Acidosis and alkalosis

[direw0lf, BSN]

I was trying to prepare a little for patho and medsurg next semester and had a question about this please... wouldn't respiratory and metabolic acidosis always coexist? As well as respiratory and metabolic alkalosis always coexist?

Almost afraid to post this in case it's way too stupid..

[dan1100rt]

It's not stupid - ABG interpretation takes some practice.

Acidosis is either too much acid or not enough base / alkalosis is too much base or not enough acid. The acidosis or alkalosis in question will have a source which would be respiratory or metabolic (i.e. no, they don't coexist).

For example, respiratory acidosis is a result of shallow breathing (from some other medical problem) which traps too much CO2 in the lungs and decreases the overall pH. If the patient's kidneys are healthy, you'll see their bicarb level go up to fight to acidosis - this is compensation.

Metabolic acidosis is when their kidneys aren't healthy and don't make enough bicarb so their pH goes down. In that case the patient often involuntarily breathes rapidly to blow off extra CO2 and raise their pH - another form of compensation.

Respiratory alkalosis can come from tachypnea (breathing too fast), thereby blowing off too much CO2 and raising the pH.

Metabolic alkalosis is from too much bicarb (usually iatrogenic) or loss of acid (e.g. from emesis or loss from too much gastric suctioning).

Here is a guide to ABG interpretation:

http://www.mydsn.net/docs-tools/NRS440/McClintock/ABGInterpretationPacket.pdf

[direw0lf, BSN]

Thank you dan1100rt! That site really was great. I found out where I was getting confused (picking out lungs from kidneys/respiratory from metabolic) and those practice questions helped reinforce.