每日一题_2022.06.27

A 32-year-old man with 55% total body surface area non-circumferential burns remains mechanically ventilated in the ICU four days after injury. Overnight his oxygen requirements increased due to hypoxemia; pulse oximetry is currently 88%. His mechanical ventilator is set on assist control/volume control with tidal volume 420 mL, respiratory rate 20 breaths/min, positive end-expiratory pressure (PEEP) 12.5 cm H2O, and fraction of inspired oxygen (FIO2) 80%. Arterial blood gas analysis shows partial arterial oxygen pressure of 52 mm Hg. On an inspiratory pause maneuver, plateau airway pressure is 29 cm H2O. Chest radiograph shows bilateral pulmonary opacities. He has no known history of heart disease, and his predicted body weight is 70 kg (154.3 lb). The clinician is concerned about his refractory hypoxemia. 

Which of the following is the most appropriate next step in management?

A. Start inhaled nitric oxide at a concentration of 20 ppm; wean the FIO2 as tolerated.

B. Increase the set PEEP to 15 cm H2O.

C. Initiate venovenous extracorporeal membrane oxygenation

D. Initiate high-frequency oscillatory ventilation at an initial set mean airway pressure of 35 cm H2O; wean the FIO2 as tolerated.

E. Prone the patient with a goal of 16 hours of prone time regardless of facial edema.

答案解析：

该患者患有严重急性呼吸窘迫综合征(ARDS)，基于部分动脉血氧分压-吸入氧分数比小于100。文献中已经涵盖了难治性低氧血症的各种干预措施，例如1）使用专门的呼吸机肺复张操作进行肺泡复张，2）遵循呼气末正压(PEEP)表增加平均气道压，3）开放肺通气策略，如气道压力释放通气，4）吸入肺血管扩张剂以帮助通气/灌注不匹配，5）麻痹性输注，和6）俯卧位。最近，Guerin等人表明，在严重ARDS早期应用俯卧位可使死亡率的绝对风险降低约16%。他们的策略是早期、稳定期后和每天至少16小时应用俯卧位。他们的数据显示，研究组之间的并发症发生率没有差异，包括拔管。OSCILLATE试验研究者显示，早期应用高流量振荡器通气，中重度ARDS死亡率增加。该患者的平台压已经达到29 mm H2O。将PEEP增加至15 cm H2O将具有将其pleateau压力推至30 cm H2O以上的作用，除非依从性随着PEEP的增加而改善，并且既往ARDS数据显示，当平台压力维持在30 cm H2O以上时，死亡率增加。转诊至能够提供静脉-静脉体外膜肺氧合(ECMO)的中心显示可降低重度ARDS的死亡率，但在开始ECMO前有几种潜在的治疗。已证明吸入一氧化氮可改善氧合，但不能改善结局，且与肾损伤相关。

正确答案：E