ARDS呼吸功能监测与通气策略抉择.ppt

ARDS呼吸功能监测 与通气策略抉择 邱海波邱海波 刘玲刘玲 东南大学附属中大医院东南大学附属中大医院ICUICU 内容提要 Physiopathologic course of ARDS and the dilemma in Mechanical ventilation Oxygenation and Shunt Respiratory mechanics Compliance(Elastance)and Resistance Stress index Esophageal Pressure Vd/Vt Therapeutic target of MV in ARDS Become evident over the past two decades MV itself can augment or cause pulmonary damage Shift of therapeutic target of MV in ARDS 1970s Normal gas exchange 1980-1990 Protection of the lung from VILI N Engl J Med 1972;287:799-806.Lancet 1980;2:292-4.Am Rev Respir Dis 1987;135:312-5.Intensive Care Med 1990;16:372-7.The lung-protection strategy Lung recruitment-open the lung Use of higher PEEP-keep lung open(avoid collapse/recruitment)Low tidal volumes(Pplat 30cmH2O)-avoid overdistension Prevent regional and global stress and strain on the lung parenchyma Am J Respir Crit Care Med.2008,178:346355.Same MV strategy sutiable for every ARDS pat?May be No.Physiological effects of RM and PEEP associated with patients individual characteristics Inflamattion spreading from core disease Percentage of potentially recruitable lung Different stages of ARDS N Engl J Med.2006,354;1775-86.JAMA.1994,271,1772-79.Inflamattion spreading from core disease Possible model Lower Higher Higher severity mortality Core disease 24%Inflammation spreading 1 Lower severity mortality Potentially recruitable lung Lower percentage of potentially recruitable lung Higher percentage of potentially recruitable lung N Engl J Med.2006,354;1775-86 Mortality in Relation to the Percentage of potentially Recruitable Lung(Panel A)Pulmonary anatomy according to CT Findings in patients with Healthy Lungs,Patients with Unilateral Pneumonia,and Patients with Acute Lung Injury or ARDS(Panel B).N Engl J Med.2006,354;1775-86 Lower VS Higher percentage of potentially recruitable lung Higher percentage of potentially recruitable lung Greater total lung weights Poorer oxygenation Respiratory-system compliance Higher levels of dead space Higher rates of death N Engl J Med.2006,354;1775-86 Different stages of ARDS Pathologic stages Early exudative phase edema,bleeding,atelactasis,PMN and plt embolus,and microembolus Proliferative phase proliferation of tive II epithelium cell Fibrotic phase Proliferation of fibroblast Heterogeneity：location,time course Versatility:Pathologic changes Difficult to assess Gattinoni L(1994)Early ARDS(MV up to 1 week):prevalent edema Intermediate ARDS(between 12 weeks):a transition period during edema begins to be reabsorbed and proliferative processes begin to occur Late ARDS(more than 2 weeks):fibrous processes Clinical stages of ARDS JAMA.1994,271,1772-79.Early VS Late ARDS 84 sever ARDS for underwent extracoresl support(1979-1992)JAMA.1994,271,1772-79.EarlyEarlyInterInterLateLateMV L/minMV L/minRR b/mnRR b/mnPaCO2 mmHgPaCO2 mmHg0 01010202030304040505060607070MV L/minMV L/minRR b/mnRR b/mnPaCO2 mmHgPaCO2 mmHgEarly VS Late ARDS JAMA.1994,271,1772-79.0102030405060EarlyEarlyInterInterLateLate7071727374757677787980PEEPPEEPQs/QtQs/QtVd/VtVd/VtCT scan,early VS late ARDS Gattinoni L Type 1 Early ARDS Week 1 Intermediate ARDS Week 2 Late ARDS Week 7d)RM:PCV 2min at PIP 50cmH2O/PEEP PUIP Am J Respir Crit Care Med,2002,165:165170 Summary-Early and Late ARDS Early ARDS is characterized by edema and intact lung structure Recruitability is function of the extent of edema With time lung structure is altered associated with increased dead space and PCO2 Prognosis of ARDS Inflammation spreading Potentially recruitable lung Lower Lower severity mortality RM and higher PEEP may be harmful Higher Higher severity mortality RM and higher PEEP are needed Core disease Aggravated Improved Early ARDS Late ARDS Effect of RM and higher PEEP?Questions How to know who will get benefit from RM and PEEP How to set a suitable PEEP in ARDS patient CT scan may be one choice But not at bed side PaO2(P/F)may be another choice But our goal is not better gas exchange How about bedside respiratory mechanical monitoring Reduce VILI 内容提要 Physiopathologic course of ARDS and the dilemma in Mechanical ventilation Oxygenation and Shunt Respiratory mechanics Compliance(Elastance)and Resistance Stress index Esophageal Pressure Vd/Vt Shunt is the fundamental cause of hypoxemia in ARDS RM and PEEP Improve oxygenation(P/F)Reduced Shunt Am J Respir Crit Care Med,2001,164:1701-1711 肺泡完全复张的临床标准-P/F 1.PaO2/FiO2400 PaO2+PaCO2 400 2.PaO2/FiO2 降低降低5%PaO2+PaCO2 400(at 100%oxygen):维持肺开放的可靠指标维持肺开放的可靠指标 达到达到PaO2+PaCO2 400时：时：CT显示只有显示只有5%的肺泡塌陷的肺泡塌陷 PaO2+PaCO2 400对塌陷肺对塌陷肺泡的预测：泡的预测：ROC曲线下面积曲线下面积 0.943 Borges JB,Amato MBP.Am J Respir Crit Care Med Vol 174.pp 111,2006 肺泡完全复张的临床标准-CT 肺泡完全复张的临床标准肺泡完全复张的临床标准-CT Borges JB,Amato MBP.Am J Respir Crit Care Med Vol 174.pp 111,2006 动脉氧合与塌陷肺组织重量明显呈负相关动脉氧合与塌陷肺组织重量明显呈负相关(R=0.91)Methods of Qs/Qt calculation Qc:经肺毛细血管回心的血量(已气体交换)Qs:经短路回心的血量(未经体交换)Qt=Qc+Qs 总回心血量 计算公式：太复杂但比较准确 正常肺Qs/Qt 4-5%ARDS Qs/Qt常30%简化公式简化公式 吸空气时：吸纯氧时：应用条件 吸纯氧10-20min(最大限度纠正相对分流)PaO2150-200mmHg P/F and Qs/Qt