Key result
Nocturnal oxygen therapy significantly mitigated the altitude-induced increase in systolic blood pressure compared to placebo (median difference -5.8 mmHg) in patients with COPD.
Why the study?
Altitude exposure increases blood pressure and decreases baroreflex sensitivity in COPD, but whether nocturnal oxygen therapy mitigates these cardiovascular autonomic changes is unknown.
Does nocturnal oxygen therapy mitigate altitude-induced increases in blood pressure and decreases in baroreflex sensitivity in patients with moderate-to-severe COPD?
RCT (n=32)
Single-blind
Randomized cross-over
No
Does nocturnal oxygen therapy mitigate altitude-induced increases in blood pressure and decreases in baroreflex sensitivity in patients with moderate-to-severe COPD?
Mean Difference: -5.8 (95% CI -22.2–-1.4)
Absolute Event Rate: 2.5% vs 8.5%
p-value: p=0.05
Nocturnal oxygen may blunt altitude-related BP rises in COPD patients; extends RCT evidence on oxygen beyond hypoxemia correction.
Purpose: Patients with chronic obstructive pulmonary disease (COPD) are particularly vulnerable to hypoxia-induced autonomic dysregulation. Hypoxemia is marked during sleep. In COPD, altitude exposure is associated with an increase in blood pressure (BP) and a decrease in baroreflex-sensitivity (BRS). Whether nocturnal oxygen therapy (NOT) may mitigate these cardiovascular autonomic changes in COPD at altitude is unknown. Materials and methods: In a randomized placebo-controlled cross-over trial, 32 patients with moderate-to-severe COPD living <800 m were subsequently allocated to NOT and placebo during acute exposure to altitude. Measurements were done at low altitude at 490 m and during two stays at 2048 m on NOT (3 L/min) and placebo (3 L/min, ambient air) via nasal cannula. Allocation and intervention sequences were randomized. Outcomes of interest were BP, BRS (from beat-to-beat BP measurement), BP variability (BPV), and heart rate. Results: About 23/32 patients finished the trial per protocol (mean (SD) age 66 (5) y, FEV1 62 (14) % predicted) and 9/32 experienced altitude-related illnesses (8 vs 1, p < 0.05 placebo vs NOT). NOT significantly mitigated the altitude-induced increase in systolic BP compared to placebo (Δ median -5.8 [95% CI -22.2 to -1.4] mmHg, p = 0.05) but not diastolic BP (-3.5 [95% CI -12.6 to 3.0] mmHg; p = 0.21) or BPV. BRS at altitude was significantly higher in NOT than in placebo (1.7 [95% CI 0.3 to 3.4] ms/mmHg, p = 0.02). Conclusion: NOT may protect from hypoxia-induced autonomic dysregulation upon altitude exposure in COPD and thus protect from a relevant increase in BP and decrease in BRS. NOT may provide cardiovascular benefits in COPD during conditions of increased hypoxemia and may be considered in COPD travelling to altitude.
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Mészáros et al. (2021) conducted an RCT in Chronic Obstructive Pulmonary Disease (COPD) (n=32). Nocturnal oxygen therapy vs. Placebo (3 L/min room air) was evaluated on Difference in altitude-induced change in morning systolic blood pressure (Median difference -5.8 mmHg, 95% CI -22.2 to -1.4, p=0.05). Nocturnal oxygen therapy significantly mitigated the altitude-induced increase in systolic blood pressure compared to placebo (median difference -5.8 mmHg) in patients with COPD.
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