Abstract
Background: High 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 (RIP), we investigated the effects of HFNC on thoraco-abdominal synchrony.
Methods: We studied 40 adult patients requiring oxygen therapy in the intensive care unit. Low-flow oxygen (up to 8 litre min−1) was administered to the patients via face mask for 30 min followed by HFNC at a flow of 30–50 litre min−1. RIP transducer bands were circumferentially placed, one around the rib cage (RC) and one around the abdomen (AB). We measured the movement of RC, AB and used the sum signal to represent tidal volume (VT) during face-mask breathing and at 30 min after start of HFNC. We calculated two quantitative indexes; maximum compartmental amplitude/VT ratio (MCA/VT); and phase angle. We assessed arterial blood gas and vital signs at each period, and mouth status during HFNC. To clarify factors associated with improvement in thoraco-abdominal synchrony, multiple regression analysis was applied to the data.
Results: Respiratory rate statistically significantly decreased from 25 (22-28) to 21 (18-24) breath min−1 after the start of HFNC (P < 0.001). With HFNC, patients showed significant improvement in MCA/VT (P < 0.001) and phase angle (P < 0.05).
Conclusions: HFNC improved thoraco-abdominal synchrony in adult patients with mild-to-moderate respiratory failure.
- high flow oxygen therapy
- nasal cannula
- thoraco-abdominal synchrony
- respiratory inductive plethysmography
- acute respiratory failure
- critical care
Footnotes
- Corresponding Author:
Masaji Nishimura MD PhD, Department of Emergency and Critical Care Medicine, The University of Tokushima Graduate Shool, 3-18-15 Kuramoto-cho, Tokushima, Japan 770-8503, Telephone: +81 88 633 9347, Fax: +81 88 633 9339, E-mail address: nmasaji{at}tokushima-u.ac.jp
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