ABSTRACT
Glomerular filtration rate (GFR) is an accepted measure for assessment of kidney function. For the critically ill patient, creatinine clearance is the method of reference for the estimation of the GFR, although this is often not measured but estimated by equations (i.e., Cockroft-Gault or MDRD) not well suited for the critically ill patient. Functional evaluation of the kidney rests in serum creatinine (Crs) that is subjected to multiple external factors, especially relevant overhydration and loss of muscle mass. The laboratory method used introduces variations in Crs, an important fact considering that small increases in Crs have serious repercussion on the prognosis of patients. Efforts directed to stratify the risk of acute kidney injury (AKI) have crystallized in the RIFLE or AKIN systems, based in sequential changes in Crs or urine flow. These systems have provided a common definition of AKI and, due to their sensitivity, have meant a considerable advantage for the clinical practice but, on the other side, have introduced an uncertainty in clinical research because of potentially overestimating AKI incidence. Another significant drawback is the unavoidable period of time needed before a patient is classified, and this is perhaps the problem to be overcome in the near future.
ABSTRACT
PURPOSE: This study aimed to measure the point prevalence of kidney dysfunction (KD) in the intensive care setting. MATERIALS AND METHODS: A point-prevalence, single-day, prospective study was conducted. Of 919 patients present in 42 Intensive care units (ICUs) for 2 specific days (September 2009 and March 2010), 832 cases were included. Mild KD was defined as a measured creatinine clearance of 90 to 60 mL min(-1) 1.73 m(-2), and severe KD was defined as a creatinine clearance less than 60 mL min(-1) 1.73 m(-2). RESULTS: Prevalence of mild KD was 15.9/100 patients/d (13.5-18.5), and severe KD was 42.4/100 patients/d (39.1-45.8). We considered as having a low probability of experiencing KD those patients without chronic kidney disease, acute kidney injury network stage 0, and a serum creatinine less than 1.2 mg/dL, but among them (557 patients), 18.1% (15.2%-21.6%) had mild KD and 24.2% (20.9%-28%) had severe KD. ICU mortality was 10.6% (7.81%-14.4%) for patients without dysfunction, 16.6% (11.2%-24%) for patients with mild KD, and 29.7% (25.2%-34.7%; P<.001) for patients with severe KD, with a relative risk for severe KD vs no KD of 2.54 (1.90-3.40). In 54.3% patients, at least 1 renal insult was reported. One nephrotoxic drug was administered to 34.4% and 2 or more to 14.9% patients, with a lower frequency among those with chronic kidney disease (30.6% vs 50.8%; P<.05). CONCLUSIONS: Each day of study, more that half of the patients admitted to the ICU showed some derangement in kidney function. More than 25% of patients not fulfilling the KD criteria by serum creatinine or acute kidney injury network showed, in fact, a severe KD, and this finding was associated with higher mortality. More than 50% of the patients admitted to the ICU were subjected to at least 1 renal insult.
