Comparison of the effect of inhaled anaesthetic with intravenous anaesthetic on pulmonary vascular resistance measurement during cardiac catheterisation

BACKGROUND: Children with pulmonary hypertension routinely undergo pulmonary vascular resistance studies to assess the disease severity and vasodilator responsiveness. It is vital that results are accurate and reliable and are not influenced by the choice of anaesthetic agent. However, there are anecdotal data to suggest that propofol and inhalational agents have different effects on pulmonary vascular resistance. METHODS: A total of 10 children with pulmonary hypertension were selected sequentially to be included in the study. To avoid confounding because of baseline anatomic or demographic details, a crossover protocol was implemented, using propofol or isoflurane, with time for washout in between each agent and blinding of the interventionalist. RESULTS: Pulmonary and systemic vascular resistance were not significantly different when using propofol or isoflurane. However, the calculated resistance fraction - ratio of pulmonary resistance to systemic resistance - was significantly lower when using propofol than when using isoflurane. CONCLUSIONS: Although no difference in pulmonary vascular resistance was demonstrated, this pilot study suggests that the choice of anaesthetic agent may affect the calculation of relative pulmonary and systemic vascular resistance, and provides some preliminary evidence to favour propofol over isoflurane. These findings require replication in a larger study, and thus they should be considered in future calculations to make informed decisions about the management of children with pulmonary hypertension.