Avaliação da disnatremia em pacientes com indicação de suporte renal em unidades de terapia intensiva

Abstract

Dysnatremias are the most common electrolyte disorder reported in about 30-40 % of hospitalized patients. When present at Intensive Care Unit (ICU) admission are independent risk factors of poor prognosis and associated with an increased hospital mortality. Even borderline dysnatremias (130-135 mEq/L in hyponatremia and 145-150 mEq/L in hypernatremia) has been associated with increased hospital mortality and a longer ICU stay, regardless of the severity of the underlying disease.Serum sodium concentration is maintained by a precise renal control of salt and water. Patients with dialytic and non-dialytic chronic kidney disease (CKD) have a higher prevalence of dysnatremia comparing with the non-CKD population. Hyponatremia is more frequently observed, although both hypo- and hypernatremia have been associated with an increased mortality in this population. To the best of our knowledge, there is no clear report of dysnatremia prevalence in acute kidney injury (AKI), specially in severe AKI in-need of renal replacement therapy (RRT), neither consistent information on its impact on outcomes in this population. The present study aimed to evaluate the prevalence of dysnatremia and its impact on the prognosis of critically ill patients with Acute Kidney Injury (AKI ) in-need of RRT in the ICU. From December 2004 to July 2008 all patients who started on renal support at 14 ICUs in 3 tertiary hospitals in Rio de Janeiro were prospectively included. Clinical and laboratory data were entered into a spreadsheet and analyzed later with the software R. The dependent variables were ICU and hospital mortality. Variables that, additional to serum sodium concentration, presented association with outcomes in the bivariate analysis were selected the included in the multiple logistic regression model . A total of 772 patients were included in the study. The median age was 75 [IQI; 61-82 yo]; 81.5% (CI: 78.4-84%) were clinical ICU admissions. Eighty four percent of patients had at least one comorbidity (hypertension, diabetes, coronary disease, heart insufficiency, chronic pulmonary disease or cirrhosis) and 72.5% (CI: 69.2-75.7%) had sepsis. The main factors contributing to AKI were sepsis (72 %) and ischaemia/shock (66 %). ICU and hospital mortality were respectively 64.6 % (CI: 61.1 %-68 %) and 69.7 % (CI: 66.3 % -72.9 %). Dysnatremia was frequently observed being present in 47.3 % (CI: 43.7 %-50.9 %) of the study population. In multivariate analysis, older age, clinical admission, number of comorbidities, and the number of organ dysfunctions were associated with an increased hospital mortality. Patient with severe hypernatremia (serum sodium above 155 mEq/L) showed a higher association with ICU and hospital mortality (adjusted odds ratio 3:39 (CI 1.48 to 7.8 ) and 2.87 (CI 1.2 to 6.89), respectively), despite all patients had underwent RRT.The present study demonstrated that dysnatremia are highly prevalent in AKI in-need of RRT in the ICU. Hypernatremia is the main sodium disturbance contrasting with the reported in CKD and ICU populations. Older age, clinical admission, number of comorbidities and severe hypernatremia are associated with a worse ICU and hospital outcome in AKI patients in-need of RRT in the ICU.