RESUMO
Respiratory abnormalities are associated with anxiety, particularly with panic attacks. Symptoms such as shortness of breath, "empty-head" feeling, dizziness, paresthesias and tachypnea have been described in the psychiatric and respiratory physiology related to panic disorder. Panic disorder patients exhibit both behaviorally and physiologically abnormal responses to respiratory challenges tests. Objective; We aim to observe the induction of panic attacks by hyperventilation in a group of panic disorder patients (DSM-IV). Method: 13 panic disorder patients and 11 normal volunteers were randomly selected. They were drug free for a week. They were induced to hyperventilate (30 breaths/min) for 3 minutes. Anxiety scales were taken before and after the test. Results: 9 (69.2 per cent) panic disorder patients and one (9.1 per cent) of control subjects had a panic attack after hyperventilating (p<0.05). Conclusion: The panic disorder group was more sensitive to hyperventilation than normal volunteers. The induction of panic attacks by voluntary hyperventilation may be a useful and simple test for validating the diagnosis in some specific panic disorder patients.