Walking with Non-Invasive Ventilation Does Not Prevent Exercise-Induced Hypoxaemia in Stable Hypercapnic COPD Patients

Figures & data

Table 1. Demographic data, lung function parameters, NPPV settings (n = 15)

		Mean	SD
Age	[yrs]	61.4	6.7
BMI	[kg·m-2]	26.2	5.7
VC	[l]	2.3	0.8
VC	[% pred]	50.6	18.6
FEV1	[l]	1.0	0.5
FEV1	[% pred]	29.9	15.9
TLC	[% pred]	109.8	22.1
RV	[% pred]	249.4	97.3
NPPV settings
		Mean	SD
IPAP	[mbar]	28.2	4.8
EPAP	[mbar]	5.5	1.5
FB	[/min]	17.3	2.6
Tinsp	[s]	1.0	0.1

BMI: body mass index; VC: vital capacity; % pred: % predicted; FEV1: forced expiratory voume in 1 second; TLC: total lung capacity; NPPV: non-invasive positive pressure ventilation; IPAP: inspiratory positive airway pressure; EPAP: expiratory positive airway pressure; FB: breathing frequency; Tinsp: inspiration time.

Table 2. Blood gases, cardiac frequency, blood pressure, dyspnea and walking distance before and after the 6-min walking test (6MWT); n = 10

		6MWT-O2	6MWT-NPPV	p-value
Before 6MWT
PO2	[mmHg]	67.3 ± 11.2	66.8 ± 7.2	p = 0.9
PCO2	[mmHg]	50.9 ± 8.1	50.6 ± 7.5	p = 0.9
SO2	[%]	94.2 ± 3.6	93.9 ± 3.1	p = 0.7
pH		7.40 ± 0.03	7.39 ± 0.03	p = 0.2
fc	[/min]	83.4 ± 16.3	87.7 ± 18.1	p = 0.1
SPB	[mmHg]	121.6 ± 15.7	124.2 ± 12.7	p = 0.6
DBP	[mmHg]	77.0 ± 13.0	77.6 ± 13.0	p = 0.9
BDS		0.75 (0.0–3.0)	0.25 (0.0–2.0)	p = 0.3
Blood Lactate	[mmol/l]	1.0 ± 0.4	1.2 ± 0.4	p = 0.4
After 6MWT
PO2	[mmHg]	65.6 ± 12.0	55.5 ± 10.6	p = 0.001
PCO2	[mmHg]	54.3 ± 10.0	53.0 ± 7.1	p = 0.6
SO2	[%]	89.2 ± 7.5	83.9 ± 6.0	p = 0.043
pH		7.37 ± 0.04	7.36 ± 0.05	p = 0.4
fc	[/min]	105.4 ± 21.1	106.3 ± 18.4	p = 0.6
SPB	[mmHg]	140.4 ± 23.1	138.3 ± 16.1	p = 0.6
DBP	[mmHg]	77.8 ± 15.7 *	86.5 ± 7.9	p = 0.4
BDS		5.5 (3.75–9.0)	8.0 (4.0–10.0)	p = 0.5
Blood Lactate	[mmol/l]	1.3 ± 0.8	2.0 ± 1.3	p = 0.2
6MWD	[m]	377 ± 108	318 ± 160	p = 0.08

Data are presented as mean ± SD or median (interquartile range). 6MWT: Six-minute walk test; 6MWT-O2:Six-minute walk test with supplemental oxygen; 6MWT-NPPV: Six-minute walk test with non-invasive positive pressure ventilation; PO2: partial ­pressure of oxygen; PCO2: partial pressure of carbon dioxide; SO2: arterial saturation; fc: cardiac frequency; SPB: systolic blood pressure; DBP: diastolic blood pressure; BDS: Borg dyspnea scale; 6MWD: 6-minute walking distance. *n = 8.

Figure 1. Partial arterial oxygen pressure (PO2) before and after (A) a 6-minute walk test with supplemental oxygen (6MWT-O2) and (B) a 6-minute walk test with non-invasive positive pressure ventilation without supplemental oxygen (6MWT-NPPV). n.s. = not significant.

Figure 2. Differences in 6-minute walking distance in a 6-minute walk test with supplemental oxygen (6MWT-O2) and with non-invasive positive pressure ventilation without supplemental oxygen (6MWT-NPPV).