Figure 1.

Schematic description of the study of the influence of volatile anesthesia on urine output and handling of sodium in pediatric elective outpatient hypospadias surgery. After initiation of sevoflurane anesthesia the urine bladder was emptied with a remaining Koyle stent. A venous blood sample was collected half-way into surgery (anticipated) and later analyzed for Na⁺, K⁺, creatinine, renin, and arginine–vasopressin (AVP). Throughout the anesthesia-period urine was collected for determination of urine output and analyses of Na⁺, K ⁺, and creatinine. After surgery the anesthesia was discontinued and the children were awakened in the operating room. They were then transferred to the recovery unit where they stayed for at least 2 h before they were again transferred to the pediatric ward. At the pediatric ward urine was collected for 2 h and venous blood was sampled 1 h after urine sampling was commenced.