Page 62 - ANZCP Gazette May 2023

METHODOLOGY: Data from bypass records and patient histories; where available, were collated on a year by year basis. Demographic and bypass data were analysed for changes in patient age, size, bypass time, cross clamp time, circulatory arrest time, prime volume, length of stay and rate of reoperation.
RESULTS: There have been changes in all measured parameters over the forty years. While patients have trended to being younger and smaller, bypass and cross clamp times are variable. Circulatory arrest has disappeared altogether. Length of Stay appears to have increased. Rate of Reoperation has fallen for Tetralogy of Fallot.
CONCLUSION: Over 40 years the outlook for patients has improved. Changes in parameters measured, apart from the patient demographics, are due to a number of factors. The important changes are the elimination of circulatory arrest, minimisation of use of donor blood, and the reduction in reintervention. Have the outcomes improved as indicated by these basic parameters, or has improvement been achieved by advances in monitoring and use of database information.
PAEDIATRIC ECMO: ALTERNATIVE ANTICOAGULATION STRATEGIES FOR ECMO PURPOSE
Stephen Horton
Royal Childrens Hospital, VIC
PURPOSE: Extracorporeal membrane oxygenation (ECMO) circuits have undergone numerous modifications pertinent to their clinical environment and tasks over time, however identical anticoagulation strategies have remained. Unfractionated heparin (UFH) is the default anticoagulant for ECMO, detected in 1916 and made available as a purified substance for human application in the 1930s, UFH is one of the oldest drugs still in use. To reduce the morbidity associated with circuit clotting & subsequent patient coagulopathy we have been routinely using nitric oxide (NO) which can be safely delivered through the sweep gas to the oxygenator of an ECMO circuit in conjunction with prostacyclin. By preventing platelet adhesion to artificial surfaces, mitigating the systemic inflammatory response and protection against ischaemia-reperfusion injury it may improve oxygen delivery to hypoxic tissue. Bivalirudin, a direct thrombin inhibitor has also been used to remove or significantly reduce the use of UFH.
METHODS: The clinical outcomes of those who received NO & prostacyclin through the oxygenator were compared with those who did not. Inverse probability of treatment weights constructed from propensity scores were used to balance study covariates between the study groups (Treatment vs. Control). The final study estimates were additionally adjusted for the duration of
59 MAY 2023 | www.anzcp.org
ECMO. The main clinical outcomes studied were the need for circuit change, risk of brain injury and survival to hospital discharge.
RESULTS: Among 393 ECMO runs, 192/393 (49%) received NO and 201/393 (51%) did not. NO use was associated with a 37% reduction in the need for circuit change (adjusted risk ratio [aRR] 0.63, 95% confidence interval [CI] 0.42 – 0.93). The aRR (95% CI) for risk of neurological injury for those who received NO compared to those who did not was 0.72 (95% CI, 0.47 – 1.11). We observed evidence of potential heterogeneity of treatment effect for the risk of neurological injury in children who had cardiac surgery (versus those who did not): the risk of neurological injury was substantially lower in those who had cardiac surgery (aRR 0.50, 95% confidence interval [CI] 0.26 – 0.96). There was no difference in survival between the study groups.
CONCLUSIONS: NO and prostacyclin delivered through the oxygenator of ECMO circuit was associated with a reduction in the need for circuit change. This therapy was associated with reduced risk of neurological injury in children who underwent cardiac surgery. NO, Prostacyclin and Bivalirudin may be able to provide a more stable anticoagulation platform for ECMO or at the least significantly reduce our requirement for heparin.

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