# NEXUS Chest NEXUS Chest Status: LIVE Price: $0.005 USDC `GET /api/calc/nexus_chest` HTML: https://magentlab.com/docs/nexus-chest Markdown: https://magentlab.com/docs/nexus-chest.md Not a medical device. Not a diagnosis, dose, or listing recommendation. ## What it computes Apply the Rodriguez 2011 NEXUS Chest decision instrument and return whether the seven low-risk criteria all hold (chest radiography not indicated by this instrument). ## When to use When an agent has caller-assigned findings after blunt trauma and needs the published NEXUS Chest selective chest-radiography instrument, not the Hoffman 2000 NEXUS C-spine rule. ## When not to use - Not a diagnosis. magent does not examine the patient or the chest. - This tool is the Rodriguez 2011 NEXUS Chest decision instrument for selective chest radiography only. It is not the Hoffman 2000 NEXUS C-spine rule and not a NEXUS Chest CT instrument. - Derivation enrolled blunt trauma age >14. magent does not take numeric age; the caller assigns age >60 as one of the seven criteria. - The caller assigns all seven criteria. Does not replace imaging when any criterion fails. ## Formula ``` NEXUS Chest low-risk iff no chest pain and no distracting injury and no chest-wall tenderness and no intoxication and age not >60 and no rapid deceleration and no altered mental status ``` ## Citation [Derivation of a decision instrument for selective chest radiography in blunt trauma](https://doi.org/10.1097/TA.0b013e3181f2ac9d) Rodriguez RM, Hendey GW, Mower W, et al. J Trauma. 2011;71(3):549-553 DOI: [10.1097/TA.0b013e3181f2ac9d](https://doi.org/10.1097/TA.0b013e3181f2ac9d) ## Worked example ### All seven low-risk criteria hold Given: `age_gt_60=false, altered_mental_status=false, chest_pain=false, chest_wall_tenderness=false, distracting_injury=false, intoxication=false, rapid_deceleration=false` 1. No chest pain, no distracting injury, no chest-wall tenderness, no intoxication, age not >60, no rapid deceleration, no altered mental status 2. NEXUS Chest low-risk; chest radiography is not indicated by this instrument ### Chest pain alone fails the instrument Given: `age_gt_60=false, altered_mental_status=false, chest_pain=true, chest_wall_tenderness=false, distracting_injury=false, intoxication=false, rapid_deceleration=false` 1. Chest pain is present 2. The low-risk criterion fails; chest radiography is indicated by this instrument ## Also searched as - NEXUS Chest - NEXUS Chest radiography - Rodriguez NEXUS Chest - selective chest radiography - blunt trauma chest x-ray rule - NEXUS Chest decision instrument - NEXUS Chest seven criteria ## Parameters - `chest_pain` (boolean, required): Chest pain. true means chest pain is present and the low-risk criterion fails. true or false as assigned by the caller. magent does not examine the patient. - `distracting_injury` (boolean, required): Painful, distracting injury. true means a distracting injury is present and the low-risk criterion fails. true or false as assigned by the caller. - `chest_wall_tenderness` (boolean, required): Tenderness to chest-wall palpation. true means tenderness is present and the low-risk criterion fails. true or false as assigned by the caller. magent does not palpate the chest. - `intoxication` (boolean, required): Intoxication. true means intoxicated and the low-risk criterion fails. true or false as assigned by the caller. - `age_gt_60` (boolean, required): Age greater than 60 years as assigned by the caller (a NEXUS Chest criterion, not a numeric age input). true means age >60 and the low-risk criterion fails. true or false. magent does not take numeric age. - `rapid_deceleration` (boolean, required): Rapid deceleration mechanism (paper: fall from >20 feet or motor vehicle crash >40 mph) as assigned by the caller. true means the mechanism is present and the low-risk criterion fails. true or false. magent does not classify mechanism. - `altered_mental_status` (boolean, required): Altered alertness or mental status. true means altered mental status is present and the low-risk criterion fails. true or false as assigned by the caller. magent does not examine the patient. ## Bulk (POST) POST the same path with a JSON items array. The first item is the GET unit; each additional item is $0.002. Invalid items return HTTP 400 before settlement. Method: `POST /api/calc/nexus_chest` Max items: 25 Price: unit_amount + extra_item_amount * (n - 1) (unit 5000 atomic, extra 2000 atomic) Status: PREVIEW - 1 to 25 items. Each item uses the same keys as the GET query parameters. - POST of 1 item costs the same as GET. Lists longer than 25: chunk into multiple POSTs. Extra items still execute; do not pad dummy rows. - 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": [ { "age_gt_60": "false", "altered_mental_status": "false", "chest_pain": "false", "chest_wall_tenderness": "false", "distracting_injury": "false", "intoxication": "false", "rapid_deceleration": "false" }, { "age_gt_60": "false", "altered_mental_status": "false", "chest_pain": "false", "chest_wall_tenderness": "false", "distracting_injury": "false", "intoxication": "false", "rapid_deceleration": "false" } ] } ``` Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/nexus-chest Example 200: ```json { "count": 2, "path": "/api/calc/nexus_chest", "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": "Rodriguez RM, Hendey GW, Mower W, et al.", "doi": "10.1097/TA.0b013e3181f2ac9d", "id": "rodriguez-2011", "pmid": "21045745", "source": "J Trauma. 2011;71(3):549-553", "title": "Derivation of a decision instrument for selective chest radiography in blunt trauma" }, "formula": "nexus_chest", "formula_expression": "NEXUS Chest low-risk iff no chest pain and no distracting injury and no chest-wall tenderness and no intoxication and age not >60 and no rapid deceleration and no altered mental status", "criteria": [ { "factor": "no_chest_pain", "met": true }, { "factor": "no_distracting_injury", "met": true }, { "factor": "no_chest_wall_tenderness", "met": true }, { "factor": "no_intoxication", "met": true }, { "factor": "no_age_gt_60", "met": true }, { "factor": "no_rapid_deceleration", "met": true }, { "factor": "no_altered_mental_status", "met": true } ], "chest_xray_indicated": false, "nexus_chest_low_risk": true }, { "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": "Rodriguez RM, Hendey GW, Mower W, et al.", "doi": "10.1097/TA.0b013e3181f2ac9d", "id": "rodriguez-2011", "pmid": "21045745", "source": "J Trauma. 2011;71(3):549-553", "title": "Derivation of a decision instrument for selective chest radiography in blunt trauma" }, "formula": "nexus_chest", "formula_expression": "NEXUS Chest low-risk iff no chest pain and no distracting injury and no chest-wall tenderness and no intoxication and age not >60 and no rapid deceleration and no altered mental status", "criteria": [ { "factor": "no_chest_pain", "met": true }, { "factor": "no_distracting_injury", "met": true }, { "factor": "no_chest_wall_tenderness", "met": true }, { "factor": "no_intoxication", "met": true }, { "factor": "no_age_gt_60", "met": true }, { "factor": "no_rapid_deceleration", "met": true }, { "factor": "no_altered_mental_status", "met": true } ], "chest_xray_indicated": false, "nexus_chest_low_risk": true } ] } ``` ## Response fields - `formula` (string): nexus_chest - `formula_expression` (string): Rodriguez 2011 seven low-risk criteria - `nexus_chest_low_risk` (boolean): true only when all seven low-risk criteria hold. Chest radiography is not indicated by this instrument when true. Not a diagnosis. - `chest_xray_indicated` (boolean): true when nexus_chest_low_risk is false. Not a diagnosis of thoracic injury. - `criteria` (array): Per-factor rows with factor and met; met is true when that NEXUS Chest low-risk item holds (the finding is absent) - `citation` (object): Rodriguez 2011 J Trauma citation - `disclaimer` (string): Not-a-device notice ## Example JSON Frozen fixture. Not a live lookup. ```json { "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": "Rodriguez RM, Hendey GW, Mower W, et al.", "doi": "10.1097/TA.0b013e3181f2ac9d", "id": "rodriguez-2011", "pmid": "21045745", "source": "J Trauma. 2011;71(3):549-553", "title": "Derivation of a decision instrument for selective chest radiography in blunt trauma" }, "formula": "nexus_chest", "formula_expression": "NEXUS Chest low-risk iff no chest pain and no distracting injury and no chest-wall tenderness and no intoxication and age not >60 and no rapid deceleration and no altered mental status", "criteria": [ { "factor": "no_chest_pain", "met": true }, { "factor": "no_distracting_injury", "met": true }, { "factor": "no_chest_wall_tenderness", "met": true }, { "factor": "no_intoxication", "met": true }, { "factor": "no_age_gt_60", "met": true }, { "factor": "no_rapid_deceleration", "met": true }, { "factor": "no_altered_mental_status", "met": true } ], "chest_xray_indicated": false, "nexus_chest_low_risk": true } ``` ## Errors - HTTP 400 `invalid_flag`: boolean clinical flags must be true or false 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. Shared HTTP 402 and 503: https://magentlab.com/docs/payments ## Related tools - [NEXUS C-spine](https://magentlab.com/docs/nexus) — Apply the Hoffman 2000 NEXUS C-spine rule and return whether the five low-risk criteria all hold (imaging not indicated by this rule). - [Canadian C-spine rule](https://magentlab.com/docs/canadian-c-spine) — Apply the Stiell 2001 Canadian C-spine rule and return whether cervical radiography is indicated from caller-assigned age, high-risk factors, low-risk factors, and neck rotation. ## Payment Unpaid requests return HTTP 402 even if query parameters or POST items are missing or invalid, so CDP and agents can index the path. After a PAYMENT-SIGNATURE, 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 accepts[0] (exact, EIP-3009) with validBefore = now + maxTimeoutSeconds (600 seconds), or accepts[1] (batch-settlement deposit/voucher) on product GET. Ping and POST {items} stay exact. Magent retries transient facilitator 429/5xx before answering. - Retry the same URL with PAYMENT-SIGNATURE (base64 JSON of accepted and payload). Magent attaches canonical extensions.bazaar on CDP verify/settle; echoing 402 bazaar is optional. - Success is HTTP 200 JSON plus PAYMENT-RESPONSE. exact settles before the tool. batch-settlement verifies (and deposit-settles) before the tool and commits the charge after HTTP 2xx. HTTP 503: retry the same PAYMENT-SIGNATURE. Mint a new exact 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. - offered `batch-settlement` on eip155:8453: Payment-channel vouchers claimed later in batches. Exact stays accepts[0]. Same-path POST {items} is still exact. extra.assetTransferMethod=eip3009 extra.paymentFlow=authorization. - 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. Same-path POST {items} is still scheme exact: one EIP-3009 authorization for GET unit plus $0.002 per extra item. That is not x402 batch-settlement (payment channels / vouchers). Shared HTTP 402 and 503 table: https://magentlab.com/docs/payments Stdio MCP (one process per host): https://magentlab.com/docs/mcp ## Guarantees - HTTP 402 is unpaid, including a missing query. After PAYMENT-SIGNATURE, invalid parameters return HTTP 400 before settlement. You are not charged. - exact: settlement finishes before the tool (paymentFlow upfront). batch-settlement: verify/deposit before the tool; chargedCumulativeAmount commits after HTTP 2xx. 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.