每日一题_2022.4.22

A man presents to the emergency department in a postictal state after a witnessed seizure. Five minutes after arrival, he has another tonic-clonic seizure that is difficult to control with antiseizure drugs. He is given benzodiazepines followed by phenytoin and remains in status epilepticus. There is concern that he may need an infusion of phenobarbital or propofol. Because of concerns for airway protection, he is successfully intubated. He is monitored with continuous EEG, and control of his seizure activity is obtained with a propofol infusion. Laboratory testing and imaging studies are obtained. Arterial blood gas analysis is pending. The bedside nurse reports that the continuous end-tidal carbon dioxide monitor alarm is sounding, with a value of 22 mm Hg. There have been no issues with hypoxia.

Which of the following is the best immediate next step?

A. Increase the set positive end-expiratory pressure to 10 mm Hg.

B. Ignore the alarm because this is within the physiologic normal end-tidal carbon dioxide range for a patient receiving positive-pressure ventilation and sedated with propofol.

C. Wait for laboratory results.

D. Decrease the respiratory rate.

E. Add dead space to the ventilator circuit.

答案解析：

对持续惊厥的癫痫持续状态患者气道的正确评估和管理可能是困难的。大多数患者将发生严重的代谢性酸中毒（与动脉pH < 7.0一样严重），并尝试呼吸代偿。癫痫持续状态的患者只要气道保持通畅，就继续用适当的气体交换进行呼吸。一旦癫痫发作得到控制，这种代谢性酸中毒将自行纠正。具有镇静副作用的抗癫痫药物可阻碍呼吸代偿的驱动，产生继发性酸碱紊乱（总体酸中毒恶化）伴呼吸性酸中毒。这种呼吸补偿是至关重要的，因为患者被置于呼吸机上，临床医生应计划高分钟通气需求。该患者无氧合问题，增加呼气末正压不是增加通气的正确干预。丙泊酚是一种镇静药物，通常会阻碍呼吸驱动，导致二氧化碳水平升高。降低设定的呼吸频率可能会恶化呼吸性酸中毒，对临床情况产生负面影响。死腔是通过将测量的呼气二氧化碳与仍有待进行的血气测量相关联来计算的；然而，该呼气末二氧化碳值与死腔问题并不一致。

正确答案：C