Blood Gas 016

26 year old female with vomiting, diarrhoea and now confusion. Her confusion prevents an adequate history and no collateral history is available at this time. A venous gas is performed in resus...

For a basic approach to blood gas interpretation see here

1. What is the Acid-Base disturbance?

pH = 6.98 ∴ severe acidosis

Work out the cause of the acidosis:

• CO2 = 19 ∴ metabolic acidosis

Is there appropriate respiratory compensation or concomitant process?

• Expected CO2 = 1.5 x HCO3 + 8 = 14
• Actual CO2 = 19 ∴ concomitant respiratory acidosis

Work out the cause of the metabolic acidosis:

• Anion Gap = 140 - 111 - 4 = 25 = HAGMA

Is there another concomitant metabolic process?

• Delta Ratio = (AG - 12) / (24 - HCO3) = (25 - 12) / (24 - 4) = 0.65
• 0.65 = mixed HAGMA + NAGMA

Overall Acid-Base disturbance
Mixed HAGMA & NAGMA with associated Respiratory Acidosis

2. Are there any electrolyte issues?

Na (for Glc)

• Actual Na = mNa + (Glc - 5)/3 = 140 + (48 - 5)/3 = 154.3
• ∴ Relative hypernatraemia

K (for pH)

• Expected K = 5(7.4 - pH) + 5 = 5(7.4 - 6.98) + 5 = 7.1
• Actual K = 5.6 ∴ severe hypokalaemia

Ca (for alb)

• Neither Ca or Albumin reported

3. Are there any oxygenation issues?

This is a venous sample ​∴ unable to calculate

4. What is your overall impression?

This patient has a life threatening acidosis due HAGMA with concomitant NAGMA and respiratory acidosis with a relative hypernatraemia and severe hypokalaemia.

Given her age and her BSL, the most likely cause is:

1. HAGMA = DKA
2. NAGMA = Aggressive NaCl resuscitation or recovering DKA
3. Respiratory Acidosis = Getting tired from having to resp compensate