Comprehensive, noninvasive saturation, oxygen, and pressure index: Does it reflect the severity of acute respiratory illness in neonates on continuous positive airway pressure? a prospective study

Abstract

Background: The severity of respiratory illness in neonates on invasive ventilatory support is assessed by oxygenation index and alveolar–arterial oxygen gradient (A-aDO2). Both these parameters need arterial blood gas estimation which is an invasive procedure with attendant complications. Neonates with less severe respiratory disease are managed on continuous positive airway pressure (CPAP). The progress of the disease is generally assessed by noting the changes in FiO2and positive end-expiratory pressure (PEEP) provided. Blood gas analysis is done for objectively assess the babies who progress to more severe disease. A noninvasive tool such as saturation, oxygen, and pressure index (SOPI) helps in reducing the need for invasive blood gas estimation. A good correlation of SOPI with A-aDO2can provide near-continuous bedside assessment of the respiratory disease. Objective: To determine the correlation between SOPI and A-aDO2. Materials and Methods: All babies admitted to our neonatal unit requiring CPAP were considered eligible for this study. The adjustments in FiO2, CPAP pressures, and arterial blood gas were done as per unit protocol. A-aDO2was calculated. SOPI was calculated as (PEEP × FiO2)/SpO2. The two values were then correlated. Results: Seventy-five babies were recruited. SOPI correlated positively (r = 0.847) with A-aDO2(P