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Altitude-Adjusted PERC Rule (Madsen 2019) — PERC at ~4980 ft
x402
Altitude-Adjusted PERC Rule (Madsen 2019) — PERC at ~4980 ft is a paid API for AI agents from api.magentlab.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-14).
Evaluates all eight PERC criteria with the Madsen 2019 altitude adjustment (SpO2 threshold ≥90% instead of ≥95%) to determine if a low-pretest-probability patient is PERC-negative for pulmonary embolism at high altitude.
Price / call$0.005
Success—
StatusUnknown
How this service works
Altitude-adjusted PERC (Madsen 2019). Same eight Kline factors as sea-level PERC except hypoxia is O2 sat <90% at ~4980 ft, not <95%. PERC-negative only when all eight hold: age <50, pulse <100, SaO2 ≥90%, and no unilateral leg swelling, hemoptysis, recent trauma or surgery, prior PE or DVT, or hormone use. Caller must already have low pretest probability as in Kline. Not a PE diagnosis, not sea-level PERC, and not a medical device.
Output
Returns a structured object indicating whether the patient is PERC-negative under the Madsen 2019 altitude adjustment (SpO2 threshold ≥90%), along with the status of each of the eight criteria. A PERC-negative result requires all eight criteria to be simultaneously met: age <50, pulse <100, SpO2 ≥90%, and absence of unilateral leg swelling, hemoptysis, recent surgery/trauma, prior VTE, and hormone use.
Example use cases
ED triage for PE at altitude
“I have a 38-year-old ED patient at a high-altitude facility with heart rate 94, oxygen sat 92%, no leg swelling, no hemoptysis, no recent trauma or surgery, no prior blood clots, and no hormone use — run the Madsen 2019 altitude PERC rule to see if I can rule out PE without imaging.”
Telemedicine PE screening for mountain clinic
“Patient is 55 years old, pulse 72, SpO2 90%, no unilateral leg swelling, no coughing up blood, no recent surgery or trauma, no history of PE or DVT, and no estrogen use — apply the altitude-adjusted PERC rule and tell me if they're PERC-negative.”
Clinical decision support tool integration
“For my clinical workflow at ~5000 feet elevation, check this patient: age 47, heart rate 85 bpm, SpO2 93%, unilateral leg swelling present, no hemoptysis, no recent surgery, no prior VTE, no hormone use — does this patient meet all eight altitude-adjusted PERC criteria?”
Technical details
Endpoint
GEThttps://api.magentlab.com/api/calc/perc_altitudeWhen to prefer
Choose this endpoint when evaluating a patient at approximately 4980 feet (high altitude) who already has low pretest probability for PE (per Kline criteria) and you need the Madsen 2019 altitude-adjusted SpO2 threshold (≥90%) rather than the standard sea-level PERC cutoff (>94%). Do not use for sea-level patients — use a standard PERC calculator instead. Not a medical device or diagnostic tool; clinical judgment required.
Side effects
- Missing required query parameters (age, heart_rate_bpm, spo2_percent, or any boolean field) returns a validation error
- Age outside the valid range (18–120) may be rejected
- SpO2 outside 50–100 range may be rejected
- Heart rate outside 30–220 bpm may be rejected
- Caller has high pretest probability — rule is only valid with low pretest probability as per Kline criteria (caller responsibility)
- Confusing sea-level PERC (SpO2 >94%) with this altitude-adjusted version (SpO2 ≥90%) leads to incorrect criterion application
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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