Environmental and exposures

Question 1

How does CO toxicity present?

Answer 1

Sources- vehicle exhaust, indoor fires, old machinery, faulty heating devices, smoking (10-15%), Hookah use (up to 30%) and exposure to methylene chloride

CO causes immediate hypoxia by binding to Hb at 210x the affinity of 02

Also causes endothelial oxidative injury and activates inflammatory cascade (likely the cause of delayed neurological sequelae)

Acute exposures produce life threatening effects, but chronic exposures carry high risk of neurological sequelae (dementia, psychosis, neuropathy, ataxia etc)

Question 2

What are the symptoms/signs of acute CO toxicity?

Answer 2

Poor correlation with measured levels in those with chronic exposure

<10% COHb = nil
10-30 = vague symptoms or nil
30-50 = GI upset, headache, collapse, confusion, weakness, lactate HAGMA
50-60 = Arrhytmias, coma, seizures, APO, DIC, Rhabdo
70-80 = multiorgan failure, death

CO at high doses causes direct CNS necrosis

Question 3

How does Hydroflouric acid toxicity change with type of exposure?

Answer 3

Dermal
- Extreme pain, variable levels of local tissue damage, the higher the concentration the fast ther onset
- Low conc may take >24hrs for symptoms to manifest

Inhalation
- Cough, wheeze, SOB
- ARDS, haemorrhagic pneumonitis

Question 4

What is the elimination rates of CO with varying 02 administration techniques?

Answer 4

RA = 4-5hrs
100% 02 = 40-80mins
3ATM = 23mins

Question 5

What are the effects of Arsenic poisoning?

Answer 5

Hypersalivation and garlic odour are the hallmarks

Encephalopathy, seizures, CVS collapse
Bone marrow suppression at 24-72hrs

Antidotes are Succimer and Dimercaprol

Question 6

How is Hydroflouric acid toxicity risk stratified?

Answer 6

• ECG’s
• VBG/Electrolytes

Question 7

What are the pros/cons of the different regional techniques for calcium administration with hydroflouric acid burns?

Answer 7

Question 8

What are the features of ingestion of caustic substances?

Answer 8

Risk
- pH <2 or >12
- Solids worse than liquids
- Absence of upper airway burns doesn’t preclude GI injury

Treatment
- Early intubation if airway burns
- Endoscopy at 6-24hr mark (lower risk of perforation) if no evidence of perforation
- Supportive care, NBM
- Consider steroids to reduce stricture formation in select cases

Who to discuss with surgery?
- Strong acids or alkali
- Markedly symptomatic
- Unable to tolerate oral intake at the 4-hr mark

Question 9

What are the features of Organophosphate toxicity?

Answer 9

• Delayed neurotoxicity’
• Chronic organophosphate induced neuropsychiatric disorder

Question 10

What are the main essential oils and there syndromes from exposure?

Answer 10

Eucalyptus Oil
- Most common
- 5mls can be toxic in children
- CNS depression, seizures, bronchospams, aspiration pneumonitis, GI upset, CVS collapse, HAGMA and multiorgan failure

Clove/Pennyroyal Oil
- Marked hepatotoxicity

Oil of Wintergreen
- Salicylate highly concentrated

Question 11

What is the classic presentation of Botulism?

Answer 11

Classic
- Bilateral cranial nerve neuropathies with progressive descending paralysis
- No fever, altered sensation or altered mental status

Infant
- Starts with constipation/poor feeding
- Descending paralysis
- Often have autonomic effects and anticholinergic like syndrome
- Pupillary paralysis and ptosis
- Treated with BabyBIG

Don’t give aminoglycosides as can worsen the NMJ blockade

Question 12

How does radiation exposure present? what is the treatment?

Answer 12

Basics
- Acute illness usually requires 1Gy (100Rads) to manifest
- >10Gy is universally fatal
- Alpha particles can be ingested or adherent to clothes/skin, requiring decontamination
- Healthcare workers rarely affected by secondary exposure, use droplet/contact precautions +/- lead for protection
- Death can occur days to months later
- Absolute lymphocyte count is the best prognosticator at 48hrs, <1.5 is abnormal and suggests large exposure

Risk Assessment
- Distance from source
- Time exposed
- Amount of radiation exposed to, measured in mSv/sec

Symptoms
- GI upset is the 1st to occur
- Malaise, fever, conjunctivitis
- Bone marrow suppression at doses >1-2Gy, often the cause of death
- doses >10Gy can cause CVS and neuro symptoms, with coma and cardiovascular collapse

Management
- Decontaminate including shower, warm soapy water including hair, get rid of clothes in safe manner
- Isolation room
- Supportive care for affected body systemts
- Potassium iodide 130mg QID for thyroid protection