The Relation between Role of Serum Cortisol Level and Response to Various Respiratory Support Strategies among Preterm Infants

Introduction: Preterm infants are liable to various health problems including respiratory distress syndrome (RDS). There is variation in response to respiratory support. In preterm infants, cortisol hormone is secreted by the adrenocortical gland in response to stress. Objectives: To compare the serum cortisol levels in blood among preterm infants who needed different respiratory support strategies e.g. headbox, continuous positive airway pressure (CPAP), intubation surfactant extubation (INSURE) and mechanical ventilation (MV) and to correlate the cortisol levels to the severity of respiratory distress syndrome (RDS). Material and Methods: Observational prospective study that assessed the serum cortisol levels in preterm infants with RDS after initial respiratory support aged 28 - 34 gestational weeks that were admitted to the neonatal intensive care unit of Al Zahraa hospital of Al-Azhar University and Al-Estekama hospital between February 2019 and November 2019. Infants were classified into three groups, Group 1: 29 infants with severe RDS who needed a mechanical ventilator. Ten of them needed surfactant therapy. Group 2: 33 infants with moderate RDS who needed CPAP. Three of them needed surfactant therapy. Group 3: 28 infants with symptoms of mild RDS who needed headbox. None of them needed surfactant therapy. Blood samples were collected on the first day of life and were processed using the colorimetric ELISA method. Demographic and medical information was collected. Results: A total of 90 preterm infants were included. The serum cortisol reference was 4.3 - 22.4 mg/dl. Group 1 showed significantly higher serum cortisol levels compared to group 2 and group 3 (39.22 ± 9.91 mg/dl vs 28.96 ± 6.48 mg/dl vs 25.88 ± 5.42 mg/dl) respectively, (P-value = 0.001). Infants in group 2 who needed surfactant therapy had higher serum cortisol levels than those who did not need surfactant therapy (32.30 ± 5.92 mg/dl vs 28.33 ± 6.27 mg/dl). The serum cortisol levels were observed having a negative correlation with gestational age and birth weight. No significant differences were observed in terms of gender or type of delivery. Conclusion: Cortisol levels had a positive correlation with the severity of RDS who needed various respiratory support strategies.