Slide 1: Let’s talk about I/Os (intake and output)! I/Os are a part of life on the medical wards and are particularly important for patients who are undergoing diuresis.

Question: You just gave a dose of lasix at 8 am, when do you loop back to see if it’s working? A. After 1 hour, B. After 2-6 hours, C. “Running the list” at 4 pm, D. AM rounds tomorrow

Slide 2: A and B are correct! You can check a urine sodium at 1-2 hours to ensure it is greater than 50-70 mmol/L. You can also assess urine output at 2-6 hours to see if the urine output is greater than 150 mL/hr.

Slide 3: Not an effective dose? No need to wait for the next scheduled dose to increase! With a logarithmic dose-response curve, doubling the dose of diuretic is usually required for improved diuretic response.

Slide 4: For more great info on adequate diuresis, check out our 6/24/2020 podcast: “5 Pearls on Inpatient Heart Failure”

Slide 5: Sources of input should include: medications that require fluid for preparation and administration, tube feeds, fluids consumed as beverages: water, coffee, soda, etc., fluids consumed with food: milk in cereal, broth soup, etc., any IV fluids including resuscitation fluids, maintenance fluids, and blood products.

In addition to urine, other measures sources of output may include: ileostomy or colostomy drainage, chest tube drainage, blood loss, vomit, wound drainage.

Slide 6: Keeping track of I/Os is a difficult task! Here are some tips to aid in more accurate tracking:

Be sure to place an order in the EMR for strict I/Os and a fluid restriction if indicated.

Always be sure to verbally communicate your plan with the RN. Show your thanks!

Involve the patient. Review your plan and explain how measuring I/Os will help their care.

Don’t forget about beverages or food brought in by visitors who might be unaware of the need to track I/Os.

In some critically ill patients, it may be appropriate to use a Foley catheter to measure output.

A PureWick catheter may be helpful for general medical patients who are incontinent of urine.

Slide 7: Key Takeaways. When measure I/Os, there are many potential sources of error. Clinical monitoring of diuretic response is multifactorial – more than just monitoring I/Os – which may also include: daily weight trend, urine sodium trend, and clinical volume assessment.


  • Meddings J, Saint S, Fowler KE, Gaies E, Hickner A, Krein SL, Bernstein SJ. The Ann Arbor Criteria for Appropriate Urinary Catheter Use in Hospitalized Medical Patients: Results Obtained by Using the RAND/UCLA Appropriateness Method. Ann Intern Med. 2015 May 5;162(9 Suppl):S1-34. PMID 25938928.

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