LIVE

Maintenance fluids

Compute Holliday–Segar 1957 daily maintenance water from weight, plus the corresponding hourly milliliters.

LIVE $0.005 USDC GET /api/calc/maintenance_fluids

Markdown: /docs/maintenance-fluids.md · Canonical: https://magentlab.com/docs/maintenance-fluids

Not a medical device. Not a diagnosis, dose, or listing recommendation.

What it computes

Compute Holliday–Segar 1957 daily maintenance water from weight, plus the corresponding hourly milliliters.

When to use

When an agent needs the 1957 100/50/20 mL/kg daily maintenance-water arithmetic and must not invent a volume or apply the later 4-2-1 rule.

When not to use

• Not a treatment order or IV prescription. Does not choose fluid type, electrolyte additives, or infusion-rate safety limits.
• Uses the paper's daily 100/50/20 mL/kg volumes. The later bedside 4-2-1 mL/kg/h rule is an hourly approximation and is not applied here.
• Estimates typical pediatric parenteral maintenance water only. Does not add fever, ongoing losses, or renal impairment.

Formula

daily_ml = 100*min(kg,10) + 50*max(0, min(kg,20)-10) + 20*max(0, kg-20); hourly_ml = daily_ml / 24

Citation

Title

The maintenance need for water in parenteral fluid therapy

Authors

Holliday MA, Segar WE

Source

Pediatrics. 1957;19(5):823-832

DOI

10.1542/peds.19.5.823

Worked example

Try

Opens the live endpoint. Unpaid browser requests show the paywall; agents should send Accept: application/json.

/api/calc/maintenance_fluids?weight_kg=30

Full URL: https://api.magentlab.com/api/calc/maintenance_fluids?weight_kg=30

x402 V2 curl

Expect HTTP 402 and a PAYMENT-REQUIRED header until you retry with PAYMENT-SIGNATURE. Incomplete query params return HTTP 400 before any quote or charge. HTTP 503 after a signature: retry the same PAYMENT-SIGNATURE — that is not a new 402.

curl -i -H "Accept: application/json" "https://api.magentlab.com/api/calc/maintenance_fluids?weight_kg=30"

Cursor mcp.json

Intended config for @magent/mcp. This is not npm @x402/fetch (a payment fetch wrapper).

{
  "mcpServers": {
    "magent": {
      "args": [
        "-y",
        "@magent/mcp"
      ],
      "command": "npx",
      "env": {
        "X402_PRIVATE_KEY": "0xYOUR_SPENDING_KEY"
      }
    }
  }
}

Parameters

Bulk (POST)

POST the same path with a JSON items array. Price is n times the GET unit. Invalid items return HTTP 400 before settlement.

POST /api/calc/maintenance_fluids Max 25 unit_amount * n PREVIEW

• 1 to 25 items. Each item uses the same keys as the GET query parameters.
• The first invalid item fails the whole request (index in the 400 JSON). You are not charged.
• HTTP 200 is {count, path, items}. Each items[i] is the GET 200 body for that row.
• Catalog misses (empty matches, found=false) stay paid 200s inside that slot.
• x402 resource URL is this path plus n and body_sha256. Browsers that prefer text/html get the same paywall as GET; Pay retries POST with the same items.

Example request (fixture)

{
  "items": [
    {
      "weight_kg": "30"
    },
    {
      "weight_kg": "30"
    }
  ]
}

Open bulk paywall →

Opens a two-item fixture on the API host. Unpaid browsers get the same MetaMask paywall as GET; Pay retries POST with those items.

Example 200 (fixture)

{
  "count": 2,
  "path": "/api/calc/maintenance_fluids",
  "items": [
    {
      "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "citation": {
        "authors": "Holliday MA, Segar WE",
        "doi": "10.1542/peds.19.5.823",
        "id": "holliday-segar-1957",
        "source": "Pediatrics. 1957;19(5):823-832",
        "title": "The maintenance need for water in parenteral fluid therapy"
      },
      "formula": "holliday_segar",
      "formula_expression": "daily_ml = 100*min(kg,10) + 50*max(0, min(kg,20)-10) + 20*max(0, kg-20); hourly_ml = daily_ml / 24",
      "weight_kg": 30.0,
      "daily_ml": 1700,
      "hourly_ml": 70.8
    },
    {
      "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "citation": {
        "authors": "Holliday MA, Segar WE",
        "doi": "10.1542/peds.19.5.823",
        "id": "holliday-segar-1957",
        "source": "Pediatrics. 1957;19(5):823-832",
        "title": "The maintenance need for water in parenteral fluid therapy"
      },
      "formula": "holliday_segar",
      "formula_expression": "daily_ml = 100*min(kg,10) + 50*max(0, min(kg,20)-10) + 20*max(0, kg-20); hourly_ml = daily_ml / 24",
      "weight_kg": 30.0,
      "daily_ml": 1700,
      "hourly_ml": 70.8
    }
  ]
}

Response

Example JSON

Machine form of the same example. Frozen fixture. Not a live lookup.

{
  "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
  "citation": {
    "authors": "Holliday MA, Segar WE",
    "doi": "10.1542/peds.19.5.823",
    "id": "holliday-segar-1957",
    "source": "Pediatrics. 1957;19(5):823-832",
    "title": "The maintenance need for water in parenteral fluid therapy"
  },
  "formula": "holliday_segar",
  "formula_expression": "daily_ml = 100*min(kg,10) + 50*max(0, min(kg,20)-10) + 20*max(0, kg-20); hourly_ml = daily_ml / 24",
  "weight_kg": 30.0,
  "daily_ml": 1700,
  "hourly_ml": 70.8
}

Errors

Related tools

• BMI — Compute Keys/Quetelet body-mass index from height and weight, plus a WHO adult band.
• Devine IBW — Compute Devine ideal body weight and 0.4 adjusted body weight from height, sex, and actual weight.
• Harris-Benedict BEE — Compute Harris–Benedict 1919 basal energy expenditure in kcal/day from height, weight, age, and sex.

Also searched as

• Holliday Segar
• maintenance fluids
• pediatric maintenance water
• 100 50 20 fluids
• Holliday-Segar water

Payment

Required query parameters must be present and valid. Invalid params return HTTP 400 JSON before settlement. magent does not charge. Fix the params, then request a new 402 quote for that complete URL. Catalog misses (empty matches, found=false) are valid paid 200s. Unpaid valid requests return HTTP 402 with a base64 PAYMENT-REQUIRED header. HTTP 503 is not a new quote: retry the same PAYMENT-SIGNATURE. Full handshake and shared payment errors: Payments.

Guarantees

• Invalid query parameters return HTTP 400 before settlement. You are not charged.
• Settlement finishes before the tool executes (paymentFlow upfront). Uncertain or failed settlement fails closed (HTTP 503). Retry the same PAYMENT-SIGNATURE.
• HTTP 402 is unpaid only. Do not sign a second authorization because of a 503.
• Execution is timeout-bounded and concurrency-capped.
• Calculator inputs are stored encrypted for allowlisted operators (Magent Console). They are not in public logs, SSH lookups, catalog, or rollups. Request logs store path without query.