Spence D P, Graham D R, Jamieson G, Cheetham B M, Calverley P M, Earis J E
Aintree Chest Centre, Fazakerley Hospital, Liverpool, United Kingdom.
Am J Respir Crit Care Med. 1996 Aug;154(2 Pt 1):290-4. doi: 10.1164/ajrccm.154.2.8756796.
Wheeze is a classic sign of airflow obstruction but relatively little is known of its mechanism of production or its relationship to the development of airflow obstruction. We studied eight asthmatic subjects age (mean +/- 5D) 42 +/- 5 yr, FEV1 2.46 +/- 0.36 L during an extended, symptom-limited methacholine challenge test. Breath sounds were detected by a microphone over the right upper anterior chest. Spectral analysis was by a fast Fourier transform algorithm. Mean FEV1 fell by 51 +/- 14% to 1.28 +/- 0.61 L during the challenge and airways resistance increased by 119 +/- 50%. There were no consistent changes in breathing pattern or tidal volume during the challenge. Wheeze occurred late in the challenge at the highest concentration of methacholine administered and only after expiratory tidal flow limitation had been reached. Five subjects developed wheeze on tidal breathing, the remaining three only wheezed on deep breathing. Wheezing sounds were reproducible between breaths, coefficient of variation of starting sound frequency was 4.2% and ending frequency 12%. Mean frequency of expiratory wheezes was 669 +/- 100 Hz and inspiratory wheezes 710 +/- 76 Hz. Expiratory wheeze fell in pitch during a breath (mean fall in sound frequency 187 +/- 43 Hz) but inspiratory wheezes were more variable. Expiratory wheezes occurred late in the respiratory cycle at a mean of 58% of the maximal tidal expiratory flow, whereas inspiratory wheezes occurred around maximal tidal inspiratory flows, suggesting that the mechanisms of production of inspiratory and expiratory wheezes may be different. In this model, the presence of wheeze during tidal breathing was a sign of severe airflow limitation.
哮鸣是气流阻塞的典型体征，但对其产生机制或与气流阻塞发展的关系却知之甚少。我们研究了8名年龄（平均±5标准差）为42±5岁的哮喘患者，在延长的、症状限制的乙酰甲胆碱激发试验期间，其第一秒用力呼气容积（FEV1）为2.46±0.36L。通过置于右上前胸的麦克风检测呼吸音。采用快速傅里叶变换算法进行频谱分析。激发试验期间，平均FEV1下降了51±14%，降至1.28±0.61L，气道阻力增加了119±50%。激发试验期间呼吸模式或潮气量没有一致的变化。哮鸣在给予最高浓度乙酰甲胆碱的激发试验后期出现，且仅在达到呼气潮气流速受限后出现。5名受试者在平静呼吸时出现哮鸣，其余3名仅在深呼吸时哮鸣。哮鸣音在呼吸之间具有可重复性，起始声音频率的变异系数为4.2%，结束频率为12%。呼气哮鸣音的平均频率为669±100Hz，吸气哮鸣音为710±76Hz。呼气哮鸣音在一次呼吸过程中音调下降（声音频率平均下降187±43Hz），但吸气哮鸣音变化更大。呼气哮鸣音在呼吸周期后期出现，平均出现在最大呼气潮气流速的58%时，而吸气哮鸣音出现在最大吸气潮气流速附近，这表明吸气和呼气哮鸣音的产生机制可能不同。在这个模型中，平静呼吸时出现哮鸣是严重气流受限的标志。
