Effects of High Flow Nasal Cannula on the Coordination between Swallowing and Breathing in Postextubation Patients, a Randomized Crossover Study

Abstract

Background: Timing of swallows in relation to respiratory phases is associated with aspiration events. Oxygen therapy possibly affects the timing of swallows, which may alter airway protective mechanisms.Objectives: To compare the coordination between swallowing and respiration during water infusion in post-extubation patients using high flow nasal oxygen(HFNO) with the coordination in those using low flow nasal oxygen(LFNO).Methods: We conducted a randomized controlled crossover study in post-extubation patients. The patients extubated within 48 hours were randomly assigned into two groups, namely HFNO and LFNO. The eligible patients in each group received either HFNO with FiO2 35%, flow 50 LPM and temperature 34˚ C or LFNO 5 LPM for 5 minutes. The coordination between swallowing and respiration was observed during continuous infusion of 10 ml of water in one minute for three times. Respiratory phases and swallowing were monitored using ECG-derived respiratory signals and submental EMG, respectively. The swallowing frequency and timing of swallows in relation to respiratory phases were recorded. The coordination between swallowing and respiration was classified into 4 patterns, namely I ,E ,I-E and E-I swallows. (I; inspiration and E; expiration) Subsequently, after the 5 minute washout period, the patients were switched to receive the other type of oxygen therapy with the same procedure. Wilcoxon Signed Ranks Test was used for statistical analysis.Results: A total of 22 patients with the mean age of 55.8 years were enrolled into the study. The major indication for invasive mechanical ventilation was pneumonia with the median duration of endotracheal intubation of 2.5 days. The median of total swallowing numbers (three minutes) were 18.5 in the HFNO period and 21 in the LFNO period (p = 0.158). The most common swallowing pattern was E swallow. The patients using HFNO had higher numbers of E-swallow pattern (74.3% in HFNO vs 67.6% in LFNO; p = 0.048) and lower numbers of I-swallow pattern (14.3% in HFNO vs 23.1% in LFNO; p = 0.044). The numbers of other swallowing patterns were not different between 2 groups.Conclusions: Compared with LFNO, HFNO significantly increased the E-swallow and decreased the I- swallow in post-extubation patients. The findings indicated that HFNO might reduce the risk of aspiration during the post-extubation period.