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The use of nasal continuous positive airway pressure (NCPAP) is a well-accepted strategy for treating respiratory distress syndrome (RDS) in premature neonates. This approach has been used as the primary treatment for RDS even in very low birth-weight infants, with outcomes comparable to those who are intubated, receive surfactant, and are mechanically ventilated.1 Providing supplemental oxygen
and/or distending airway pressure to the smallest of newborns presents a number of physiologic and technological challenges that are rarely, if ever, present in adult patients. Physiologically, for almost 60 years, it has been known that a sustained arterial oxygen partial pressure >80 mm Hg is associated with the increased risk for development of retinopathy of prematurity.2,3 In addition, exposure to high positive airway pressure can cause lung injury.4 Balancing the need to supply supplemental oxygen and pressure with the need to provide the appropriate amount of oxygen to a neonate who may weigh <1000 grams presents a technological challenge that caregivers have been
attempting to resolve since the early 1970s.5
A number of noninvasive NCPAP delivery devices developed since the late 1980s have been widely used to treat premature infants with RDS.6 Most of these devices have been variations on the original design by Kattwinkel and colleagues.7 Consequently, all of the interfaces developed and used today for delivery of NCPAP to newborns share well-known drawbacks, including difficulty
keeping the interface in place, difficulty maintaining a seal, obstructive nasal secretions, injury to the nasal mucosa, septal trauma, nasal trauma, and such chronic problems as nasal deformities.8,9 Because these difficulties are encountered in nearly every NICU providing NCPAP to premature newborns, caregivers have moved very quickly toward what some view as an alternative way of delivering
NCPAP — that is, via the heated, humidified high-flow nasal cannula (HFNC/HHHFNC).
HFNC therapy was introduced into the clinical setting to reduce some of the more severe complications associated with the use of traditional NCPAP therapy, as well as to prevent dryness of the nasal mucosa by heating and humidifying the inhaled gas to near body temperature and near 100% relative humidity.10 The advantage of these devices stems from their ease of administration
compared with the apparatus required to set up NCPAP, reduction in patient device interface problems, and the expectation that patient outcomes will be equivalent or better than those reported with the use of traditional NCPAP.
Although HFNC therapy appears to be becoming increasingly popular in NICUs, randomized controlled trials are not available to help guide therapy. Two of the key concerns regarding the use of HFNC therapy in the neonatal population are: 1) that no standard exists for measuring pressure delivery (CPAP-generated) when an HFNC is being used; and 2) the potential for increased risk
for infection with the use of HFNC devices.
To date, the few published studies on the subject demonstrate that HFNC therapy is well tolerated, with few adverse events. Patient outcomes are similar to those described with the use of NCPAP.11-13 However, lack of pressure monitoring is a well-known limitation of HFNC therapy. Unlike conventional NCPAP therapy, in which an infant breathes from a pressurized circuit, flow
from the HFNC is directed entirely into the nasopharynx, with the only escape routes being the mouth, nose, and esophagus. In 1993, Locke and associates demonstrated that the use of nasal cannulas with high flow rates in newborns can result in the administration of inadvertent positive end-expiratory distending pressure, leading to an altered breathing strategy.14 In an in vitro evaluation,
Lampland and coworkers demonstrated that when no leak is present within the HFNC circuit, the pressure generated by the HFNC system can rise to a level that can rupture the humidifier.15 Although the outcome with a perfect seal is dramatic, obtaining a perfect seal in the clinical setting is unlikely. However, problems due to high pressure in the clinical setting (eg, barotrauma) may be evident
long before a perfect seal has been obtained. A number of studies have shown that the pressure generated by the HFNC system in the clinical setting is directly related to the leak present at the nares and the mouth.16,17 The magnitude of the leak is related to the size of the cannula, the neonate’s nares, and whether the infant’s mouth is opened or closed.15-17 Virtually all of the published
reports demonstrating favorable outcomes related to HFNC use have examined neonates weighing >800 grams. However, neonates weighing <800 grams may be more likely to be intubated, making it easy to understand the attractiveness of the apparently less complex application associated with the use of HFNC devices. Because of the small nares in such neonates, a smaller leak is to be expected between the cannula and the nares, which may result in higher pressures being delivered.
In addition to the concern regarding unpredictable pressure delivery noted above, several reports raise concern for a risk for infection with high-flow nasal cannula use.13,18 One device was recalled because of concerns over colonization with Ralstonia pickettii, but it has since been placed back on the market.19 HFNC systems may provide CPAP; therefore the correlation between
late-onset gram-negative blood infections and the use of CPAP described by Graham and colleagues18 is of particular importance. The authors suggested 3 possible reasons for the late-onset Gram-negative blood infections: nasal mucosal damage as a portal of entry for infectious organisms; frequent invasive nasal suctioning with contaminated equipment, hands, or the environment; and introduction of
Gram-negative organisms via translocation from the intestinal tract of an infant with gastric distention as a result of exposure to continuous positive airway pressure. Although newer NCPAP and HFNC devices seem to be better able to maintain normal mucosa than previous high-flow cannula systems,12 and infection control practices are continually scrutinized, it remains to be seen if infection
rates among premature neonates will be altered — a relationship that warrants further investigation.
Because of the potential problems related to barotrauma with the use of HFNCs, newly developed HFNC devices should, ideally, incorporate a pressure measurement mechanism to both improve awareness of possible impending problems and facilitate the clinician’s ability to render sound judgment regarding supplemental oxygen therapy for the patient. In the absence of an integrated pressure monitoring
system within the HFNC, it may be prudent to select equipment that allows for a substantial leak around the nares. This can be achieved by using the smallest acceptable nasal cannula on the smallest of neonates. Because of the possible infectious risks associated with the use of high-flow nasal cannulas, it may also be important to maintain an adequately structured infection control and
surveillance program. Data obtained from such a program would, as necessary, allow for rapid practice changes.
Commentary References
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Morley CJ, Davis PG, Doyle LW, Brion LP, Hascoet JM, Carlin JB; COIN Trial Investigators. Nasal CPAP or intubation at birth for very preterm infants. N Engl J Med. 008;358(7):700-708.
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Studies on the effect of high oxygen administration in retrolental fibroplasia. I. Nursery observations. Am J Ophthalmol.
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A cohort study of transcutaneous oxygen tension and the incidence and severity of retinopathy of prematurity. N Engl J Med. 1992;326(16):1050-1054. |
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Jobe AH, Ikegami M.
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Gregory GA, Kitterman JA, Phibbs RH, Tooley WH, Hamilton WK. Treatment of the idiopathic respiratory-distress syndrome with continuous positive airway pressure. N Engl J Med.
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De Paoli AG, Morley CJ, Davis PG, Lau R, Hingeley E.
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2002;87(1):F42-F45. |
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Kattwinkel J, Fleming D, Cha CC, Fanaroff AA, Klaus MH. A device for administration of continuous positive airway pressure by the nasal route. Pediatrics.
1973;52(1):131-134. |
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Yong SC, Chen SJ, Boo NY.
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Waugh JB, Granger WM.
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Saslow JG, Aghai ZH, Nakhla TA, Hart JJ, Lawrysh R, Stahl GE, et al.
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Woodhead DD, Lambert DK, Clark JM, Christensen RD.
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Shoemaker MT, Pierce MR, Yoder BA, DiGeronimo RJ.
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Locke RG, Wolfson MR, Shaffer TH, Rubenstein SD, Greenspan JS.
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Lampland AL, Plumm B, Meyers PA, Worwa CT, Mammel MC.
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Kahn DJ, Courtney SE, Steele AM, Habib RH.
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Graham PL III, Begg MD, Larson E, Della-Latta P, Allen A, Saiman L. Risk factors for late onset gram-negative sepsis in low birth weight infants hospitalized in the neonatal intensive care unit. Pediatr Infect Dis J. 2006;25(2):113-117.
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