Viva 2

A 70 year old woman has been referred to the ICU from ED. She has presented with confusion and decreased mobility over the last two weeks. She is a poor historian and lives alone.

On your assessment, this elderly lady has the following vital signs:

  • GCS 13 (E3 V4 M6)
  • BP 90/35 
  • HR 35
  • RR 10
  • Temp 34.5 C
  • SpO2 92% on 4L NP  

This is her ECG:

ECG myxoedema coma

What are the possible causes of this presentation?

(This is not a real CICM viva)

That's an ECG from LITFL, "the admission ECG of a 79-year old man who was referred to ICU with coma, hypothermia, severe bradycardia and hypotension refractory to inotropes"

The candidate should systematically go through a list of differentials, which may include:

  • MI (right sided infarct)
  • Sepsis with hypothermia
  • Beta blocker or calcium channel blocker overdose
  • Cholinergic agent toxicity, eg. organophosphates
  • Opiate overdose
  • Myocarditis
  • Hypothyroidism
  • Hypoadrenalism
  • Environmental exposure (i.e. the hypothermia is the main cause of everything)
What investigations would you like to send?
  • ABG
  • Biochemistry panel
  • Anything would be appropriate here, but specifically, you want them to ask for TFTs
The TSH is over one hundred times the upper limit of normal. How do you interpret this?
  • Severe hypothyroidism or myxoedema coma
  • The terms are essentially interchangeable
What could be the cause of this?

Drugs:

General anaesthetics

Lithium

Amiodarone

Barbiturates

Phenothiazines

Phenytoin

Rifampicin

Opiates

Weird causes

Consumption of raw bok choy

Illness

  • Surgery or trauma
  • Burns
  • Sepsis
  • Stroke
  • Congestive heart failure
  • GI bleeding
  • Hypoglycaemia
  • Acidosis
  • Hypoxia or hypercapnea
What are the other physical examination features of severe hypothyroidism?
  • Cardinal features
    • Cardiovascular collapse, shock
    • Hypothermia
    • Decreased level of consciousness
  • Associated examination findings
    • A "puffy" face
    • Macroglossia
    • Periorbital oedema
    • Missing central eyebrows
    • Coarse, sparse hair
    • Non-pitting oedema
    • Goitre
What are the biochemical features of severe hypothyroidism?
  • Hypothyroidism
  • Hypercapnea
  • Hypoxia
  • Hyponatremia
  • Hyposmolarity
  • Elevated protein levels on LP
  • High serum cholesterol
What ECG findings do you normally expect with this condition?
  • Prolonged PR interval
  • Decreased QRS voltages, especially in the limb leads
  • Prolonged QT
  • Bradycardia
  • Deep T-wave inversions
What is the origin of her haemodynamic instability?
  • Heart failure with poor cardiac output due to:
    • Poor contractility
    • Slow rate
    • Decreased catecholamine responsiveness due to hypothermia
  • Dehydration (confused, therefore likely less access to food and water)
  • Pericardial effusion and cardiac tamponade can often be associated with
  • MI is not ruled out
What specific management would you offer?
  • Replace thyroid hormone - preferably IV
    • loading dose is 300-400μcg
    • a rising body temperature and normalising cardiovascular parameters alert you to the success of your management strategy
  • Replace corticosteroids - there is usually a concomitant adrenal insufficiency. One would use a "stress dose".
  • Correct the sodium: this is usually a hypervolemic hyponatremia which resembles that of CCF (in fact, it is because of exactly the same mechanism: poor cardiovascular performance leads to ADH and aldosterone driven retention of water and sodium, with a resulting hypervolemic hyponatremia. Because the patient is usually obtunded, one is obliged to correct a particularly low sodium with hypertonic saline, being careful not to demyelinate the CNS.
  • Good solid supportive management:
    • Establish an airway if this is needed
    • Maintain normoxia and normocapnea with the ventilator
    • Maintain normotension to support organ system perfusion, with a catecholamine infusion
    • Correct the Na+ deficit - consider using water restriction alone.
    • Correct hypoglycaemia
    • Correct hypothermia with warming blanket

Disclaimer: the viva stem above may be an original CICM stem, acquired from their publicly available past papers. Or, perhaps it is a slightly altered version of the original CICM stem. Or, it is a completely original viva stem, concocted by the monstrously amoral author of Deranged Physiology for nothing more than his own personal amusement. In either case, because the college do not make the main viva text or marking criteria available, almost everything here has been confabulated. It might sound like a plausible viva and it could be used for the purpose of practice, but all should be aware that it does not represent the "true" canonical CICM viva station.