CT-based diagnosis of bronchial stenosis after lung transplantation

Introduction: Among all types of transplant complications, that related to airway anastomosis, such as stenosis is still uncertain¹². Starting by the difficulty in diagnosis, such as the low precision of bronchoscopy, high cost and invasive test. This article purpose a precise and non-invasive diagnostic method of bronchial stenosis after lung transplantation based on three measures got from a reconstruction of thorax computerized tomography (CT) using a software called TeraRecon. Objective: The anastomosis index (AI), ratio of the area of the bronchial cross-section at the site of the anastomosis to the arithmetic mean of the cross-sectional areas 5 mm upstream and 5 mm downstream, obtained from reconstruction of a thorax CT has direct correlation with the bronchoscopic and clinical diagnosis of bronchial stenosis. Methods: Were obtained all cases of clinical and bronchoscopic diagnosed bronchial stenosis after lung  transplantation at Heart Institute of University of São Paulo, between 2003 and 2016 (n=8). Another 8 patients, without any signs of stenosis, were selected to the control group. After that, the closest CT from the diagnostic was obtained and reconstructed using the software Terarecon, which is capable to find the exact area of any point of a cylindrical structure chosen by the operator. Then, three areas were obtained: 5mm before, at the anastomosis and 5mm after. Were calculated the Anastomosis Index (AI), which is the ratio between the area of anastomosis, and the arithmetic average of the areas 5mm before and 5mm after the anastomosis. After that, the data was confronted to variation of best FEV1 from transplantation to chosen CT and the FEV1 closest to the chosen CT. Results: As expected, in patients without bronchial stenosis, the area of the bronchi cross- section decreases linearly as it moves from proximal to distal in the bronchial tree, the AI in these cases tends to 1. Whereas, when there is no decay linear, that is, there is bronchial stenosis at the anastomosis, the AI was less than 1. There was a significant difference between AI in stenosis group (n=8, M = 0.387, SD = 0.151) and control group (n=8, M = 0.850, SD = 0.091). t(16)= -7.893 p < 0.001. This findings were supported by mean reduction of FEV1 in 17.71% and median 19.81% on stenosis group and mean reduction of 5.45%, and median 5.35% on control group. Besides that, the values undergone in a t-test, which returned a t-value = 2.879 with a p-value = 0.0129. The result is significant at p < 0.05. Conclusion: The Anastomosis Index can be useful in diagnosis of bronchial stenosis after lung transplantation, it is harmless and subsequently may help as a basis for new studies involving treatments. It is worth mentioning that is also a rational use of resources, since lower costs are generated by the CT analysis than performing a bronchoscopy, besides not requiring hospitalization and sedation, taking into account that these patients presents greater risks by the immunosuppression and other comorbidities.Supplemental Material Figure 1. Shown in red, the three points of measure used to calculate the Anastomosis index Figure 2: Boxplot showing distribuition of Anastomosis Index in control and stenosis group Figure 3: Boxplot showing the diferences in percentages between FEV1 in stenosis and control group References Margreiter R. History of lung and heart-lung transplantation, with special emphasis on German-speaking countries. Transplant Proc. 2016;48(8):2779-81. Hardy The first lung transplant in man (1963) and the first heart transplant in man (1964). Transplant Proc. 1999;31:25-9. Derom F, Barbier F, Ringoir S, Versieck J, Rolly G, Berzsenyi G, Vermeire P, Vrints L.Ten-month survival after lung homotransplantation in man. J Thorac Cardiovasc Surg. 1971;61(6):835-46. Awori Hayanga JW, Aboagye JK, Shigemura N, Hayanga HK, Murphy E, Khaghani A,D;Cunha J. Airway complications after lung transplantation: Contemporary survival and outcomes. J Heart Lung Transplant. 2016;35(10):1206-11. Fonseca HV, Iuamoto LR, Minamoto H, Abdalla LG, Fernandes LM, Camargo PC, Samano MN, Pêgo-Fernandes PM. Stents for bronchial stenosis after lung transplantation: should they be removed? Transplant Proc. 2015;47(4):1029-32. Kraft BD, Suliman HB, Colman EC, Mahmood K, Hartwig MG, Piantadosi CA, Shofer SL. Hypoxic gene expression of donor bronchi linked to airway complications after lung transplantation. Am J Respir Crit Care Med. 2016;193(5):552-60

A comparison of two bronchial anastomotic techniques in lung transplantation by means of tridimensional tomographic analysis:: the bronchial anastomotic index

Background: The objective of this study was to compare two different techniques of bronchial anastomosis in lungtransplant, assessing differences in bronchial narrowing post-surgery.Methods: The surgical team at our center switched between simple stitches to continuous suture to anastomose the anterior bronchial wall in lung transplant procedures. CT scans of the patients obtained three months after the surgery were subject to analysis. The cross section area of the airway at the point of anastomosis was compared with an average of the cross sections of the bronchus 5mm proximal and distal to the point of anastomosis, determining the anastomotic index (AI). Data of 32 bronchi anastomosed with continuous suture from 19 patients were compared to data of 37 bronchi anastomosedwith interrupted suture from 20 patients.Results: Multivariate analysis showed significant difference in bronchial diameter reduction between patients subjected to the two techniques, with no difference between the two sides in any of the groups. The bronchi anastomosed with simple stitches had a significantly larger AI than those anastomosed with running suture (mean AI 0.98 vs 0.82, p < 0.001). A significantly larger number of bronchi subjected to this method had their AI greater than 1 comparing to bronchi anastomosed with a running suture (13 vs 1, p < 0.001).Discussion: The use of simple stitches to join the anterior bronchial wall surpasses a running suture in terms of bronchial narrowing. The interrupted suture technique seems to result in a mechanical widening at the point of anastomosis