# SIPA (pediatric age-adjusted shock index)

SIPA

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

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

## What it computes

Compute Acker 2015 SIPA as heart rate in bpm divided by cuff systolic pressure in mm Hg, then compare the ratio with the published age-band cutoff.

## When to use

When an agent has caller-assigned age (4-16 years), heart rate, and systolic pressure and needs the published pediatric age-adjusted shock-index ratio and elevated flag.

## When not to use

- Not a diagnosis of shock and not a medical device. magent does not measure heart rate or blood pressure; the caller assigns the numbers.
- Not the adult shock-index cutoff of greater than 0.9. Acker 2015 SIPA uses age-adjusted cutoffs: greater than 1.22 (ages 4-6), greater than 1.0 (ages 7-12), and greater than 0.9 (ages 13-16).
- Do not apply SIPA to infants or to adults 17 years and older. The published cohort is ages 4-16 inclusive.

## Formula

```
sipa = heart_rate_bpm / systolic_mm_hg; elevated iff sipa > cutoff (Acker 2015: age 4-6 → 1.22, 7-12 → 1.0, 13-16 → 0.9)
```

## Citation

[Pediatric specific shock index accurately identifies severely injured children](https://doi.org/10.1016/j.jpedsurg.2014.08.009)
Acker SN, Ross JT, Partrick DA, Tong S, Bensard DD
J Pediatr Surg. 2015;50(2):331-334
DOI: [10.1016/j.jpedsurg.2014.08.009](https://doi.org/10.1016/j.jpedsurg.2014.08.009)

## Worked example

### Age 10, HR 80, SBP 100

Given: `age=10, heart_rate_bpm=80, systolic_mm_hg=100`

1. sipa = 80 / 100 = 0.80
2. Age 10 is in 7-12 → cutoff 1.0
3. 0.80 is not > 1.0 → elevated false


### Age 5, HR 123, SBP 100

Given: `age=5, heart_rate_bpm=123, systolic_mm_hg=100`

1. sipa = 123 / 100 = 1.23
2. Age 5 is in 4-6 → cutoff 1.22
3. 1.23 > 1.22 → elevated true


## Also searched as

- SIPA
- pediatric shock index
- shock index pediatric age-adjusted
- Acker SIPA
- age-adjusted shock index
- pediatric SI
- HR over SBP children
- pediatric age-adjusted SI

## Parameters

- `age` (integer, required): Age in years (integer 4-16). Acker 2015 SIPA cohort only. Ages 4-6 use cutoff 1.22, 7-12 use 1.0, and 13-16 use 0.9. Not for infants or adults 17 and older.
- `heart_rate_bpm` (integer, required): Heart rate in beats per minute (integer 30-220). magent does not measure vitals; the caller assigns the number.
- `systolic_mm_hg` (number, required): Cuff systolic blood pressure in mm Hg (50-250). magent does not measure vitals.

## 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/sipa`
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": "10",
      "heart_rate_bpm": "80",
      "systolic_mm_hg": "100"
    },
    {
      "age": "10",
      "heart_rate_bpm": "80",
      "systolic_mm_hg": "100"
    }
  ]
}
```

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

Example 200:

```json
{
  "count": 2,
  "path": "/api/calc/sipa",
  "items": [
    {
      "age": 10,
      "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": "Acker SN, Ross JT, Partrick DA, Tong S, Bensard DD",
        "doi": "10.1016/j.jpedsurg.2014.08.009",
        "id": "acker-2015",
        "pmid": "25638631",
        "source": "J Pediatr Surg. 2015;50(2):331-334",
        "title": "Pediatric specific shock index accurately identifies severely injured children"
      },
      "formula": "sipa",
      "formula_expression": "sipa = heart_rate_bpm / systolic_mm_hg; elevated iff sipa > cutoff (Acker 2015: age 4-6 → 1.22, 7-12 → 1.0, 13-16 → 0.9)",
      "systolic_mm_hg": 100.0,
      "criteria": [
        {
          "value": 1.22,
          "factor": "age_4_6",
          "met": false
        },
        {
          "value": 1.0,
          "factor": "age_7_12",
          "met": true
        },
        {
          "value": 0.9,
          "factor": "age_13_16",
          "met": false
        }
      ],
      "heart_rate_bpm": 80,
      "cutoff": 1.0,
      "elevated": false,
      "sipa": 0.8
    },
    {
      "age": 10,
      "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": "Acker SN, Ross JT, Partrick DA, Tong S, Bensard DD",
        "doi": "10.1016/j.jpedsurg.2014.08.009",
        "id": "acker-2015",
        "pmid": "25638631",
        "source": "J Pediatr Surg. 2015;50(2):331-334",
        "title": "Pediatric specific shock index accurately identifies severely injured children"
      },
      "formula": "sipa",
      "formula_expression": "sipa = heart_rate_bpm / systolic_mm_hg; elevated iff sipa > cutoff (Acker 2015: age 4-6 → 1.22, 7-12 → 1.0, 13-16 → 0.9)",
      "systolic_mm_hg": 100.0,
      "criteria": [
        {
          "value": 1.22,
          "factor": "age_4_6",
          "met": false
        },
        {
          "value": 1.0,
          "factor": "age_7_12",
          "met": true
        },
        {
          "value": 0.9,
          "factor": "age_13_16",
          "met": false
        }
      ],
      "heart_rate_bpm": 80,
      "cutoff": 1.0,
      "elevated": false,
      "sipa": 0.8
    }
  ]
}
```

## Response fields

- `formula` (string): sipa
- `formula_expression` (string): Exact expression used
- `age` (integer): Age in years used (4-16)
- `heart_rate_bpm` (integer): Heart rate used, bpm
- `systolic_mm_hg` (number): Systolic pressure used, mm Hg
- `sipa` (number): Heart rate divided by systolic pressure, 2 decimals
- `cutoff` (number): Acker 2015 age-band cutoff: 1.22 (ages 4-6), 1.0 (7-12), or 0.9 (13-16)
- `elevated` (boolean): true only when sipa is strictly greater than the age-band cutoff
- `criteria` (array): age_4_6, age_7_12, and age_13_16 rows with factor, met, and cutoff value
- `citation` (object): Acker 2015 citation
- `disclaimer` (string): Not-a-device notice

## Example JSON

Frozen fixture. Not a live lookup.

```json
{
  "age": 10,
  "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": "Acker SN, Ross JT, Partrick DA, Tong S, Bensard DD",
    "doi": "10.1016/j.jpedsurg.2014.08.009",
    "id": "acker-2015",
    "pmid": "25638631",
    "source": "J Pediatr Surg. 2015;50(2):331-334",
    "title": "Pediatric specific shock index accurately identifies severely injured children"
  },
  "formula": "sipa",
  "formula_expression": "sipa = heart_rate_bpm / systolic_mm_hg; elevated iff sipa > cutoff (Acker 2015: age 4-6 → 1.22, 7-12 → 1.0, 13-16 → 0.9)",
  "systolic_mm_hg": 100.0,
  "criteria": [
    {
      "value": 1.22,
      "factor": "age_4_6",
      "met": false
    },
    {
      "value": 1.0,
      "factor": "age_7_12",
      "met": true
    },
    {
      "value": 0.9,
      "factor": "age_13_16",
      "met": false
    }
  ],
  "heart_rate_bpm": 80,
  "cutoff": 1.0,
  "elevated": false,
  "sipa": 0.8
}
```

## Errors

- HTTP 400 `invalid_sipa_age`: age must be an integer from 4 to 16 (Acker 2015 SIPA cohort). Returned before settlement; you are not charged.
- 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

- [Shock index](https://magentlab.com/docs/shock-index) — Compute the Allgöwer–Burri shock index as heart rate in bpm divided by cuff systolic pressure in mm Hg.
- [PECARN pediatric IAI](https://magentlab.com/docs/pecarn-iai) — Apply the Holmes 2013 PECARN seven-variable prediction rule and return whether the child is at very low risk of intra-abdominal injury requiring acute intervention (all seven caller-assigned findings absent). Does not order a CT.

## 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. HTTP 402 never includes the tool JSON.
- 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.