[Two-hour evaluation of renal function in the elderly]

Elderly have progressive renal function deterioration and hypertensive patients are at higher risk of additional intraoperative kidney injury. Renal function is evaluated by creatinine clearance, with 24-hour urinary output to dilute the error of possible residual vesical volume (RVV). This study aimed at evaluating preoperative renal function of hypertensive and normotensive elderly patients, with 2-hour urinary output, using portable ultrasound to determine residual vesical volume.

Participated in this study 30 patients distributed in 2 groups: Gn (15) normotensive elderly, and Gh (15) hypertensive elderly. Urine was collected for 2 hours. RVV was measured with portable ultrasound. The following parameters were evaluated: age, gender, physical status, height, weight, body mass index, plasma and urinary creatinine, plasma and urinary sodium and potassium, plasma and urinary osmolality, urinary output, creatinine, osmolar and free water clearance, sodium and potassium urinary and fractional excretion. Estimated creatinine clearance was compared to actual creatinine clearance.

Gn and Gh patients were not significantly different in most evaluated parameters. Hypertensive elderly had a trend to higher sodium fractional excretion and plasma potassium was lower in hypertensive patients, however within normal ranges. Estimated creatinine clearance was positively correlated to actual creatinine clearance in Gn only.

Hypertensive patients had lower plasma potassium and excreted more sodium, with correspondence between estimated and actual creatinine clearance in normotensive patients only.