Acute Renal Failure in Neonates with Perinatal Asphyxia and its Correlation with HIE Staging: A Prospective Case Control Study

Introduction: Perinatal asphyxia, the prime cause for neonatal mortality and morbidity, results in hypoxic damage to almost all organs of the neonate, kidneys being most frequently (50%) affected. However, neonatal renal failure poses diagnostic as well as therapeutic challenge as clinical and laboratory parameters are unpredictable in this age group. Paucity of studies determining the incidence and outcomes of renal failure in neonates with perinatal asphyxia has impelled the present study. Objectives: To determine the incidence of acute renal failure and its predisposing risk factors in term neonates with perinatal asphyxia and to correlate its severity with hypoxic ischemic encephalopathy (HIE) staging. Materials and methods: This Prospective case control study was conducted in a tertiary level neonatal intensive care unit, in Deccan college of Medical Sciences, Hyderabad, Telangana, India. Inclusion and exclusion criteria: Consecutive term neonates admitted to NICU with perinatal asphyxia were enrolled as cases and 50 term neonates without it were selected as controls, after obtaining written informed consent. Neonates with major congenital anomalies were excluded. Methods: Relevant perinatal history and examination findings along with biochemical results were recorded in a predesigned, pretested performa and the asphyxiated neonates were managed as per the standard guidelines. Results: There were total 75 cases with perinatal asphyxia and 50 non asphyxiated controls (1.5:1 ratio). Over all incidence of perinatal asphyxia was 7%. Baseline variables were similar among cases and controls. Extramural neonates had significantly higher incidence of perinatal asphyxia (P=0.001). Overall, 60% of asphyxiated neonates had HIE stage II and 17.3% had stage III. Acute renal failure was evident in 70.7% of cases and 2% of controls, with statistical significance. Commonest risk factors for perinatal asphyxia were MSAF (40%) and positive sepsis screen (64%). While, 64% (48/75) of cases had screen positive sepsis, it was seen only in 18% (9/50) of controls, with statistical significance (P value: 0.001). 40% (30/75) of the cases had shock and 18.7% (14/75) of cases required ventilator support. Thus, shock and respiratory failure were significantly more common in asphyxiated neonates than those without asphyxia. Incidence of renal failure amongst the cases with perinatal asphyxia was 70.67% (53/75) and 2% (1/50) in controls, with statistical significance(X 2 -57.65, p value of 0.001) and 90.5% (48/53) of cases had pre renal azotemia, and non oliguric renal failure was seen in 73.5% of cases. Thus, the predominant type of renal failure among the cases was pre renal, non oliguric and intrinsic renal failure was evident in 9.4% of cases. 86.7% of Neonates with HIE II and100% of those with stage III had acute renal failure. Neonates with HIE stage II and III were more prone for shock and respiratory failure (multi organ dysfunction) and in turn had higher incidence of renal failure. Conclusions: Incidence of renal failure was significantly high among the cases than controls and neonates with severe perinatal asphyxia had more frequent acute kidney injury. The predominant type of renal involvement was pre renal and non oliguric. Neonates with HIE stage II & III had significantly higher incidence of acute renal failure. Screen positive sepsis, shock and respiratory failure were major correlates of renal failure in asphyxiated neonates.