Presence of hyperventilation in patients with asthma-like symptoms but negative asthma test responses: provocation with voluntary hyperventilation and mental stress.
BACKGROUND
A group of patients reporting asthma-like symptoms but with negative asthma tests has been identified.


OBJECTIVE
The objective of this study was to determine whether hyperventilation might explain these symptoms and whether the tests could be used as diagnostic tools.


METHODS
A hyperventilation provocation test (HVPT), a mental stress test, and the Word Color Conflict Test (WCCT) were performed on 10 patients with asthma-like symptoms, 10 patients with asthma, and 10 healthy subjects. End-tidal PCO 2 (PETCO2) was recorded 10 minutes after the HVPT and during the WCCT. Blood pressure, heart rate, and respiratory rate were also studied. The Nijmegen symptom questionnaire was used in the assessment of symptoms.


RESULTS
After the HVPT, the PETCO2 values recovered most slowly in the study group, the difference being significant compared with the healthy group (P <.01). During the WCCT, the study group had the lowest PETCO2 values at the 10- and 15-minute measurements, the difference again being significant compared with the healthy group (P <.05). The study group more often experienced symptoms before the test than the group with asthma (P <.05) and the healthy group (P <.001). The study group recognized significantly more symptoms previously experienced during the HVPT than the group with asthma (P <.05) and the healthy group (P <.01) and during the WCCT than the healthy group (P <.05). The study group showed a negative correlation between the PETCO2 level and the number of symptoms after the HVPT at 8 (r = -0-72; P <.05) and 10 minutes (r = -0.76; P <.05) and after the WCCT (r = -0.59; P <.05). Blood pressure, heart rate, and respiratory rate showed small differences between the groups.


CONCLUSIONS
Patients with asthma-like symptoms may experience hyperventilation when provoked. Mental stress might be 1 trigger factor. The HVPT and WCCT can be used as diagnostic instruments.
Ringsberg
K C
KC
Department of Health and Environment, Division for Preventive and Social Medicine and Public Health Science, Linköpings Universitet, Linköping, Sweden.
Akerlind
I
I
D000328:Adult; D001249:Asthma / Q000150:complications* / Q000503:physiopathology; D001794:Blood Pressure; D006339:Heart Rate; D006801:Humans; D006985:Hyperventilation / Q000175:diagnosis* / Q000503:physiopathology / Q000523:psychology*; D016857:Hypocapnia / Q000209:etiology / Q000503:physiopathology; D008875:Middle Aged; D015656:Respiratory Mechanics; D013315:Stress, Psychological / Q000150:complications*