Effect of Nocturnal Oxygen on Blood Pressure Response to Altitude Exposure in COPD – Data from a Randomized Placebo-Controlled Cross-Over Trial

Figures & data

Table 1 Patient Characteristics in the per Protocol Population

Variable	N = 23
Men, No (%)	11 (48)
Women, No (%)	12 (52)
Age, years	66.0 (5.3)
Body Mass Index, kg/m^2	25.1 (3.7)
FEV1, liters	1.7 (0.5)
FEV1, % predicted	62 (14)
FVC, liters	3.2 (0.7)
FVC, % predicted	90 (12)
FEV1/FVC, absolute value	0.5 (0.1)
TLCO (Hb), mmol/min/kPa	5.7 (2.0)
TLCO (Hb), % predicted	70 (20)
GOLD grade 2, No (%)	18 (78)
Comorbidities
Cardiovascular disease (hypertension or coronary heart disease), No. (%)	14 (60)
Diabetes, No (%)	3 (13)
Depression, No (%)	3 (13)
Medication
Inhaled glucocorticoids, No (%)	9 (39)
Inhaled β-adrenergics, No (%)	16 (70)
Inhaled anticholinergics, No (%)	16 (70)
Diuretics, No (%)	4 (17)
Antihypertensive medication, No (%)	11 (48)
-Beta-blocker, No (%)	1 (4)
-ACE-I or ARB, No (%)	9 (39)
-Calcium channel blocker, No (%)	6 (26)
-Diuretics and other antihypertensive medications, No (%)	5 (22)
Antidiabetics, No (%)	3 (13)
Antidepressants, No (%)	5 (22)

Notes: Continuous variables are presented as mean (SD) and categorical variables are presented as numbers (%).

Abbreviations: ACEI, angiotensin-converting enzyme inhibitors; ARB, angiotensin receptor blockers; FEV₁, forced expiratory volume in the first second of expiration; FVC, forced vital capacity; TLco, transfer factor of the lung for carbon monoxide; GOLD, Global Obstructive Lung Disease classification.

Figure 1 Simplified patient flow chart. See²⁶ for four arm allocation of the intention-to-treat-analysis in the main trial. Severe hypoxemia was defined as an arterial oxygenation measured by finger oximetry <75% for >30 min.

Table 2 Effect of Altitude and Treatment Effect of NOT

	490 m	2048 m Placebo	2048 m NOT	490–2048 m Placebo		490–2048 m NOT		Treatment Effect, Δ2048 m NOT – Δ2048 placebo		Overall p (ANOVA)
				Δ (95%C)	p	Δ (95%C)	p	Δ (95%C)	p
Systolic BP (n=23)	121.0 (32.8)	137.7 (21.4)	122.7 (25.4)	8.5 (−0.7 to 19.0)	0.03	2.5 (−8.5 to 7.8)	0.88	−5.8 (−22.3 to −1.4)	0.05	0.05
Diastolic BP (n=23)	62.2 (13.0)	69.0 (12.9)	64.0 (8.8)	5.5 (0.3 to 12.3)	<0.01	3.2 (0.03 to 7.3)	0.09	−3.5 (−12.6 to 23.0)	0.21	0.01
BRS (msec/mmHg) (n=12)	4.8 (2.8)	2.5 (2.0)	4.9 (3.5)	−0.9 (−3.2 to 0.0)	0.07	0.4 (−1.2 to 1.9)	0.54	1.7 (0.3 to 3.4)	0.02	0.03
Heart rate (n=23)	68.6 (10.4)	73.7 (11.6)	69.3 (14.1)	6.5 (2.8 to 8.6)	<0.01	0.4 (−1.2 to 3.7)	0.64	−5.7 (−7.9 to −2.9)	<0.01	<0.01
CV systolic BP (%) (n=23)	5.5 (2.0)	5.7 (1.4)	5.5 (2.0)	−0.05 (−0.8 to 0.9)	0.75	0.1 (−0.8 to 1.1)	0.88	−0.4 (−1.4 to 1.3)	0.88	0.95
CV diastolic BP (%) (n=23)	5.2 (2.0)	5.8 (1.5)	5.0 (2.3)	0.8 (−0.8 to 1.5)	0.64	−0.3 (−1.3 to 2.2)	0.64	−0.5 (−1.6 to 0.5)	0.35	0.64

Notes: Data are presented as median (IQR). P-values are presented as results of Friedman test.

Abbreviations: BP, blood pressure; BRS, baroreflex sensitivity; CV, coefficient of variation; NOT, nocturnal oxygen supplementation.

Figure 2 Systolic (A) and diastolic (B) blood pressure (BP), baroreflex sensitivity (BRS; (C) and heart rate (HR; (D) compared between the three assessments (median and IQR) – room air at low altitude (490 m), placebo (room air) at altitude (2048 m) and nocturnal oxygen therapy (NOT) at altitude (2048 m).

Tan L, Latshang TD, Aeschbacher SS, et al. Effect of nocturnal oxygen therapy on nocturnal hypoxemia and sleep apnea among patients with Chronic Obstructive Pulmonary Disease traveling to 2048 meters: a randomized clinical trial. JAMA Netw Open. 2020;3(6):e207940. doi:10.1001/jamanetworkopen.2020.7940

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