Cough Frequency in Patients with Respiratory Disease1, 2

Cough is an important manifestation of respiratory disease, but it is not easy to quantitate. Normally it is determined whether a patient has a cough by asking him; however, his answers are a measure of his awareness of cough rather than of his cough frequency. A patient's awareness of cough is certainly related to cough frequency, but it is also affected by other things, such as whether his cough makes him dyspneic, or hurts him, or whether it is a recent development. Several workers have developed equipment to measure cough frequency objectively. Gravenstein and associates ( 1) first reported actual cough counts recorded from patients. They used an instrument that produced a graphic strip-chart recording, but found it difficult to differentiate between coughs and other sounds. Woolf and Rosenberg (2) and Sivelius and Colmore (3) used tape recorders triggered by sound to measure cough frequency in the assessment of antitussive drugs. Recordings were read-out by ear. Equipment has been used at Woodlawn Hospital for the last four years to count coughs in patients suffering from a variety of respiratory disorders.