Acid Base Disorders in Critically Ill Neonatal Intensive Care Patients and Predicting Survival by the Presence of Deranged Acid-Base Variables

Objective: The acid base abnormalities are common in neonates with birth asphyxia and sepsis leading to considerable morbidity and mortality and timely assessment and management of these acid-base derangements leads to a better outcome. So, we did a observational study to assess acid base disorders in neonates by using Boston, Copenhagen approach and Stewart approach and the role of the various variables on predicting the acid base status and the worst outcome in neonates. Study design and methods: An observational study was conducted on the samples provided from the neonates with birth asphyxia and sepsis admitted to neonatal intensive care unit (NICU) in the Post Graduate Institute of Medical Education and Research (PGIMER) and Dr Ram Manohar Lohia (Dr RML) Hospital, New Delhi, India. The blood gas analysis, electrolytes, albumin, lactate levels were compared in the two ailments. The presence of acid base disorders were calculated using Copenhagen approach and Stewart method; and the influence of various variables on acid base disorders and outcome were analyzed. Results: The metabolic acidosis and alkalosis were seen in 1 and 10 patients as per Boston approach and in 18 and 18 patients with Copenhagen approach. The increased anion gap (AG), and low and high strong ion difference (SID) as measured by Stewart approach were seen in 23,21 and 23 neonates respectively. The acid-base status determined by both Copenhagen and Stewart approach were found to be interrelated. For detecting metabolic acidosis the sensitivity of high for high anion gap (66.67%) and hyponatremia (57.89 %) , whereas the specificity is high for lactic acidosis (94.74 %), hyperchloraemia (86.99%) and hyponatremia (81.08%). The low PaCO2 (89.4%) and low SID (73.68%) has a high sensitivity for predicting the non-survival , whereas the lactic acidosis(94.74%) has the high specificity of predicting the non-survival , followed by hyponatremia (81.08%), low SID (75.68%), hypoalbuminaemia (70.27%) and low PaCO2 (70.27%). Conclusion: In neonates with birth asphyxia and sepsis, acid-base disorders are common. Both the approaches are good in determining the acid-base status, but in complicated situation strong ion difference and strong ion gap works better in determining acid-base status. Derangements like low PaCO2, low SID, hypoalbuminaemia, lactic acidosis and hyponatremia are predictors of worst outcome.