Mrs. A. brings her 3-year-old daughter to see you because she has a “wheezy” cough. Is there any value to her use of this word? Are clinicians any better at describing the acoustic characteristics of cough and do their descriptions help in diagnosis?

In general, we human beings are more visual than acoustic and we define our universe visually as opposed to birds who live in an aurally-defined universe. Consequently, we have a poor vocabulary to define sounds. A recent paper entitled, The Description of Cough Sounds by Healthcare Professionals (Smith JA et al. Cough January 2006, www.coughjournal.com/content/2/1/1) explored how well healthcare professionals could identify a cough. Fifty-three professionals (10 respiratory consultants, 12 respiratory residents and the rest nurses, physiotherapists and clinical physiologists) from a tertiary care respiratory referral centre participated in the study. Each participant listened to 9 short recordings of coughs from common respiratory illness and asked to identify each cough using some common terms such as, dry, moist, productive, brassy, barking, hoarse, wheezy and any other terms the subjects chose. They were then asked to make a diagnosis based on the cough. The coughs were objectively analyzed using a spectrogram. The spectrogram was the “gold standard,” which was then compared to the description given by the subject. The results are interesting. The subjects were good at identifying a cough with mucous (76.1%+/-14.8) but not so good with a cough with a wheeze (39.3%+/-15.0). The correct clinical diagnosis based on the subject’s characterization of the cough was not so good (34%+/-29.0).

Define that rasp

Certain coughs can definitely lead one to suspect a clinical diagnosis: for example, the hoarse stridorous cough of croup. Many parents use the descriptor, “wheeze” for describing stridor and in taking a history it’s often useful to imitate the sound of stridor to help clarify the sound heard by the parent. “Stridor” and “wheeze” have quite different diagnostic implications. Another cough that helps in diagnosis is the paroxysmal cough of pertussis. The Chinese refer to pertussis as the 100-day cough and typically a child with pertussis has episodes of paroxysmal cough and is well between the episodes; gradually with time, the number of episodes diminishes but the intensity of the cough can remain for a long time. The “habit cough” or “cough tic” is also quite characteristic and is the sound of non-productive throat clearing. The “honking” or ‘brassy’ psychogenic cough is also quite specific.

The clinical pearl is that the characteristics of a cough described by the parent can lead you to a correct diagnosis. Better still is either having the child cough for you or asking the parent to bring a video or recording of the child coughing. Most families today have digital cameras capable of recording video and we should make more use of this technology in helping with diagnosis — but more of this in another column.