Sun28November0628PM 12

Four politicians are rushed into the Emergency department. They were set upon by an individual as they left a meeting. The individual had two aerosol cans which he sprayed in front of their faces.

On presentation, all of the men had profuse lacrimation, chemosis, pain around the eyes and injected cornea. Slit-lamp examination revealed severe corneal injuries. There was no demonstrable neurological deficit in any of the patients, but all four men complained of shortness of breath, cough and wheeze. All the men were pyrexic, nauseated, and all developed diarrhoea within two hours of admission.

Initially, blood gases were normal, but after two hours, arterial blood gases in the most severely affected man showed:

On FiO2 35% -

pO2 8.0 kPa (11.3-12.6)

pCO2 6.5 kPa (4.7-6.0)

HCO3 30 mmol/L -

Base Excess -2 mmol/L (+/- 2)

Within 18 hours, the two men who had received the greatest exposure to the spray had developed haemoptysis and progressive dyspnoea. Chest x ray at this time showed bilateral pleural effusions, with widespread alveolar shadowing. The severely affected patients were intubated and ventilated but, with maximal supportive care, they died; one 36 hours later, the other at 40 hours.

The two surviving patients received full supportive care, but also required intubation and ventilation. Both men required treatment for pulmonary oedema, and severe dehydration secondary to profuse, blood stained diarrhoea. One of the men had an OGD after an episode of melaena which showed widespread, severe, inflammatory gastritis. Both men eventually recovered after a prolonged hospital stay.

What was the substance present in the aerosol that is most likely to have caused the described syndrome in these patients?

(Please select 1 option)

Ricin Correct

Anthrax

Sarin

Pepper spray

Paraquat

Explanation

Given the circumstances, the current political climate, and the rising risk of bioterrorism, vigilance is required in the emergency department.

The arterial blood gases show acute respiratory failure. In this case, the rapid time course to severe symptoms and death would be unusual for infectious agents. Anthrax is therefore unlikely.

Pepper spray gives symptoms which last for approximately 40 minutes and is not associated with death, unless it leads to exacerbation of asthma/chronic obstructive pulmonary disease.

Paraquat usually requires ingestion to be fatal, but it can be absorbed through mucous membranes. Usually, inhalation of spray is unlikely to cause systemic toxicity because of its low vapour pressure and the large droplets that are formed.

Sarin has muscarinic and nicotinic effects.

Muscarinic effects:

Paralysis

Fasciculations

Hyperglycaemia, and

Ketosis.

Nicotinic effects:

Hypotension

Meiosis

Dyspnoea, and

GI disturbance.

There is not a great deal of evidence of how ricin poisoning inhalation may present, but animal studies and anecdotal reports of deaths caused by ricin poisoning give us a good idea.

The above clinical situation accurately describes the symptoms of ricin poisoning. Laboratory findings in ricin inhalation are non-specific but similar to other pulmonary irritants which cause pulmonary oedema. When inhaled as a small particle aerosol, this toxin may produce pathologic changes within eight hours and severe respiratory symptoms followed by acute hypoxic respiratory failure in 36-72 hours. An affected patient may have massive bleeding from the stomach and intestines. The patient is most likely to die from multiple organ failure.

Ricin's toxicity lies in its ability to inhibit protein synthesis, via the endonuclease activity of its A-chain.

Answer Statistics

1

26%

2

17%

3

29%

4

2%

5

29%

Times answered: 317