Clinical RD (Respiratory Distress) Score for Objective Decision Making for Surfactant Therapy

Respiratory distress syndrome, also known as hyaline membrane disease, occurs almost exclusively in premature infants. The incidence and severity of respiratory distress syndrome are inversely related to the gestational age of the newborn infant. The incidence of RDS is around 60 - 80% among infants \< 28 weeks, 30-40% between 28-34 weeks, less than 5% at 34 weeks and is rarely seen among those > 37 weeks.

The availability of continuous positive airway pressure (CPAP) and natural surfactant have revolutionised the management of RDS. In 1967, Gregory et al. reported the value of application of continuous positive airway pressure in the management of RDS. Successful surfactant replacement therapy in RDS was reported by Fujiwara et al. Besides the use of Continuous positive airway pressure and surfactant replacement, the other advances include: Use of antenatal steroids to enhance pulmonary maturity, appropriate resuscitation and immediate use of CPAP for alveolar recruitment, Use of gentler modes of ventilation like patient triggered ventilation, Supportive therapies, such as the diagnosis and management of patent ductus arteriosus (PDA), fluid and electrolyte management, trophic feeding and nutrition.

The use of CPAP applied to the alveoli has been shown to stabilise and improve respiratory distress in preterm babies. It preserves the action of endogenous surfactant and may also obviate the need for surfactant in a substantial number of cases. CPAP is cost effective and more patient friendly than mechanical ventilation. Availability of CPAP even at the district level Special Newborn Care Unit (SNCU) in various states across the country make it an ideal candidate for respiratory support in the high risk population.

In addition to optimal respiratory support in the form of continuous positive airway pressure (CPAP) or mechanical ventilation and good supportive care, surfactant replacement therapy (SRT) forms the mainstay in the management of RDS. Since the report by Fujiwara in 1980 of the first successful use of SRT, numerous randomized controlled trials (RCTs) and their meta-analyses have established its efficacy in reducing mortality and air leak syndromes in RDS. Almost all the trials evaluating the role of SRT were conducted in high-income countries. Not surprisingly, SRT is the standard of care in neonates with RDS in these countries.

The population in low and middle income countries (LMIC) like India may differ significantly from the western world. But whether the evidence from these high income countries can be extrapolated to LMICs, still remains questionable. High cost of surfactant therapy, issue regarding regular supply of the drug, lack of skilled personnel, poor antenatal steroid coverage of mothers with preterm labour, higher incidence of perinatal hypoxia/ischemia and infections all complicate the clinical course of RDS. The paucity of evidence for efficacy and/ or safety of SRT in these settings further add to the complexity.

Continuous positive airway pressure (CPAP) remains as the first line of respiratory support in spontaneously breathing infants with RDS and surfactant is administered if required. The beneficial effects of surfactant are more pronounced when the therapy is started earlier. In most of the units across the country, the decision to administer surfactant to such babies managed on CPAP is clinician oriented and hence remains highly subjective. There are no objective criteria to decide for administration of surfactant to infants who are initially managed with CPAP. The current study was planned keeping in mind the beneficial effects of early CPAP and early surfactant, with the aim of developing an objective scoring system, which would guide the clinician in decision making for administration of surfactant to infants with RDS who are already being managed with CPAP.