U.S. home oxygen comes in four basic forms, and many patients use two: one at home, one for getting out. Here’s how they compare, using CMS Medicare policy, the American Thoracic Society (ATS) guideline and VA patient-safety data.
The four modalities
| Modality | How it works | Needs power? | Refills? | Typical role |
|---|---|---|---|---|
| Stationary concentrator | Makes oxygen from room air | Yes | No | Main home source; the VA says concentrators are the most common source |
| Gaseous cylinders | Compressed oxygen in tanks | No | Yes, delivered or home-filled | Portable use, backup in outages |
| Liquid oxygen | Liquid oxygen in a home reservoir; you fill portable units | No | Yes, reservoir deliveries | Higher-flow mobility (ATS) |
| Portable concentrator (POC) | Battery concentrator; CMS requires at least 85% concentration | Battery/AC/DC | No | Mobility and travel |
| Transfill (home fill) | Stationary concentrator feature that fills your own portable cylinders | Yes | Self-filled | Mobility without deliveries |
Sources: CMS A52514, VA AL18-01, ATS 2020.
What the ATS guideline adds
The ATS 2020 home oxygen guideline suggests portable liquid oxygen for mobile patients who need continuous flow above 3 L/min during exertion (conditional recommendation). It also recommends that patients and caregivers get education on equipment and safety (ATS). Many POCs are pulse-dose only, so check that one meets your exertional prescription: see pulse dose vs continuous flow.
Medicare rules that shape your choice
| Rule | What CMS says | Source |
|---|---|---|
| Contents included | Payment for stationary and portable oxygen contents is included in the stationary equipment allowance during rental | A52514 |
| After month 36 | If you used gaseous or liquid equipment in the 36th month, contents payments can continue | A52514 |
| POC definition (E1392) | Portable, 85% or greater oxygen, runs on AC or DC, batteries giving at least 2 hours at 2 LPM equivalency, total weight with those batteries 20 lb or less | A52514 |
| Transfill | K0738 (fills gaseous cylinders) or E0433 (fills liquid); when billed, the separate portable gaseous (E0431) or liquid (E0434) system code isn’t used | A52514 |
| Changing modality | Not allowed unless: replaced with the same or equivalent item; your treating practitioner orders different equipment; you choose an upgrade and sign an ABN; or CMS/DME MAC decides it’s warranted | A52514 |
| Concentrator maintenance | After 36 months, concentrator or transfill users may owe coinsurance for maintenance every 6 months, when the supplier visits | Medicare.gov |
So if you want a POC instead of cylinders, the practical route is a new order from your clinician. See Medicare home oxygen coverage.
Head-to-head
| Factor | Concentrator (stationary) | Cylinders | Liquid | POC |
|---|---|---|---|---|
| Works in a power outage | No | Yes | Yes | Battery only |
| Delivery dependence | None | Yes (unless transfill) | Yes | None |
| Electricity cost | Yes (cost guide) | No | No | Charging |
| Fire risk | Yes | Yes | Yes | Yes |
| Night use | Continuous flow | Ask your supplier about duration | Ask your supplier about duration | Depends on model (POCs for sleeping) |
The VA notes that concentrators, cylinders and liquid reservoirs “all three sources pose a risk of accelerated combustion” (VA).
Storing cylinders safely
MedlinePlus says don’t store oxygen in a trunk, box or small closet; under the bed is OK if air moves freely; and keep oil-, grease- or alcohol-based cleaners away (MedlinePlus). Follow your supplier’s instructions for securing cylinders. More in home oxygen fire safety.
What we left out
How long a cylinder lasts depends on its size, fill and your flow. We didn’t find a primary U.S. source with a duration table we could cite, so we don’t publish one. Ask your supplier for the duration chart for the exact cylinders and regulator or conserver they provide.
Verdict
For most people a stationary concentrator at home plus a portable option is the standard set-up. Choose cylinders or transfill if you want a backup that works without power, liquid if you need high continuous flow on the move (per ATS), and a POC if its delivery matches your prescription. Under Medicare, changing type needs a practitioner’s order or another allowed reason, so start with your clinician.
Related: oxygen concentrator buyer’s guide, 5 LPM vs 10 LPM, switching Medicare oxygen suppliers.