Clinical impact of episodic nocturnal hypercapnia and its treatment with noninvasive positive pressure ventilation in patients with stable advanced COPD

Figures & data

Figure 1 Flowchart of patient recruitment.

Abbreviations: NPPV, noninvasive positive pressure ventilation; CPAP, continuous positive airway pressure; PtcCO₂, transcutaneous carbon dioxide tension; PaCO₂, arterial carbon dioxide pressure.

Figure 2 Definition of the study period.

Abbreviations: eNH, episodic nocturnal hypercapnia; NPPV, noninvasive positive pressure ventilation; PtcCO₂, transcutaneous carbon dioxide tension; BNP, brain natriuretic peptide; PA, pulmonary arterial diameter; A, aortic diameter.

Figure 3 (A) SpO₂ monitoring during sleep before NPPV, (B) SpO₂ monitoring during sleep after NPPV, (C) PtcCO₂ monitoring during sleep before NPPV, (D) PtcCO₂ monitoring during sleep after NPPV.

Notes: Before NPPV, nocturnal SpO₂ and PtcCO₂ monitoring showing episodic oxygen desaturations and episodic elevated PtcCO₂. After NPPV, episodic oxygen desaturations and episodic elevated PtcCO₂ were improved.
Abbreviations: NPPV, noninvasive positive pressure ventilation; SpO₂, saturation of pulse oximetry; PtcCO₂, transcutaneous carbon dioxide tension.

Table 1 Patient characteristics at visit 1

Variable	All (n=21)	Non-eNH (n=11)	eNH (n=10)	p-value
Age, years	69.5±1.8	67.5±2.0	71.8±2.8	0.241
Male sex, %	91	91	90	0.738
Body mass index, kg/m^2	20.1±0.8	21.1±3.3	18.9±1.3	0.199
Smoking history, pack-years	85.3±13.3	68.6±9.5	78.2±24.7	0.468
Current smoker, %	0	0	0	1.000
Long-term oxygen therapy, %	19	9	30	0.256
FEV1, % of predicted value	26.9±2.0	23.6±2.2	30.5±2.8	0.078
FVC, % of predicted value	76.7±3.4	78.7±5.6	74.9±3.2	0.557
FEV1/FVC, ratio	28.7±2.0	24.5±1.7	33.3±3.2	0.030
Hematocrit, %	41.6±1.2	43.2±1.7	40.1±1.7	0.242
pH	7.42±0.01	7.43±0.01	7.41±0.01	0.085
PaCO2, mmHg	44.5±1.4	42.0±1.7	47.2±1.9	0.070
PaO2, mmHg	74.5±2.2	74.1±3.0	75.0±3.2	0.851
Bicarbonate, mmol/L	28.5±0.8	27.4±0.8	29.7±1.3	0.786
Albumin, g/dL	4.2±0.1	4.4±0.1	4.0±0.1	0.027
BNP, pg/mL	86.5±29.3	18.0±4.3	144.0±53.6	0.064
mMRC	2.7±0.2	2.5±0.2	2.9±0.2	0.268
COPD assessment test	23.6±1.7	23.1±1.8	24.2±3.0	0.766
Ejection fraction, %	59.0±1.6	58.3±2.1	59.7±2.5	0.681
Estimated PASP, mmHg	41.1±3.3	33.6±2.6	47.0±4.8	0.037
Pulmonary arterial diameter, cm	2.9±0.12	2.6±0.12	3.2±0.17	0.045
Aortic diameter, cm	3.3±0.07	3.3±0.11	3.3±0.09	0.599
PA:A ratio	0.88±0.03	0.79±0.03	0.96±0.05	0.019
The frequency of acute exacerbations, times/year	1.8±0.5	0.8±0.2	2.8±0.8	0.036

Note: Data are presented as mean ± SE.

Abbreviations: eNH, episodic nocturnal hypercapnia; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; PaCO₂, arterial carbon dioxide pressure; PaO₂, arterial oxygen pressure; mMRC, modified medical research council dyspnea scale; BNP, brain natriuretic peptide; mMRC, modified medical research council dyspnea scale; PASP, pulmonary artery systolic pressure; PA, pulmonary arterial diameter; A, aortic diameter.

Figure 4 Time course of serum albumin levels in patients with and without eNH. Notes: Serum albumin levels in patients with eNH showing gradual decrease in period A. Serum albumin levels in patients with eNH showing improvement in period B. Data are presented as mean ± SE.

Abbreviations: eNH, episodic nocturnal hypercapnia; NPPV, noninvasive positive pressure ventilation.

Figure 5 Time course of daytime partial carbon dioxide pressure posterior to long-term noninvasive positive pressure ventilation. Data are presented as mean ± SE.

Figure 6 Comparison of the frequency of exacerbations between before and after noninvasive positive pressure ventilation. Data are presented as mean ± SE.

Table S1 Setting of episodic nocturnal hypercapnia targeted noninvasive positive pressure

Intelligent volume-assured pressure support mode
	EPAP cmH2O	Minimum PSV cmH2O	Maximum PSV cmH2O	Target alveolar ventilation L/min	RR breaths/min	Oxygenation L/min	Average of daily used h min/day
No 1	5	4	10	4.2	18	1	564
No 2	4	4	8	5.2	20	0	443
No 3	4	4	7	4.7	20	0	423
No 4	7	3	15	5.8	16	0	488
No 5	4	4	10	4.6	20	0	319
No 6	7.4	2	6	5.5	15	0	337
No 7	4	2	12	5	15	0	331
Bi-level positive airway pressure with fixed-level pressure support mode
	EPAP cmH2O	IPAP cmH2O	RR breaths/min	Oxygenation L/min	Average of daily used h min/day
No 8	5	9	18	0.5	453
No 9	7	10	21	3	423
No 10	8	14	14	0	503

Abbreviations: EPAP, expiratory positive airway pressure; PSV, pressure support ventilation; IPAP, inspiratory positive airway pressure; RR, respiratory rate.