Individual response in patient’s effort and driving pressure to variations in assistance during pressure support ventilation

Annals of Intensive Care

Table 1 Respiratory variables at the different pressure supports tested

	−6 cmH₂O	−3 cmH₂O	Clinical PS	+ 3 cmH₂O	+ 6 cmH₂O	P-value
PS, cmH₂O	1.8 ± 2.1	4.8 ± 2.1	7.8 ± 2.1	10.8 ± 2.1	13.8 ± 2.1	< 0.001
PEEP, cmH₂O	7.8 ± 2.6	7.8 ± 2.6	7.8 ± 2.6	7.8 ± 2.6	7.8 ± 2.6	N/A
Vt, L	0.42 ± 0.11	0.45 ± 0.10	0.46 ± 0.10	0.53 ± 0.13	0.59 ± 0.17	< 0.001
Vt, mL/Kg	6.9 ± 1.5	7.4 ± 1.5	7.8 ± 1.4	8.9 ± 2.0	10.0 ± 2.6	< 0.001
Vt coefficient of variation	0.15 ± 0.08	0.14 ± 0.09	0.12 ± 0.05	0.09 ± 0.05	0.07 ± 0.04	< 0.001
MV, L/min	8.6 ± 1.8	8.5 ± 1.5	8.6 ± 1.4	8.3 ± 1.4	8.9 ± 1.6	0.663
RR, breaths/min	22 ± 4	20 ± 4	19 ± 5	17 ± 4	15 ± 5	< 0.001
RSBI, breaths/min/L	52 ± 19	44 ± 17	43 ± 23	33 ± 13	27 ± 16	< 0.001
Ppeak, cmH₂O	9.7 ± 3.8	12.7 ± 3.8	15.7 ± 3.8	18.7 ± 3.8	21.7 ± 3.8	< 0.001
MAP, cmH₂O	8.2 ± 2.8	8.9 ± 2.5	10.3 ± 3.1	10.5 ± 2.5	11.3 ± 2.7	< 0.001
Pplat, cmH₂O	16.7 ± 2.9	17.4 ± 3.5	18.1 ± 2.6	19.1 ± 2.8	20.5 ± 3.3	< 0.001
∆P, cmH₂O	8.6 ± 2.3	9.5 ± 2.4	10.1 ± 1.8	11.2 ± 1.9	12.5 ± 2.3	< 0.001
Crs, mL/cmH₂O	51 ± 13	49 ± 13	47 ± 13	48 ± 12	48 ± 13	0.119
PMI, cmH₂O	6.4 ± 3.2	4.7 ± 3.2	2.3 ± 2.6	0.4 ± 2.2	−1.2 ± 2.3	< 0.001
Pocc, cmH₂O	−14.8 ± 6.4	−10.7 ± 6.4	−7.9 ± 4.5	−5.5 ± 4.3	−4.8 ± 3.5	< 0.001
P0.1, cmH₂O	−2.5 ± 1.2	−2.0 ± 1.3	−1.4 ± 0.8	−1.0 ± 0.7	−0.8 ± 0.8	< 0.001
EADi,surf, %clin	191 ± 78	134 ± 61	100 ± 0	77 ± 31	70 ± 27	< 0.001
Intercost,surf, %clin	150 ± 51	114 ± 29	100 ± 0	70 ± 26	74 ± 38	< 0.001

Data are presented as mean ± SD. P-values shown correspond to one-way ANOVA for repeated measurements significance level. Surface electromyography of diaphragm (EADi,surf) and intercostal muscles (Intercost,surf) is expressed as percentage of the signal at clinical PS (%clin). PS pressure support, PEEP positive end expiratory pressure, Vt tidal volume, MV minute ventilation, RR respiratory rate, RSBI, rapid shallow breathing index, Ppeak peak airway pressure, MAP mean airway pressure, Pplat, plateau pressure, ∆P driving pressure, Crs respiratory system compliance, PMI pressure-muscle-index