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What this equipment is
E1390 is the HCPCS code for a stationary oxygen concentrrator — a device that concentrates room air into >90% oxygen for delivery to a patient requiring supplemental oxygen therapy. Stationary concentrrators are the primary oxygen delivery method for home use, as opposed to compressed gas (E0431) or liquid oxygen systems.
Stationary oxygen is one of the most heavily audited DME categories. The coverage criteria are specific, the documentation requirements are stringent, and the financial exposure is high — a denied oxygen claim can represent months of rental at $200–$400/month.
Medicare coverage criteria
- Arterial oxygen saturation. For Medicare: PaO2 ≤55 mm Hg OR O2 saturation ≤88% at rest (measured by ABG or pulse oximetry). For patients with concurrent conditions (cor pulmonale, erythrocytosis, or heart failure), the threshold is PaO2 ≤59 mm Hg or O2 sat ≤89%.
- Qualifying test results. The qualifying test must be performed by or under the direction of a physician. Results must be documented in the medical record — a notation that "O2 sat was checked" is insufficient.
- Physician order. A detailed order specifying oxygen, flow rate, and duration of need.
- CMN (Certificate of Medical Necessity). E1390 requires a completed CMN with lab results, physician certification, and length of need.
What actually causes denials in DME back offices
- Oxygen saturation not documented. The most common denial reason. The payer wants a specific number — PaO2 in mm Hg or O2 sat as a percentage — from a specific test, interpreted by a physician. "Patient has low oxygen" without a qualifying test result is not enough.
- Test too old. Medicare requires the qualifying oxygen study to be performed within 30 days before the initial oxygen order. A study from 6 months ago won't support a current order — you need a new test.
- No qualifying diagnosis. The diagnosis on the order and CMN must correspond to a condition known to cause hypoxemia. COPD, ILD, CHF, and neurological disorders are common. "General weakness" or "fatigue" without a documented hypoxemia result won't support coverage.
- No CMN or incomplete CMN. E1390 is one of the DME codes most frequently audited for CMN completeness. Every field must be completed and signed.
- 36-month cap on equipment rental. Stationary oxygen equipment is subject to a 36-month rental cap. After 36 months, ownership transfers to the patient. Billing E1390 after month 36 will be denied — only portable oxygen (E0431) and supplies continue beyond the cap.
Documentation checklist
- Oxygen saturation test (ABG or pulse ox) with qualifying results within 30 days of order
- Physician interpretation and certification of test results
- Detailed order specifying flow rate and duration of need
- Completed CMN with all sections filled and physician signature
- Proof of delivery
Reimbursement note: Medicare's stationary oxygen concentrrator rental rate is approximately $150–$220/month depending on region. After the 36-month cap, the patient owns the equipment and rental claims stop. Portable oxygen contents (E0431) continue to be billable after the stationary oxygen cap. Commercial payer rates vary by contract — verify allowed amounts before billing.
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Frequently asked questions
What qualifies as an oxygen saturation test for E1390?
Arterial blood gas (ABG) measuring PaO2 in mm Hg, or pulse oximetry (SpO2). Either is acceptable, but an ABG gives a PaO2 value directly; pulse ox gives SpO2. Medicare’s thresholds are: PaO2 ≤55 mm Hg or O2 sat ≤88% at rest for standard patients; PaO2 ≤59 mm Hg or O2 sat ≤89% for patients with cor pulmonale, erythrocytosis, or heart failure. The test must be ordered and interpreted by a physician.
After the 36-month oxygen rental cap, can I still bill for anything?
Yes — portable oxygen contents (E0431) and stationary oxygen supplies continue to be covered after the equipment rental cap. Oxygen contents are separately billable regardless of equipment ownership. You cannot bill E1390 rental after month 36, but the patient’s ongoing oxygen therapy coverage continues through supplies.
Can I bill E1390 for a patient using a portable oxygen system only?
No. E1390 is specifically for stationary oxygen concentrrators. Portable oxygen systems use E0431 (gaseous portable) or E0434 (liquid portable). If the patient only uses portable oxygen, bill the appropriate portable code, not E1390.