Temporal effects of caffeine on intrapulmonary shunt in preterm ventilated infants

We hypothesized that caffeine would be associated with a transient reduction in the right-to-left shunt and V_A/Q. We aimed to explore the temporal effects of caffeine on right-to-left shunt, ventilation perfusion ratio (V_A/Q) and shift of the oxyhaemoglobin dissociation curve (ODC) in premature ventilated infants.

Retrospective cohort study at a tertiary neonatal unit of infants born at less than 31 weeks of gestation that were mechanically ventilated on day three of life. The non-invasive method of the ODC was used to determine the right-to-left shunt, V_A/Q and shift before and at 1, 4 and 20 h after a maintenance dose of caffeine citrate.

A total of 21 infants were included with a median (range) gestational age of 27 (23.7-30.7) weeks. The median shunt percentage was significantly reduced, compared to baseline at 1 h (8 (range: 7-9) % vs. 4 (range: 0-6) %, p=0.042) and 4 h post caffeine administration (8 (range: 7-9) % vs. 0 (range: 0-3) %, p=0.042), but the V_A/Q and the right shift of the ODC did not differ significantly between these time points. At 20 h, there were no significant differences between these indices compared to baseline values.

Caffeine led to a transient decrease in intrapulmonary shunt from one to 4 h after administration and this may be due to its diuretic action.