Initial Paco2 Values at One Hour in Very Low-Birthweight Infants(VLBW)< 1000g and Oxygen Requirement at 28 days: Are Delivery Room Events Important? † 1122

Abstract

Recent observational studies suggest a relationship between low Paco2 values in the mechanically ventilated VLBW infants and neonatal morbidity, i.e., chronic lung disease. Permissive hypercapnia has been advocated as one approach to minimize such lung injury. However, the time of initiating such a strategy and factor (s) that influence postnatal Paco2 values are not well characterized. The study objective was to determine the effect of delivery room resuscitation on early Paco2 levels and the relation to O2 requirement at 28 days in VLBW infants 40 (n=42, 43%) (m=46.8±6.3mmHg), ≥45(n=23, 24%) (m=50.6±6.4mmHg). 19 patients (20%) had Paco2 0.05) respectively. The lowest Paco2 values were following abruption(m=23±7mmHg) and multiple gestation (m=32±12mmHg). Of infants with Paco2<35mmHg at one hour, 25/33 (76%) vs 10/23 (44%) of infants with Paco2≥45 group required O2 at 28 days(p<0.03). At 3 hours of age 16/19 (84%) infants with Paco2<35mmHg vs 14/27 (52%) with Paco2≥45mmHg required O2 at 28 days(p<0.01). These data indicate that approximately one-third of VLBW have low Paco2 values upon NICU admission. Infants with a low Paco2 within the first hour of life are more likely to require O2 at 28 days compared to infants with relatively higher initial Paco2 values. Delivery room resuscitative events likely contribute to the low Paco2, although the specific mechanism (s) are not clear from this observational study. Any strategy designed to promote permissive hypercapnia should include optimizing delivery room resuscitation.