Can anyone help me understand this ABG!

[MedicalMentalist]

I have been trying to understand ABGs all night. I stumbled upon this website (altitude.org | Calculators | Arterial Blood Gas Calculator) and it calculates everything you could possibly want in an ABG. However, I have got this ABG to interpret and I just don't get it, and I can't get the ABG calculator to agree with the numbers!
PaO2 13kPa (100mmHg)
PaCo2 11.6kPa (80mmHg)
H+ 20 (pH 7.61)
HCO3 19mmol/l

Can anyone help me please!!

[Touche]

Your numbers don't fit. Given that HCO3 we'd expect an acidosis, given that PaCO2 we'd expect an acidosis... but we have an alkalosis... that's why I assume these interpreters are throwing a fit. Have a look at where you got the numbers from again and make sure you have them right.

[csx20032003]

That is

[rustyblueyez]

The pH could be thown off by temperature variation in the sample.
What should be a mixed metabolic/respiratory acidosis could be misinterpreted by the machine.
Also were you given an Anion Gap? It may be possible that there is another base counteracting your acidosis.
good luck

[Gizmo says -]

well done RustyBloo

[superdoc1]

The pH could be thown off by temperature variation in the sample.
good luck

Thats an idea but pH shouldn't vary that much

[rustyblueyez]

I think you're right superdoc1, there is a better explanation.
The most common cause of metabolic alkalosis is dehydration, suppose this patient is severely dehydrated: high pH, bicarb derangement, this might lead to loss of conciousness and subsequent ventilatory failure explaining the rising PaCO2.
You would expect to see this lower the pH but it may be a new onset i which case time would tell.

[superdoc1]

I think you're right superdoc1, there is a better explanation.
The most common cause of metabolic alkalosis is dehydration, suppose this patient is severely dehydrated: high pH, bicarb derangement, this might lead to loss of conciousness and subsequent ventilatory failure explaining the rising PaCO2.
You would expect to see this lower the pH but it may be a new onset i which case time would tell.

Indeed. pH in this instance will mostly be affected by the presence of whatever bronsted acids or bases are present (i.e bicarbonate). The high pH here could be as a result of the ''bicarb derangement'', rather than occuring with it. Also I found this webpage which might be useful:
Respiratpry Physiology: Acid-Base Phsyiology

[MedicalMentalist]

Thanks for all your advice guys - I emailed the guy who runs the ABG website that I was talking about, and he sent me a link to a totally amazing Arterial Blood Gas Interpreter. He also explained that it is mathematically impossible to have the derangement that my ABG showed, because CO2 H+ and HCO3 are inextricably linked.

[lindasegesvari]

One way of doing it…

Respiratory Acidosis if the PACo2 increased
Respiratory Alkalosis if the PaCo2 decreased
Metabolic Acidosis if the HCO3 in plasma decreased
Metabolic Alkalosis if the HCO3 in plasma increased

Or check:
If B.E is out of normal limit (-2;2) Metabolic
If PCo2 is not within normal limit is Respiratory
As well as if PH is high it is Alkalosis if too low Acidosis (7.35-7.45)

There is Type 1 and Type 2 Resp. Faliure,

Type 1 is when O2 Level below 8 (Hypoxemic)
Type 2 when there is too much CO2 (patient can not get ride of it) ( Hypercapnia)

Linda segesvari