Institute of Anesthesiology and Resuscitation, Sacred Heart Catholic University, Rome, Italy -
Department of Emergency, Anesthesiology and Resuscitation Sciences, A. Gemelli University Polyclinic, IRCCS and Foundation, Rome, Italy -
Minerva Anestesiol. 2019 Sep;85(9):1014-1023. doi: 10.23736/S0375-9393.19.13418-9. Epub 2019 Mar 12.
The role of spontaneous breathing among patients with acute hypoxemic respiratory failure and ARDS is debated: while avoidance of intubation with noninvasive ventilation (NIV) or high-flow nasal cannula improves clinical outcome, treatment failure worsens mortality. Recent data suggest patient self-inflicted lung injury (P-SILI) as a possible mechanism aggravating lung damage in these patients. P-SILI is generated by intense inspiratory effort yielding: (A) swings in transpulmonary pressure (i.e. lung stress) causing the inflation of big volumes in an aerated compartment markedly reduced by the disease-induced aeration loss; (B) abnormal increases in transvascular pressure, favouring negative-pressure pulmonary edema; (C) an intra-tidal shift of gas between different lung zones, generated by different transmission of muscular force (i.e. pendelluft); (D) diaphragm injury. Experimental data suggest that not all subjects are exposed to the development of P-SILI: patients with a PaO2/FiO2 ratio below 200 mmHg may represent the most at risk population. For them, current evidence indicates that high-flow nasal cannula alone may be superior to intermittent sessions of low-PEEP NIV delivered through face mask, while continuous high-PEEP helmet NIV likely promotes treatment success and may mitigate lung injury. The optimal initial noninvasive treatment of hypoxemic respiratory failure/ARDS remains however uncertain; high-flow nasal cannula and high-PEEP helmet NIV are promising tools to enhance success of the approach, but the best balance between these techniques has yet to be identified. During noninvasive support, careful clinical monitoring remains mandatory for prompt detection of treatment failure, in order not to delay intubation and protective ventilation.
在急性低氧性呼吸衰竭和 ARDS 患者中，自主呼吸的作用存在争议：虽然避免使用无创通气（NIV）或高流量鼻导管进行插管可改善临床结局，但治疗失败会使死亡率恶化。最近的数据表明，患者自身造成的肺损伤（P-SILI）可能是加重这些患者肺损伤的一种机制。P-SILI 是由强烈的吸气努力产生的：（A）跨肺压（即肺应力）的波动导致充气量大幅增加，而疾病引起的通气损失显著减少了充气量；（B）跨血管压的异常增加，有利于负压性肺水肿；（C）不同肺区之间的气体在潮气量内的转移，由肌肉力量的不同传递（即 pendelluft）引起；（D）膈肌损伤。实验数据表明，并非所有患者都有发生 P-SILI 的风险：PaO2/FiO2 比值低于 200 mmHg 的患者可能是最危险的人群。对于这些患者，目前的证据表明，高流量鼻导管单独使用可能优于通过面罩间歇性进行低 PEEP 的 NIV，而持续高 PEEP 头盔式 NIV 可能更有助于治疗成功，并可能减轻肺损伤。然而，低氧性呼吸衰竭/ARDS 的初始无创治疗最佳方案仍不确定；高流量鼻导管和高 PEEP 头盔式 NIV 是提高该方法成功率的有前途的工具，但这些技术之间的最佳平衡仍有待确定。在无创支持期间，仍需要仔细进行临床监测，以便及时发现治疗失败，从而避免延迟插管和保护性通气。
