Wisp stats

[mousetrap]

Just browsing the handbook which came with the Wisp mask as I was trying to see if there was mention of the intentional leak rate for this mask. I can't seem to find that information.

Does anyone know the stats?

Also, as you may be aware the Wisp comes with three size nasal masks. There is mention in the booklet of "Deadspace Volume" as follows:

P 37mL
S/M 49mL
L 73mL

Can someone explain what these figures refer to please?

[RonWessels]

Assuming you put the CPAP air supply tube directly into your nose, there would be no "dead space". However, that's not what this mask does. The air hose connects to a plastic "bubble" that then seals to your nose. This volume of the plastic "bubble" is what I suspect they call the "dead space".

My brief usage of Google-fu could not find a User Manual for the Wisp mask. Furthermore, it appears that Respironics has not updated their intentional mask leak document with data for the Wisp. So, unless it is mentioned in your manual, the only way to get that information would be to call Respironics directly and ask them.

[zonk]

with absence of any info from Respironcis, I suspect the Wisp vents leak rate is the same as True Blue and EasyLife nasal masks
@10 .... both 26 L/min http://www.healthcare.philips.com/asset....111027.pdf

[mousetrap]

Thanks guys for your replies

[RonWessels]

Well OK, if you are willing to go with a guess based on similarity. I wouldn't be too surprised if it were off by as much as 3 L/min, though!!

[Roelof]

The Wisp has a "System One resistance" rating of 1, the same as the TrueBlue, Comfortgel Blue or the Optilife, so the leak rate should be similar. But yes, that leaves a few liters variation.

As to dead space: that is the volume of air in a mask that is not replaced by the airflow from the cpap between breaths. When you exhale, the air goes out through the vent but the last bit of air stays in the mask and is inhaled again the next cycle followed by a huge volume of fresh air from the cpap machine.

If you had a deadspace running into liters, you would exhale into the mask and inhale the same air again in the next cycle, slowly increasing the carbon dioxide level and decreasing oxygen. A dead volume of a few mililiters is completely insignificant compared to the volume of air your lungs replace each breath so for cpap masks it does not matter. For deepsea diving equipment this stuff is vital however.

[Lucky7]

So, with less deadspace there is less chance of CO2 rebreathing?

The RT at the DME seems obsessed by this.