Strict I&O
Formal Definition
"I&O" — strict intake and output documentation, an inpatient nursing order requiring every source of fluid the patient takes in (PO fluids, IV fluids, IV medications, NG/J-tube feeds, blood products) and every source of fluid the patient puts out (urine output, stool volume/emesis, J/P/drain output, blood loss) to be measured and charted, typically hour-by-hour with a 24-hour total reconciled at midnight; used to monitor fluid balance, urine output as a marker of renal perfusion or AKI, hydration status, diuresis response, and effectiveness of fluid removal in patients with CHF or AKI.
How It's Used on the Ward
"Strict I&O" — the nursing order that requires meticulous fluid tracking; "I&O 24-hour total" — the cumulative net fluid balance summary documented each midnight; "negative balance" — output exceeds intake (patient is losing fluid; diuresed or dehydrated); "positive balance" — output less than intake (fluid overload, third-spacing, or kidney not making urine).
Example
""Hospitalized 76-year-old woman with acute decompensated heart failure, ejection fraction 30%, presenting with 3+ pitting edema and 12-pound weight gain. Admitting orders include: 'Strict I&O. Daily weights, q4h vital signs, net fluid balance documentation, target urine output >0.5 mL/kg/hr.' Over 72 hours: total intake 4.2 L (IV fluids, medications, PO), total output 6.8 L (urine 6.2 L with IV diuresis, stool 0.6 L). Net negative 2.6 L; reduction in edema, 4-pound weight loss, improved dyspnea. Patient euvolemic by hospital day 5.""
Clinical Context
Standard I&O order details: (1) PO fluids — measured in cc or mL with each ingestion (water cup 240 mL, etc., estimated or measured; nursing careful). (2) IV fluids — running rates on the IV pole are easy to track (1 L NS at 75 mL/hr = 75 mL/hr intake for 24 hours), but flush volumes add up (10 mL flush q6h with each IV med = 40 mL/day). (3) IV medications — order-set medications should be documented with their diluent volume. (4) Enteral feeds (tube feeds) — continuous or bolus rates trackable. (5) Output: urine — frequent voiding (measured in hat or graduated container), Foley catheter hourly; stool — usually measured on diaper weight or hourly in special cases; emesis — measured; drains (JP, NG, chest tube, hemovac) — measured qshift; blood loss — recorded if present. Common clinical scenarios: AKI workup (urine output <0.5 mL/kg/hr is AKI criterion); severe CHF (tracking effective diuresis); DKA (insensible losses, fluid resuscitation); post-op major surgery (third-spacing losses, return to baseline); TPN nutrition support (careful to not over-fluid-resuscitate). 24-hour I&O rec: nursing reassesses net balance at midnight shift change; positive cumulative balance over days warrants diuresis adjustment or fluid balance review.