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Biomedical subjects

Alexandre M Valença

Publications and source records attributed to Alexandre M Valença.

24 records · Page 2Linked to original sources
PubMed2002

Panic disorder and obsessive compulsive disorder in a hyperventilation challenge test.

BACKGROUND: Stress-induced hyperventilation produces symptoms that people are prone to misinterpret as life-threatening if they are unaware of the consequences of overbreathing. Our aim was to observe the induction of panic attacks by a hyperventilation challenge test in a series of panic disorder and obsessive compulsive disorder (OCD) patients (DSM-IV). METHOD: We randomly selected 28 panic disorder patients, 21 OCD patients and 28 normal volunteers. All patients were drug free for a week. They were induced to hyperventilate (30 breaths/min) for 4 min. Anxiety scales were applied before and after the test. RESULTS: A total of 64.3% (n=18) panic disorder patients, 9.5% (n=2) OCD patients and 3.6% (n=1) of control subjects had a panic attack after hyperventilating (chi(2)=3.99, d.f.=2, P=0.026). LIMITATIONS: The hyperventilation challenge test has a low sensitivity for panic disorder. CONCLUSION: In this challenge test the panic disorder patients were more sensitive to hyperventilation than OCD patients and normal volunteers. The induction of panic attacks by voluntary hyperventilation may be an easy test for validating the diagnosis in certain panic disorder patients.

Adult↗
PubMed2002

Carbon dioxide test as an additional clinical measure of treatment response in panic disorder.

OBJECTIVE: We aim to determine if a treatment with a dose of clonazepam--2 mg/day, for 6 weeks, blocks spontaneous panic attacks and the ones induced by the inhalation of 35% carbon dioxide (CO2) in panic disorder (PD) patients. The CO2 challenge-test may be a useful addition tool for measuring the pharmacological response during the initial phase (6 weeks) in the treatment of PD. METHOD: Eighteen PD patients drug free for a week participated in a carbon dioxide challenge test. Fourteen had a panic attack and were openly treated for a 6-week period with clonazepam. At the end of the 6-week period they were submitted again to the CO2 challenge test. RESULTS: After 6 weeks of treatment with clonazepam, 12 of 14 PD patients (85.7%) did not have a panic attack after the CO2 challenge test. Just 2 of 14 patients (14.3%) had a panic attack after the CO2 challenge test. Ten of 14 (71.4%) PD patients had panic free status after clonazepam treatment. The 2 patients who had a panic attack in the sixth week, after the CO2 test, did not have panic free status after the treatment with clonazepam. CONCLUSION: The CO2-test may be a valid tool for testing and predicting the drug response.

Administration, Inhalation↗
PubMedDate not supplied

Psychopathological profile of 35% CO2 challenge test-induced panic attacks: a comparison with spontaneous panic attacks.

Our aim was to describe the clinical features of 35% CO2-induced panic attacks in patients with panic disorder (PD) (Diagnostic and Statistical Manual and Mental Disorders, Fourth Edition) and compare them with the last spontaneous panic attack in patients with PD who had not had a panic attack after the 35% CO2 challenge test. We examined 91 patients with PD submitted to the CO2 challenge test. The test consisted of exhaling as fully as possible, took a fast vital capacity breath, held their breath for 8 seconds, exhaled, and then repeated the fast vital capacity breath, again holding for 8 seconds. The patients inhaled the 35% CO2/65% O2 mixture or atmospheric compressed air, randomly selected in a double-blind design. Scales were applied before and after the test. A total of 68.1% (n = 62) patients with PD had a panic attack (responders) after the CO2 test (chi2(1) = 25.87, P = .031). The last spontaneous panic attack and the symptom profile from the patients with PD who had not had a panic attack after the test (n = 29, 31.9%) were described to compare. The responders had more respiratory symptoms (chi2(1) = 19.21, P < .001), fulfilling the criteria for respiratory PD subtype (80.6%); the disorder started earlier (Mann-Whitney, P < .001), had a higher familial prevalence of PD (chi2(1) = 20.45, P = .028), and had more previous depressive episodes (chi2(1) = 27.98, P < .001). Our data suggest that there is an association between respiratory PD subtype and hyperreactivity to a CO2 respiratory challenge test. The responders may be a subgroup of respiratory PD subtype with future diagnostic and therapeutic implications.

Adult↗