超声心动图指导下肺复张策略对中重度急性呼吸窘迫综合征患者血流动力学及心 功能的影响
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Moderate and Severe Acute Respiratory Distress Syndrome: Hemodynamic and Cardiac Effects of an Open Lung Strategy With Recruitment Maneuver Analyzed Using Echocardiography
背景与目的
肺复张⼿法的肺开放策略对急性呼吸窘迫综合征（ARDS）患者具有重要意义，但其可引起⽓道压⼒的升⾼并引发⼼脏功能障碍，从⽽限制其治疗效果。本研究探讨肺复张⼿法以及递减式呼⽓末正压通⽓（PEEP）对⼼脏功能的影响。
方 法
对确诊ARDS的20名患者施⾏逐步肺复张⼿法，同时进⾏呼吸评估和⼼功能的超声⼼动图评估。 肺复张开始时，将初始PEEP设置为25cmH2O，驱动压（DP）15cmH2O。然后以每2分钟5cmH2O的速度逐渐增加PEEP直⾄达到40 cmH2O（达到40 cm H2O时，持续时间为3到4分钟以记录超声⼼动图图像），同时保持15 cmH2O的DP。在PEEP达到峰值后，施加25cmH2O的PEEP和15cmH2O的DP，然后以每4分钟2cmH2O逐步减少PEEP。当氧饱和度或顺应性分别降低2或2mL/cmH2O时，终⽌PEEP⽔平的降低。当氧饱和度或顺应性分别降低2或2mL/cmH2O时，停⽌降低PEEP⽔平。⼀旦达到最低⽔平并确认减少氧合作⽤，则再次进⾏肺复张（重新进⾏肺开放），然后将PEEP直接降低到最低⽔平之前的PEEP⽔平，并将此⽔平指定为最佳PEEP⽔平，即最佳PEEP⽔平为⽐
最低PEEP⽔平⾼2cmH2O时的⽔平。
结 果
在施⾏肺复张⼿法呼⽓末正压达到峰值时，动脉压、⼼排⾎量、左⼼室容积减⼩，右⼼室容积增加。左⼼室射⾎分数从60%±13%降⾄48%±18%（p = 0.05）。左⼼室和右⼼室整体纵向应变均受损（分别为-15.8%±4.5%⾄-11%±4.7%和-19%±5%⾄-14%±6% [p = 0.05]）。最佳呼⽓末正压为14±5 cmH2O（基线时为11±4cmH2O）,PaO2/FiO2⽐值从111±25增加到197±89 mmHg（p <0.0001）。尽管有较⾼的呼⽓末正压，但在施⾏肺复张⼿法后所有⾎流动⼒学变量都恢复到其基线值。
结 论
逐步增加PEEP的肺复张策略有利于中重度ARDS患者氧合功能的改善；肺复张⼿法可产⽣轻度可逆的⼼脏功能障碍，但不会明显损伤⼼脏功能。
原始文献摘要
Mercado P, Maizel J, Kont ar L, et al. Moderat e and Severe Acute Respiratory Distress Syndrome: Hemodynamic and Cardiac Effects of an Open Lung Strategy With Recruitment Maneuver Analyzed Using Echocardiography. Crit Care Med. 2018 Oct ;46(10):1608-1616. doi: 10.1097/CCM.0000000000003287.
Objectives: Open lung ventilation with a recruitment maneuver could be beneficial for acute respiratory distress syndrome patients. However, the increased airway pressures resulting f rom the recruitment maneuver may induce cardiac
dysf unction, limiting the benefit of this maneuver. We analyzed the effect of a recruitment maneuver and decremental positive end-expiratory pressure titration on cardiac function.
Settings: Medical ICU Amiens, France.
Patients: Twenty patients with moderate to severe acute respiratory distress syndrome.
Interventions: Patients underwent a stepwise recruitment maneuver with respiratory evaluation and echocardiography assessment of cardiac function including longitudinal strain at baseline, peak positive end-expiratory pressure of recruitment maneuver (positive end-expiratory pressure 40 cm H2O), and at“optimal” positive end-expiratory pressure. The patients were divided into two groups based on change on the Pao2/Fio2 ratio (nonresponders< 50%; responders ≥ 50%).
Measurements and Main Results: At peak positive end-expiratory pressure during the recruitment maneuver, the arterial pressure,cardiac output, left ventricular size decreased and right ventricularsize increased. The left ventricular ejection fraction decreased f rom 60% ± 13% to 48% ± 18% (p =0.05). Both left and right ventricular global longitudinal strain were impaired (–15.8% ± 4.5% to –11% ± 4.7% and – 19% ± 5% to –14% ± 6% [p = 0.05] respectively). Fifty percent of patients were nonresponders and demonstrated a lower hemodynamic tolerance to the mrecruitment maneuver than responders. Optimal positive end-expiratory pressure was 14 ± 5cm H2O (vs 11 ± 4 cm H2O at baseline), and Pao2/Fio2 ratio increased f rom 111± 25 to 197 ± 89 mm Hg (p < 0.0001). All hemodynamic variables returned to their baseline value af ter the recruitment maneuver despite a higher positive endexpiratory pressure.
Conclusions: An open lung strategy with a stepwise recruitment maneuver permitted a higher positive end-expiratory pressure and improved oxygenation without any cardiac impairment. The recruitment maneuver was associated with mild and transient, cardiac dysf unction, with nonresponders demonstrating poorer tolerance.
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