HYPERVENTILATION IN PATIENTS WITH RECURRENT FUNCTIONAL SYMPTOMS

In view of the similarity between the reported effects of hyperventila tion and recurrent functional symptom presented in primary care, a stu dy was undertaken to establish whether such symptoms are attributable to hyperventilation. Twenty patients with two or more recurrent functi onal symptoms which their doctors found difficult to diagnose or treat , and 30 controls, were studied using symptom questionnaires and a ser ies of hyperventilation provocation tests during which the partial pre ssure of carbon dioxide (PCO2) and symptoms were recorded. Sixteen cas es (80%) had unexplained breathlessness compared with two of the contr ols (7%). All of the cases recognized familiar functional symptoms dur ing provoked hyperventilation, and in 16 (80%), these included primary physical symptoms; only 23% of the controls recognized any previously experienced symptom. Considerable overlap of PCO2 values between grou ps meant that absolute values of PCO2 were not useful in differentiati ng between groups, but cases were more likely than controls to have a PCO2 of less than 4 kPa at rest, three minutes after hyperventilation, or during mental stress (75% of cases fulfilled one or more of these criteria versus 40% of controls). This is the first study in primary c are to examine the effect of hyperventilation in a group of patients w ith multiple somatic symptoms. The findings have implications for the recognition and management of such patients.