Heated and humidified high-flow oxygen therapy reduces discomfort during hypoxemic respiratory failure.
ABSTRACT Non-intubated critically ill patients are often treated by high-flow oxygen for acute respiratory failure. There is no current recommendation for humidification of oxygen devices.
We conducted a prospective randomized trial with a final crossover period to compare nasal airway caliber and respiratory comfort in patients with acute hypoxemic respiratory failure receiving either standard oxygen therapy with no humidification or heated and humidified high-flow oxygen therapy (HHFO(2)) in a medical ICU. Nasal airway caliber was measured using acoustic rhinometry at baseline, after 4 and 24 hours (H4 and H24), and 4 hours after crossover (H28). Dryness of the nose, mouth, and throat was auto-evaluated and assessed blindly by an otorhinolaryngologist. After the crossover, the subjects were asked which system they preferred.
Thirty subjects completed the protocol and were analyzed. Baseline median oxygen flow was 9 and 12 L/min in the standard and HHFO(2) groups, respectively (P = .21). Acoustic rhinometry measurements showed no difference between the 2 systems. The dryness score was significantly lower in the HHFO(2) group at H4 (2 vs 6, P = .007) and H24 (0 vs 8, P = .004). During the crossover period, dryness increased promptly after switching to standard oxygen and decreased after switching to HHFO(2) (P = .008). Sixteen subjects (53%) preferred HHFO(2) (P = .01), especially those who required the highest flow of oxygen at admission (P = .05).
Upper airway caliber was not significantly modified by HHFO(2), compared to standard oxygen therapy, but HHFO(2) significantly reduced discomfort in critically ill patients with respiratory failure. The system is usually preferred over standard oxygen therapy.
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ABSTRACT: /st>Respiratory complications after cardiac surgery increase morbidity, mortality, and length of stay. Studies suggest that routine delivery of positive airway pressure after extubation may be beneficial. We sought to determine whether the routine administration of nasal high-flow oxygen therapy (NHF) improves pulmonary function after cardiac surgery. /st>A pragmatic randomized controlled trial; participants received either NHF (45 litre min(-1)) or usual care from extubation to Day 2 after surgery. The primary outcome was number of patients with / ratio ≥445 on Day 3 after surgery. The secondary outcomes included atelectasis score on chest X-ray; spirometry; intensive care and hospital length of stay; mortality on Day 28; oxygenation indices; escalation of respiratory support; and patient comfort. /st>We randomized 340 patients over 14 months. The number of patients with a / ratio of ≥445 on Day 3 was 78 (46.4%) in the NHF group vs 72 (42.4%) standard care [odds ratio (OR) 1.18, 95% confidence interval (CI) 0.77-1.81, P=0.45]. was reduced at both 4 h post-extubation and at 9 a.m. on Day 1 in the NHF group (5.3 vs 5.4 kPa, P=0.03 and 5.1 vs 5.3 kPa, P=0.03, respectively). Escalation in respiratory support at any time in the study occurred in 47 patients (27.8%) allocated to NHF compared with 77 (45%) standard care (OR 0.47, 95% CI 0.29-0.7, P=0.001). /st>Routine use of NHF did not increase / ratio on Day 3 but did reduce the requirement for escalation of respiratory support.Trial RegistrationAustralia New Zealand Clinical Trials Registry www.anzctr.org.au (ACTRN12610000973011).BJA British Journal of Anaesthesia 08/2013; · 4.24 Impact Factor
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ABSTRACT: Currently conventional oxygen therapy is the first choice symptomatic treatment in the management of acute respiratory failure (ARF). However, conventional oxygen therapy has important limitations which have lead to the development of heated and humidified high-flow nasal oxygen therapy (HFNO). HFNO is an innovative technique that can deliver, through special nasal cannulae, up to 100% of the inspired fraction (FiO2) with heated and humidified oxygen at a maximum flow of 70L/min. The characteristics of this technique (overcoming the patient's spontaneous inspiratory flow, heated humidification,) and its physiological effects (no dilution of FiO2, positive end-expiratory pressure, pharyngeal dead-space washout, decrease in airway resistance), allow efficient optimization of oxygenation with better tolerance for patients. Current data, mainly observational, show that HFNO could be used particularly for the management of hypoxemic ARF, notably in the more severe forms. Indications for using HFNO, alone or in association with noninvasive ventilation, are potentially very broad and may involve different types of ARF (post-operative, post-extubation, palliative care) and even the practice of invasive technical procedures (bronchial fibroscopy). However, though current studies are very encouraging and promise a clinical benefit on patient outcomes, randomized trials are still needed to demonstrate that HFNO avoids the need for endotracheal intubation in the management of ARF.Revue des Maladies Respiratoires 10/2013; 30(8):627-43. · 0.50 Impact Factor
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ABSTRACT: Objective: Nasal high flow (NHF) has been shown to increase expiratory pressure and reduce respiratory rate but the mechanisms involved remain unclear. Methods: Ten healthy participants [age 22±2) years; body mass index (BMI) 24±2 kg/m(2)], were recruited for determining ventilatory responses to NHF of air at 37°C and fully saturated with water. We conducted a randomized, controlled, cross-over study consisting of four separate ~60-minute visits, each one week apart, to determine the effect of NHF on ventilation during wakefulness (NHF at 0, 15, 30, 45 L/min) and sleep (NHF at 0, 15 and 30 L/min). In addition, a nasal cavity model was used to compare pressure/air-flow relationships of NHF and continuous positive airway pressure (CPAP) throughout simulated breathing. Results: During wakefulness, NHF led to an increase in tidal volume from 0.7±0.1 L to 0.8±0.2, 1.0±0.2, and 1.3±0.2 L and a reduction in respiratory rate (f(R)) from 16±2 to 13±3, 10±3, and 8±3 breaths/min (baseline to 15, 30, 45 L/min NHF, respectively, P < 0.01). In contrast, during sleep NHF led to a ~20% fall in minute ventilation due to a decrease in tidal volume and no change in f(R). In the nasal cavity model, NHF increased expiratory but decreased inspiratory resistance depending on both the cannula size and the expiratory flow rate. Conclusions: The mechanisms of action for NHF differ from those of CPAP and are sleep/wake-state dependent. NHF may be utilized to increase tidal breathing during wakefulness and to relieve respiratory loads during sleep.Journal of Applied Physiology 02/2013; · 3.48 Impact Factor