Demographic and underlying data characteristics
This retrospective study analysed data from 1220 patients who met the Sepsis 3.0 diagnostic criteria after undergoing surgery, using the MIMIC public database. Of these patients, 301 had an average oxygen partial pressure within the normal range within 48 hours of surgery, while 919 developed hyperoxaemia postoperatively. Table 1 presents baseline data, first-day laboratory indicators, and first-day vital signs of all patients included in the study after admission to the ICU. The mean age of patients with hyperoxemia (59.23 ± 17.88) was lower than that of patients with normal oxygen partial pressure (61.63 ± 16.82). When comparing the admission PaO2 levels between the two groups, it was found that the patients with normal oxygen partial pressure had levels closer to the normal range (113.53 ± 42.16 vs 164.44 ± 62.03, p<0.001). Patients with hyperoxemia had a less severe assessment of disease compared to patients with normal partial pressure of oxygen. This was evidenced by lower 90-day mortality rates (23.72% vs 32.23%), lower SOFA scores (6.28 ± 3.35 vs 6.85 ± 3.62), lower Charlson comorbidity index (5.04 ± 3.05 vs 5.44 ± 2.82), and lower LODS (7.08 ± 3.26 vs 8.03 ± 3.29). The admission conditions showed a lower proportion of patients with hyperoxemia who had acute renal failure (43.31% vs 53.82%) and acute respiratory failure (53.65% vs 68.77%). No significant differences were found in other covariates (P > 0.05).
Table 1.Comparisons of baseline characteristics between Normoxemia and Hyperoxemia
Variables
|
Total
|
Normoxemia
|
Hyperoxemia
|
P Value
|
(n = 1220)
|
(n = 301)
|
1 (n = 919)
|
Age (years)
|
59.82 ± 17.65
|
61.63 ± 16.82
|
59.23 ± 17.88
|
0.041
|
Height (cm)
|
169.66 ± 11.89
|
169.34 ± 10.97
|
169.76 ± 12.18
|
0.588
|
Weight (kg)
|
86.33 ± 26.30
|
88.91 ± 28.82
|
85.48 ± 25.38
|
0.066
|
Bmi, Mean ± SD
|
33.49 ± 123.50
|
31.12 ± 10.15
|
34.26 ± 142.18
|
0.702
|
90-days morality,n(%)
|
315 (25.82)
|
97 (32.23)
|
218 (23.72)
|
0.003
|
Gender = M, n(%)
|
739 (60.57)
|
184 (61.13)
|
555 (60.39)
|
0.820
|
Los Hospital, Mean ± SD
|
22.33 ± 18.88
|
22.07 ± 17.14
|
22.42 ± 19.43
|
0.782
|
Los Icu, Mean ± SD
|
13.34 ± 11.90
|
15.28 ± 13.63
|
12.70 ± 11.22
|
0.003
|
First day laboratory examination
|
|
|
|
|
Sodium (mEq/L)
|
139.01 ± 4.02
|
138.54 ± 4.33
|
139.17 ± 3.90
|
0.027
|
Potassium (mEq/L)
|
4.13 ± 0.50
|
4.14 ± 0.50
|
4.13 ± 0.51
|
0.733
|
Chloride (mEq/L)
|
105.97 ± 5.20
|
104.57 ± 5.63
|
106.43 ± 4.96
|
<.001
|
Calcium (mg/dL)
|
8.13 ± 0.76
|
8.14 ± 0.75
|
8.13 ± 0.76
|
0.884
|
Platelet (K/uL)
|
213.06 ± 114.21
|
219.28 ± 122.14
|
211.03 ± 111.48
|
0.277
|
WBC (K/uL)
|
13.04 ± 6.90
|
13.39 ± 7.54
|
12.92 ± 6.68
|
0.308
|
RBC (K/uL)
|
3.64 ± 0.67
|
3.64 ± 0.75
|
3.64 ± 0.64
|
0.887
|
PT (sec)
|
15.49 ± 4.93
|
15.83 ± 5.15
|
15.37 ± 4.86
|
0.168
|
PTT (sec)
|
34.12 ± 10.74
|
34.54 ± 12.06
|
33.98 ± 10.27
|
0.431
|
INR
|
1.40 ± 0.47
|
1.43 ± 0.49
|
1.38 ± 0.46
|
0.124
|
PH
|
7.38 ± 0.06
|
7.38 ± 0.06
|
7.38 ± 0.05
|
0.694
|
PCO2 (mmHg)
|
40.37 ± 6.29
|
41.75 ± 6.97
|
39.92 ± 5.98
|
<.001
|
PO2 (mmHg)
|
151.88 ± 61.79
|
113.53 ± 42.16
|
164.44 ± 62.03
|
<.001
|
Hemoglobin (g/dL)
|
10.93 ± 1.96
|
10.95 ± 2.13
|
10.92 ± 1.90
|
0.840
|
Hematocrit (%)
|
32.61 ± 5.73
|
33.13 ± 6.39
|
32.44 ± 5.49
|
0.094
|
MCH (pg)
|
30.17 ± 2.36
|
30.22 ± 2.48
|
30.16 ± 2.32
|
0.686
|
MCHC (%)
|
33.44 ± 1.63
|
33.02 ± 1.72
|
33.57 ± 1.58
|
<.001
|
MCV (fL)
|
90.35 ± 6.52
|
91.61 ± 6.51
|
89.94 ± 6.47
|
<.001
|
Creatinine (mg/dL)
|
1.33 ± 1.20
|
1.37 ± 1.33
|
1.31 ± 1.15
|
0.459
|
BUN (mg/dL)
|
24.42 ± 18.52
|
25.53 ± 17.65
|
24.06 ± 18.79
|
0.234
|
RDW (%)
|
15.01 ± 1.96
|
15.19 ± 2.18
|
14.95 ± 1.88
|
0.092
|
Severity of organ dysfunction
|
|
|
|
|
Charlson comorbidity
|
5.14 ± 3.00
|
5.44 ± 2.82
|
5.04 ± 3.05
|
0.039
|
SAPSII
|
41.64 ± 14.72
|
42.86 ± 15.64
|
41.24 ± 14.39
|
0.098
|
SOFA
|
6.42 ± 3.43
|
6.85 ± 3.62
|
6.28 ± 3.35
|
0.012
|
OASIS
|
39.93 ± 8.69
|
40.57 ± 8.78
|
39.72 ± 8.65
|
0.141
|
LODS
|
7.32 ± 3.29
|
8.03 ± 3.29
|
7.08 ± 3.26
|
<.001
|
First day vitalsign
|
|
|
|
|
Heart Rate(bpm)
|
90.66 ± 17.46
|
92.78 ± 18.27
|
89.97 ± 17.15
|
0.015
|
SBP(mmHg)
|
117.97 ± 15.91
|
116.80 ± 16.22
|
118.35 ± 15.79
|
0.140
|
DBP(mmHg)
|
62.20 ± 9.99
|
62.35 ± 10.38
|
62.15 ± 9.87
|
0.761
|
MBP(mmHg)
|
78.88 ± 10.41
|
77.97 ± 10.80
|
79.18 ± 10.26
|
0.081
|
Resp Rate(bpm)
|
19.64 ± 4.05
|
20.63 ± 4.47
|
19.32 ± 3.84
|
<.001
|
Temperature(℃)
|
37.06 ± 0.63
|
37.07 ± 0.63
|
37.05 ± 0.64
|
0.631
|
Spo2, n (%)
|
97.57 ± 2.10
|
96.46 ± 2.18
|
97.93 ± 1.94
|
<.001
|
Glucose(mg/dL)
|
147.00 ± 40.05
|
144.86 ± 46.13
|
147.70 ± 37.85
|
0.336
|
surgery_po2_48h (mmHg)
|
141.00 ± 55.23
|
84.80 ± 10.94
|
159.41 ± 51.35
|
<.001
|
Fio2, n(%)
|
36.14 ± 21.54
|
34.72 ± 20.23
|
36.61 ± 21.95
|
0.188
|
PaO2/FiO2, Mean ± SD
|
500.28 ± 291.15
|
307.04 ± 123.85
|
563.58 ± 302.15
|
<.001
|
IMV, n(%)
|
|
|
|
0.188
|
NO
|
5 (0.41)
|
3 (1.00)
|
2 (0.22)
|
|
YES
|
1215 (99.59)
|
298 (99.00)
|
917 (99.78)
|
|
RRT, n(%)
|
|
|
|
0.091
|
NO
|
1064 (87.21)
|
254 (84.39)
|
810 (88.14)
|
|
YES
|
156 (12.79)
|
47 (15.61)
|
109 (11.86)
|
|
Vasoactive, n(%)
|
|
|
|
0.191
|
NO
|
423 (34.67)
|
95 (31.56)
|
328 (35.69)
|
|
YES
|
797 (65.33)
|
206 (68.44)
|
591 (64.31)
|
|
Ventilation status
|
|
|
|
|
Invasivevent, n(%)
|
|
|
|
0.449
|
NO
|
120 (9.84)
|
33 (10.96)
|
87 (9.47)
|
|
YES
|
1100 (90.16)
|
268 (89.04)
|
832 (90.53)
|
|
Oxygen, n(%)
|
|
|
|
0.121
|
NO
|
323 (26.48)
|
90 (29.90)
|
233 (25.35)
|
|
YES
|
897 (73.52)
|
211 (70.10)
|
686 (74.65)
|
|
Noninvasivevent, n(%)
|
|
|
|
0.094
|
NO
|
1191 (97.62)
|
290 (96.35)
|
901 (98.04)
|
|
YES
|
29 (2.38)
|
11 (3.65)
|
18 (1.96)
|
|
Highflow, n(%)
|
|
|
|
<.001
|
NO
|
1109 (90.90)
|
259 (86.05)
|
850 (92.49)
|
|
YES
|
111 (9.10)
|
42 (13.95)
|
69 (7.51)
|
|
Trach, n(%)
|
|
|
|
<.001
|
NO
|
1136 (93.11)
|
264 (87.71)
|
872 (94.89)
|
|
YES
|
84 (6.89)
|
37 (12.29)
|
47 (5.11)
|
|
Commorbity
|
|
|
|
|
AMI, n(%)
|
|
|
|
0.881
|
NO
|
1209 (99.10)
|
299 (99.34)
|
910 (99.02)
|
|
YES
|
11 (0.90)
|
2 (0.66)
|
9 (0.98)
|
|
Coronary Atherosclerosis, n (%)
|
|
|
|
0.690
|
NO
|
1004 (82.30)
|
250 (83.06)
|
754 (82.05)
|
|
YES
|
216 (17.70)
|
51 (16.94)
|
165 (17.95)
|
|
Valve disorder, n(%)
|
|
|
|
0.585
|
NO
|
1143 (93.69)
|
284 (94.35)
|
859 (93.47)
|
|
YES
|
77 (6.31)
|
17 (5.65)
|
60 (6.53)
|
|
AKI, n(%)
|
|
|
|
0.001
|
NO
|
660 (54.10)
|
139 (46.18)
|
521 (56.69)
|
|
YES
|
560 (45.90)
|
162 (53.82)
|
398 (43.31)
|
|
ARF, n(%)
|
|
|
|
<.001
|
NO
|
520 (42.62)
|
94 (31.23)
|
426 (46.35)
|
|
YES
|
700 (57.38)
|
207 (68.77)
|
493 (53.65)
|
|
Diabete, n(%)
|
|
|
|
0.075
|
NO
|
829 (67.95)
|
192 (63.79)
|
637 (69.31)
|
|
YES
|
391 (32.05)
|
109 (36.21)
|
282 (30.69)
|
|
Hypertension, n(%)
|
|
|
|
0.204
|
NO
|
492 (40.33)
|
112 (37.21)
|
380 (41.35)
|
|
YES
|
728 (59.67)
|
189 (62.79)
|
539 (58.65)
|
|
Abbreviations: MAP: Mean Arterial Pressure. SpO2: Peripheral Capillary Oxygen Saturation. SOFA: Sequential Organ Failure Assessment. SAPS II: Simplified Acute Physiology Score II. OASIS: Oxford Acute Disease Severity. LODS: Logistic organ insufficiency. Ventilation Status: The condition that the patient has received corresponding oxygen therapy in this study. AMI:Acute Myocardial Infarction. VD:Valve disorder. AKI:Acute Kidney Injury. ARF:Acute Respiratory Failure.
The association between post-surgery hyperxemia and mortality outcomes
The restricted cubic spline model in this study reveals a U-shaped association between post-surgeryarterial oxygen partial pressure levels and all-cause mortality, as demonstrated in Figure 2. The patients were divided into three groups based on their PaO2 value at HR = 1 in the study results of the 90-day mortality rate in the restricted cubic spline: the normal oxygen partial pressure group (PaO2 ≤128.7mmHg), the mild hyperoxemia group (128.7mmHg < PaO2 < 162.1mmHg), and the severe hyperoxemia group (PaO2 ≥ 162.1mmHg). After regrouping, we reconstructed Table 2 with the patient's baseline data. The study shows that the mortality rate is lower (P < 0.05) when the patient's oxygen partial pressure is between 128.7mmHg and 162.1mmHg, as calculated by RCS, compared to the other two groups.
The patient's baseline data was recreated based on the PaO2 value taken in the restricted cubic spline model of their 90-day mortality rate. Table 2 shows that 611 people had a post-surgeryoxygen partial pressure less than 128.7mmHg, 269 people were in the mild hyperoxemia group, and 340 people were in the severe hyperoxemia group. The study cohort reveals that patients with mild and severe hyperoxemia are younger than the normal group and have a lower 90-day mortality rate. Additionally, they exhibit similar disease severity scores, including lower SOFA, OASIS, and LODS scores. Regarding admission conditions, patients with mild and severe hyperoxemia exhibited similar statistical significance in relation to acute respiratory failure, acute renal failure, diabetes, hypertension, and other conditions (P<0.01).
Table 2. Basic data table after grouping using restricted cubic splines
Variables
|
Total
|
Normoxemia
|
Mild hyperoxemia
|
Severe hyperoxemia
|
P Value
|
(n = 1220)
|
(n = 611)
|
(n = 269)
|
(n = 340)
|
Age (years)
|
59.82 ± 17.65
|
61.57 ± 16.75
|
61.33 ± 16.87
|
55.49 ± 19.09
|
<.001
|
Height (cm)
|
169.66 ± 11.89
|
170.15 ± 10.87
|
169.26 ± 14.86
|
169.10 ± 10.98
|
0.353
|
Weight (kg)
|
86.33 ± 26.30
|
89.63 ± 28.47
|
85.15 ± 20.84
|
81.32 ± 25.29
|
<.001
|
Bmi, Mean ± SD
|
33.49 ± 123.50
|
30.89 ± 9.39
|
45.77 ± 262.45
|
28.42 ± 8.43
|
0.173
|
90-days morality, n(%)
|
315 (25.82)
|
181 (29.62)
|
51 (18.96)
|
83 (24.41)
|
0.003
|
Los Hospital, Mean ± SD
|
22.33 ± 18.88
|
23.14 ± 18.73
|
21.38 ± 17.60
|
21.62 ± 20.10
|
0.32
|
Los Icu, Mean ± SD
|
13.34 ± 11.90
|
15.35 ± 13.18
|
11.89 ± 9.72
|
10.87 ± 10.35
|
<.001
|
First day laboratory examination
|
|
|
|
|
|
Sodium (mEq/L)
|
139.01 ± 4.02
|
138.72 ± 4.24
|
139.05 ± 3.72
|
139.51 ± 3.79
|
0.013
|
Potassium (mEq/L)
|
4.13 ± 0.50
|
4.15 ± 0.53
|
4.09 ± 0.47
|
4.12 ± 0.48
|
0.210
|
Chloride (mEq/L)
|
105.97 ± 5.20
|
105.18 ± 5.54
|
106.20 ± 4.48
|
107.22 ± 4.83
|
<.001
|
Calcium (mg/dL)
|
8.13 ± 0.76
|
8.10 ± 0.76
|
8.13 ± 0.68
|
8.19 ± 0.81
|
0.218
|
Platelet (K/uL)
|
213.06 ± 114.21
|
213.94 ± 108.88
|
210.46 ± 127.38
|
213.56 ± 112.85
|
0.913
|
WBC (K/uL)
|
13.04 ± 6.90
|
13.46 ± 7.49
|
12.70 ± 6.28
|
12.55 ± 6.20
|
0.094
|
RBC (K/uL)
|
3.64 ± 0.67
|
3.65 ± 0.71
|
3.69 ± 0.62
|
3.58 ± 0.63
|
0.106
|
PT (sec)
|
15.49 ± 4.93
|
15.87 ± 5.28
|
15.13 ± 4.07
|
15.07 ± 4.87
|
0.022
|
PTT (sec)
|
34.12 ± 10.74
|
34.24 ± 11.18
|
33.69 ± 10.39
|
34.24 ± 10.21
|
0.761
|
INR
|
1.40 ± 0.47
|
1.43 ± 0.51
|
1.37 ± 0.41
|
1.35 ± 0.43
|
0.021
|
PH
|
7.38 ± 0.06
|
7.37 ± 0.06
|
7.38 ± 0.06
|
7.38 ± 0.05
|
0.031
|
PCO2 (mmHg)
|
40.37 ± 6.29
|
41.32 ± 6.63
|
40.06 ± 5.86
|
38.91 ± 5.65
|
<.001
|
PO2 (mmHg)
|
151.88 ± 61.79
|
120.90 ± 39.42
|
151.19 ± 50.30
|
208.10 ± 63.50
|
<.001
|
Hemoglobin (g/dL)
|
10.93 ± 1.96
|
10.93 ± 2.08
|
11.11 ± 1.92
|
10.78 ± 1.76
|
0.107
|
Hematocrit (%)
|
32.61 ± 5.73
|
32.90 ± 6.14
|
33.03 ± 5.48
|
31.78 ± 5.06
|
0.006
|
MCH (pg)
|
30.17 ± 2.36
|
30.08 ± 2.43
|
30.23 ± 2.26
|
30.29 ± 2.31
|
0.359
|
MCHC (%)
|
33.44 ± 1.63
|
33.18 ± 1.61
|
33.48 ± 1.62
|
33.87 ± 1.58
|
<.001
|
MCV (fL)
|
90.35 ± 6.52
|
90.73 ± 6.48
|
90.47 ± 6.41
|
89.59 ± 6.62
|
0.034
|
Creatinine (mg/dL)
|
1.33 ± 1.20
|
1.38 ± 1.23
|
1.39 ± 1.20
|
1.20 ± 1.13
|
0.060
|
BUN (mg/dL)
|
24.42 ± 18.52
|
26.39 ± 19.28
|
24.91 ± 18.79
|
20.51 ± 16.20
|
<.001
|
RDW (%)
|
15.01 ± 1.96
|
15.07 ± 1.99
|
14.98 ± 1.85
|
14.93 ± 1.98
|
0.581
|
Severity of organ dysfunction
|
|
|
|
|
|
Charlson comorbidity
|
5.14 ± 3.00
|
5.33 ± 2.87
|
5.35 ± 2.94
|
4.63 ± 3.23
|
0.001
|
SAPSII
|
41.64 ± 14.72
|
42.45 ± 14.69
|
41.53 ± 14.32
|
40.26 ± 15.01
|
0.088
|
SOFA
|
6.42 ± 3.43
|
6.83 ± 3.57
|
6.41 ± 3.25
|
5.69 ± 3.19
|
<.001
|
OASIS
|
39.93 ± 8.69
|
40.76 ± 8.82
|
39.11 ± 8.74
|
39.09 ± 8.27
|
0.004
|
LODS
|
7.32 ± 3.29
|
7.91 ± 3.29
|
6.96 ± 3.26
|
6.54 ± 3.13
|
<.001
|
First day vitalsign
|
|
|
|
|
|
Heart Rate(bpm)
|
90.66 ± 17.46
|
91.20 ± 17.98
|
88.84 ± 15.99
|
91.13 ± 17.59
|
0.153
|
SBP(mmHg)
|
117.97 ± 15.91
|
117.29 ± 16.10
|
118.37 ± 16.18
|
118.86 ± 15.32
|
0.310
|
DBP(mmHg)
|
62.20 ± 9.99
|
61.92 ± 10.16
|
61.37 ± 9.51
|
63.34 ± 9.98
|
0.033
|
MBP(mmHg)
|
78.88 ± 10.41
|
77.88 ± 10.25
|
78.90 ± 10.48
|
80.67 ± 10.41
|
<.001
|
Resp Rate(bpm)
|
19.64 ± 4.05
|
20.37 ± 4.23
|
19.28 ± 3.68
|
18.61 ± 3.71
|
<.001
|
Temperature(℃)
|
37.06 ± 0.63
|
37.05 ± 0.65
|
37.10 ± 0.63
|
37.04 ± 0.61
|
0.422
|
Spo2, n (%)
|
97.57 ± 2.10
|
96.94 ± 2.06
|
97.72 ± 2.23
|
98.58 ± 1.60
|
<.001
|
Glucose(mg/dL)
|
147.00 ± 40.05
|
146.60 ± 43.63
|
147.59 ± 36.46
|
147.24 ± 35.93
|
0.935
|
surgery_po2_48h (mmHg)
|
141.00 ± 55.23
|
99.79 ± 17.57
|
143.62 ± 9.25
|
212.98 ± 45.64
|
<.001
|
Fio2, n(%)
|
36.14 ± 21.54
|
35.78 ± 21.00
|
35.90 ± 21.08
|
36.98 ± 22.86
|
0.701
|
PaO2/FiO2, Mean ± SD
|
500.28 ± 291.15
|
355.16 ± 156.15
|
511.09 ± 208.19
|
752.53 ± 353.27
|
<.001
|
Gender, n(%)
|
|
|
|
|
0.085
|
F
|
481 (39.43)
|
228 (37.32)
|
102 (37.92)
|
151 (44.41)
|
|
M
|
739 (60.57)
|
383 (62.68)
|
167 (62.08)
|
189 (55.59)
|
|
RRT, n(%)
|
|
|
|
|
0.003
|
NO
|
1064 (87.21)
|
513 (83.96)
|
243 (90.33)
|
308 (90.59)
|
|
YES
|
156 (12.79)
|
98 (16.04)
|
26 (9.67)
|
32 (9.41)
|
|
Vasoactive, n(%)
|
|
|
|
|
0.095
|
NO
|
423 (34.67)
|
197 (32.24)
|
107 (39.78)
|
119 (35.00)
|
|
YES
|
797 (65.33)
|
414 (67.76)
|
162 (60.22)
|
221 (65.00)
|
|
Ventilation status
|
|
|
|
|
|
Invasivevent, n(%)
|
|
|
|
|
0.689
|
NO
|
120 (9.84)
|
59 (9.66)
|
30 (11.15)
|
31 (9.12)
|
|
YES
|
1100 (90.16)
|
552 (90.34)
|
239 (88.85)
|
309 (90.88)
|
|
Oxygen, n(%)
|
|
|
|
|
0.108
|
NO
|
323 (26.48)
|
173 (28.31)
|
58 (21.56)
|
92 (27.06)
|
|
YES
|
897 (73.52)
|
438 (71.69)
|
211 (78.44)
|
248 (72.94)
|
|
Noninvasivevent, n(%)
|
|
|
|
|
0.353
|
NO
|
1191 (97.62)
|
593 (97.05)
|
263 (97.77)
|
335 (98.53)
|
|
YES
|
29 (2.38)
|
18 (2.95)
|
6 (2.23)
|
5 (1.47)
|
|
Highflow, n(%)
|
|
|
|
|
0.009
|
NO
|
1109 (90.90)
|
541 (88.54)
|
247 (91.82)
|
321 (94.41)
|
|
YES
|
111 (9.10)
|
70 (11.46)
|
22 (8.18)
|
19 (5.59)
|
|
Trach, n(%)
|
|
|
|
|
<.001
|
NO
|
1136 (93.11)
|
547 (89.53)
|
254 (94.42)
|
335 (98.53)
|
|
YES
|
84 (6.89)
|
64 (10.47)
|
15 (5.58)
|
5 (1.47)
|
|
Commorbity
|
|
|
|
|
|
AMI, n(%)
|
|
|
|
|
0.790
|
NO
|
1209 (99.10)
|
605 (99.02)
|
266 (98.88)
|
338 (99.41)
|
|
YES
|
11 (0.90)
|
6 (0.98)
|
3 (1.12)
|
2 (0.59)
|
|
Coronary Atherosclerosis, n (%)
|
|
|
|
|
<.001
|
NO
|
1004 (82.30)
|
500 (81.83)
|
202 (75.09)
|
302 (88.82)
|
|
YES
|
216 (17.70)
|
111 (18.17)
|
67 (24.91)
|
38 (11.18)
|
|
Valve disorder, n(%)
|
|
|
|
|
0.356
|
NO
|
1143 (93.69)
|
575 (94.11)
|
247 (91.82)
|
321 (94.41)
|
|
YES
|
77 (6.31)
|
36 (5.89)
|
22 (8.18)
|
19 (5.59)
|
|
AKI, n(%)
|
|
|
|
|
<.001
|
NO
|
660 (54.10)
|
293 (47.95)
|
151 (56.13)
|
216 (63.53)
|
|
YES
|
560 (45.90)
|
318 (52.05)
|
118 (43.87)
|
124 (36.47)
|
|
ARF, n(%)
|
|
|
|
|
<.001
|
NO
|
520 (42.62)
|
200 (32.73)
|
136 (50.56)
|
184 (54.12)
|
|
YES
|
700 (57.38)
|
411 (67.27)
|
133 (49.44)
|
156 (45.88)
|
|
Diabete, n(%)
|
|
|
|
|
<.001
|
NO
|
829 (67.95)
|
388 (63.50)
|
176 (65.43)
|
265 (77.94)
|
|
YES
|
391 (32.05)
|
223 (36.50)
|
93 (34.57)
|
75 (22.06)
|
|
Hypertension, n(%)
|
|
|
|
|
0.010
|
NO
|
492 (40.33)
|
241 (39.44)
|
93 (34.57)
|
158 (46.47)
|
|
YES
|
728 (59.67)
|
370 (60.56)
|
176 (65.43)
|
182 (53.53)
|
|
Abbreviations: MAP: Mean Arterial Pressure. SpO2: Peripheral Capillary Oxygen Saturation. SOFA: Sequential Organ Failure Assessment. SAPS II: Simplified Acute Physiology Score II. OASIS: Oxford Acute Disease Severity. LODS: Logistic organ insufficiency. Ventilation Status: The condition that the patient has received corresponding oxygen therapy in this study. AMI:Acute Myocardial Infarction. VD:Valve disorder. AKI: Acute Kidney Injury. ARF:Acute Respiratory Failure.
Clinical outcomes
After plotting the KM survival curve(Figure 3), we found that there were significant differences in the survival probability differences of the two groups of patients at 90 days, 180 days, and 365 days (P < 0.05). The survival probability of the patient group with hyperoxemia after surgery was significantly higher than that of the control group, but there was no statistical significance in the short-term survival analysis.
To determine whether mild to severe hyperxemia, based on RCS grouping, is an independent risk factor for increased all-cause mortality in postoperative patients, we conducted univariate and multivariate Cox regression analyses in Figure 4. The results of the univariate model showed a close relationship between mild (OR:0.56; HR: 0.39-0.79, P = 0.001) after RCS analysis and 90-day mortality. After adjusting for other confounding factors in the multivariate model, there remained a significant correlation(OR:0.54; HR: 0.34-0.86, P = 0.01) between mild hyperxemia patients and 90-day mortality after RCS analysis. However, no significant statistical significance was found in severe hyperxemia patients.
Subgroup analysis and forest mapping
Figure 5shows that after grouping using RCS, the correlation between the level of oxygen partial pressure and the 90-day all-cause mortality rate in patients with sepsis after surgery remains stable in all subgroups. We conducted a stratified analysis forest plot for age, gender, SOFA score, blood oxygen saturation, and oxygen partial pressure grouped using traditional methods. The results show that except for age and SOFA score, the level of oxygen partial pressure grouped by RCS is an independent influencing factor.