S Gregory Marshall1, Nicholas R Henry2, Christopher J Russian2. 1. Department of Respiratory Care, Texas State University, San Marcos, Texas. SM10@txstate.edu. 2. Department of Respiratory Care, Texas State University, San Marcos, Texas.
Abstract
BACKGROUND: Nasal cycling may present negative consequences for oxygen-dependent patients using a nasal cannula. This study investigates the effects of nasal cycling on the delivered F(IO2) via nasal cannula in an anatomic model following a baseline study comparing right and left prong nasal cannula oxygen flow delivery. METHODS: Flow from right and left nasal cannula prongs were measured simultaneously using thermal mass flow meters while delivering 0.5-6-L/min oxygen for 5 nasal cannulas from different manufacturers. An adult mannikin head with an anatomically correct upper airway was connected to a QuickLung Breather test lung. Nasal cannula-delivered F(IO2) was recorded using a polarographic oxygen analyzer with naris occlusion simulated by inserting a 5.0 endotracheal tube into the naris and inflating the endotracheal tube cuff. Data were recorded with both nares open, for right naris occluded and left naris patent, and for left naris occluded and right naris patent at 0.5-6 L/min. RESULTS: A paired t test demonstrated statistical differences between right and left nasal cannula prong oxygen flows (P < .01). Multivariate analysis of variance demonstrated no significant differences in nasal cannula prong flow between nasal cannula manufacturers. Repeated measures analysis of variance demonstrated significant differences for measured inspired F(IO2) (P < .01) when alternating nares were occluded and patent. The Bonferroni post hoc test showed significant differences for measured F(IO2) between patent nares and right naris patent-left naris occluded (P < .01) and between patent nares and left naris patent-right naris occluded (P < .01). Measured F(IO2) decreased by as much as 0.1 when one naris was occluded. CONCLUSIONS: Oxygen delivery by nasal cannula may be inefficient in the presence of the nasal cycle. Delivered nasal cannula oxygen concentrations decreased when bilateral nasal patency changed to unilateral nasal patency. Although statistically different, nasal cannula prong oxygen flow may not be clinically important across the full range of flows.
BACKGROUND: Nasal cycling may present negative consequences for oxygen-dependent patients using a nasal cannula. This study investigates the effects of nasal cycling on the delivered F(IO2) via nasal cannula in an anatomic model following a baseline study comparing right and left prong nasal cannula oxygen flow delivery. METHODS: Flow from right and left nasal cannula prongs were measured simultaneously using thermal mass flow meters while delivering 0.5-6-L/min oxygen for 5 nasal cannulas from different manufacturers. An adult mannikin head with an anatomically correct upper airway was connected to a QuickLung Breather test lung. Nasal cannula-delivered F(IO2) was recorded using a polarographic oxygen analyzer with naris occlusion simulated by inserting a 5.0 endotracheal tube into the naris and inflating the endotracheal tube cuff. Data were recorded with both nares open, for right naris occluded and left naris patent, and for left naris occluded and right naris patent at 0.5-6 L/min. RESULTS: A paired t test demonstrated statistical differences between right and left nasal cannula prong oxygen flows (P < .01). Multivariate analysis of variance demonstrated no significant differences in nasal cannula prong flow between nasal cannula manufacturers. Repeated measures analysis of variance demonstrated significant differences for measured inspired F(IO2) (P < .01) when alternating nares were occluded and patent. The Bonferroni post hoc test showed significant differences for measured F(IO2) between patent nares and right naris patent-left naris occluded (P < .01) and between patent nares and left naris patent-right naris occluded (P < .01). Measured F(IO2) decreased by as much as 0.1 when one naris was occluded. CONCLUSIONS:Oxygen delivery by nasal cannula may be inefficient in the presence of the nasal cycle. Delivered nasal cannula oxygen concentrations decreased when bilateral nasal patency changed to unilateral nasal patency. Although statistically different, nasal cannula prong oxygen flow may not be clinically important across the full range of flows.