背景:仰卧位急性呼吸窘迫综合征(ARDS)患者的躯干倾斜由于其对呼吸生理学的影响而获得了科学兴趣,包括机械师,氧合,通风分布,和效率。由于呼吸系统顺应性降低,从平卧变为半卧卧会增加驾驶压力。位置调整还会降低CO2去除的通风效率,特别是在COVID-19相关ARDS(C-ARDS)中,提示可能的肺实质过度扩张。倾斜躯干会降低胸壁顺应性,在较小程度上,肺顺应性和经肺驱动压力,具有显著的血液动力学和气体交换影响。
方法:前瞻性,在CHU克莱蒙费朗的两个ICU中对早期ARDS患者进行了初步生理研究,法国。该方案涉及从30°半坐位(基线)到不同倾斜水平(0°,30°,60°,和90°),返回基线位置之前。测量包括潮气量,呼气末正压(PEEP),食管压力,和肺动脉导管数据。主要终点是通过垂直化程序的经肺驱动压力的变化。
结果:从2020年5月到2021年1月,包括30名患者。经肺驱动压力较基线略有增加(中位数和四分位距[IQR],9[5-11]cmH2O)到90°位置(10[7-14]cmH2O;对于混合模型中位置的整体影响,P<10-2)。呼气末肺容积随垂直化增加,同时减少肺泡应变和增加动脉氧合。垂直化与心输出量和每搏输出量下降有关,去甲肾上腺素剂量和血清乳酸水平增加,提示两名患者中断手术。没有其他不良事件,如跌倒或设备意外移除。
结论:在ARDS患者中,垂直至90°是可行的,改善EELV和氧合高达30°,可能是由于肺泡募集和血流重新分布。然而,超过30°存在过度扩张和血流动力学不稳定的风险,根据临床情况需要个性化的床角。试验注册ClinicalTrials.gov注册号NCT04371016,2020年4月24日。
BACKGROUND: Trunk inclination in patients with Acute Respiratory Distress Syndrome (ARDS) in the supine position has gained scientific interest due to its effects on respiratory physiology, including mechanics, oxygenation, ventilation distribution, and efficiency. Changing from flat supine to semi-recumbent increases driving pressure due to decreased respiratory system compliance. Positional adjustments also deteriorate ventilatory efficiency for CO2 removal, particularly in COVID-19-associated ARDS (C-ARDS), indicating likely lung parenchyma overdistension. Tilting the trunk reduces chest wall compliance and, to a lesser extent, lung compliance and transpulmonary driving pressure, with significant hemodynamic and gas exchange implications.
METHODS: A prospective, pilot physiological study was conducted on early ARDS patients in two ICUs at CHU Clermont-Ferrand, France. The protocol involved 30-min step gradual verticalization from a 30° semi-seated position (baseline) to different levels of inclination (0°, 30°, 60°, and 90°), before returning to the baseline position. Measurements included tidal volume, positive end-expiratory pressure (PEEP), esophageal pressures, and pulmonary artery catheter data. The primary endpoint was the variation in transpulmonary driving pressure through the verticalization procedure.
RESULTS: From May 2020 through January 2021, 30 patients were included. Transpulmonary driving pressure increased slightly from baseline (median and interquartile range [IQR], 9 [5-11] cmH2O) to the 90° position (10 [7-14] cmH2O; P < 10-2 for the overall effect of position in mixed model). End-expiratory lung volume increased with verticalization, in parallel to decreases in alveolar strain and increased arterial oxygenation. Verticalization was associated with decreased cardiac output and stroke volume, and increased norepinephrine doses and serum lactate levels, prompting interruption of the procedure in two patients. There were no other adverse events such as falls or equipment accidental removals.
CONCLUSIONS: Verticalization to 90° is feasible in ARDS patients, improving EELV and oxygenation up to 30°, likely due to alveolar recruitment and blood flow redistribution. However, there is a risk of overdistension and hemodynamic instability beyond 30°, necessitating individualized bed angles based on clinical situations. Trial registration ClinicalTrials.gov registration number NCT04371016 , April 24, 2020.