Emergency · LIVE

MESS

Compute the Johansen 1990 Mangled Extremity Severity Score from caller-assigned skeletal/soft-tissue, limb ischemia, shock, and age integers, doubling ischemia when time exceeds 6 hours, and return the published 0-6 / ≥7 band.

LIVE $0.005 USDC GET /api/calc/mess

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

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

What it computes

When to use

When an agent has already assigned Johansen 1990 MESS category integers and needs the published total and ≥7 band, not an amputation or limb-salvage decision.

When not to use

Not a medical device and not an amputation, revascularization, or limb-salvage decision or protocol.
Category integers are caller-assigned. magent does not examine the limb, pulses, perfusion, or blood pressure.
This is Johansen 1990 MESS only. MESS ≥7 predicted amputation with 100% accuracy in that series. It does not use later papers' cutoff of 8.

Formula

MESS = skeletal_soft_tissue (1-4) + limb_ischemia (1-3, doubled if ischemia_over_6h) + shock (0-2) + age_points (<30 → 0, 30-50 → 1, >50 → 2); Johansen 1990 band 0-6 / >=7; max 14

Citation

Title: Objective criteria accurately predict amputation following lower extremity trauma
Authors: Johansen K, Daines M, Howey T, Helfet D, Hansen ST
Source: J Trauma. 1990;30(5):568-572
DOI: 10.1097/00005373-199005000-00007

Worked example

Low-energy limb, young adult, no shock

Given: age=25ischemia_over_6h=falselimb_ischemia=1shock=0skeletal_soft_tissue=1

skeletal_soft_tissue 1 + limb_ischemia 1 (not doubled) + shock 0 + age 25 → 0
Score = 2 (max 14); mess_band 0-6

Very high energy and grade-3 ischemia, not doubled

Given: age=25ischemia_over_6h=falselimb_ischemia=3shock=0skeletal_soft_tissue=4

skeletal_soft_tissue 4 + limb_ischemia 3 (not doubled) + shock 0 + age 25 → 0
Score = 7 (max 14); mess_band >=7

Also searched as

MESS
mangled extremity severity score
Johansen MESS
mangled extremity score
MESS trauma
limb ischemia MESS
MESS ≥7

Try

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

/api/calc/mess?skeletal_soft_tissue=1&limb_ischemia=1&shock=0&age=25&ischemia_over_6h=false

Full URL: https://api.magentlab.com/api/calc/mess?skeletal_soft_tissue=1&limb_ischemia=1&shock=0&age=25&ischemia_over_6h=false

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/mess?skeletal_soft_tissue=1&limb_ischemia=1&shock=0&age=25&ischemia_over_6h=false"

Parameters

Name	Type	Required	Description
`skeletal_soft_tissue`	integer	required	Caller-assigned Johansen 1990 skeletal/soft-tissue energy (integer 1 low, 2 medium, 3 high, or 4 very high). magent does not examine the limb.
`limb_ischemia`	integer	required	Caller-assigned Johansen 1990 limb ischemia (integer 1 pulse reduced but perfusion normal, 2 pulseless with paresthesia, or 3 cool paralyzed insensate). Doubled when ischemia_over_6h is true.
`shock`	integer	required	Caller-assigned Johansen 1990 shock (integer 0 SBP always >90, 1 transient <90, or 2 persistent <90).
`age`	integer	required	Age in years (integer 0-120). Johansen 1990 points: <30 → 0, 30-50 → 1, >50 → 2. Not the adult 18-120 clamp.
`ischemia_over_6h`	boolean	required	true if limb ischemia time is greater than 6 hours (Johansen 1990 doubles the ischemia score). true or false as assigned by the caller.

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.

POST /api/calc/mess Max 25 unit_amount + extra_item_amount * (n - 1) extra $0.002 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 (fixture)

{
  "items": [
    {
      "age": "25",
      "ischemia_over_6h": "false",
      "limb_ischemia": "1",
      "shock": "0",
      "skeletal_soft_tissue": "1"
    },
    {
      "age": "25",
      "ischemia_over_6h": "false",
      "limb_ischemia": "1",
      "shock": "0",
      "skeletal_soft_tissue": "1"
    }
  ]
}

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/mess",
  "items": [
    {
      "components": [
        {
          "value": 1,
          "factor": "skeletal_soft_tissue",
          "points": 1,
          "present": true
        },
        {
          "value": 1,
          "factor": "limb_ischemia",
          "points": 1,
          "present": true,
          "doubled": false
        },
        {
          "value": 0,
          "factor": "shock",
          "points": 0,
          "present": false
        },
        {
          "value": 25,
          "factor": "age",
          "points": 0,
          "present": false
        }
      ],
      "age": 25,
      "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": "Johansen K, Daines M, Howey T, Helfet D, Hansen ST",
        "doi": "10.1097/00005373-199005000-00007",
        "id": "johansen-1990",
        "pmid": "2342140",
        "source": "J Trauma. 1990;30(5):568-572",
        "title": "Objective criteria accurately predict amputation following lower extremity trauma"
      },
      "formula": "mess",
      "formula_expression": "MESS = skeletal_soft_tissue (1-4) + limb_ischemia (1-3, doubled if ischemia_over_6h) + shock (0-2) + age_points (<30 → 0, 30-50 → 1, >50 → 2); Johansen 1990 band 0-6 / >=7; max 14",
      "max_score": 14,
      "score": 2,
      "age_points": 0,
      "ischemia_over_6h": false,
      "ischemia_points": 1,
      "limb_ischemia": 1,
      "mess_band": "0-6",
      "shock": 0,
      "skeletal_soft_tissue": 1
    },
    {
      "components": [
        {
          "value": 1,
          "factor": "skeletal_soft_tissue",
          "points": 1,
          "present": true
        },
        {
          "value": 1,
          "factor": "limb_ischemia",
          "points": 1,
          "present": true,
          "doubled": false
        },
        {
          "value": 0,
          "factor": "shock",
          "points": 0,
          "present": false
        },
        {
          "value": 25,
          "factor": "age",
          "points": 0,
          "present": false
        }
      ],
      "age": 25,
      "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": "Johansen K, Daines M, Howey T, Helfet D, Hansen ST",
        "doi": "10.1097/00005373-199005000-00007",
        "id": "johansen-1990",
        "pmid": "2342140",
        "source": "J Trauma. 1990;30(5):568-572",
        "title": "Objective criteria accurately predict amputation following lower extremity trauma"
      },
      "formula": "mess",
      "formula_expression": "MESS = skeletal_soft_tissue (1-4) + limb_ischemia (1-3, doubled if ischemia_over_6h) + shock (0-2) + age_points (<30 → 0, 30-50 → 1, >50 → 2); Johansen 1990 band 0-6 / >=7; max 14",
      "max_score": 14,
      "score": 2,
      "age_points": 0,
      "ischemia_over_6h": false,
      "ischemia_points": 1,
      "limb_ischemia": 1,
      "mess_band": "0-6",
      "shock": 0,
      "skeletal_soft_tissue": 1
    }
  ]
}

Response

Field	Type	Description
`formula`	string	mess
`formula_expression`	string	Exact expression used
`score`	integer	MESS points 2-14
`max_score`	integer	14
`mess_band`	string	Johansen 1990 band: 0-6 or >=7. MESS ≥7 predicted amputation with 100% accuracy in that series. Not an amputation order.
`skeletal_soft_tissue`	integer	Caller-assigned skeletal/soft-tissue energy 1-4
`limb_ischemia`	integer	Caller-assigned limb ischemia 1-3
`shock`	integer	Caller-assigned shock 0-2
`age`	integer	Caller age in years 0-120
`age_points`	integer	Johansen 1990 age points 0, 1, or 2
`ischemia_over_6h`	boolean	Whether the published >6 hour ischemia doubling was applied
`ischemia_points`	integer	Limb ischemia points after the optional >6 hour doubling (1-6)
`components`	array	Per-factor points
`citation`	object	Johansen et al. J Trauma 1990 citation
`disclaimer`	string	Not-a-device notice

Example JSON

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

{
  "components": [
    {
      "value": 1,
      "factor": "skeletal_soft_tissue",
      "points": 1,
      "present": true
    },
    {
      "value": 1,
      "factor": "limb_ischemia",
      "points": 1,
      "present": true,
      "doubled": false
    },
    {
      "value": 0,
      "factor": "shock",
      "points": 0,
      "present": false
    },
    {
      "value": 25,
      "factor": "age",
      "points": 0,
      "present": false
    }
  ],
  "age": 25,
  "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": "Johansen K, Daines M, Howey T, Helfet D, Hansen ST",
    "doi": "10.1097/00005373-199005000-00007",
    "id": "johansen-1990",
    "pmid": "2342140",
    "source": "J Trauma. 1990;30(5):568-572",
    "title": "Objective criteria accurately predict amputation following lower extremity trauma"
  },
  "formula": "mess",
  "formula_expression": "MESS = skeletal_soft_tissue (1-4) + limb_ischemia (1-3, doubled if ischemia_over_6h) + shock (0-2) + age_points (<30 → 0, 30-50 → 1, >50 → 2); Johansen 1990 band 0-6 / >=7; max 14",
  "max_score": 14,
  "score": 2,
  "age_points": 0,
  "ischemia_over_6h": false,
  "ischemia_points": 1,
  "limb_ischemia": 1,
  "mess_band": "0-6",
  "shock": 0,
  "skeletal_soft_tissue": 1
}

Client errors (HTTP 400)

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

HTTP	Code	When
400	`invalid_mess_item`	skeletal_soft_tissue 1-4, limb_ischemia 1-3, and shock 0-2 (Johansen 1990). Returned before settlement; you are not charged.
400	`invalid_mess_age`	age must be an integer from 0 to 120 (Johansen 1990 includes children). Returned before settlement; you are not charged.
400	`invalid_flag`	boolean clinical flags must be true or false Returned before settlement; you are not charged.
400	`invalid_items`	POST body must be a JSON object with only an items array Returned before settlement; you are not charged.
400	`invalid_item_count`	items must be an array of 1 to 25 objects Returned before settlement; you are not charged.
400	`invalid_item`	each items entry must be a JSON object Returned before settlement; you are not charged.

Related tools

ISS — Compute the Baker 1974 Injury Severity Score as the sum of squares of the three highest caller-assigned AIS body-region grades, or 75 if any region is AIS 6.
RTS — Compute Champion 1989 coded GCS, SBP, and respiratory-rate values, the triage T-RTS sum, and the weighted RTS used for outcome evaluation.
ABC score — Sum the four Nunez 2009 ABC (assessment of blood consumption) arrival factors and return score_ge_2 at the published ≥2 cutoff.

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. 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

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.