Table 1 Characteristics of enrolled patients

Age, mean (SD), y

57.57 (15.46)

60.64 (16.53)

54.41 (13.93)

0.030

Male, n (%)

78.00 (66.67)

38.00 (67.86)

40.00 (65.57)

0.794

BMI, mean (SD)

22.47 (4.24)

22.43 (3.67)

22.52 (4.77)

0.911

ARISCAT score, mean (SD)

38.39(16.74)

47.93 (16.04)

30.07 (12.11)

< 0.001

ASA class, n (%)

< 0.001

 Grade 2

55.00 (47.01)

14.00 (25)

41.00 (67.21)

 Grade 3

56.00 (47.86)

40.00 (71.43)

16.00 (26.23)

 Grade 4

6.00 (5.13)

2.00 (3.57)

4.00 (6.56)

 APACHE II score, mean (SD)

13.29 (7.39)

14.75 (7.87)

11.95 (6.77)

0.041

Comorbidity, n (%)

 Cardiovascular disease

20.00 (17.09)

15.00 (26.79)

5.00 (8.20)

0.008

 Diabetes mellitus

9.00 (7.69)

4.00 (7.14)

5.00 (8.20)

1.000

 COPD

4.00 (3.42)

3.00 (5.36)

1.00(1.64)

0.551

 Hyperlipoidemia

5.00 (4.27)

5.00 (8.93)

0.00 (0.00)

0.054

 Hypertension

17.00 (14.53)

11.00 (19.64)

6.00 (9.84)

0.133

 Active cancer

49.00 (41.88)

21.00 (37.50)

28.00 (45.90)

0.357

 Chronic renal disease

38.00 (32.48)

22.00 (39.29)

16.00 (26.23)

0.132

 Chronic liver disease

48.00 (41.03)

22.00 (39.29)

26.00 (42.62)

0.714

 Chronic bronchitis

4.00 (3.42)

4.00 (7.14)

0.00 (0.00)

0.106

Type of surgery, n (%)

 Emergency surgery

42.00 (35.90)

31.00 (55.36)

11.00 (18.03)

< 0.001

Planned surgical procedure, n (%)

0.318

 Resection of colon, rectum, or small bowel

19.00 (16.24)

12.00 (21.43)

7.00 (11.48)

 Resection of liver, pancreas, or gall bladder

69.00 (58.98)

32.00 (57.15)

37.00 (60.66)

 Resection of stomach

5.00 (4.27)

3.00 (5.36)

2.00 (3.28)

 Other intraperitoneal surgery

24 (20.51)

9(16.07)

15(24.59)

Incision type, n (%)

0.803

 Midline laparotomy

61.00 (52.14)

31.00 (55.36)

30.00 (49.18)

 Bilateral or unilateral subcostal

23.00 (19.66)

12.00 (21.43)

11.00 (18.03)

 Transverse abdominal

1.00 (0.85)

0.00 (0.00)

1.00 (1.64)

 Laparoscopic or lower abdominal

13.00 (11.10)

5.00 (9.00)

8.00 (13.10)

 Other

19.00 (16.24)

8.00 (14.29)

11.00 (18.03)

 Length of procedure, mean (SD), mins

199.84 (189.01)

184.89 (184.10)

213.18 (196.95)

0.425

Diaphragm echodensity, median (IQR)

 ED50

30.00 (22.00–38.00)

35.00 (22.00–44.00)

26.00 (21.00–35.00)

< 0.001

 EDmean

35.33 (26.82–43.63)

39.32 (29.88–48.37)

33.98 (26.14–41.37)

< 0.001

 ED85

58.00 (46.00–72.00)

64.00 (49.00–76.00)

55.00 (44.00–63.00)

< 0.001

 Diaphragm mobility, mean (SD), cm

1.10 (0.44)

1.12 (0.41)

1.08 (0. 47)

0.696

 Diaphragm thickness, mean (SD), cm

0.23 (0.07)

0.23 (0.07)

0.22 (0.06)

0.354

 Length of ICU stay, mean (SD), day

6.48 (6.21)

8.11 (7.39)

4.98 (4.51)

0.008

 Length of hospital stay, mean (SD), day

17.37 (15.49)

20.21 (17.81)

14.75 (12.76)

0.061

 VFD-28, mean (SD), day

25.35 (3.78)

24.55 (4.17)

26.05 (3.32)

0.035

 Mortality, n (%)

6.00 (5.13)

5.00 (8.93)

1.00 (1.64)

0.103

 Reintubation, n (%)

7.00 (5.98)

6.00 (10.71)

1.00 (1.64)

0.093

Ventilatory support after extubation, n (%)

0.001

 COT

68.00 (58.12)

26.00 (46.43)

42.00 (68.85)

 HFNC

14.00 (11.86)

4.00 (7.14)

10.00 (16.13)

 NIPPV

35.00 (29.66)

26.00 (46.43)

9.00 (14.52)