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.

OBJECTIVE: Compare the short-term benefit of high-flow nasal cannula (HFNC) with nonrebreathing mask in terms of change in dyspnea, physiologic variables, and patient comfort in subjects after endotracheal extubation. METHODS: A randomized crossover study was conducted in a 10-bed respiratory care unit in a university hospital. Seventeen mechanically ventilated subjects were randomized after extubation to either Protocol A (applied HFNC for 30 min, followed by non-rebreathing mask for another 30 min) or Protocol B (applied non-rebreathing mask for 30 min, followed by HFNC for another 30 min). The level of dyspnea, breathing frequency, heart rate, blood pressure, oxygen saturation, and patient comfort were recorded. The results were expressed as mean ؎ SD, frequency, or percentage. Categorical variables were compared by chi-square test or Fisher exact test, and continuous variables were compared by dependent or paired t test. Statistical significance was defined as P < .05. RESULTS: Seventeen subjects were divided into 2 groups: 9 subjects in Protocol A and 8 subjects in Protocol B. The baseline characteristics and physiologic parameters before extubation were not significantly different in each protocol. At the end of study, HFNC indicated less dyspnea (P ‫؍‬ .04) and lower breathing frequency (P ‫؍‬ .009) and heart rate (P ‫؍‬ .006) compared with non-rebreathing mask. Most of the subjects (88.2%) preferred HFNC to non-rebreathing mask. CONCLUSIONS: HFNC can improve dyspnea and physiologic parameters, including breathing frequency and heart rate, in extubated subjects compared with conventional oxygen therapy. This device may have a potential role for use after endotracheal extubation.

Poor growth, Pseudomonas aeruginosa endobronchitis, pulmonary inflammation, and decline of lung function are hallmarks of cystic fibrosis (CF), yet the relationship between these features is poorly understood. Because animal models of chronic bronchopulmonary infection with P. aeruginosa used to study pulmonary inflammation in CF have also been associated with weight loss, we sought to determine whether this weight loss was due to the inflammatory process and/or to changes in lung function. P. aeruginosa-laden agarose beads were instilled into the lungs of mice. Weight loss was greatest 3 d after Pseudomonas infection. Infected mice had a rapid though transient rise in absolute neutrophil counts, mTNF-alpha, mIL-1beta, mIL-6, mip-2, and KC in bronchoalveolar lavage fluid. There was no difference in lung resistance or lung compliance measured by body plethysmography between infected and control mice. Weight loss did correlate with the concentration of proinflammatory cytokine levels 3 d after inoculation of mice with Pseudomonas, and body composition analysis revealed loss of skeletal muscle mass. These results suggest that weight loss in P. aeruginosa-infected mice was associated with the inflammatory process and not with altered pulmonary responsiveness. These findings may provide insights into the cause of cachexia and weight loss seen in patients with CF.

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.