Coughing in Laryngectomized Patients

Abstract

Ablation of the larynx implies withdrawal of afferent information from receptors involved both in the control of expiratory flow and in the genesis of protective airway reflexes including coughing. To investigate the effects of laryngectomy on the sensory and motor component of coughing, maximal voluntary cough (MVC) efforts as well as the reflex cough (RC) responses at threshold (T) and suprathreshold (1.8 x T, ST) levels induced by inhalation of progressively increasing concentrations of ultrasonically nebulized distilled water (fog) were analyzed in 10 laryngectomized patients and 10 control subjects. Cough intensity was indexed in terms of both the peak amplitude of the integrated electromyographic activity of abdominal muscles (IEMGP) and the ratio of IEMGP to the duration of the expiratory ramp (TEC), i.e., the rate of rise of IEMG activity (IEMGP/TEC). Cough peak flow was also recorded. Cough threshold was similar in patients and controls, as were IEMGP, TEC, and IEMGP/ TEC recorded during MVC and RCST. In contrast, during RCT, patients' IEMGP was significantly reduced (p < 0.05), thus leading to a significant decrease in IEMGP/TEC (p < 0.05) even in the absence of significant differences in TEC. Cough flow closely correlated with IEMG-related variables. Cough volume acceleration, i. e., the ratio of cough peak flow to the corresponding time to cough peak flow was also significantly reduced in the patients, especially during RCT (p < 0.01). The results suggest that the lack of signals arising from the larynx may result in a reduction of cough volume acceleration as well as in the intensity of abdominal muscle contractions during RCT. These factors may contribute to facilitate the onset and/or the persistence of chest infections in laryngectomized patients.

What is cough and what should be measured?

“…The inductance vest is probably inaccurate during the vigorous movements of the torso in coughing; however, cough expiratory flow and volume during voluntary or induced cough efforts can be measured fairly accurately using a calibrated pneumotachograph [17]. Since the force developed during the expulsions of cough largely depends upon the magnitude of the preceding inspiration [11], measurements of cough inspiratory volume might also represent a useful indicator of cough intensity.…”

“…Since the magnitude of EMG activity correlates with the force produced by the contracting muscle [31], recordings of EMG activity of human abdominal muscle activity have been used to assess the intensity of induced cough efforts [see 32, and for further refs]. In particular, the 'moving average' integrated EMG activity of the obliquus externus muscle, perhaps the principal muscle implicated in the production of cough force, has been used to evaluate the intensity of voluntary and reflex cough efforts in humans [11,17].…”

“…Measurement of inspiratory and, especially, expiratory airflows can characterize cough and are fairly easy to apply [8,17]. Their limitation is that they are secondary indices of the intensity of cough and their values will depend on such factors as the degree of closure of the larynx as well as the force of contraction of the expiratory muscles.…”

Capsaicin exposure elicits complex airway defensive motor patterns in normal humans in a concentration-dependent manner

“…Lasserson et al [10] showed a much higher activation of 79.7±41.6% following tartaric acid inhalation. Normalizing peak EMG activity for EO produced a 50% increase in cats with mechanical stimulation of the larynx [23] and 78-83% in humans using fog [5,17,19]. In addition to method of analysis, the type of tussive agent used and the species of the test subject will also add variability to the data.…”

“…With this technique, capsaicin concentrations (or other tussives such as citric acid and distilled water) are doubled until two and five "cough events" (typically defined by the number of expulsive events, or "cough sounds") are achieved, representing the threshold and suprathreshold response, respectively. These studies have shown differences in the cough response between ages [13], genders [14][15][16] and diseases [4,5,13,17]. However, these data cannot infer changes in expiratory muscle activation, duration of expulsive phases and the airflow dynamics with increasing capsaicin concentration, all which are essential components in defining the cough response.…”