{"uid":"cap_FNk83t2SjrWjU9ofzObDT","slug":"altitude-adjusted-perc-rule-madsen-2019-perc-at-4980-ft-8327759a","name":"Altitude-Adjusted PERC Rule (Madsen 2019) — PERC at ~4980 ft","description":"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.","url":"https://api.magentlab.com/api/calc/perc_altitude","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET","HEAD","DELETE"],"type":"string"},"headers":{"type":"object","additionalProperties":{"type":"string"}},"queryParams":{"type":"object","required":["age","heart_rate_bpm","spo2_percent","unilateral_leg_swelling","hemoptysis","recent_surgery_or_trauma","prior_vte","estrogen_use"],"properties":{"age":{"type":"integer","description":"Age in years (18-120). Criterion met when age < 50; 50 does not meet."},"prior_vte":{"type":"boolean","description":"Prior PE or DVT. true or false as assigned by the caller. Criterion met when false."},"hemoptysis":{"type":"boolean","description":"Hemoptysis. true or false as assigned by the caller. Criterion met when false."},"estrogen_use":{"type":"boolean","description":"Hormone or exogenous estrogen use. true or false as assigned by the caller. Criterion met when false."},"spo2_percent":{"type":"number","description":"Oxygen saturation percent (50-100). Criterion met when SaO2 ≥ 90; 89.9 does not meet. Madsen 2019 altitude adjustment, not sea-level PERC >94."},"heart_rate_bpm":{"type":"integer","description":"Pulse in beats per minute (integer 30-220). Criterion met when pulse < 100; 100 does not meet."},"unilateral_leg_swelling":{"type":"boolean","description":"Unilateral leg swelling. true or false as assigned by the caller. Criterion met when false."},"recent_surgery_or_trauma":{"type":"boolean","description":"Recent trauma or surgery. true or false as assigned by the caller. Criterion met when false."}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object"}}}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.005","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.005/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.005","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.005","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_hCkfQ4aVTf1cNZ0JXLKBd","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.005","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"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.","exampleAgentPrompt":"My patient is 43 years old, heart rate 88, SpO2 91%, no unilateral leg swelling, no hemoptysis, no recent surgery or trauma, no prior PE or DVT, and not on any hormones — can you run the altitude-adjusted PERC rule (Madsen 2019) to see if they're PERC-negative?","exampleUseCases":[{"title":"ED triage for PE at altitude","prompt":"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."},{"title":"Telemedicine PE screening for mountain clinic","prompt":"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."},{"title":"Clinical decision support tool integration","prompt":"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?"}],"resultDescription":"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.","failureModes":["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"],"whenToPreferThis":"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.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-14T07:14:23.855Z","isFirstParty":false}