The Incidence and Outcome of Acute Renal Failure in the Surgical Intensive Care Unit

INTRODUCTION: Acute renal failure (ARF) in critically ill patients is associated with a high mortality rate. Several pathophysiologic mechanisms associated with ARF have enhanced our understanding of the disease. ARF can result from alterations in renal perfusion, changes in glomerular filtration and tubular dysfunction. Early intervention and correction of these factors can alter the effects of ARF. Several new potential interventions including renal replacement therapy (RRT) have been developed that can change the course of ARF in the critically ill. Despite improvements in intensive care and dialytic technology, there have not been significant improvements in patient survival over the past few decades. There is no consensus definition of ARF in critically ill patients. Many different definitions have been used in the literature, making comparisons difficult. Timely identification of the severity of ARF using relevant criteria and aggressive intervention remains the key to higher success rates in dealing with these patients. In our study we aim to assess the ability to identify the severity of ARF in the surgical intensive care unit using a new criteria called the RIFLE score (Risk, Injury, Failure, Loss and End stage renal disease), and the effects of early identification of the vulnerable population on the outcome. AIMS AND OBJECTIVES: 1. To determine the incidence of Acute Renal Failure in a cohort of patients with risk, injury and failure factors admitted to the Surgical Intensive Care Unit of the Christian Medical College Hospital. 2. To assess the mortality in patients who developed acute renal failure. MATERIALS AND METHODS: The design of the study was a unicenter observational prospective cohort study. There was no intervention. The duration of the study was a fixed six month period from February 2006 to July 2006 (6 months). Study Population: This study was conducted on all patients >14 years admitted to the surgical intensive care unit, fulfilling any one of the inclusion criteria for acute renal failure. The inclusion criteria that was used for this study is the RIFLE criteria for classifying Renal failure. Patients were excluded from the study if a) Age was less than 14 years. b) Loss or End stage renal disease as defined by RIFLE. Sample Size: As per the statisticians advice a defined period of study was chosen before the onset of study. This period was chosen as six months. All patients admitted under the surgical intensive care unit of this tertiary referral hospital would be screened with the RIFLE criteria and subsequently be included in the study. RESULTS: Incidence of ARF: During the six month study period 422 patients were admitted to the surgical intensive care unit. Of these patients 97 met the RIFLE criteria for acute renal failure. The calculated incidence of ARF is 22.7%. Demographic pattern of ARF : Of the 97 patients diagnosed to have ARF, the distribution of patients across the deciles of age was a normal distribution, with a bulk of the patients falling in the 30 to 69 age group (Table–1). With respect to sex of the patient (Table-2), males had higher incidence 73.2% vs. 26.8%. Classification of ARF: In this study, 47% of the patients with ARF belonged to the risk category, 31% of the patients belonged to the injury category and 22 % belonged to the failure category. (Table-3). Etiology of ARF: The leading cause of ARF in the study cohort was sepsis. 55 of the 97 patients were diagnosed with sepsis. The next most common cause of ARF was polytrauma(10%). ARF following post arrest sequelae was the etiology in 10% of the patients. Hepato renal syndrome and hemorrhagic shock caused ARF in 6 and 4 % of the patients respectively.( Table 4). Mortality in patients with ARF: Of the 97 patients admitted with ARF the mortality rate was 47%(n=46). The leading cause of mortality was sepsis (Table 4). The case fatality rate for sepsis was 62%. The combination of sepsis with ARF is associated with a high mortality in our study. Sepsis was found to be a significant cause of mortality (p<0.01). Polytrauma was found to be a significant cause of mortality (p