Does Oxygen count in the pressure?

Hello, this may sound odd but does the Oxygen count in the Cpap pressure setting? When I had my study for the setting up of my Cpap I was told they used a setting of 10. But when I got the machine it was set at 8 and to set my Oxygen generator to 2. So does that count for the 10? I seem to be doing great at the 8 so don't see any reason to change but would like to know. I don't have to see my Dr. for 4 months so thought I would ask here.
Thanks!
Don

N6CRV wrote:Hello, this may sound odd but does the Oxygen count in the Cpap pressure setting? When I had my study for the setting up of my Cpap I was told they used a setting of 10. But when I got the machine it was set at 8 and to set my Oxygen generator to 2. So does that count for the 10? I seem to be doing great at the 8 so don't see any reason to change but would like to know. I don't have to see my Dr. for 4 months so thought I would ask here.
Thanks!
Don

Good question, I have been thinking this one through as I have an oxygen concentrator I intend doing some tests with.
If a cpap is set at 8 and you then connect an oxygen concentrator that can deliver 2 cmH2o of pressure it is reasonable to
assume the 8 + 2 get added & result in 10 cmH2o.

So my 1st question is - do you have your oxygen concentrator attached ? - while that is attached are you getting the 'good results' ?.



In addition, this configuration brings to mind all the following questions ...

1) How do we convert litres per min flow from an oxygen concentrator (mine is rated 1-5) into cmH20 at the mask ?

2) What stops the cpap pressure (say 8 cmH2o) from pushing back into the oxygen concentrator if it is only delivering 2 cmH2o ?

3) If the cpap thinks it id delivering 8, but the O2 machines adds 2, then does that mean the statistics from the cpap will be confused ?


My own guesses at the questions are

1 - don't know
2 - am assuming the O2 machine can sustain the delivered rate/pressure due to how the pumping works
3 - the cpap will think 8 cmH2o is doing the job that in reality is being done by 10 cmH20, that will confuse an Auto, but the AHI is what counts & if that is good then that is what is needed

Nope.
Oxygen is measured in Liters (flow rate)......XPAP pressure is measured in "cm. of H2O" (how far it will push a column of water)


Den

Hello, the line from the Oxygen Concentrator is hooked into an adapter right at the outlet from the Remstar. All my numbers look good so guess it must be working.
Thanks!
Don

N6CRV wrote:Hello, the line from the Oxygen Concentrator is hooked into an adapter right at the outlet from the Remstar. All my numbers look good so guess it must be working.
Thanks!
Don

On thinking about it (out loud ), I believe it works this way ...

Firstly as you have indicated you use a connector like this http://www.cpapsupplyusa.com/Oxygen-Sup ... 642-1.aspx at the machine end of the hose (this is what I have set up myself). I used to use a UMFF mask which allowed O2 to be piped directly into the mask but it adds tubes that get in the way & piping in the O2 at the machine end is the easier thing to do.

Secondly, when you set the O2 machine you do so by adjusting a flow in litres/min & that is what the doc writes on the prescription (i.e. Supplemental O2 at 2 l/m). So having dialed up the recommended l/m of O2 the concentrator delivers that flow & this is indicated at the front of the O2 machine. It will do this against any pressure in the air line as long as the indicator on the front of the O2 machine says the flow out is at the adjusted setting.

The pressure at the exit port of the cpap is going to reflect the cpap delivered pressure plus any other pressure present such as from the O2 machine (the internal pressure sensor in the cpap will read the pressure at the exit port & adjust the cpap blower to deliver a pressure the machine is currently set for (either from the cpap mode pressure setting or the current pressure calculated from an Auto algorithm).

So all works as it should. The cpap delivers its pressure & the O2 machine delivers its flow.

DSM

I would imagine that the flow of oxygen is set up so that if there is increased pressure on the system, that the flow regulator would adjust accordingly to keep the flow at 2 liters / minute (The pressure of an oxygen bottle and a oxygen generator far exceeds whatever a CPAP unit could produce). The CPAP machine if it detected a higher pressure from the oxygen system, it will regulate to lower the pressure of itself so that it maintains a steady pressure.

Both systems would reach a level of where the pressure and flow would remain constant.

Add breathing to the system and you would have fluctuations to maintain the status quo of the system.

The pressure of the oxygen flowing at 2 L per minute cannot be converted easily to a pressure unless you have a lot of information about the system.

Linus wrote:I would imagine that the flow of oxygen is set up so that if there is increased pressure on the system, that the flow regulator would adjust accordingly to keep the flow at 2 liters / minute (The pressure of an oxygen bottle and a oxygen generator far exceeds whatever a CPAP unit could produce). The CPAP machine if it detected a higher pressure from the oxygen system, it will regulate to lower the pressure of itself so that it maintains a steady pressure.

Both systems would reach a level of where the pressure and flow would remain constant.

Add breathing to the system and you would have fluctuations to maintain the status quo of the system.

The pressure of the oxygen flowing at 2 L per minute cannot be converted easily to a pressure unless you have a lot of information about the system.

Linus

Yup, I agree with all that
But - I did need to think about it all 1st

The flow delivery mechanism on the front of the O2 machine is a steel ball in a glass tube & the way it works, is a pretty accurate way of observing flow at the desired rate. Also I came across some posts of SAG's in another thread nearby where he comments on nebulizers & oxygen cylinders & oxygen concentrators - he mentions the pressures they can reach.

DSM

DSM

N6CRV wrote:Hello, this may sound odd but does the Oxygen count in the Cpap pressure setting? When I had my study for the setting up of my Cpap I was told they used a setting of 10. But when I got the machine it was set at 8 and to set my Oxygen generator to 2. So does that count for the 10? I seem to be doing great at the 8 so don't see any reason to change but would like to know. I don't have to see my Dr. for 4 months so thought I would ask here.
Thanks!
Don

I would suggest you get a copy of your prescription and ask questions to make sure everything was set up in accord with it.

jeff

Just remember that the pressure is at the guage not at the end of the tubing. This would be similar to water or anything else that flows through a tube or pipe. Their is going to be friction loss so the pressure at the end of the tubing will be less than at the beginning to a degree unless it is an extremely short run.

I have seen people at home with oxygen concentrators who have tubing long enough for them to walk completely around the house and to the neighbors house. They complain of having trouble breathing and call us we put them on our oxygen at the same rate they are on at home and their oxygen sats jump right up and they feel much better. I have had to shorten a few od these tubes for people.

Gerryk wrote:Just remember that the pressure is at the guage not at the end of the tubing. This would be similar to water or anything else that flows through a tube or pipe. Their is going to be friction loss so the pressure at the end of the tubing will be less than at the beginning to a degree unless it is an extremely short run.

I have seen people at home with oxygen concentrators who have tubing long enough for them to walk completely around the house and to the neighbors house. They complain of having trouble breathing and call us we put them on our oxygen at the same rate they are on at home and their oxygen sats jump right up and they feel much better. I have had to shorten a few od these tubes for people.

Gerry

You betcha - the tube that came with the Respironics concentrator I am playing with, is sooo long it really could reach the house next door (I think )
Certainly I could put the O2 machine in the next room (in fact that is the only way wife will tolerate it - it is just a tad noisy )

But, also remember that the flow indicator at the O2 machine is saying what the flow is & that is how O2 is dispensed - by flow rate. So if it says 2 lpm (liters per minute) then the losses in the tube are already taken into account. Restated, if the O2 machine is sending out 2 lpm, then no matter how long the hose is (within some reason) the delivery at the far end will be that same 2 lpm.

DSM

Doug your right on. It's late I am usually in bed by now and I keep thinking strictly water pressure. If you have a hose that long I hope you check it for leaks. Coil it up and put it in some water to check for leaks. With it being stepped on they do get pin holes and cracks. They are a great chew toy for cats too.

Gerry