Intraoperative Oxygen Concentration and Postoperative Delirium After Laparoscopic Gastric and Colorectal Malignancies Surgery: A Randomized, Double-Blind, Controlled Trial

Figures & data

Figure 1 Flow chart of the trial.

Abbreviations: FiO₂, fraction of inspired oxygen; SpO₂, oxygen saturation; h, hour.

Table 1 Characteristics of Participants

Characteristics	Group A	Group B	P value
Age (year), mean ± SD	71.39±2.80	71.45±3.85	0.805
Gender, n (%)	144 (45.85%)	149 (47.15%)	0.752
Years of education (year), n (%)
0, n (%)	2 (0.64%)	2 (0.63%)	1.001
1 to 9, n (%)	31 (9.87%)	33 (10.44%)	0.816
10 to 13, n (%)	104 (33.12%)	104 (32.91%)	0.965
14 to 17, n (%)	93 (29.62%)	94 (29.75%)	0.978
>17, n (%)	15 (4.78%)	18 (5.70%)	0.612
Height (cm), mean ± SD	170.13±3.02	170.41±3.05	0.257
Body weight (kg), mean ± SD	68.87±2.32	68.71±2.19	0.374
BMI (kg/m2), mean ± SD	22.75±1.25	22.76±1.31	0.864
Dependence on smoking (n), n (%)	74 (23.57%)	73 (23.10%)	0.893
Alcohol abuse, n (%)	17 (5.41%)	20 (6.32%)	0.637
Coronary heart disease, n (%)	37 (11.78%)	39 (12.34%)	0.832
Hypertension, n (%)	123 (39.17%)	108 (34.18%)	0.195
Diabetes, n (%)	63 (20.06%)	72 (22.78%)	0.412
Radical gastrectomy for gastric cancer, n (%)	68 (21.66%)	74 (23.42%)	0.603
Radical resection of colon cancer, n (%)	127 (40.45%)	131 (41.46%)	0.802
Radical resection of rectal cancer, n (%)	119 (37.90%)	111 (35.13%)	0.472
Preoperative Hb (g/L), median and 25–75 percentile	124 (120–130)	124 (119–134)	0.440
ASA
ASA class I, n (%)	182 (57.96%)	186 (58.86%)	0.962
ASA class II, n (%)	94 (29.94%)	94 (29.75%)	0.814
ASA class III, n (%)	31 (9.87%)	33 (10.44%)	0.891
Time of anesthesia (min), mean ± SD	224.32±5.21	224.38±4.96	0.586
Time of surgery (min), mean ± SD	188.71±8.56	188.23±12.67	0.582
BIS value	48±4	47±3	0.972
Estimated blood loss (mL), mean ± SD	119.11±13.40	117.09±13.55	0.863
VAS score, median and 25–75 percentile	2 (1–3)	2 (1–3)	0.170
Length of PACU stay (min), median and 25–75 percentile	35 (33.75–37.56)	35 (33.37–38.15)	0.592
Length of hospital stay (days)	14.35±1.06	14.30±1.08	0.563
Mortality in 6 months, n (%)	20 (9.35%)	10 (4.67%)	0.421

Note: The values are presented as means ± SD, median (interquartile range), or n (%) depending on type and distribution.

Abbreviations: ASA, American Society of Anesthesiologists; BMI, body mass index; Hb, hemoglobin; PACU, post anesthesia care unit; VAS, visual analogue scale.

Table 2 Postoperative Characteristics of Participants

Characteristics	Group A	Group B	P value
Pneumonia, n (%)	20 (6.36%)	30 (9.49%)	0.552
Wound infection, n (%)	30 (9.55%)	40 (12.65%)	0.741
Cerebral hemorrhage, n (%)	0	0
Cerebral infarction, n (%)	0	0
Myocardial infarction, n (%)	1 (0.32%)	0
Pulmonary embolism, n (%)	0	1 (0.32%)
Reoperation, n (%)	0	1 (0.32%)
Postoperative atelectasis, n (%)	60 (19.11%)	132 (41.77%)	0.026
Incidence of POD, n (%)	64 (20.38%)	58 (18.35%)	0.402

Note: The values are presented as n (%) depending on variable type.

Abbreviation: POD, postoperative delirium.

Figure 2 (A) Comparison of intraoperative PaO₂ at T_1-4 time points in the two groups included. (B) Comparison of intraoperative rSO₂ at T_1-4 time points in the two groups included. (C) Comparison of intraoperative SpO₂ at T_1-4 time points in the two groups included.

Abbreviations: PaO₂, oxygen partial pressure; rSO2, regional cerebral oxygen saturation; SpO₂, oxygen saturation.

Figure 3 Preoperative MMSE and postoperative MDAS score for the study period are presented over time. Values are reported for 40% FiO₂ (circles) and 80% FiO₂ (squares) randomization groups individually.

Abbreviations: MMSE, Mini Mental State Scale; MDAS, Memorial Delirium Assessment Scale.