5. Twenty-Four Hour Ex Vivo lung Perfusion: Strategies to Stabilize Extended EVLP in a Pig Model.
Takahashi M, Cheung H, Chen M, et al, – J Heart Lung Transplant. 37, 45, April 2018, Suppl S223-4
The Toronto protocol for normothermic ex vivo lung perfusion (EVLP) has been successfully applied experimentally and clinically as a method for donor lung assessment and treatment of injured lungs. However, the current protocol is reliable only up to 12 hrs and this limits potential advances in therapeutic and reconditioning strategies. We have noted that the composition of Steen solution changes over time during extended EVLP. Loss of glucose and accumulation of electrolytes are prominent features. We thus sought to determine whether a Continuous Replacement (CR) or a modified feed (MF) strategy could be used to improve the stability of normothermic EVLP to reliably preserve lung integrity for an extended perfusion time (24 hrs).
Pig lungs were placed in the EVLP system for 24 hrs. Lungs were divided into three groups (n=4 per group): 1. Conventional Toronto EVLP (Control), 2. Continuous Replacement (CR), and 3. Modified Feed (MF). In the Control group, we added 100 mL Steen every 2 hrs (our current feeding strategy). In CR group, we continuously injected fresh Steen at 50 mL/hr. In MF group, we controlled the glucose levels (>10 mmol/l) and sodium levels (<155 mmol/l) by adding 5% glucose solution and water to Steen calculated to maintain stable perfusate glucose and sodium levels.
3 out of 4 lungs in the Control group failed to complete 24 h EVLP (Perfusion times: 18, 19, 20, 24 hrs). In the MF group, 3 out of 4 lungs were able to maintain stable glucose and electrolyte concentrations, and only 3 out of 4 lungs completed 24h EVLP (Perfusion times: 23, 24, 24, 24 hrs). Notably, all lungs in the CR group successfully completed 24 h EVLP.
We have shown that modifications of the technique of replenishment of the perfusate can significantly improve stability of the EVLP process. Further research is required to determine additional methods to extend EVLP for lung repair, reconditioning and immunomodulation.