呼气末正压通气对伴有低血容量趋势行机械通气患者血流动力学的影响

目的探讨呼气末正压（PEEP）对低血容量趋势患者行机械通气时血流动力学的影响。 方法选择20例伴有低血容量趋势需行机械通气的患者作为研究对象。所有患者均在基础呼吸模式上分别加用PEEP 0、5、10、15 cmH₂O，每次持续约30 min。记录所有患者的心率、平均动脉压（MAP）、肺动脉嵌压（PAWP）、每搏指数（SVI）、心排血量（CO）、心指数及体循环血管阻力指数（SVRI）等血流动力学指标，中心静脉压（CVP）、髂总静脉压（CIVP）及ΔCVP等静脉回流梯度指标，吸气峰压（PIP）、气道阻力（RAW）、用吸气暂停键测出平台压（Pplat）、气道平均压力（Pmean）及肺循环血管阻力指数（PVRI）等呼吸力学指标。 结果随着PEEP水平的增加，患者心率、PAWP及SVRI均显著增加，而MAP、CO、心指数及SVI则逐渐下降（F = 20.311、15.100、32.915、15.100、198.635、435.100、17.000，P均< 0.001），且CO于PEEP为5 cmH₂O时与PEEP为0 cmH₂O时比较，已经出现显著降低[（5.31 ± 0.11）L / min vs.（5.46 ± 0.24）L / min]；患者的CVP、CIVP的水平逐渐升高，而ΔCVP逐渐下降（F = 47.879、27.578、21.393，P均< 0.001）；患者的PIP、Pplat、Pmean、PVRI水平均逐渐升高，且PEEP为15 cmH₂O时达最高（F = 67.152、74.025、818.208、31.141，P均< 0.001），而RAW在不同PEEP间比较差异无统计学意义（F = 2.082，P = 0.131）。 结论对有低容量趋势行机械通气的患者，当PEEP ≥ 5 cmH₂O即出现CO明显下降，因此对于有低容量趋势患者尽量使用最小PEEP来达到治疗目的。

Effect of positive end expiratory pressure on hemodynamics in patients with hypovolemic tendency undergoing mechanical ventilation

ObjectiveTo investigate the effect of positive end expiratory pressure (PEEP) on hemodynamics in patients with hypovolemic tendency undergoing mechanical ventilation. MethodsTotally 20 patients with hypovolemic tendency undergoing mechanical ventilation were enrolled in this study. All patients were given PEEP of 0, 5, 10, and 15 cmH₂O in the basal breathing mode for about 30 min each time. The hemodynamic indexes of heart rate, mean arterial pressure (MAP), pulmonary arterial wedge pressure (PAWP), stroke volume index (SVI), cardiac output (CO), cardiac index and systemic vascular resistance index (SVRI), venous reflux gradient indexes of central venous pressure (CVP), common iliac venous pressure (CIVP) and ΔCVP, and respiratory mechanics indexes of peak inspiratory pressure(PIP), airway resistance (RAW), platform pressure (Pplat), mean airway pressure (Pmean) and pulmonary vascular resistance index (PVRI) were detected and compared among different PEEP levels. ResultsAs the level of PEEP went up, the heart rate, PAWP and SVRI increased significantly, the MAP, CO, cardiac index and SVI decreased gradually (F = 20.311, 15.100, 32.915, 15.100, 198.635, 435.100, 17.000; all P < 0.001), and the CO level in the PEEP of 5 cmH₂O was much lower than that in the PEEP of 0 cmH₂O [(5.31 ± 0.11) L / min vs. (5.46 ± 0.24) L / min]. The levels of CVP and CIVP increased gradually, and ΔCVP decreased (F = 47.879, 27.578, 21.393; all P < 0.001). Meanwhile, the levels of PIP, Pplat, Pmean and PVRI increased gradually, and peaked at the PEEP of 15 cmH₂O (F = 67.152, 74.025, 818.208, 31.141; all P < 0.001). However, there was no significant difference in RAW among different PEEP levels (F = 2.082, P = 0.131). ConclusionWhen PEEP is no less than 5 cmH₂O, CO significantly decreases in patients with hypovolemic tendency undergoing mechanical ventilation, so the minimal PEEP should be used for therapeutic purposes.