Intake and Output (I&O) is a fundamental measurement tool used in healthcare, primarily in hospital settings, to track a patient’s fluid balance. It involves meticulously recording all fluids that enter and leave the body over a specific period. This systematic monitoring provides medical teams with quantitative data regarding the patient’s hydration status and organ function, guiding decisions about fluid administration and medication management.
Defining Intake and Output
Intake refers to all liquids entering the body, regardless of the route of administration, and is always measured in milliliters (mL). This includes all oral fluids consumed by the patient, such as water, juice, milk, soup, and melted items like ice cream or gelatin. Ice chips are counted as half of their volume when calculating intake, as they are mostly air. Intake also encompasses all intravenous (IV) fluids, including medication diluents, as well as nutritional formulas delivered through a feeding tube (enteral fluids).
Output is the measurement of all fluids that leave the body and can be accurately quantified. The most common output measured is urine, which is collected from bedpans, urinals, or catheter bags and measured with a graduated container. Other measurable output includes liquid stool from diarrhea, vomitus, and drainage from surgical sites or wounds. Output from specialized devices, such as nasogastric tubes or chest tubes, is also collected and recorded in milliliters.
Why Medical Teams Track I&O
Tracking I&O allows healthcare providers to assess the patient’s fluid balance, which is the relationship between the fluid taken in and the fluid lost. A significant difference between the two totals can signal fluid overload or dehydration, conditions that can quickly destabilize a patient. Patients with congestive heart failure or kidney disease must be monitored closely to prevent fluid retention that can worsen their condition.
The I&O data helps evaluate the effectiveness of treatments, such as IV fluid administration or the use of diuretics to eliminate excess water. Inadequate urine output, despite normal fluid intake, can indicate poor kidney function or acute kidney injury. By calculating the fluid balance over a 24-hour period, the medical team can adjust fluid restrictions or IV fluid rates, promoting stability and recovery.
How I&O is Measured and Recorded
Measuring I&O requires cooperation between the nursing staff, the patient, and family members. All measurements are taken using calibrated containers to ensure accuracy, and the volumes are recorded in milliliters. For output not easily collected, such as wound drainage on a dressing, the difference between the dressing’s dry weight and saturated weight is used for estimation, as one gram is equivalent to one milliliter of fluid.
The recorded I&O events are documented on a specialized fluid balance chart, which may be a paper form or part of the electronic health record. Entries are made immediately after the fluid is consumed or eliminated, along with the time of the event. Totals are calculated at set intervals, typically at the end of each nursing shift, and a final 24-hour total is compiled for the medical provider to review.