Young S, Abdul-Sattar N, Caric D
Department of Physiology, University Medical School, Edinburgh, UK.
Bull Eur Physiopathol Respir. 1987;23 Suppl 10:11s-17s.
For about 150 years, there has been emphasis on the importance of glottic closure and high flows in coughing. During voluntary coughing in normal subjects, the main expiratory flow usually begins as thoracic and abdominal pressures are rising. However, sometimes it starts at peak pressure whereas at other times flow and pressure rise together. Plateau flow in single coughs remains relatively constant in the face of large changes in pressure. In a group of coughs following a single inspiration, the fall in pressure is less during plateau flow. Consequently, for the same oral flows, it is likely that the mean linear velocity in the intrathoracic airways will be greater than in a single cough. Recordings have also been made of early morning involuntary coughing in patients with obstructive airways disease. Flow, volume and sound were recorded and sputum expectoration was noted. Sputum expectoration usually occurs after groups of coughs following single inspirations. Hence the movement of the equal pressure point peripherally may be important. These patients have very low flows and yet their coughs are productive. Sound often occurs during the whole of the low flow period immediately before the main expulsive phase. This could only occur if the glottis was open. Thus productive cough can occur without glottic closure and with low airflows.
在大约150年的时间里，人们一直强调声门关闭和咳嗽时高气流的重要性。在正常受试者的自主咳嗽过程中，主要呼气气流通常在胸内压和腹内压升高时开始。然而，有时它在压力峰值时开始，而在其他时候气流和压力同时升高。单次咳嗽中的平台期气流在压力大幅变化时保持相对恒定。在单次吸气后的一组咳嗽中，平台期气流期间压力下降较少。因此，对于相同的口腔气流，胸内气道中的平均线性速度可能比单次咳嗽时更大。对患有阻塞性气道疾病的患者清晨非自主咳嗽也进行了记录。记录了气流、容积和声音，并记录了痰液咳出情况。痰液咳出通常发生在单次吸气后的一组咳嗽之后。因此，等压点向周边移动可能很重要。这些患者气流非常低，但他们的咳嗽却能咳出痰液。在主要呼气阶段之前的整个低气流期通常都会出现声音。这只有在声门打开时才会发生。因此，无声音门关闭且气流低时也能发生有效咳嗽。
