# Shock index

Shock index

## Also searched as

- shock index
- Allgöwer shock index
- Burri shock index
- HR over SBP
- heart rate systolic ratio
- Allgower Burri index
- SI heart rate SBP

Status: LIVE
Price: $0.005 USDC
`GET /api/calc/shock_index`
HTML: https://magentlab.com/docs/shock-index
Markdown: https://magentlab.com/docs/shock-index.md

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

## What it computes

Compute the Allgöwer–Burri shock index as heart rate in bpm divided by cuff systolic pressure in mm Hg.

## When to use

When an agent needs the published heart-rate / systolic-pressure ratio and must not invent a shock cutoff or a MAP-based index.

## When not to use

- Not a diagnosis and not a treatment target. The original index is the ratio of heart rate to systolic pressure; magent does not diagnose shock.
- Does not apply a shock or no-shock cutoff.
- Does not use MAP or diastolic pressure in this tool.

## Formula

```
shock_index = heart_rate_bpm / systolic_mm_hg
```

## Citation

[Shock index](https://doi.org/10.1055/s-0028-1106070)
Allgöwer M, Burri C
Dtsch Med Wochenschr. 1967;92(43):1947-1950
DOI: [10.1055/s-0028-1106070](https://doi.org/10.1055/s-0028-1106070)

## Worked example

### HR 80, SBP 120

Given: `heart_rate_bpm=80, systolic_mm_hg=120`

1. shock_index = 80 / 120 = 0.666… → 0.67


### HR 120, SBP 80

Given: `heart_rate_bpm=120, systolic_mm_hg=80`

1. shock_index = 120 / 80 = 1.50


## Parameters

- `heart_rate_bpm` (integer, required): Heart rate in beats per minute (integer 30-220).
- `systolic_mm_hg` (number, required): Cuff systolic blood pressure in mm Hg (50-250).

## 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/shock_index`
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": [
    {
      "heart_rate_bpm": "80",
      "systolic_mm_hg": "120"
    },
    {
      "heart_rate_bpm": "80",
      "systolic_mm_hg": "120"
    }
  ]
}
```

Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/shock-index

Example 200:

```json
{
  "count": 2,
  "path": "/api/calc/shock_index",
  "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": "Allgöwer M, Burri C",
        "doi": "10.1055/s-0028-1106070",
        "id": "allgower-burri-1967",
        "source": "Dtsch Med Wochenschr. 1967;92(43):1947-1950",
        "title": "Shock index"
      },
      "formula": "shock_index",
      "formula_expression": "shock_index = heart_rate_bpm / systolic_mm_hg",
      "systolic_mm_hg": 120.0,
      "heart_rate_bpm": 80,
      "shock_index": 0.67
    },
    {
      "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": "Allgöwer M, Burri C",
        "doi": "10.1055/s-0028-1106070",
        "id": "allgower-burri-1967",
        "source": "Dtsch Med Wochenschr. 1967;92(43):1947-1950",
        "title": "Shock index"
      },
      "formula": "shock_index",
      "formula_expression": "shock_index = heart_rate_bpm / systolic_mm_hg",
      "systolic_mm_hg": 120.0,
      "heart_rate_bpm": 80,
      "shock_index": 0.67
    }
  ]
}
```

## Response fields

- `formula` (string): shock_index
- `formula_expression` (string): Exact expression used
- `heart_rate_bpm` (integer): Heart rate used, bpm
- `systolic_mm_hg` (number): Systolic pressure used, mm Hg
- `shock_index` (number): Heart rate divided by systolic pressure, 2 decimals
- `citation` (object): Allgöwer and Burri 1967 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": "Allgöwer M, Burri C",
    "doi": "10.1055/s-0028-1106070",
    "id": "allgower-burri-1967",
    "source": "Dtsch Med Wochenschr. 1967;92(43):1947-1950",
    "title": "Shock index"
  },
  "formula": "shock_index",
  "formula_expression": "shock_index = heart_rate_bpm / systolic_mm_hg",
  "systolic_mm_hg": 120.0,
  "heart_rate_bpm": 80,
  "shock_index": 0.67
}
```

## Errors

- HTTP 400 `invalid_heart_rate`: heart_rate_bpm must be an integer from 30 to 220 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.

Shared HTTP 402 and 503: https://magentlab.com/docs/payments

## Related tools

- [MAP](https://magentlab.com/docs/map) — Compute conventional estimated mean arterial pressure from cuff systolic and diastolic pressures.

## 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).

Shared HTTP 402 and 503 table: https://magentlab.com/docs/payments

Stdio MCP (one process per host): https://magentlab.com/docs/mcp

## 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.