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High-flow therapy: physiological effects and clinical applications

Research output: Contribution to journalArticlepeer-review

Original languageEnglish
Article number200224
Pages (from-to)1-10
Number of pages10
Issue number4
Published1 Dec 2020

Bibliographical note

Funding Information: R.F. D’Cruz has nothing to disclose. N. Hart reports grants from Philips-Respironics (OPIP Trial, unrestricted research grant), RESMED (HoT-HMV Trial, unrestricted research grant) and Philips-Respironics (HoT-HMV Trial, unrestricted research grant), non-financial support from Philips-Respironics RT Meeting (development of MYOTRACE technology), outside the submitted work. In addition, Prof. Hart has a European patent for MYOTRACE issued, and a US patent for MYOTRACE pending. Prof. Hart’s research group has received unrestricted grants (managed by Guy’s & St Thomas’ Foundation Trust) from Philips and Resmed. Philips are contributing to the development of the MYOTRACE technology. G. Kaltsakas has nothing to disclose. Publisher Copyright: © ERS 2021. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

King's Authors


Humidified high-flow therapy (HFT) is a noninvasive respiratory therapy, typically delivered through a nasal cannula interface, which delivers a stable fraction of inspired oxygen (FIO2) at flow rates of up to 60 L·min−1. It is well-tolerated, simple to set up and ideally applied at 37°C to permit optimal humidification of inspired gas. Flow rate and FIO2 should be selected based on patients’ inspiratory effort and severity of hypoxaemia. HFT yields beneficial physiological effects, including improved mucociliary clearance, enhanced dead space washout and optimisation of pulmonary mechanics. Robust evidence supports its application in the critical care setting (treatment of acute hypoxaemic respiratory failure and prevention of post-extubation respiratory failure) and emerging data supports HFT use during bronchoscopy, intubation and breaks from noninvasive ventilation or continuous positive airway pressure. There are limited data on HFT use in patients with hypercapnic respiratory failure, as an adjunct to pulmonary rehabilitation and in the palliative care setting, and further research is needed to validate the findings of small studies. The COVID-19 pandemic raises questions regarding HFT efficacy in COVID-19-related hypoxaemic respiratory failure and concerns regarding aerosolisation of respiratory droplets. Clinical trials are ongoing and healthcare professionals should implement strict precautions to mitigate the risk of nosocomial transmission.

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