1、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 / VtTherapeutic target of MV in ARDS Become evid
2、ent over the past two decades MV itself can augment or cause pulmonary damageShift of therapeutic target of MV in ARDS 1970sNormal gas exchange1980-1990Protection of thelung from VILIN 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.
3、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 parenchymaAm J Respir Crit Care Med. 2008, 178: 346355.Same MV
4、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 ARDSN Engl J Med. 2006, 354; 1775-86 .JAMA. 1994, 271, 17
5、72-79. Inflamattion spreading from core diseasePossible modelLowerHigherHigher severity mortalityCore disease 24%Inflammation spreading 1Lower severity mortalityPotentially recruitable lungLower percentage of potentially recruitable lungHigher percentage of potentially recruitable lungN Engl J Med.
6、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; 1775-86Low
7、er 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 deathN Engl J Med. 2006, 354; 1775-86Different stages of ARDS Pathologic s
8、tagesEarly exudative phase edema, bleeding, atelactasis, PMN and plt embolus, and microembolusProliferative phase proliferation of tive II epithelium cellFibrotic phase Proliferation of fibroblastHeterogeneity ：location, time courseVersatility : Pathologic changes Difficult to assess Gattinoni L (19
9、94) 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 processesClinical stages of ARDSJAMA. 1994, 271, 1772-79. Early VS Late A
10、RDS 84 sever ARDS for underwent extracoresl support (1979-1992)JAMA. 1994, 271, 1772-79. Early VS Late ARDS JAMA. 1994, 271, 1772-79. CT scan, early VS late ARDS Gattinoni L Type 1Early ARDSWeek 1Intermediate ARDSWeek 2Late ARDSWeek 7d) RM: PCV 2min at PIP 50cmH2O/PEEP PUIPAm J Respir Crit Care Med,
11、 2002, 165:165170Summary-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 PCO2Prognosis of ARDSInflammation spreadingPotentially recruitabl
12、e lungLowerLower severity mortalityRM and higher PEEP may be harmfulHigherHigher severity mortalityRM and higher PEEP are neededCore diseaseAggravated Improved Early ARDSLate ARDSEffect of RM and higher PEEP?Questions How to know who will get benefit from RM and PEEP How to set a suitable PEEP in AR
13、DS 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 Respir
14、atory mechanics Compliance (Elastance) and Resistance Stress index Esophageal Pressure Vd / VtShunt is the fundamental cause of hypoxemia in ARDSRM and PEEPImprove 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/F1. PaO2/FiO2400 PaO2 + PaCO2 400 2.PaO2/FiO2
15、降低降低5%lPaO2 + 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l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l 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 0.943Borges 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-CTBorges JB, , Amato MBP.A
16、m J Respir Crit Care Med Vol 174. pp 111, 2006l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) PaO2150-200mmHgP/F and Qs/
17、Qt change with lung recruitment Case 63 Y woman Guillain-Barre Syndrome, Pneumonia, ALIPEEPPEEP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 / VtResp
18、iratory mechanics -Compliance (Elastance) and ResistanceConcepts and Formula E=P / Vol C= Vol / P Cst=Vt / (Pplat-PEEPtot) Cdyn=Vt / (PIP-PEEPtot) R= P / VC= 1 / ECompliance and Resistance changes in ARDS Compliance decreased significantly Resistance may increase slightlyCompliance decreasedDue to a
19、lveolar collapse Resistance increasedCompliance decreasedP-V curve Reduced range of volume excursion: Low compliance Flattening at low and high volumes: Lower and upper inflection pointsVolumePressureNORMALARDS顺应性曲线明显向右下移位顺应性曲线明显向右下移位 six piglets venous infusion of oleic acid PEEP titration (from 26
20、 to 0 cmH2O with a Vt of 6 to 7 ml/kg) performed, following a RMCritical Care 2007, 11: R86. Ronitoring respiratory mechanics during a PEEP titration procedure may be a useful adjunct to optimize lung aerationCritical Care 2007, 11: R86.PEEP at min Ers corresponded to the greatest amount of normally
21、 aerated areas %E2: Percentage of volume dependent elastance Percentage of non-linearity of the elastance of the Ers %E230%: tidal overdistensionIntensive Care Med. 2008, 34:22912299In non-injured animalsStress index and %E2 are useful in non-injured lungs onlyErs can be superior to the stress index
22、 and %E2 to guide PEEP titration in focal loss of lung aerationErs seems to be useful for guiding PEEP titration in non-injured and injured lungs Female pigs Lung lavage Crs: computed using the occlusion technique RM: 45 cmH2O for 40 s Peep10 cmH2O Pro and Post RM (CT scan) Gas exchange Lung mechani
23、cs Amount and the changes in aerated andCritical Care. 2005, 9: R471-R482Vpoor: volume of poorly aerated lung; Vhap: volume of hyperinflated lungPmcd: pressure of maximum compliance decrease on inflation curve Crs may be useful for guiding PEEP titrationChanges in aerated and nonaerated lung volumes
24、 were adequately represented by Crs Not by changes in oxygenation or shuntCritical Care. 2005, 9: R471-R482Case 79 y, man, 75 kg Pneumonia, ARDS, APACH II 27Sedation and nerve block Baiseline: VcV, Vt 500ml, PEEP 6cmH2O, RR 20 b/min, P/F Crs 56, Pplat 16cm H2O, PaCO2 35mmHg, P/F 121RM: SI 40cmH2O30s
25、 (P/F400 mm Hg or change1-b=1-b1 RM again set the PEEP in b=1Case64 y, man, 70 kg Multiple trauma, ARDSBaiseline MV set: SIMV+PS (autoflow), Vt 420ml, PEEP10cmH2O, FiO2 50%, RR 20 b/minPplat 26cm H2O, PaCO2 47mmHg, P/F 155Change to VCV: VT 420ml, RR 20 b/minRM: SI 40cmH2O30s (P/F400 or change1341513
26、16122Respiratory mechanics -MV Guided by Esophageal PressureMV Guided by Esophageal Pressurein ALI Esophageal pressurepleuralpressure pressure Transpulmonary pressure = pulmonary alveolar pressure -Esophageal pressure 61 ARDS pats MV Control or esophagealpressureguided group Primary end point improv
27、ement in oxygenation Secondary end points: Respiratory-system compliance Patient outcomesN Engl J Med. 2008, 359; 2095 As compared with the current standard of care Significantly improves oxygenation and complianceN Engl J Med. 2008, 359; 2095MV Guided by Esophageal Pressure内容提要 Physiopathologic cou
28、rse of ARDS and the dilemma in Mechanical ventilation Oxygenation and Shunt Respiratory mechanics Compliance (Elastance) and Resistance Stress index Esophageal Pressure Vd / VtVd/Vt VS PEEP 生理死腔与潮气量比率（Vd/Vt） 是肺泡通气效率的指标 过高的PEEP可能导致肺泡过度膨胀(Vd/Vt增加) 以往PEEP选择方法很少关注Vd/Vt问题 Vd/Vt可能用于指导ARDS患者PEEP的选择 Vd/Vt测定
29、方法测定方法 Douglas气囊法是最经典的方法 VCV 镇静和肌松 收集连续多个呼吸周期的呼出气于Douglas囊内 测定混合呼出气的CO2分压 通过Enghoff改进后Bohr方程计算 VDVT=(PaCO2PeCO2)PaCO2 Vd/Vt as a risk factor for death in ARDS 179 intubated ARDS pats, Study outcome Mortality before hospital dischargeN Engl J Med. 2002, 346: 1281. Increased Vd/Vt is a feature of the
30、early phase of the ARDS Elevated values are associated with an increased risk of deathN Engl J Med. 2002, 346: 1281.Case 1Pat did not need higher PEEP 75y Man Pneumonia ARDS diabetes ICU day 1 Not routinely RM PEEP set 6 cmH2O RM 后逐步降低后逐步降低PEEP水平水平 Douglas气囊法可计算气囊法可计算 Vd/VtCase 2Pat need higher PEEP 47y Man Trauma ICU day 1 Routinely RM PEEP set 14 cmH2O
