Wilcox Susan R, Condella Anna
Massachusetts General Hospital, Boston, Massachusetts; Harvard Medical School, Boston, Massachusetts.
Massachusetts General Hospital, Boston, Massachusetts; Brigham and Women's Hospital, Boston, Massachusetts.
J Emerg Med. 2021 Jun;60(6):729-742. doi: 10.1016/j.jemermed.2020.12.014. Epub 2020 Dec 25.
While emergency physicians are familiar with the management of hypoxemic respiratory failure, management of mechanical ventilation and advanced therapies for oxygenation in the emergency department have become essential during the coronavirus disease 2019 (COVID-19) pandemic.
We review the current evidence on hypoxemia in COVID-19 and place it in the context of known evidence-based management of hypoxemic respiratory failure in the emergency department.
COVID-19 causes mortality primarily through the development of acute respiratory distress syndrome (ARDS), with hypoxemia arising from shunt, a mismatch of ventilation and perfusion. Management of patients developing ARDS should focus on mitigating derecruitment and avoiding volutrauma or barotrauma.
High flow nasal cannula and noninvasive positive pressure ventilation have a more limited role in COVID-19 because of the risk of aerosolization and minimal benefit in severe cases, but can be considered. Stable patients who can tolerate repositioning should be placed in a prone position while awake. Once intubated, patients should be managed with ventilation strategies appropriate for ARDS, including targeting lung-protective volumes and low pressures. Increasing positive end-expiratory pressure can be beneficial. Inhaled pulmonary vasodilators do not decrease mortality but may be given to improve refractory hypoxemia. Prone positioning of intubated patients is associated with a mortality reduction in ARDS and can be considered for patients with persistent hypoxemia. Neuromuscular blockade should also be administered in patients who remain dyssynchronous with the ventilator despite adequate sedation. Finally, patients with refractory severe hypoxemic respiratory failure in COVID-19 should be considered for venovenous extracorporeal membrane oxygenation.
虽然急诊医生熟悉低氧性呼吸衰竭的管理，但在2019冠状病毒病（COVID-19）大流行期间，急诊科的机械通气管理和先进的氧合治疗已变得至关重要。
我们回顾了目前关于COVID-19低氧血症的证据，并将其置于急诊科已知的基于证据的低氧性呼吸衰竭管理背景下。
COVID-19主要通过急性呼吸窘迫综合征（ARDS）导致死亡，低氧血症由分流引起，即通气与灌注不匹配。对发生ARDS的患者进行管理应侧重于减轻肺不张并避免容积伤或气压伤。
由于存在气溶胶化风险且在重症病例中获益有限，高流量鼻导管吸氧和无创正压通气在COVID-19中的作用较为有限，但可予以考虑。能够耐受体位改变的稳定患者在清醒时应采取俯卧位。一旦插管，患者应采用适合ARDS的通气策略进行管理，包括设定肺保护性潮气量和低压。增加呼气末正压可能有益。吸入性肺血管扩张剂虽不会降低死亡率，但可用于改善难治性低氧血症。插管患者采用俯卧位与ARDS死亡率降低相关，对于持续低氧血症的患者可予以考虑。对于尽管给予充分镇静但仍与呼吸机不同步的患者，也应给予神经肌肉阻滞剂。最后，对于COVID-19中难治性严重低氧性呼吸衰竭患者，应考虑进行静脉-静脉体外膜肺氧合。
