RE: Requesting Advice for Elderly Mother
(10-22-2022, 06:06 PM)Sleeprider Wrote: There is considerable dilution of oxygen in any positive air pressure circuit and this lowers the fraction of inspired oxygen (fiO2) when PAP is in use. The presence of leaks makes this dilution much greater, making it harder to raise FiO2.
So we finally were able to get a good fit last night, the machine detected no leak, and I watched as my mom's SpO2 dropped quickly and suddenly into the 70's after about an hour (no leak at this time). I pulled the mask and placed her cannula on her, and she quickly recovered. Any idea what could be happening? We're being told there's nothing wrong with the BiPAP or concentrator, but it sure seems like the BiPAP may be set up incorrectly.
RE: Requesting Advice for Elderly Mother
The bleed rate into the CPAP circuit is too low. Read the wiki and discuss the problem with her doctor. The most obvious method of establishing the bleed rate needed is to titrate oxygen bleed while observing SpO2 and using a sufficient bleed rate of O2 to maintain the patient's saturation. "Titration" is nothing more than trial and observation, whether it be with CPAP pressures or oxygen bleeds.
http://www.apneaboard.com/wiki/index.php..._with_CPAP
RE: Requesting Advice for Elderly Mother
For several years, we had been putting the oxygen bleed adapter directly into the machine as shown in the picture. During a recent hospitalization, the respiratory staff placed the oxygen bleed adapter at the end of the hose closest to the patient. It helped considerably, though I don't understand why. This may be an experiment worth trying.
RE: Requesting Advice for Elderly Mother
(10-25-2022, 11:24 AM)clownbell Wrote: For several years, we had been putting the oxygen bleed adapter directly into the machine as shown in the picture. During a recent hospitalization, the respiratory staff placed the oxygen bleed adapter at the end of the hose closest to the patient. It helped considerably, though I don't understand why. This may be an experiment worth trying.
I tried this and didn't notice a major difference, but the leakage was probably too substantial. May be worth another try. Thank you all for the suggestions and comments. Tech is returning today with another machine, I don't have high hopes after six nights of no sleep and monitoring oxygen. Mask liners have helped get a more consistent fit, but didn't prevent eventual drop in SpO2, even with zero leak. The concentrator is clearly not putting out enough oxygen.
10-25-2022, 06:01 PM
(This post was last modified: 10-25-2022, 06:13 PM by MattInMD.)
RE: Requesting Advice for Elderly Mother
So the technician came. Five liters from the concentrator maxed out at 32% FiO2. We also tested from an oxygen tank and it still couldn't keep her pulse ox up. So I guess we need a larger concentrator (or a 2nd one). But something the tech kept saying is she changed all the settings to help my mom as much as possible, including upping the PEEP. I'm new to all this, but I did some searching on PEEP, and it sounds like higher settings can be counterproductive to oxygenation. Is this something I should bring up to the doctor, that the tech isn't following the script he wrote? It's still not making sense to me that a woman maintaining 94-96% SpO2 on 2 liters of oxygen is dropping into the 70's at five liters while on the BiPAP with a low leak rate.
RE: Requesting Advice for Elderly Mother
PEEP helps to recruit lung volume and is commonly used to increase oxygenation. The need for a much higher oxygen bleed is something I have already repeatedly discussed. If FiO2 at 32% does not maintain your mother's SpO2 then a second oxygen generator may be needed, and is likely a good idea just in case one fails. With a canula you can get FiO2 to very high levels as there is no dilution of the oxygen, especially if you approximate the respiratory minute vent. Leaks in the circuit make it very difficult to achieve higher FiO2. If your mom can tolerate a nasal pillow interface, you can generally achieve much higher FiO2 with the same oxygen bleed, and leaks are easier to prevent due to the very small seal area on the nares. The Resmed Airfit P10 is the most minimal mask on the market. If she opens her mouth, then that won't work.
The doctor needs to know that this patient needs a clinical titration for SpO2. The technician did exactly what I suggested earlier to titrate thhe oxygen bleed, and was unable to maintain SpO2 with maximum generator output. These results are useful and essential for him to know to take the next step. This is not a tech doing something contrary to doctor's orders, this was someone knowledgeable on matters of how to titrate a patient. The results show she is in need of a higher level of assistance. What is the altitude where your mom lives? Does she use multiple pillows that might cause chin-tucking that obstructs her airway? Positional apnea is a suspect if she is able to maintain SpO2 while awake and on the respirator, but experiences severe episodes of desaturation once sleeping.
RE: Requesting Advice for Elderly Mother
I thought I'd provide an update. There was an immediate improvement in saturation rate the first night with the new Astral. A few days later, I heard from the pulmonologist's office who was asking if I'd made changes to the original Astral. I told them I couldn't have since everything was locked, but I watched the technician make changes. Apparently when they looked over the machine, they noticed settings that were dramatically different from what was prescribed. Either the technician set it up wrong, or made changes that were clearly not working in my mom's favor. The pulmonologist said they've never had a similar situation. I can't say the new vent is the entire reason for the improved saturation rates, we also started getting a more consistent mask seal, but even at zero leak we couldn't keep her in the 90's on the original vent. She's now averaging overnight saturation of 95-96% at 3.5 liters according to her Wellue Checkme Pro.
Thank you to everyone who chimed in!
