Effect of serum urea and creatinine levels in aneurysmal subarachnoid hemorrhage

Background: Acute kidney injury is a major problem in all critically ill patients and has a poor effect on the outcome. We have determined the burden of acute kidney injury in aneurysmal subarachnoid hemorrhage (aSAH) patients. Aims and Objectives: We have studied the levels of serum urea and creatinine in aSAH patients and have investigated its effect on the outcome of such patients. Methodology: A retrospective review of the levels of serum urea and creatinine in 1000 cases of aneurysmal subarachnoid hemorrhage was done from the records of Thomas Jefferson University Hospital, after obtaining the requisite permission from the Institution Review Board. The level of serum urea, creatinine and their ratio was documented. Parameters were initially analyzed by student's t test, p <0.05 is taken as significant and were further scrutinized by multivariate regression analysis. Results: Increased values of serum urea (BUN), creatinine as well as their ratio are associated with poor outcome (p <0.05), although BUN: creatinine ratio < 9 was also related to bad outcome. While comparing the variables, BUN: creatinine ratio seems to have the greatest and creatinine the least, impact on patient prognosis. BUN: creatinine ratio > 22.2: 1 (95% confidence interval, 21.2: 1- 23.5: 1) accounted for more chances of a poor outcome. Weaknesses of the study: BUN and creatinine levels do not rise above the normal range until 60% of total kidney function is lost and hence by considering them alone we miss out on patients with less severe renal damage. Long term follow up of the patients were not analyzed. Conclusions: Electrolytic imbalances affecting the short term prognosis of aSAH patients are mainly following the cardiovascular or neurologic damage and are least likely as a result of direct kidney injury.