# Kaplan plasma volume Kaplan plasma volume Status: LIVE Price: $0.005 USDC `GET /api/calc/tpe` HTML: https://magentlab.com/docs/tpe Markdown: https://magentlab.com/docs/tpe.md 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 [A simple and accurate method for prescribing plasma exchange](https://pubmed.ncbi.nlm.nih.gov/2252761) Kaplan AA ASAIO Trans. 1990;36(3):M597-M599 DOI: none ## Worked example ### 70 kg, hematocrit 40 percent Given: `hematocrit_percent=40, weight_kg=70` 1. hematocrit_fraction = 40 / 100 = 0.40 2. epv_l = 0.065 * 70 * (1 - 0.40) = 0.065 * 70 * 0.60 = 2.73 L 3. one_pv_ml = 2.73 * 1000 = 2730 mL ## 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 ## Parameters - `weight_kg` (number, optional): Weight in kilograms. Provide weight_kg or weight_lb. - `weight_lb` (number, optional): Weight in pounds. Converted as kg = lb * 0.45359237. - `hematocrit_percent` (number, required): Hematocrit as a percent (10-70). Required. Not a 0-1 fraction; magent does not accept hematocrit_fraction. ## 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/tpe` 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": [ { "hematocrit_percent": "40", "weight_kg": "70" }, { "hematocrit_percent": "40", "weight_kg": "70" } ] } ``` Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/tpe Example 200: ```json { "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 fields - `formula` (string): kaplan_1990 - `formula_expression` (string): Exact Kaplan 1990 EPV expression - `weight_kg` (number): Normalized weight in kg - `hematocrit_percent` (number): Hematocrit percent used - `epv_l` (number): Estimated plasma volume in liters, 2 decimals - `one_pv_ml` (number): Same EPV in milliliters (epv_l * 1000), 0 decimals - `citation` (object): Kaplan ASAIO Trans 1990 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": "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 } ``` ## Errors - HTTP 400 `invalid_weight`: weight_kg (1-500) or weight_lb (2-1100) is required Returned before settlement; you are not charged. - HTTP 400 `invalid_hematocrit`: hematocrit_percent must be a number from 10 to 70. 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 - [Ganzoni iron deficit](https://magentlab.com/docs/ganzoni) — Compute the Ganzoni 1970 iron deficit from weight, measured hemoglobin, a caller-supplied target hemoglobin, and depot iron stores. - [Allowable blood loss](https://magentlab.com/docs/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. - 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.