每日一题_2022.07.30

A 45-year-old man is admitted to the ICU after a 30-foot fall from a telephone pole while he was working. He sustained a traumatic subarachnoid hemorrhage, pulmonary contusions, grade II liver and kidney lacerations, and a broken right femur and acetabulum. He is intubated in the emergency department with a Glasgow Coma Scale (GCS) score of 12 and moderate hypoxia, with oxygen saturations of 88% on a nonrebreather mask. During the next two days his oxygenation worsens. Acute respiratory distress syndrome is suspected from the trauma and blossoming pulmonary contusions. He is heavily sedated, paralyzed with cisatracurium, and requires no intracranial pressure monitoring. Ventilator settings are: assist control/pressure control, respiratory rate 35 breaths/min, FIO2 100%, positive end-expiratory pressure (PEEP) 22 cm H2O, peak airway pressure 35 cm H2O. Tidal volumes are at 6 mL/kg predicted body weight. Most recent arterial blood gas analysis shows: pH 7.24, partial arterial carbon dioxide pressure 60 mm Hg, partial arterial oxygen pressure 50 mm Hg.

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

A. Start inhaled nitric oxide.

B. Increase respiratory rate to compensate for respiratory acidosis.

C. Increase PEEP to improve oxygenation.

D. Place the patient in prone position.

E. Change the ventilator mode to assist control/volume control and maintain FIO2 and PEEP.

答案解析：

在过去15年中，严重急性呼吸窘迫综合征 (ARDS) 领域有了巨大的进步。最重要的是，潮气量接近 6 mL/kg 预测体重的肺保护通气显著降低了患者死亡率。除此之外，关于其他也可能改善死亡率的辅助治疗一直存在很多争议。包括麻痹剂、最佳呼气末正压 (PEEP) 水平、吸入肺血管扩张剂（一氧化氮、依前列醇）、高频振荡通气、俯卧位等。

该患者在明显创伤后出现严重ARDS，尽管进行了最佳的呼吸机管理，但仍缺氧，动脉血氧分压为50 mmHg。此时，需要进一步的支持性措施来改善氧合。22 cm H2O 时的 PEEP 接近最大值，在气道峰压为 35 cm H2O 的压力控制通气下，进一步向上滴定可能使肺发生不必要的呼吸机相关肺损伤。ARDS 治疗中允许性高碳酸血症耐受性良好，pH值为7.24，呼吸频率为35次/min，不应进一步调整。没有单一通气模式被证明优于另一种模式；因此，改变模式以辅助控制/容量控制不太可能有帮助。常使用吸入型肺血管扩张剂如依前列醇、一氧化氮等，但尚无研究显示使用后死亡率下降。此外，一氧化氮可能与急性肾损伤相关，并且非常昂贵。在重度 ARDS 中，如果早期和长期进行俯卧位通气，已被证明可降低死亡率。无颅内压问题的患者蛛网膜下腔出血不是俯卧位通气的禁忌症。

正确答案：D