Altitude-Adjusted PERC Rule

Emergency medicinePulmonary embolismClinical decision ruleBeta toolThis tool is in beta. It has undergone internal validation but still requires additional testing. Always confirm the data entered and the results obtained before clinical use. It should not be used as the sole basis for clinical decisions.

Low-risk by clinician gestalt (<15% pretest probability)This must be explicitly confirmed before the rule can support PE rule-out.

YesNo

Age

The age criterion stays negative only when age is strictly below 50 years.

years

Heart rate

The pulse criterion stays negative only when heart rate is strictly below 100 beats/min.

beats/min

Oxygen saturation

In the published high-altitude setting, the oxygen criterion stays negative at 90% or higher.

Hemoptysis present

YesNo

Estrogen use

YesNo

Surgery or trauma requiring hospitalization within 4 weeks

YesNo

Prior venous thromboembolism

YesNo

Unilateral leg swelling

YesNo

Enter the data

The result appears automatically once all required fields are complete.

Clinical noticeEducational decision-support only. Do not generalize the 90% oxygen cutoff beyond the published high-altitude setting.

Context and use

Altitude-adjusted PERC is negative only if the patient is already low risk and every criterion is negative: age <50, heart rate <100/min, SpO2 >=90%, no hemoptysis, no estrogen use, no surgery or trauma requiring hospitalization within 4 weeks, no prior VTE, and no unilateral leg swelling.

The only change from standard PERC in this implementation is the oxygen cutoff: 90% instead of 95% in the published 4980 ft (1518 m) ED setting.