194 S . Pervaiz Butt et al .: J Extra Corpor Technol 2024 , 56 , 191 – 202
Another approach to improving lung preservation involves adding nutrients and cytoprotective agents to preservation solutions . Studies using a cell culture model showed that maintaining physiological pH levels and utilizing phosphate-buffered media with colloid dextran 40 improved cell survival . Additionally , incorporating cytoprotective agents further enhanced the preservation process , offering the potential for designing more effective organ preservation solutions [ 12 ].
Overall , the advancements in lung preservation techniques have significantly improved the success and viability of LTx . The ongoing research and innovations in this field offer great promise for further optimizing lung preservation methods , leading to better outcomes for patients in need of life-saving lung transplants .
Preoperative support
Bridge to LTx using ECMO is a critical strategy for patients with end-stage lung disease who require temporary respiratory support while awaiting a suitable donor organ . Several studies on outcomes and challenges associated with ECMO as a bridge therapy for LTx , provide valuable insights as well as comparable results .
Hunt et al . explored the outcomes of COVID-19 patients bridged with ECMO before LTx . Despite higher rates of post-operative complications , ECMO patients did not show significant differences in survival rates at 1 and 6 months posttransplant compared to non-ECMO patients . These findings suggest that ECMO can be safely used as a bridge to LTx in carefully selected COVID-19 patients with respiratory failure , even with prolonged support [ 13 ].
Sainathan et al . found in paediatric patients aged 12 – 18 years that the patients bridged to LTx with ECMO had comparable one-year and three-year survival rates to nonbridged patients , despite higher acuity , indicating that ECMO offers acceptable operative mortality and long-term survival rates in this age group [ 14 ].
Ko et al . conducted a multicentre prospective observational study , again finding comparable outcomes in patients bridged with ECMO to LTx compared to the control group , with no significant differences in post-transplant complications and hospital mortality [ 15 ].
Fischer et al . investigated the utilization of the pumpless interventional lung assist device called NovaLung as a bridge to LTx for patients with severe ventilation-refractory hypercapnia . The findings of the study revealed the remarkable effectiveness of NovaLung in enhancing oxygenation and acid-base balance , resulting in successful bridging and an impressive 80 % one-year survival rate after transplantation [ 16 ].
Oh et al ., however , evaluated the impact of ECMO as a bridge to LTx ( BTT ) on post-transplant outcomes . Although the bridge-ECMO group showed comparable 1-year and 5-year post-transplant survival rates to the non-BTT group , long-term ECMO bridging ( 14 days ) was identified as an independent risk factor for 1-year post-transplant mortality demonstrating potential risks [ 17 ]. In addition Atchade et al . highlighted the impact of ECMO as a bridge to LTx on bronchial anastomotic dehiscence ( BAD ) occurrence . ECMO support was identified as an independent risk factor for BAD , emphasizing the need for close monitoring and vigilance in high-risk recipients during the early post-operative period [ 18 ].
A retrospective study done by Rando et al . using the United Network for Organ Sharing ( UNOS ) database , looked at 40,866 patients over the age of 19 years , of whom 1387 ( 3.4 %) were on ECMO and 39,479 ( 96.6 %) had no ECMO . Average age and initial Lung Allocation Score increased significantly during the study period in both cohorts but occurred slower in the ECMO population . The hazard of death was significantly lower in years 2015 – 2019 for both the ECMO and non-ECMO cohorts with an adjusted hazards ratio ( aHR ) of 0.59 , 95 % confidence interval ( CI ) 0.37 – 0.96 and aHR of 0.74 , 95 % CI 0.70 – 0.79 , when compared to the early years 2000 – 2004 . The study highlighted that post-transplantation survival was higher for patients bridged to transplantation with ECMO , and demonstrates ongoing improvement despite cannulation of progressively older and sicker patients [ 19 ].
The development of risk assessment tools such as the STABLE score by Habertheuer et al . may contribute to some improved outcomes . The score provides a valuable risk assessment tool for predicting in-hospital mortality in patients requiring ECMO as a bridge to LTx . This score can aid clinicians in stratifying risk and making informed decisions to potentially improve post-transplant outcomes [ 20 ].
In another study on the use of ECLS as a bridge to LTx in a larger cohort of patients , out of 1111 lung transplants performed over a 10-year period , 71 adults received ECLS as a bridging therapy . The majority of patients survived LTx , with an overall survival rate of 89 % demonstrating its use . However , the study highlighted an important distinction between patients bridged to first lung transplant and those bridged to re-transplantation . Patients bridged to re-transplantation had significantly shorter survival compared to those bridged to first lung transplant . This suggests that caution should be exercised when considering ECLS as a bridge to re-transplantation although this is not as common on the whole [ 21 ].
Collectively , these studies demonstrate the significance of ECMO as a bridge to LTx , offering option to patients with severe respiratory failure . ECMO provides temporary respiratory support , stabilizing patients ’ conditions and preserving vital organ function while awaiting a donor organ . Careful patient selection and close monitoring of potential complications are essential to ensure successful bridging and optimal post-transplant outcomes . In patients with chronic respiratory failure , ECMO as a bridge helps to stabilize the potential recipient in multiple ways as discussed . In patients with prolonged acute respiratory failure secondary to primary pneumonia , long ECMO runs have provided important insights for lung recovery in acute illness .
Patients with advanced age , those with organ failures other than lung , severe deconditioning secondary to malnutrition , and neuromyopathy are likely to have poor outcomes and should not be routinely considered for ECMO as a bridge to LTx . As the understanding of ECMO ’ s role in LTx continues to evolve , these barriers would reduce and more critically ill patients could be considered for ECMO as a bridge to LTx in coming years .