Application value of machine learning models in predicting intraoperative hypothermia in laparoscopic surgery for polytrauma patients

Table 1 Comparison of clinical data

Parameter	Training (n = 154)	Validation (n = 66)	Statistical value	P value
Sex			χ2 = 0.383	0.536
Male	84 (54.55)	33 (50.00)
Female	70 (45.45)	33 (50.00)
Age in years	54.34 ± 11.58	55.87 ± 10.79	t = 0.916	0.361
Basal body temperature in °C	34.05 ± 0.22	34.01 ± 0.29	t = 1.119	0.264
BMI in kg/m2	23.27 ± 2.82	23.65 ± 2.75	t = 0.923	0.357
Diabetes			χ2 = 2.013	0.156
Yes	19 (12.34)	13 (19.70)
No	135 (87.66)	53 (80.30)
Hypertension			χ2 = 2.685	0.101
Yes	31 (20.13)	20 (30.30)
No	123 (79.87)	46 (69.70)
Smoking			χ2 = 2.013	0.156
Yes	19 (12.34)	13 (19.70)
No	135 (87.66)	53 (80.30)
Drinking			χ2 = 2.127	0.145
Yes	15 (9.74)	11 (16.67)
No	139 (90.26)	55 (83.33)
Operating room temperature in °C	21.65 ± 4.16	21.52 ± 4.12	t = 0.213	0.832
ASA			χ2 = 5.034	0.169
I	16 (10.39)	10 (15.15)
II	116 (75.32)	41 (62.12)
III	21 (13.64)	13 (19.70)
IV	1 (0.65)	2 (3.03)
Mode of anesthesia			χ2 = 0.542	0.462
General anesthesia	71 (46.10)	34 (51.52)
General anesthesia joint board anesthesia	83 (53.90)	32 (48.48)
Duration of anesthesia in min	150.48 ± 76.21	139.39 ± 75.97	t = 0.990	0.323
Operation duration in min	127.61 ± 78.16	124.65 ± 75.77	t = 0.260	0.795
Intraoperative fluid infusion in mL	1067.84 ± 616.12	1073.92 ± 610.11	t = 0.067	0.946
Infusion of crystal solution in mL	1050.13 ± 567.08	1041.37 ± 600.42	t = 0.103	0.918
Infusion of colloidal solution in mL	92.68 ± 15.22	91.15 ± 15.14	t = 0.684	0.495
Pneumoperitoneum flow in L/min	261.22 ± 16.13	258.09 ± 15.96	t = 1.323	0.187
Intraoperative blood loss in mL	98.27 ± 35.82	94.18 ± 35.61	t = 0.777	0.438
Hemoglobin in g/L	115.65 ± 18.15	113.74 ± 17.05	t = 0.728	0.467
Platelet as × 109/L	180.88 ± 56.32	176.87 ± 56.76	t = 0.483	0.630
Glu in mmol/L	4.15 ± 0.87	4.25 ± 0.86	t = 0.784	0.434
ALT in U/L	25.58 ± 10.19	27.02 ± 10.12	t = 0.962	0.337
AST in U/L	20.27 ± 8.82	19.18 ± 8.75	t = 0.842	0.401

Data are mean ± standard deviation or n (%). ALT: Alanine aminotransferase; ASA: American society of anesthesiologists; AST: Aspartate aminotransferase; BMI: Body mass index; Glu: Glucose.

Table 2 Comparison of clinical data of patients with and without hypothermia in the training set group

Item	Hypothermia, n = 53	Non-hypothermia, n = 101	Statistical value	P value
Sex			χ2 = 9.210	0.002
Male	20 (37.74)	64 (63.37)
Female	33 (62.26)	37 (36.63)
Age in years	61.11 ± 12.15	57.23 ± 8.71	t = 2.282	0.024
Basal body temperature in °C	36.15 ± 0.28	36.74 ± 0.28	t = 12.423	< 0.001
BMI in kg/m2	23.73 ± 2.71	23.75 ± 3.25	t = 0.038	0.970
Diabetes			χ2 = 1.715	0.190
Yes	4 (7.55)	15 (14.85)
No	49 (92.45)	86 (85.15)
Hypertension			χ2 = 0.498	0.480
Yes	9 (16.98)	22 (21.78)
No	44 (83.02)	79 (78.22)
Smoking			χ2 = 0.077	0.781
Yes	6 (11.32)	13 (12.87)
No	47 (88.68)	88 (87.13)
Drinking			χ2 = 0.442	0.506
Yes	4 (7.55)	11 (10.89)
No	49 (92.45)	90 (89.11)
Operating room temperature in °C	21.12 ± 4.05	22.84 ± 5.02	t = 2.153	0.033
ASA			χ2 = 4.325	0.228
I	3 (5.66)	13 (12.87)
II	43 (81.13)	73 (72.28)
III	6 (11.32)	15 (14.85)
IV	1 (1.89)	0
Mode of anesthesia			χ2 = 0.238	0.625
General anesthesia	23 (43.40)	48 (47.52)
General anesthesia joint board anesthesia	30 (56.60)	53 (52.48)
Duration of anesthesia in min	162.52 ± 75.16	118.63 ± 58.35	t = 4.006	< 0.001
Operation duration in min	141.27 ± 75.11	99.21 ± 56.22	t = 3.916	< 0.001
Intraoperative fluid infusion in mL	1157.12 ± 615.51	793.15 ± 422.17	t = 4.319	< 0.001
Infusion of crystal solution in mL	1046.01 ± 560.12	769.34 ± 389.25	t = 3.585	0.001
Infusion of colloidal solution in mL	103.41 ± 15.06	27.79 ± 7.15	t = 42.274	< 0.001
Pneumoperitoneum flow in L/min	270.51 ± 17.21	187.29 ± 11.19	t = 36.200	< 0.001
Intraoperative blood loss in mL	118.33 ± 33.95	112.79 ± 35.31	t = 0.937	0.350
Hemoglobin in g/L	134.98 ± 20.85	136.58 ± 19.69	t = 0.469	0.639
Platelet as × 109/	208.76 ± 62.16	211.41 ± 59.52	t = 0.259	0.796
Glu in mmol/L	5.14 ± 0.95	5.21 ± 1.06	t = 0.403	0.687
ALT in U/L	26.89 ± 10.41	25.79 ± 10.68	t = 0.612	0.541
AST in U/L	21.27 ± 9.12	20.39 ± 8.97	t = 0.575	0.566

Data are mean ± standard deviation or n (%). ALT: Alanine aminotransferase; ASA: American society of anesthesiologists; AST: Aspartate aminotransferase; BMI: Body mass index; Glu: Glucose.

Table 3 Variable assignment

Variable	Factor	Assignment
Y	Hypothermia	1 = hypothermia; 0 = non-hypothermia
X1	Age	Continuous variable, original value input
X2	Basal body temperature	Continuous variable, original value input
X3	Operating room temperature	Continuous variable, original value input
X4	Duration of anesthesia	Continuous variable, original value input
X5	Operation duration	Continuous variable, original value input
X6	Intraoperative fluid infusion	Continuous variable, original value input
X7	Infusion of crystal solution	Continuous variable, original value input
X8	Infusion of colloidal solution	Continuous variable, original value input
X9	Pneumoperitoneum flow	Continuous variable, original value input
X10	Sex	0 = Male; 1 = Female

Table 4 Multivariate logistic regression analysis

Risk factor	β	SE	Wald χ2	P value	OR	95%CI
Age	0.056	0.017	11.434	0.001	1.058	1.024-1.093
Basal body temperature	−1.211	0.365	11.157	0.001	0.286	0.231-0.976
Operating room temperature	−0.066	0.041	2.688	0.101	0.936	0.864-1.013
Duration of anesthesia	−0.008	0.003	8.458	0.004	0.992	0.986-0.997
Operation duration	0.011	0.003	12.787	< 0.001	1.011	1.005-1.018

95%CI: 95% Confidence interval; OR: Odds ratio; SE: Standard error.

Table 5 Nomogram model for predicting the occurrence of hypothermia during laparoscopic surgery

Index	AUC	SEN, %	SPE, %	95%CI	P value
Training	0.850	94.69	91.47	0.909-0.962	< 0.001
Validation	0.829	95.38	90.53	0.850-0.988	< 0.001

95%CI: 95% Confidence interval; AUC: Area under the curve; SEN: Sensitivity; SPE: Specificity.