Protsenko D N, Boytsov P V, Chentsov V B, Nistratov S L, Kudlyakov O N, Solov'ev V V, Banova Zh I, Shkuratova N V, Rezenov N A, Gel'fand B R
Anesteziol Reanimatol. 2016 Nov;61(6):425-432.
to determine optimum level ofpositive end-expiratory pressure (PEEP) according to balance between maxi- mal end-expiratory lung volume (EEL V)(more than predicted) and minimal decrease in exhaled carbon dioxide volume (VCO) and then to develop the algorithm of gas exchange correction based on prognostic values of EEL K; alveolar recruitability, PA/FiO2, static compliance (C,,,) and VCO2.
27 mechanically ventilatedpatients with acute respiratory distress syndrome (ARDS) caused by influenza A (HINJ)pdm09 in Moscow Municipal Clinics ICU's from January to March 2016 were included in the trial. At the beginning of the study patients had the following characteristic: duration offlu symptoms 5 (3-10) days, p.0/FiO2 120 (70-50) mmHg. SOFA 7 (5-9), body mass index 30.1 (26.4-33.8) kg/m², static compliance of respiratory system 35 (30-40) ml/mbar: Under sedation and paralysis we measured EELV, C VCO and end-tidal carbon dioxide concentration (EtCO) (for CO₂ measurements we fixed short-term values after 2 min after PEEP level change) at PEEP 8, 11,13,15,18, 20 mbar consequently, and incase of good recruitability, at 22 and 24 mbar. After analyses of obtained data we determined PEEP value in which increase in EELV was maximal (more than predicted) and depression of VCO₂ was less than 20%, change in mean blood pressure and heart rate were both less than 20% (measured at PEEP 8 mbar). After that we set thus determined level of PEEP and didn't change it for 5 days.
Comparision of predicted and measured EELV revealed two typical points of alveloar recruiment: the first at PEEP 11-15 mbar, the second at PEEP 20-22 mbar. EELV measured at PEEP 18 mbar appeared to be higher than predicted at PEEP 8 mbar by 400 ml (approx.), which was the sign of alveolar recruitment-1536 (1020-1845) ml vs 1955 (1360-2320) ml, p=0,001, Friedman test). we didn't found significant changes of VCO₂ when increased PEEP in the range from 8 to 15 mbar (p>0.05, Friedman test). PEEP increase from 15 to 18 mbar and more lead to decrease in VCO₂ (from 212 (171-256) ml/min to 200 (153-227) ml/min, p<0,0001, Friedman test, which was the sign of overdistension. Next decrease of VCO₂ was observed at PEEP increase from 22 to 24 mbar (from 203 (174-251 ml/min) to 185 (182-257) ml/min, p=0.0025, Friedman test). Adjusted PEEP value according to balance between recruitment and overdistension was higher than the one initially set (16(15-18) mbar vs 12(7-15) mbar, p <0.0001). We observed increase of SpO₂ from 93 (87-96) to 97(95-100)% (p<0.0001 followed by decrease in inspiratory oxygen fraction from 60(40-80) to 50(40-60)%(p<0.0001). Low EELV VCO₂ and VCO₂/EtCO₂ at PEEP 8 mbar has low predictive value for death (AUROC 0,547, 0706 and 0.596, respectively).Absolute EELV value at PEEP 18 and 20 mbar were poor predictors of mortality (AUROC 0.61 and 0.65 respectively) Alveolar recruit ability was measured by subtraction of EELV at PEEP 20 and at PEEP II mbar - value below 575 ml was a good predictor of death (sensitivity 75%, specificity 88%, AUROC 0.81). Lowering of VCO₂ at PEEP 20 mbar to less than 207 ml/min was a marker of alveolar overdistension and associated with poor prognosis (sensitivity 83%, specificity 88%, AUROC 0,89). C has poor predictive value at PEEP 8 and 20 mbar (AUROC 0,58 and 0,74 respectively.
PEEP adjustment in ARDS due to influenza A (H1N1) pdm09 in accordance with balance between recruitment and overdistension (based on EELV and VCO measurements) can improve gas exchange, probably, not leading to right ventricular failure. This value of "balanced" PEEP is in the range between 15 and 18 mbar: Low lung recruitabiilty is associated with poor prognosis. Measurements of EELV and VCO₂ at PEEP 8 and 20 mbar can be used to make a decision on whether to keep "high" PEEP level or switch to extracorporeal membrane oxygenation in patient with ARDS due to influenza A (N1H1).
根据最大呼气末肺容积（EELV，超过预测值）与呼出二氧化碳量（VCO₂）的最小减少之间的平衡，确定呼气末正压（PEEP）的最佳水平，然后基于EELV的预后值、肺泡可复张性、PA/FiO₂、静态顺应性（Cst）和VCO₂制定气体交换校正算法。
纳入2016年1月至3月在莫斯科市立诊所重症监护病房由甲型H1N1pdm09流感引起的急性呼吸窘迫综合征（ARDS）且接受机械通气的27例患者。研究开始时患者具有以下特征：流感症状持续时间5（3 - 10）天，pO₂/FiO₂ 120（70 - 50）mmHg，序贯器官衰竭评估（SOFA）评分7（5 - 9），体重指数30.1（26.4 - 33.8）kg/m²，呼吸系统静态顺应性35（30 - 40）ml/mbar。在镇静和肌松状态下，依次在PEEP为8、11、13、15、18、20 mbar时测量EELV、Cst、VCO₂和呼气末二氧化碳浓度（EtCO₂）（对于CO₂测量，在PEEP水平改变后2分钟固定短期值），若可复张性良好，则在22和24 mbar时测量。分析所得数据后，确定EELV增加最大（超过预测值）且VCO₂降低小于20%、平均血压和心率变化均小于20%（在PEEP 8 mbar时测量）时的PEEP值。之后设定如此确定的PEEP水平并维持5天不变。
预测EELV与实测EELV的比较显示出两个典型的肺泡复张点：第一个在PEEP 11 - 15 mbar，第二个在PEEP 20 - 22 mbar。在PEEP 18 mbar时测量的EELV比在PEEP 8 mbar时预测值高约400 ml，这是肺泡复张的标志（1536（1020 - 1845）ml对1955（1360 - 2320）ml，p = 0.001，Friedman检验）。当PEEP在8至15 mbar范围内增加时，未发现VCO₂有显著变化（p>0.05，Friedman检验）。PEEP从15增加到18 mbar及更高时导致VCO₂降低（从212（171 - 256）ml/min降至200（153 - 227）ml/min，p<0.0001，Friedman检验），这是过度扩张的标志。在PEEP从22增加到24 mbar时观察到VCO₂进一步降低（从203（174 - 251）ml/min降至185（182 - 257）ml/min，p = 0.0025，Friedman检验）。根据复张与过度扩张之间的平衡调整后的PEEP值高于最初设定的值（16（15 - 18）mbar对12（7 - 15）mbar，p<0.0001）。我们观察到SpO₂从93（87 - 96）%增加到97（95 - 100）%（p<0.0001），随后吸入氧分数从60（40 - 80）%降至50（40 - 60）%（p<0.0001）。在PEEP 8 mbar时低EELV、VCO₂和VCO₂/EtCO₂对死亡的预测价值较低（受试者工作特征曲线下面积（AUROC）分别为0.547、0.706和0.596）。在PEEP 18和20 mbar时的绝对EELV值对死亡率的预测较差（AUROC分别为0.61和0.65）。通过计算PEEP 20 mbar和PEEP 11 mbar时的EELV差值来测量肺泡可复张性，差值低于575 ml是死亡的良好预测指标（敏感性75%，特异性88%，AUROC 0.81）。在PEEP 20 mbar时VCO₂降至低于207 ml/min是肺泡过度扩张的标志，且与预后不良相关（敏感性83%，特异性88%，AUROC 0.89）。在PEEP 8和20 mbar时Cst的预测价值较差（AUROC分别为0.58和0.74）。
对于甲型H1N1pdm09流感所致ARDS，根据复张与过度扩张之间的平衡（基于EELV和VCO₂测量）调整PEEP可改善气体交换，可能不会导致右心室衰竭。这种“平衡”PEEP值在15至18 mbar之间：低肺可复张性与预后不良相关。在PEEP 8和20 mbar时测量EELV和VCO₂可用于决定ARDS患者是维持“高”PEEP水平还是转为体外膜肺氧合。
