Spontaneous-timed versus controlled noninvasive ventilation in chronic hypercapnia – a crossover trial

Figures & data

Figure 1 Consort chart.

Abbreviation: NIV, noninvasive ventilation.

Table 1 Ventilator settings

Diagnosis	N	Pinsp	Pexp	RR (ST)	Ti(%) (ST)	Trig_i	Trig_e	RR TA	RR TA range
COPD	26	21±2.7	5.8±1	11.3±1.8	33.5±1.2	4.8±1.3	2.8±1.2	17.3±2.1	6±1.1
OHS	7	23.9±3.3	7±1.7	11.9±2	33±0	4.3±1.1	2.6±1.1	16.9±1.9	6±1.2
Scoliosis	6	18.2±4.1	5±1.1	11.5±0.8	33±0	4.8±0.4	2±0.6	19.5±4.5	7±2.5
Other	3	19.7±5.1	4.7±1.2	11.3±1.2	37±0.3	4.3±0.6	2.7±2.1	19.3±6	6±3.5

Abbreviations: Pinsp, inspiratory pressure (cmH₂O); Pexp, expiratory pressure (cmH₂O); RR, respiratory rate per minute; Ti(%)(ST), inspiratory time during ST mode in % of duty cyle; Trig_i, inspiratory trigger; Trig_e, expiratory trigger; RR TA, respiratory rate set point during TA ventilation; RR TA range, range allowance for TA mode ventilation.

Table 2 Patient diseases, BMI, walking distance and pulmonary function tests

Diagnosis	N	BMI	6MWD	FeV1%	VC%	RV/TLC%	MIP
COPD	26	27.7±5.5	369±79	29±8	52±11	183±21	44±19
OHS	7	37.9±5	381±53	60±20	63±18	117±33	41±21
Scoliosis	6	26±5.8	453±54	44±18	48±15	158±21	40±17
Other	3	23.4±6.1	385±182	42±13	38±7	94±6.5	42±20

Abbreviations: OHS, obesity hypoventilation syndrome; OTH, other diseases (post tuberculosis (N=1) and diaphragmatic paralysis (N=2)); BMI, body mass index; 6MWD, 6- minute walking distance; FeV₁%, forced vital capacity in one second (percent predicted); VC, inspiratory vital capacity (percent predicted); RV/TLC%, ratio of residual volume to total lung capacity (percent predicted); MIP, maximal inspiratory pressure (cm H₂O).

Table 3 Patient diseases and daytime ABG

Diagnosis	N	PO2	PCO2	pH	HCO3
COPD	26	60±11.9	54±6.7	7.39±0.02	31.6±3.6
OHS	7	67±6.5	48.8±10.6	7.44±0.06	31.8±4.1
Scoliosis	6	65±14	46.8±6.3	7.42±0.04	29.7±1.9
Other	3	62±14	52.6±3	7.39±0.02	31.1 ± 1

Abbreviations: ABG, blood gas analysis; OHS, obesity hypoventilation syndrome; OTH, other diseases (post tuberculosis (N=1) and diaphragmatic paralysis (N=2)); PO₂, partial pressure of oxygen (mmHg); PCO₂, partial pressure of carbon dioxide (mmHg); HCO₃, bicarbonate (mmol/L).

Figure 2 Mean CO₂ values at night and during the day before and after 6 weeks of ST-mode and controlled NIV.Abbreviation: NIV, noninvasive ventilation.

Figure 3 Mean HCO₃ values at night and during the day before and after 6 weeks of ST-mode and controlled NIV.

Abbreviation: NIV, noninvasive ventilation.

Figure 4 Mean CO₂ values at night and during the day before and after 6 weeks of ST-mode and controlled NIV (COPD patients only).

Abbreviation: NIV, noninvasive ventilation.

Figure 5 Mean HCO₃ values at night and during the day before and after 6 weeks of ST-mode and controlled NIV (COPD patients only).Abbreviation: NIV, noninvasive ventilation.

Table 4 Lung function parameters before and after treatment periods

Parameter	Group	Before NIV	After NIV	p-value
VC (% predicted)	ST	55.8±14.4	56.2±15.7	0.45
	TA	52.2±14.8	57.1±15.4	0.07
FeV1 (% predicted)	ST	39.8±17.2	40.4±17.7	0.43
	TA	37.3±15.9	42.0±18.4	0.11
MIP (cm H2O)	ST	44.6±16.9	46.2±19.2	0.34
	TA	41.4±16.5	43.9±18.2	0.26

Abbreviations: ST, ST mode; TA, TA mode; VC, vital capacity; FeV₁, forced vital capacity in one second; MIP, maximal inspiratory pressure; NIV, noninvasive ventilation.