Fontan Physiology Ventilation Strategy

Impact of Fontan Ventilation Strategy on Cardiac Output: An Invasive Physiologic Cross-over Study

This study will investigate the different tidal volume (Vt) strategies during a cardiac catheterization procedure to determine whether or not low or high Vt have an impact on cardiac output.

Research question: While maintaining the same minute ventilation/PaCO2, does higher Vt (10 cc/kg)/lower rate vs. lower Vt (6 cc/kg)/higher rate (maintaining consistent PEEP) result in improved cardiac output?

The trial will be a randomized crossover design. The study cohort will be randomized (50/50) to begin with either low Vt or high Vt ventilation. After achieving steady state, initial cardiac output measurements will be made using a measured oxygen consumption (VO2) and the Fick principle, per routine clinical protocol. Following baseline assessment of cardiac output and hemodynamics (which is standard of care for all catheterization procedures), participants will be transitioned to the alternative ventilation modality (high Vt or low Vt). After a 5-minute equilibration period, oxygen saturations and VO2 measurements will be re-acquired, to determine cardiac output and hemodynamics in this second state.

Inclusion Criteria:

• Patients of UPMC Children's Hospital of Pittsburgh that have Fontan physiology (single heart ventricle) that are presenting as outpatients to undergo a cardiac catheterization with general endotracheal anesthesia for purpose of diagnosis or interventional cath.
• Parents and/or guardians willing to provide informed consent.

Exclusion Criteria:

• Those unwilling to give consent and those patients who do not have Fontan physiology.
• Any urgent/emergent catheterization procedure will be excluded.
• Any Fontan patient having a cardiac catheterization under monitored anesthesia care (as opposed to general endotracheal anesthesia) will not be eligible.
• Inability to undergo cardiac catheterization.
• Pregnant women will be excluded.
• < 6 weeks post-op from Fontan completion surgery
• Same hospitalization as Fontan completion surgery
• Intrinsic pulmonary disease which would be anticipated to impact study protocol / findings
• Fontan completion surgery performed at age > 7 years