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San Francisco Syncope Rule

Compute the San Francisco Syncope Rule (CHESS) criterion count and rule-positive flag from published cutoffs.

LIVE $0.005 USDC GET /api/calc/sf_syncope

Markdown: /docs/sf-syncope.md · Canonical: https://magentlab.com/docs/sf-syncope

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

What it computes

Compute the San Francisco Syncope Rule (CHESS) criterion count and rule-positive flag from published cutoffs.

When to use

When an agent needs the published CHESS arithmetic and must not invent a disposition from a syncope narrative.

When not to use

• Not a disposition protocol. Rule-positive means any CHESS criterion, not a diagnosis.
• Derivation cohort was emergency-department syncope. magent applies the published hematocrit <30% and SBP <90 mm Hg cutoffs; it does not interpret an ECG.

Formula

CHESS = chf + hematocrit_lt_30 + abnormal_ecg + shortness_of_breath + systolic_bp_lt_90; rule-positive if score ≥ 1; max 5

Citation

Title

Derivation of the San Francisco Syncope Rule to predict patients with short-term serious outcomes

Authors

Quinn JV, Stiell IG, McDermott DA, Sellers KL, Kohn MA, Wells GA

Source

Ann Emerg Med. 2004;43(2):224-232

DOI

10.1016/S0196-0644(03)00823-0

Worked example

Try

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

/api/calc/sf_syncope?chf=false&hematocrit_percent=40&abnormal_ecg=false&shortness_of_breath=false&systolic_bp_mm_hg=120

Full URL: https://api.magentlab.com/api/calc/sf_syncope?chf=false&hematocrit_percent=40&abnormal_ecg=false&shortness_of_breath=false&systolic_bp_mm_hg=120

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/sf_syncope?chf=false&hematocrit_percent=40&abnormal_ecg=false&shortness_of_breath=false&systolic_bp_mm_hg=120"

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/sf_syncope 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": [
    {
      "abnormal_ecg": "false",
      "chf": "false",
      "hematocrit_percent": "40",
      "shortness_of_breath": "false",
      "systolic_bp_mm_hg": "120"
    },
    {
      "abnormal_ecg": "false",
      "chf": "false",
      "hematocrit_percent": "40",
      "shortness_of_breath": "false",
      "systolic_bp_mm_hg": "120"
    }
  ]
}

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/sf_syncope",
  "items": [
    {
      "components": [
        {
          "factor": "chf",
          "points": 0,
          "present": false
        },
        {
          "value": 40.0,
          "factor": "hematocrit_lt_30",
          "points": 0,
          "present": false
        },
        {
          "factor": "abnormal_ecg",
          "points": 0,
          "present": false
        },
        {
          "factor": "shortness_of_breath",
          "points": 0,
          "present": false
        },
        {
          "value": 120.0,
          "factor": "systolic_bp_lt_90",
          "points": 0,
          "present": false
        }
      ],
      "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": "Quinn JV, Stiell IG, McDermott DA, Sellers KL, Kohn MA, Wells GA",
        "doi": "10.1016/S0196-0644(03)00823-0",
        "id": "quinn-2004",
        "source": "Ann Emerg Med. 2004;43(2):224-232",
        "title": "Derivation of the San Francisco Syncope Rule to predict patients with short-term serious outcomes"
      },
      "formula": "sf_syncope",
      "formula_expression": "CHESS = chf + hematocrit_lt_30 + abnormal_ecg + shortness_of_breath + systolic_bp_lt_90; rule-positive if score ≥ 1; max 5",
      "max_score": 5,
      "score": 0,
      "hematocrit_percent": 40.0,
      "rule_positive": false,
      "systolic_bp_mm_hg": 120.0
    },
    {
      "components": [
        {
          "factor": "chf",
          "points": 0,
          "present": false
        },
        {
          "value": 40.0,
          "factor": "hematocrit_lt_30",
          "points": 0,
          "present": false
        },
        {
          "factor": "abnormal_ecg",
          "points": 0,
          "present": false
        },
        {
          "factor": "shortness_of_breath",
          "points": 0,
          "present": false
        },
        {
          "value": 120.0,
          "factor": "systolic_bp_lt_90",
          "points": 0,
          "present": false
        }
      ],
      "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": "Quinn JV, Stiell IG, McDermott DA, Sellers KL, Kohn MA, Wells GA",
        "doi": "10.1016/S0196-0644(03)00823-0",
        "id": "quinn-2004",
        "source": "Ann Emerg Med. 2004;43(2):224-232",
        "title": "Derivation of the San Francisco Syncope Rule to predict patients with short-term serious outcomes"
      },
      "formula": "sf_syncope",
      "formula_expression": "CHESS = chf + hematocrit_lt_30 + abnormal_ecg + shortness_of_breath + systolic_bp_lt_90; rule-positive if score ≥ 1; max 5",
      "max_score": 5,
      "score": 0,
      "hematocrit_percent": 40.0,
      "rule_positive": false,
      "systolic_bp_mm_hg": 120.0
    }
  ]
}

Response

Example JSON

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

{
  "components": [
    {
      "factor": "chf",
      "points": 0,
      "present": false
    },
    {
      "value": 40.0,
      "factor": "hematocrit_lt_30",
      "points": 0,
      "present": false
    },
    {
      "factor": "abnormal_ecg",
      "points": 0,
      "present": false
    },
    {
      "factor": "shortness_of_breath",
      "points": 0,
      "present": false
    },
    {
      "value": 120.0,
      "factor": "systolic_bp_lt_90",
      "points": 0,
      "present": false
    }
  ],
  "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": "Quinn JV, Stiell IG, McDermott DA, Sellers KL, Kohn MA, Wells GA",
    "doi": "10.1016/S0196-0644(03)00823-0",
    "id": "quinn-2004",
    "source": "Ann Emerg Med. 2004;43(2):224-232",
    "title": "Derivation of the San Francisco Syncope Rule to predict patients with short-term serious outcomes"
  },
  "formula": "sf_syncope",
  "formula_expression": "CHESS = chf + hematocrit_lt_30 + abnormal_ecg + shortness_of_breath + systolic_bp_lt_90; rule-positive if score ≥ 1; max 5",
  "max_score": 5,
  "score": 0,
  "hematocrit_percent": 40.0,
  "rule_positive": false,
  "systolic_bp_mm_hg": 120.0
}

Errors

Related tools

• Glasgow Coma Scale — Compute the Glasgow Coma Scale as the sum of caller-assigned eye, verbal, and motor integers. The 1974 or 1976 edition is required.

Also searched as

• San Francisco Syncope Rule
• SFSR
• CHESS syncope
• Quinn syncope rule

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.