In total, 314 patients were included in the study. Among them, 134 were excluded, and 180 patients were finally included in the analysis. There were 98 and 82 patients in the NIVATS and IVATS groups, respectively. The two groups differed in terms of baseline characteristics, diagnosis, and procedure. The NIVATS group was younger and had a lower incidence of comorbidities than the IVATS group. Moreover, the NIVATS group frequently diagnosed with benign lesion and underwent wedge resection. After a propensity score matching, both groups were found to have similar characteristics including age, body mass index, sex, smoking status, comorbidities, diagnosis, and thoracic procedure. The number of patients decreased to 52 per group (Table 1).
Table 1
Patient characteristics before and after propensity score matching according to anesthesia technique.
Variables
|
Before Propensity Score Matching
|
After Propensity Score Matching
|
(Full Patient Cohort)
|
(Propensity Score Matched Patient Cohort)
|
NIVATS
(n=98)
|
IVATS
(n=82)
|
p-value
|
STD
|
NIVATS
(n=52)
|
IVATS
(n=52)
|
p-value
|
STD
|
Age (years); median (P25 - P75)
|
54 (38.8 - 65)
|
60 (44.8 - 69.3)
|
0.034*
|
-0.309
|
55 (43.5 - 65.5)
|
59.5 (40.5 - 68)
|
0.492
|
-0.129
|
Gender; n (%)
|
|
|
0.663
|
0.065
|
|
|
0.693
|
0.078
|
Male
|
47 (48%)
|
42 (51.2%)
|
|
|
22 (42.3%)
|
24 (46.2%)
|
|
|
Female
|
51 (52%)
|
40 (48.8%)
|
|
|
30 (57.7%)
|
28 (53.9%)
|
|
|
BMI (kg/m2); median (P25 - P75)
|
22.1 (19.6 - 24.7)
|
22.8 (20.2 - 26.7)
|
0.179
|
-0.212
|
22.6 (19.8 - 24.9)
|
22.2 (18.7 - 26.5)
|
0.818
|
0.024
|
Smoking status; n (%)
|
|
|
0.721
|
0.053
|
|
|
0.426
|
0.156
|
Non-smoker
|
78 (79.6%)
|
67 (81.7%)
|
|
|
45 (86.5%)
|
42 (80.8%)
|
|
|
Smoker
|
20 (20.4%)
|
15 (18.3%)
|
|
|
7 (13.5%)
|
10 (19.2%)
|
|
|
Underlying disease; n (%)
|
|
|
|
|
|
|
|
|
Diabetes mellitus
|
22 (22.4%)
|
19 (23.2%)
|
0.908
|
-0.017
|
13 (25%)
|
11 (21.2%)
|
0.642
|
0.039
|
Hypertension
|
30 (30.6%)
|
39 (47.6%)
|
0.020*
|
-0.351
|
20 (38.5%)
|
21 (40.4%)
|
0.841
|
0.000
|
Dyslipidemia
|
21 (21.4%)
|
28 (34.1%)
|
0.056
|
-0.285
|
12 (23.1%)
|
12 (23.1%)
|
1.000
|
0.000
|
Cardiovascular disease
|
0 (0%)
|
5 (6.1%)
|
0.018*
|
-0.358
|
0 (0%)
|
0 (0%)
|
|
|
Cerebrovascular disease
|
1 (1%)
|
5 (6.1%)
|
0.094
|
-0.275
|
1 (1.9%)
|
1 (1.9%)
|
1.000
|
0.000
|
COPD
|
3 (3.1%)
|
9 (11%)
|
0.040*
|
-0.312
|
3 (5.8%)
|
2 (3.9%)
|
0.647
|
0.090
|
Diagnosis; n (%)
|
|
|
0.022*
|
0.349
|
|
|
|
|
Malignant
|
61 (62.2%)
|
64 (78.1%)
|
|
|
36 (69.2%)
|
37 (71.2%)
|
0.830
|
0.042
|
Benign
|
37 (37.7%)
|
18 (21.9%)
|
|
|
16 (30.8%)
|
15 (28.9%)
|
0.596
|
|
Procedure; n (%)
|
|
|
0.000*
|
0.600
|
|
|
0.596
|
0.200
|
Wedge
|
78 (79.6%)
|
43 (52.4%)
|
|
|
37 (71.2%)
|
37 (71.2%)
|
|
|
Segmentectomy
|
2 (2%)
|
5 (6.1%)
|
|
|
1 (1.9%)
|
0 (0%)
|
|
|
Lobectomy
|
18 (18.4%)
|
34 (41.5%)
|
|
|
14 (27%)
|
15 (27.9%)
|
|
|
Abbreviation: STD, standardized difference; NIVATS, Non-intubated video-assisted thoracoscopic surgery; IVATS, General anesthesia with intubation and controlled ventilation for video-assisted thoracoscopic surgery; BMI, body mass index; COPD, chronic obstructive pulmonary disease.
In terms of anesthetic outcomes, both groups did not present with desaturation. The lowest SpO2 between the two groups did not significantly differ (96.5% vs. 99%, p = 0.185). By contrast, the NIVATS group had a significantly higher ETco2 peak than the IVATS group (43 vs. 36 mmHg, p < 0.001) (Table 2). The ETco2 of NIVATS group was significantly higher than that of IVATS group.. The anesthetic induction time of the NIVATS group was significantly shorter than that of the IVATS group (10 vs. 15 min, p = 0.005) (Table 2). There was no difference in the overall anesthetic induction and operative time between the two groups.
Table 2
Peri-operative outcomes between two anesthesia technique.
Variables
|
Before Propensity Score Matching
|
After Propensity Score Matching
|
(Full Patient Cohort)
|
|
(Propensity Score Matched Patient Cohort)
|
NIVATS
(n=98)
|
IVATS
(n=82)
|
p-value
|
STD
|
NIVATS
(n=52)
|
IVATS
(n=52)
|
p-value
|
STD
|
Anesthetic induction time (min);
median (P25 - P75)
|
10 (5 - 15)
|
13.5 (10 - 20)
|
0.009*
|
-0.318
|
10 (5 - 15)
|
15 (10 - 20)
|
0.005*
|
-0.534
|
Overall anesthetic time (min);
median (P25 - P75)
|
125 (90 - 201.3)
|
122.5 (95 - 171.3)
|
0.725
|
0.083
|
145 (97.5 - 210)
|
127.5 (105 - 175)
|
0.651
|
0.121
|
Operative time (min);
median (P25 - P75)
|
60 (40 - 95)
|
112.5 (63.8 - 171.3)
|
0.000*
|
-0.701
|
67.5 (40 - 107.5)
|
80 (55 - 167.5)
|
0.059
|
-0.368
|
Anesthetic results
|
|
|
|
|
|
|
|
|
Prevalence of desaturation
|
0 (0%)
|
0 (0%)
|
|
|
0 (0%)
|
0 (0%)
|
|
|
The lowest intraoperative SpO2 (%); median (P25 - P75)
|
100 (96.8 - 100)
|
99.5 (95.8 - 100)
|
0.056
|
0.097
|
96.5 (92 - 100)
|
99 (97 - 100)
|
0.185
|
-0.056
|
The highest intraoperative ETCO2 (mmHg); median (P25 - P75)
|
44 (40 - 48)
|
36.5 (34 - 40)
|
0.000*
|
0.837
|
43 (40.5 - 48)
|
36 (34 - 41)
|
0.000*
|
0.655
|
Surgical results
|
|
|
|
|
|
|
|
|
Blood loss (ml); median (P25 - P75)
|
20 (10 - 50)
|
50 (10 - 150)
|
0.000*
|
-0.531
|
20 (10 - 50)
|
50 (10 - 125)
|
0.008*
|
-0.534
|
Blood transfusion; n (%)
|
1 (1%)
|
4 (4.9%)
|
0.179
|
0.23
|
0 (0%)
|
3 (5.8%)
|
0.079
|
0.350
|
Tubeless surgery; median (P25 - P75)
|
3 (3 - 5)
|
5 (4 - 8.3)
|
0.000*
|
-0.543
|
3 (3 - 4)
|
5 (4 -7)
|
< 0.001*
|
-0.408
|
Complications
|
|
|
|
|
|
|
|
|
Conversion to GAVATS; n (%)
|
6 (6.1%)
|
0 (0%)
|
0.032*
|
0.361
|
4 (7.7%)
|
0 (0%)
|
0.041*
|
0.408
|
Sore throat; n (%)
|
0 (0%)
|
10 (12.2%)
|
0.000*
|
0.527
|
0 (0%)
|
7 (13.5%)
|
0.006*
|
0.558
|
Other anesthetic complication; n (%)
|
4 (4.1%)
|
0 (0%)
|
0.127
|
0.292
|
2 (3.9%)
|
0 (0%)
|
0.153
|
0.283
|
Reoperation; n (%)
|
2 (2%)
|
1 (1.2%)
|
1.000
|
0.065
|
0 (0%)
|
0 (0%)
|
|
|
Pneumonia; n (%)
|
0 (0%)
|
0 (0%)
|
|
|
0 (0%)
|
0 (0%)
|
|
|
Chest radiograph results; n (%)
|
|
|
0.749
|
0.047
|
|
|
0.169
|
0.270
|
Normal
|
92 (93.9%)
|
76 (92.7%)
|
|
|
51 (98.1%)
|
48 (92.3%)
|
|
|
Atelectasis
|
6 (6.1%)
|
6 (6.1%)
|
|
|
1 (1.92%)
|
4 (7.7%)
|
|
|
Hospital stays (day); median (P25 - P75)
|
5 (4 - 7.3)
|
7 (5 - 11)
|
0.000*
|
-0.426
|
5 (4 - 7)
|
6 (5 - 10)
|
0.004*
|
-0.341
|
Mortality; n (%)
|
0 (0%)
|
0 (0%)
|
|
|
0 (0%)
|
0 (0%)
|
|
|
Abbreviation: STD, standardized difference; NIVATS, Non-intubated video-assisted thoracoscopic surgery; IVATS, General anesthesia with intubation and controlled ventilation for video-assisted thoracoscopic surgery; SpO2, oxygen saturation; ETCO2, end-tidal carbon dioxide.
In terms of surgical outcomes, the NIVATS group had a significantly lower volume of blood loss and a shorter length of hospital stay than the IVATS group (20 vs. 50 mL, p = 0.008 and 5 vs. 6 days, p = 0.004). There was no mortality in both groups.
In the regression analysis, the NIVATS group had a significantly shorter anesthetic induction time and lower volume of blood loss but a higher intraoperative ETCO2 than the IVATS group (Table 3).
Table 3
Multiple linear regression analysis of each outcome variable comparing between NIVATS and IVATS
Outcome variables
|
Mean difference
|
95% CI
|
p - value
|
Anesthetic induction time (min);
|
-5.135
|
(- 8.878)- (-1.391)
|
0.008*a
|
The highest intraoperative ETCO2 (mmHg);
|
4.561
|
1.852 - 7.269
|
0.001*b
|
Estimate blood loss (ml);
|
-75.565
|
(- 131.08) - (- 20.65)
|
0.008*c
|
Hospital stays (day);
|
-1.923
|
(- 3.912) - 0.027
|
0.053d
|
Notes: Analyzed by Multiple Linear Regression model
a Adjusted by Age, BMI, Gender, Smoking status and Diagnosis.
b Adjusted by Age, Gender, DM, HT, Stroke and operation time.
c Adjusted by Age, Gender, BMI and Procedure.
d Adjusted by Age, Gender, Procedure, Conversion to GAVATS, Sore throat and Other anesthetic complication.
In terms of postoperative complications, four patients in the NIVATS group required conversion to intubation with controlled ventilation during surgery (7.7%, p = 0.041). The reasons for conversion were difficulties using the surgical technique due to factors such as severe calcified lymph node and bleeding. In total, seven patients in the IVATS group, but none in the NIVATS group, experienced sore throat (13.5% vs. 0%, p = 0.006). There was no difference in terms of other anesthetic complications between the two groups. None of the patients had postoperative pneumonia or reoperation. There was no difference in terms of atelectasis on postoperative chest radiography between the two groups.