OK. Now, there are a couple of caveats to this week's solve.
1. That wasn't a particularly difficult blood gas. You need to be able to work through this level at a minimum for the exam. 2. The answer below is written without a calculator. So most of the calculations are generally accurate (i.e. close estimations) 3. You won't get a question like this in the real exam, that is a "interpret this ABG to it's fullest extent". BUT, when you see an ABG you should have a systematic approach to both interpreting it, and to inferring the necessary medical facts from it. That's what this week's exercise is designed to test.
So, see how your answer compares. Questions, comments etc via the VSG please.
1. ACID-BASE BALANCE
critical acidaemia critical hypocarbia critically low bicarbonate expect CO2 = 8 + 1.5 x 3.1 = 12.5 .: diagnose appropriate resp compensation ANION GAP = 126 – 93 = 33 HIGH DELTA RATIO = (33 – 12)/(24 – 3) = 21/21 = 1.0 .: Dx Isolated RAGMA
Therefore diagnose RAGMA with appropriate respiratory compensation.
2. Aa GRADIENT
FiO2 = .4 .: FiO2 = 300mmHg Aa grad = 300 – 1.25 X 13 – 260 = 300 – 16 – 260 = 24mmHg Expect for an 11yo = 6-7mmHg. .: this is slightly raised in the context of critical illness and is inconsistent with a presentation of asthma
Moderate hyponatraemia Correct for glucose = 126 + (31 – 5)/3 = 134mmol/L Critical hypokalaemia – danger of arrhythmia Correct for pH K+ should equal 5 + 5x0.5 = 7.5mmol/L .: this patient has a life threatening hypokalaemia Mild hypochloraemia Electrical equilibration for NAGMA Normal renal indices Hyperlactataemia Possible type A – dehydration Type B1 – intercurrent sepsis Type B2 – salbutamol use Critical hyperglycaemia
Therefore: RAGMA plus hyperglycaemia suggests new Dx type I diabetes This patient is critically ill Issues: