Perioperative urinary output and course of diuresis during outpatient treatment under general anesthesia.

Hypotension due to vasodilatation or hypovolemia is a common complication
during general anesthesie. This is treated by infusion of fluids or
vasopressive medication.

Urinary retention is a known postoperative complication after spinal anesthesia
but is also seen after general anesthesia. Risk factors for this complication
are for example age, duration of surgery or the given amount of fluid.

Unexpected bladder distention is sometimes found in patients who did not seem
to be at risk for urinary retention given the duration of surgery or the given
amount of fluid. The effect of general anesthesia and the infusion of different
kinds of fluid on urinary output and course of diuresis is unknown

In this study we would like to investigate whether there is a correlation in
fluidmanagement and hemodynamics under general anesthesia and total
perioperative urinary output, to eventually prevent bladderdistention.

Main question:
Does a restrictive fluid management during general anesthesia lead to less
urinary production?

Sub questions:
Does a fluid management with colloid fluid during general anesthesia lead to a
change in urinary production?
Does a different kind of fluidmanagement lead to a difference in hemodynamics
during general anesthesia?

prospective, randomised single-blind study

questionary preoperative screening
questionary preoperative
bladderscan preoperative
questionary thirst/bladderdistention/urge every half hour postoperative
(minimum of 4 times)
bladderscan every half hour (minimum of 4 times)
collection of urine in case of spontaneuous urination

risks:
the standard risks of general anesthesia like hypotension, hypovolemia.