Cardiac output during flow-titrated high-flow nasal cannula support in a neonatal porcine model

Background: Neonates are more susceptible to acute respiratory failure than older children. It is unknown to what extent high-flow nasal cannula (HFNC) alters intrathoracic pressure (ITP), potentially decreasing cardiac output (CO) due to cardiopulmonary interactions. This study evaluated the impact of flow titration on tracheal pressure (a surrogate for ITP) and CO via HFNC in an established porcine model of neonatal respiratory failure. Unlike prior research, this study examines both ITP and CO demonstrating that although the ITP increased with higher HFNC flows, CO did not decrease. Methods: Twenty-three neonatal Landrace-Yorkshire pigs (2–4 kg) were anesthetized, and monitoring lines were placed. Baseline vital signs, CO, mean intratracheal pressure (Ptr), and PaO ₂ were measured. CO was assessed via computerized COstatus cardiac system. Lung injury was induced using oleic acid (0.08 mL/kg), resulting in ≤50% reduction in preinjury PaO ₂ on 1 L/min oxygen. After injury, in random order, pigs received HFNC flows of 1, 2, and 3 L/kg/min at 100% FiO ₂ for 30 min each. Measurements were repeated, and data were analyzed via mixed-effects repeated measures ANOVA. Results: After OA injury, PaO ₂ significantly decreased (414 to 125 mmHg; p < 0.001). Mean Ptr and PaO ₂ increased significantly (p < .001) with increasing HFNC flow rates. CO showed no significant changes; thus, no correlation between CO with Ptr and/or HFNC flow levels was demonstrated. Conclusions: In neonatal respiratory distress, higher HFNC flows improved oxygenation without negatively impacting CO in this neonatal porcine lung injury model, despite increasing intra-thoracic pressure (1–3 L/min/kg).