Table 5.
Characteristics of Portable Oxygen Devices
| Metal Oxygen Cylinders | POCs | LOX | |
|---|---|---|---|
| Size and weight | Available in multiple sizes from 2.5 to 9 kg (E cylinder in United States, which requires a trolley)* | Vary in weight (1.5–10 kg), noise, battery life, oxygen purity (87–95%), maximum breath rates, and settings (pulse flow, continuous flow, or both)†‡ | Medium to large canister ranges between 2.5 and 4 kg |
| Filling | Some stationary concentrators allow patients to fill smaller oxygen cylinders in their home, (home-fill units), but these last <1 h on continuous-flow rates >3 L/min and therefore are inadequate for high-flow patients | No filling; POCs “concentrate” oxygen by extracting nitrogen from ambient air. They run off of a battery and can be recharged | Patients refill portable canisters from a larger home reservoir of LOX |
| One liter of LOX expands to 860 L of gaseous oxygen | |||
| Pulse setting or continuous-flow capacity§ | Oxygen-conserving devices using pulse-flow technology can be attached to metal cylinders to prolong the duration of supply by releasing oxygen only during inspiration | At a given pulse-flow setting, POCs differ as to the volume of oxygen (ml) per pulse, inspiratory time, and triggering sensitivity and may not consistently sense patients’ inspiratory efforts to trigger the device* | Portable LOX technology allows delivery of continuous-flow oxygen up to 15 L/min via a lighter and longer-duration device |
| Because of differences in an individual patient’s ability to trigger a pulse dose of oxygen, and the volume delivered with each pulse at different respiratory rates, they may be insufficient for patients who require continuous oxygen with exertion at >3 L/min, such as those with interstitial lung disease, lung transplantation candidates, and others with severe hypoxemia | Pulse settings are based on an oxygen volume unique to each device, not a standardized L/min methodology | ||
| Duration of supply | A single E tank with a stroller will last approximately 1.9 h on 6 L/min. Multiple cylinders are needed for high-flow (>3 L/min) patients to be out of the home >2–4 h‖ | All POCs depend on a battery supply that depletes more rapidly with higher settings, higher respiratory rates, and the use of continuous-flow settings | A medium LOX canister will last 3 h at 6 L/min of continuous flow |
| Cost | Metal oxygen cylinders range from US$50 to US$100; additional costs for a regulator or oxygen-conserving device. Commonly supplied by U.S. DME companies | In the United States, many DME companies offer POCs as a portable option together with a stationary concentrator; individuals can also purchase them for US$2,000–4,000 | Cost estimates are approximately four times higher per patient compared with POCs or metal-cylinder options because of the requirements for DME companies to access and store LOX, use specially outfitted delivery trucks, and provide weekly refill servicing¶ |
| Travel | Metal cylinders not allowed for air travel | POCs are the only carry-on portable oxygen device allowed by the Federal Aviation Administration for air travel; some airlines may provide oxygen cylinders for emergency in-flight use only** | Liquid oxygen not allowed for air travel |
Definition of abbreviations: DME = durable medical equipment; LOX = liquid oxygen; POCs = portable oxygen concentrators.
The availability of different oxygen devices varies by geographic region, and some jurisdictions do not have smaller metal oxygen cylinders.
The few POCs that currently provide a maximum of 3 L/min on a continuous-flow setting weigh over 9 kg and require a trolley.
For all devices, if an oxygen-conserving device is used, the patient should be tested using that device during exertion, similar to what they would do in daily life, to ensure adequate oxygenation. A continuous-flow setting of 5 L/min and a pulse-flow setting of “5” may not deliver equivalent volumes of oxygen, despite direct marketing claims.
Patients depend on their DME company to deliver an adequate number of cylinders per week or month.
LOX costs are higher than costs for POCs or metal cylinders (103).
The Federal Aviation Administration stipulates which POCs are allowed for use during air travel (119).