How does NHF therapy work?

NHF is a flow-based therapy designed to be an open system that typically consists of a flow source to blend air and oxygen, a humidifier to heat and humidify the gas mixture and a circuit and interface to deliver humidified gas to the patient. Suitable sizing of the nasal cannula is important to ensure an open system is maintained.

NHF is associated with a range of mechanisms of action and associated physiological benefits

physiological study by Milesi et al. 2013

Delivers dynamic positive airway pressure

With NHF, flow is prescribed and set. A level of dynamic positive airway pressure is generated as a result of the flow, which is dependent on a range of factors such as the weight of the infant, the set flow rate, and nare occlusion.⁴

It is therefore important to ensure that the nasal cannula does not create a seal in the nares, thus maintaining NHF as an open system.

The dynamic positive airway pressure associated with NHF has been shown to reduce inspiratory effort and work of breathing compared to standard oxygen therapy.^5-7 Work of breathing is the force required to expand the lungs against their elastic properties.

Promotes airway hydration

NHF delivers a heated and humidified blend of air and oxygen, maintaining the nasal mucosa and enhancing mucociliary function.⁸

NHF reduces mucosal dryness and injury, and improves secretion clearance compared to standard oxygen therapy.⁹ Consensus guidelines state that NHF should always be adequately heated and humidified.^10,11

Learn more about humidity

Supplemental oxygen

NHF differs from standard oxygen therapy in that it can accurately deliver a prescribed FiO₂ when the set flow rate meets or exceeds a patient’s peak inspiratory demand.^12,13

FiO₂ is the proportion of oxygen in the air that is inspired.¹³ In addition to the ability to deliver accurate FiO₂, the combined mechanisms of NHF has the effect of improving oxygenation status.^14-16

Improves patient comfort

As NHF is an open system, it is gentle on the nose.

Compared to continous positive airway pressure, NHF improves patient comfort, compliance, and tolerance to therapy.^17,18 NHF is also associated with a significant reduction to rates of nasal trauma.^19-20

To assess patient comfort, studies have used objective measures such as heart rate, facial expressions, and movement.¹⁸

Evidence-based applications for NHF

There is a well-established evidence base that describes how NHF can be used to support the patient pathway through the hospital.
Learn more about the applications of NHF for different patient populations.

Neonates

Learn more about using NHF therapy for treating neonates

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Infants and Children

Learn more about using NHF therapy for treating infants and children

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Dysart, K., Miller, T. L., Wolfson, M. R. & Shaffer, T. H. Research in high-flow therapy: mechanisms of action. Respir. Med. 103, 1400–1405 (2009). View abstract here.
Mascoll-Robertson, K. K., Viscardi, R. M., & Woo, H. C. The objective use of pulse oximetry to predict respiratory support transition in preterm infants: an observational pilot study. Respir. Care 61, 416–422 (2016). View abstract here.
Kubicka, Z. et al. Heated, humidified high-flow nasal cannula therapy: yet another way to deliver continuous positive airway pressure? Pediatrics 121, 82–88 (2008). View abstract here.
Saslow, J. et al. Work of breathing using high-flow nasal cannula in preterm infants. J. Perinatol. 26, 476–480 (2006). View abstract here.
Milési, C. et al. Is treatment with a high-flow nasal cannula effective in acute viral bronchiolitis? A physiologic study. Intensive Care Med 39, 1088–1094 (2013). View abstract here.
Shetty, S., Hickey, A., Rafferty, G., Peacock, J., & Greenough, A. Work of breathing during CPAP and heated humidified high-flow nasal cannula. Arch. Dis. Child Fetal Neonatal. Ed. 101, F404–407 (2016). View abstract here.
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El-Farghali, O. High-flow nasal cannula in neonates. Respir. Care 62, 641–642 (2017). View abstract here.
Al-Alaiyan, S., Dawoud, M., & Al-Hazzani, F. Positive distending pressure produced by heated, humidified high flow nasal cannula as compared to nasal continuous positive airway pressure in premature infants. J. Neonatal Perinat. Med. 7, 119–124 (2014). View abstract here.
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Sarkar, M. et al. Comparative study between noninvasive continuous positive airway pressure and hot humidified high-flow nasal cannulae as a mode of respiratory support in infants with acute bronchiolitis in pediatric intensive care unit of a tertiary care hospital. Indian J. Crit. Care Med. 22, 85–90 (2018). View abstract here.
Collins, C. L., Barfield, C., Horne, R. S. C., & Davis, P. G. A comparison of nasal trauma in preterm infants extubated to either heated humidified high-flow nasal cannulae or nasal continuous positive airway pressure. Eur. J. Pediatr. 173, 181–186 (2014). View abstract here.
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Yoder, B. et al. Heated, humidified high-flow nasal cannula versus nasal CPAP for respiratory support in neonates. Pediatrics 131, e1482–1490 (2013). View abstract here.
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