+- Apnea Board Forum - CPAP | Sleep Apnea (https://www.apneaboard.com/forums)
+-- Forum: Public Area (https://www.apneaboard.com/forums/Forum-Public-Area)
+--- Forum: Main Apnea Board Forum (https://www.apneaboard.com/forums/Forum-Main-Apnea-Board-Forum)
+--- Thread: [Equipment] Fabrication of an Enhanced Expiratory Rebreathing Space (EERS) (/Thread-Equipment-Fabrication-of-an-Enhanced-Expiratory-Rebreathing-Space-EERS)
RE: Fabrication of an Enhanced Expiratory Rebreathing Space (EERS) - slowriter - 11-23-2019
(11-23-2019, 03:42 PM)slowriter Wrote:(11-23-2019, 03:34 PM)sherwoga Wrote: The very high leak rate surprised me for both nights. But I guess in hindsight, it shouldn't. Purposely putting a hole in the line (a vent) will likely be seen as a leak by the system. Does this mean that the pump is having to work harder and will using the EERS be hard on the pump? Also, does it mean that the pressures achieved at the mask are significantly lower than what is being reported? If so, higher pressures might be in order.
On this, I will just say I had no machine-reported leaks when I tried EERS.
I should clarify that what I mean to say is that my leaks did not change when I added EERS.
But I use a Bleep nasal-pillow-ish mask.
RE: Fabrication of an Enhanced Expiratory Rebreathing Space (EERS) - sherwoga - 11-23-2019
(11-23-2019, 03:42 PM)slowriter Wrote:My machine has a Mask Leak Test function. After seeing this post, I ran the test as follows:(11-23-2019, 03:34 PM)sherwoga Wrote: The very high leak rate surprised me for both nights. But I guess in hindsight, it shouldn't. Purposely putting a hole in the line (a vent) will likely be seen as a leak by the system. Does this mean that the pump is having to work harder and will using the EERS be hard on the pump? Also, does it mean that the pressures achieved at the mask are significantly lower than what is being reported? If so, higher pressures might be in order.
On this, I will just say I had no machine-reported leaks when I tried EERS.
- 1) Tested the supply hose as designed without my EERS - passed
- 2) Tested the supply hose with one section of C-A-F hose and whisper swivel valve in direction 1 - failed
- 3) Tested the supply hose with one section of C-A-F hose and whisper swivel valve in direction 2 (opposite) - failed
- 4) Tested the supply hose with one section of C-A-F hose and safety valve in direction 1 - failed big time
- 5) Tested the supply hose with one section of C-A-F hose and safety valve in direction 2 (opposite) - passed
In order for the EERS to be effective, it must create an un-swept volume of space in the supply line. It is logical then to conclude that absent the EERS, the entire supply line up to the mask has to be swept. Otherwise the premise of the EERS blows up. How can you create an un-swept volume from an un-swept volume? And not having a fully swept line means I've been re breathing my exhaust all along. If the entire line is swept absent the EERS, then there has to be an exit for the sweeping air. I tried to describe where I think (I did not prove this) that exit is in the last two pictures of Post #18 . Now I'm left with the question of how my CPAP can tell the difference between air escaping the supply line from the mask exit (absent the EERS) and air escaping the supply line at the Whisper Swivel Valve (with the EERS).
Fred did respond to my Post #18 and he was unconcerned about the high leak rate; however, I require more time and rumination to understand what he is saying.
I remain doubtful about what the EERS might be doing to the CPAP control algorithms (the functions internal to the machine that increase the air flow to create a desired pressure measured in the machine and not at the mask itself: there is no transducer at the mask). Does the high leak rate suggest that the machine's internal pressure measurement no longer reflects the same about the pressure at the mask? The answer to that question is probably academic and adequate experimentation can still lead to the best combination of Pressures (min and max), EPR setting, and EESR volume. Any other variables?
Advise from Fred included monitoring for the OAE's to see if they persist. He also continues to advise caution. I'm glad to have him on our side.
RE: Fabrication of an Enhanced Expiratory Rebreathing Space (EERS) - Sleeprider - 11-23-2019
(11-22-2019, 02:44 PM)sherwoga Wrote:Cubic centimeters are the same as cubic mL. Standard Corr-a-Flex is in 6-inch (15.24 cm) segments which has about 58 mL of dead space. (The volume of the tubing is V = Pi * r squared * length and 22 mm diameter tubing has about 3.8 mL/cm with 15 mm diameter tubing being about one-half (0.7) of that volume).(11-22-2019, 09:18 AM)sherwoga Wrote:(11-21-2019, 11:29 PM)Hydrangea Wrote: Color me clueless. Are trying to make yourself re-breathe your carbon dioxide?
The section of tubing that I am attempting to use to create "dead" volume (or re-breathing space) can be considered to be a cylinder of length 6 inch and radius 11 millimeters. The volume of a cylinder is given as
V = πr²l.
This works out to about 58 mL.
That should be 1.1 centimeters not 11 milliliters. Sorry!
RE: Fabrication of an Enhanced Expiratory Rebreathing Space (EERS) - Gideon - 11-23-2019
SR, you cannot have 'cubic' ml, though a cubic cm is a ml.
I've attached a modified picture for an EERS assembly. Hopefully, it will clarify it for some people.
[attachment=17415]
RE: Fabrication of an Enhanced Expiratory Rebreathing Space (EERS) - Sleeprider - 11-24-2019
(11-23-2019, 11:04 PM)bonjour Wrote: SR, you cannot have 'cubic' ml, though a cubic cm is a ml.
I'll have to start drinking from square glasses.
RE: Fabrication of an Enhanced Expiratory Rebreathing Space (EERS) - slowriter - 11-24-2019
On leaks, this paper notes the following:
Quote:The technique was highly leak intolerant, as leaks normally acceptable (20-30 L/ min) resulted in loss of breathing stability if the leak washed out the rebreathing space.
RE: Fabrication of an Enhanced Expiratory Rebreathing Space (EERS) - sherwoga - 11-24-2019
(11-23-2019, 10:57 PM)Sleeprider Wrote:I really messed this one up. I got in a hurry and referred to the radius as being 11 milliliters. Radius is a distance parameter and the units used should be units of distance. Milliliters is a unit of volume. This was just a series of brain farts (if you will forgive my vulgarity).(11-22-2019, 02:44 PM)sherwoga Wrote:Cubic centimeters are the same as cubic mL. Standard Corr-a-Flex is in 6-inch (15.24 cm) segments which has about 58 mL of dead space. (The volume of the tubing is V = Pi * r squared * length and 22 mm diameter tubing has about 3.8 mL/cm with 15 mm diameter tubing being about one-half (0.7) of that volume).(11-22-2019, 09:18 AM)sherwoga Wrote: The section of tubing that I am attempting to use to create "dead" volume (or re-breathing space) can be considered to be a cylinder of length 6 inch and radius 11 millimeters. The volume of a cylinder is given as
V = πr²l.
This works out to about 58 mL.
That should be 1.1 centimeters not 11 milliliters. Sorry!
I saw my error later and tried to correct it by changing the 11 milliliters to 1.1 centimeters (or cm). Further upon thinking about it, I realize I made all kinds of assumptions about the math that I guess I thought everybody would make. Trying to clarify that now will only create further confusion. Sleeprider has stated the math concisely and beyond apologizing for the confusion I created, I'm going to leave this alone.
The point is, the EERS introduces an un swept volume of air that is far smaller than the volume of a breath. Therefore, the amount of carbon dioxide that is re breathed when using a short section of tubing in an EERS is small, relatively speaking.
RE: Fabrication of an Enhanced Expiratory Rebreathing Space (EERS) - JoeyWallaby - 11-24-2019
Your leak rate with EERS isn't normal. These are my EERS charts with safety valve and whisper swivel II.
http://www.apneaboard.com/forums/Thread-Health-Interpreting-sleep-study-results-EERS-enhanced-expiratory-rebreathing-space?pid=318231#pid318231
http://www.apneaboard.com/forums/Thread-Health-Interpreting-sleep-study-results-EERS-enhanced-expiratory-rebreathing-space?pid=318950#pid318950
http://www.apneaboard.com/forums/Thread-Health-Interpreting-sleep-study-results-EERS-enhanced-expiratory-rebreathing-space?pid=319468#pid319468
http://www.apneaboard.com/forums/Thread-Health-Interpreting-sleep-study-results-EERS-enhanced-expiratory-rebreathing-space?pid=319904#pid319904
RE: Fabrication of an Enhanced Expiratory Rebreathing Space (EERS) - Gideon - 11-24-2019
Let's take a deep dive into leaks with EERS
Any leak before the EERS system is of (almost) no consequence. It cannot exceed the ability of the PAP machine to make up for it.
1. Remove the mask. It is ok to remove the short hose too. Assumption: no leaks exist in the short hose and the mask vent is completely blocked.
2. with the PAP running completely block the tube with your hand for at least 5 minutes. For our purposes this allows us to measure what the expected leakage is for the swivel with the exhaust port.
3: Mark this value on the leak chart. everything above this line will be unintended leakage. The medical documentation stated that the amount of rebreathing is impacted by mixing, turbulence and leaking so 'normal' leakage is OK. But the leakage above the expected leakage will impact the amount of air that is 'rebreathed".
To understand leaks with EERS we need to start here.
RE: Fabrication of an Enhanced Expiratory Rebreathing Space (EERS) - jaswilliams - 11-24-2019
My concern is you have not adequately blocked the mask vents. Connect a hose to your mask put the mask on block the end of the hose and exhale, no air should exit the mask, your exhale should be blocked and force the mask off your face.