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Does the hypoxic ventilatory response predict the oxygen-induced falls in ventilation in COPD?
R B Berry1, C K Mahutte, J L Kirsch
1Veterans Medical Center, Long Beach, Calif. 90822.
Chest
|March 1, 1993
Summary
Supplemental oxygen decreases ventilation and mouth occlusion pressure in COPD patients. These changes are not linked to individual hypoxic ventilatory responses, suggesting complex regulation in chronic obstructive pulmonary disease.
Area of Science:
- Respiratory Medicine
- Pulmonary Physiology
Background:
- Patients with Chronic Obstructive Pulmonary Disease (COPD) often experience decreased ventilation (VE) and mouth occlusion pressure (P0.1) when given supplemental oxygen.
- The relationship between these decreases and the patients' individual responses to hypoxia is not fully understood.
Purpose of the Study:
- To investigate if supplemental oxygen-induced reductions in VE and P0.1 in COPD patients correlate with their ventilatory and P0.1 responses to hypoxia.
- To analyze the relationship between changes in oxygen saturation (SaO2) and the corresponding changes in VE and P0.1.
Main Methods:
- 14 COPD patients with a mean FEV1 of 0.95 L participated.
- Measurements of VE and P0.1 were taken while patients breathed room air or supplemental oxygen (1-2 L/min) in a randomized, single-blind manner.
- Hypoxic ventilatory and P0.1 responses were assessed using delta VE/delta SaO2 and delta P0.1/delta SaO2.
Main Results:
- Supplemental oxygen increased SaO2 from 90.8% to 95.2% and decreased VE (12.3 to 11.6 L/min, p < 0.03) and P0.1 (2.50 to 2.26 cm H2O, p < 0.05).
- Individual changes in VE and P0.1 during oxygen breathing did not significantly correlate with changes in SaO2 or with the calculated hypoxic ventilatory/P0.1 responses (delta VE/delta SaO2, delta P0.1/delta SaO2).
Conclusions:
- Supplemental oxygen causes a significant decrease in ventilation and mouth occlusion pressure in COPD patients.
- This reduction is not directly related to the patients' baseline hypoxic ventilatory or P0.1 responsiveness, indicating other regulatory mechanisms may be involved.