Strict I&O
Formal Definition
A nursing order requiring precise measurement and documentation of all fluid intake (oral, IV, enteral tube feeding, blood products, medications) and all fluid output (urine, emesis, stool, drain output, NG suction, wound drainage) for a hospitalized patient, typically summed and totaled every shift (8h or 12h) and totaled at 24h; allows the team to track fluid balance, assess response to diuretics, monitor renal function, and detect early signs of fluid overload or dehydration; quantified net intake-output (positive, negative, or zero) drives clinical decisions.
How It's Used on the Ward
"Strict I's and O's" or "I&Os" — when the team needs to know exactly how much fluid is going in and coming out; the patient's urine is measured (often via Foley catheter with urometer), emesis is caught and measured, oral fluids are documented by nursing (purely by patient report or estimation); ICU and step-down patients are routinely on strict I&O.
Example
""CHF exacerbation patient on IV furosemide: 'She's on strict I&Os, and the 24h tally showed net negative 1.8 L — 2.4 L in, 4.2 L out. Weights down 2.1 kg from yesterday. Looking like good diuresis.' Critical for tracking effectiveness of diuretic therapy in heart failure and for monitoring renal function in AKI.""
Clinical Context
Practical implementation: requires patient education and nursing compliance — patients must report oral intake (challenging), urine output measured (often requires Foley or bedside commode with measurement), emesis caught and measured, all IV fluids documented. Critical populations: CHF (monitoring response to diuresis — goal net negative), AKI (monitoring urine output — oliguria <0.5 mL/kg/h is concerning), post-op (third-spacing fluid shifts, monitoring recovery), DKA/HHS (aggressive rehydration with monitoring), neurosurgery patients (SIADH, cerebral salt wasting, DI). Limitations: oral intake often estimated rather than measured; intra-operative fluid may not be perfectly tracked; accuracy drops outside ICU. Alternatives: daily weights (when I&O not feasible, daily weights are simpler and more reliable for fluid-balance trending in chronic CHF patients; 1 kg weight change ≈ 1 L fluid shift). Common errors: forgetting to add IV medication volumes, missing ostomy output, missing drain output, RN estimation without actual measurement.