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1、ARDS呼吸功能监测与通气策略抉择,邱海波 刘玲东南大学附属中大医院ICU,内容提要,Physiopathologic course of ARDS and the dilemma in Mechanical ventilationOxygenation and ShuntRespiratory mechanicsCompliance (Elastance) and ResistanceStress indexEsophageal PressureVd / Vt,Therapeutic target of MV in ARDS,Become evident over the past two
2、decadesMV itself can augment or cause pulmonary damage,Shift of therapeutic target of MV in ARDS,1970sNormal gas exchange,1980-1990Protection of thelung 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-protectio
3、n 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 sutiabl
4、e for every ARDS pat ?,May be No.Physiological effects of RM and PEEP associated with patients individual characteristics Inflamattion spreading from core diseasePercentage of potentially recruitable lungDifferent stages of ARDS,N Engl J Med. 2006, 354; 1775-86 .JAMA. 1994, 271, 1772-79.,Inflamattio
5、n spreading from core disease,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
6、 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 lungGreater total lung we
7、ights Poorer oxygenation Respiratory-system compliance Higher levels of dead spaceHigher 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 microembolusProliferative phase proliferati
8、on of tive II epithelium cellFibrotic phase Proliferation of fibroblast,Heterogeneity ：location, time courseVersatility : Pathologic changes,Difficult to assessGattinoni L (1994)Early ARDS (MV up to 1 week): prevalent edemaIntermediate ARDS (between 12 weeks): a transition period during edema begins
9、 to be reabsorbed and proliferative processes begin to occurLate 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.,Early VS Late ARDS,JAMA. 1994, 271,
10、1772-79.,CT scan, early VS late ARDS,Gattinoni L,Type 1,Early ARDSWeek 1,Intermediate ARDSWeek 2,Late ARDSWeek =3,Type 2,Early and Late- Recruitability,N=17 ARDS with a lung protective ventEarly ARDS (n=9) vs Late ARDS (n=8, 7d)RM: PCV 2min at PIP 50cmH2O/PEEP PUIP,Am J Respir Crit Care Med, 2002, 1
11、65:165170,Summary-Early and Late ARDS,Early ARDS is characterized by edema and intact lung structureRecruitability is function of the extent of edemaWith time lung structure is altered associated with increased dead space and PCO2,Prognosis of ARDS,Inflammation spreadingPotentially recruitable lung,
12、LowerLower severity mortalityRM and higher PEEP may be harmful,HigherHigher severity mortalityRM 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 PEEPHow to set a suitable PEEP in ARD
13、S patientCT scan may be one choiceBut not at bed sidePaO2 (P/F) may be another choiceBut our goal is not better gas exchangeHow about bedside respiratory mechanical monitoring,Reduce VILI,内容提要,Physiopathologic course of ARDS and the dilemma in Mechanical ventilationOxygenation and ShuntRespiratory m
14、echanicsCompliance (Elastance) and ResistanceStress indexEsophageal PressureVd / Vt,Shunt is the fundamental cause of hypoxemia in ARDS,RM 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/F,PaO2/FiO2400 PaO2 + PaCO2 400 2.PaO2/FiO2 降低5%,PaO2
15、+ PaCO2 400 (at 100% oxygen): 维持肺开放的可靠指标达到PaO2 + PaCO2 400时： CT显示只有5% 的肺泡塌陷 PaO2 + PaCO2 400对塌陷肺泡的预测： ROC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-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
16、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,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 change with lung recruitment,Case 63 Y woman Guillain-Barre Syndrome, Pneumonia, A
17、LI,PEEP,PEEP,内容提要,Physiopathologic course of ARDS and the dilemma in Mechanical ventilationOxygenation and ShuntRespiratory mechanicsCompliance (Elastance) and ResistanceStress indexEsophageal PressureVd / Vt,Respiratory mechanics -Compliance (Elastance) and Resistance,Concepts and Formula,E=P / Vol
18、C= Vol / PCst=Vt / (Pplat-PEEPtot)Cdyn=Vt / (PIP-PEEPtot)R= P / V,C= 1 / E,Compliance and Resistance changes in ARDS,Compliance decreased significantlyResistance may increase slightly,Compliance decreasedDue to alveolar collapse,Resistance increased,Compliance decreasedP-V curve,Reduced range of vol
19、ume excursion: Low complianceFlattening at low and high volumes: Lower and upper inflection points,Volume,Pressure,NORMAL,ARDS,顺应性曲线明显向右下移位,six pigletsvenous infusion of oleic acidPEEP titration (from 26 to 0 cmH2Owith a Vt of 6 to 7 ml/kg) performed, following a RM,Critical Care 2007, 11: R86.,Roni
20、toring respiratory mechanics during a PEEP titration procedure may be a useful adjunct to optimize lung aeration,Critical Care 2007, 11: R86.,PEEP at min Ers corresponded to the greatest amount of normally aerated areas,%E2: Percentage of volume dependent elastancePercentage of non-linearity of the
21、elastance of the Ers%E230%: tidal overdistension,Intensive Care Med. 2008, 34:22912299,In non-injured animals,Stress index and %E2 are useful in non-injured lungs onlyErs can be superior to the stress index and %E2 to guide PEEP titration in focal loss of lung aeration,Ers seems to be useful for gui
22、ding PEEP titration in non-injured and injured lungs,Female pigsLung lavageCrs: computed using the occlusion techniqueRM: 45 cmH2O for 40 sPeep10 cmH2OPro and Post RM (CT scan)Gas exchange Lung mechanics Amount and the changes in aerated and,Critical Care. 2005, 9: R471-R482,Vpoor: volume of poorly
23、aerated lung; Vhap: volume of hyperinflated lungPmcd: pressure of maximum compliance decrease on inflation curve,Crs may be useful for guiding PEEP titration,Changes in aerated and nonaerated lung volumes were adequately represented by Crs Not by changes in oxygenation or shunt,Critical Care. 2005,
24、9: R471-R482,Case,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 (P/F400 mm Hg or change10%) Set PEEP 20 cmH2O Reduce PEEP 2 cmH2O step by stepCrs: computed u
25、sing the occlusion technique,Not routinely RM?; PEEP 10 or 8 cmH2O?; VT 500ml,PEEP,PEEP,Respiratory mechanics -Stress index,Stress index,P=a * tb + c,VCV Constancy flow,Slutsky AS, Aneathiology, 2000,93: 1320-8 Grasso S, Crit Care Med, 2004, 32: 101827,Crit Care Med, 2004, 32: 101827,Precondition,RM
26、 Constancy flow,Crit Care Med, 2004, 32: 101827,How to do it at the bed side,Change to VCV (Constancy flow)Sedation (if necessary)RMSet a higher PEEP (eg 20 cm H2O)Reduce PEEP step by step (2-3cmH2O) and eye-measurement bRecord the PEEPs in b1-b=1-b1RM again set the PEEP in b=1,Case,64 y, man, 70 kg
27、 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 change10%) Set PEEP 18 cmH2O Reduce PEEP 3 cmH2O step by stepEye-measurement b,RMSIMV+PS (auto
28、flow), Vt 400ml, PEEP14 cmH2O, FiO2 50%, RR 24 b/minPplat 28 cm H2O, PaCO2 45 mmHg, P/F 339 Suitable?,Respiratory mechanics -MV Guided by Esophageal Pressure,MV Guided by Esophageal Pressurein ALI,Esophageal pressurepleuralpressure pressureTranspulmonary pressure= pulmonary alveolar pressure -Esopha
29、geal pressure61 ARDS pats MVControl or esophagealpressureguided groupPrimary end pointimprovement in oxygenationSecondary end points:Respiratory-system compliancePatient outcomes,N Engl J Med. 2008, 359; 2095,As compared with the current standard of careSignificantly improves oxygenation and complia
30、nce,N Engl J Med. 2008, 359; 2095,MV Guided by Esophageal Pressure,内容提要,Physiopathologic course of ARDS and the dilemma in Mechanical ventilationOxygenation and ShuntRespiratory mechanicsCompliance (Elastance) and ResistanceStress indexEsophageal PressureVd / Vt,Vd/Vt VS PEEP,生理死腔与潮气量比率（Vd/Vt） 是肺泡通气
31、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 outcomeMortality before hospital dis
32、charge,N Engl J Med. 2002, 346: 1281.,Increased Vd/Vt is a feature of the early phase of the ARDSElevated values are associated with an increased risk of death,N Engl J Med. 2002, 346: 1281.,Case 1Pat did not need higher PEEP,75y ManPneumonia ARDS diabetesICU day 1,Not routinely RMPEEP set 6 cmH2O,RM 后逐步降低PEEP水平Douglas气囊法可计算 Vd/Vt,Case 2Pat need higher PEEP,47y Man TraumaICU day 1,Routinely RM PEEP set 14 cmH2O,
