Hematology · LIVE

Kaplan plasma volume

Compute Kaplan 1990 estimated plasma volume for therapeutic plasma exchange from weight and hematocrit as a percent, returning one plasma volume in liters and milliliters.

LIVE $0.005 USDC GET /api/calc/tpe

Markdown: /docs/tpe.md · Canonical: https://magentlab.com/docs/tpe

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

What it computes

Compute Kaplan 1990 estimated plasma volume for therapeutic plasma exchange from weight and hematocrit as a percent, returning one plasma volume in liters and milliliters.

When to use

When an agent needs published Kaplan plasma volume and must not invent a 1.5-PV exchange, a removal-percent band, Nadler blood volume, or an apheresis order.

When not to use

• Not a medical device. magent does not write an apheresis prescription, choose a replacement fluid, or schedule sessions.
• Hematocrit is hematocrit_percent (10-70). A 0-1 fraction is not accepted.
• Kaplan 1990 estimated plasma volume only (one plasma volume). 1.5-PV volumes and immunoglobulin-removal percents are later reviews (Kaplan 2013), not this tool.
• Not Nadler blood volume and not Ganzoni iron deficit.

Formula

epv_l = 0.065 * weight_kg * (1 - hematocrit_fraction)

Citation

Title

A simple and accurate method for prescribing plasma exchange

Authors

Kaplan AA

Source

ASAIO Trans. 1990;36(3):M597-M599

DOI

none

Worked example

Also searched as

• therapeutic plasma exchange estimated plasma volume
• Kaplan plasma volume
• estimated plasma volume
• EPV TPE
• plasma exchange volume
• Kaplan EPV
• Kaplan 1990 plasma volume
• TPE plasma volume

Try

Opens the live endpoint. Unpaid browser requests show the paywall; agents should send Accept: application/json.

/api/calc/tpe?weight_kg=70&hematocrit_percent=40

Full URL: https://api.magentlab.com/api/calc/tpe?weight_kg=70&hematocrit_percent=40

Call

Expect HTTP 402 until you retry with PAYMENT-SIGNATURE. Incomplete query params return HTTP 400 before any quote or charge.

curl -i -H "Accept: application/json" "https://api.magentlab.com/api/calc/tpe?weight_kg=70&hematocrit_percent=40"

Parameters

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.

POST /api/calc/tpe Max 25 unit_amount + extra_item_amount * (n - 1) extra $0.002 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 (fixture)

{
  "items": [
    {
      "hematocrit_percent": "40",
      "weight_kg": "70"
    },
    {
      "hematocrit_percent": "40",
      "weight_kg": "70"
    }
  ]
}

Open bulk paywall →

Opens a two-item fixture on the API host. Unpaid browsers get the same MetaMask paywall as GET; Pay retries POST with those items.

Example 200 (fixture)

{
  "count": 2,
  "path": "/api/calc/tpe",
  "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": "Kaplan AA",
        "id": "kaplan-1990",
        "pmid": "2252761",
        "source": "ASAIO Trans. 1990;36(3):M597-M599",
        "title": "A simple and accurate method for prescribing plasma exchange"
      },
      "formula": "kaplan_1990",
      "formula_expression": "epv_l = 0.065 * weight_kg * (1 - hematocrit_fraction)",
      "hematocrit_percent": 40.0,
      "weight_kg": 70.0,
      "epv_l": 2.73,
      "one_pv_ml": 2730.0
    },
    {
      "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": "Kaplan AA",
        "id": "kaplan-1990",
        "pmid": "2252761",
        "source": "ASAIO Trans. 1990;36(3):M597-M599",
        "title": "A simple and accurate method for prescribing plasma exchange"
      },
      "formula": "kaplan_1990",
      "formula_expression": "epv_l = 0.065 * weight_kg * (1 - hematocrit_fraction)",
      "hematocrit_percent": 40.0,
      "weight_kg": 70.0,
      "epv_l": 2.73,
      "one_pv_ml": 2730.0
    }
  ]
}

Response

Example JSON

Machine form of the same example. Frozen fixture. Not a live lookup.

{
  "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": "Kaplan AA",
    "id": "kaplan-1990",
    "pmid": "2252761",
    "source": "ASAIO Trans. 1990;36(3):M597-M599",
    "title": "A simple and accurate method for prescribing plasma exchange"
  },
  "formula": "kaplan_1990",
  "formula_expression": "epv_l = 0.065 * weight_kg * (1 - hematocrit_fraction)",
  "hematocrit_percent": 40.0,
  "weight_kg": 70.0,
  "epv_l": 2.73,
  "one_pv_ml": 2730.0
}

Client errors (HTTP 400)

Invalid params return 400 without charge. Shared HTTP 402 and 503 meanings: Payments.

Related tools

• Ganzoni iron deficit — Compute the Ganzoni 1970 iron deficit from weight, measured hemoglobin, a caller-supplied target hemoglobin, and depot iron stores.
• Allowable blood loss — Compute Gross 1983 dilution-corrected allowable blood loss from a caller-supplied estimated blood volume and initial versus target hematocrit.

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. Unpaid valid requests return HTTP 402 with a base64 PAYMENT-REQUIRED header. HTTP 503 is not a new quote: retry the same PAYMENT-SIGNATURE. Full handshake and shared payment errors: Payments. Stdio MCP: /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.