Heart rate and blood pressure responses during hypoxic cycles of a 3-week intermittent hypoxia breathing program in patients at risk for or with mild COPD

Figures & data

Table 1 Baseline characteristics and medication of the study participants of the hypoxia (n=8) and the control group (n=8). Values are means ± standard deviation or numbers (frequencies)

	Hypoxia group	Control group
Age (years)	50±9	55±10
Height (cm)	174±7	172±9
Body mass (kg)	80±16	76±13
Body mass index	26.6±6.3	25.7±3.0
Sex (female/male)	4/4	4/4
FVC (L)	3.46±0.89	3.45±0.72
FEV1 (L)	2.66±0.67	2.46±0.54
Heart rate (bpm)	77±13	78±12
Systolic blood pressure (mmHg)	136±11	146±21
Diastolic blood pressure (mmHg)	88±12	88±11
Arterial oxygen saturation (%)	96.5±0.8	97.1±0.6
Medication, n (%)
Anticholinergics	5 (63)	6 (75)
Corticosteroids	4 (50)	4 (50)
Sympathomimetics	4 (50)	7 (88)
ACE inhibitors	1 (13)	2 (25)
Beta-blockers	1 (13)	0
Calcium antagonists	1 (13)	0
Diuretics	1 (13)	1 (13)

Abbreviations: FVC, forced vital capacity; FEV₁, forced expiratory volume in 1 second.

Table 2 Characteristics of the 3-week breathing program and inspiratory fractions of oxygen (FiO₂) during the breathing cycles of the hypoxia (n=8) and control (n=8) groups

	Week 1					Week 2					Week 3
Session number	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15
Breathing cycles per session	3	3	3	3	3	4	4	4	4	4	5	5	5	5	5
Duration of breathing cycles (minutes)	3	3	3	3	3	4	4	4	4	4	5	5	5	5	5
FiO2 hypoxia group (%)	15	15	15	15	15	13	13	13	13	13	12	12	12	12	12
FiO2 control group (%)	21	21	21	21	21	21	21	21	21	21	21	21	21	21	21

Figure 1 Changes in arterial oxygen saturation from normoxia to acute hypoxia (hypoxia group; black line, n=8), or sham hypoxia (control group; gray line; n=8) during the 15 breathing sessions.

Notes: Data are averages of the 3 to 5 hypoxic/sham hypoxic periods within each breathing session. Values are means ± standard deviation.
Abbreviation: FiO₂, inspired fraction of oxygen.

Figure 2 Changes in blood pressure, heart rate and rate pressure product from normoxia to acute hypoxia (hypoxia group; n=8) or sham hypoxia (control group; n=8) during the 15 breathing sessions.

Notes: Data are averages of the 3 to 5 hypoxic/sham hypoxic periods within each breathing session. Values are means ± standard deviation.

Figure 3 Changes in blood pressure, heart rate and rate pressure product from normoxia to acute hypoxia (hypoxia group; n=8) or sham hypoxia (control group; n=8) during the 3 weeks of the breathing program.

Notes: Data are averages of the five breathing sessions of each week (week 1 to week 3). Values are means ± standard deviation. There was a significant interaction (group and week) for changes in heart rate (two-way ANOVA for repeated measures, P=0.03). *denotes a significant (P<0.05) between-group difference for this week.