Risk Factors For Postoperative Acute Kidney Injury (AKI) Following Laparotomy For Abdominal Emergencies At The Korle- Bu Teaching Hospital

Abstract

Background: Postoperative acute kidney injury (AKI) is associated with increased morbidity, cost, prolonged hospital stay, and greater than 50% mortality rate in abdominal surgery. Among abdominal procedures, open surgical technique has the highest risk of postoperative AKI as compared to the laparoscopic approach. Postoperative AKI is a common condition in laparotomy patients. In patients with emergency abdominal conditions, laparotomy offers the only chance for cure. Various complications (such as pneumonia, wound infection, deep vein thrombosis, and impaired renal function) occur in these patients. However, the risk factors for postoperative acute kidney injury (AKI) and its effects on the clinical outcomes at the Korle-Bu Teaching Hospital are not well understood. There is therefore the need to collate data General Aim: To determine the incidence and risk factors of postoperative AKI following laparotomy for abdominal emergencies in patients with previously normal renal function at the Korle-Bu Teaching Hospital. Methodology: This was a prospective cohort study that was carried out on 200 patients undergoing emergency (100 patients) and elective (100 patients) laparotomy following abdominal emergencies at the surgical department of Korle Bu Teaching Hospital from June 2015 to June 2016 with a mean age of (41± 17.41) years. Five (5) mls of venous blood sample was drawn from each patient pre and post operation. Serum urea, nitrogen and creatinine were determined by modified Jaffe reaction method using Pentra C200 auto analyzer. Serum Potassium, Chloride and Sodium levels were determined using a flow technique by an Idexx VetLyte electrolyte auto analyzer. Full blood count was determined by an automated Mindary BC-6800 haematology analyzer. The 24 hours post-operative urine output was measured using a calibrated urine cup. Blood pressure was measured using an osillometric Omron device validated in adults while a digital thermometer was used in measuring body temperature. An Omron digital scale was also used to measure patient weight. Using the ratio of blood urea nitrogen (BUN, mg/dl) over serum creatinine level (Cr, mg/dl) as a marker of relative renal function and KDIGO classification which define postoperative AKI as an increase in absolute serum creatinine of at least 0.3 mg/dL or by a percentual increase in serum creatinine equal to or higher than 50% (1.5X baseline value) and/or by a decrease in urine output lower than 0.5 mL/kg/hour for more than 6 hours. Results: The mean age of the 200 patients who underwent laparotomy was 41±17.41 years; the majority of the patients were males 133 (66.5 %) while 67 (33.5%) were females. The incidence of postoperative AKI following laparotomy is approximately is 4.5%. Multivariate analysis using logistic regression was performed to quantify the association of BUN/Cr ratio with AKI. The development of postoperative AKI was significantly associated with advanced age (p=0.01), emergency laparotomy (p=0.02), pre-operative anaemia (p=0.01) an adjusted R-Square of 0.286 shows that comorbidity and postoperative BUN/Cr jointly determine 28.6% of the variance risk for AKI. Conclusion: The incidence of postoperative AKI following laparotomy is high in korle-Bu Teaching Hospital. Old age, emergency laparotomy surgery, male gender, pre-operative anaemia and co-morbidity such as diabetes and hypertension are predictive factors associated with postoperative AKI. Appreciation of these factors may help to identify high-risk laparotomy surgical populations to reduce the risk of postoperative AKI and to achieve optimal treatment in the event of occurrence of postoperative AKI.