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Three Part Question

In [inhalational/airway burns] does [humidified compared to high flow/non-rebreathe oxygen therapy] improve [patient comfort and/or oxygenation]?

Clinical Scenario

You are the emergency department duty doctor for resus, and an ambulance pre-alert is given for a patient with potential airway burns from a house fire. Whilst preparing for patient arrival, a non-rebreathe mask is set up, but a colleague suggests using high flow (>15lpm) humidified oxygen therapy which isn’t immediately available in your department. You consider whether this should be used as first line treatment?

Search Strategy

EMBASE, PubMed and CINAHL were searched, with no limitation on date or language, via the NICE Healthcare Databases Advanced Search portal, search strategy 445811.
Clinicaltrials.gov with a simpler search strategy.
585 search results for "((burn* OR smok*) AND (inhal* OR airway*)).ti,ab AND ((humid* OR nebul* OR (hi* AND flo*) OR rebreath* OR mask OR aerosol*) AND oxygen*).ti,ab" as of 20th June 2018.

Clinicaltrials.gov searched for ‘hi flow’ or ‘humidified’.

Search Outcome

CINAHL: 28, Medline: 168, PubMed: 24 and EMBASE: 365 results
Total: 585 results, with 200 duplicated. After removal of these, 245 articles screened, using the Rayyan platform (1), based on title or abstract with regard to the three part question. No articles were directly relevant.

Clinicaltrials.gov: 139 results for ‘humidified’ had no directly relevant trials, however NCT03326830 (PRHOXY-1) is a currently recruiting trial for comparing high flow nasal oxygen (HFNO) with standard oxygen therapy in the pre hospital environment (specifically Airvo2 device). A handful of trials examine use of HFNO in acute hypoxic respiratory failure, which may include the intended group of patients.

1479 results for high flow, with one trial NCT03342209 having investigated the ‘Utility of High Flow Nasal Cannula in CO Toxicity’ but have not published yet.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Foncerrada et al 2018 USA	N/A	Review article		No consensus exists regarding the diagnosis, grading, and prognosis of inhalation injury. Recommendation of: Nebulise 20% N-acetylcysteine (3 mL) every 4 h for 7 d (with bronchodilator cover due to irritant effects) Alternate aerosolizing 10,000 U of heparin (in 3 mL normal saline) every 4 h for 7 d Salbutamol nebulisers for wheezing
Kessler et al 2015 USA	Single patient, exposed to fluoride gas from a glass etching cream	Case Report (3)	Symptom resolution (temporary/sustained) - inferrred	Patient had 4 treatments with nebulised 2.5% calcium gluconate, with improvement in pain, dyspnoea and other symptoms. No mention of advanced airway management being required.	Case Report, from Conference Proceedings (Abstract) Original paper not found.

Comment(s)

None of the papers discussed the use of the high flow nasal oxygen in acute inhalation injury. Much of the identified literature discussed the use of humidified oxygen, however this is likely to refer to conventional methods and does not specify type of device used. Whilst not the focus of this BestBET, many animal and human articles discuss or trial the use of novel agents to limit pulmonary injury and readily available agents such as adrenaline and budesonide.

Clinical Bottom Line

There is currently no reported use of high flow humidified oxygen therapy in patients with inhalation injury. There are trials regarding it’s use prehospitally and in carbon monoxide toxicity. It’s use is already established in the critical care environment and provides higher flow rates than wall oxygen with the additional benefit of humidification. As a device not currently available prehospitally, ambulance services may wish to consider use of humidified flow meters as a means of providing non-electricity based humidification at flow rates up to 15lpm. This may also be a used in hospital where high flow (>15lpm) humidified oxygen is not available. References 1. Ouzzani M, Hammady H, Fedorowicz Z, Elmagarmid A. Rayyan-a web and mobile app for systematic reviews. Syst Rev [Internet]. 2016;5(1):1–10. Available from: http://dx.doi.org/10.1186/s13643-016-0384-4

Level of Evidence

Level 3 - Small numbers of small studies or great heterogeneity or very different population.

References

1. Foncerrada, Guillermo Culnan, Derek M. Capek, Karel D. González-Trejo, Sagrario Cambiaso-Daniel, Janos Woodson, Lee C. Herndon, David N. Finnerty, Celeste C. Lee, Jong O. Inhalation Injury in the Burned Patient Annals of Plastic Surgery 2018; S98 -105
2. Kessler B, Nitsche D, Calandrella C and Nogar J Acute dyspnea and pharyngeal irritation after inhalation of fumes from a concentrated fluoride-containing etching cream Clinical Toxicology 2015; 743