PEEP对心脏前负荷的影响

PEEP对心脏前负荷的影响,北京协和医院杜斌,病例摘要,WYG, M/51, 1629632DOA: 2009/06/18PMHx: HTN, DMCC: 发热, 皮疹2月, 憋气1月Dx:肺间质病变原因待查急性呼吸功能衰竭休克,病例摘要,入ICU时循环功能HR88 bpmNBP84/58 mmHgCVP16 mmHg呼吸机设置FiO21.0PS15 cmH2OPEEP20 cmH2O,CVP = 16 mmHg能否除外低血容量是否需要输液提高前负荷,CVP与前负荷,RVEDV / RVEDP / RAP / CVP,Cardiac Output,容量负荷反应组与无反应组的CVP,PEEP对CVP的影响,Saner FH, Pavlakovic G, Gu Y, et al. Effects of positive end-expiratory pressure on systemic haemodynamics, with special interest to central venous and common iliac venous pressure in liver transplanted patients. Eur J Anaesth 2006; 23: 766-771,间断正压通气对心输出量的影响,Cournand A, Motley HL, Werko L, et al. Physiological studies of the effects of intermittent positive pressure breathing on cardiac output in man. Am J Physiol 1948; 152: 162-174.,心输出量下降,右心室充盈受限,静脉回流,胸腔内压(ITP) ,正压通气,PEEP诱导的CO改变,CO = HR x SV,SV的影响因素,Viquerat CE, Righetti A, Suter PM: Biventricular volumes and function in patients with adult respiratory distress syndrome ventilated with PEEP. Chest 1983; 83: 509-514.,跨壁压的概念,5 cmH2O,20 cmH2O,跨壁压的概念,5 cmH2O,20 cmH2O,15 cmH2O,心脏的跨壁压,Thorax,Venous Return,LV Ejection,Increasing ITPDecreases the pressure gradients for venous return and LV ejection,Decreasing ITPIncreases the pressure gradients for venous return and LV ejection,PEEP对跨壁压的影响,PEEP对跨壁压的影响,胸腔内压(ITP) 概念, ,Esophageal,Pleural,Cardiacfossa,Cardiacsurface,Intrathoracic Pressure,Scharf S: Ventilatory support in cardiac failure. In The Ill Cardiac Patient. Edited by Kvetan V, Dantzker DR. Philadelphia: Lippincott-Raven; 1996: 29-45.,正压通气对肺容积的影响,气道阻力呼吸系统顺应性,PEEP对CVP的影响 测定方法,短暂脱离呼吸机CVP首先降低到谷值，然后因心室负荷改变而逐渐升高约在去除PEEP 2-3秒内CVP达谷值,Pinsky MR, Vincent JL, De Smet JM. Estimating left ventricular filling pressure during positive end-expiratory pressure in humans. Am Rev Respir Dis 1991; 143:2531,PEEP对CVP的影响 测定方法,Pinsky MR, Vincent JL, De Smet JM. Estimating left ventricular filling pressure during positive end-expiratory pressure in humans. Am Rev Respir Dis 1991; 143:2531,PEEP对CVP的影响 测定方法,优点,简单易行无需特殊设备,缺点,呼吸机条件高脱离呼吸机时可造成缺氧,顺应性的概念呼吸系统及肺,呼吸系统顺应性Crs = Vt / PalvPalv = Palv PEEP肺顺应性CL = Vt / (Palv ITP)胸廓顺应性CCW = Vt / ITP,1/Crs = 1/CL + 1/CCW,顺应性的概念呼吸系统及肺,Vt = CL x (Palv ITP)Vt = CCW x ITP,(Palv ITP) x CL = ITP x CCW,Palv x CL = ITP x (CCW + CL),ITP / Palv = CL / (CCW + CL),PEEP对ITP的影响,ITP/Palv = CL / (CL + CCW),OQuin R, Marini JJ: Pulmonary artery occlusion pressure: clinical physiology, measurement, and interpretation. Am Rev Respir Dis 1983, 128: 319-326,正常人CCW = CL = 0.2 cmH2O/L因此ITP/Palv = 1/2,PEEP对心脏前负荷的影响,Hassan FM, Weiss WB, Braman SS, et al. Influence of lung injury on pulmonary wedge-left atrial pressure correlation during positive end-expiratory pressure ventilation. Am Rev Respir Dis 131:246, 1985.,传递系数(Index of Transmission),IT = PAOP / Palv,Pplat PEEPtot,eePAOP eiPAOP,tPAOP = eePAOP PEEPtot x IT,Teboul JL, Pinsky MR, Mercat A, et al. Estimating cardiac filling pressure in mechanically ventilated patients with hyperinflation. Crit Care Med 2000; 28: 3631-3636,PEEP对前负荷的影响,Teboul JL, Pinsky MR, Mercat A, et al. Estimating cardiac filling pressure in mechanically ventilated patients with hyperinflation. Crit Care Med 2000; 28: 3631-3636,PEEP与前负荷顺应性的影响,Teboul JL, Pinsky MR, Mercat A, et al. Estimating cardiac filling pressure in mechanical