PEEPi的机械通气COPD患者中，超过PEEPi的85%（Pcrit）的PEEP水平会导致进一步的肺过度充气，并损害血流动力学及气体交换。
