CPAP and home oxygen: the specific test numbers that decide coverage
Checked against the current rules on September 22, 2026.
CPAP and home oxygen are two of the more mechanical coverage rules — each is governed by a specific test result, not a general clinical impression, which makes a wrongly-denied case unusually easy to spot.
Source: Medicare Coverage Database — National Coverage Determinations.
CPAP requires a sleep test (polysomnogram or home sleep test) showing an AHI/RDI of 15 or more events per hour, or 5-14 with specific documented symptoms (daytime sleepiness, hypertension, a prior stroke, and similar).NCD 240.4
Home oxygen requires a qualifying hypoxemia test — an arterial blood gas or pulse oximetry reading at or below specific thresholds — ordered and evaluated by the treating practitioner.NCD 240.2
Because both tests produce an exact number, a denial that doesn't cite the actual test result, or that applied a different number than the rule requires, is often a straightforward appeal to win.
What this means for your appeal
Request a copy of the actual sleep-test or blood-gas report if the family doesn't already have it — the specific AHI/RDI number, or the specific oxygen saturation/pressure reading, is the single fact these appeals turn on, and a denial that doesn't reference it may not have actually checked it.
For CPAP in the 5-14 AHI/RDI range, the qualifying symptoms (daytime sleepiness, hypertension, a history of stroke, and similar) need to be specifically documented by the physician — a test result in that range without documented symptoms doesn't meet the standard on its own.
Continued coverage (after the initial trial period) for both CPAP and oxygen typically requires evidence the treatment is actually being used and is helping — a compliance download for CPAP, or a follow-up test for oxygen — so keeping that documentation on hand matters for a later denial, not just the first one.
Both NCDs also require the sleep test or blood-gas test to be interpreted and ordered by a qualified practitioner, and — for CPAP specifically — a face-to-face clinical evaluation before the sleep test. A denial that skips past these procedural requirements to focus only on the numeric threshold hasn't addressed the whole rule.
Local Coverage Determinations sometimes add further documentation detail on top of the national rule for the same equipment — worth checking alongside the NCD itself if a denial cites requirements beyond what's described here.
Sources — last checked September 22, 2026
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By CaseWhy Appeals editorial. See how this content is produced. Not legal advice. Not affiliated with or endorsed by Medicare, CMS, or any health plan. A product of CaseWhy LLC.
