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隨意持續高通氣下通氣肌疲勞的呼吸模式

Breathing Pattern of Ventilatory Muscle Fatigue during Voluntary Sustained Hyperpnea

摘要


One of the autonomic mediated respiratory changes during ventilatory muscles fatigue is a rapid and shallow breathing pattern. The changes of breathing pattern during exhaustive voluntary sustained hyperpneic mancuver is not known. The purpose of this study was to examine such kind of changes. Subjects were 14(8 males and 6 females) volunteer university students. Measurements included pulmonary functions, maximum oxygen uptake (using Douglas bag technique), and sustained hyperpnea endurance at 66% of individual's maximum voluntary ventilation. Subjects were required to increase respiratory effort to maintain the spirometer volume below a defined level. The spirometer was continuously supplied with humidified air at a rate of the target flow.End-tidalCO2 level was maintained within normal range. Ventilation was measured on-line from the expired side using pneumotachograph technique and a custommade computer-assisted system providing an immediate feedback. Sustained hyperpnea time was 55.6±40.0(Mean ± SD). Nine subjects(5 males and 4 females)had higher final respiratory frequency(46.0±7.8 vs.55.5±6.1 cycle. min^(-1), p<.001), lower final tidal volume(2.21±.41vs. 1.80±.27L, p<.001), and lower final tidal volume/forced vital capacity ratio(56±7vs. 46±5%, p<.001), The other 5 subjects showed an opposite breathing pattern, respectively, 58.0±6.2 vs. 52.6±7.3 cycle. min^(-1), p<.01; 1.74±.41 vs.1.92±.51L, p<.05; and 45±4 vs.49±3%, p<.05. The difference in breathing pattern between the two groups occurred only in the beginning of hyperpnea, while no difference (p>.05) was found in all other measurements. It was speculated that differ in initial breathing pattern was associated with increased anxiety induced by chasing a moving target. In conclusion, an adaptative response of ventilatory muscle to exhaustive sustained hyperpnea exercise was a faster and less deep breathing pattern.

並列摘要


One of the autonomic mediated respiratory changes during ventilatory muscles fatigue is a rapid and shallow breathing pattern. The changes of breathing pattern during exhaustive voluntary sustained hyperpneic mancuver is not known. The purpose of this study was to examine such kind of changes. Subjects were 14(8 males and 6 females) volunteer university students. Measurements included pulmonary functions, maximum oxygen uptake (using Douglas bag technique), and sustained hyperpnea endurance at 66% of individual's maximum voluntary ventilation. Subjects were required to increase respiratory effort to maintain the spirometer volume below a defined level. The spirometer was continuously supplied with humidified air at a rate of the target flow.End-tidalCO2 level was maintained within normal range. Ventilation was measured on-line from the expired side using pneumotachograph technique and a custommade computer-assisted system providing an immediate feedback. Sustained hyperpnea time was 55.6±40.0(Mean ± SD). Nine subjects(5 males and 4 females)had higher final respiratory frequency(46.0±7.8 vs.55.5±6.1 cycle. min^(-1), p<.001), lower final tidal volume(2.21±.41vs. 1.80±.27L, p<.001), and lower final tidal volume/forced vital capacity ratio(56±7vs. 46±5%, p<.001), The other 5 subjects showed an opposite breathing pattern, respectively, 58.0±6.2 vs. 52.6±7.3 cycle. min^(-1), p<.01; 1.74±.41 vs.1.92±.51L, p<.05; and 45±4 vs.49±3%, p<.05. The difference in breathing pattern between the two groups occurred only in the beginning of hyperpnea, while no difference (p>.05) was found in all other measurements. It was speculated that differ in initial breathing pattern was associated with increased anxiety induced by chasing a moving target. In conclusion, an adaptative response of ventilatory muscle to exhaustive sustained hyperpnea exercise was a faster and less deep breathing pattern.

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