Sleep Hypoventilation is Common in Diurnal Normocapnic COPD Patients with Severe or Very Severe Obstruction and is Not Associated with Body Mass Index

Figures & data

Table 1. Characteristics of the study participants. Data are presented as mean (SD) unless otherwise stated.

	NW	OW	OB	Total group	P between groups	P NW vs OW	P NW vs OB	P OW vs OB
N	17	18	21	56	–	–	–	–
Age, mean	63.1 (9.6)	68.4 (5.5)	67.0 (8.0)	66.3 (8.0)	0.13	–	–	–
Sex, % males	47	61	43	50	0.50	–	–	–
Weight, kg	64.6 (7.6)	79.1 (9.0)	90.6 (10.9)	79.0 (14.2)	<0.01	<0.01	<0.01	<0.01
Hight, cm	170 (8)	168 (7)	167 (10)	168 (9)	0.45	–	–	–
BMI	22.3 (1.7)	28.0 (1.3)	32.5 (1.2)	28.0 (4.5)	<0.01	<0.01	<0.01	<0.01
Hip circumference, cm	92 (5)	100 (7)	108 (11)	101 (11)	<0.01	<0.01	<0.01	0.02
Waist circumference, cm	90 (6)	105 (9)	114 (9)	104 (13)	<0.01	<0.01	<0.01	<0.01
Waist/hip ratio	0.98 (0.08)	1.06 (0.12)	1.07 (0.13)	1.04 (0.11)	0.05	–	–	–
Fat, %	31 (8)	36 (7)	42 (7)	37 (9)	<0.01	0.12	<0.01	0.10
FFMI, kg/m2	15.3 (2.3)	17.8 (2.4)	19.0 (2.3)	17.5	<0.01	<0.01	<0.01	0.40
Smoked pack years	37 (23)	41 (30)	33 (16)	37 (23)	0.57	–	–	–
Smoking status
% current smokers	41	28	5	23	0.02	0.40	0.01	0.08
Use of inhalers
% using SABA	71	61	61	64	0.80	–	–	–
% using SAMA	6	17	10	11	0.58	–	–	–
% using LABA	100	94	95	96	0.47	–	–	–
% using LAMA	100	83	86	89	0.10	–	–	–
% using ICS	82	78	76	79	0.89	–	–	–
Comorbidities
% Diabetes	0	22	14	13	0.05	–	–	–
% Hypertension	18	50	48	39	0.09	–	–	–
% Atrial fibrillation	12	6	5	7	0.69	–	–	–
% Myocardial infarction	0	17	10	9	0.12	–	–	–
% Congestive heart failure	0	0	0	0	–	–	–	–

Abbreviations: BMI, body mass index; FFMI, free fat mass index; SABA, short-acting beta agonist; SAMA, short-acting muscarinic antagonist; LABA, long-acting beta agonist; LAMA, long-acting muscarinic antagonist; ICS, inhaled corticosteroid.

Table 2. Pulmonary function tests. Data are presented as mean (SD) unless otherwise stated.

	NW	OW	OB	Total group	P between groups	P NW vs OW	P NW vs OB	OW vs OB
FEV1, % pred	32.2 (8.5)	38.1 (6.6)	43.9 (9.5)	38.5 (9.5)	<0.01	0.13	<0.01	0.10
FEV1, L	0.90 (0.35)	0.96 (0.20)	1.08 (0.35)	0.99 (0.31)	0.21	–	–	–
VC, % pred	88.5 (18.6)	93.4 (15.2)	94.6 (17.8)	92.4 (17.1)	0.53	–	–	–
VC, L	3.15 (0.99)	3.14 (0.84)	3.02 (0.92)	3.10 (0.90)	0.89	–	–	–
IC, % pred	81.9 (18.9)	88.9 (13.1)	98.0 (19.8)	90.2 (18.6)	0.03	0.74	0.02	0.35
IC, L	2.14 (0.67)	2.19 (0.52)	2.30 (0.73)	2.22 (0.64)	0.72	–	–	–
FRC, % pred	191.6 (29.1)	162.9 (28.7)	155.3 (21.3)	168.3 (30.0)	<0.01	<0.01	<0.01	1.00
FRC, L	6.05 (1.16)	5.16 (1.08)	4.74 (1.04)	5.26 (1.20)	<0.01	0.06	<0.01	0.70
ERV, % pred	107.7 (33.4)	106.7 (39.9)	87.1 (39.6)	99.7 (38.5)	0.17	–	–	–
ERV, L	1.02 (0.42)	0.94 (0.44)	0.72 (0.35)	0.88 (0.41)	0.06	–	–	–
RV, % pred	227.9 (42.6)	203.2 (45.3)	185.3 (31.0)	203.1 (42.4)	0.01	0.24	<0.01	0.49
RV, L	5.11 (1.03)	4.61 (0.90)	4.04 (0.67)	4.53 (0.95)	<0.01	0.30	<0.01	0.13
TLC, % pred	130.9 (15.5)	121.6 (17.9)	120.3 (13.8)	123.8 (16.1)	0.11	–	–	–
TLC, L	7.82 (1.38)	7.09 (1.29)	6.77 (1.41)	7.18 (1.41)	0.07	–	–	–
RV/TLC, %	65.9 (11.7)	65.6 (10.0)	60.7 (7.9)	63.8 (9.9)	0.19	–	–	–
DLCO SB, % pred	46.5 (12.1)	53.7 (15.2)	55.7 (11.4)	52.3 (13.3)	0.10	–	–	–
DLCO/VA, % pred	56.6 (14.7)	64.4 (18.3)	71.6 (20.9)	64.8 (19.1)	0.06	–	–	–
PcCO2, mmHg	40.3 (3.2)	41.4 (3.9)	41.3 (4.5)	41.0 (3.9)	0.67	–	–	–

Abbreviations: FEV₁, forced expiratory volume in 1 s; VC, vital capacity; TLC, total lung capacity; FRC, functional residual capacity; ERV, expiratory reserve volume; RV, residual volume; DLCO, diffusing capacity for carbon monoxide; VA, alveolar volume; PcCO₂, capillary pCO₂.

Table 3. Polysomnography and sleep hypoventilation. Data are presented as mean (SD) unless otherwise stated.

	NW	OW	OB	Total group	P between groups
TST, min	369 (87)	380 (56)	391 (62)	381 (68)	0.63
Sleep efficiency, % TST/PST	64.5 (13.5)	66.3 (8.3)	69.3 (8.7)	66.9 (10.3)	0.36
% REM of TST	15.3 (7.6)	16.9 (6.4)	17.2 (7.6)	16.6 (7.1)	0.69
AI, events/hour, mean	0.65 (1.6)	0.67 (1.3)	0.81 (1.1)	0.71 (1.3)	0.92
AHI, events/hour, mean	10.2 (5.4)	9.9 (5.4)	11.1 (6.6)	10.4 (5.8)	0.81
MeanSpO2 during sleep	90.3 (2.1)	89.6 (2.2)	88.8 (3.1)	89.5 (2.6)	0.21
Lowest SpO2 during sleep	81.5 (5.2)	79.6 (7.1)	81.1 (5.5)	80.8 (5.9)	0.58
Mean sleep PtcCO2, mmHg	53.4 (4.9)	54.6 (5.8)	54.9 (6.4)	54.3 (5.7)	0.70
Highest PtcCO2, mmHg	58.5 (6.4)	60.3 (6.0)	60.5 (7.7)	59.8 (6.8)	0.62
Highest PtcCO2 REM, mmHg	59.9 (6.5)	60.1 (6.3)	60.5 (7.8)	60.2 (6.8)	0.96
Δ PtcCO2 Mean, mmHG	5.4 (2.9)	6.8 (4.0)	6.5 (3.7)	6.3 (3.6)	0.49
Δ PtcCO2 Max, mmHG	10.5 (4.3)	12.5 (4.2)	12.1 (4.8)	11.8 (4.5)	0.40
Sleep hypoventilation, %	64.7	66.7	66.7	66.1	0.99

Abbreviations: TST, total sleep time; REM, rapid eye movement sleep; AI, arousal index; AHI, apnea/hypopnea index; SpO2, oxygen saturation; P_tcCO₂, transcutaneous pCO₂; Δ P_tcCO₂ Mean, delta P_tcCO₂ between awake and mean P_tcCO₂ during sleep; Δ P_tcCO₂ Max, delta P_tcCO2 between awake and highest P_tcCO₂ during sleep.