# San Francisco Syncope Rule Status: LIVE Price: $0.005 USDC `GET /api/calc/sf_syncope` HTML: https://magentlab.com/docs/sf-syncope Markdown: https://magentlab.com/docs/sf-syncope.md 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 Derivation of the San Francisco Syncope Rule to predict patients with short-term serious outcomes Quinn JV, Stiell IG, McDermott DA, Sellers KL, Kohn MA, Wells GA Ann Emerg Med. 2004;43(2):224-232 DOI: [10.1016/S0196-0644(03)00823-0](https://doi.org/10.1016/S0196-0644(03)00823-0) ## Worked example ### All CHESS criteria negative Given: `abnormal_ecg=false, chf=false, hematocrit_percent=40, shortness_of_breath=false, systolic_bp_mm_hg=120` 1. CHF absent; hematocrit 40% (≥30); ECG not abnormal; no dyspnea; SBP 120 (≥90) 2. Score = 0; rule-positive false ## Parameters - `chf` (boolean, required): History of congestive heart failure (C). true or false. - `hematocrit_percent` (number, required): Hematocrit in percent (10-70). Scores 1 when <30; 30 is negative. - `abnormal_ecg` (boolean, required): Abnormal ECG (E). true or false. Caller-assigned; magent does not read tracings. - `shortness_of_breath` (boolean, required): Shortness of breath (S). true or false. - `systolic_bp_mm_hg` (number, required): Systolic BP in mm Hg (50-250). Scores 1 when <90; 90 is negative. ## 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. Method: `POST /api/calc/sf_syncope` Max items: 25 Price: unit_amount * n (unit 5000 atomic) Status: 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: ```json { "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" } ] } ``` Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/sf-syncope Example 200: ```json { "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 fields - `formula` (string): sf_syncope - `formula_expression` (string): Exact expression used - `score` (integer): Count of positive CHESS criteria (0-5) - `max_score` (integer): Always 5 - `rule_positive` (boolean): true when score ≥ 1 (any CHESS criterion). Not a diagnosis. - `hematocrit_percent` (number): Hematocrit used for the <30 cutoff - `systolic_bp_mm_hg` (number): Systolic BP used for the <90 cutoff - `components` (array): Per-factor points - `citation` (object): Ann Emerg Med 2004 citation - `disclaimer` (string): Not-a-device notice ## Example JSON Frozen fixture. Not a live lookup. ```json { "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 - HTTP 400 `invalid_flag`: boolean clinical flags must be true or false Returned before settlement; you are not charged. - HTTP 400 `invalid_hematocrit`: hematocrit_percent must be a number from 10 to 70. Returned before settlement; you are not charged. - HTTP 400 `invalid_systolic_bp`: systolic_mm_hg or systolic_bp_mm_hg must be a number from 50 to 250. Returned before settlement; you are not charged. - HTTP 400 `invalid_items`: POST body must be a JSON object with only an items array Returned before settlement; you are not charged. - HTTP 400 `invalid_item_count`: items must be an array of 1 to 25 objects Returned before settlement; you are not charged. - HTTP 400 `invalid_item`: each items entry must be a JSON object Returned before settlement; you are not charged. - HTTP 402 `payment_required`: Missing or invalid PAYMENT-SIGNATURE; decode the PAYMENT-REQUIRED header - HTTP 409 `payment_in_progress`: The same authorization nonce is already being settled; retry shortly - HTTP 429 `rate_limited`: Too many requests from this client - HTTP 503 `settlement_uncertain`: Settlement is unconfirmed; retry with the same PAYMENT-SIGNATURE - HTTP 503 `settle_failed`: Settlement failed; retry with the same PAYMENT-SIGNATURE shortly - HTTP 503 `facilitator_unavailable`: Payment facilitator unavailable - HTTP 503 `facilitator_misconfigured`: Payment facilitator is not configured - HTTP 503 `facilitator_unauthorized`: Payment facilitator rejected credentials - HTTP 503 `ledger_unavailable`: Payment ledger unavailable - HTTP 503 `payment_unavailable`: Payment processing unavailable ## Related tools - [Glasgow Coma Scale](https://magentlab.com/docs/gcs) — 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. - GET the tool with Accept: application/json (do not send Accept: text/html unless you want the human paywall). - HTTP 402 means you have not paid. Decode the base64 PAYMENT-REQUIRED header. HTTP 503 is not a new quote. - Sign EIP-3009 (scheme exact, assetTransferMethod eip3009) with validBefore = now + accepts[0].maxTimeoutSeconds (600 seconds). That window starts when you sign and must cover wallet confirmation plus CDP verify and settle. Magent retries transient facilitator 429/5xx before answering. Do not send upto or batch-settlement payloads; magent does not offer those schemes. - Retry the same URL with PAYMENT-SIGNATURE (base64 JSON echoing accepted, payload, and extensions when present). - Success is HTTP 200 JSON plus PAYMENT-RESPONSE. Settlement happens before the tool runs. HTTP 503 settlement_uncertain or settle_failed: retry the same PAYMENT-SIGNATURE. Mint a new nonce only after a new HTTP 402. - offered `exact` on eip155:8453: Fixed-price USDC on Base. The buyer authorizes the advertised amount (EIP-3009). magent settles before the tool runs (paymentFlow upfront). extra.assetTransferMethod=eip3009 extra.paymentFlow=upfront. - not offered `upto`: Not offered. Usage-based: buyer authorizes a ceiling, seller settles the actual amount after work. Reserved for a future metered tool. Not for current calculators or code search. - not offered `batch-settlement`: Not offered. Payment-channel vouchers claimed later in batches. Not the same as POST {items} bulk (that is still exact). Same-path POST {items} is still scheme exact: one EIP-3009 authorization for n times the GET unit. That is not x402 batch-settlement (payment channels / vouchers). ## 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.