Non-invasive assessment of intrapulmonary shunt and ventilation to perfusion ratio in children with hepatopulmonary syndrome before and after liver transplantation.

Abstract Objectives To use the oxyhaemoglobin dissociation curve (ODC) to non-invasively measure the ventilation perfusion ratio (VA/Q) and right-to-left intrapulmonary vascular shunt before and after liver transplantation (LT) in children with hepatopulmonary syndrome (HPS). To investigate whether the right-to-left shunt derived by ODC correlated with the shunt derived by technetium-99 labelled macroaggregated albumin lung perfusion scan (MAA). Methods A retrospective cohort study at King's College Hospital NHS Foundation Trust, London, UK was performed between 1998 and 2016. The VA/Q and right-to-left shunt were non-invasively measured pre and post LT. The pre-LT right-to-left intrapulmonary shunt was also measured by MAA. The non-invasively derived pre-LT shunt was correlated with the shunt derived by MAA. Results Fifteen children with HPS were studied with a median (IQR) age at LT of 8.8 (6.6–12.9) years. The median (IQR) pre-LT VA/Q [0.49 (0.42–0.65)] was lower compared to the post-LT VA/Q [0.61 (IQR 0.54–0.72), p = 0.012]. The median (IQR) pre-LT shunt was 19 (3–24) % which decreased to zero in all but one children post-LT, (p = 0.001). The MAA-derived shunt was significantly positively correlated with the ODC-derived shunt (r = 0.783, p = 0.001). The mean (SD) difference between shunt derived by ODC and shunt derived by MAA was 0.5 (7.2) %. Conclusions Ventilation/perfusion impairment reverses but not completely resolves after liver transplantation in children with hepatopulmonary syndrome. The non-invasive method for estimating intrapulmonary shunting could be used as an alternative to the macroaggregated albumin scan in this population.