Regarding the use of high-dose insulin euglycaemic therapy (HIET) for CCB toxicity, which ONE of the following statements is INCORRECT?
Answer: C: In severe CCB toxicity sudden cardiovascular collapse with cardiac arrest may occur in a patient who becomes shocked with bradycardia and hypotension. A shocked patient can soon be resistant to all treatments such as atropine, intravenous calcium, inotropes, vasopressors and cardiac pacing. Therefore early consideration for initiation of HIET is now being advocated for severe CCB toxicity. This is supported by more than 70 case reports of the use of this treatment.
HIET seems to help overcome the metabolic derangement, that is, the metabolic starvation state affecting the heart in severe CCB toxicity. Insulin enhances myocardial contractility, causing positive inotropy. However, insulin does not have any chronotropic activity and may cause vasodilation and therefore it may be best used with inotropes in severe toxicity.
HIET has been described as a safe treatment option with predictable and easily correctible adverse effects that may include hypoglycaemia, hypokalaemia, hypomagnesaemia and hypophosphataemia. The early detection of these potential adverse effects is important. Hypoglycaemia has been reported in only 16% of the published cases. As severe CCB toxicity may cause hyperglycaemia, in some patients hypoglycaemia may not occur despite high doses of insulin.
Reference:
Regarding intentional overdose with sulphonylurea drugs, which ONE of the following statements is TRUE?
Answer: C: In sulphonylurea toxicity the resultant hypoglycaemia typically occurs within 8 hours from the time of ingestion and it usually remains prolonged and severe. Hypoglycaemia is more severe in non-diabetics than in diabetics.
The specific antidote for hyperinsulinaemia induced by sulphonylurea is octreotide. Octreotide suppresses endogenous insulin release from pancreatic islet cells. Therefore early commencement of octreotide at the onset of hypoglycaemia is recommended in these patients. Octreotide can be commenced with an appropriate IV bolus dose followed by a continuous intravenous infusion for at least 24 hours. When a patient is on an octreotide infusion normoglycaemia can usually be maintained without the necessity to have a concurrent glucose infusion.
There is no indication to commence octreotide when there is no hypoglycaemia. Therefore, there is no place for prophylactic octreotide in these patients.
Intermittent boluses of high concentrated glucose (e.g. 50% glucose 50 mL) with a background 5–10% dextrose infusion to maintain euglycaemia is not the best way to manage hypoglycaemia in these patients. Intermittent glucose boluses stimulate endogenous insulin secretion and therefore potentially cause rebound hypoglycaemia.
References:
Regarding thyroxine overdose, which ONE of the following statements is TRUE?
Answer: C: The majority of patients remain asymptomatic following an acute overdose of thyroxine. Symptoms are not likely to occur following ingestion of <10 mg in adults and <5mg in children. The majority of patients experience mild to moderate symptoms after 2–7 days post-ingestion and therefore immediate cardiac monitoring or drug levels check in the first three days are not indicated. Clinically significant thyrotoxicosis is not reported in children after unintentional ingestion.
An elderly woman is brought in by ambulance with a history of intentional ingestion of a presumed large amount of eucalyptus oil within the last 30 minutes. She is fully conscious and has normal vital signs.
Which ONE of the following treatments is LEAST likely to be required for this patient in the ED?
Answer: A: Eucalyptus oil is a type of commonly available essential oil and is a hydrocarbon. Both ingested and inhaled hydrocarbons can cause CNS depression, coma and seizure in large overdoses. The onset of these symptoms usually occurs within 1–2 hours. Aspiration of hydrocarbons may produce a chemical pneumonitis characterized by initial coughing and subsequent tachypnoea, hypoxia, wheeze and pulmonary oedema. The initial symptoms of this may appear 4–6 hours later and gradually get worse.
Consequently gastrointestinal decontamination is contraindicated and activated charcoal does not bind hydrocarbons. For chemical pneumonitis oxygen, bronchodilators, non-invasive ventilation (NIV) or intubation may be required. Seizure control should be achieved with intravenous benzodiazepines.
Eucalyptus or other essential oil of 10 mL or more in an adult and 5 mL or more in a child may cause severe CNS toxicity leading to rapid coma and seizures.
Regarding carbon monoxide poisoning, which ONE of the following statements is TRUE?
Answer: B: In most acute carbon monoxide (CO) poisonings (e.g. deliberate inhalation of car exhaust fumes) reaching hospital, although the concentration of CO is high, the duration of exposure is usually limited. Consequently, the risk of development of long-term neuropsychological sequelae is low. The opposite is true for low-concentration long-duration accidental exposures in occupational or domestic situations. In moderate to severe toxicity the patient presents more with generalized neurological features than focal features. These may include initial transient loss of consciousness, headache, nausea, visual disturbances, ataxia, confusion, seizures and coma. Ischaemic cardiac injury may occur but is uncommon.
The required duration of normobaric oxygen treatment is not well established for symptomatic patients. It is recommended that symptomatic patients receive 100% oxygen until all symptoms have resolved. The use of hyperbaric oxygen is controversial except in some high-risk patients such as pregnant women.
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