From the authors:

From the authors:

We thank J.G. Widdicombe and W.R. Addington for their interest in our work on cough impairment in acute hemispheric stroke patients. In our paper, we proposed that the high reflex cough pressures but impaired cough flow rates demonstrated by the stroke patients could be due to poor coordination between the upper airway, chest and abdominal muscle groups 1. However, we acknowledge that the reflex cough flows could also be reduced by laryngeal constriction secondary to tartaric acid aerosol inhalation. The ideal way to test this hypothesis would be to image the larynx during the tests, but we have not yet developed a method for doing this.

J.G. Widdicombe and W.R Addington were also interested to know whether some patients had lost voluntary cough but maintained reflex cough, or vice versa. These data are given in figure 1. Of 18 stroke patients tested, two could produce neither voluntary cough nor reflex cough in response to 20% tartaric acid. One patient was able to produce voluntary cough but had no reflex cough response. One more patient with no reflex cough response was able to produce voluntary cough. Although, in general, there is a good relationship between reflex cough peak flow and voluntary cough peak flow, there are few individuals (highlighted in circle, both patients and controls) in whom reflex cough flow is lower than voluntary cough flow, but, contrary to Widdicombe and Addington's proposal, there was none in whom reflex cough flow rate was greater than voluntary cough.

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Figure 1–

Reflex versus voluntary cough flow rate. ▾: stroke patients; •: control subjects; ---: individuals with lower reflex than voluntary cough flow rate; —: reference line, y = x.

• ©ERS 2011