Experimental study of extracorporeal lung resection in dogs: ex situ sleeve resection and autotransplantation of the pulmonary lobe after extended pneumonectomy for central lung cancer

Porcine pulmonary auto-transplantation for ex vivo therapy as a model for new treatment strategies

OBJECTIVES

Lung auto-transplantation is the surgical key step in experiments involving ex vivo therapy of severe or end-stage lung diseases. Ex vivo therapy has become a clinical reality because of systems such as the Organ Care System (OCS) Lung, which is the only commercially available portable lung perfusion system. However, survival experiments involving porcine lung auto-transplantation pose special surgical and anaesthesiological challenges. This current study was designed to describe the development of surgical techniques and aneasthesiological management strategies that facilitate lung auto-transplantation survival surgery including a follow-up period of 4 days.

METHODS

Left pneumonectomy was performed in 12 Mini-Lewe miniature pigs. After ex vivo treatment of the harvested lungs within the OCS Lung for 2 h, the lungs were retransplanted into the same animal (auto-transplantation). Four animals were used to develop the optimal techniques and establish an experimental protocol. According to the final protocol, eight additional animals were operated. The follow-up period was 4 days.

RESULTS

There were four severe intraoperative surgical complications [anatomical variant of the superior vena cava (two times), a complication related to the bronchial anastomosis and a complication related to the pulmonary arterial anastomosis]. The major postoperative problems were hyperkalaemia, prolonged recovery from anaesthesia and pulmonary oedema after reperfusion. Establishment of the surgical technique showed that using a pericardial tube to facilitate the anastomosis of the thin left superior pulmonary vein should be considered to prevent thrombosis. However, routine use of the patch technique to construct venous and arterial anastomoses is not necessary. Furthermore, traction on the venous anastomoses can be avoided by performing the bronchial anastomosis first.

CONCLUSIONS

Lung auto-transplantation is a feasible experimental model for ex vivo therapy of lung diseases and is applicable for experimental questions concerning human lung transplantation.

[Ex situ tracheobronchoplastic operations using the organ care system]

First clinical experiences with the organ care system (OCS) in lung transplantation showed that this device allows perfusion and ventilation of the lungs under practically physiological conditions. Some pulmonary pathologies necessitate ex situ operations, e.g. to avoid pneumonectomy. The objective of this work was to investigate the feasibility of ex situ pulmonary surgery within the OCS.In the first procedure a large tracheobronchial leakage was covered with a pericardial patch. The procedure was authorized by the local committee of animal welfare. In the second surgery a replacement of the distal trachea using an aortic graft was performed after removal of the heart-lung segment from a pig from the slaughterhouse. The postoperative ventilation of both lungs was free of problems. The mean pressure of the pulmonary artery remained steady during the whole experiment. The setup to prevent lung edema was basically successful.Performing thoracic surgery with the OCS is feasible; however, this approach is reserved for very special indications. Further investigations to optimize technical details of the OCS setup for this purpose are necessary.

Ethyl 2-cyanoacrylate tissue adhesive in partial lobectomy in rats

OBJECTIVE

To determine the efficacy of ethyl 2-cyanoacrylate adhesive in repairing the lung parenchyma after partial lobectomy in rats, in terms of hemostasis/aerostasis, scarring, and surgical time.

METHODS

The study involved 30 Wistar rats, randomly divided into five groups (one control group and four study groups). In the study groups, the lung parenchyma was repaired with either cyanoacrylate adhesive or surgical suture following resection of a small or large fragment (25% or 50%, respectively) of the left caudal lung lobe.

RESULTS

Surgical time and hemostasis time were shorter in the two groups treated with the adhesive than in the two submitted to suture. There were no significant differences among the groups regarding specific lung compliance. Adherences and inflammatory reactions were more severe in the groups submitted to suture.

CONCLUSIONS

In this study, the use of cyanoacrylate adhesive helped reduce the surgical time and the intensity of inflammatory reactions, as well as preserving lung compliance. Cyanoacrylate adhesives should be considered an option for lung parenchyma repair, decreasing the risk of complications after partial lobectomy in humans.

The effects of anesthetic preconditioning with sevoflurane in an experimental lung autotransplant model in pigs

BACKGROUND

Ischemia-reperfusion lung injury is doubly important in thoracic surgery because of the associated ventilation damage to 1 lung. In this study we evaluated the cytoprotective effects of sevoflurane in a pulmonary autotransplant model in pigs.

METHODS

Twenty Large White pigs undergoing pneumonectomy plus lung autotransplant were divided into 2 10-member groups on the basis of the anesthetic received (propofol or sevoflurane). Proinflammatory mediators, oxidative stress, nitric oxide metabolism, and hemodynamic and blood variables were measured at 5 different time points.

RESULTS

There was an increase of oxidative stress markers and proinflammatory mediators in the propofol group, whereas the hemodynamic variables were similar in both groups.

CONCLUSIONS

We demonstrated that sevoflurane decreased the inflammatory response and oxidative stress in a live ischemia-reperfusion lung model.

Experimental Swine lung autotransplant model to study lung ischemia-reperfusion injury

INTRODUCTION

Ischemia-reperfusion (IR) lung injury has been investigated extensively on clinical and experimental models of cold ischemia. However, relatively few studies examine the detailed biochemical changes occurring during normothermic (warm) IR. The objective of this work was to establish an experimental lung autotransplant model to be carried out on pigs in order to study the early stages of normothermic lung IR. ANIMALS Y METHODS: Six Large-White pigs underwent a lung autotransplant which entailed left pneumonectomy, ex situ cranial lobectomy, caudal lobe reimplantation and its reperfusion for 30 min. Throughout the procedure, several parameters were measured in order to identify hemodynamic, gasometric and biochemical changes. Non-parametric statistical analyses were used to compare differences between periods.

RESULTS

After ischemia, a significant increase (P < 0.05) in lipid peroxidation metabolites, proinflammatory cytokines and chemokines (TNF-α, IL-1β y MCP-1), neutrophil activation, inducible nitric oxide synthase activity and protein-kinase MAPK p38 levels were observed in lung tissue. However, constitutive nitric oxide synthase activity in lung tissue and carbon monoxide plasma levels were decrease. The same held true throughout the reperfusion period, when an increase in the constitutive heme-oxygenase activity was also shown.

CONCLUSIONS

An experimental model of normothermic lung IR injury is presented and detailed changes in hemodynamic, gasometric and biochemical parameters are shown. Both the model and the studied parameters may be clinically useful in future investigations testing new therapies to prevent normothermic IR induced lung injury.