Barbas Carmen Sílvia Valente, de Matos Gustavo Faissol Janot, Okamoto Valdelis, Borges João Batista, Amato Marcelo Britto Passos, de Carvalho Carlos Roberto Ribeiro
Hospital das Clinicas-Universidade de São Paulo, Avenida Dr. Eneas de Carvalho Aguiar, 7 andar-sala 7079, CEP: 05403-000, São Paulo, Brazil.
Respir Care Clin N Am. 2003 Dec;9(4):401-18, vii. doi: 10.1016/s1078-5337(03)00032-7.
In the experimental setting, repeated derecruitments of the lungs of ARDS models accentuate lung injury during mechanical ventilation, whereas open lung concept strategies can attenuate the injury. In the clinical setting, recruitment manuevers that use a continuous positive airway pressure of 40 cmH2O for 40 secs improve oxygenation in patients with early ARDS who do not have an impairment in the chest wall. High intermittent positive end-expiratory pressure (PEEP), intermitent sighs, or high-pressure controlled ventilation improves short-term oxygenation in ARDS patients. Both conventional and electrical impedance thoracictomography studies at the clinical setting indicate that high PEEP associated with low levels of pressure control ventilation recruit the collapsed portions of the ARDS lungs and that adequate PEEP levels are necessary to keep the ARDS lungs opened allowing a more homogenous ventilation. High PEEP/low tidal volume ventilation was seen to reduce inflammatory mediators in both bronchoalveolar lavage and plasma, compared to low PEEP/high tidal volume ventilation, after 36 hours of mechanical ventilation in ARDS patients. Recruitment maneuvers that used continuous positive airway pressure levels of 35-40 cmH2O for 40 secs, with PEEP set at 2 cmH2O above the lower inflection point of the pressure-volume curve, and tidal volume < 6 mL/kg were associated with a 28-day intensive care unit survival rate of 62%. This contrasted with a survival rate of only 29% with conventional ventilation (defined as the lowest PEEP for acceptable oxygenation without hemodynamic impairment with a tidal volume of 12 mL/kg), without recruitment manuevers (number needed to treat = 3; p < 0.001). In the near future, thoracic computed tomography associated with high-performance monitoring of regional ventilation may be used at the bedside to determine the optimal mechanical ventilation of the ARDS keeping an opened lung with a homogenous ventilation.
在实验环境中，急性呼吸窘迫综合征（ARDS）模型肺的反复复张会加重机械通气期间的肺损伤，而肺开放策略可减轻这种损伤。在临床环境中，对胸壁无损伤的早期ARDS患者使用40 cmH₂O持续气道正压通气40秒的复张手法可改善氧合。高间歇性呼气末正压（PEEP）、间歇性叹息或高压控制通气可改善ARDS患者的短期氧合。临床环境中的传统和电阻抗胸部断层扫描研究均表明，与低水平压力控制通气相关的高PEEP可使ARDS肺的萎陷部分复张，且需要足够的PEEP水平来保持ARDS肺开放，以实现更均匀的通气。与低PEEP/高潮气量通气相比，在ARDS患者机械通气36小时后，高PEEP/低潮气量通气可降低支气管肺泡灌洗和血浆中的炎症介质。使用35 - 40 cmH₂O持续气道正压水平40秒、PEEP设置为高于压力-容积曲线下拐点2 cmH₂O且潮气量<6 mL/kg的复张手法，与28天重症监护病房生存率62%相关。这与传统通气（定义为在无血流动力学损害且潮气量为12 mL/kg的情况下可接受氧合的最低PEEP）且无复张手法的29%生存率形成对比（治疗所需人数=3；p<0.001）。在不久的将来，与区域通气的高性能监测相关的胸部计算机断层扫描可能会在床边用于确定ARDS的最佳机械通气，以保持肺开放并实现均匀通气。
