# Brescia-COVID Respiratory Severity Scale

BCRSS

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

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

## What it computes

Count the four Duca 2020 BCRSS testing-criteria binaries as assigned by the caller and return the integer total (0–4).

## When to use

When an agent already has the four Duca 2020 testing-criteria flags and needs the published 0–4 count. magent does not examine the patient, count breaths, measure SpO2 or PaO2, or read imaging.

## When not to use

- Not a medical device and not a COVID-19 diagnosis or ventilator order. magent does not examine the patient or read imaging.
- This is the Duca 2020 testing-criteria count only (four caller-assigned binaries; 0–4). It is not the 0–8 NIV, intubation, proning, or neuromuscular-blockade ladder.
- The caller assigns wheezing or inability to speak in full sentences, respiratory rate >22, PaO2 <65 mmHg or SpO2 <90%, and significant chest-radiograph worsening. magent does not measure vitals or interpret radiographs.
- The scale was rapidly developed in Brescia during the 2020 crisis and has not been validated in other populations. magent returns the integer count only.

## Formula

```
bcrss = wheezing_or_unable_full_sentences + respiratory_rate_gt_22 + pao2_lt_65_or_spo2_lt_90 + chest_radiograph_worsening; each 1 if true; Duca 2020 BCRSS testing criteria; max 4
```

## Citation

[Calculated Decisions: Brescia-COVID Respiratory Severity Scale (BCRSS)/Algorithm](https://pubmed.ncbi.nlm.nih.gov/32297727)
Duca A, Piva S, Focà E, Latronico N, Rizzi M
Emerg Med Pract. 2020 Apr 16;22(5 Suppl):CD1-CD2
DOI: none

## Worked example

### All four testing criteria false

Given: `chest_radiograph_worsening=false, pao2_lt_65_or_spo2_lt_90=false, respiratory_rate_gt_22=false, wheezing_or_unable_full_sentences=false`

1. wheezing_or_unable_full_sentences false
2. respiratory_rate_gt_22 false
3. pao2_lt_65_or_spo2_lt_90 false
4. chest_radiograph_worsening false
5. bcrss = 0 (max 4). Integer count only; not a diagnosis or ventilator order.


### Isolated respiratory rate >22

Given: `chest_radiograph_worsening=false, pao2_lt_65_or_spo2_lt_90=false, respiratory_rate_gt_22=true, wheezing_or_unable_full_sentences=false`

1. respiratory_rate_gt_22 true is one testing criterion
2. The other three flags are false
3. bcrss = 1 (max 4). Integer count only.


## Also searched as

- BCRSS
- Brescia-COVID Respiratory Severity Scale
- Brescia COVID
- Duca BCRSS
- BCRSS algorithm
- Brescia-COVID scale
- COVID respiratory severity
- BCRSS testing criteria

## Parameters

- `wheezing_or_unable_full_sentences` (boolean, required): Wheezing or inability to speak in full sentences while at rest or with minimal effort, as assigned by the caller (Duca 2020 testing criterion 1). true or false. magent does not examine the patient.
- `respiratory_rate_gt_22` (boolean, required): Respiratory rate >22 breaths/min as assigned by the caller (Duca 2020 testing criterion 2). true or false. magent does not count breaths.
- `pao2_lt_65_or_spo2_lt_90` (boolean, required): PaO2 <65 mmHg or SpO2 <90% as assigned by the caller (Duca 2020 testing criterion 3). true or false. magent does not measure SpO2 or PaO2.
- `chest_radiograph_worsening` (boolean, required): Significant worsening on chest radiograph as assigned by the caller (Duca 2020 testing criterion 4). true or false. magent does not read imaging.

## 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/brescia_covid`
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": [
    {
      "chest_radiograph_worsening": "false",
      "pao2_lt_65_or_spo2_lt_90": "false",
      "respiratory_rate_gt_22": "false",
      "wheezing_or_unable_full_sentences": "false"
    },
    {
      "chest_radiograph_worsening": "false",
      "pao2_lt_65_or_spo2_lt_90": "false",
      "respiratory_rate_gt_22": "false",
      "wheezing_or_unable_full_sentences": "false"
    }
  ]
}
```

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

Example 200:

```json
{
  "count": 2,
  "path": "/api/calc/brescia_covid",
  "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": "Duca A, Piva S, Focà E, Latronico N, Rizzi M",
        "id": "duca-2020",
        "pmid": "32297727",
        "source": "Emerg Med Pract. 2020 Apr 16;22(5 Suppl):CD1-CD2",
        "title": "Calculated Decisions: Brescia-COVID Respiratory Severity Scale (BCRSS)/Algorithm"
      },
      "formula": "brescia_covid",
      "formula_expression": "bcrss = wheezing_or_unable_full_sentences + respiratory_rate_gt_22 + pao2_lt_65_or_spo2_lt_90 + chest_radiograph_worsening; each 1 if true; Duca 2020 BCRSS testing criteria; max 4",
      "max_score": 4,
      "criteria": [
        {
          "factor": "wheezing_or_unable_full_sentences",
          "met": false
        },
        {
          "factor": "respiratory_rate_gt_22",
          "met": false
        },
        {
          "factor": "pao2_lt_65_or_spo2_lt_90",
          "met": false
        },
        {
          "factor": "chest_radiograph_worsening",
          "met": false
        }
      ],
      "bcrss": 0
    },
    {
      "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": "Duca A, Piva S, Focà E, Latronico N, Rizzi M",
        "id": "duca-2020",
        "pmid": "32297727",
        "source": "Emerg Med Pract. 2020 Apr 16;22(5 Suppl):CD1-CD2",
        "title": "Calculated Decisions: Brescia-COVID Respiratory Severity Scale (BCRSS)/Algorithm"
      },
      "formula": "brescia_covid",
      "formula_expression": "bcrss = wheezing_or_unable_full_sentences + respiratory_rate_gt_22 + pao2_lt_65_or_spo2_lt_90 + chest_radiograph_worsening; each 1 if true; Duca 2020 BCRSS testing criteria; max 4",
      "max_score": 4,
      "criteria": [
        {
          "factor": "wheezing_or_unable_full_sentences",
          "met": false
        },
        {
          "factor": "respiratory_rate_gt_22",
          "met": false
        },
        {
          "factor": "pao2_lt_65_or_spo2_lt_90",
          "met": false
        },
        {
          "factor": "chest_radiograph_worsening",
          "met": false
        }
      ],
      "bcrss": 0
    }
  ]
}
```

## Response fields

- `formula` (string): brescia_covid
- `formula_expression` (string): Duca 2020 BCRSS testing-criteria count of four binaries
- `bcrss` (integer): Count of true testing criteria (0-4). Not a diagnosis or ventilator order.
- `max_score` (integer): Always 4
- `criteria` (array): Per-criterion Tree rows with factor and met
- `citation` (object): Duca 2020 Emerg Med Pract 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": "Duca A, Piva S, Focà E, Latronico N, Rizzi M",
    "id": "duca-2020",
    "pmid": "32297727",
    "source": "Emerg Med Pract. 2020 Apr 16;22(5 Suppl):CD1-CD2",
    "title": "Calculated Decisions: Brescia-COVID Respiratory Severity Scale (BCRSS)/Algorithm"
  },
  "formula": "brescia_covid",
  "formula_expression": "bcrss = wheezing_or_unable_full_sentences + respiratory_rate_gt_22 + pao2_lt_65_or_spo2_lt_90 + chest_radiograph_worsening; each 1 if true; Duca 2020 BCRSS testing criteria; max 4",
  "max_score": 4,
  "criteria": [
    {
      "factor": "wheezing_or_unable_full_sentences",
      "met": false
    },
    {
      "factor": "respiratory_rate_gt_22",
      "met": false
    },
    {
      "factor": "pao2_lt_65_or_spo2_lt_90",
      "met": false
    },
    {
      "factor": "chest_radiograph_worsening",
      "met": false
    }
  ],
  "bcrss": 0
}
```

## Errors

- HTTP 400 `invalid_flag`: boolean clinical flags must be true or false 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

- [qCSI](https://magentlab.com/docs/qcsi) — Sum Haimovich 2020 qCSI bedside points (Table 2) from respiratory rate, lowest SpO2, and nasal-cannula oxygen flow and return the integer total (max 12).
- [LIPS](https://magentlab.com/docs/lips) — Sum Gajic 2011 Table 3 lung injury prediction score items from caller-assigned flags and return the published ROC cutoff band (low <4, high ≥4).

## 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.