The Effects of Withdrawing Long-Term Nocturnal Non-Invasive Ventilation in COPD Patients

Figures & data

Table 1.  Historical ABG and lung function data prior to NIPPV (mean (SD))

pH	PaCO2 kPa	PaO2 kPa	FEV1(L)	FEV1(%)	FVC(L)	FVC(%)	TLC(L)	TLC(%)
7.4 (0.05)	8.5 (0.9)	6.7 (1)	0.79 (0.3)	29 (13)	2.4 (0.6)	70 (17)	7 (1.5)	121 (20)

Abbreviations: PaCO₂: partial pressure of arterial carbon dioxide; PaO₂: partial pressure of arterial oxygen; FEV₁: Forced expiratory volume in 1 second; FVC: forced vital capacity; TLC: total lung capacity.

Table 2.  Values at trial entry

Patient	Age	BMI	PaO2	PaCO2	HCO3-	FEV1	FVC	MIP	MEP	Ex. Tol.
Number	years	kg/m^2	kPa	kPa	mmol/L	L	L	cmH2O	cmH2O	M
1	53	24.9	10.9	5.3	27.8	0.58	2.59	65	191	220
2	57	18.8	7.2	6.5	28.3	0.45	1.08	10	94	30
3	56	37.4	7.7	7.5	28.2	0.78	2.23	32	146	180
4	59	40.6	9.9	4.8	23.9	1.44	2.38	29	69	150
5	69	33.8	9.3	5.9	28.5	1.11	2.7	NA	60	310
6	64	31.1	8.7	7.6	38	0.45	1.6	26	102	80
7	60	36.2	7.6	7.1	32.1	1.19	2.66	52	153	360
8	79	27.1	8	6.5	31.1	0.64	2.11	38	117	NA
9	72	25.4	6.3	7.7	37.6	0.82	1.45	46	53	140
10	71	32.6	6.7	6.9	27.4	0.95	2.75	70	131	100
Mean (SD)	64 (8)	30.9 (6.7)	8.3 (1.4)	6.6 (1)	30.3 (4.5)	0.84 (0.3)	2.2 (0.6)	41 (19)	112 (45)	174 (107)

NA = patient unable to perform test.

Abbreviations: NA: patient unable to perform test; BMI: body mass index; PaO₂: partial pressure of arterial oxygen; PaCO₂: partial pressure of arterial carbon dioxide; HCO₃-: Bicarbonate; FEV₁: forced expiratory volume in one second; FVC: forced vital capacity; MIP: maximal inspiratory pressure; MEP: maximal expiratory pressure; Ex. Tol: exercise tolerance.

Table 3.  Comparison in outcome variables between 1st and 7th day of withdrawal (n = 10)

Variable (units)	1st day	7th day	p-value
	Mean (SD)	Mean (SD)
PaO2 (kPa)	8.25 (1.4)	8.15 (0.9)	0.7
PaCO2 (kPa)	6.6 (1)	6.9 (0.8)	0.08
pH	7.4 (0.05)	7.4 (0.04)	0.8
HCO3- (mmol/L)	30.3 (4.5)	31.2 (3.9)	0.04
FEV1 (L)	0.84 (0.3)	0.87 (0.4)	0.7
FVC (L)	2.16 (0.6)	2.16 (0.6)	1.0
MIP (cm H2O)	37 (22)	37 (23)	0.9
MEP (cm H2O)	112 (45)	119 (44)	0.5
Exercise Tolerance (metres)	174 (107)	166 (103)	0.5
Mean overnight SpO2 (%)	93 (4)	93 (3)	0.8
Mean overnight PtcCO2 (kPa)	6.3 (1)	7.6 (1.1)	0.04
Minimum overnight SpO2 (%)	81 (9)	79 (9)	0.2

Abbreviations: PaO₂: partial pressure of arterial oxygen; PaCO₂: partial pressure of arterial carbon dioxide; HCO₃: bicarbonate; FEV₁: forced expiratory volume in one second; FVC: forced vital capacity; MIP: maximal inspiratory pressure; MEP: maximal expiratory pressure; SpO₂: arterial oxygen saturations; PtcCO₂: partial pressure of transcutaneous carbon dioxide.

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