Pulmonary mechanics and surfactant measurement in canine lungs following reimplantation

Abstract

The left lung was reimplanted in 18 dogs. Failure of the venous anastomosis was the chief technical complication. Thirteen dogs survived until killed from eight days to 15 weeks after the operation. There was an immediate fall in total pulmonary compliance following the procedure, then a return to near normal within eight days. Surfactant and lung stability were normal. In each case there was a marked reduction in the gas volume of the reimplanted lung.The chief problem that prevents the use of pulmonary transplantation as a therapeutic measure is that of graft rejection. However, problems concerning operative technique and the physiological function of the transplanted lung also remain unsolved. These may be studied by pulmonary reimplantation in animals.Successful reimplantation of a dog's lung was first reported by Mdtras in 1950, and although reimplantation has been extensively studied since, an unacceptably high mortality occurs in most series (Hardy, Eraslan, and Webb, 1964;Guilmet, Brunet, Krakora, Leiva, and Weiss, 1965;Mouritzen, Boye, Lyager, and Ottosen, 1967). Prolonged survival of animals with a single reimplanted lung after contralateral pneumonectomy (Hill and Shaw, 1968) and with bilaterally reimplanted lungs (Fafber, Pedreira, Pevsner, and Beattie, 1965) demonstrates that considerable pulmonary function may be regained. However, it is clear from these and other studies that there is impairment of function, especially in the postoperative period, after which improvement may occur. The reasons for these changes are poorly understood. This study was carried out to investigate the problems of pulmonary reimplantation with particular reference to pulmonary mechanics. METHODSOPERATIVE TECHNIQUE Eighteen mongrel dogs, weighing from 8-7 to 23-5 kg., were anaesthetized with intravenous methahexitone, then maintained on nitrous oxide and oxygen via an endotracheal tube. Muscle relaxation was obtained with intravenous gallamine, and the animals were ventilated with a Manley positive pressure ventilator, 20 ml./kg. body weight per breath, at 15 breaths per minute. Compliance was then measured as described below. Using sterile techniques, thoracotomy was performed through the fifth left intercostal space. The left pulmonary artery, left main bronchus, and an intrapericardial cuff of the left atrium, together with the left pulmonary veins, were dissected free from connective tissue. The pulmonary artery was divided at the midpoint, the bronchus was transected near the take-off of the upper lobe bronchus, and a close-fitting cork was placed in the bronchus to prevent air leakage and to maintain ventilation. The cuff of left atrium with attached pulmonary veins was then excised and the lung was removed from the chest.The pulmonary artery of the isolated lung was immediately perfused with heparinized low molecular weight dextran at 5°C. (3,000 I.U./500 ml.) at a pressure of 40 cm. H20 until the perfusate ran clear. Pressure volume studies on the isolated lung were then performed as described below. The lung wa...