Graft Downsizing During Ex Vivo Lung Perfusion: Case Report and Technical Notes

Among patients with respiratory insufficiency awaiting lung transplantation, small adult patients have a lower opportunity of receiving size-matched pulmonary grafts, because of the shortage of donors, particularly those of small size. Reducing the size of an oversized graft is one of the methods to increase the donor pool; similarly, ex vivo lung perfusion is an emerging technique aimed toward the same purpose. We describe how we combined the 2 techniques (lobar transplantation plus contralateral nonanatomic graft reduction during ex vivo lung perfusion) to overcome graft shortage in a clinical case. For the 1st time, this case report demonstrates that surgical manipulation during ex vivo lung perfusion does not affect the functional improvement in a lung previously judged to be not suitable for transplantation. The 6-month follow-up results are similar to those of standard bilateral lung transplantation.     

Evidence of Air Trapping During Ex Vivo Lung Perfusion: A Swine Experimental Lung Imaging and Mechanics Study

Ex vivo lung perfusion (EVLP) allows the ventilation and perfusion of lungs to evaluate their viability for transplantation. The aim of this study is to compare the mechanical, morphologic and functional properties of lungs during EVLP with values obtained in vivo to guide a safe mechanical ventilation strategy.Lungs from 5 healthy pigs were studied in vivo and during 4 hours of EVLP. Lung compliance, airway resistance, gas exchange, and hemodynamic parameters were collected at positive end-expiratory pressure (PEEP) of 5 cm H₂O. Computed tomography was performed at PEEP 0, PEEP 5, and total lung capacity (TLC). Lung pressure-volume (PV) curves were performed from PEEP 0 to TLC.Lung compliance decreased during EVLP (53 ± 5 mL/cm H₂O vs 29 ± 7 mL/cm H₂O, P < .05), and the PV curve showed a lower inflection point. Gas content (528 ± 118 mL vs 892 ± 402 mL at PEEP 0) and airway resistance (25 ± 5 vs 44 ± 9 cmH₂O/L1s^-1, P < .05) were higher during EVLP. Alveolar dead space (5% ± 2% vs 17% ± 6%, P < .05) and intrapulmonary shunt (9% ± 2% vs 28% ± 13%, P < .05) increased ex vivo compared to in vivo, while the partial pressure of oxygen to inspired oxygen fraction ratio (PO₂/FiO₂) did not differ (468 ± 52 mm Hg vs 536 ± 14 mm Hg).In conclusion, during EVLP lungs show signs of air trapping and bronchoconstriction, resulting in low compliance and increased alveolar dead space. Intrapulmonary shunt is high despite oxygenation levels acceptable for transplantation.     

Ex Vivo Lung Perfusion Increases the Pool of Lung Grafts: Analysis of Its Potential and Real Impact on a Lung Transplant Program

Background

Among the strategies to increase the number of lung transplants, ex vivo lung perfusion (EVLP) represents a novel technique to expand the donor pool.

Methods

Data from donors referred to our center were retrospectively analyzed to identify grafts that could potentially be potentially reconditioned by EVLP and for comparison with those obtained by clinical application of EVLP program in our center.

Results

Among 75 rejected lungs, 23 organs have been identified as potentially treatable with EVLP with a hypothetic increase of lung transplant activity of 53%. After the introduction of the EVLP program in our center, lung transplantation with reconditioned grafts was performed in 7 (23%) patients with a 30% increase in transplant procedures.

Conclusion

Although less than expected, EVLP increased the number of lungs suitable for transplantation.     

Protection From the Second Warm Ischemic Injury in Kidney Transplantation Using an Ex Vivo Porcine Model and Thermally Insulating Jackets

BackgroundKidney transplantation is the optimum treatment for kidney failure in carefully selected patients. Technical surgical complications and second warm ischemic time (SWIT) increase the risk of delayed graft function (DGF) and subsequent short- and long-term graft outcomes including the need for post-transplant dialysis and graft failure. Intraoperative organ thermal regulation could reduce SWIT, minimizing surgical complications due to time pressure, and limiting graft ischemia-reperfusion injury.MethodsA novel ischemic-injury thermal protection jacket (iiPJ) was designed and fabricated in silicone composite and polyurethane (PU) elastomer prototypes. Both were compared with no thermal insulation as controls. Time to reach ischemic threshold (15°C) and thermal energy transfer were compared. A water bath model was used to examine the thermal protective properties of porcine kidneys, as a feasibility study prior to in vivo translation.ResultsIn both iterations of the iiPJ, the time taken to reach the warm ischemia threshold was 35.2 ± 1.4 minutes (silicone) and 38.4 ± 3.1 minutes (PU), compared with 17.2 ± 1.5 minutes for controls (n = 5, P < .001 for both comparisons). Thermal energy transfer was also found to be significantly less for both iiPJ variants compared with controls. There was no significant difference between the thermal performance of the 2 iiPJ variants.ConclusionProtection from SWIT by using a protective insulation jacket is feasible. With clinical translation, this novel strategy could facilitate more optimal surgical performance and reduce transplanted organ ischemia-reperfusion injury, in particular the SWIT, potentially affecting delayed graft function and long-term outcomes.     

Successful Lung Salvage by Ex Vivo Reconditioning of Neurogenic Pulmonary Edema: Case Report

Liberalization in donor selection criteria allowed centers to increase the number of lung transplants, yet less than 25 % of all donors had lungs utilized for transplantation in the United States in 2013. Less than 5% of all transplanted donors deviate 3 or more criteria from the ideal donor. Ex vivo lung perfusion (EVLP) provides the opportunity to increase the percentage of used donors by acting on modifiable selection criteria such as oxygenation, contusion and pulmonary infiltrates. We report the pre-transplant use of EVLP in the salvage of lungs from a donor that developed neurogenic pulmonary edema -PaO₂ 188 mmHg-. The recipient had a lung allocation score of 69.3. The post-operative course was excellent and was discharged home after 15 days. He is alive and doing well 780 days after transplant. In this report the pre-transplant use of EVLP led not only to transplanting lungs that otherwise would not have been used by many centers, but also to a very short and typical period of post-operative mechanical ventilation and hospital stay.     

Acute Kidney Injury After Liver Transplantation: Incidence and Mortality

Introduction

Patients undergoing orthotopic liver transplantation often present with acute kidney injury (AKI) in the postoperative period. It has been associated with a greater number of complications and high mortality rates. The goal of this study was to determine the incidence of AKI during the early posttransplant period and mortality in patients undergoing orthotopic liver transplantation in our hospital.

Patients and Methods

In this retrospective cohort study, we reviewed the medical records of all patients aged >18 years undergoing liver transplantation from April 2008 to April 2011. The exclusion criteria were a glomerular filtration rate (estimated by using the Modification of Diet in Renal Disease formula) <60 mL/min/1.73 m² or AKI at the time of transplantation. AKI was defined as an increase ≥50% from preoperative baseline serum creatinine levels during the hospitalization period.

Results

Of 113 selected patients, 78 (69%) were male. The mean age was 54.03 ± 9.38 years. The mean preoperative baseline creatinine level was 0.94 ± 0.15 mg/dL, and the estimated glomerular filtration rate was 87.09 ± 19.67 mL/min/1.73 m². The mean calculated Model for End-Stage Liver Disease score was 13. Hepatitis C serology was present in 70.8%, hepatitis B in 11.5%, hepatocellular carcinoma in 75.2%, and alcohol abuse in 31.9% of patients. The incidence of AKI was 56.6% (64 of 113 patients). The main risk factors for AKI were Model for End-Stage Liver Disease score and diuretic use at baseline. Renal replacement therapy (RRT) was performed in 19.5% (22 of 113) of patients. The hospital mortality rate in the group with AKI was 25% (16 of 64 patients) and 6.1% (3 of 49 patients) between patients without AKI (odds ratio, 5.11 [confidence interval, 1.39–18.7]; P < .01]. Among patients who underwent RRT, the in-hospital mortality rate was 54.5% (12 of 22 patients) compared with 7.7% (7 of 91 patients) from the other remaining patient cohort (odds ratio, 14.40 [confidence interval, 4.60–45.00]; P < .01).

Conclusions

There was a high incidence of AKI in patients undergoing liver transplantation and an increased risk of mortality among patients who needed RRT.