Critical Care Research and Practice

Research Article

Noninvasive Mechanical Ventilation with Average Volume-Assured Pressure Support versus BiPAP S/T in De Novo Hypoxemic Respiratory Failure

Table 2

Comparison of characteristics between the groups.


Variables	BIPAP S/T (n = 29)	BIPAP S/T-AVAPS (n = 29)	value

Age (years), mean (SD)	71.8 ± 18.4	66.9 ± 20.2	0.33
Sex, N (%)	Men 20 (69) and women 9 (31)	Men 19 (65.5) and women 10 (34.5)	0.78
Weight kg (PBW), mean (SD)	65 ± 9.6	66.1 ± 10.5	0.67
APACHE II score, mean (SD)	18.4 ± 3.1	19 ± 2.9	0.44
Risk factors for ARDS
Community pneumonia, N (%)	27 (93.1)	24 (82.9)	0.39
Postoperative acute abdomen, N (%)	—	1 (3.4) (%)
Acute pancreatitis, N (%)	2 (6.9)	4 (13.8)
Radiographic quadrants affected, N (%)	1.5 ± 0.6	1.5 ± 0.6	1
SBP, mmHg, mean (SD)	75.2 ± 8.8	74.3 ± 8.9	0.7
DBP, mmHg, mean (SD)	125.5 ± 18.5	121.9 ± 19.8	0.47
HR, beat/min, mean (SD)	97.8 ± 14	97.5 ± 13.4	0.93
RR, breath/min, mean (SD)	26.8 ± 7.9	26.4 ± 5.2	0.8
ABGs
PaO₂/FiO₂ (initial), mean (SD)	185.5 ± 30.6	181.6 ± 32.8	0.64
pH, mean (SD)	7.42 ± 0.05	7.43 ± 0.06	0.49
PCO₂, mmHg, mean (SD)	33.1 ± 6.1	32 ± 5.4	0.47
pO₂, mmHg, mean (SD)	75.4 ± 8.7	75.1 ± 10.6	0.9
HCO₃, mmol/L, mean (SD)	22.5 ± 4	22.5 ± 4.3	1
EB, mmol/L, mean (SD)	−2.5 ± 4.7	−1.1 ± 7.8	0.40
SAT 02, (%), mean (SD)	0.93 ± 0.03	0.93 ± 0.03	1
FiO₂. (%), mean (SD)	0.41 ± 0.03	0.41 ± 0.03	1
Ventilatory parameters
IPAP, cmH₂O, mean (SD)	12.8 ± 1.4	16.2 ± 2.8	<0.0001
EPAP, cmH₂O, mean (SD)	6 ± 0.5	6 ± 0.2	1
RAMP, sec, mean (SD)	3.1 ± 0.4	3.2 ± 0.4	0.3452
IT, sec, mean (SD)	0.94 ± 0.03	0.94 ± 0.03	1
Leakage, cmH₂O, mean (SD)	17.2 ± 8.7	16.7 ± 9.2	0.83
Vmin, L/min, mean (SD)	13.6 ± 2.5	12.8 ± 2.4	0.21
Vtexh, ml, mean (SD)	456 ± 70.1	453.9 ± 76.4	0.91
Vt/ml/kg (PBW), mean (SD)	7 ± 1	6.9 ± 0.9	0.69

(statistically significant). APACHE II, assessment score of acute physiology and chronic health evaluation; SBP: systolic blood pressure; DBP: diastolic blood pressure; HR: heart rate; RR: respiratory rate; PaO₂/FiO₂: ratio of partial arterial oxygen pressure and inspired fraction of oxygen; PCO₂: partial pressure of carbon dioxide; HCO₃: bicarbonates; EB: excess base, SAT 02: arterial oxygen saturation; FiO₂: inspired fraction of oxygen; IPAP: inspiratory positive airway pressure; EPAP: expiratory positive airway pressure; RAMP: time to change from the expiratory pressure setting to the inspiratory pressure setting; IT: inspiratory time; Vmin: volume per minute; Vtexh: exhaled tidal volume; Vt: tidal volume.