High-flow nasal cannula: Impact on oxygenation and ventilation in an acute lung injury model

Introduction High‐flow nasal cannula therapy (HFNC) has been shown to be more effective than continuous positive airway pressure (CPAP) in reducing intubations and ventilator days. HFNC likely provides mechanisms to support respiratory efficiency beyond application of distending pressure. We reason that HFNC washout of nasopharyngeal dead space impacts CO2 removal along with oxygenation. The aim of this study was to demonstrate the flow dependence of CO2 reduction and improved oxygenation during HFNC and the dependence on leak around the nasal prongs. Materials and Methods Neonatal piglets (n = 13; 2–6 kg) were injured with IV oleic acid and supported with HFNC at 2 through 8 L/min. High and low leak around the nasal prongs was accomplished by using single and double prong cannulae, respectively. Measurement of hemodynamic, respiratory and blood gas parameters were made at each setting following 10 min for physiologic equilibration. Tracheal pressures were recorded by transmural catheters. Results With HFNC, CO2 trended downward in a flow‐dependent manner independent of leak. Oxygenation and tracheal pressures increased in a flow‐dependent manner with the greatest effect during double prong. At 8 L/min, tracheal pressures did not exceed 6 ± 1 cmH2O. Conclusions HFNC improves gas exchange in a flow‐dependent manner; double prong had greater impact on O2; single prong had greater impact on CO2 elimination. Pediatr Pulmonol. 2011; 46:67–74. © 2010 Wiley‐Liss, Inc.