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Three Part Question

In [adult patients with acute respiratory failure] does [oxygen therapy via high flow nasal cannulae] result in [improved oxygenation and or / symptoms].

Clinical Scenario

A 62 year old man is brought in to hospital with a 48 hour history of breathlessness, a productive cough and fever. He is tachypnoeic and hypoxaemic with SpO2 on air of 89%. His oxygen saturations correct to 98% with high flow oxygen via a facemask. However, he is confused and uncomfortable and repeatedly removes the facemask resulting in recurrent desaturations. You wonder whether there is an effective alternative to face mask oxygen that he is more likely to tolerate.

Search Strategy

Medline 1950 to 5/11/12
(high [All Fields] AND flow [All Fields] AND (\"nose\" [MeSH Terms] OR \"nose\" [All Fields] OR \"nasal\" [All Fields]) AND (\"oxygen\" [MeSH Terms] OR \"oxygen\" [All Fields])) AND \"humans\" [MeSH Terms])

Search Outcome

117 studies identified. 14 clinical studies reviewed of which 5 were relevant to the question.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Sztrymf et al. September 2011, France.	38 adult patients admitted to intensive care with acute respiratory failure, defined as requiring more than 9 l/min oxygen to achieve an SpO2 > 92% or exhibiting persistent signs of respiratory distress (respiratory rate > 25 bpm, thoraco-abdominal asynchrony or supraclavicular retraction) despite oxygen administration. Patients requiring immediate endotracheal intubation or with hypercapnic respiratory failure were excluded.	Prospective, observational study. High flow, humidified nasal oxygen therapy compared to conventional oxygen therapy (delivered by non-rebreathing face mask).	PaO2 after 1h of high flow nasal oxygen	Significantly increased (p=0.009)	No control, small study.
			Respiratory rate on high flow nasal oxygen (all time points from 15 minutes to 48h)	Significantly decreased (p=0.009)
			Dyspnoea on high flow nasal oxygen (all time points from 15 minutes to 48h)	Significantly decreased (p=0.012)
			Tolerance of therapy	No patients required cessation of therapy because of intolerance
Lenglet et al. November 2012, France.	17 adult patients admitted to the emergency department with acute respiratory failure, defined as requiring ore than 9l/min oxygen or ongoing signs of respiratory distress despite oxygen therapy.	Prospective, observational, feasibilty study.	SpO2 after 15 minutes of high flow nasal oxygen	Significantly increased (p<0.0001)	No control, small study.
			Respiratory rate after 15 minutes of high flow nasal oxygen	Significantly decreased (p<0.0001)
			Dyspnoea intensity after 15, 30 and 45 minutes of high flow nasal oxygen (Borg score and VAS)	Significantly decreased (p< 0.05)
Parke et al. March 2011, New Zealand.	60 adult patients admitted to intensive care with hypoxaemic respiratory failure. Patients requiring immediate endotracheal intubation and those not for mechanical ventilation were excluded.	Prospective, randomised, controlled trial.	Desaturations	Significantly fewer in group receiving high flow nasal oxygen (p=0.009)	Unclear how hypoxaemic respiratory failure was defined. Mixed aetiologies including post-operative patients. Blinding not possible. Unclear how to power such studies given effect size unknown.
			Respiratory rate	No significant difference
			PaO2 / FiO2	No significant difference
			Length of intensive care stay	No significant difference
			Length of hospital stay	No significant difference
Cuquemelle et al. October 2012, France.	37 adult patients admitted to intensive care with acute hypoxaemic respiratory failure, defined as requiring at least 4l/min oxygen to maintain an SpO2 above 95%. patients requiring non-invasive or invasive ventilation were excluded.	Prospective, randomized, crossover design, single centre. High flow, humidified nasal oxygen compared to standard oxygen therapy (not humidifed, delivered by mask or nasal cannulae).	Mouth, nose and throat dryness score after 24 hours on high flow nasal oxygen	Significantly reduced (p=0.004)	Soft endpoints.
			Preferred oxygen delivery device	Significantly more people preferred high flow nasal oxygen (p=0.01)
Roca et al. April 2010, Spain.	20 adult patients admitted to intensive care with acute respiratory failure, defined as SpO2 < 96% while receiving humidified oxygen via facemask with an FiO2 greater than or equal to 0.5. Patients with an unstable clinical state, need for endotracheal intubation, decreased consciousness, haemodynamic instability despite fluid therapy and vasopressors, severe failure of > 2 organs apart from respiratory failure, pregnancy or lack of co-operation were excluded.	Prospective, observational study. High flow, humidified nasal oxygen compared to the preceding period of conventional oxygen therapy (delivered by facemask or nasal cannulae).	PaO2 after 30 minutes on high flow nasal oxygen	Significantly increased (p=0.002)	No control, small study.
			SpO2 after 30 minutes on high flow nasal oxygen	Significantly increased (p=0.02)
			Respiratory rate after 30 minutes on high flow nasal oxygen	Significantly decreased (p<0.001)
			Dyspnea after 30 minutes on high flow nasal oxygen	Significantly reduced (p=0.01)
			Mouth dryness after 30 minutes on high flow nasal oxygen	Significantly reduced (p<0.01)

Comment(s)

These studies are all small and predominantly observational in nature. In several cases the authors state that their observational study will be followed by a larger, randomised, controlled trial. Thus it seems likely that more robust evidence pertaining to this therapy may become available over the next couple of years. It must also be remembered that these studies do not compare high flow nasal oxygen to CPAP, non-invasive ventilation or invasive ventilation. There are other studies that examine the use of high flow nasal oxygen to improve oxygenation in differing patient groups e.g. post-operative patients or those undergoing procedures under sedation. It is of note that many studies of high flow nasal oxygen therapy comment on the perceived high tolerability of the therapy.

Clinical Bottom Line

The current available evidence suggests that high flow nasal oxygen results in improved oxygenation and respiratory parameters in comparison to oxygen delivered via face mask in adults with acute respiratory failure.

References

1. Sztrymf B, Messika J, Bertrand F, Hurel D, Leon R, Dreyfuss D, Ricard J. Beneficial effects of humidified high flow nasal oxygen in critical care patients: a prospective pilot study. Intensive Care Medicine 2011; 37: 1780-1786.
2. Lenglet H, Sztrymf B, Leroy C, Brun P, Dreyfuss D, Ricard J. Humidified high flow nasal oxygen during respiratory failure in the emergencey department: feasibility and efficacy. Respiratory Care. November 2012; 57 (11) : 1873-1878.
3. Parke R, McGuinness SP, Eccleston RN. A Preliminary Randomized Controlled Trial to Assess Effectiveness of Nasal High-Flow Oxygen in Intensive Care Patients. Respiratory Care. March 2011; 56 (3): 265 - 270.
4. Cuquemelle E, Pham T, Papon J, Louis B, Danin P, Brochard L. Heated and Humidified High-Flow Oxygen Therapy Reduces Discomfort During Hypoxemic Respiratory Failure. Respiratory Care. October 2012; 57 (10): 1571 - 1577.
5. Roca O, Riera J, Torres F, Masclans JR. High-Flow Oxygen Therapy in Acute Respiratory Failure. Respiratory Care. April 2010; 55 (4): 408 - 413.
6. Yin M, Shen H. Does the humidified high-flow nasal oxygen therapy decrease need for intubation in the acute respiratory failure adult patient?. Chinese Critical Care Medicine 2012; 24 (2): 68 - 69.