# MESS Calculator (Mangled Extremity Severity Score)

> MESS Calculator (Mangled Extremity Severity Score) is a paid API for AI agents from api.magentlab.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-14).

Computes the Johansen 1990 Mangled Extremity Severity Score (MESS) from four caller-assigned inputs: skeletal/soft-tissue energy, limb ischemia, shock, and age, returning the total score and amputation-risk band.

## Facts

- Endpoint: GET https://api.magentlab.com/api/calc/mess
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/mess-calculator-mangled-extremity-severity-score-2916cae2
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_O7kwGi1A5ONViyaot2ero

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability mess-calculator-mangled-extremity-severity-score-2916cae2
```

Example prompt: Calculate the MESS score for a 45-year-old trauma patient with high-energy skeletal injury (score 3), pulseless limb with paresthesias (ischemia score 2), ischemia time of 8 hours, and transient hypotension (shock score 1).

## When to prefer this

Use this endpoint when you need fast, deterministic reproduction of the Johansen 1990 MESS formula for trauma documentation, clinical decision support audits, or EHR integration. Prefer it over manual calculation to eliminate arithmetic errors. Note: this implements the original 1990 cutoff of ≥7 (not later papers' cutoff of 8), and does not perform physical examination or make amputation recommendations.

## Known failure modes

- Invalid integer ranges for skeletal_soft_tissue (must be 1-4), limb_ischemia (must be 1-3), or shock (must be 0-2) return a validation error
- Age outside 0-120 integer range returns an error
- Missing required query parameters return a 400-level error
- ischemia_over_6h must be a boolean; non-boolean values cause a parse error
- Network errors or upstream downtime return 5xx responses

## How this service works

Johansen 1990 Mangled Extremity Severity Score (MESS): caller-assigned skeletal/soft-tissue energy 1-4, limb ischemia 1-3 (doubled if ischemia time >6 hours), shock 0-2, and age points (<30 → 0, 30-50 → 1, >50 → 2). Max 14. MESS ≥7 predicted amputation with 100% accuracy in that series (mess_band 0-6 or >=7). Deterministic published arithmetic with citation. Not an amputation or limb-salvage protocol; magent does not examine the limb. Not later papers' cutoff of 8.

## Output

Returns the numeric MESS total (integer 0–14), the risk band classification ('0-6' for below threshold or '>=7' for the Johansen 1990 amputation-predicted range), and the underlying component scores. This is deterministic published arithmetic with no clinical examination or limb-salvage recommendation.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "headers": {
     "type": "object",
     "additionalProperties": {
      "type": "string"
     }
    },
    "queryParams": {
     "type": "object",
     "required": [
      "skeletal_soft_tissue",
      "limb_ischemia",
      "shock",
      "age",
      "ischemia_over_6h"
     ],
     "properties": {
      "age": {
       "type": "integer",
       "description": "Age in years (integer 0-120). Johansen 1990 points: <30 → 0, 30-50 → 1, >50 → 2. Not the adult 18-120 clamp."
      },
      "shock": {
       "type": "integer",
       "description": "Caller-assigned Johansen 1990 shock (integer 0 SBP always >90, 1 transient <90, or 2 persistent <90)."
      },
      "limb_ischemia": {
       "type": "integer",
       "description": "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."
      },
      "ischemia_over_6h": {
       "type": "boolean",
       "description": "true if limb ischemia time is greater than 6 hours (Johansen 1990 doubles the ischemia score). true or false as assigned by the caller."
      },
      "skeletal_soft_tissue": {
       "type": "integer",
       "description": "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."
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "path": "/api/calc/mess",
  "count": 2,
  "items": [
   {
    "age": 25,
    "score": 2,
    "shock": 0,
    "formula": "mess",
    "citation": {
     "id": "johansen-1990",
     "doi": "10.1097/00005373-199005000-00007",
     "pmid": "2342140",
     "title": "Objective criteria accurately predict amputation following lower extremity trauma",
     "source": "J Trauma. 1990;30(5):568-572",
     "authors": "Johansen K, Daines M, Howey T, Helfet D, Hansen ST"
    },
    "max_score": 14,
    "mess_band": "0-6",
    "age_points": 0,
    "components": [
     {
      "value": 1,
      "factor": "skeletal_soft_tissue",
      "points": 1,
      "present": true
     },
     {
      "value": 1,
      "factor": "limb_ischemia",
      "points": 1,
      "doubled": false,
      "present": true
     },
     {
      "value": 0,
      "factor": "shock",
      "points": 0,
      "present": false
     },
     {
      "value": 25,
      "factor": "age",
      "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.",
    "limb_ischemia": 1,
    "ischemia_points": 1,
    "ischemia_over_6h": false,
    "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",
    "skeletal_soft_tissue": 1
   },
   {
    "age": 25,
    "score": 2,
    "shock": 0,
    "formula": "mess",
    "citation": {
     "id": "johansen-1990",
     "doi": "10.1097/00005373-199005000-00007",
     "pmid": "2342140",
     "title": "Objective criteria accurately predict amputation following lower extremity trauma",
     "source": "J Trauma. 1990;30(5):568-572",
     "authors": "Johansen K, Daines M, Howey T, Helfet D, Hansen ST"
    },
    "max_score": 14,
    "mess_band": "0-6",
    "age_points": 0,
    "components": [
     {
      "value": 1,
      "factor": "skeletal_soft_tissue",
      "points": 1,
      "present": true
     },
     {
      "value": 1,
      "factor": "limb_ischemia",
      "points": 1,
      "doubled": false,
      "present": true
     },
     {
      "value": 0,
      "factor": "shock",
      "points": 0,
      "present": false
     },
     {
      "value": 25,
      "factor": "age",
      "points": 0,
      "present"
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/mess-calculator-mangled-extremity-severity-score-2916cae2/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.magentlab.com](https://www.zero.xyz/host/api.magentlab.com/llms.txt)