This opinion piece was written and submitted by COPD community member, Tony St. Amant of Chico, California.
The other day I received an email announcing a portable oxygen concentrator (POC) weighing less than two pounds with a battery life of three hours, and even longer with supplemental batteries. Wow! A two pound oxygen source that could operate for three hours or more! Absolutely dazzling to anyone who has been tethered by supplemental oxygen for any length of time–except, the devil is in the details.
I scanned the manufacturer’s product webpage to find out how much oxygen this little dynamo can provide, but it’s not there. There is only an indirect reference to a “2 pulse setting.” What in heaven’s name does that mean? Is it a shadowy implication that this little baby can output 2 liters per minute (LPM)? If not, what does the “2” mean? I need to know, so I start digging through the support literature. The cut sheet is no help. It contains substantially the same info as the web page.
Finally, I find the Patient Manual—you know, the document you normally read after the unit is bought, paid for, and delivered. And there it is, on page 30 of the 40 page manual, almost an answer. Each pulse delivers 17.25 milliliters (ml) ± 10%. But, unlike most pulse dose specifications I’ve seen over the years, this one doesn’t specify a respiration rate. Will it deliver that pulse dose at 10 breaths a minute, 15, 20, more? There can be a world of difference in the unit’s therapeutic value.
So let’s take a look at what I will call best case oxygen output. Let’s assume the machine is operating at the upper boundary of output: 17.25ml + 10%. That would be 18.975ml per pulse. If it will provide that output at a fairly normal resting rate of 15 breaths per minute, its total output would be about 285ml per minute or about .3 liters per minute. If it will provide that output at a somewhat elevated respiration rate of 20 breaths per minute, its total output would be about 380ml per minute or about .38 liters per minute. But who knows? That information is not disclosed. And what’s the real value of a two-pound $2,000+ POC that might be insufficient under mild exertion?
Of course, it’s not as simple as that. A person who has a prescription for 2 LPM continuous doesn’t actually inhale two liters of output from any oxygen source. The actual amount inhaled is dependent on respiration rate and other factors. But there is no industry or government standard for comparing pulse to continuous flows. Additionally, a POC that delivers a nominal continuous flow of 2 LPM doesn’t actually deliver 2 LPM of oxygen. For POCs, oxygen is normally somewhere between 87 and 95 percent of the flow. Therefore, the oxygen delivered at 2 LPM continuous flow is typically between 1.74 and 1.9 LPM.
So if you have an oxygen prescription for as little as 2 LPM, will this hyped up pulse-flow mini-POC meet that requirement? It’s not clear at all that it will, nor is the real pulse flow equivalency clear for any other POC. And even if the POC will deliver 2 LPM of oxygen at rest, will it deliver it at an elevated respiration rate during physical activity? The only information available to the potential POC buyer is that published by each manufacturer, with no assurance that the basis for the information is consistent between manufacturers.
If “buyer beware” ever applied to any market, it applies to the POC market. If you’re shopping for a POC, good luck. Please hope with me that the U.S. Food and Drug Administration or the industry will come up with standards that will help individuals with COPD accurately match their needs with POC oxygen output.
-Tony St. Amant