# Pulmonary artery pulsatility index

PAPi

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

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

## What it computes

Compute Korabathina 2012 pulmonary artery pulsatility index from PA systolic, PA diastolic, and right atrial pressure.

## When to use

When an agent needs the published Korabathina 2012 PAPi ((PA systolic − PA diastolic) / RAP) and must not invent an RAP=0 substitution, a device threshold, or a diagnosis of RV failure.

## When not to use

- Not a medical device. Not a diagnosis of right ventricular failure.
- 0.9 is the Korabathina 2012 ROC cut-point for in-hospital death or need for percutaneous RV support in inferior MI with suspected RVD, not a device threshold and not an RVAD/Impella indication.
- RAP 0 is invalid. Korabathina 2012 did not substitute RAP=1.
- Inputs are invasive catheter numbers. magent does not read waveforms.

## Formula

```
papi = (pa_systolic_mm_hg - pa_diastolic_mm_hg) / ra_mm_hg
```

## Citation

[The pulmonary artery pulsatility index identifies severe right ventricular dysfunction in acute inferior myocardial infarction.](https://doi.org/10.1002/ccd.23309)
Korabathina R, Heffernan KS, Paruchuri V, et al.
Catheter Cardiovasc Interv. 2012;80(4):593-600
DOI: [10.1002/ccd.23309](https://doi.org/10.1002/ccd.23309)

## Worked example

### PAS 30, PAD 12, RAP 6

Given: `pa_diastolic_mm_hg=12, pa_systolic_mm_hg=30, ra_mm_hg=6`

1. papi = (30 − 12) / 6 = 3.0 → 3.00
2. unrounded 3.0 > 0.9 → band >0.9


## Also searched as

- pulmonary artery pulsatility index
- PAPi
- PAPI
- PA pulsatility index
- Korabathina PAPi
- right ventricular pulsatility
- PA pulse pressure RAP

## Parameters

- `pa_systolic_mm_hg` (number, required): Pulmonary artery systolic pressure in mm Hg (10-150). Invasive catheter number; this tool does not read waveforms.
- `pa_diastolic_mm_hg` (number, required): Pulmonary artery diastolic pressure in mm Hg (1-80). Must be less than PA systolic.
- `ra_mm_hg` (number, required): Right atrial pressure in mm Hg (1-40). RAP 0 is invalid; Korabathina 2012 did not substitute RAP=1.

## 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/papi`
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": [
    {
      "pa_diastolic_mm_hg": "12",
      "pa_systolic_mm_hg": "30",
      "ra_mm_hg": "6"
    },
    {
      "pa_diastolic_mm_hg": "12",
      "pa_systolic_mm_hg": "30",
      "ra_mm_hg": "6"
    }
  ]
}
```

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

Example 200:

```json
{
  "count": 2,
  "path": "/api/calc/papi",
  "items": [
    {
      "band": ">0.9",
      "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": "Korabathina R, Heffernan KS, Paruchuri V, et al.",
        "doi": "10.1002/ccd.23309",
        "id": "korabathina-2012",
        "pmid": "21954053",
        "source": "Catheter Cardiovasc Interv. 2012;80(4):593-600",
        "title": "The pulmonary artery pulsatility index identifies severe right ventricular dysfunction in acute inferior myocardial infarction."
      },
      "formula": "papi",
      "formula_expression": "papi = (pa_systolic_mm_hg - pa_diastolic_mm_hg) / ra_mm_hg",
      "pa_diastolic_mm_hg": 12.0,
      "pa_systolic_mm_hg": 30.0,
      "papi": 3.0,
      "ra_mm_hg": 6.0
    },
    {
      "band": ">0.9",
      "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": "Korabathina R, Heffernan KS, Paruchuri V, et al.",
        "doi": "10.1002/ccd.23309",
        "id": "korabathina-2012",
        "pmid": "21954053",
        "source": "Catheter Cardiovasc Interv. 2012;80(4):593-600",
        "title": "The pulmonary artery pulsatility index identifies severe right ventricular dysfunction in acute inferior myocardial infarction."
      },
      "formula": "papi",
      "formula_expression": "papi = (pa_systolic_mm_hg - pa_diastolic_mm_hg) / ra_mm_hg",
      "pa_diastolic_mm_hg": 12.0,
      "pa_systolic_mm_hg": 30.0,
      "papi": 3.0,
      "ra_mm_hg": 6.0
    }
  ]
}
```

## Response fields

- `formula` (string): papi
- `formula_expression` (string): Exact expression used
- `pa_systolic_mm_hg` (number): Pulmonary artery systolic pressure used, mm Hg
- `pa_diastolic_mm_hg` (number): Pulmonary artery diastolic pressure used, mm Hg
- `ra_mm_hg` (number): Right atrial pressure used, mm Hg
- `papi` (number): Pulmonary artery pulsatility index, 2 decimals
- `band` (string): Korabathina 2012 ROC cut-point from the unrounded PAPi: <=0.9 or >0.9. Equality at 0.9 is <=0.9.
- `citation` (object): Korabathina 2012 PAPi citation
- `disclaimer` (string): Not-a-device notice

## Example JSON

Frozen fixture. Not a live lookup.

```json
{
  "band": ">0.9",
  "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": "Korabathina R, Heffernan KS, Paruchuri V, et al.",
    "doi": "10.1002/ccd.23309",
    "id": "korabathina-2012",
    "pmid": "21954053",
    "source": "Catheter Cardiovasc Interv. 2012;80(4):593-600",
    "title": "The pulmonary artery pulsatility index identifies severe right ventricular dysfunction in acute inferior myocardial infarction."
  },
  "formula": "papi",
  "formula_expression": "papi = (pa_systolic_mm_hg - pa_diastolic_mm_hg) / ra_mm_hg",
  "pa_diastolic_mm_hg": 12.0,
  "pa_systolic_mm_hg": 30.0,
  "papi": 3.0,
  "ra_mm_hg": 6.0
}
```

## Errors

- HTTP 400 `invalid_pa_systolic`: pa_systolic_mm_hg must be a number from 10 to 150 (Korabathina 2012 PAPi). Returned before settlement; you are not charged.
- HTTP 400 `invalid_pa_diastolic`: pa_diastolic_mm_hg must be a number from 1 to 80 (Korabathina 2012 PAPi). Returned before settlement; you are not charged.
- HTTP 400 `invalid_ra_pressure`: ra_mm_hg must be a number from 1 to 40 (Korabathina 2012 PAPi; RAP 0 is not scored). Returned before settlement; you are not charged.
- HTTP 400 `invalid_pa_pulse_pressure`: pa_diastolic_mm_hg must be less than pa_systolic_mm_hg (Korabathina 2012 PAPi). 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

- [CPO](https://magentlab.com/docs/cpo) — Compute Fincke 2004 cardiac power output in watts from mean arterial pressure and cardiac output.
- [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.

## 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 echoing accepted, payload, and extensions when present).
- 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.