每日一题_2022.08.24

Two days ago, a man underwent cardiac bypass surgery with revascularization of three vessels and placement of a bioprosthetic aortic valve. His postoperative course was complicated by cardiogenic shock requiring inotropic support. He required transfusion of blood products postoperatively. He was extubated and transitioned to supplemental oxygen via nasal cannula. His inotropic support was weaned off. He experiences an acute hypoxic event and is in acute respiratory distress and is then intubated. In the peri-intubation period, he has a cardiac arrest. As part of the procedure, a continuous capnogram is placed in line with the endotracheal tube. Regarding end-tidal carbon dioxide (ETCO2), which of the following statements is true?

A. An esophageal intubation is always manifested with a flat ETCO2.

B. A decrease in ETCO2 can be caused by fever, hypoventilation, partial airway obstruction, and the use of sodium bicarbonate.

C. An increase in ETCO2 can be caused by hypothermia and hypovolemia.

D. An ETCO2 value of greater than 20 mm Hg is a reflection of poor-quality chest compressions.

E. A sudden increase in ETCO2 during chest compressions can be a sign of return of spontaneous circulation.

答案解析：

所有机械通气患者都应考虑使用定量二氧化碳图，因为它可以直接测量肺通气量。正常的 ETCO2 值
在一个健康的成年人中应该是 35 到 45 毫米汞柱。二氧化碳图间接提供新陈代谢和心输出量的测量。降低全身代谢、体温过低和循环量差的生理状态将在数值上反映为 ETCO2 的降低。相反，增加全身新陈代谢的生理状态，如发热，会体现为ETCO2的增加。减少的生理状态心输出量，例如肺栓塞，将反映为 ETCO2 的降低。药物干预，例如给予大量碳酸氢钠，几乎会立即反映在 ETCO2 的增加上，因为肺会补偿增加的 ETCO2二氧化碳负荷。定量二氧化碳图可以为气管插管提供确认信息。食管插管最初可能具有 ETCO2 波形。由于胃内二氧化碳迅速消失。定量的两种实际用途心肺复苏期间的二氧化碳图是：1) 评估胸外按​​压的有效性，以及 2) 识别自主循环 (ROSC) 的恢复。插管患者的 ETCO2 值在 10 到 20 mm Hg 之间反映了高质量的胸外按压。 ROSC 反映为 ETCO2 的自发显着增加（接近 35 mm Hg 的生理正常范围），因为心脏通过恢复节律来改善心输出量并将 CO2 循环到肺部。

正确答案：E