Table 2 Baseline characteristics of the patients in two groups of PEEP settings guided transpulmonary pressure

Variable	Total
(n=46)	Constant PEEP group
(n=19)	Adjusted PEEP group
(n=27)	p-value
Characteristics of patients
Age (year)	49.8±15.5	50.6±18.7	49.1±13.2	0.517
Male, n (%)	32 (69.6)	14 (73.7)	18 (66.7)	0.854
BMI (kg/m2)	24.2 [21.4–27.4]	22.1 [19.5–23.7]	26.2 [24.2–29.3]	<0.001*
Actual body weight (kg)	67 [55.0–75.0]	55 [51.5–62.5]	70 [64.5–80]	0.001*
SOFA score	10.0 [8.0–13.8]	11 [8–14]	10 [8–12]	0.522
APACHE II score	19.0 [16.3–26.8]	21 [17.5–25.5]	19 [16–27.5]	0.591
CCI score	2 [1–3]	2 [1–3]	1 [1–3]	0.782
VIS score	5.6 [0–13.5]	5.3 [0–16.4]	5.9 [0–12.8]	0.954
Lactate (mmol/L)	2.2 [1.5–3.1]	2.35 [1.84–3]	1.9 [1.56–3.26]	0.321
Heart rate (beat/min)	114 [101–128]	120 [104–131]	110 [101–127]	0.455
Mean arterial pressure (mmHg)	86.7 [76.7–93.8]	86.7 [79.0–91.0]	86.7 [75.5–98.2]	0.606
ARDS classification, n (%)				1
Moderate (PaO2/FiO2<200)	35 (76.1)	15 (78.9)	20 (74.1)
Severe (PaO2/FiO2<100)	11 (23.9)	4 (21.1)	7 (25.9)
Air blood gas
pH	7.4 [7.35–7.45]	7.4 [7.34–7.44]	7.4 [7.35–7.47]	0.655
PaCO2 (mmHg)	39.9 [35.2–43.3]	42.1 [36.4–44.3]	39 [34.4–42]	0.174
PaO2 (mmHg)	81.4 [67.2–97.4]	81.4 [70.1–104]	77 [65.6–93.2]	0.468
Respiratory parameters
Tidal volume (mL)	400 [380–400]	400 [380–400]	400 [390–410]	0.377
Respiratory rate (rate/min)	22.0 [20.0–25.0]	24 [20–26]	22 [20–24.5]	0.417
PEEP (cm H2O)	10 [8–10]	10 [10–12]	8 [8–10]	0.002*
FiO2 (%)	60 [52–80]	60 [57–78]	60 [50–80]	0.867
Airway driving pressure (cm H2O)	17.0 [14.0–20.0]	15 [13–16.8]	19 [16.2–20.9]	0.001*
Plateau pressure (cm H2O)	27.0 [24.0–29.0]	25 [22.5–27]	28 [26–29]	0.065
Crs (mL/cm H2O)	23.8 [19.7–27.7]	26.5 [24.3–29.2]	20.6 [18.3–24.5]	0.001*
Adjusting PEEP	2 [0–2]	0 [0–0]	2 [2–4]	<0.001*
Outcomes
Ventilator days (days)	12 [8–20]	12.0 [9.5–17.5]	12.0 [8.0–22.0]	0.729
Length of hospital stay (days)	19.0 [14.0–25.8]	16.0 [14.0–21.0]	21.0 [14.0–27.0]	0.241
In-hospital mortality, n (%)	18 (39.1)	8 (42.1)	10 (37.0)	0.728

Data are presented as n (%) for categorical variables and the median (interquartile range) for nonparametric variables.
APACHE-II, Acute Physiologic Assessment and Chronic Health Evaluation-II; BMI, body mass index; CCI, Charlson Comorbidity Index; Crs, compliance respiratory system; SOFA, Sequential Organ Failure Assessment; FiO2, fraction of inspired oxygen; PaO2, partial pressure of arterial oxygen; PEEP, positive end-expiratory pressure; VIS, Vasopressor Index Score.