Oliguria in a post-op patient

Source: Dr Michael Tam at http://vitualis.wordpress.com/2006/05/14/iv-fluid-therapy-in-post-operative-oliguria/

Common problem seen on overtime.

Step 1: Ensure that it is true oliguria.
- Check: IDC isn’t blocked, no post-operative urinary obstruction/retention (physical examination of the abdomen and a ward bladder scan optimally). [post-renal causes]

Step 2: Does the patient have pre-existing renal failure? This could explain the oliguria (look up the pre-op UECs).
- <30 mL/h = acute renal failure
- Ideal: >1 mL/kg/hr.

Step 3: Is the patient dehydrated? [pre-renal causes]
- Rehydrate with NS: 500ml bolus, then 500ml/hr
- Reassess & repeat if necessary

Step 4: If it doesn't help, this person may have intrinsic renal disease.

Also, an excellent post on maintenance fluids here: http://vitualis.wordpress.com/2006/05/01/maintenance-iv-fluids-in-euvolaemic-adults/

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