Lateral position with the remaining lung uppermost improves matching of pulmonary ventilation and perfusion in pneumonectomized pigs

Technique and perioperative management of left pneumonectomy in neonatal piglets

BACKGROUND

Although commonly performed in adult swine, unilateral pneumonectomy in piglets requires significant modifications in the surgical approach and perioperative care because of their smaller size and limited physiological reserve.

METHODS

Nineteen neonatal piglets underwent a left pneumonectomy. They were allowed 5-7 d of preoperative acclimation and nutritional optimization. Preoperative weight gain and laboratory values were obtained before the time of surgery. A "ventro-cranial" approach is adopted where components of the pulmonary hilum were sequentially identified and ligated, starting from the most ventral and cranial structure, the superior pulmonary vein. The principle of gentle ventilation was followed throughout the entire operation.

RESULTS

The median age of the piglets at the time of surgery was 12 (10-12) d. The median preoperative weight gain and albumin level were 20% (16-26%) and 2.3 (2.1-2.4) g/dL, respectively. The median operative time was 59 (50-70) min. Five of the first nine piglets died from complications, two from poor preoperative nutritional optimization (both with <10% weight gain and 2 g/dL for albumin), one from an intubation complication, one from intra-operative bleeding, and one in the postoperative period from a ruptured bulla. No mortality occurred for the next 10 cases.

CONCLUSIONS

Successful outcomes for unilateral pneumonectomy in piglets require special attention to preoperative nutritional optimization, gentle ventilation, and meticulous surgical dissection. Preoperative weight gain and albumin levels should be used to identify appropriate surgical candidates. The "ventro-cranial" approach allows for a technically straightforward completion of the procedure.

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.

Positive end-expiratory pressure attenuates positional effect after thoracotomy

CONTEXT:

Thoracotomy is a common procedure. However, thoracotomy leads to lung atelectasis and deteriorates pulmonary gas exchange in operated side. Therefore, different positions with operated side lowermost or uppermost may lead to different gas exchange after thoracotomy. Besides, PEEP (positive end-expiratory pressure) influence lung atelectasis and should influence gas exchange.

AIMS:

The purpose of this study was to determine the physiological changes in different positions after thoracotomy. In addition, we also studied the influence of PEEP to positional effects after thoracotomy.

MATERIALS AND METHODS:

There were eight pigs in each group. Group I received left thoracotomy with zero end-expiratory pressure (ZEEP), and group II with PEEP; group III received right thoracotomy with ZEEP and group IV with PEEP. We changed positions to supine, LLD (left lateral decubitus) and RLD (right lateral decubitus) in random order after thoracotomy.

RESULTS:

PaO₂ was decreased after thoracotomy and higher in RLD after left thoracotomy and in LLD after right thoracotomy. PaO₂ in groups II and IV was higher than in groups I and III if with the same position. In group I and III, PaCO₂ was increased after thoracotomy and was higher in LLD after left thoracotomy and in RLD after right thoracotomy. In groups II and IV, there were no PaCO₂ changes in different positions after thoracotomy. Lung compliance (C_rs) was decreased after thoracotomy in groups I and III and highest in RLD after left thoracotomy and in LLD after right thoracotomy. In groups II and IV, there were no changes in C_rs regardless of the different positions.

CONCLUSION:

There were significant changes with regards to pulmonary gas exchange, hemodynamics and C_rs after thoracotomy. The best position was non-operated lung lowermost Applying PEEP attenuates the positional effects.