Maybauer D M, Talke P O, Westphal M, Maybauer M O, Traber L D, Enkhbaatar P, Morita N, Traber D L
Department of Anaesthesiology, Investigational Intensive Care Unit, The University of Texas Medical Branch, and Shriners Burns Hospital for Children at Galveston, USA.
Anaesth Intensive Care. 2006 Jun;34(3):329-33. doi: 10.1177/0310057X0603400307.
Positive end-expiratory pressure (PEEP) is used to improve gas exchange, increase functional residual capacity, recruit air spaces, and decrease pulmonary shunt in patients suffering from respiratory failure. The effect of PEEP on extravascular lung water (EVLW), however, is still not fully understood. This study was designed as a prospective laboratory experiment to evaluate the effects of PEEP on EVLW and pulmonary lymph flow (QL) under physiologic conditions. Twelve adult sheep were operatively prepared to measure haemodynamics of the systemic and pulmonary circulation, and to assess EVLW In addition, the lung lymphatic duct was cannulated and a tracheostomy performed. The animals were then mechanically ventilated in the awake-state without end-expiratory pressure (PEEP 0). After a two-hour baseline period, PEEP was increased to 10 cmH2O for the duration of two hours, and then reduced back to 0 cmH2O. Cardiopulmonary variables, QL, and arterial blood gases were recorded intermittently; EVLW was determined two hours after each change in PEEP. The increase in PEEP resulted in a decrease in QL (7 +/- 1 vs 5 +/- 1 ml/h) and an increase in EVLW (498 +/- 40 vs 630 +/- 58 ml; P<0.05 each) without affecting cardiac output. As PEEP was decreased back to baseline, QL increased significantly (5 +/- 1 vs 10 +/- 2 ml/h), whereas EVLW returned back to baseline. This study suggests that institution of PEEP produces a reversible increase in EVLW that is linked to a decrease in QL.
呼气末正压（PEEP）用于改善呼吸衰竭患者的气体交换、增加功能残气量、复张肺泡及减少肺内分流。然而，PEEP对血管外肺水（EVLW）的影响仍未完全明确。本研究设计为一项前瞻性实验室实验，旨在评估生理条件下PEEP对EVLW及肺淋巴流量（QL）的影响。选取12只成年绵羊，通过手术准备来测量体循环和肺循环的血流动力学，并评估EVLW。此外，对肺淋巴管进行插管并实施气管切开术。随后在清醒状态下对动物进行机械通气，呼气末压力为0（PEEP 0）。经过两小时的基线期后，将PEEP增加至10 cmH₂O并持续两小时，然后再降至0 cmH₂O。间歇记录心肺变量、QL及动脉血气；每次PEEP改变两小时后测定EVLW。PEEP增加导致QL降低（7±1比5±1 ml/h）及EVLW增加（498±40比630±58 ml；均P<0.05），且不影响心输出量。当PEEP降至基线时，QL显著增加（5±1比10±2 ml/h），而EVLW恢复至基线。本研究提示，应用PEEP会使EVLW产生可逆性增加，且与QL降低相关。
