Calculate your Apnea-Hypopnea Index from sleep study data. Includes supine AHI, REM AHI, positional analysis, severity grading, and treatment recommendations.
The AHI (Apnea-Hypopnea Index) Calculator computes your apnea-hypopnea index from sleep study data, providing severity classification, positional analysis (supine vs. non-supine), REM-dependent analysis, and evidence-based treatment recommendations.
The AHI is the primary metric used to diagnose and classify obstructive sleep apnea (OSA), the most common sleep-related breathing disorder affecting an estimated 936 million adults worldwide. It measures the number of complete airflow cessations (apneas) and partial reductions (hypopneas) per hour of sleep. An AHI ≥5 with symptoms or ≥15 regardless of symptoms establishes the diagnosis of OSA.
Beyond the overall AHI, this calculator provides critical sub-analyses that influence treatment selection. Positional OSA (supine AHI ≥2× non-supine AHI) may respond to positional therapy alone. REM-dependent OSA (REM AHI ≥2× overall AHI) has specific clinical implications. The SpO₂ nadir assessment provides additional context about hypoxic burden, which independently predicts cardiovascular risk. It keeps the report data grouped so the main severity score and the subgroup values can be reviewed together. Check the example with realistic values before reporting.
Sleep study reports often include multiple event counts, oxygen values, and subgroup analyses that are difficult to compare at a glance. This calculator keeps the core AHI context together with positional and REM-specific breakdowns so the same report can be reviewed more consistently and interpreted without losing the main sleep-study structure. It is useful when you need a concise summary of the study rather than a page of separate numbers.
AHI = (Total Apneas + Total Hypopneas) / Total Sleep Time (hours) Apnea: Complete airflow cessation ≥10 seconds Hypopnea: ≥30% airflow reduction with ≥3% SpO₂ desaturation or arousal (AASM 2012) Supine AHI = Supine events / Supine time Positional OSA: Supine AHI ≥ 2× Non-supine AHI
Result: AHI = 15.0 events/hr — Moderate OSA
With 105 total events over 7 hours, the AHI is 15.0, placing this patient in the moderate OSA category. The SpO₂ nadir of 82% indicates moderate hypoxic burden. CPAP therapy is the standard first-line treatment.
A polysomnography report contains far more than the AHI alone. Key metrics include sleep efficiency (>85% is normal), sleep staging distribution (adequate REM and N3 required), periodic limb movement index, central vs. obstructive event classification, and oxygen desaturation index. The AHI remains the primary metric for OSA severity classification and treatment decisions.
Untreated moderate-to-severe OSA is associated with a 2-3× increased risk of hypertension, 2-3× risk of atrial fibrillation, 1.5-2× risk of coronary artery disease, and 1.5-3× risk of stroke. The intermittent hypoxia–reoxygenation cycle causes oxidative stress, systemic inflammation, sympathetic activation, and endothelial dysfunction. Treatment with CPAP shows significant reduction in blood pressure and cardiovascular events.
The OSA treatment landscape is rapidly evolving. Hypoglossal nerve stimulation (Inspire therapy) offers an implantable solution for patients who cannot tolerate CPAP. Tirzepatide and other GLP-1 agonists have shown dramatic AHI reductions through weight loss. Combination positional therapy and oral appliances can achieve significant AHI reduction in selected patients.
AHI counts apneas and hypopneas per hour. RDI (Respiratory Disturbance Index) also includes RERAs (respiratory effort-related arousals), making it a more sensitive but less specific measure. AHI is the standard for OSA diagnosis.
CPAP is indicated for AHI ≥15 (moderate-severe OSA) or AHI 5-14 (mild OSA) with symptoms such as excessive daytime sleepiness, witnessed apneas, or comorbidities like hypertension. Use this as a practical reminder before finalizing the result.
Home sleep tests (Type III) tend to underestimate AHI because they measure recording time rather than actual sleep time. A negative HSAT in a high-probability patient should be followed by in-lab PSG.
Positional OSA occurs when the supine AHI is at least twice the non-supine AHI. These patients may benefit from positional therapy (devices that prevent supine sleep) as standalone or adjunct treatment.
During REM sleep, skeletal muscle tone decreases (atonia), including pharyngeal dilator muscles, making the airway more collapsible. Some patients have OSA only during REM sleep.
Yes. Weight loss of 10-15% can reduce AHI by 50% in obese patients. Positional therapy, oral appliances, myofunctional therapy, and surgeries like UPPP or MMA can also reduce AHI.