please help with these ABG's

Published

82yo male on bipap FIO2 90% with diagnosis of pneumonia. o2 sats WNL.

ph 7.54

pco2 51

p02 64

hco3 43.6

BE 18.5

I am a relatively new ICU nurse and ABG's aren't my strong point. Charge RN and RT said ABG results were respiratory alkalosis due to anxiety and pt fighting bipap. If this is correct why is bicarb so elevated. What is your interpretation of these results?

Up Vote Up Vote ×
Specializes in Tele, Renal, ICU, CIU, ER, Home Health..

Hmmmm. This sounds like metabolic alkalosis to me. There is some respiratory compensation going on. Any other history? N/V, NG to suction? Without knowing more I couldn't say what is causing this, but I don't think Respiratory is the cause. Any ABG experts out there?

Up Vote Up Vote ×

thanks for your reply. a little more info--pt was getting lasix ivp, i think q 12 hours. BUN and creatinine were climbing but no history of renal dysfunction.

Up Vote Up Vote ×
Specializes in Critical Care, Pediatrics, Geriatrics.

Sounds like your pt was going into acute renal failure...probably why they were rataining HCO3. I would guess metablolic alkalosis as well. Lungs may have been trying to hold on to CO2 to correct. I would like to hear some more experienced opinions as well.

Up Vote Up Vote ×
Specializes in ICU.

Metabolic acidosis with respiratory compensation.

Up Vote Up Vote ×
Specializes in Med-Surg.

asoldierswife, I think in acute renal failure the patients are usually in metabolic acidosis and the bicarb levels are low. We frequently have to supplement bicarb with renal patients from what I've seen. But I believe that lack of kidney perfusion can cause it. (Trying to remember my patho class. LOL)

I agree that this patient looks more like a metabolic alkalosis. Given the fact the patient is on lasix, I wonder what his K levels are, as met. alk. is associated with hypokalemia sometimes. Low chloride levels from diuretic use can be a cause.

Up Vote Up Vote ×

K level was low and pt was experiencing muscle twitching, which I know is a symtom of met. alkalosis.

Thank you all for your input. I hadn't thought about kidneys being the problem.

I wonder why the experienced RT thought this was a respiratory problem?

Up Vote Up Vote ×
Specializes in ICU.

Look at the Nomogram for ABG's in the following text

http://umed.med.utah.edu/ms2/renal/Word%20files/i)%20Acid_Base%20Disorders.htm

image002.gif

Nomograms are absurdly simple to use and will give you a more accurate insight into what is happening than those silly up down arrows.

Use one for a while and it will not be too long before reading the gas will come more easily

Up Vote Up Vote ×
Specializes in ICU.

Here is a link to a classic Sigaard-Anderson chart unfortunately the rest of the site is not in English:p

674D8189-29D0-48B2-807D-A98F1DD9A1C1

http://www.der-tiefe-einblick.de/674D8189-29D0-48B2-807D-A98F1DD9A1C1

On the site you can enlarge this to make it more readable

Up Vote Up Vote ×
Specializes in Critical Care, Pediatrics, Geriatrics.
asoldierswife, I think in acute renal failure the patients are usually in metabolic acidosis and the bicarb levels are low. We frequently have to supplement bicarb with renal patients from what I've seen. But I believe that lack of kidney perfusion can cause it. (Trying to remember my patho class. LOL)

Thanks...I was questioning that but I am a novice at ABG interpretation as well.

Would the lasix compound the problem? With a high C02 level on 90% bipap...do you think this pt needs to be ventilated?

Up Vote Up Vote ×
Specializes in Tele, Renal, ICU, CIU, ER, Home Health..

Yep, I would guess that the lasix is the culpret. I'm wondering why he's getting lasix with a diagnosis of pneumonia. Anyway, this guy needs IV fluids and K+ replacement. Might want to check a magnesium level. Also watch his Rhythm while his electrolytes are so screwed up. Hats off to you for questioning the Nurse and RT. The doctor needs to be notified of these results! What a great learning experience for you!

Up Vote Up Vote ×
Specializes in Med-Surg.
Thanks...I was questioning that but I am a novice at ABG interpretation as well.

Would the lasix compound the problem? With a high C02 level on 90% bipap...do you think this pt needs to be ventilated?

I think definately one needs to look at the lasix as perhaps causing electrolyte imbalances which might have thrown this person into this condition.

I'm not sure about intubation as I am not sure when they decide to intubate, but the p02 of 64 is very worrisome and might warrent intubation. Again, I bow to the experts on this one.

Good questions and good learning experiences for us all.

Up Vote Up Vote ×
+ Add a Comment