Predicting prolonged postoperative ileus in gastric cancer patients based on bowel sounds using intelligent auscultation and machine learning

Table 3 Association of prolonged postoperative ileus with background and operative variables in bivariate analysis and in multivariable models

Variable	PPOI number (%)	P value	Multivariable OR (95CI)		P value
Age					0.009
≥ 70	11/25 (44)	< 0.001	5.779
< 70	12/59 (56)		(1.620-23.84)
Gender
Male	15/59 (25.4)	0.386
Female	8/25 (32.0)
BMI
< 18.5	4/10 (40.0)	-
≥ 18.8 < 25	16/58 (27.5)	0.181
≥ 25	3/16 (18.8)	0.094
Smoking		0.267
Yes	7/37 (18.9)
No	16/47 (34.0)
Drinking		0.235
Yes	6/17 (35.3)
No	17/67 (25.3)
Hypertension		0.972
Yes	7/28 (25.0)
No	16/56 (28.6)
Diabetes		0.182
Yes	1/9 (11.1)
No	22/75 (29.3)
Previous abdominal surgery		0.36
Yes	8/19 (42.1)
No	15/65 (23.1)
Anemia		0.702
Yes	8/31 (25.8)
No	15/53 (28.3)
Hypoproteinemia		< 0.001	15.0 (3.44-87.19)		< 0.001
Yes	7/28 (25.0)
No	16/56 (28.6)
Preoperative potassium		0.634
Normal	21/76 (27.6)
Abnormal	2/8 (25.0)
Emergency surgery		0.819
Yes	0/1 (0.0)
No	23/83 (27.1)
Tumor size (cm)
< 5	12/52 (23.1)	-
≥ 5 < 10	8/27 (29.6)	0.535
≥ 10	3/5 (60.0)	0.449
Tumor site
Cardiac	3/13 (23.1)	-
Body	14/46 (30.4)	1
Antrum	6/25 (24.0)	0.767
Stage cTNM
0	0/11 (0.0)	-	-
I	5/13 (38.5)	0.091	19.64 (1.57-646.93)		0.042
II	6/25 (24.0)	0.096	5.46 (0.49-149.62)		0.216
III	8/28 (28.6)	0.073	9.71 (0.99-256.35)		0.089
IV	4/7 (57.1)	0.026	98.8 (4.55-4617.35)		0.006
RTBS		0.012	0.15 (0.03-0.59)		0.001
≥ 15	7/16 (43.8)
< 15	16/68 (23.5)
NBS (cpm)		0.001	0.077 (0.01-0.33)		0.001
≥ 2.436	18/64 (28.1)
< 2.436	5/20 (25.0)
BSVA (dB)		0.2
≥ 44.793	5/23 (21.7)
< 44.793	18/61 (29.5)
FBS (Hz)		0.007	8.81 (2.35-10.91)		0.002
≥ 461.560	12/59 (20.3)
< 461.560	11/25 (44.0)

Age, cTNM stage, preoperative hypoproteinemia, and specific bowel sound-related indices (recovery time of bowel sounds, number of bowel sounds, frequency of bowel sounds) were independent risk factors influencing the occurrence of PPOI in patients with gastric cancer. NBS: Number of bowel sounds; BSVA: Bowel sound vibration amplitude; FBS: Frequency of bowel sounds; RTBS: Recovery time of bowel sounds; BMI: Body mass index; PPOI: Prolonged postoperative ileus.