CPAP and respiratory management in premature infants

Treatment of respiratory distress syndrome (RDS) in low birth weight infants (LBWI) infants involves surfactant administration and mechanical ventilation. Mechanical ventilation requires prolonged invasive intubation, which may be associated with physical damage, barotrauma or volutrauma. Moreover, these two factors can result in bronchopulmonary dysplasia (BPD). Therefore, minimally invasive ventilation is beneficial in managing LBWI with RDS. It has been shown that the only variable responsible for improved morbidity is the initiation of continuous positive airway pressure (CPAP). With CPAP, it is possible to maintain an open airway, to prevent lung collapse, and to establish functional residual capacity. CPAP can also reduce the incidence of morbidities associated with intermittent mandatory ventilation.
CPAP systems is composed of three basic parts: 1) a supply of heated and humidified air; 2) a patient interface (nasal cannula, face mask, or head hood); 3) an expiratory valve to provide positive air pressure. The heart of the CPAP system is the expiratory “positive pressure” valve, which can be a variable pressure-flow valve or a threshold resistor: the former provides a constant level of resistance to air flow, letting pressure fluctuating during spontaneous breathing, while the latter provide a constant level of pressure, allowing a more stable flow.
The evidence from randomized trials suggests that clinical outcomes are improved with early intubation and surfactant therapy followed by extubation to CPAP. Moreover, CPAP is indicated as a therapeutic intervention in infants with low functional residual capacity, or in patients with RDS, and is useful in the treatment of transient tachypnea, apnea, BPD and respiratory support after extubation.
Trial evidence has indicated that optimal management of LBWI consists of early treatment with surfactant, followed by extubation and stabilization on CPAP. In fact, results from a randomized trial conducted in LWBI with RDS showed the significant benefit with surfactant therapy followed by nasal CPAP over nasal CPAP alone. In particular, infants who received early treatment had improved oxygenation, with oxygen tension difference increasing more than in late-treated infants. In addition, the need for mechanical ventilation before discharge was reduced. A meta-analysis evaluating the use of surfactant and rapid extubation to nasal CPAP (NCPAP) found that infants with RDS treated with early surfactant replacement therapy and NCPAP were less likely to need mechanical ventilation, and they were at lower risk for air leaks than infants treated with NCPAP and later surfactant therapy. The same results were confirmed in other trials and metanalysis, which demonstrate a synergistic effect between early surfactant administration and rapid extubation to nasal CPAP.
While CPAP is being incorporated into regular practice, research is proceeding to improve outcomes in LBWI with RDS. For instance, nasal intermittent positive pressure ventilation (NIPPV) has the same benefits of CPAP, while supplementing intermittent breaths from the ventilator in coordination with respiratory efforts by the infant. Preliminary results on this technique are promising, but larger studies are needed to confirm the benefits of NIPPV.
In conclusion, literature suggests that surfactant therapy with rapid extubation to CPAP reduces the need for mechanical ventilation. Based on these findings, neonatologists are currently conducting randomized prospective clinical trials to determine the optimal strategies for the management of neonatal RDS, with the long-term goal of reducing the incidence of chronic lung disease, and expecially BPD.

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