Timothy S. Hall

Assessment of lungs rejected for transplantation and implications for donor selection

Present criteria for donor-lung selection exclude more than 85% of lungs. We aimed to establish if potentially suitable lungs are rejected for transplantation. We obtained 29 pairs of rejected lungs and assessed them by physiological, microbiological, and histological methods. Most donor lungs had no or mild pulmonary oedema (24/29 [83%]), intact alveolar fluid clearance (17/23 [74%]), and normal or mildly abnormal histological findings (18/29 [62%]). When all factors were considered, including microbiological and non-lung donor factors, 12 (41%) of 29 pairs of rejected lungs would have been potentially suitable for transplantation. Our findings emphasise the urgent need for prospective scientific assessment of selection of donors for lung transplantation.

Hemorrhage related reexploration following open heart surgery: the impact of pre-operative and post-operative coagulation testing.

PURPOSE Our objective was to determine the association of pre-operative and post-operative coagulation testing abnormalities with the cause of post-operative bleeding requiring re-exploration following cardiac surgery. METHODS Retrospective chart review of post-operative bleeding and the incidence of re-exploration for hemorrhage in 2263 adult patients undergoing elective and emergency open heart surgery which included coronary artery bypass, valvular, and combined valve coronary procedures. RESULTS Eighty-two patients (3.6%) required re-exploration. Sixty-six percent had surgical bleeding; the remaining 34% were coagulopathic (no surgical site found). The pre-operative PT and ACT were significantly elevated in coagulopathic patients (P<0.005). Post-operative ACT, PT, and APTT were increased and fibrinogen levels were decreased in coagulopathic patients (P<0.05). CONCLUSIONS Pre-operative testing (ACT, PT) weakly correlated with post-operative coagulopathy. Post-operative coagulation abnormalities were identified with high risk ratios and good diagnostic accuracy when using testing cut-off values to assist in surgical decision making.

Giant Solitary Fibrous Tumor of the Pleura

Solitary fibrous tumors of the pleura are rare. Approximately 600 cases have been described in the literature. We report a case of a young man with a giant solitary fibrous tumor of the pleura that filled his entire left hemithorax and anterior mediastinum and extended into the right side of his chest. The diagnostic modalities employed, the operation, and the postoperative management resulting in complete resection of the tumor and full lung reexpansion are described.

Thoracic organ donor characteristics associated with successful lung procurement.

Purpose: A shortage of suitable donors is the major impediment to clinical lung transplantation. The rate of lung recovery from potential donors is lower than that for other organs. The purpose of this study was to evaluate what factors could be modified to improve the rate of cadaver lung recovery. 
Methods: We performed a retrospective review of records from all thoracic organ donors procured by the California Transplant Donor Network between 1 January 1995 and 31 May 1997 (251 donors) to determine which donor management factors were associated with an increased likelihood of successful lung procurement. 
Results: There were 88 lung donors (L) and 163 donors from which hearts but no lungs were procured (H). Longer time to donor network referral was associated with a reduced chance for successful lung procurement. Donor age, cause of death, and time of admission were not important factors. Most donors in this study had an acceptable A‐a gradient at admission to the hospital but lung function deteriorated in group H. Corticosteroid usage and initially clear breath sounds were independent predictors of successful procurement by multivariate analysis. 
Conclusions: Early contact with the donor referral network, and corticosteroids may help to improve the lung procurement rate from potential donors.

Measurement of fibroblast proliferative activity in bronchoalveolar lavage fluid in the analysis of obliterative bronchiolitis among lung transplant recipients.

BACKGROUND Bronchiolitis obliterans occurs in 30% to 80% of lung-transplant recipients and is a direct cause of death in more than 40% of patients with this complication. This study assessed the potential utility of measuring fibroblast-proliferative activity in bronchoalveolar lavage fluid from lung-transplant recipients to better understand the pathogenesis of this process. METHODS The capacity of bronchoalveolar lavage fluid obtained from transplant recipients, during routine surveillance bronchoscopy, to stimulate the proliferation of human lung fibroblasts in vitro was assessed retrospectively and compared to that of control subjects. For each recipient, a correlation was made between the fibroblast-proliferative activity in serial lavage samples over time and the other modalities employed for detecting post-transplant complications including spirometry, transbronchial lung biopsy, and high-resolution computed tomography. RESULTS There was a significant difference in fibroblast-proliferative activity between volunteer and transplant recipient groups (p = 0.002). Further, for each transplant recipient, the decline in the forced expired flow rate between 25% and 75% of expired volume (FEF(25%-75%)) was correlated with the mean fibroblast-proliferative activity during the period of this study (r = 0.83; p = 0.04). CONCLUSIONS A sustained increase in fibroblast-proliferative activity in lavage supernatant precedes both histologic and physiologic evidence of bronchiolitis obliterans. Relative to an increase in fibroblast-proliferative activity or abnormalities in FEF25%-75%, a decrease in forced expiratory volume in 1 second is a late finding.

Management Strategies for Complex Bronchopleural Fistula

The management of complex bronchopleural fistula remains a major therapeutic challenge for the thoracic surgeon. Although the incidence of bronchopleural fistula following lung resection has decreased in recent years to 1% to 2%, when it occurs, it is associated with significant morbidity and mortality. Using illustrative cases, the epidemiology and pathophysiology of bronchopleural fistula are reviewed and operative strategies are discussed. Algorithms for the diagnosis and treatment are suggested on the basis of cases described in the literature. The best way to prevent a fistula is to rigorously follow the surgical techniques described, with minimal devascularization of the bronchus and prophylactic coverage of the stump in high-risk patients. Successful management of a fistula is combined with treatment of the associated empyema cavity. Definitive repair should be accomplished expeditiously, minimizing the number of procedures performed. When treatment is protracted, secondary complications are more likely and survival is adversely affected. The first step should be control of active infection and adequate drainage of the hemithorax, followed by timely repair of the bronchopleural fistula when possible and reinforcement of the stump with vascularized tissue. If a residual cavity is present it must also be obliterated with a pedicled muscle flap.

A comparison of rat tracheal transplant models: implantation verses anastomotic techniques for the study of airway rejection.

Background. In rodent models, investigators have transplanted donor tracheas into a recipient rat’s abdomen or s.c. tissue to study airway rejection. We describe a modification of this model, which provides improved histology to study the airway injury related to obliterative bronchiolitis. Methods. The standard technique of implanting the donor trachea was compared to a model in which a tracheal Y graft was created by anastomosis of the donor trachea to the recipient airway. Syngeneic and allogeneic tracheal grafts (Lewis and Brown Norway rats) were harvested at 2 and 4 weeks using each model (eight groups). Results. Gross patency at the tracheal anastomosis grafts was 100%. All donor tracheas, which were implanted without an anastomosis, were occluded with mucus (syngeneic) or granulation tissue (allogeneic). Syngeneic implant grafts demonstrated significantly less lumenal granulation tissue 35.3%±32 than the allograft implant group (95.3%±9.2, P =0.0005 at 4 weeks). The anastomotic allograft group demonstrated significantly less lumenal granulation tissue 48.3%±23.7 when compared with the implanted allograft group (P =0.003). The implanted allograft demonstrated a severe loss of epithelial integrity by 2 weeks (16.7%±38), which progressed to complete loss by 4 weeks (P =0.0001 and P =0.0001 vs. native). This loss was significantly more than that of the anastomotic group at 2 weeks (89.5%±13, P =0.004) and 4 weeks (88.3±29, P =0.005). Conclusions. The rat tracheal allograft anastomosed to the recipient airway demonstrated less lumenal granulation tissue obstruction and better preservation of epithelial integrity than an implant allograft, suggesting that an open airway improves assessment of transplant-related changes associated with rejection.

Transfusion for coagulopathy after heart surgery: efficacy of laboratory studies.

Limited information exists regarding transfusions specifically for coagulopathy following cardiac surgery and the value of pre- and postoperative coagulation tests. Procedures (86% coronary bypass, 7.5% valve, and 6.5% combined valve and bypass) on 478 patients were reviewed; 101 patients (21%) were transfused for postoperative coagulopathy. Compared to those not transfused, patients with coagulopathy were significantly older and smaller, and they had more combined valve procedures, emergency operations, and preoperative heparin treatment as well as longer crossclamp and bypass times. Three preoperative tests showed significant differences in the coagulopathy group: activated clotting time, partial thromboplastin time, and antithrombin-III level. Four postoperative tests showed significant differences between the groups: prothrombin time, partial thromboplastin time, fibrinogen level, and fibrin split products at 10 dilutions. Patient characteristics and pre- and postoperative testing can identify patients at high risk of transfusion specifically related to coagulopathy.

Comparison of the flow capacity of free arterial grafts and saphenous vein grafts for coronary bypass surgery.

UNLABELLED There is controversy regarding the flow reserve and capacity of arterial conduits to meet the needs of the myocardium. This study compared flow in 22 free arterial bypasses to 15 saphenous vein grafts in procedures involving twenty patients. To assess the maximal flow possible, (flow capacity) graft flow was measured using a calibrated pump while perfusing blood cardioplegia through the conduit and distal anastomosis during cardiac arrest (no competitive flow). This assessment was subsequently confirmed with whole blood during myocardial contraction while on cardiopulmonary bypass. Twenty-two free arterial grafts were used; 15 right internal mammary artery grafts, 4 right gastroepiploic grafts, 3 inferior epigastric artery grafts, and 3 sequential bypasses. Free arterial conduit flow ranged from 50 to 180cc/ml, with an average flow of 102.5+/-28.5ml/min as compared to saphenous vein graft flow, 102+/-28 ml/min. No correlation of flow with the conduit size was found. Arterial graft flow demonstrated a mild correlation with the size of the native coronary artery bypassed (R=0.47, P</=0.02). CONCLUSIONS Basal flow through free arterial grafts is equivalent to saphenous vein grafts and is primarily determined by the native coronary vessels. The flow reserve for free arterial conduits is more than adequate for coronary bypass surgery.