A Randomised Crossover Trial Comparing Volume Assured and Pressure Preset Noninvasive Ventilation in Stable Hypercapnic COPD

Figures & data

Figure 1.  Trial Protocol

Table 1.  Mean (SD) daytime arterial blood gases, nocturnal ventilatory indices, lung function, exercise capacity and demographic data prior to treatment with pp-NIPPV and at trial enrollment

Variable	Historical pre-treatment data	Value at enrollment	Number at enrolment
Age (years)	62 (10)	65 (9.2)	24
BMI (kg/m^2)	NA	31.5 (9.5)	24
FEV1(l)	0.65 (0.3)	0.6 (0.3)	24
FEV1(% predicted)	25 (10)	24 (9)	24
FVC (l)	1.95 (0.8)	2.1 (1)	24
FVC (% predicted)	60 (18)	65 (17)	24
TLC (l)	NA	7.2 (2.3)	20
TLC (% predicted)	NA	124 (22)	20
RV (l)	NA	4.98 (1.5)	20
RV (% predicted)	NA	227(72)	20
TLCO (mmolCO/kPa/min)	NA	4.2 (1.5)	11
TLCO (% predicted)	NA	48 (16)	11
pH*	7.41 (.04)	7.39 (.04)	24
PaO2 (kPa)*	6.8 (1.2)	8.1 (1.1)	24
PaCO2 (kPa)*	8.5 (1.2)	6.7 (1.1)	24
HCO3−(mmol/l)*	NA	30.5 (3.8)	24
Mean nocturnal SpO2	80 (6)	90.2 (2.7)	24
Mean nocturnal PtcCO2	8.5 (1.2)	6.1 (1.5)	23
Exercise tolerance SWT(m)	NA	156 (103)	21
SGRQ total score	NA	59 (12)	24

*= self ventilating on usual oxygen flow rate.

Abbreviations: BMI: body mass index; FEV₁: forced expiratory volume in one second; FVC: forced vital capacity; TLC: total lung capacity; RV: residual volume; TLCO: total lung carbon monoxide uptake; PaO₂: partial pressure of arterial oxygen; PaCO₂: partial pressure of arterial carbon dioxide; HCO₃-: bicarbonate; SpO₂: oxygen saturation; PtcCO₂: partial pressure of transcutaneous carbon dioxide; SGRQ: St George's Respiratory Questionnaire; SWT: shuttle walk test; NA: not available. Pre-treatment data were collected retrospectively from the trial subjects’ hospital records.

Table 2.  Mean (SD) daytime arterial blood gases, nocturnal ventilatory indices, lung function and exercise capacity following 8 weeks each of va-NIPPV and pp-NIPPV.

Outcome	Va-NIPPV	Pp-NIPPV	p	Number
pH	7.39 (0.05)	7.39 (0.04)	0.67	24
PaO2 (kPa)	7.8 (1.2)	8.1 (1)	0.17	24
PaCO2 (kPa)	6.7 (1.1)	6.3 (1.2)	0.05*	24
HCO3−(mmol/l)	30.5 (4.8)	29.2 (4.5)	0.06	24
mSpO2 (%)	89.8 (4)	91.3 (2.8)	0.02*	24
mPtcCO2 (kPa)	6.3 (1.4)	6.2 (1.5)	0.78	21
FEV1 (l)	0.67 (0.3)	0.64 (0.28)	0.38	23
FEV1 (%)	27 (10)	25 (9)	0.29	23
FVC (l)	2.3 (1)	2.21 (1)	0.51	23
FVC%	69 (24)	69 (21)	0.8	23
TLC (l)	7.2 (2.2)	7.3 (2.4)	0.6	16
TLC%	123 (24)	126 (31)	0.5	16
RV (l)	4.7 (1.6)	4.8 (1.8)	0.69	16
RV (%)	215 (80)	219 (80)	0.7	16
TLCO(mmolCO/kPa/min)	4.1 (1.8)	4.3 (2)	0.45	12
TLCO (%)	49 (18)	54 (26)	0.35	12
Exercise Tolerance SWT (m)	173 (97)	170 (107)	0.87	18

*= Not significant when corrected for multiple end points.

Abbreviations: PaO₂: partial pressure of arterial oxygen; PaCO₂: partial pressure of arterial carbon dioxide; HCO₃−: bicarbonate; mSpO₂: mean nocturnal oxygen saturation; mPtcCO₂: mean nocturnal partial pressure of transcutaneous carbon dioxide; FEV₁: forced expiratory volume in one second; FVC: forced vital capacity; TLC: total lung capacity; RV: residual volume; TLCO: total lung carbon monoxide uptake; SWT: shuttle walk test.

Table 3.  Mean (SD) of health status and visual analogue scores following 8 weeks each of va-NIPPV and pp-NIPPV

Outcome	Va-NIPPV	Pp-NIPPV	P
SF-36
Physical function	27 (23)	28 (22)	0.93
Role physical	63 (20)	60 (21)	0.6
Body pain	68 (25)	71 (21)	0.51
General health	32 (18)	35 (18)	0.2
Physical component score	39 (11)	39 (8)	0.76
Vitality	41 (19)	42 (16)	0.82
Social functioning	57 (28)	56 (29)	0.86
Role emotional	79 (24)	74 (22)	0.28
Mental health	76 (19)	77 (18)	0.78
Mental component score	54 (12)	53(10)	0.73
SGRQ
Symptoms	62 (17)	62 (13)	0.82
Activities	78 (18)	83 (13)	0.15
Impacts	39 (14)	44 (13)	0.07
Total score	55 (13)	59 (10)	0.08
VAS
Ease of use	87 (13)	87 (19)	1
Tolerability	87 (14)	81 (20)	0.19
Comfort	77 (23)	73 (23)	0.31
Sleep quality	78 (22)	73 (27)	0.34

Abbreviations: SF-36: short form 36; SGRQ: St George's Respiratory Questionnaire; VAS: visual analogue score.