As prepared by Chris Nickson, here are the practice written questions from this week’s CICM Second Part exam practice session at The Alfred ICU, with recommended reading from Lifeinthefastlane.com’s Critical Care Compendium and other FOAM sources:
a) The following laboratory results are obtained from a venous blood sample:
- What is the most likely cause? (10%)
- What differences would you expect in a patient with hyperosmolar hyperglycaemic syndrome (HHS)? (30%)
b) The following laboratory results are also obtained from a venous blood sample:
- What is the most likely cause? Explain your reasoning. (30%)
- What other investigations would support your diagnosis. (30%)
The cause is an artefact due to venous sampling proximal to an IV infusion of 5% glucose.
5% glucose is 278 mmol/L, so will cause an elevated blood glucose measurement and dilute the other laboratory values.
Differences in the laboratory results that may seen in HHS include:
- apparent sodium may be normal or mildly low, but will be elevated when corrected for glucose (e.g. corrected Na = 0.3 x (measured Na + (glucose – 5.5))
- very high calculated and measured osmolarity (> 320mosmol/kg)
- Ca, K, and Mg levels may vary depending on the underlying precipitant of the HHS, hydration state, and renal dysfunction
- renal dysfunction commonly present; often with a high urea to creatinine ratio due to dehydration
The diagnostic features of HHS are:
- serum osmolarity > 320mosmol/L
- serum glucose > 33mmol/L
- profound dehydration (elevated urea:creatinine ratio)
- no ketoacidosis
The diagnosis is multiple myeloma.
Key features are:
- low anion gap consistent with IgG myeloma (IgG is an “unmeasured” cationic molecule that lowers the anion gap). IgA myeloma may have an increased anion gap as IgA is anionic.
- mildly elevated phosphate
Other consistent findings would include:
- high uric acid and high LDH (due to cell turnover)
- high globulins
- plasma protein electrophoresis
- bone marrow aspirate
- serum free light chain analysis
- 24h protein urine analysis, urine protein electrophoresis, test for Bence-Jones proteins
Critically evaluate the use of therapeutic hypothermia in the management of severe traumatic brain injury.
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Describe your approach to the management of refractory hypoxaemia in intubated patients with severe acute respiratory distress syndrome (ARDS).
Provide justification(s) where appropriate.
Learn more here:
See this link on INTENSIVE for exam resources: