Frequency of Acid-Base Derangements Among the Neonates Admitted to the Intensive Care Unit

Abstract

Background: Every year deranged acid-base physiology drives admission to a critical care arena for a vast number of neonates. The neonatal intensive care unit is a fundamental sector for the survival of high-risk newborns. The acid-base disorder must always be considered in the clinical setting. The clinician should, in most cases, be able to predict the type of acid-base imbalance before the blood gas is available. Arterial blood gases (ABG-s) are the gold standard for assessing the adequacy of oxygen delivery, ventilation, and pH. This study aimed to assess the frequency of acid-base derangements among neonates admitted to the intensive care unit. Material & Methods: This was an observational cohort study that was conducted in the Neonatal Intensive Care Unit (I.C.U.) of Dhaka Shishu Hospital, Dhaka, Bangladesh during the period from October 2009 to September 2010. In total 230 neonates admitted to the Neonatal Intensive Care Unit, after fulfilling the inclusion criteria were enrolled in this study as study subjects. For each baby, a detailed history was recorded in a questionnaire form (enclosed herewith) from the mother or other caregiver. It was filled up by the researcher himself containing history (including antenatal history), physical examinations and laboratory findings. Arterial blood gas analysis was done (in a clinical biochemistry laboratory using an automatic analyzer machine) for each neonate at admission and that report was recorded for this study. Results: Among the total study subjects, 127 newborn babies (55.2%) had acid-base imbalances. Mixed acidosis prevailed in the highest frequency (23.9%) Then metabolic acidosis cases were at 17.8% and respiratory acidosis was at 13.9%. Metabolic alkalosis and respiratory alkalosis were absent. Normal blood gas was observed in 44.3% of newborns. All the neonates with pH <7 were dead. After Chi-Square analysis (at df=1), we found a highly significant correlation between mortality outcome with pH <7.35, CO2 >45, HCO3 < 22 mol/l and Base deficit >-10. All modalities of acid-base imbalances were significantly associated with mortality. Conclusion: In this study, a significant number of neonates who were admitted to the intensive care unit, can develop acid-base derangement. Mixed acidosis was found in the highest frequency. Metabolic, respiratory and mixed acidosis all has a significant correlation with death in a NICU. Metabolic alkalosis and respiratory alkalosis were found absent at admission.