A randomized clinical trial of neurally adjusted ventilatory assist versus conventional weaning mode in patients with COPD and prolonged mechanical ventilation

Figures & data

Table 1 Patient characteristics

Variables	NAVA (n=14)	Conventional (n=19)	P-value
Sex n(%)
Male	11 (78.6%)	13 (68.4%)	0.51
Female	3 (21.4%)	6 (31.6%)
Age, years	79.3±6.2	76.9±9.3	0.62
IBW (Kg)	53.6±11.2	55.7±1.7	0.82
Total ICU, days	19.4±11.8	22.3±19.4	0.08
Ventilator days before	26.9±10.7	27.1±13.0	0.41
PFT (before admission)
FEV1/Pred (%)	59.0±15.5	53.5±16.5	0.51
FEV1/FVC (%)	64.8±18.8	71.9±17.7	0.12
SOFA score	3.7±2.8	4.3±2.5	0.32
APACHE II
Mean	17.4±4.1	18.7±5.0	0.42
≥15	10 (71.4%)	15 (78.9%)	0.59
Acute lung injury
Sepsis	0 (0%)	15.3%	0.38
Bacterial pneumonia	6 (42.9%)	6 (31.6%)	0.50
ICU ventilator data
TV (mL)	415.9±128.7	511.0±79.9	0.02
TV of IBW (mL/kg)	6.8±1.9	9.4±1.4	0.01
RR, breath/min	23.3±5.5	19.7±6.4	0.05
MV (L)	9.0±2.7	9.3±2.3	0.89
RSBI	64.1±28.9	80.9±38.0	0.42
Respiratory muscle strength
MIP (cmH2O)	22.9±9.3	26.4±9.0	0.35
MEP (cmH2O)	25.5±14.3	26.9±18	0.73
Nutrition
ALB (3.5–5 g/dL)	2.6±9.3	2.7±9.3	0.68

Notes: Pearson chi-square test was used for sex, Student’s t-test was used for age, body weight, total ICU days, ventilator days before included, and nonparametric method for APACHE II and nutrition. Data is presented as either n(%) or mean ± SD.

Abbreviations: IBW, ideal body weight; PFT, pulmonary function test; TV, tidal volume; RR, respiratory rate; MV, minute volume; RSBI, rapid shallow breathing index; MIP, maximum inspiratory pressure; MEP, maximum expiratory pressure; NAVA, neutrally adjusted ventilatory assist; ICU, intensive care unit; FEV₁/pred, predicted forced expiratory volume in 1 second; FEV₁/FVC, forced expiratory volume in 1 second/forced vital capacity; APACHE II, Acute Physiology and Chronic Health Enquiry II; ALB, albumin; SOFA, Sequential Organ Failure Assessment.

Table 2 Clinical data collection by T0, T1, T2a

Variables	NAVA (n=14)		Conventional (n=19)		P-value
T0: data immediately post-Edi catheter insertion
TV (mL)	424.9	±102.4	448.9	±100.6	0.71
TV of IBW (mL/kg)	7.1	±1.9	8.3	±1.9	0.09
RR, breath/min	22.3	±5.2	22.8	±7.3	0.21
MV (L)	9.7	±2.1	9.4	±2.1	0.78
TV/Edi (NVE)	71.9	±41.9	92.9	±66.9	0.48
RSBI	64.1	±28.9	80.9	±38.0	0.42
MIP (cmH2O)	20.0	±1.0	20.5	±9.3	0.71
MEP (cmH2O)	14.0	±0.1	21.5	±10.6	0.46
P0.1, cmH2O	1.1	±1.0	1.0	±1.1	0.81
PEEPi, cmH2O	2.3	±3.4	3.9	±3.7	0.27
ALB (3.5–5 g/dL)	1.7	±1.5	2.4	±0.5	0.23
T1: data after intervention
Ventilator data
TV (mL)	435.7	±109.3	463.3	±104.3	0.42
TV of IBW (mL/kg)	7.2	±1.8	8.5	±1.8	0.05
RR, breath/min	26.0	±6.7	23.2	±8.7	0.23
MV (L)	10.5	±2.0	10.2	±3.2	0.68
TV/Edi (NVE)	74.7	±54.9	89.5	±70.1	0.71
RSBI	91.6	±57.9	127.1	±141.3	0.55
MIP (cmH2O)	25.4	±12.6	26.0	±14	0.96
MEP (cmH2O)	32.0	±20.2	26.1	±24	0.21
P0.1, cmH2O	1.2	±1.7	1.1	±0.9	0.84
PEEPi, cmH2O	2.4	±4.9	2.7	±3.6	0.77
ALB (3.5–5 g/dL)	1.7	±1.5	2.4	±0.5	0.51
T2: data at the end of SBT trial
TV (mL)	373.8	±80.9	391.6	±87.7	0.67
TV of IBW (mL/kg)	6.1	±1.1	7.2	±1.6	0.05
RR, breath/min	24.7	±4.7	25.7	±8.7	0.87
MV (L)	8.9	±2.1	9.4	±2.3	0.51
TV/Edi (NVE)	54.0	±52.5	54.4	±49.9	0.86
RSBI	104.6	±54.2	129.6	±120.7	0.87
MIP (cmH2O)	30.9	±12.6	26.7	±11.1	0.42
MEP (cmH2O)	31.6	±17.8	25.9	±23.2	0.16
ALB (3.5–5 g/dL)	2.5	±0.7	3.0	±0.1	0.31

Notes:

a Nonparametric method. Data presented as mean ± standard deviation.

Abbreviations: IBW, ideal body weight; NAVA, neutrally adjusted ventilatory assist; TV, tidal volume; RR, respiratory rate; MV, minute volume; RSBI, rapid shallow breathing index; MIP, maximum inspiratory pressure; MEP, maximum expiratory pressure; Edi, diaphragm electrical activity; NVE, tidal volume/neuro-ventilatory efficiency; PEEPi, intrinsic positive end-expiratory pressure; SBT, spontaneous breathing trial; ALB, albumin; p0.1, negative airway pressure generated during the first 100 msec of an occluded inspiration.

Figure 1 Flowchart of registered patients.

Abbreviations: NAVA, neurally adjusted ventilatory assist; PSV, pressure-support ventilation; Edi, diaphragm electrical activity; PEEP, positive end-expiratory pressure.

Figure 2 Asynchrony recognition rate before and after Edi catheter insertion.

Notes: Frequencies and Pearson’s chi-squared test. *P<0.05; **P<0.01; ***P<0.001.
Abbreviation: Edi, diaphragm electrical activity.

Table 3 Asynchrony index between NAVA and control group (n=33)

Variables n(%)	NAVA (n=14)	Conventional (n=19)	P-value
Asynchrony index	0	16(84.2)	<0.001
Asynchrony incidence	0	16(84.2)	<0.001
Ineffective trigger	0	10(52.6)	<0.001
Delayed trigger	0	7(36.8)	<0.001
Flow asynchrony	0	5(26.3)	<0.001
Double triggering	0	4(21.1)	<0.001
Auto triggering	0	0/0	–
Premature cycling	0	0/0	–
Delayed cycling	0	0/0	–

Abbreviation: NAVA, neurally adjusted ventilatory assist.

Table 4 Weaning outcome after NAVA and conventional mode

Variables, total (n=33)	NAVA (n =14)		Conventional (n=19)		P-value
RCC mortality (%)	1	(7.1)	6	(31.6)	0.09
90 days mortality (%)	4	(28.6)	6	(31.6)	0.94
Total RCC days	20.3	±12.2	22.1	±21.1	0.78
Ventilator-free days in 1 month	11.6	±9.0	12.2	±9.4	0.84
Total ventilator days	47.3	±28.8	49.2	±36.0	0.85
Total hospital days	77.0	±40.0	71.7	±39.1	0.92

Notes: Data were presented as either n (%) or mean ± SD.

Abbreviations: NAVA, neurally adjusted ventilatory assist; RCC, respiratory care center.

Figure 3 Asynchrony index of the all patients.

Notes: Filled circles indicate individual asynchrony index of each patient. Fourteen patients had AI >10% in the control group, but no patients had AI in NAVA mode.

Abbreviations: NAVA, neurally adjusted ventilatory assist; AI, asynchrony index.

Figure 4 Accumulated asynchrony numbers of the NAVA and control group.

Abbreviation: NAVA, neurally adjusted ventilatory assist.