Continuous prolonged prone positioning in COVID-19-related ARDS: a multicenter cohort study from Chile

Cornejo, Rodrigo A.; Montoya, Jorge; Gajardo, Abraham I. J.; Graf, Jerónimo; Alegría, Leyla; Baghetti, Romyna; Irarrázaval, Anita; Santis, César; Pavez, Nicolás; Leighton, Sofía; Tomicic, Vinko; Morales, Daniel; Ruiz, Carolina; Navarrete, Pablo; Vargas, Patricio; Gálvez, Roberto; Espinosa, Victoria; Lazo, Marioli; Pérez-Araos, Rodrigo A.; Garay, Osvaldo; Sepúlveda, Patrick; Martinez, Edgardo; Bruhn, Alejandro

doi:10.1186/s13613-022-01082-w

Annals of Intensive Care

Table 2 Respiratory parameters before and after starting the first prone session

From: Continuous prolonged prone positioning in COVID-19-related ARDS: a multicenter cohort study from Chile

	Total (n = 417)	Group A (n = 191)	Group B (n = 128)	Group C (n = 98)	p value
Respiratory rate, breaths per minute, median (IQR)
Before starting prone positioning	26 (23–30)	25 (22–28)	26 (24–30)	28 (24–30)	< 0.001
At day 1 in prone positioning	26 (24–30)	26 (24–28)	27 (24–30)	28 (26–30)	< 0.001
Δ Respiratory rate [PP day 1–before PP]	0 (0–2)	0 (0–2)	0 (0–2)	0 (0–4)	0.260
Tidal volume, mL/kg IBW, median (IQR)
Before starting prone positioning	6.2 (5.7–6.8)	6.3 (5.7–6.9)	6.1 (5.7–6.9)	6.1 (5.7–6.8)	0.530
At day 1 in prone positioning	6.2 (5.7–6.8)	6.2 (5.7–6.8)	6.2 (5.7–6.9)	6.2 (5.7–6.8)	0.999
Δ VT [PP day 1–before PP]	0.0 (− 0.2, 0.2)	0.0 (− 0.2, 0.1)	0.0 (− 0.2, 0.2)	0.0 (− 0.2, 0.3)	0.235
Plateau pressure, cm H₂O, median (IQR)
Before starting prone positioning	23 (21–26)	23 (21–25)	24 (21–28)	25 (21–27)	0.003
At day 1 in prone positioning	22 (21–25)	22 (20–24)	23 (21–26)	23 (21–25)	0.002
Δ Plateau pressure [PP day 1–before PP]	− 1 (−3 to 1)	− 1 (− 3 to 1)	− 1 (− 3 to 1)	− 1 (− 3 to 2)	0.685
Driving pressure, cm H₂O, median (IQR)
Before starting prone positioning	12 (10–15)	12 (10–14)	13 (11–15)	13 (11–16)	0.005
At day 1 in prone positioning	12 (10–14)	11 (10–13)	12 (10–15)	13 (11–14)	< 0.001
Δ Driving pressure [PP day 1–before PP]	− 1 (− 2 to 1)	− 1 (− 2 to 1)	0 (− 2 to 1)	− 1 (− 2 to 1)	0.976
PEEP, cm H₂O, median (IQR)
Before starting prone positioning	10 (8–12)	10 (8–12)	10 (9–12)	10 (8–12)	0.309
At day 1 in prone positioning	10 (8–12)	10 (8–12)	10 (8–12)	10 (8–12)	0.686
Δ PEEP [PP day 1–before PP]	0 (− 2 to 0)	0 (−1 to 0)	0 (−2 to 0)	0 (−1 to 0)	0.385
Static compliance, mL/cm H₂O, median (IQR)
Before starting prone positioning	31 (25–38)	32 (27–38)	30 (25–38)	30 (23–36)	0.133
At day 1 in prone positioning	32 (27–39)	33 (28–40)	32 (26–39)	30 (27–36)	0.007
Δ Static compliance [PP day 1–before PP]	2 (− 3 to 5)	2 (− 2 to 6)	1 (− 3 to 4)	1 (− 4 to 4)	0.070
PaO₂, mm Hg, median (IQR)
Before starting prone positioning	75 (64–87)	76 (66–87)	71 (63–83)	77 (62–89)	0.168
At day 1 in prone positioning	84 (72–102)	89 (75–109)	82 (71–96)	80 (69–97)	0.013
Δ PaO₂ [PP day 1–before PP]	10 (− 3 to 28)	12 (− 4 to 35)	8 (− 3 to 26)	9 (− 4 to 21)	0.218
FiO₂, median (IQR)
Before starting prone positioning	0.65 (0.50–0.90)	0.60 (0.50–0.80)	0.65 (0.50–1.0)	0.75 (0.60–1.0)	0.002
At day 1 in prone positioning	0.50 (0.40–0.60)	0.40 (0.35–0.50)	0.50 (0.40–0.60)	0.55 (0.50–0.70)	< 0.001
Δ FiO₂ [PP day 1–before PP]	− 0.15 (− 0.3 to − 0.05)	− 0.20 (− 0.35 to − 0.05)	− 0.15 (− 0.35 to 0.0)	− 0.20 (− 0.30 to 0.0)	0.293
PaO₂:FiO₂ ratio, median (IQR)
Before starting prone positioning	119 (85–154)	127 (98–162)	114 (86–150)	106 (81–140)	0.003
At day 1 in prone positioning	184 (139–240)	224 (174–270)	176 (133–214)	145 (117–183)	< 0.001
Δ PaO₂:FiO₂ ratio [PP day 1–before PP]	61 (23–115)	88 (34–151)	53 (19–89)	39 (18–71)	< 0.001
PaCO₂, mm Hg, median (IQR)
Before starting prone positioning	45 (39–53)	43 (38–48)	47 (40–56)	47 (40–56)	< 0.001
At day 1 in prone positioning	45 (40–51)	43 (39–50)	46 (41–54)	47 (43–53)	< 0.001
Δ PaCO₂ [PP day 1–before PP]	0 (− 6 to 6)	0 (− 5 to 6)	− 1 (− 8 to 6)	− 0 (− 6 to 4)	0.408
pH, median (IQR)
Before starting prone positioning	7.34 (7.27–7.40)	7.36 (7.30–7.41)	7.34 (7.26–7.40)	7.31 (7.26–7.36)	< 0.001
At day 1 in prone positioning	7.35 (7.29–7.40)	7.37 (7.30–7.41)	7.35 (7.29–7.40)	7.32 (7.28–7.36)	0.004
Δ pH [PP day 1–before PP]	0.0 (− 0.0, 0.1)	0.0 (− 0.0, 0.1)	0.0 (− 0.0, 0.1)	0.0 (− 0.0, 0.1)	0.196
Ventilatory ratio, median (IQR)
Before starting prone positioning	1.9 (1.6–2.4)	1.8 (1.5–2.2)	2.1 (1.6–2.7)	2.1 (1.8–2.6)	< 0.001
At day 1 in prone positioning	2.0 (1.6–2.5)	1.8 (1.5–2.3)	2.1 (1.7–2.6)	2.2 (1.9–2.8)	< 0.001
Δ Ventilatory ratio [PP day 1–before PP]	0.0 (− 0.2 to 0.3)	0.0 (− 0.2 to 0.3)	− 0.0 (− 0.3 to 0.3)	0.0 (− 0.1 to 0.3)	0.441

Group A patients remained 2–3 days in prone position during their first session. Group B patients remained 4–5 days in prone position during their first session. Group C patients remained more than 5 days in prone position during their first session. The data reported as before starting prone positioning (upper half of the table) correspond to the last data registered in the clinical files before turning the patient to prone position for the first time, while the data reported as after starting prone positioning (lower half of the table) correspond to the first data registered in the clinical files collected while the patient was in prone position
PaO2 partial pressure of arterial oxygen, FiO2 Inspired oxygen fraction, PaO2:FiO2 ratio: ratio of partial pressure of arterial oxygen to inspired oxygen fraction, PaCO2 partial pressure of arterial carbon dioxide, PEEP Positive end-expiratory pressure, Static compliance: Static respiratory system compliance, Ventilatory ratio is a unit less index calculated as (minute ventilation in ml/min x PaCO2)/(Ideal body weight × 100 × 37.5)

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