Twenty-four-hour mechanical power variation rate is associated with mortality among critically ill patients with acute respiratory failure: a retrospective cohort study

Table 4 Baseline and 24-h respiratory parameters

Variables	MP variation rate ≤ 0% (MP-worsened, n = 173)	MP variation rate > 0% (MP-improved, n = 429)	p
Baseline tidal volume, mL/kg PBW	6.7 (5.9, 7.4)	7.1 (6.4, 7.9)	< 0.001
24-h tidal volume, mL/kg PBW	6.9 (6.2, 7.9)*	6.9 (5.9, 7.8)*	0.208
Baseline minute ventilation, L/min	8.4 (7.6, 9.4)	8.6 (7.7, 9.9)	0.115
24-h minute ventilation, L/min	9.0 (8.1, 10.2)*	7.5 (6.5, 8.5)*	< 0.001
Baseline PEEP, cmH₂O	8 (6, 9)	7 (6, 8)	0.353
24-h PEEP, cmH₂O	8 (7, 10)*	6 (5, 8)*	< 0.001
Baseline Cdyn, mL/cmH₂O	31.7 (24.7, 37.5)	31.0 (25.3, 39.3)	0.63
24-h Cdyn, mL/cmH₂O	30.9 (22.4, 39.3)	35.3 (27.6, 44.9)*	< 0.001
Baseline arterial pH	7.36 (7.29, 7.42)	7.39 (7.32, 7.45)	0.004
24-h arterial pH	7.43 (7.38, 7.47)*	7.44 (7.41, 7.48)*	0.024
Baseline PaCO2, mmHg	42.4 (37.6, 51.6)	38.9 (33.4, 44.3)	< 0.001
24-h PaCO2, mmHg	41.0 (37.7, 46.2)*	40.7 (37.0, 44.3)*	0.073
Baseline PaO₂/FiO₂ ratio, mmHg	123.6 (87.9, 167.0)	134.7 (98.0, 193.3)	0.006
24-h PaO₂/FiO₂ ratio, mmHg	212.8 (159.1, 280)*	245.0 (184.9, 294.3)*	0.003
Baseline FiO₂, %	49 (39, 59)	45 (38, 55)	0.022
24-h FiO₂, %	42 (36, 52)*	38 (32, 44)*	< 0.001
Baseline PaO₂, mmHg	60.1 (49.0, 76.6)	64.2 (50.6, 80.0)	0.061
24-h PaO₂, mmHg	86.9 (72.7, 104.0)*	86.5 (74.7, 104.1)*	0.811
Baseline ventilatory ratio	1.50 (1.30, 1.78)	1.42 (1.21, 1.68)	0.018
24-h ventilatory ratio	1.51 (1.33, 1.78)	1.25 (1.12, 1.41)*	< 0.001

IQR, interquartile range; PBW, predicted body weight; PEEP, positive end-expiratory pressure; Cdyn, dynamic compliance of respiratory system; PaO₂, partial pressure of arterial oxygen; FiO₂, fraction of inspired oxygen
^*p < 0.05 comparing same parameters at baseline and 24-h by Wilcoxon signed-rank test

ISSN: 1471-2466