The Journal of Pediatrics
Volume 154, Issue 2 , Pages 160-162, February 2009

High-Flow Nasal Cannula: A Kinder, Gentler CPAP?

  • Neil N. Finer, MD

      Affiliations

    • Professor of Pediatrics
    • Corresponding Author InformationReprint requests: Neil N. Finer, Professor of Pediatrics, Division of Neonatology, UCSD Medical Center and School of Medicine, 402 Dickinson St, MPF 1-140, San Diego, CA 92103-8774
    • ,
  • Frank L. Mannino, MD

      Affiliations

    • Professor of PediatricsDivision of NeonatologyUniversity of California San Diego Medical Center and School of MedicineSan Diego, California

Article Outline

Abbreviations: CPAP, Continuous positive airway pressure, EEEP, End expiratory esophageal pressures, HFNC, High-flow nasal cannula

 

In this issue of The Journal, Lampland et al describe their observations comparing high-flow nasal cannula (HFNC) with traditional ventilator-derived continuous positive airway pressure (CPAP) for preterm infants.1 They reported that pressure increased with flow in their in vitro system and that the presence of a leak as low as 30% reduced such pressures to <3 cm H2O. They also noted an increasing RR in the infants receiving high flow nasal cannula (HFNC), as flow decreased from 6 lpm to 2 lpm.

See related article, p 177

Although the use of HFNC may seem like an attractive approach that would conceivably avoid trauma to the nose by using the smaller nasal cannula compared with most nasal CPAP interfaces, there are a number of concerns, including desiccation of the nasal mucosa with associated bleeding2 and airway obstruction3 when using non-humidified HFNC. However, as we have pointed out previously,4 the use of HFNC to deliver CPAP is problematic because the users generally have no knowledge of the actual level of CPAP delivered to the infant, and current delivery systems may not prevent excessive pressure delivery to the infants' airway, which may result in significant lung overexpansion.5 Sreenan et al pointed out that adequate pressure delivery required maintenance of “a good seal in the oral cavity,”6 consistent with earlier observations that there is a dramatic fall in pressure from cannula to pharynx that is aggravated when the mouth is open, as shown for CPAP.7 Sreenan et al studied HFNC with as much as 2.5 lpm to produce CPAP of 6 cm H2O, as measured by equivalent esophageal pressures (4.5-4.6 cm H2O), and reported that 6 hours of such treatment was equivalent to 6 hours of traditional CPAP for the treatment of apnea in 28-week-old infants at 30 weeks post-conception age.6 Their calculations would indicate that a flow of 1.6 lpm in an infant weighing 1000 gm and 1.3 lpm for an infant weighing 500 gm with similar cannula would produce 6 cm H2O CPAP.

Lampland et al used a nasal prong and humidified delivery system to deliver HFNC. Even with flows of 6 lpm and with infants' mouths closed, this study did not produce an esophageal pressure equivalent to that seen with 6 cm H2O of conventional CPAP. Their measured end expiratory esophageal pressures (EEEP) using a fluid-filled catheter were lower than those reported by Sreenan et al using an esophageal balloon. These methods may not produce identical results, and both are difficult to use in a clinical environment.

The authors demonstrated a trend of increasing EEEP with each liter increase in nasal cannula flow that was not significantly different from each separate flow measure or the EEEP seen with NCPAP at 6 cm H2O. Their Figure demonstrated that with increasing NC flow there was an increase in EEEP, but it was never equivalent to the 3.4 cm H2O at 6 cm H2O reported in their Table 1. They also noted very large variation in the EEEPs, suggesting that these measures are not clinically useful. Their mean EEEP was always <2 cm H2O for all flows <6 lpm, and for flows <3 lpm, they reported EEEPs <1 cm H2O. They did not find pressures similar to those reported by Sreenen et al (4.5 cm H2O at 6 cm H2O NCPAP), and this may reflect different measuring systems, nasal cannula size, and the duration of the measurements.

The use of a pressure-regulated source of CPAP, such as a ventilator or underwater seal, ensures that within narrow limits the delivered pressure will not exceed the set pressure, irrespective of the state of the airway. Even the use of nasal cannula oxygen with room air and flows as high as 2 lpm is of some concern. The American Association of Respiratory Care 2002 Clinical Practice Guideline stated that maximum flow for nasal cannula in newborn infants should not exceed 2 lpm, a flow that may be excessive for the extremely low birth weight infant.8 Locke et al previously demonstrated that with flows of 2 lpm it was possible to deliver 12 cm H2O CPAP, dependent on infant and cannula size,9 and subsequently demonstrated that HFNC are associated with significantly higher upstream pressures.10 There are increasing reports that use HFNC as a form of respiratory support in preterm and term newborn infants,11, 12 with flows as high as 6 lpm,13 and these reports do not document the level of CPAP or overall patient benefit.

Although it is unclear what the optimal level of CPAP is for any individual infant, earlier studies in infants with respiratory distress syndrome have suggested that this value is close to 8 cm H2O, with significant interpatient variability.14, 15

The airway pressure delivered using a high-flow gas source will vary with the presence of leaks within the airway. When these are always constant, the actual pressure may be predictable. However, such conditions seldom exist in the preterm infant. Thus, when the infant closes the mouth and there are dried secretions around the nares that essentially occlude the nose around the catheter tips, the flow will continue to increase the pressure until either the airway opens or the air under pressure can escape somewhere else. One would hope that that the natural airway orifices would be the first to give!

There are few routine clinical evaluations that can detect an over-expanded lung, and even daily chest radiography may not provide timely information about such a problem before the occurrence of an air leak. It is somewhat reassuring that retrospective reviews of the use of HFNC with flows as high as 8 lpm have not demonstrated significant morbidity, except for the observation of increased gram-negative infections.16 However, it would be more reassuring if the caregivers actually measured the esophageal pressure with their typical devices and a range of flows to ensure that they are not potentially over-distending the lung. It may be that the use of HFNC with very low effective pressures may be an advantage compared with CPAP, because infants may not require such treatment, and the potential benefit of HFNC is that it reduces infants' exposure to measurable CPAP levels. It would appear that the use of nasal cannula with a pressure-regulated supply could reduce the likelihood of inadvertent over-distension, and at the same time, such devices will reduce the likelihood of providing significant CPAP to infants who no longer need such therapy. We agree with Lampland et al on the need for a properly powered prospective randomized trial comparing HFNC with known pressure delivery (if possible) and current methods of delivering CPAP and which evaluates important outcomes to properly determine the safe and effective use of HFNC.

Back to Article Outline

References 

  1. Lampland LL, Plumm B, Meyers PA, Worwa CT, Mammel MC. Observational study of humidified high flow nasal cannula compared with nasal continuous positive airway pressure. J Pediatr. 2009;154:177–182
  2. Kopelman AE, Holbert D. Use of oxygen cannulas in extremely low birthweight infants is associated with mucosal trauma and bleeding, and possibly with coagulase-negative staphylococcal sepsis. J Perinatol. 2003;23:94–97
  3. Kopelman AE. Airway obstruction in two extremely low birthweight infants treated with oxygen cannulas. J Perinatol. 2003;23:164–165
  4. Finer NN. Nasal cannula use in the preterm infant: oxygen or pressure?. Pediatrics. 2005;116:1216–1217
  5. Courtney SE, Pyon KH, Saslow JG, Arnold GK, Pandit PB, Habib RH. Lung recruitment and breathing pattern during variable versus continuous flow nasal continuous positive airway pressure in premature infants: an evaluation of three devices. Pediatrics. 2001;107:304–308
  6. Sreenan C, Lemke RP, HudsonMason A, Osiovich H. High-flow nasal cannulae in the management of apnea of prematurity: a comparison with conventional nasal continuous positive airway pressure. Pediatrics. 2001;107:1081–1083
  7. DePaoli AG, Lau R, Davis PG, Morley CJ. Pharyngeal pressure in preterm infants receiving nasal continuous positive airway pressure. Arch Dis Child. 2005;90:F79–F81
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  9. Locke RG, Wolfson MR, Shaffer TH, Rubenstein SD, Greenspan JS. Inadvertent administration of positive end-distending pressure during nasal cannula flow. Pediatrics. 1993;91:135–138
  10. Chang GY, Cox CC, Shaffe TH. [1231] Nasal Cannula, CPAP and vapotherm: effect of flow on temperature, humidity, pressure and resistance. Pediatr Acad Soc. 2005;57:1231
  11. Quinn D. Nasal cannula treatment for apnea of prematurity. Pediatr Acad Soc. 2005;57:1248
  12. Ovalle OO, Gomez T, Troncoso C, Palacios J, Ortiz E. High flow nasal cannula after surfactant treatment for infant respiratory distress syndrome in preterm infants <30 Wweks. Pediatr Acad Soc. 2005;57:3417
  13. Ramanathan A, Cayabyab R, Sardesai S, Siassi B, Seri I, Ramanathan R. High flow nasal cannula use in preterm and term newborns admitted to neonatal intensive care unit: a prospective, observational study. Pediatr Acad Soc. 2005;57:3424
  14. Bonta BW, Uauy R, Warshaw JB, Motoyama EK. Determination of optimal continuous positive airway pressure for the treatment of IRDS by measurement of esophageal pressure. J Pediatr. 1977;91:449–454
  15. Landers S, Hansen TN, Corbet AJ, Stevener MJ, Rudolph AJ. Optimal constant positive airway pressure assessed by arterial alveolar difference for CO2 in hyaline membrane disease. Pediatr Res. 1986;20:884–889
  16. Shoemaker MT, Pierce MR, Yoder BA, DiGeronimo RJ. High flow nasal cannula versus nasal CPAP for neonatal respiratory disease: a retrospective study. J Perinatol. 2007;27:85–91

PII: S0022-3476(08)00698-7

doi:10.1016/j.jpeds.2008.08.021

Refers to article:

  • Observational Study of Humidified High-Flow Nasal Cannula Compared with Nasal Continuous Positive Airway Pressure , 01 September 2008

    Andrea L. Lampland, Brenda Plumm, Patricia A. Meyers, Cathy T. Worwa, Mark C. Mammel
    The Journal of Pediatrics February 2009 (Vol. 154, Issue 2, Pages 177-182.e2)

The Journal of Pediatrics
Volume 154, Issue 2 , Pages 160-162, February 2009

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