100 ECG’s
Electrolyte Disorders: (4 questions)

Questions

• 1
  A 60 year old gentleman with a long standing history of chronic kidney disease due to diabetes attends the emergency department. He is on the right mixture of medications, including lisinopril, insulin and atorvastatin. He says he has recently felt very drowsy and weak. The ECG is shown. What is the best initial course of action ?
  
  Difficulty: Easy     Topic: Electrolyte Disorders
  a

  Nebulised Salbutamol

  b

  IV calcium gluconate

  c

  IV salbutamol

  d

  IV insulin and dextrose

  e

  IV bicarbonate
  Explanation: The ECG shows tall tented T waves and a broad QRS. These changes are typical for hyperkalaemia, likely a consequence of an acute on chronic decompensation of his chronic kidney disease which is iatrogenically exacerbated (ACE inhibitors increase potassium). The best initial treatment is cardioprotection with 10ml of 10% calcium gluconate.
• 2
  A 57 year old gentleman with end-stage renal failure is admitted to the emergency department with drowsiness and confusion. On examination, he has a dialysis fistula in his left arm, a rapid respiratory rate, and decreased deep tendon reflexes. You perform an ECG (shown) followed by an arterial blood gas. What is the most likely acid-base status in this patient ?
  
  Difficulty: Medium     Topic: Electrolyte Disorders
  a

  Metabolic Acidosis

  b

  Metabolic Alkalosis

  c

  Normal

  d

  Respiratory Acidosis

  e

  Respiratory Alkalosis
  Explanation: The ECG shows tall tented T waves a broad QRS with absent P-wavesa and a grossly prolonged QT-interval. These changes are typical for hyperkalaemia plus hypocalcaemia, likely a consequence of his end-stage renal failure. Symptoms of hyperkalaemia are non-specific but include drowsiness and confusion. Signs include depressed tendon reflexes. In these patients, a blood gas is important as it immediately gives you a potassium level. What you also see on the blood gas is a "Metabolic Acidosis" picture due to the transcellular shift of extracellular potassium for intracellular hydrogen leading to a metabolic acidaemia.
• 3
  A 52 year old man with longstanding heart failure develops severe viral gastroenteritis and vomiting. He has vomited up to ten times a day and has become very drowsy. His wife accompanies him but doesn’t remember his complete past medical or drug histories, although she does recall him being on a “water tablet”. An ECG is performed (shown). What is the most likely diagnosis?
  
  Difficulty: Medium     Topic: Electrolyte Disorders
  a

  Hypercalcaemia

  b

  Hypocalcaemia

  c

  Hyperkalaemia

  d

  Hypokalaemia

  e

  Hypomagnesemia
  Explanation: The ECG shows T-wave flattening/inversion, P-R prolongation, and large U-waves, classical for hypokalaemia. Vomiting leads to metabolic alkalosis which leads to a transcellular shift of extracellular potassium for intracellular hydrogen, decreasing the circulating potassium. In addition, it is likely that Furosemide is the watertablet used for his heart failure which contributes to hypokalaemia. The best course of action is potassium replacement.
• 4
  You are called to a cardiac arrest situation during one of your night shifts. You arrive and resuscitation is ongoing. You are handed an ECG (shown) and asked to identify any reversible causes which can be addressed in this patient. Which of the following is a reversible cardiac arrest cause in this patient ?
  
  Difficulty: Medium     Topic: Electrolyte Disorders
  a

  Hypothermia

  b

  Hyperkalaemia

  c

  Hypokalaemia

  d

  Cardiac tamponade

  e

  Pulmonary embolus (right heart strain)
  Explanation: This ECG shows tall-tented T-waves and broad QRS complexes. This is consistent with a diagnosis of Hyperkalaemia which is a reversible cause of cardiac arrest. Addressing this condition with medical management or ITU management may assist in the resuscitation effort in bringing about a return of spontaneous circulation (ROSC).