Long term effect of the systemic glutamine administration in rats on the alveolar air leak and parenchymal healing appearing in the postoperative period

Purpose: Alveolar air leaks, which is one of the most common complications that appears in the postoperative period with respect to the thoracic surgery, is one of the most important reasons increasing the length of hospitalization in the postoperative period considering the clinical trials. Air leaks in the parenchyma of lung can be prevented with efficient wound healing. Metabolic responses to injury arise due to the nitrogen loss in the body, whether the injury occurred after the accident surgery or elective surgery. This loss is mostly observed in the skeletal muscle, and constitutes 50-70% of the amino acid nitrogen transported to the visceral tissues by alanine and glutamine. Glutamine, on the other hand, is one of the most common amino acid in the circulation system, it is mostly produced in the skeletal muscle and in the lungs following the said muscles; it also constitutes 30-35% of the plasma amino acid nitrogen. The positive effects of replacing the glutamine decreased after the trauma or surgery such as wound healing, boosting the immune system and intestinal permeability have been shown in various studies. We aimed at conducting a research regarding the long term effects of systemic glutamine administration on healing of the lung parenchyma and preventing the alveolar air leaks in our study.Method: The trial protocol has been approved by the Ethics Committee of the Medical Faculty of Dokuz Eylul University (Protocol no.: 18/2012). Nineteen young adult female Wistar albino rats from the same colony which weigh averagely 194 gr were used in our study. The rats were divided in three different groups. Only right thoracotomy was used on the rats in the first group, and they were not exposed to any parenchymal damage. Following the right thoracotomy, parenchyma of the rats in the second and third groups was damaged.Saline was administered to first two groups via intraperitoneal injection (i.p) for 12 days in total -2 days in the preoperative and 10 days in the postoperative period-, on the other hand, glutamine (GLN) was administered to the third group intraperitoneally (i.p) for 12 days in total -2 days in the preoperative and 10 days in the postoperative period.Ether was used as an anesthetic. Intercostal blockade was performed with bupivacain administered as analgesic. Median sternotomy was carried out on the rats sacrificed in the 11th day of postoperative period, and then trachea was removed along with all lung tissues. Cannula was placed in the trachea and air leaks which appear after compressed air was applied through the lungs were observed. Pressure values were measured for leaks. Tissues were taken from the area where the parenchyma was damaged; inflammation and mature collagen was analyzed histopathologically. Using the image analysis program, the collagens in tissues were evaluated morphometrically.Findings: There was no significant difference in terms of evaluating the inflammation and postoperative adhesion among Sham, control and GLN groups. Significant differences were detected among three groups in terms of evaluating the pressure which causes air leak. On the other hand, a statistical difference was only observed between the sham and GLN groups considering the evaluation of mature collagen amount.Results: The most significant difference among our groups was found in the pressure values causing air leak. Especially the statistical significance observed between the GLN and control groups indicates the effect of systemic GLN administration on healing. The fact that there is not any significant difference regarding the collagen amount among groups, and the fact that the difference was only observed in favor of sham group considering the sham and GLN groups may cause us to think that the increase in the mature collagen amount has no effect on the healing of air leaks.Key Words: Air Leak, Parenchymal Damage, Glutamine, Collagen