Editing Pathophysiology of Urinary Tract Obstruction (section)

==== Management ====
* '''<span style="color:#ff0000">Continuous urinary drainage</span>'''
**'''Intermittent or gradual drainage is no longer recommended'''
*** Intermittent or gradual drainage of an obstructed bladder was thought to potentially decrease the rates of hematuria and hypotension. However, with quick drainage the rates of hematuria are generally low and not severe, while the decrease in blood pressure represents a normalization of the pressure without cardiovascular compromise.
* '''<span style="color:#ff0000">In patients with normal mental status, no evidence of fluid overload, normal electrolytes, and normal renal function</span>'''
** '''<span style="color:#ff0000">Regular monitoring of (3):</span>'''
**#'''<span style="color:#ff0000">Orthostatic vital signs</span>'''
**#'''<span style="color:#ff0000">Electrolytes</span>'''
**#'''<span style="color:#ff0000">Urine output</span>'''
** '''<span style="color:#ff0000">Free access to oral fluids</span>'''
*** '''Generally, patients with a normal mental status should not be given IV fluids because this may prolong the period of diuresis'''
* '''<span style="color:#ff0000">In patients with evidence of a pathological post-obstructive diuresis</span>'''
** '''<span style="color:#ff0000">More frequent monitoring of vital signs, urine output, electrolytes (every 12 hours or more often if necessary), and urine osmolality</span>'''
*** '''Patient can become hypovolemic as a result of excess water loss, and electrolyte abnormalities may develop as result of salt or potassium wasting'''
**'''<span style="color:#ff0000">Patients should continue to have free access to oral fluids.</span>'''
* '''<span style="color:#ff0000">Patients with poor cognitive function [or signs of dehydration] should be given IV fluids, although at a rate below maintenance.</span>'''
** '''<span style="color:#ff0000">The type of fluid used depends on the volume and sodium status</span>''' (from AUA update)''':'''
*** '''<span style="color:#ff0000">Normal volume status</span>''' (normal blood pressure):
**** '''<span style="color:#ff0000">Fluid replacement with free water (oral or IV) should be considered if there is a water diuresis</span> (suggested by hypernatremia and a low urine osmolality).'''
***** Caution should always be taken to avoid correcting sodium alterations too rapidly.
*** '''<span style="color:#ff0000">Hypovolemia (low blood pressure)</span>'''
**** '''<span style="color:#ff0000">0.9% saline is usually the fluid of choice</span>'''
**** '''If the volume deficit is not severe, 0.45% saline can also be used (particularly if hypernatremia is present)''' to provide sodium and water to help the kidneys maintain homeostasis.
*** Sometimes it is recommended that urine output be replaced with 0.5 ml fluid per 1 ml urine. While this may help prevent hypovolemia, it can also propagate the diuresis if the fluid replacement is inappropriately high for the patient.
*** '''Hypokalemia can occur and lead to life threatening arrhythmias if severe.''' As a result, potassium should be replaced aggressively, particularly if renal function is improving. Other electrolyte abnormalities should be corrected as well.
** '''The urine is usually isosthenuric initially, and IV fluid replacement with 0.45% saline administration at a rate lower (50-75%) than the hourly urine output is recommended; 0.9% normal saline and Lactated Ringer have no role in post-obstructive diuresis and should not be given''' '''[SASP contradicts AUA Update]'''