Abstract
Early studies suggest an association of abnormal carbon dioxide (PCO2) or oxygen (PO2) levels with adverse inpatient outcomes in very preterm babies. Recent resuscitation practice changes, such as targeted oxygen therapy, end-expiratory pressure, and rescue surfactant may influence these associations. The aim of this study is to assess the range of the initial partial pressures of PCO2 and PO2 in preterm neonates <33 weeks gestational age after birth and their correlation to inpatient neonatal outcomes. This is a prospective observational cohort study of infants <33 weeks gestational age with arterial or venous blood gas analysis performed within the first hour after birth. One hundred seventy infants (arterial n = 75, venous n = 95) with mean (SD) gestational age of 28 (3) weeks and birth weight of 1,111 (403) g were included. None of the infants with arterial blood gases had hypocarbia (<30 mmHg), 32 (43%) had normocarbia (30-55 mmHg), and 43 (57%) had hypercarbia (>55 mmHg). Seventeen of the infants with arterial blood gases (22%) had hypoxia (<50 mmHg), 50 (67%) normoxia, and 8 (11%) hyperoxia (>80 mmHg). In infants with venous blood samples, none had venous PCO2 < 40 mmHg, 41 (43%) had venous PCO2 40-60 mmHg, and 54 (57%) had venous PCO2 > 60 mmHg. Multivariable logistic regression analysis showed no association of low or high PCO2 or PO2 with death or major inpatient morbidities. With current resuscitation and stabilization practices, hyperoxia and hypocarbia was uncommon, and hypercarbia occurred frequently. None of these findings correlate with adverse inpatient outcomes or death. Our findings are in direct contrast to published observations using historical practices.
Highlights
High and low levels of carbon dioxide and oxygen in the first few hours or days after birth have been associated with inpatient mortality and morbidities in very preterm babies [1,2,3]
There was a greater number of arterial blood gases collected from preterm infants who were
Measurement and confirmation of hypoxia, hyperoxia, hypocarbia, and hypercarbia after very preterm birth is an inexact science, and prevalence may vary based on clinical practices
Summary
High and low levels of carbon dioxide and oxygen in the first few hours or days after birth have been associated with inpatient mortality and morbidities in very preterm babies [1,2,3]. Respiratory support in the DR often included (i) self-inflating bags, (ii) no positive end-expiratory pressure (PEEP), (iii) early intubation, and (iv) prophylactic surfactant administration [5, 6]. Invasive respiratory support can cause lung injury in preterm infants through several mechanisms including high pressures (barotrauma), hyperinflation and overdistension (volutrauma), alveolar instability due to repeated expansion and collapse (atelectrauma), and the release of inflammatory mediators (biotrauma) [7]. Studies suggest an association of abnormal carbon dioxide (PCO2) or oxygen (PO2) levels with adverse inpatient outcomes in very preterm babies. Recent resuscitation practice changes, such as targeted oxygen therapy, end-expiratory pressure, and rescue surfactant may influence these associations
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