Perfusion and ventilation of isolated canine lungs

Pharmacokinetics and toxicity of isolated perfusion of lung with doxorubicin

The treatment of pulmonary metastases from soft tissue sarcomas with chemotherapy has an overall response rate of less than 30%, and the majority of these responses are short lived. It is postulated that increased drug delivery to the pulmonary metastases may improve the outcome of these patients. An isolated perfusion system would have the ability of delivering increased levels of drug to target tissue without the systemic toxic effect of the drug. The purpose of this study was to establish the pharmacokinetics of doxorubicin delivery, lung toxicity, and the ideal dose for clinical application in an in vivo isolated perfusion model. Our results suggest that normothermic isolated perfusion of the lung with doxorubicin using a dose level up to 6 micrograms/ml in the perfusate can be accomplished without histologic lung injury, systemic toxicity, or adverse clinical outcome. Perfusate concentration of greater than 7 micrograms/ml caused significant histologic injury and adverse clinical outcome without systemic toxicity. The technique may be utilized in selective settings to improve treatment in mesenchymal tumors metastatic to the lung.

The isolated perfused lung

The unique nonrespiratory functions of the lungs have become more apparent in recent years. The isolated perfused lung model offers many advantages over other methods for the study of pulmonary metabolism, xenobiotic disposition and the influence of interactions among agents of different physical forms. Detailed descriptions of the experimental preparation are elements in evaluating and comparing data from various sources but these are frequently neglected. A discussion and critique of the following elements are provided in this review in order to elucidate the typical problems one might encounter in evaluating data: perfusate type, perfusion method, construction materials, ventilation method, temperature control, surgical procedure, microbiological contamination and evaluation criteria of the preparation. Examples are given where the IPL method has been applied and suggestions are made for future research efforts.

Isolated lung perfusion with Adriamycin. A preclinical study

Isolated in vivo single-lung perfusion with an Adriamycin-containing whole-blood perfusate was performed in three groups of dogs after establishing adequate controls. The procedure, performed through a left thoracotomy, was followed two weeks later by a contralateral pneumonectomy. Survival following pneumonectomy was used as the ultimate end point in assessing perfusion toxicity. Groups I and II had high mortality rates but provided valuable information concerning perfusion methods, venous drainage techniques, drug dosage schedules, and perfusate flow rates. The group III study consisted of five dogs perfused for 45 minutes at flow rates sufficient to maintain mean pulmonary artery pressure at 12-15 mm Hg. An initial Adriamycin (Adr) dosage of 0.5 micrograms/ml in the plasma perfusate resulted in mean peak Adr lung tissue levels of 3.8 +/- 1.06 micrograms/g. All animals survived right pneumonectomy 19 +/- 4 days later. Three dogs have been killed and histologic examination showed only mild focal pleural and subpleural interstitial fibrosis. Based on these studies it is concluded that isolated single-lung perfusion is a reproducibly safe technique and that a dosage of Adr has been identified which produces no apparent toxity in a large animal model. A clinical trial is currently in progress.

Lung preservation techniques

Some of the barriers to successful lung transplantation include the lack of acceptable methods for ischemic protection and the absence of reliable systems for preservation. The lung response to 60 minutes of warm ischemia basically consists of alveolar-capillary edema and disruption, mitochondria swelling, interstitial hemorrhage, significantly depressed pulmonary function, elevation of pulmonary vascular resistance, and considerable drop in levels of glucose, phospholipids, and adenosine triphosphate. The tolerance to warm ischemia increases to several hours with the use of different systems of ventilatory assistance with or without positive end-expiratory pressure. Several methods of preservation have been attempted: hypothermia, hyperbaria, and hypothermic pulsatile or nonpulsatile perfusion. Hypothermic pulsatile perfusion appears to offer longer periods of protection than the other methods. Longer periods of ischemia and extended preservation may be made possible by advances in the use of drug protection during warm ischemia and the utilization of intracellular colloid or noncolloid solutions for hypothermic storage or hypothermic pulsatile perfusion.