Chest
Clinical InvestigationsEnd-tidal Pco2 Abnormality and Exercise Limitation in Patients With Primary Pulmonary Hypertension
Section snippets
Materials and Methods
We retrospectively investigated the exercise pathophysiology in 52 patients with PPH referred for evaluation and treatment to our Pulmonary Hypertension Referral Clinic, and 9 healthy volunteers of similar distribution in age and gender (3 men and 6 women; mean age, 39.9 ± 4.8 years [mean ± SE]). The diagnosis of PPH was based on clinical findings and the diagnostic criteria described by the National Institutes of Health registry for PPH and the World Health Organization.1 The Human Subjects
Subject Characteristics
Patient and control subject characteristics are shown in Table 1. There were 7 men and 45 women (age, 43.5 ± 1.8 years) enrolled in the patient group and 3 men and 6 women enrolled in the control group. The patient group was further divided into four groups according to the physiologic grade of severity defined by percentage of predicted peak o2.12 The percentage of predicted AT and e/ co2 at AT were progressively more abnormal as physiologic severity increased (Table 1
Discussion
Normal subjects dwelling near sea level have progressively increased Petco2 by approximately 5 mm Hg above resting values at the AT (Fig 2). In contrast, Petco2 decreases rather than increases from rest to AT in PPH, except for the two subjects with mildest disease, in whom Petco2 did not change. This directional change in Petco2 from rest to AT is greater for a greater reduction in percentage of predicted AT (Fig 4).
The reduction in Petco2 seen in PPH may be accounted for by mechanisms that
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Supported in part by a grant from the American Heart Association (0160126Y).