COPD

[jitushah]

Dear Doctors/Members,
My wife is using a Bi Level machine to enhance her breathing and to wash out her CO2 level in the blood during nights.At this moment the settings are 14 cmwc and 6 cmwc as IPAP and EPAP respectively.Recently we got her ABG done and found that her PCO2 has increased to 60%.
I wish to ask all those knowledeable people that to deal with the increased CO2 level,whether the EPAP setting should be reduced,to create more relative Vacuum for better washout of CO2, or increased.Please note that her lungs are weak as well lung capacity also low.She is on Oxygen therapy also and that is 1.5 LPM for about 15 Hrs. a day.
Thanks in advance.
Jitu

[Davy9]

The modality is called Bi-Pap and it is used at night. It works to augment spontaneous breathing by keeping the upper respiratory tract open with positive pressure and flushed out with a bias gas flow. They are attached to the patient usually with just a nasal mask but I believe a full face mask could be used.

The arterial CO2 level of 60% is incorrect. I believe you mean to say 60mmhg which is the partial pressure of CO2 in the blood. CO2 is the waste product gas from our metabolism. It needs to be eliminated from the body and a normal arterial level is around 40 mmhg. Yes, 60 is high. But, what is just as important to know is what was it before? How much has it changed and how quickly did that change happen? If her blood acidity (pH) is in the range of normal then the CO2 change happened slowly. The change in CO2 level does need to be addressed.

You're assuming that the increase in CO2 is a consequence of the Bi-Pap therapy and/or can be treated and corrected with the Bi-Pap settings. That is possible but it also may not be correct. She could have something else causing the CO2 to rise either quickly or slowly (a pneumonia for example). Talk with your doctors and make certain that other causes have been considered.

I cannot tell you how to they might change the settings on the Bi-Pap. I would think they need to put her into a controlled setting (a sleep laboratory) and assess how she is interfacing with the device and whether any changes will work. There they can measure her exhaled CO2 levels and make other measures to help understand how the set-up is working for her.

As an aside note, I would think that someone with an arterial CO2 level of 60 mmhg would need oxygen supplementation for more than 15 hours per day. Ask her doctors if she is using her oxygen as they want her to.

I apologize if this sounds too complex. You have delved into the arena of blood gases and they are not an simple subject to explain in person let alone on a forum like this one. Hopefully you can find this information useful.

[jitushah]

Thank you sir for your quick response and throwing more light on the subject.I am wrong to say 60% CO2 level instead of 60mmHg partial prssure of CO2.Actually she suffered from Pneumonia for 2-3 times in last 5 years,her lungs are mechanically pressed due Scoliosis amd operations later for it.Her CO2 partial pressure level base is changed to about 45-50 mmHg for last 2-3 years.The increase has taken place over a period of may be 2 months.She is suffering from RA also and High BP.As she takes Hydroquinin for her RA,the Haemoglobin level remains about 11 (though she takes 1.5LPM Oxygen).May be the Bi-PAP does not help to that extent now as it used to be.I shall ask her Doctor whether more Oxygenation would help as suggested by you.After checking all the points raised/suggested by you and actions taken,I wish to know how the Bi-PAP settings are decided theoratically and clinically.
Sir,if you dont mind,please let me know your true name and phone number.
Thank you again.
Jitu

[Davy9]

From your description I believe she suffers from a combination of obstructive and restrictive lung disease. Her recent change in CO2 levels could be a worsening of her status. I assume that she has done pulmonary function testing in the past and possibly a ventilation to perfusion scan of her lungs. If so they can repeat those studies now to determine what, if anything, has changed. Given this change in her ability to clear CO2 (ventilate) her oxygen therapy should be reviewed as you discussed.

The Bi-Pap machines have their purposes and their limitations. She may have progressed beyond their ability to provide adequate support. Again that needs to be studied. It is possible that she may need to have more aggressive support. Night time mechanical ventilation can be done via mask or by having a tracheostomy (an access portal through the front of the neck) done. I have also seen where negative external pressure mechanical ventilators have worked in such instances. These would be things like the old iron lungs only in more modern forms (but, you still can get iron lungs). Of course any of these would be used just at night. She is more compromised while supine and we all tend to slow ventilation down while we sleep.

To summarize her pulmonary function needs to be re-evaluated and her night time support system reassessed and modified as required. Getting into any particulars now would only serve to confuse things. Your doctors are your best source of answers. I can help you better understand the situation but cannot direct anything from here or even over the phone.