Dyspnea is a debilitating and threatening symptom in various diseases. Affected patients often report the unpredictability of dyspnea episodes being particularly anxiety-provoking and amplifying the perception of dyspnea. Experimental studies testing dyspnea unpredictability together with related neural processes, physiological fear responses, and dyspnea-related personality traits are sparse. Therefore, we investigated the impact of unpredictability of dyspnea offset on dyspnea perception and fear ratings, respiratory neural gating and physiological fear indices, as well as the influence of interindividual differences in fear of suffocation (FoS). Forty healthy participants underwent a task manipulating the offset predictability of resistive load-induced dyspnea including one unloaded safety condition. Respiratory variables, self-reports of dyspnea intensity, dyspnea unpleasantness, and fear were recorded. Moreover, respiratory neural gating was measured in a paired inspiratory occlusion paradigm using electroencephalography, while electrodermal activity, startle eyeblink, and startle probe N100 were assessed as physiological fear indices. Participants reported higher dyspnea unpleasantness and fear when dyspnea offset was unpredictable compared to being predictable. Individuals with high levels of FoS showed the greatest increase in fear and overall higher levels of fear and physiological arousal across all conditions. Respiratory neural gating, startle eyeblink, and startle probe N100 showed general reductions during dyspnea conditions but no difference between unpredictable and predictable dyspnea conditions. Together, the current results suggest that the unpredictable offset of dyspnea amplifies dyspnea perception and fear, especially in individuals with high levels of FoS. These effects were unrelated to respiratory neural gating or physiological fear responses, requiring future studies on underlying mechanisms.

中文翻译：

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呼吸困难抵消的不可预测性对呼吸困难感知、恐惧和呼吸神经门控的影响

呼吸困难是各种疾病中使人衰弱和威胁的症状。受影响的患者经常报告呼吸困难发作的不可预测性，尤其会引发焦虑并放大对呼吸困难的感知。测试呼吸困难不可预测性以及相关神经过程、生理恐惧反应和呼吸困难相关人格特征的实验研究很少。因此，我们调查了呼吸困难抵消的不可预测性对呼吸困难感知和恐惧等级、呼吸神经门控和生理恐惧指数的影响，以及对窒息恐惧 (FoS) 的个体差异的影响。40 名健康参与者接受了一项任务，以操纵阻力性负载引起的呼吸困难的偏移可预测性，包括一个空载安全条件。呼吸变量，记录呼吸困难强度、呼吸困难不愉快和恐惧的自我报告。此外，使用脑电图在配对吸气闭塞范式中测量呼吸神经门控，而将皮电活动、惊吓眨眼和惊吓探针 N100 评估为生理恐惧指数。与可预测相比，当呼吸困难补偿不可预测时，参与者报告了更高的呼吸困难不愉快和恐惧。在所有条件下，具有高水平 FoS 的个体表现出最大的恐惧增加和总体更高水平的恐惧和生理唤醒。呼吸神经门控、惊吓眨眼和惊吓探针 N100 在呼吸困难情况下显示普遍减少，但在不可预测和可预测的呼吸困难情况之间没有差异。一起，目前的结果表明，不可预测的呼吸困难抵消会放大呼吸困难的感知和恐惧，尤其是在 FoS 水平较高的个体中。这些影响与呼吸神经门控或生理恐惧反应无关，需要进一步研究潜在机制。