# BPS (Payen)

BPS

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

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

## What it computes

Sum three caller-assigned Payen 2001 BPS integers (1-4) and return the published total (range 3-12).

## When to use

When an agent has already assigned Payen 2001 1-4 integers for facial expression, upper limbs, and compliance with ventilation and needs the published total, not a pain diagnosis, analgesic order, or later pain-present cutoff.

## When not to use

- Not a medical device and not a pain diagnosis or analgesic order.
- Each of the three items is a caller-assigned integer 1, 2, 3, or 4 from Payen 2001 Table 1. magent does not observe the patient.
- Not CPOT (CPOT items are 0-2). Total is 3-12. magent does not add pain-present cutoffs that are not in Payen 2001.

## Formula

```
BPS = facial_expression + upper_limbs + ventilator_compliance; each caller-assigned 1-4; range 3-12
```

## Citation

[Assessing pain in critically ill sedated patients by using a behavioral pain scale](https://doi.org/10.1097/00003246-200112000-00004)
Payen JF, Bru O, Bosson JL, Lagrasta A, Novel E, Deschaux I, Lavagne P, Jacquot C
Crit Care Med. 2001;29(12):2258-2263
DOI: [10.1097/00003246-200112000-00004](https://doi.org/10.1097/00003246-200112000-00004)

## Worked example

### All items 1

Given: `facial_expression=1, upper_limbs=1, ventilator_compliance=1`

1. facial_expression 1 + upper_limbs 1 + ventilator_compliance 1
2. Score = 3 (max 12)


### All items 4

Given: `facial_expression=4, upper_limbs=4, ventilator_compliance=4`

1. facial_expression 4 + upper_limbs 4 + ventilator_compliance 4
2. Score = 12 (max 12)


## Also searched as

- BPS
- Behavioral Pain Scale
- Payen BPS
- Payen 2001 BPS
- behavioural pain scale
- ICU behavioral pain

## Parameters

- `facial_expression` (integer, required): Caller-assigned Payen 2001 BPS facial expression (integer 1-4): 1 relaxed; 2 partially tightened (e.g. brow lowering); 3 fully tightened (e.g. eyelid closing); 4 grimacing. magent does not observe the patient.
- `upper_limbs` (integer, required): Caller-assigned Payen 2001 BPS upper limbs (integer 1-4): 1 no movement; 2 partially bent; 3 fully bent with finger flexion; 4 permanently retracted. magent does not observe the patient.
- `ventilator_compliance` (integer, required): Caller-assigned Payen 2001 BPS compliance with ventilation (integer 1-4): 1 tolerating movement; 2 coughing but tolerating ventilation most of the time; 3 fighting ventilator; 4 unable to control ventilation. magent does not observe the patient.

## 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/bps`
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": [
    {
      "facial_expression": "1",
      "upper_limbs": "1",
      "ventilator_compliance": "1"
    },
    {
      "facial_expression": "1",
      "upper_limbs": "1",
      "ventilator_compliance": "1"
    }
  ]
}
```

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

Example 200:

```json
{
  "count": 2,
  "path": "/api/calc/bps",
  "items": [
    {
      "components": [
        {
          "value": 1,
          "factor": "facial_expression",
          "points": 1,
          "present": true
        },
        {
          "value": 1,
          "factor": "upper_limbs",
          "points": 1,
          "present": true
        },
        {
          "value": 1,
          "factor": "ventilator_compliance",
          "points": 1,
          "present": true
        }
      ],
      "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": "Payen JF, Bru O, Bosson JL, Lagrasta A, Novel E, Deschaux I, Lavagne P, Jacquot C",
        "doi": "10.1097/00003246-200112000-00004",
        "id": "payen-2001",
        "pmid": "11700385",
        "source": "Crit Care Med. 2001;29(12):2258-2263",
        "title": "Assessing pain in critically ill sedated patients by using a behavioral pain scale"
      },
      "formula": "bps",
      "formula_expression": "BPS = facial_expression + upper_limbs + ventilator_compliance; each caller-assigned 1-4; range 3-12",
      "max_score": 12,
      "score": 3,
      "facial_expression": 1,
      "upper_limbs": 1,
      "ventilator_compliance": 1
    },
    {
      "components": [
        {
          "value": 1,
          "factor": "facial_expression",
          "points": 1,
          "present": true
        },
        {
          "value": 1,
          "factor": "upper_limbs",
          "points": 1,
          "present": true
        },
        {
          "value": 1,
          "factor": "ventilator_compliance",
          "points": 1,
          "present": true
        }
      ],
      "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": "Payen JF, Bru O, Bosson JL, Lagrasta A, Novel E, Deschaux I, Lavagne P, Jacquot C",
        "doi": "10.1097/00003246-200112000-00004",
        "id": "payen-2001",
        "pmid": "11700385",
        "source": "Crit Care Med. 2001;29(12):2258-2263",
        "title": "Assessing pain in critically ill sedated patients by using a behavioral pain scale"
      },
      "formula": "bps",
      "formula_expression": "BPS = facial_expression + upper_limbs + ventilator_compliance; each caller-assigned 1-4; range 3-12",
      "max_score": 12,
      "score": 3,
      "facial_expression": 1,
      "upper_limbs": 1,
      "ventilator_compliance": 1
    }
  ]
}
```

## Response fields

- `formula` (string): bps
- `formula_expression` (string): Exact expression used
- `score` (integer): BPS points 3-12
- `max_score` (integer): Always 12
- `facial_expression` (integer): Caller-assigned facial expression 1-4
- `upper_limbs` (integer): Caller-assigned upper limbs 1-4
- `ventilator_compliance` (integer): Caller-assigned compliance with ventilation 1-4
- `components` (array): Per-item caller-assigned points
- `citation` (object): Payen et al. Crit Care Med 2001 citation
- `disclaimer` (string): Not-a-device notice

## Example JSON

Frozen fixture. Not a live lookup.

```json
{
  "components": [
    {
      "value": 1,
      "factor": "facial_expression",
      "points": 1,
      "present": true
    },
    {
      "value": 1,
      "factor": "upper_limbs",
      "points": 1,
      "present": true
    },
    {
      "value": 1,
      "factor": "ventilator_compliance",
      "points": 1,
      "present": true
    }
  ],
  "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": "Payen JF, Bru O, Bosson JL, Lagrasta A, Novel E, Deschaux I, Lavagne P, Jacquot C",
    "doi": "10.1097/00003246-200112000-00004",
    "id": "payen-2001",
    "pmid": "11700385",
    "source": "Crit Care Med. 2001;29(12):2258-2263",
    "title": "Assessing pain in critically ill sedated patients by using a behavioral pain scale"
  },
  "formula": "bps",
  "formula_expression": "BPS = facial_expression + upper_limbs + ventilator_compliance; each caller-assigned 1-4; range 3-12",
  "max_score": 12,
  "score": 3,
  "facial_expression": 1,
  "upper_limbs": 1,
  "ventilator_compliance": 1
}
```

## Errors

- HTTP 400 `invalid_bps`: facial_expression, upper_limbs, and ventilator_compliance must each be an integer 1, 2, 3, or 4 (Payen 2001). 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

- [CPOT](https://magentlab.com/docs/cpot) — Sum four caller-assigned Gélinas 2006 CPOT integers (0-2) and return the published total (max 8). The fourth item is ventilator_compliance when intubated or vocalization when extubated.

## 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.