Hydrocarbons and Inhaled Toxins

Question 1

List the 4 types of toxic exposures to hydrocarbons

Answer 1

1. Accidental ingestions (generally children younger then 5)
2. Intentional inhalational abuse
3. Accidental inhalation or dermal exposure – often occupational
4. Massive oral ingestion in a suicide attempt

Question 2

List the hydrocarbons most sought by abusers for eurphoria and disinhibition (also confusion and obtundation)?

Answer 2

1. Toluene
2. benzene
3. gasoline
4. butane
5. chlorinated hydrocarbons

Question 3

How do hydrocarbons target the CNS/CV in toxicity

Answer 3

CNS: Work like general anesthetics
GABA activation

CV: sensitizes myocardium
Na channel/K channel blockers (prolong QRS and QT

Question 4

What physical characteristics increase toxicity

Answer 4

1, volatile

2. low viscosity
3. low surface tension

Question 5

How do hydrocarbons cause lung injury

Answer 5

1. asphyxiant (displaces O2)
2. inhibit surfactant production
3. direct damage to alveoli
4. Irritant: bronchospasm and inflammation

Question 6

List 5 neurologic consequences of chronic use of inhaled hydrocarbons.

Answer 6

• Peripheral neuropathy
• Cerebellar degeneration
• Neuropsychiatric disorders
• Chronic encephalopathy
• White matter dementia

Question 7

What is paitner’s syndrome?

Answer 7

• Mostly from chronic toluene exposure
  
  • Ataxia, spacticity, dysarthria, dementia
  • Consistent with leukoencephalopathy

Question 8

List 3 subacute complications of HC aspiration / ingestion:

Answer 8

1. Pneumonia
2. PTx
3. Pneumatocele

Question 9

List 4 reasons why patients with HC toxicity can be cyanotic:

Answer 9

1. asphyxiant
2. VQ mismatch
3. methemoglobinemia
4. Hypoventilation from ALOC

Question 10

What hydrocarbons need intestinal decontamination

Answer 10

CHAMP
C: camphor (seizures and status)
H: Halogenated hydrocarbons (dysrhthmias and hepatotoxicity)
A: aromatic hydrocarbons: bone marrow supression and cancer
M: metal containing HC eg arsenic, mercury, lead
P: pesticide containing HC: cholinergic crisis , sz, resp depression)

Question 11

How are inhaled toxins classified

Answer 11

simple asphyxiant: inert gas that displaces O2
pulmonary irritant: produce acid/base or oxygen radical
chemical asphyxiant: eg CO a gas that has higher affinity for Hb than O2

Question 12

What adjunct therapy may provide symptomatic relief after exposure to chlorine or hydrogen chloride gas?

Answer 12

Nebulized 2% sodium bicarb

May have delayed S up to 24 hrs

Question 13

List 3 ways that CO results in toxicity:

Answer 13

• Interacts with deoxyhemoglobin to form carboxyhemoglobin (COHb) (cannot carry oxygen)
• Shift to the left (interfering with ability to release oxygen)
• Interferes with cellular respiration by binding to mitochondrial cytochrome oxidase (increased binding during hypotension and hypoxia)

Question 14

What abnormalities on imaging can be seen with CO toxicity?

Answer 14

CT head: Bilateral hypodensities in globus pallidus and internal capsule, seen after the acute exposure (below)

Question 15

List risk factors that predict poor outcome after CO poisoning?

Answer 15

• Extremes of age
• Pregnancy (poor fetal outcome)
  Pre-existing coronary artery / respiratory disease

Question 16

What is the half life of CO

Answer 16

Room air: 5 hrs
100% FiO2: 90 min
HBO 30 min

Question 17

What are the indications for HBO2

Answer 17

GT 25% adult or 15% pregnant/peds

LOC, coma, sz, confusion, cardiac ischemia, GT 24hrs of exposure, fetal distress

Question 18

Where do CN, H2S and CO bind?

Answer 18

Fe3+ containing cytochrome a3 in the electron transport chain. Intereferes with aerobic metabolism leading to lactate generation

Question 19

What are lab findings suggestive of CN toxicity

Answer 19

lactate GT 7

decreased arterial-venous O2 difference

Question 20

What is the dose of hydroxycobalamin

Answer 20

5g IV over 15 min will turn skin, mm and urine red

Question 21

List 4 knockdown toxins

Answer 21

HCN
H2S
volatile nerve agents
CO