• Pornpan Rattanajiajaroen and Napplika Kongpolprom.
• Division of Pulmonary and Critical Care Medicine, Department of Medicine, Faculty of Medicine, Chulalongkorn University, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, Thailand. p.rattanajiajaroen@gmail.com.
• Crit Care. 2021 Oct 19; 25 (1): 365.

BackgroundTiming 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.ObjectivesTo 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).MethodsWe conducted a randomized controlled crossover study in post-extubation patients. The patients extubated within 48 h were randomly assigned to two groups, namely, HFNO and LFNO. The eligible patients in each group received either HFNO with fraction of inspired oxygen (FiO2) 0.35, flow 50 L per minute (LPM), and temperature 34 °C or LFNO 5 LPM for 5 min. The coordination between swallowing and respiration was observed during continuous infusion of 10-ml water one minute three times. Respiratory phases and swallowing were monitored using electrocardiogram (EKG)-derived respiratory signals and submental electromyography (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 a 5-min washout period, the patients were switched to the other type of oxygen therapy using the same procedure. The Wilcoxon Signed-Rank Test was used for statistical analysis.ResultsA total of 22 patients with a mean age of 56 years were enrolled in the study. The major indication for invasive mechanical ventilation was pneumonia with a median duration of endotracheal intubation of 2.5 days. The median total swallowing numbers (three minutes) were 18.5 times in the HFNO period and 21 times in the LFNO period (p = NS). 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 the 2 groups.ConclusionsCompared with LFNO, HFNO significantly increased the E-swallow and decreased the I-swallow in post-extubation patients. The findings indicated that HFNO might reduce a risk of aspiration during the post-extubation period. Clinical trial No.: Thai clinical trial TCTR20200206004 Registered February 4, 2020. URL: http://www.clinicaltrials.in.th/index.php?tp=regtrials&menu=trialsearch&smenu=fulltext&task=search&task2=view1&id=5740 .© 2021. The Author(s).

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