BACKGROUND: Acute dyspnea and hypoxemia are 2 of the most common problems in the emergency room. Oxygen therapy is an essential supportive treatment to correct these issues. In this study, we investigated the physiologic effects of high-flow nasal oxygen cannula (HFNC) compared with conventional oxygen therapy (COT) in subjects with acute dyspnea and hypoxemia in the emergency room. METHODS: A prospective randomized comparative study was conducted in the emergency department of a university hospital. Forty subjects were randomized to receive HFNC or COT for 1 h. The primary outcome was level of dyspnea, and secondary outcomes included change in breathing frequency, subject comfort, adverse events, and rate of hospitalization. RESULTS: Common causes of acute dyspnea and hypoxemia were congestive heart failure, asthma exacerbation, COPD exacerbation, and pneumonia. HFNC significantly improved dyspnea (2.0 ؎ 1.8 vs 3.8 ؎ 2.3, P ‫؍‬ .01) and subject comfort (1.6 ؎ 1.7 vs 3.7 ؎ 2.4, P ‫؍‬ .01) compared with COT. No statistically significant difference in breathing frequency was found between the 2 groups at the end of the study. HFNC was well tolerated, and no serious adverse events were found. The rate of hospitalization in the HFNC group was lower than in the COT group, but there was no statistically significant difference (50% vs 65%, P ‫؍‬ .34). CONCLUSIONS: HFNC improved dyspnea and comfort in subjects presenting with acute dyspnea and hypoxemia in the emergency department. HFNC may benefit patients requiring oxygen therapy in the emergency room.

In patients with cardiogenic pulmonary edema in the ED, high-flow nasal cannula therapy may decrease the severity of dyspnea during the first hour of treatment.

BackgroundNon-invasive ventilation (NIV) is preferred as the initial ventilatory support to treat acute hypercapnic respiratory failure in patients with chronic obstructive pulmonary disease (COPD). High-flow nasal cannula (HFNC) may be an alternative method; however, the effects of HFNC in hypercapnic COPD are not well known. This preliminary study aimed at assessing the physiologic effects of HFNC at different flow rates in hypercapnic COPD and to compare it with NIV.MethodsA prospective physiologic study enrolled 12 hypercapnic COPD patients who had initially required NIV, and were ventilated with HFNC at flow rates increasing from 10 to 50 L/min for 15 min in each step. The primary outcome was the effort to breathe estimated by a simplified esophageal pressure–time product (sPTPes). The other studied variables were respiratory rate, oxygen saturation (SpO2), and transcutaneous CO2 pressure (PtcCO2).ResultsBefore NIV initiation, the median [interquartile range] pH was 7.36 [7.28–7.37] with a PaCO2 of 51 [42–60] mmHg. sPTPes per minute was significantly lower with HFNC at 30 L/min than 10 and 20 L/min (p < 0.001), and did not significantly differ with NIV (median inspiratory/expiratory positive airway pressure of 11 [10–12] and [5–5] cmH2O, respectively). At 50 L/min, sPTPes per minute increased compared to 30 L/min half of the patients. Respiratory rate was lower (p = 0.003) and SpO2 was higher (p = 0.028) with higher flows (30–50 L/min) compared to flow rate of 10 L/min and not different than with NIV. No significant differences in PtcCO2 between NIV and HFNC at different flow rates were observed (p = 0.335).ConclusionsApplying HFNC at 30 L/min for a short duration reduces inspiratory effort in comparison to 10 and 20 L/min, and resulted in similar effect than NIV delivered at modest levels of pressure support in hypercapnic COPD with mild to moderate exacerbation. Higher flow rates reduce respiratory rate but sometimes increase the effort to breathe. Using HFNC at 30 L/min in hypercapnic COPD patients should be further evaluated. Trial registration Thai Clinical Trials Registry, TCTR20160902001. Registered 31 August 2016, http://www.clinicaltrials.in.th/index.php?tp=regtrials&menu=trialsearch&smenu=fulltext&task=search&task2=view1&id=2008.