Respiratory · LIVE

ROX index

Compute the ROX index as pulse-oximetry SpO2 percent divided by inspired oxygen fraction, then divided by respiratory rate.

LIVE $0.005 USDC GET /api/calc/rox

Markdown: /docs/rox.md · Canonical: https://magentlab.com/docs/rox

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

What it computes

Compute the ROX index as pulse-oximetry SpO2 percent divided by inspired oxygen fraction, then divided by respiratory rate.

When to use

When an agent needs (SpO2/FiO2)/respiratory_rate and must not invent HFNC success or failure, a PaO2/FiO2 ratio, or RSBI.

When not to use

• Not a diagnosis and not a ventilation order.
• Magent does not apply the 4.88 12-hour HFNC success/failure cutoff; that threshold is time-contextual in Roca 2016.
• This is not the PaO2/FiO2 (P/F) ratio.
• This is not RSBI (respiratory rate divided by tidal volume).

Formula

rox = (spo2_percent / fio2) / respiratory_rate

Citation

Title

Predicting success of high-flow nasal cannula in pneumonia patients with hypoxemic respiratory failure: The utility of the ROX index

Authors

Roca O, Messika J, Caralt B, García-de-Acilu M, Sztrymf B, Ricard JD, Masclans JR

Source

J Crit Care. 2016;35:200-205

DOI

10.1016/j.jcrc.2016.05.022

Worked example

Also searched as

• ROX index
• Roca ROX
• SpO2/FiO2 over respiratory rate
• HFNC ROX index
• respiratory rate oxygenation
• SpO2 FiO2 RR index
• ROX HFNC

Try

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

/api/calc/rox?spo2_percent=95&fio2=0.21&respiratory_rate=20

Full URL: https://api.magentlab.com/api/calc/rox?spo2_percent=95&fio2=0.21&respiratory_rate=20

Call

Expect HTTP 402 until you retry with PAYMENT-SIGNATURE. Incomplete query params return HTTP 400 before any quote or charge.

curl -i -H "Accept: application/json" "https://api.magentlab.com/api/calc/rox?spo2_percent=95&fio2=0.21&respiratory_rate=20"

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/rox 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": [
    {
      "fio2": "0.21",
      "respiratory_rate": "20",
      "spo2_percent": "95"
    },
    {
      "fio2": "0.21",
      "respiratory_rate": "20",
      "spo2_percent": "95"
    }
  ]
}

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/rox",
  "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": "Roca O, Messika J, Caralt B, García-de-Acilu M, Sztrymf B, Ricard JD, Masclans JR",
        "doi": "10.1016/j.jcrc.2016.05.022",
        "id": "roca-2016",
        "source": "J Crit Care. 2016;35:200-205",
        "title": "Predicting success of high-flow nasal cannula in pneumonia patients with hypoxemic respiratory failure: The utility of the ROX index"
      },
      "formula": "rox",
      "formula_expression": "rox = (spo2_percent / fio2) / respiratory_rate",
      "fio2": 0.21,
      "respiratory_rate": 20,
      "rox": 22.62,
      "spo2_percent": 95.0
    },
    {
      "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": "Roca O, Messika J, Caralt B, García-de-Acilu M, Sztrymf B, Ricard JD, Masclans JR",
        "doi": "10.1016/j.jcrc.2016.05.022",
        "id": "roca-2016",
        "source": "J Crit Care. 2016;35:200-205",
        "title": "Predicting success of high-flow nasal cannula in pneumonia patients with hypoxemic respiratory failure: The utility of the ROX index"
      },
      "formula": "rox",
      "formula_expression": "rox = (spo2_percent / fio2) / respiratory_rate",
      "fio2": 0.21,
      "respiratory_rate": 20,
      "rox": 22.62,
      "spo2_percent": 95.0
    }
  ]
}

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": "Roca O, Messika J, Caralt B, García-de-Acilu M, Sztrymf B, Ricard JD, Masclans JR",
    "doi": "10.1016/j.jcrc.2016.05.022",
    "id": "roca-2016",
    "source": "J Crit Care. 2016;35:200-205",
    "title": "Predicting success of high-flow nasal cannula in pneumonia patients with hypoxemic respiratory failure: The utility of the ROX index"
  },
  "formula": "rox",
  "formula_expression": "rox = (spo2_percent / fio2) / respiratory_rate",
  "fio2": 0.21,
  "respiratory_rate": 20,
  "rox": 22.62,
  "spo2_percent": 95.0
}

Client errors (HTTP 400)

Invalid params return 400 without charge. Shared HTTP 402 and 503 meanings: Payments.

Related tools

• PaO2/FiO2 ratio — Compute the PaO2/FiO2 ratio as arterial PO2 in mm Hg divided by inspired oxygen fraction.
• Rapid shallow breathing index — Compute the Yang and Tobin rapid shallow breathing index as respiratory rate in breaths/min divided by tidal volume in liters.

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. Stdio MCP: /docs/mcp.

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.