Ventilation-to-perfusion relationships and right-to-left shunt during neonatal intensive care in infants with congenital diaphragmatic hernia

Background We aimed to explore the postnatal evolution of ventilation/perfusion ratio (V-A/Q) and right-to-left shunt in infants with congenital diaphragmatic hernia (CDH) and whether these indices predicted survival to discharge. Methods Retrospective cohort study at King's College Hospital, London, UK of infants admitted with CDH in 10 years (2011-2021). The non-invasive method of the oxyhaemoglobin dissociation curve was used to determine the V-A/Q and shunt in the first 24 h of life, pre-operation, pre-extubation and in the deceased infants, before death. Results Eighty-two infants with CDH (71 left-sided) were included with a median (IQR) gestation of 38.1(34.8-39.0) weeks. Fifty-three (65%) survived to discharge from neonatal care. The median (IQR) V-A/Q in the first 24 h was lower in the deceased infants [0.09(0.07-0.12)] compared to the ones who survived [0.28(0.19-0.38), p < 0.001]. In the infants who survived, the V-A/Q was lower in the first 24 h [0.28 (0.19-0.38)] compared to pre-operation [0.41 (0.3-0.49), p < 0.001] and lower pre-operation compared to pre-extubation [0.48 (0.39-0.55), p = 0.027]. The shunt was not different in infants who survived compared to the infants who did not. Conclusions Ventilation-to-perfusion ratio was lower in infants who died in the neonatal period compared to the ones that survived and improved in surviving infants over the immediate postnatal period. Impact The non-invasive method of the oxyhaemoglobin dissociation curve was used to determine the ventilation/perfusion ratio A/ in infants with congenital diaphragmatic hernia (CDH) in the first 24 h of life, pre-operation, pre-extubation and in the deceased infants, before death. The A/ in the first 24 h of life was lower in the infants who did not survive to discharge from neonatal care compared to the ones who survived. In the infants who survived, the A/ improved over the immediate postnatal period. The non-invasive calculation of A/ can provide valuable information relating to survival to discharge.

Automated summary

This study aimed to explore the postnatal evolution of ventilation/perfusion ratio (V-A/Q) in infants with congenital diaphragmatic hernia (CDH) and its predictive value for survival. The results showed that the V-A/Q improved in surviving infants over the postnatal period, while it was lower in infants who did not survive.