Reconstitution of Blood Supply of the Denuded Bronchial Stump

Autologous Multilayered Fibroblast Sheets Can Reinforce Bronchial Stump in a Rat Model

Bronchopleural fistula is one of the most serious postoperative complications caused by the incomplete healing of a bronchial stump. Fibroblasts play an important role in wound healing by facilitating connective tissue formation and inducing angiogenesis. We developed a method for production of multilayered fibroblast sheets that secreted some growth factors and promoted wound healing. The present study aimed to assess the treatment effect of multilayered fibroblast sheets on bronchial stump healing. In this rat model, left pneumonectomy was performed, and multilayered fibroblast sheets derived from autologous oral mucosal tissues were transplanted to the bronchial stump. The changes in the bronchial stump were examined macroscopically, histologically, and mechanically. The fibroblast sheets promoted the formation of thick connective tissues around the bronchial stump. The formed connective tissues were accompanied by new blood vessels, and fibrosis was observed over time. Then, 7 days after the transplantation of the fibroblast sheets, the bronchial wall became significantly thicker, and the area of the blood vessels for the bronchial wall tissues was significantly larger in the experimental group than in the control group. In addition, the burst pressure in the bronchial stump was significantly higher in the experimental group than in the control group. Bronchial stumps were reinforced by the transplantation of multilayered fibroblast sheets derived from autologous oral mucosal tissues.

Postoperative changes of the free pericardial fat pad for bronchial stump coverage

Background

Bronchopleural fistula (BPF) remains a serious complication after surgery for lung cancer with bronchial resection. A free pericardial fat pad (FPFP) is applied in high-risk cases to reduce BPF frequency. BPF may occur 6 months after surgery. Thus, we evaluated the residual FPFP volume at 6 months after surgery to estimate the residual FPFP ratio and determine the amount of FPFP to be harvested during surgery.

Methods

We retrospectively investigated 40 patients who underwent lobectomy with bronchial stump coverage using FPFP. During surgery, the volume of the harvested FPFP was measured and the FPFP was affixed to the bronchial stump. Further, 6 months after surgery, the residual volume of the installed FPFP was analyzed using a three-dimensional volume analyzer and the residual ratio was calculated. We also evaluated clinicopathological factors influencing the resected FPFP and residual ratio.

Results

The median resected FPFP volume was 11 [3-40] mL. During multivariate analysis, body mass index and surgical approach were found to be significant factors associated with the resected FPFP volume. The median residual FPFP volume was 4.3 (0.4-15.5) mL. The median residual ratio was 0.39 (0.13-0.66). The resected FPFP volume was significantly associated with the residual volume (P<0.001) but not with the residual ratio (P=0.811). No factor was associated with the residual ratio.

Conclusions

In all cases, residual FPFP was confirmed at 6 months after surgery and the residual ratio was 40%. It is necessary to determine the volume of FPFP to be harvested while carefully considering the shrinkage ratio.

Indocyanine green fluorescence/thermography evaluation of intercostal muscle flap vascularization

Background

During anatomical lung resection in high‐risk patients, the bronchial stump is covered with tissue flaps (e.g. pericardial fat tissue and intercostal muscle) to prevent bronchopleural fistula development. This is vital for reliable reinforcement of the bronchial stump. We evaluated the blood supply of the flap using indocyanine green fluorescence (ICG‐FL) and thermography intraoperatively in 27 patients at high risk for developing a bronchopleural fistula.

Methods

Before reinforcing the stump with a flap, the fluorescence agent was intravenously injected and the blood supply was evaluated. The surface temperature of the flap was measured with thermography. The two modalities were then compared.

Results

ICG‐FL intensity and surface temperature on the distal compared to the proximal side of the flap decreased by 32.6 ± 29.4% (P < 0.0001) and 3.5 ± 2.0°C (P < 0.0001), respectively. In patients with a higher ICG‐FL intensity value at the tip than the median, the surface temperature at the tip decreased by 2.7 ± 1.7°C compared to the proximal side. In patients with a lower ICG‐FL value at the tip, the surface temperature decreased by 4.6 ± 1.7°C (P = 0.0574). The bronchial stump reinforced the part of the flap with adequate blood supply; none of the patients developed a bronchopleural fistula.

Conclusions

ICG‐FL confirmed variation in the blood supply of the intercostal muscle flap, even if prepared using the same surgical procedure. Thermography analysis tends to correlate with the fluorescence method, but may be influenced by the state of flap preservation during surgery.

Visualization of bronchial circulation at bronchial anastomotic site using bronchial fluorescein angiography technique

OBJECTIVES

Successful bronchial healing after a bronchoplastic procedure mainly depends on bronchial circulation at the anastomostic site. We developed a bronchial fluorescein angiography (B-FAG) technique for visualizing circulation on the bronchial surface. The technique was evaluated in animals.

METHODS

Fluorescein was used as a contrast agent and an autofluorescence imaging (AFI) bronchoscope as a detector. The left main pulmonary artery (PA) and main bronchus of 10 pigs were isolated. After transection of the left main bronchus and bronchial arteries and re-anastomosis of the bronchus, the pigs were randomly divided into two groups: the PA- group (n = 5), in which the pulmonary artery was transected; and the PA+ group (n = 5), in which the pulmonary artery was preserved. Following intravenous injection of fluorescein, the distal anastomotic site was observed for 30 min with autofluorescence imaging bronchoscopy. Bronchial specimens sampled 2 days after the surgical intervention were histologically evaluated.

RESULTS

In the PA- group, there was no fluorescein enhancement in the distal bronchus throughout the observation time. However, enhancement, which turned the bronchial surface from magenta to bright green, was clearly observed in less than 207 ± 102.5 s in the PA+ group. The enhancement status detected by bronchial fluorescein angiography was related to the extent of tissue damage, as was proven histologically in the acute healing stage.

CONCLUSIONS

Bronchial fluorescein angiography clearly visualized the circulatory status promptly after the anastomosis procedure at the central bronchus. This technique is a potentially practical approach to predict ischaemic airway complications following bronchial anastomosis.

The experimental validation of free fat grafts in thoracic surgery

We evaluated the viability of free fat grafts in the thoracic cavity using 3-month old male swine (n = 2). After left caudal lobectomy, 1-3 g of subcutaneous fat tissue harvested via the thoracotomy site was implanted in the chest cavity. At re-thoracotomy 6 weeks after implantation, all of the implanted fat grafts (n = 15) were found to have closely adhered to the parietal pleura and visceral pleura. There was a significant decrease by ∼30% in the weight of the fat grafts after implantation. Regardless of the weight loss, the implanted fat graft showed normal structuring without scar formation in the central area. Our results may suggest that free fat pads, which weighed up to 3 g, were successfully cultured in the thoracic cavity until the implanted tissues integrated into the surrounding tissues. Therefore, the free fat pad can be used as a biomaterial for some purposes in thoracic surgery.

The pleural and human fibrin glue sandwich: a quick and effective post-pneumonectomy bronchial stump coverage technique

BACKGROUND

Protection of the bronchial stump after pneumonectomy reduces the incidence of bronchopleural fistula. However, which technique provides the most satisfactory results remains open for debate.

MATERIALS AND METHODS

We describe a study in which a bronchial stump coverage technique was performed using 2 layers of human fibrin glue (Tissucol; Baxter, Deerfield, IL USA) with an interposed patch of parietal pleura. From July 2005 to June 2007, this technique was used in 31 consecutive patients after standard pneumonectomy by a single surgeon.

RESULTS

None of the patients developed early or late bronchopleural fistula, and no clinical adverse reaction was recorded. During the same period, alternative stump coverage techniques were used by different surgeons in 71 pneumonectomies. In this group, the rate of fistula was 6% (4 patients).

CONCLUSION

These preliminary data demonstrate the feasibility of the technique and suggest that it is at least equivalent to the other type of flaps used. The main advantages of this technique are the restoration of the natural separation between the mediastinum and pleural cavities, as well as the reduced operating time (duration 5 minutes).