Theres H, Binkau J, Laule M, Heinze R, Hundertmark J, Blobner M, Erhardt W, Baumann G, Stangl K
Charité, Med. Klinik I, Berlin, Germany.
Crit Care Med. 1999 May;27(5):953-8. doi: 10.1097/00003246-199905000-00033.
To examine determinants of right ventricular function throughout the ventilatory cycle under volume-controlled mechanical ventilation with various positive end-expiratory pressure (PEEP) stages.
Prospective observational animal pilot study.
Animal research laboratory at a university hospital.
Eight healthy swine under volume- controlled mechanical ventilation.
Flow probes were implanted in eight swine in order to continuously measure blood flow in the pulmonary artery and inferior vena cava. After a recovery phase of 14 days, the swine were subjected to various PEEP stages (0, 5, 10 cm H2O) during volume-controlled positive pressure ventilation.
Continuous flow measurement took place in the pulmonary artery and inferior vena cava. Data on standard hemodynamic parameters were additionally acquired. Respiration-phase-specific analysis of right ventricular cardiac output and of additional hemodynamic function parameters followed, after calculation of mean values throughout five respiration cycles. PEEP at 5 cm H2O led to significant decreases in inferior vena cava flow (4.1%), and in right ventricular cardiac output (5.2%); the respective decreases at PEEP 10 cm H2O were 13.9% and 18.3%. In the inspiration phase at PEEP 10 cm H2O, results revealed an overproportionally pronounced decrease in comparison with the expiration phase in inferior vena cava flow (-24.6% vs. -10%) and right ventricular cardiac output (-35% vs. -13.5%). This phenomenon is presumably caused by a PEEP-related increase in mean airway pressure by the amount of 10.7 cm H2O in inspiration.
Increases in PEEP during volume-controlled mechanical ventilation leads to respiration-phase-specific reduction of right ventricular cardiac output, with a significantly pronounced decrease during the inspiration phase. This decrease in cardiac output should be taken into particular consideration for patients with already critically reduced cardiac output.
研究在不同呼气末正压（PEEP）阶段的容量控制机械通气过程中，右心室功能在整个通气周期的决定因素。
前瞻性观察性动物初步研究。
大学医院的动物研究实验室。
八只接受容量控制机械通气的健康猪。
在八只猪体内植入流量探头，以持续测量肺动脉和下腔静脉的血流。经过14天的恢复期后，在容量控制正压通气期间，使猪经历不同的PEEP阶段（0、5、10 cmH₂O）。
对肺动脉和下腔静脉进行连续血流测量。另外获取标准血流动力学参数的数据。在计算五个呼吸周期的平均值之后，对右心室心输出量和其他血流动力学功能参数进行呼吸相特异性分析。5 cmH₂O的PEEP导致下腔静脉血流显著减少（4.1%），右心室心输出量显著减少（5.2%）；10 cmH₂O的PEEP时相应的减少分别为13.9%和18.3%。在10 cmH₂O的PEEP时的吸气相，结果显示与呼气相相比，下腔静脉血流（-24.6%对-10%）和右心室心输出量（-35%对-13.5%）的减少比例过大且明显。这种现象可能是由于吸气时平均气道压因PEEP相关因素升高了10.7 cmH₂O所致。
容量控制机械通气期间PEEP的增加导致右心室心输出量出现呼吸相特异性降低，在吸气相时降低尤为明显。对于心输出量已严重降低的患者，应特别考虑这种心输出量的减少。
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