Department of Psychology, Southern Methodist University, PO Box 750442, Dallas, TX 75275-0442, USA.
Psychosom Med. 2013 Feb;75(2):187-95. doi: 10.1097/PSY.0b013e31827d1072. Epub 2013 Jan 16.
Anxiety and panic are associated with the experience of a range of bodily symptoms, in particular unpleasant breathing sensations (dyspnea). Respiratory theories of panic disorder have focused on disturbances in blood gas regulation, but respiratory muscle tension as a source of dyspnea has not been considered. We therefore examined the potential of intercostal muscle tension to elicit dyspnea in individuals with high anxiety sensitivity, a risk factor for developing panic disorder.
Individuals high and low in anxiety sensitivity (total N=62) completed four tasks: electromyogram biofeedback for tensing intercostal muscle, electromyogram biofeedback for tensing leg muscles, paced breathing at three different speeds, and a fine motor task. Global dyspnea, individual respiratory sensations, nonrespiratory sensations, and discomfort were assessed after each task, whereas respiratory pattern (respiratory inductance plethysmography) and end-tidal carbon dioxide (capnography) were measured continuously.
In individuals with high compared to low anxiety sensitivity, intercostal muscle tension elicited a particularly strong report of obstruction (M=5.1, SD=3.6 versus M=2.5, SD=3.0), air hunger (M=1.9, SD=2.1 versus M=0.4, SD=0.8), hyperventilation symptoms (M=0.6, SD=0.6 versus M=0.1, SD=0.1), and discomfort (M=5.1, SD=3.2 versus M=2.2, SD=2.1) (all p values<.05). This effect was not explained by site-unspecific muscle tension, voluntary manipulation of respiration, or sustained task-related attention. Nonrespiratory control sensations were not significantly affected by tasks (F<1), and respiratory variables did not reflect any specific responding of high-Anxiety Sensitivity Index participants to intercostal muscle tension.
Respiratory muscle tension may contribute to the respiratory sensations experienced by panic-prone individuals. Theories and treatments for panic disorder should consider this potential source of symptoms.
焦虑和恐慌与一系列身体症状有关，特别是不愉快的呼吸感觉（呼吸困难）。恐慌障碍的呼吸理论集中在血气调节紊乱上，但尚未考虑呼吸肌紧张作为呼吸困难的来源。因此，我们研究了肋间肌紧张在高焦虑敏感个体中引起呼吸困难的潜力，高焦虑敏感是发展为恐慌障碍的风险因素。
高焦虑敏感（总 N=62）和低焦虑敏感个体完成了四项任务：肋间肌紧张肌电生物反馈、腿部肌肉紧张肌电生物反馈、三种不同速度的呼吸节奏、精细运动任务。在完成每个任务后，评估整体呼吸困难、个体呼吸感觉、非呼吸感觉和不适，同时连续测量呼吸模式（呼吸感应体积描记法）和呼气末二氧化碳（呼气末二氧化碳描记法）。
与低焦虑敏感个体相比，高焦虑敏感个体的肋间肌紧张会引起特别强烈的阻塞感（M=5.1，SD=3.6 与 M=2.5，SD=3.0）、空气饥饿感（M=1.9，SD=2.1 与 M=0.4，SD=0.8）、过度通气症状（M=0.6，SD=0.6 与 M=0.1，SD=0.1）和不适（M=5.1，SD=3.2 与 M=2.2，SD=2.1）（所有 p 值均<.05）。这种效应不能用非特定部位肌肉紧张、自愿控制呼吸或持续的任务相关注意力来解释。非呼吸控制感觉不受任务影响（F<1），呼吸变量也不能反映高焦虑敏感指数参与者对肋间肌紧张的特定反应。
呼吸肌紧张可能导致易惊恐个体的呼吸感觉。恐慌障碍的理论和治疗方法应考虑这种潜在的症状来源。
