Rationale: No systematic investigation into dyspnea in patients receiving prolonged ventilation (>21 d) after recovering from critical illness has been published. Objectives: We sought to determine the magnitude, nature, and pathophysiological basis of dyspnea during an unassisted-breathing trial in patients receiving prolonged ventilation. Methods: Dyspnea intensity and descriptor selection were investigated in 27 patients receiving prolonged ventilation during a 60-minute unassisted-breathing trial. Pressure-time product, respiratory mechanics, and PtcCO2 were also measured. Measurements and Main Results: Of 10 patients who reported dyspnea during assist-control ventilation, 9 (90.0%) selected "Not getting enough air" to characterize dyspnea. Vt setting was lower in dyspneic than in nondyspneic patients (480.0 vs. 559.4 ml), P < 0.046. During the unassisted-breathing trial (n = 26), patients developed increases in dyspnea (P < 0.01) and PtcCO2 (P < 0.01) but no change in [Formula: see text]e. Dyspnea score was strongly linked to PtcCO2 (P < 0.012) and airway resistance (P < 0.013) but not respiratory work (although pressure-time product was almost three times higher than normal). At 60 minutes into the trial, 83.3% of patients selected "Not getting enough air" on its own or in combination with "Too much effort" to describe discomfort, whereas only 16.7% selected "Too much effort" on its own (P < 0.001). Across the dyspnea spectrum, patients chose "Not getting enough air" overwhelmingly over other descriptor options (P < 0.001). Conclusions: Patients developed increases in dyspnea and PtcCO2 but unchanged [Formula: see text]e and work of breathing during an unassisted-breathing trial; patients selected air-hunger descriptors overwhelmingly over excessive effort. The observations support the belief that air hunger results from heightened respiratory center stimulation combined with the incapacity to increase [Formula: see text]e.

中文翻译：

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空气饥饿远远超过机械通气和脱机试验期间的呼吸困难努力感。


理由：尚未发表对危重疾病恢复后接受延长通气的患者 （>21 d） 呼吸困难的系统调查。研究目的：我们试图确定在接受长时间通气的患者进行无辅助呼吸试验期间呼吸困难的程度、性质和病理生理学基础。方法： 在 60 分钟的无辅助呼吸试验中，调查了 27 例接受延长通气的患者的呼吸困难强度和描述符选择。还测量了压力时间乘积、呼吸力学和 PtcCO2。测量和主要结果： 在报告辅助控制通气期间呼吸困难的 10 名患者中，9 名 （90.0%） 选择“空气不足”来描述呼吸困难。呼吸困难患者的 Vt 设置低于非呼吸困难患者 （480.0 vs. 559.4 ml），P < 0.046。在无辅助呼吸试验 （n = 26） 期间，患者出现呼吸困难 （P < 0.01） 和 PtcCO2 （P < 0.01） 增加，但 [公式： 见正文] e 没有变化。呼吸困难评分与 PtcCO2 （P < 0.012） 和气道阻力 （P < 0.013） 密切相关，但与呼吸功无关 （尽管压力时间乘积几乎比正常值高三倍）。在试验进行 60 分钟时，83.3% 的患者选择了 “没有得到足够的空气” 或与 “太努力 ”相结合来描述不适，而只有 16.7% 的患者选择了 “太多努力” 单独出现 （P < 0.001）。在整个呼吸困难谱系中，患者压倒性地选择了“没有得到足够的空气”而不是其他描述符选项 （P < 0.001）。 结论：患者在无辅助呼吸试验期间呼吸困难和 PtcCO2 增加，但没有变化 [公式：见正文]e 和呼吸功;患者绝大多数选择了空气饥饿描述符，而不是过度努力。这些观察结果支持这样一种信念，即空气饥饿是由于呼吸中枢刺激增加加上无法增加 [公式：见正文]e。