Dr NGAI Chun Wai; Supervisor: Dr WM CHAN; Adult Intensive Care Unit, Queen Mary Hospital
Background: Acute Kidney Injury is a common complication of septic shock and it carries high mortality and morbidity. However, there is no good marker to predict its occurrence. NGAL is a novel renal biomarker showing promising result in the prediction of acute kidney injury in patients across different clinical settings. Another potential marker is Doppler based resistive index of renal interlobar artery, which has been shown to be useful in identifying those patients with septic shock who will develop acute kidney injury.
Objective: To evaluate the predictive value of RI and NGAL in the early detection of acute kidney injury in patients with septic shock.
Design: A prospective, observational study in a 20-bed medical / surgical intensive care unit of a university teaching hospital.
Patients: All patients presented with septic shock during the study period, excluding those with chronic renal failure (serum creatinine >120μmol/l)
Measurement: Within the first 24 hours after the introduction of vasopressor, resistive index was determined by two independent operators by Doppler ultrasonography, and the plasma and urine were collected for NGAL measurement. The presence of acute kidney injury was evaluated at Day 3, according to the RIFLE criteria. RI and NGAL were compared between patients with “Acute kidney injury” (RIFLE class-I/F) and “No acute kidney injury” (no RIFLE class and RIFLE class-R).
Results: During the period from August 2010 to January 2011, 30 patients with septic shock were recruited. 18 patients were classified as the group of “Acute kidney injury” and the other 12 patients as the group of “No acute kidney injury”. More patients in the group of “Acute kidney injury” had pre-existing diabetes mellitus. No other significant difference was found between the two groups including baseline serum creatinine. Patients with acute kidney injury had significantly higher RI (mean = 0.73 vs. 0.58, p<0.001) at enrollment compared with patients with no acute kidney injury. Concerning NGAL, patients with acute kidney injury had significantly higher plasma (median = 177.87 vs. 88.53ng/ml, p=0.001) and urine (median = 169.7 vs. 52.5ng/ml, p<0.001)) NGAL at enrollment compared with patients with no acute kidney injury. Receiver operating characteristic curve (ROC curve) for RI, plasma and urine NGAL as a predictor of acute kidney injury on Day 3 had an area under curve of 0.866, 0.87 and 0.898 respectively.
Conclusion: Resistive index, plasma NGAL and urine NGAL all appear to be good predictors of acute kidney injury in patients with septic shock.