Infant flow CPAP versus high flow nasal cannula CPAP in preterm infants

Continuous positive airway pressure (CPAP) can prevent atelectasis, maximize lung functional capacity and recrute collapsed alveoli, therefore allowing an easier extubation. Moreover, in preterm infants, CPAP is associated to a reduction of the incidence of apneas and asynchronous breathing, and prevents reintubation following initial extubation. The Infant Flow system (IF-CPAP) is one of the most common forms of CPAP, based on a fluidic-flip design to facilitate gas flow. IF-CPAP decrease oxygen requirement, improve respiratory effort and prevent extubation failure in preterm infants, but could damage the nares of infants, causing discomfort and, rarely, long-term disfigurement. Recently, a simple nasal cannula has been shown to generate positive end-expiratory pressure (PEEP) in preterm infants, if gas flow is delivered at a high rate (1–2 L/min). The amount of distending pressure depends on the size of the cannula, flow rate and size of the infant. Some studies have suggested that this method of high flow CPAP (HF-CPAP) is comparable to Hudson nasal prong CPAP, and it is supposed to be both easy to administer and cheap.
On these basis, a Canadian group conducted a study to evaluate the feasibility of HF-CPAP in preventing extubation failure of preterm infants with birth weight ≤1250 g, compared to that of IF-CPAP.
Preterm infants were randomized to HF-CPAP  (n=20) or to IF-CPAP (n=20) at extubation. Primary outcome was incidence of reintubation within 7 days while secondary outcomes included change in oxygen use and frequency of apnea and bradycardias postextubation.
In total, 12 infants randomized to HF-CPAP required reintubation within 7 days, compared to 3 infants in the IF-CPAP group (relative risk=2.1). Moreover, 7 out of these 12 infants in the HF-CPAP group were reintubated within 48 hours, because of severe apnea or increased frequency of apneas. The IF-CPAP was also associated to a lower oxygen requirement after extubation and to a lower incidence of apnea and bradycardia. No nasal damage was observed in either group.
The resuts of this trial differ from that observed in previous ones, which suggested that HF-CPAP is equivalent to conventional forms of nasal CPAP. Therefore, since results of these analyses, the use of HF-CPAP has recently increased. However, recent reports have demonstrated side effects of high air flow through simple nasal cannula, such as drying and bleeding of the nasal mucosa, and airway obstruction. Findings from the Canadian study suggest that HF-CPAP probably should not be used as an equivalent form of CPAP in preterm infants, since it was associated with an increase in the number of extubation failures, higher oxygen use, and more apneas and bradycardias, if compared to IF-CPAP. In conclusion, HF-CPAP delivered by a nasal cannula failed to maintain extubation status among preterm infants ≤1250 g. Therefore, results suggested that this form of CPAP is not an effective alternative to conventional nasal continuous positive airway pressure. However, its use in other patients, such as older preterm infants, remains to be determined.

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