any guess about low pCO2?

slcpicu · Oct 25, 2008

my first guess would be that although the resp are less than 20 prior to intubation the pt is doing some neuro protection of his own by breathing down his CO2 and therefore decreasing his CBF and decreasing some of the probable increased ICP due to possible swelling. After doing a quick search I did find this information "Hyperammonemia with respiratory alkalosis is caused by a urea cycle defect". Without other information it make this alittle more difficult to guess at. let us know.

allnurses Guide · Oct 25, 2008

What tidal volumes?

slcpicu · Oct 26, 2008

Hyperammonemia with respiratory alkalosis is caused by a urea cycle defect". After further research DISREGARD this, it is only pertaining to the neonate. I spoke with our fellow and cerebral edema and what I had said about doing some brain protection on his own is most probable cause of this pts hypocarbia.

babynurselsa, RN · Oct 26, 2008

What are your bicarb abd BE? You are dealing with a metabolic problem that affects the respiratory, versus a respiratory problem that affects the metabolic system.

slcpicu · Oct 26, 2008

Granted this is a metabolic problem being liver fx and increased ammonia. With the information provided, I can tell you what the bicarb is and calculating what the gas should be if there is no metabolic component it would be 7.52. So, with the information provided, the pts bicarb is probably slightly elevated because the gas is 7.55 (if you want to know how I got that let me know, otherwise I will assume you know) Most pts that have some neuro component will self compensate (to decreased CO2 therefore decreasing CBF and ICP assuming this is what is happening) esp if they are post TBI or even a coma with maintained resp drive.

So, we can get the information that you want to know from the information provided.

registeredin06 · Oct 26, 2008

Yup...Tidal volumes. We had intubated at 6 p.m. and, honestly, I overlooked his TV. Next day, TV 1000's. Funny how sometimes the simple stuff flies over your head. Thanks for everyone's input!! Nice critical thinking!

allnurses Guide · Oct 27, 2008

Well, it occurred to me because if your RR hasn't changed, but your CO2 is going down, the minute ventilation must have increased - so I'd look at Vt. Thanks for updating us!

registeredin06 · Nov 5, 2008

A little update...

I was off work a week and when I returned the pt. had an additional diagnosis of urea cyle disorder. Apparently only a handful of adults have had this diagnosis. Treatment is IV arginine and sodium benzoate, which is the only way we were able to start decreasing ammonia level, with no previous results using lactulose per NGT and enemas, CRRT, and dialysis. Unfortunately, we may not have found this soon enough

Only time will tell.

registeredin06 · Nov 5, 2008

Oops, I almost forgot...nice work slcpicu! I researched this when you first posted, but I too disregarded it because I found it to be a congenital issue. The case is pretty interesting and I'd like to share more, but I hate to get too detailed online...we all know HIPPA.

Dinith88 · Nov 14, 2008

...With the information provided, I can tell you what the bicarb is and calculating what the gas should be if there is no metabolic component it would be 7.52. (if you want to know how I got that let me know, otherwise I will assume you know)...
.

??? :smokin:

slcpicu · Nov 17, 2008

Thanks Registered. Wow I ended up being kinda right to begin with. LOL sometimes it's better to be lucky than good. This is a very interesting case. Any updates on outcome?

Dinith 88 did you have a question?