237 - Respiratory Severity Score Patterns by Birth Gestational Age among a Cohort of Extremely Preterm Infants

Publication Number: 237.6268

Patrick J. Peebles, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States; Michael R. Lasarev, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States; Scott O. Guthrie, Vanderbilt University School of Medicine, Jackson, TN, United States; Matthew M. Laughon, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States; Roberta Keller, UCSF Benioff Children's Hospital San Francisco, San Francisco, CA, United States; Dinushan Kaluarachchi, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States

Background: Extremely preterm infants often develop respiratory distress syndrome and require respiratory support to manage respiratory failure. Respiratory severity score (RSS) is the product of the mean airway pressure (MAP), on invasive or non-invasive positive pressure, and fraction of inspired oxygen (FiO2), delivered by the respiratory device. Among preterm infants, RSS has been used to predict mortality and the development of bronchopulmonary dysplasia. Little is known about the typical progression of RSS over time in this population.

Objective: To characterize the RSS over time stratified by birth gestational age in extremely preterm infants.

Design/Methods: Observational study using data from the Prematurity and Respiratory Outcomes Program (PROP) cohort; mode of ventilation, level of respiratory support, and FiO2 were recorded daily. Daily RSS was calculated or estimated (high flow nasal cannula or nasal cannula) as shown in Table 1. Patients who died prior to 36 weeks’ PMA had all computed RSS values set to “missing” during the week of death and after. Gestational age (GA) cohorts were defined by completed weeks of GA. Daily RSS for each neonate was averaged over the number of days by completed postmenstrual age (PMA) week. Linear quantile mixed models were used to estimate longitudinal profiles of the median weekly RSS for completed PMA to a maximum of 36 weeks’ post menstrual age. Models were fit separately for each of six GA cohorts (23–28 weeks completed GA).

Results: The analysis included data from 823 infants born between 23 0/7 and 28 6/7 weeks' gestation. Figure 1 shows profiles for the median of the weekly average RSS over time (for 23 –36 weeks completed PMA) colored according to their completed GA at time of birth. Figure 2 has each birth GA profile drawn separately with estimated 95% CIs for the median weekly RSS at each PMA.

Conclusion(s): RSS's both at birth and at corrected PMA were inversely related to birth GA; higher scores were observed among the more preterm infants. Among infants with a birth GA between 23-25 weeks, there was an increase in RSS within the first 2 weeks of life, followed by a gradual decrease over time. In contrast, RSS was highest in the first week of life for infants born at 26-28 weeks. These data could assist with parental counseling, and determine timing for clinical interventions and patient selection for interventional studies. RSS trends can also be used for future studies to predict short and long-term outcomes.

Table 1
Respiratory Severity Score (RSS) calculations or estimations.

Figure 1
Respiratory Severity Score (RSS) profiles plotting the median weekly averages for each gestational age over post-menstrual age (PMA).

Figure 2
Respiratory Severity Score (RSS) profiles plotting the median weekly averages for each gestational age over post-menstrual age (PMA), with 95% CIs for the median values.