Birthweight, early passive respiratory system mechanics, and ventilator requirements as predictors of outcome in premature infants with respiratory failure

Abstract

Early respiratory mechanics have been reported to predict outcome in newborns with respiratory failure. However, it remains unknown whether measurements of pulmonary function add significantly to the predictive value of more readily available variables The present study was designed to answer this question. Passive respiratory system mechanics were measured by an airway occlusion technique in 104 ventilator-dependent premature infants between 6 and 48 hours of life and corrected for infant size. A ventilation index [FiO2 x mean airway pressure (MAP)] was calculated at the time of pulmonary function testing. Poor outcome was defined as death from respiratory failure or need for supplemental oxygen at 28 days. Stepwise logistic function regression examined whether ventilation index and respiratory mechanics added predictive power over and above birthweight. Five infants died, and 45 patients required supplemental oxygen at 28 days. Birthweight was a strong predictor and would have entered the logistic model first in any case. Ventilation index added significantly to the predictive model (P = 0.038). Respiratory system conductance (P = 0.15) and compliance (P = 0.93) entered on the third and last step, respectively. We conclude that in premature infants with respiratory failure, birthweight is a strong predictor of outcome. Early ventilator requirements but not respiratory system mechanics, add significantly to this predictive model.

Respiratory mechanics in ventilated preterm infants: early determinants and outcome

“…19,46,70,89,137,160,256 Increased respiratory system resistance may both contribute to development of lung damage and be a manifestation of CLD itself. Airway damage secondary to endotracheal intubation, positive pressure, and/or high oxygen concentrations may cause increased respiratory system resistance, as may increased pulmonary blood flow or left heart failure secondary to a patent ductus arteriosus (PDA) causing peribronchial oedema.…”

“…Therefore, the number of a priori selected predictors was limited, increasing the risk of missing valuable predictors, for example, ventilator conditions, which have been studied as potential predictors of respiratory course before. 91,137,214,256,270 Since in small data sets regression coefficients tend to overestimate, we used the heuristic shrinkage method to correct for this effect. However, external prospective validation in a comparable group of infants is still recommended before widespread use of the prediction models can be encouraged.…”

“…Previous studies mainly described prediction models for CLD development 91 at 28 days 19,62,89,160,210,215,256,270 or 36 weeks 87,95,160,214 and only a few were able to be applied within 2 days after birth. 70,137,154 However, since the latter studies were performed before the surfactant era, results were not attributable to current practice. Furthermore, instead of predicting CLD development, prediction of different aspects of neonatal respiratory course may create new possibilities as to specific preventive measures in clinical practice as well as future research, for example, early selection of infants at high risk of postnatal corticosteroid therapy in order to study the effects of early administration of postnatal corticosteroid therapy.…”

“…Results relating these parameters to respiratory outcome are conflicting, particularly with regard to the development of CLD. 19,70,89,91,137,160,219,256 Moreover, most of these studies were performed before the use of prenatal corticosteroids and the introduction of exogenous surfactant therapy. As a consequence of these recent developments in perinatal care, the survival of more immature infants has increased.…”

“…In the past, neonatal and childhood respiratory function have been studied extensively in relation to preterm birth 78,94,179,193,243 , CLD development 15,19,70,85,89,91,137,160,193,219,256 , and neonatal therapeutic interventions. 94,151,196,275 Only one of these studies consequently performed serial respiratory function measurements in 24 infants, who developed CLD, during the first 2 years of life commencing in the neonatal period.…”