Chest
Clinical InvestigationsMechanisms of Oxygen Effects on Exercise in Patients with Chronic Obstructive Pulmonary Disease
Section snippets
Materials and Methods
We studied a group of nine patients with COPD who volunteered and gave informed consent. There were eight men and one woman. The characteristics of the patients are shown in Table 1. All had severe obstructive pulmonary disease with a forced expiratory volume in one second (FEV1) less than 48 percent of the predicted value. All had severely impaired functional capacity (class 4, American Medical Association's classification of respiratory impairment8); ie, they experienced shortness of breath
Results
All of the patients except one demonstrated an increase in the duration of exercise tolerated when breathing the 30 percent oxygen mixture (Fig 1). The maximum ventilation achieved at the breaking point of exercise was strikingly similar for each patient whether breathing air or supplemental oxygen, and no significant difference in this measurement was found between the two exercise runs. Considering the group as a whole, total work (as measured by total consumption of oxygen) increased an
Discussion
Our findings confirm previous reports which describe the improved exercise tolerance in persons with severe COPD during breathing of supplemental oxygen. This was achieved mainly by maintaining the uptake of oxygen from the enriched alveolar gas at a lower total ventilation. The reduction in ventilation seemed to be related to hypoxic drive, because ventilation correlated well with SaO2. This is consistent with the observation in normal subjects that the magnitude of ventilation per unit of
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Oxygen Therapy and Noninvasive Ventilation in Chronic Obstructive Pulmonary Disease
2020, Clinics in Chest MedicineCitation Excerpt :Arterial lactate levels are elevated in hypoxemic patients with COPD,4 which reflects a greater reliance on anaerobic metabolism1 and is a strong mortality predictor.5 SOT reduces lactate levels,6 which indirectly indicates improved tissue oxygenation. Consequently, SOT leads to improvements of multiple physiologic functions (Table 1).6–16
Would a right shift of the oxy-hemoglobin dissociation curve improve exercise capacity in patients with heart failure?
2020, Medical HypothesesCitation Excerpt :Taken together, the question is raised whether oxygen delivery to skeletal muscle tissue can be increased independent of alterations in cardiac output and/or muscle blood flow. In the past, oxygen supplementation using non-invasive mechanical ventilation has been utilized [8–10] in certain critical illness to improve oxygen saturation (SaO2) or oxygen availability. However, chronic oxygen supplementation may elicit adverse effects including reductions in cardiac output, stroke volume and an increase in vascular resistance [11–13].
Physiologic Effects of Oxygen Supplementation During Exercise in Chronic Obstructive Pulmonary Disease
2019, Clinics in Chest MedicineCitation Excerpt :Breathing O2 reduces the ventilatory requirement during exercise at the same work intensity, and allows the patient with COPD to exercise longer until maximum ventilation is reached at a higher work rate.23 Stein and colleagues23 observed a linear correlation (r = 0.63) between minute ventilation and arterial O2 saturation in patients with severe COPD. Iso-time ventilation was consistently lower in patients with COPD breathing supplemental O2 at a 0.30 Fio2 compared with patients breathing air, suggesting that the reduction in ventilation is related to reduced hypoxic drive because of elevated O2 saturation that supplemental O2 yields.23
Continuous Home Oxygen Therapy
2014, Archivos de Bronconeumologia