Hydrocarbons and Inhaled Toxins Flashcards
List the 4 types of toxic exposures to hydrocarbons
- Accidental ingestions (generally children younger then 5)
- Intentional inhalational abuse
- Accidental inhalation or dermal exposure – often occupational
- Massive oral ingestion in a suicide attempt
List the hydrocarbons most sought by abusers for eurphoria and disinhibition (also confusion and obtundation)?
- Toluene
- benzene
- gasoline
- butane
- chlorinated hydrocarbons
How do hydrocarbons target the CNS/CV in toxicity
CNS: Work like general anesthetics
GABA activation
CV: sensitizes myocardium
Na channel/K channel blockers (prolong QRS and QT
What physical characteristics increase toxicity
1, volatile
- low viscosity
- low surface tension
How do hydrocarbons cause lung injury
- asphyxiant (displaces O2)
- inhibit surfactant production
- direct damage to alveoli
- Irritant: bronchospasm and inflammation
List 5 neurologic consequences of chronic use of inhaled hydrocarbons.
- Peripheral neuropathy
- Cerebellar degeneration
- Neuropsychiatric disorders
- Chronic encephalopathy
- White matter dementia
What is paitner’s syndrome?
- Mostly from chronic toluene exposure
- Ataxia, spacticity, dysarthria, dementia
- Consistent with leukoencephalopathy
List 3 subacute complications of HC aspiration / ingestion:
- Pneumonia
- PTx
- Pneumatocele
List 4 reasons why patients with HC toxicity can be cyanotic:
- asphyxiant
- VQ mismatch
- methemoglobinemia
- Hypoventilation from ALOC
What hydrocarbons need intestinal decontamination
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)
How are inhaled toxins classified
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
What adjunct therapy may provide symptomatic relief after exposure to chlorine or hydrogen chloride gas?
Nebulized 2% sodium bicarb
May have delayed S up to 24 hrs
List 3 ways that CO results in toxicity:
- 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)
What abnormalities on imaging can be seen with CO toxicity?
CT head: Bilateral hypodensities in globus pallidus and internal capsule, seen after the acute exposure (below)
List risk factors that predict poor outcome after CO poisoning?
- Extremes of age
- Pregnancy (poor fetal outcome)
Pre-existing coronary artery / respiratory disease
What is the half life of CO
Room air: 5 hrs
100% FiO2: 90 min
HBO 30 min
What are the indications for HBO2
GT 25% adult or 15% pregnant/peds
LOC, coma, sz, confusion, cardiac ischemia, GT 24hrs of exposure, fetal distress
Where do CN, H2S and CO bind?
Fe3+ containing cytochrome a3 in the electron transport chain. Intereferes with aerobic metabolism leading to lactate generation
What are lab findings suggestive of CN toxicity
lactate GT 7
decreased arterial-venous O2 difference
What is the dose of hydroxycobalamin
5g IV over 15 min will turn skin, mm and urine red
List 4 knockdown toxins
HCN
H2S
volatile nerve agents
CO
