calcium becomes bioavailable, which is unlikely in the setting of hemodynamic instability or poor liver function during cardiac arrest. Calcium chloride is preferably given intravenously via a central or a large peripheral line to avoid any potentially harmful effects should extravasation occur.
Hyperkalaemia raises the resting membrane potential, causing a narrowing between resting membrane potential and threshold potential for action potential generation. Calcium restores this initial narrowing back towards 15 mV by raising the threshold potential to being ‘less negative’. Calcium results in improvement in ECG changes within minutes of administration.
Calcium is essential for normal muscle and nerve activity. It transiently increases peripheral resistance, myocardial excitability and contractility. Randomized control trials and observational studies have demonstrated no survival benefits when calcium was given in‐hospital or out‐of‐hospital cardiac arrest patients. In VF, calcium did not restore spontaneous circulation.
Ahee P. The management of hyperkalaemia in the emergency department. Emergency Medicine Journal. 2000;17(3):188–191.https://emj.bmj.com/content/17/3/188
34. Answer: J
This patient’s cardiac monitor demonstrates torsade de pointes. It is the result of QTc prolongation which can either be congenital or acquired. Acquired QTc prolongation is most often drug‐related. There are many medications that can predispose a person to torsades such as antiarrhythmics, antipsychotics, antiemetics, antifungals, and antimicrobials. Prolonged QTc and Torsades are also associated with hypokalaemia, hypocalcaemia, hypomagnesemia, bradycardia, and heart failure.
Magnesium is an electrolyte essential for membrane stability. Hypomagnesaemia causes myocardial hyperexcitability particularly in the presence of hypokalaemia and digoxin. Electrical cardioversion should be performed for patients with hypotension or in cardiac arrest from torsades de pointes. Intravenous magnesium is the first‐line pharmacologic therapy of torsades de pointes. The recommended initial dose of magnesium is a slow 2 g IV push. An infusion of 1g to 4 g/hr should be started to keep the magnesium levels >2 mmol/L. Once the magnesium level is >3 mmol/L, the infusion can be stopped. Severe magnesium toxicity is seen with levels >3.5 mmol/L which can cause confusion, respiratory depression, and cardiac arrest. It is important to remember to correct any hypokalaemia as well. There is insufficient data to recommend for or against its routine use in cardiac arrest.
There are many causes of hypomagnesaemia. Heavy binge alcohol intake can lead to a loss of magnesium from tissues and increased urinary loss. Chronic alcohol abuse has been reported to deplete the total body supply of magnesium. This is the most likely cause in this case.
Schwartz PJ. Predicting the Unpredictable Drug‐Induced QT Prolongation and Torsades de Pointes. J Am Coll Cardiol 2016; 67:1639–50.
https://www.sciencedirect.com/science/article/pii/S0735109716003387
35. Answer: K
This case is a very typical occurrence in hospital. The patient is in pain after the fracture and is waiting for surgery. He receives opioid analgesia regularly. Opiate toxicity should be suspected when the clinical triad of depressed level of consciousness (reduced GCS), respiratory depression, and pupillary miosis are present. It is important to remember opioid exposure/toxicity does not always result in miosis and that respiratory depression is the most specific sign. Respiratory failure and respiratory acidosis is due to hypoventilation.
Airway control and adequate oxygenation is the primary supportive treatment. Intravenous naloxone should be given in patient with reduced level of consciousness and/or respiratory depression. The usual dose is between 0.4 and 2 mg. The onset of effect following intravenous naloxone is 1–2 min; maximal effect is observed within 5–10 min. A repeat dose is indicated for partial response and can be repeated as often as needed. To avoid precipitous withdrawal (nausea, vomiting, agitation) and consequent aspiration, naloxone may be started with low doses such as 0.1 mg and titrated up gradually until reversal of respiratory depression is achieved.
Boyer E. Management of Opioid Analgesic Overdose. New England Journal of Medicine. 2012;367(2):146–155.
https://pubmed.ncbi.nlm.nih.gov/22784117/
3 Dermatology
Questions
Answers can be found in the Dermatology Answers section at the end of this chapter.
1 1. A 65‐year‐old man with a history of type 2 diabetes presents with blistering skin lesions affecting the trunk and upper and lower extremities. Histopathology of a punch biopsy and an excision biopsy of the affected skin and blister confirms a diagnosis of bullous pemphigoid.Which one of the following medications may have contributed to the development of bullous pemphigoid?Gliclazide.Insulin.Linagliptin.Metformin.
2 2. A 27‐year‐old woman with an 18‐year history of type 1 diabetes and a 5‐year history of hypothyroidism now presents with fatigue, bloating, abdominal pain, diarrhoea, and a 4 kg weight loss over the past 6 months. On examination, she has symmetric papulovesicles over the external surface of the extremities and on the trunk.What other classic characteristic of her skin lesion would you expect to find?Absence of any pain.Firm nodules on the scalp.Intense pruritus.Target lesions on the palms.
3 3. A 34‐year‐old woman has developed several tender red swellings on her shins and right ankle (picture shown below) over the past 3 weeks. She has been feeling generally unwell and has a low‐grade fever. She has not had a recent sore throat, cough, or sputum. Over the past 12 months she has had recurrent aphthous ulcers in her mouth but no genital ulceration. She has also experienced intermittent abdominal pain, diarrhoea, and lost 7 kg of body weight. She is a current heavy smoker and drinks alcohol only occasionally. On examination, she is afebrile, there are no aphthous ulcers, active arthritis, lymphadenopathy, or organomegaly. The initial investigation results and CXR are displayed below.TestsResultsNormal valuesSodium136 mmol/L135–145Potassium3.5 mmol/L3.5–5.2Urea5.9 mmol/L2.7–8.0Creatinine96 μmol/L60–100Calcium2.01 mmol/L2.10–2.60Albumin28 g/L38–48Bilirubin16 mmol/L2–24ALP63 U/L30–110GGT46 U/L0–60ALT52 U/L0–55AST45 U/L0–45Hb92 g/L135–175WBC16.5 x 109/L4.0–11.0Platelet259 x 109/L150–450MCV72 fL80–98ESR82 mm/h<20What is your most likely diagnosis?Crohn’s disease.Glandular fever.Lymphoma.Sarcoidosis.
4 4. An 18‐year‐old man presents to the emergency department with central colicky abdominal pain and arthralgia. He has become unwell with coryzal symptoms since yesterday. He reports smoky coloured urine and reduced oral intake due to sore throat. He does not have a significant past medical history and no history of intravenous drug use. On examination, a palpable rash is present on both legs (see below). He is hypertensive. Which of the following statement regarding this condition is correct?80% of patients will have a negative FOBT.90% of patients will have high level of serum IgA.90% of patients will have thrombocytopenia.90% of patients will have a positive ANCA and MPO.
5 5.
