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Emma 17yo is found unconscious
Urine is positive for amphetamines and cannabinoids
Her urine osmolarity is high, serum osmolarity is low
ABG shows metabolic & resp acidosis
Bonus 500
100

What are some causes of altered mental state?

Differential diagnoses for someone with altered consciousness?

  • Hypovolaemia
  • Hypoxia
  • Acidosis
  • Hyper and hypokalaemia
  • Hypoglycaemia
  • Hypothermia
  • Trauma
  • Tamponade
  • Tension pneumothorax
  • Thrombosis
  • Toxins
  • Alcohol
  • Epilepsy
  • Insulin and glycaemic changes
  • Overdose
  • Uraemia and metabolic causes
  • Trauma
  • Infection
  • Pressure – RICP
  • Psychiatric disorders
  • Stroke
  • Simple faint
  • Stokes-Adams
100

What category of drugs are Amphetamines? What are the effects of this category of drugs that explain Emma's clinical presentation?

Sympathomimetic toxidrome

  • Tachycardia, hypertension
  • Hyperthermia
  • Mydriasis
  • Hyperreflexia and increased muscle tone
100

What are some causes of hypernatremia?

High serum Na from deficit of water or from increased intake/retention of Na

Losing water (osmotic diuresis, vomiting, diarrhoea)

Diabetes insipidus (no ADH produced) = cannot reabsorb water

Reduced intake of water

100

Interpret these results:

Low pH

Low HCO3-

Normal CO2

Metabolic acidosis

200

Define 'coma' and compare it to 'brain death'?

Coma = unrousable unresponsiveness, but brainstem is preserved, reflexes preserved

Brain death = no brainstem reflexes (pupil light reflex, gag reflex etc.)

200

What is the MOA of Amphetamines e.g. MDMA?


Increased release and reduced reuptake of monoamine NT (Noradrenaline, Serotonin, Dopamine, Adrenaline)

200

Describe the normal regulation of high plasma osmolarity

Hypothalamic osmoreceptors detect

Increase ADH release to absorb water from urine into bloodstream

200

Interpret these results:

Low pH

Low HCO3-

Low CO2

Metabolic acidosis with respiratory compensation

300

What is her GCS score if:

She does not open her eyes

She does not vocalise

She grimaces to pain and slightly withdraws from pain

E1

V1

M4

Total GCS of 6

300

What is the MOA of Benzodiazepine?

It is also used to manage an overdose of which drugs?

GABA-A receptor agonist

Increase Cl- channel opening = influx = hyperpolarisation of neuron

Sedation, anticonvulsant, muscle relaxant

Manage Amphetamine overdose

300

Describe the normal regulation occurring in the body if there is high ECF volume.

Increased blood volume

Atrial distention = release of natriuretic peptides

Decreased aldosterone

300

Why did Emma present with both metabolic and respiratory acidosis?

Metabolic acidosis from stimulant drug = increased metabolic rate, increased CO2 production

Respiratory acidosis = cannot compensate due to aspiration pneumonia

400

Define consciousness?

What structures are involved in consciousness?

  • Access to memories
  • Self-awareness
  • Ability to manipulate abstract ideas
  • Focus attention

Diencephalon:

  • Thalamus, hypothalamus, epithalamus, ventral thalamus, 3rd ventricle

Reticular Activating System:

  • Located in the brainstem through the core of midbrain, pons, medulla
  • Midline Raphe with lateral and medial nuclei groups
  • Send continuous stream of impulses to the cortex to keep it alert and conscious and enhance excitability
  • Filters out repetitive/familiar/weak signals but unusual/significant/strong signals reach consciousness
400

Emma's urine was negative for opiates. What is the MOA of opiates? If she had overdosed on them, how would you manage her?

Binds to opioid receptors (mu, kappa, delta)

Induces euphoria, sedation, analgesia, respiratory depression

Management with supportive (ABC) and Naloxone opioid antagonist

400

What is hypovolaemic hypotonic hyponatremia?

What are some causes for it?

Volume depletion but losing more Na than water

Diuretics, polyuria, haemorrhage, excessive sweating

Volume depletion = ADH = reabsorb water into blood = higher blood volume relative to Na (exacerbates hyponatremia)

400

Immediate management involved intubation and ventilation using Rapid Sequence Induction. What does this mean?

Induces immediate unresponsiveness and muscular relaxation

Fastest and most effective means of controlling emergency airway

500

What neurotransmitter systems are associated with alertness and what are their respective nuclei?

Monoamine - serotonin (raphe), histamine (tuberomamillary), noradrenaline (locus coeruleus)

Cholinergic - brainstem (laterodorsal tegmental, pedunculopontine) to thalamus, and forebrain (basal nucleus of Meynert) to cortex

500

What is the drug we screen for in all potential OD patients? Explain its metabolism and how we would manage a patient with this OD.

Paracetamol

Phase 2 glucuronidation/sulphation, some converted by CYP2E1 to NABQI (toxic) but glutathione inactivates NABQI

In OD, phase 2 pathways saturated, more NABQI formed but insufficient glutathione to inactivate = hepatic necrosis, liver failure

Administer N-Acetyl-Cysteine within 10-12hrs of OD to restore glutathione levels and/or inactivate NABQI

500

Patients with SIADH often present with high urine osmolarity and low serum osmolarity. Explain why.

  • Increased ADH secretion = increased aquaporin channels in DCT
  • Increased reabsorption of water from urine into bloodstream
  • Less water in urine = higher urine osmolarity
  • Blood volume increases = serum osmolality decreases
  • Hypervolaemia also triggers the release of natriuretic peptides ANP, BNP
  • Decreased aldosterone release
  • Reduced absorption of Na (and water) = increased excretion of Na and water through the kidneys
500

Emma's base excess was decreased. What does this mean?

Lower than normal HCO3- in her blood

Due to primary metabolic acidosis or compensated respiratory alkalosis

500

Which recreational drug has severe cardiac complications including dysrhythmia and myocardial ischaemia? Explain why.

Cocaine

Inhibits re-uptake of dopamine, serotonin, noradrenaline from synapse

Noradrenaline acts on alpha 1 receptors (vascular smooth muscle) = vasoconstriction and hypertension

Acts on B1 (heart) = tachycardia

> myocardial infarction

Also inhibits Na+ channels = arrhythmias