{
  "slug": "ng-tube-fluid-replacement",
  "title": "NG Tube Output Fluid Replacement Calculator",
  "heading": "NG/Drain Output Fluid Replacement Calculator",
  "category": "fitness-health",
  "url": "https://www.revenuelab.fyi/toolbox/ng-tube-fluid-replacement",
  "summary": "Replace ongoing nasogastric or drain losses on top of maintenance fluids.",
  "description": "Nasogastric suction, high-output ostomies, and surgical drains remove fluid and electrolytes that maintenance fluid orders do not account for, and failing to replace them leads to progressive volume depletion and electrolyte derangement, classically hypokalemic, hypochloremic metabolic alkalosis from gastric losses. Standard practice replaces measured output, typically on a delayed schedule (replacing the prior period's output over the current period) using a fluid similar in electrolyte composition to what was lost — normal saline with potassium chloride is a common choice for gastric output given its high chloride and potassium content. This calculator totals a shift's measured output and converts it into an hourly replacement rate to add on top of the separately ordered maintenance fluids; it does not select the replacement fluid composition, which should match the source (gastric, biliary, pancreatic, ileostomy) and be confirmed against institutional protocol and electrolyte trends. This tool is for education and workflow support only — not medical advice. Always verify results with a clinician and use clinical judgment alongside your institution's protocols.",
  "formula": "Replacement rate (mL/hr) = total measured output (mL) ÷ replacement period (hr), added to maintenance fluid rate.",
  "dateModified": "2026-09-30",
  "run_url": "https://www.revenuelab.fyi/api/public/calc?tool=ng-tube-fluid-replacement",
  "inputs": [
    {
      "id": "outputMl",
      "label": "Measured output over the period",
      "kind": "number",
      "hint": null,
      "default": 480,
      "unit": "mL",
      "min": 0,
      "max": null
    },
    {
      "id": "periodHr",
      "label": "Measurement period",
      "kind": "number",
      "hint": null,
      "default": 8,
      "unit": "hr",
      "min": 1,
      "max": 24
    },
    {
      "id": "maintenanceRate",
      "label": "Current maintenance rate (optional)",
      "kind": "number",
      "hint": null,
      "default": 75,
      "unit": "mL/hr",
      "min": 0,
      "max": null
    },
    {
      "id": "replacementFraction",
      "label": "Fraction of output to replace",
      "kind": "number",
      "hint": null,
      "default": 100,
      "unit": "%",
      "min": 0,
      "max": 150
    }
  ],
  "outputs": [
    {
      "id": "replacementRate",
      "label": "Replacement rate to add",
      "format": "decimal",
      "hint": null,
      "primary": true
    },
    {
      "id": "totalRate",
      "label": "Combined total infusion rate",
      "format": "decimal",
      "hint": null,
      "primary": false
    },
    {
      "id": "dailyOutputProjected",
      "label": "Projected 24-hour output at this rate",
      "format": "number",
      "hint": null,
      "primary": false
    }
  ],
  "worked_example": {
    "inputs": [
      "Measured output over the period: 480 mL",
      "Measurement period: 8 hr",
      "Current maintenance rate (optional): 75 mL/hr",
      "Fraction of output to replace: 100 %"
    ],
    "outputs": [
      "Replacement rate to add: 60",
      "Combined total infusion rate: 135",
      "Projected 24-hour output at this rate: 1,440"
    ]
  },
  "how_to": {
    "title": "How to use this",
    "steps": [
      "Enter measured output over the period (mL).",
      "Enter measurement period (hr).",
      "Enter current maintenance rate (optional) (mL/hr).",
      "Enter fraction of output to replace (%).",
      "Read your replacement rate to add on the right — it updates as you type.",
      "Hit Share to keep the scenario or send it to someone."
    ]
  },
  "scenarios": [
    {
      "name": "Conservative",
      "description": "Lower-end numbers — what if things land soft?",
      "values": {
        "outputMl": 290,
        "periodHr": 5,
        "maintenanceRate": 45,
        "replacementFraction": 60
      }
    },
    {
      "name": "Typical",
      "description": "Defaults — the most common real-world setup.",
      "values": {
        "outputMl": 480,
        "periodHr": 8,
        "maintenanceRate": 75,
        "replacementFraction": 100
      }
    },
    {
      "name": "Ambitious",
      "description": "Higher-end numbers — what if things really pop?",
      "values": {
        "outputMl": 770,
        "periodHr": 13,
        "maintenanceRate": 120,
        "replacementFraction": 150
      }
    }
  ],
  "limitations": [
    "Population formulas describe averages; individual bodies vary, especially at the extremes of height, age, or muscle mass.",
    "Results do not account for medical conditions, medication, or pregnancy.",
    "Use this as a directional reference, not a diagnosis — talk to a clinician before acting on it."
  ],
  "faq": [
    {
      "q": "What fluid should replace NG output?",
      "a": "Gastric output is rich in chloride, hydrogen, and potassium, so 0.45% or 0.9% normal saline with added potassium chloride is a common choice, but this varies by institution and the specific source of output (gastric vs. biliary vs. pancreatic vs. ileostomy each has a different electrolyte profile). Confirm with your pharmacy or protocol rather than assuming one fluid fits all drains."
    },
    {
      "q": "Should I replace 1:1 or on a delay?",
      "a": "Many protocols replace the prior shift's or prior period's measured output over the following period, rather than trying to real-time match losses, since output can be sporadic. Replacing over the following 4-8 hours as this calculator models is a common, practical approach."
    },
    {
      "q": "Why might I replace less than 100% of output?",
      "a": "In a fluid-overloaded patient, or one whose losses are decreasing, replacing at 50-75% of measured output can be appropriate to avoid overcorrection, especially if serum electrolytes are being trended and adjusted concurrently. This should be a clinical decision, not a default."
    },
    {
      "q": "Does this replace maintenance fluids or add to them?",
      "a": "It adds to them. NG or drain output replacement addresses ongoing abnormal losses; maintenance fluids address baseline physiologic needs independent of those losses. Both are typically ordered separately and summed to get total infusion rate, as this calculator does."
    }
  ],
  "related": [
    "https://www.revenuelab.fyi/toolbox/maintenance-fluid-rate",
    "https://www.revenuelab.fyi/toolbox/fena-calculator",
    "https://www.revenuelab.fyi/toolbox/osmolar-gap"
  ],
  "license": "CC-BY-4.0",
  "citation": "RevenueLab — NG Tube Output Fluid Replacement Calculator (https://www.revenuelab.fyi/toolbox/ng-tube-fluid-replacement)"
}