Altitude-Adjusted PERC Rule for PE
Modified Pulmonary Embolism Rule-out Criteria (PERC) adjusted for altitude. At high altitudes (>4000 ft/1220 m), physiological SpO₂ is lower, so the cut-off is adjusted from 95% to 90% to maintain specificity.
Score interpretation
→ PERC Negative (0 criteria): In a low pre-test probability patient, no further workup required for PE. Risk is <2%. No D-dimer or CT-PA needed. Apply only if gestalt pre-test probability is LOW.
→ PERC Positive (≥1 criterion): Cannot rule out PE with PERC. Proceed to D-dimer (if pre-test probability low-moderate) or CT-PA (if high probability). Use Wells score to guide D-dimer vs direct CT-PA.
Interpretation bands for the Altitude PERC. Apply clinical judgement and local guidance.
References
Related
Curated clinical cross-links plus same-class fallbacks.
- Hydroxocobalamin (High-Dose — Cyanide Antidote) · Cyanide Antidote (Vitamin B12 Precursor at High Dose)
- Nitric Oxide (Inhaled — iNO) · Selective Pulmonary Vasodilator
- Selexipag · Pulmonary Arterial Hypertension
- Macitentan · Pulmonary Arterial Hypertension
- Thiamine (IV/IM — Pabrinex) · Vitamin B1 (Thiamine) — deficiency treatment / Wernicke's encephalopathy prevention
- Calcium chloride · IV calcium salt (high elemental calcium)
- Acute Asthma in Adults · BTS/SIGN British Guideline on Asthma 2019; NICE NG80
- Pulmonary Embolism Assessment · NICE NG158; ESC 2019 PE Guidelines
- Acute Exacerbation of COPD (AECOPD) · NICE NG115; GOLD 2024
- Spontaneous Pneumothorax (Adult) · BTS Pleural Disease 2023
- Atypical Pneumonia (Legionella / Mycoplasma / Chlamydophila) · BTS 2023; IDSA
- COPD Exacerbation Management · NICE NG115 / GOLD 2024
Decision support only — verify against a current formulary, NICE, or your local guideline before clinical use.