Intraoperative control of air leak using a sutureless free pericardial fat pad covering method in lung cancer resection

Abstract Here, we introduce a new method for intraoperative control of air leak using a free pericardial fat pad covering to lung damage with sutureless fixation. We covered the damaged lung tissue with a free pericardial fat pad with a polyglycol acid sheet and fibrin glue fixation. This method provides a good air leak controlling effect with the use of a free pericardial fat pad and relatively short operative time with sutureless fixation.

Damage of lung parenchyma during surgery represents the most common cause of air leak after pulmonary resection, 1 and intraoperative damage repairing techniques are important to reduce postoperative air leak. A variety of techniques have been adopted; however, there are several problems. First, lung suture techniques are difficult if there is damage near the hilum or damage to a fragile lung (e.g., chronic obstructive pulmonary disease [COPD], interstitial pneumonia [IP]). Second, it is difficult to cover complexed shaped damage with the sheet-type sealants. Third, suturing techniques require technical skill and longer operative time especially in video-assisted thoracoscopic surgery (VATS). To overcome these problems, we have introduced a new method which uses free pericardial fat pads (FPFP) to cover damage to the lung parenchyma without suturing (sutureless fat pad method: SFP method). The purpose of this study was to investigate the clinical outcomes of patients who were treated with this new method.

Patients
This study was approved by the ethics review board of Japanese Red Cross Society Nagano hospital, Nagano, Japan (approval no.: R-099), and the requirement for informed patient consent was waived.
In total, 78 patients underwent anatomic lung resection for the treatment of primary lung cancer at Japanese Red Cross Society Nagano hospital between February 2022 and March 2023. We divided these patients into four groups based on the type of intraoperative lung parenchymal damage (also shown in Figure S1): Type 1, incomplete staple line (intraoperative air leak from staple line); Type 2, delamination; and Type 3, laceration.
We selected 22 type 2 or 3 patients in this study as they were supposed to be at a greater risk of PAL. All type 2 and 3 patients had an air leak in the intraoperative water sealing test. To maintain uniformity, one surgeon (S.K.) operated on all patients enrolled in this study, and patients that were operated on by other surgeons were excluded ( Figure S2).

Techniques and surgical procedure
After lung resection was completed, the damage of the lung parenchyma was assessed as previously described (Type 0, no damage; Type 1, incomplete staple line; Type 2, delamination; Type 3, laceration). When the damage was type 2 or 3, which is supposed to cause a greater risk of air leak, a sufficient amount of FPFP was harvested to cover the damage using LigaSure Maryland (Medtronic, Covidien Products). The harvested FPFP was fixed to the damaged area by applying fibrin-glue (Bolheal, KM Biologics Co., Ltd.) (Figure 1a-c). The FPFP was attached without pleura side of FPFP, because it is easier to thickly fix to the damaged area. Then, polyglycol acid (PGA) sheet (Neoveil, Gunze Ltd.) was used to cover the FPFP and the damaged lung parenchyma (Figure 1d). After that, we applied fibrin glue again to strength the fixation ( Figure 1e). All patients had one chest tube placed apically.

Postoperative management
Chest tubes were placed postoperatively under negative pressure suction of 10 cmH 2 O until the patients were moved to the intensive care unit (ICU) from the operative room. After the patient was admitted to ICU the suction pressure was reduced to water seal. The chest tubes were removed on the next day following the air leak disappeared date with previous roentgenogram check.

Assessment
Data were collected on age, gender, smoking habits, history of COPD/IP/combined fibrosis and emphysema (CPFE), type of surgery, pulmonary pathology, time for our method (time for FPFP harvesting + FPFP fixing), and duration of air leaks. Postoperative CT was checked to evaluate the residual FPFP and its position. The postoperative CT includes both CT scans performed during postoperative hospitalization and those performed in the outpatient clinic.

RESULTS
The characteristics of 22 patients and results of our FPFP damage covered without the suturing method are demonstrated in

DISCUSSION
A range of methods for the control of intraoperative air leaks have been previously reported, such as suturing, stapling, and covering with sheet type sealant products (oxidized regenerated cellulose [ORC] mesh, PGA sheet, or collagen sponge). [7][8][9] There are problems associated with these methods which include: (1) difficulty in suturing or stapling damaged lung near the hilum, or a fragile lung (e.g., COPD, IP/CPFE). (2) It is difficult for sheet type sealant products to cover the complex shaped surface of the damaged surface of the lung. (3) The suturing method is lengthy and is considered an advanced technique, especially in VATS.
Our SFP methods overcame all of the problems described above. In our study, the median air leak duration was one day (25-75 percentiles, 0-2) and PAL occurred in only one CPFE patient. Also, the median time for our method was 169 s (25-75 percentiles, 141-262), which is relatively short. The results suggest that our lung parenchymal damage repairing method is effective and efficient.
Similar to our method, there have been some reports which have noted the efficacy of using isolated fat as a sealant. These reports have also revealed the greater effect of fat sealant than the PGA sheet + fibrin glue methods. [10][11][12] Shintani et al. reported using the subcutaneous fat pad method. 10 Ikeda et al. and Kameyama et al. reported using the FPFP method. 11,12 However, all these methods sutured fat materials to the lung damaged area, and it is necessary to deal with the problems which might arise as described in (1) and (3) above. To reveal the superiority of our method to the fat suturing methods in (3), we retrospectively investigated the time for FPFP suturing (n = 2, VATS) and lung suturing (n = 5, VATS) that had taken place before this study started (June 2020 to December 2021) as a reference data and compared this to the time for our method. The median time for our method was 167 s (25-75 percentiles, 137-279) as mentioned above; FPFP suturing was 812 (693-932), and lung suturing 421 (280-491) ( Table S1). The time for our method was obviously shorter than using suturing methods.
Similar to our method, Yoshimura et al. reported using the pedicled pericardial fat pad method with fibrin glue fixation to the lung. 13 Harvesting pedicled pericardial fat pad requires more technical skill and operative time than harvesting FPFPs, and usually, the amount of harvested fat become smaller than FPFPs, especially when the damaged lung is far from the pericardium. The amount of harvested FPFPs positively affects air leak prevention; 11 therefore, longer air leak duration (3.6 ± 3.4 days, n = 15) in that study might have been caused by a smaller amount of FPFPs compared with our study.
The risk of loss of the FPFPs in the postoperative period is one of the concerns of the nonsuturing method in this study. In our study, postoperative CT was checked in 13 patients and 10 (76.9%) patients had residual FPFPs in the same position as the fat fixed in the operation. These results suggest the satisfactory preservation of FPFPs in our method.
In conclusion, in this study we have introduced an effective and efficient method for the control of intraoperative air leak using sutureless fixation of FPFPs for lung damage.