• Hisakazu Kohata, Nao Okuda, Emiko Nakataki, Taiga Itagaki, and Yumiko Tsunano.
• Department of Emergency and Critical Care Medicine, University of Tokushima Graduate School.
• Respir Care. 2014 Jan 1;59(1):70-4.

BackgroundHigh-flow nasal cannula (HFNC) creates positive oropharyngeal airway pressure and improves oxygenation. It remains unclear, however, whether HFNC improves thoraco-abdominal synchrony in patients with mild to moderate respiratory failure. Using respiratory inductive plethysmography, we investigated the effects of HFNC on thoraco-abdominal synchrony.MethodsWe studied 40 adult subjects requiring oxygen therapy in the ICU. Low-flow oxygen (up to 8 L/min) was administered via oronasal mask for 30 min, followed by HFNC at 30-50 L/min. Respiratory inductive plethysmography transducer bands were circumferentially placed: one around the rib cage, and one around the abdomen. We measured the movement of the rib-cage and abdomen, and used the sum signal to represent tidal volume (V(T)) during mask breathing, and at 30 min during HFNC. We calculated the ratio of maximum compartmental amplitude (MCA) to V(T), and the phase angle. We assessed arterial blood gas and vital signs at each period, and mouth status during HFNC. We used multiple regression analysis to identify factors associated with improvement in thoraco-abdominal synchrony.ResultsDuring HFNC, breathing frequency significantly decreased from 25 breaths/min (IQR 22-27 breaths/min) to 21 breaths/min (IQR 18-24 breaths/min) (P < .001), and MCA/VT (P < .001) and phase angle (P = .047) significantly improved.ConclusionsHFNC improved thoraco-abdominal synchrony in adult subjects with mild to moderate respiratory failure.

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