We analyzed data from 242 consecutive patients who were digitally monitored by Thopaz system after undergoing pulmonary resection during the study period (Fig. 1). Patient characteristics and operative data are presented in Table 1. Of these patients, 25 met the exclusion criteria; nine patients underwent reoperation because of postoperative air leaks (n = 7) or bleeding (n = 2), thirteen patients required pleurodesis, and two patients treated by re-drainage needed additional thoracostomy because of severe subcutaneous emphysema leading to lung expansion failure after surgery. One patient died of perioperative cardiac disease.
Table 1
Patient characteristics and operative data
Characteristics
|
No. (%) (n = 217)
|
Low-pressure suction
(n = 49)
Group A
|
Intermediate-pressure suction
(n = 100)
Group B
|
High-pressure suction
(n = 68)
Group C
|
Sex (males/females)
|
37/12
|
73/27
|
46/22
|
Age (mean ± SD)
|
63.7 ± 19.1
|
54.8 ± 24.2
|
58.2 ± 20.9
|
Primary disease
|
Lung Cancer
|
28
|
47
|
31
|
Metastatic Cancer
|
4
|
2
|
3
|
Pneumothorax
|
14
|
38
|
27
|
Others
|
3
|
13
|
7
|
Comorbidities
|
Emphysema
|
8
|
9
|
7
|
Interstitial pneumonia
|
2
|
4
|
2
|
Diabetes mellitus
|
5
|
9
|
3
|
VATS
|
48 (98)
|
94 (94)
|
66 (97)
|
Surgical procedure
|
Anatomical resection
|
29 (59)
|
47 (47)
|
34 (50)
|
Wedge resection
|
20 (41)
|
53 (53)
|
34 (50)
|
Patients comprised 156 men and 61 women with ages ranging between 14 and 94 years (median 58 years). The most common diagnosis was primary lung cancer (n = 106), followed by pneumothorax (n = 79), and lung metastases (n = 9). Anatomical pulmonary resection was reported in 110 patients (51%). Operations included 110 anatomical resections, and 107 wedge resections.
Group A (Low-pressure suction group: -5 cm H₂O suction group) comprised 49 patients (25 underwent lobectomy, 4 underwent segmentectomy, 20 wedge resection). Of these patients, three met the exclusion criteria (1 underwent reoperation, 1 required pleurodesis, 1 died). Group B (Intermediate-pressure group: -10 cm H₂O suction group) comprised 100 patients (30 underwent lobectomy, 17 underwent segmentectomy, 53 wedge resection). Of these patients, sixteen met exclusion criteria (7 underwent reoperation, 7 required pleurodesis, 2 required re-drainage). Group C (High-pressure group: -20 cm H₂O suction group) comprised 68 patients (30 underwent lobectomy, 4 underwent segmentectomy, 34 wedge resection). Of these patients, six met exclusion criteria (1 underwent reoperation, 5 required pleurodesis). Patient characteristics were not distributed evenly. There were no statistically significant differences between the groups in terms of sex, age, primary disease, comorbidities, VATS, or surgical procedures. An intraoperative air leak was observed in 87 patients (40%). The number of patients with intraoperative air leak was 22 in group A (45%), 36 in group B (36%), and 29 in group C (43%). A postoperative air leak was observed in 56 patients (26%). The number of patients with postoperative air leak was 8 in group A (16.3%), 24 in group B (24%), and 24 in group C (35%).
Clinical outcomes are presented in Table 2. Assessment of air leaks of patients was performed every morning. The mean duration of air leaks was 0.57 days in group A, 0.78 days in group B, and 1.13 days in group C. In the order of A, B, and C groups, duration of air leaks gradually decreased and significant trend was observed (p = 0.019 by the Jonckheere-Terpstra test). This analysis indicates that chest tube suction pressure was significantly associated with duration of air leaks and low suction pressure promptly improves postoperative air leaks. However, the mean duration of chest tube replacement was 2.12 days in group A, 2.17 days in group B, and 2.35 days in group C and did not significantly differ among the three groups (p = 0.126 by the Jonckheere-Terpstra test). The amount of postoperative day 1 air leak gradually decreased with statistical significance in order of A, B, and C groups (p = 0.033 by the Jonckheere-Terpstra test). The amount of postoperative day 2 air leak did not significantly differ among the three groups (p = 0.520 by the Jonckheere-Terpstra test). The amount of postoperative air leak just after surgery did not significantly differ among the three groups (p = 0.175 by the Jonckheere-Terpstra test). The maximum amount of air leaks during drainage gradually decreased in order of A, B and C groups (p = 0.036 by the Jonckheere-Terpstra test). The mean fluid volume drained before chest tube removal was 304.5 mL in group A, 289.7 mL in group B, and 289.0 mL in group C. Fluid volume drained before chest tube removal did not significantly differ between among three groups (p = 0.986 by the Jonckheere-Terpstra test).
Table 2
Clinical Outcome
|
Low
Pressure
Group A
|
Intermediate
Pressure
Group B
|
High
Pressure
Group C
|
P value (difference between groups)
|
P value
(Jonckheere-Terpstra
test statistics)
|
A vs B
|
A vs C
|
B vs C
|
Duration of air leaks, d
|
0.57 ± 1.60
|
0.78 ± 1.65
|
1.13 ± 1.70
|
0.297
|
0.016
|
0.055
|
0.019
|
Duration of chest tube replacement, d
|
2.12 ± 1.78
|
2.17 ± 1.66
|
2.35 ± 1.67
|
0.730
|
0.380
|
0.380
|
0.126
|
Postoperative air leak, mL/min
|
15.71 ± 48.18
|
6.00 ± 12.87
|
22.50 ± 78.92
|
0.454
|
0.089
|
0.110
|
0.060
|
Postoperative 1st day air leak, mL/min
|
7.76 ± 28.00
|
3.40 ± 8.31
|
8.53 ± 16.41
|
0.353
|
0.035
|
0.041
|
0.033
|
Postoperative 2nd day air leak, mL/min
|
7.59 ± 23.55
|
3.12 ± 8.15
|
8.40 ± 29.51
|
0.980
|
0.980
|
0.980
|
0.520
|
Maximum air leaks, mL/min
|
16.94 ± 49.04
|
7.20 ± 16.09
|
27.06 ± 81.77
|
0.507
|
0.059
|
0.059
|
0.031
|
Fluid volume, mL
|
304.5 ± 356.6
|
289.7 ± 295.0
|
289.0 ± 280.1
|
1.000
|
1.000
|
1.000
|
0.986
|
Postoperative air leak: Postoperative air leak immediately after surgery. Maximum air leaks: the maximum amount of air leaks during drainage. Fluid volume: Fluid volume drained before chest tube removal. |
Clinical outcome in patients who underwent anatomical resection are presented in Table 3. The mean duration of air leaks was 0.90 days in group A, 1.55 days in group B, and 1.94 days in group C. In the order of A, B, and C groups, duration of air leaks gradually decreased with statistical significance (p = 0.010 by the Jonckheere-Terpstra test). The mean duration of chest tube replacement was 2.72 days in group A, 3.10 days in group B, and 3.15 days in group C and did not significantly differ among the three groups (p = 0.141 by the Jonckheere-Terpstra test). The amount of postoperative air leaks just after surgery and postoperative day 1 gradually decreased with statistical significance in order of A, B, and C groups (p = 0.017 and 0.008 by the Jonckheere-Terpstra test). The amount of postoperative day 2 air leak did not significantly differ among the three groups (p = 0.389 by the Jonckheere-Terpstra test). The maximum amount of air leaks during drainage decreased in order of A, B and C groups (p = 0.010 by the Jonckheere-Terpstra test). The mean fluid volume drained before chest tube removal was 424.6 mL in group A, 459.3 mL in group B, and 477.7 mL in group C. Fluid volume drained before chest tube removal did not significantly differ between the three groups (p = 0.288 by the Jonckheere-Terpstra test).
Table 3
Clinical outcomes (anatomical resection)
Clinical Outcome
|
Low
Pressure
Group A
|
Intermediate
Pressure
Group B
|
High
Pressure
Group C
|
P value (difference between groups)
|
P value
(Jonckheere-Terpstra
test statistics)
|
A vs B
|
A vs C
|
B vs C
|
Duration of air leaks, d
|
0.90 ± 2.00
|
1.55 ± 2.13
|
1.94 ± 1.98
|
0.175
|
0.009
|
0.194
|
0.010
|
Duration of chest tube replacement, d
|
2.72 ± 2.03
|
3.10 ± 2.00
|
3.15 ± 1.96
|
0.580
|
0.250
|
0.580
|
0.141
|
Postoperative air leak, mL/min
|
26.20 ± 60.79
|
8.51 ± 12.15
|
42.94 ± 108.36
|
0.467
|
0.061
|
0.061
|
0.017
|
Postoperative 1st day air leak, mL/min
|
12.76 ± 35.75
|
6.81 ± 11.05
|
15.59 ± 20.63
|
0.160
|
0.019
|
0.082
|
0.008
|
Postoperative 2nd day air leak, mL/min
|
8.46 ± 24.77
|
5.22 ± 10.05
|
12.06 ± 35.31
|
0.830
|
0.790
|
0.830
|
0.389
|
Maximum air leaks, mL/min
|
28.28 ± 61.59
|
8.93 ± 12.55
|
51.18 ± 111.02
|
0.647
|
0.043
|
0.020
|
0.010
|
Fluid volume, mL
|
424.6 ± 413.5
|
459.3 ± 349.0
|
477.7 ± 354.8
|
0.940
|
0.940
|
0.940
|
0.288
|
Postoperative air leak: Postoperative air leak immediately after surgery. Maximum air leaks: the maximum amount of air leaks during drainage. Fluid volume: Fluid volume drained before chest tube removal. |
Clinical outcome in patients who underwent wedge resection are presented in Table 4. All category did not significantly differ among the three groups.
Table 4
Clinical outcomes (wedge resection)
Clinical Outcome
|
Low
Pressure
Group A
|
Intermediate
Pressure
Group B
|
High
Pressure
Group C
|
P value (difference between groups)
|
P value
(Jonckheere-Terpstra
test statistics)
|
A vs B
|
A vs C
|
B vs C
|
Duration of air leaks, d
|
0.10 ± 0.45
|
0.09 ± 0.40
|
0.32 ± 0.77
|
0.940
|
0.390
|
0.220
|
0.363
|
Duration of chest tube replacement, d
|
1.25 ± 0.72
|
1.36 ± 0.52
|
1.56 ± 0.75
|
0.300
|
0.120
|
0.300
|
0.079
|
Postoperative air leak, mL/min
|
0.50 ± 2.24
|
3.77 ± 13.19
|
2.06 ± 6.40
|
1.000
|
1.00
|
1.00
|
0.706
|
Postoperative 1st day air leak, mL/min
|
0.50 ± 2.24
|
0.38 ± 1.92
|
1.47 ± 4.36
|
0.830
|
0.820
|
0.450
|
0.596
|
Postoperative 2nd day air leak, mL/min
|
-
|
-
|
-
|
-
|
-
|
-
|
-
|
Maximum air leaks, mL/min
|
0.50 ± 2.24
|
5.66 ± 18.66
|
2.94 ± 7.19
|
0.770
|
0.530
|
0.770
|
0.466
|
Fluid volume, mL
|
130.35 ± 123.86
|
169.88 ± 173.06
|
136.19 ± 119.56
|
1.000
|
1.00
|
1.000
|
1.000
|
Postoperative air leak: Postoperative air leak immediately after surgery. Maximum air leaks: the maximum amount of air leaks during drainage. Fluid volume: Fluid volume drained before chest tube removal. |