Inhalational Poisoning

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Inhalational Poisoning

• Rama B. Rao, MD
• Bellevue Hospital Center/NYU Medical Center
• New York City Poison Control Center

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Classes

• Simple asphyxiants
• Pulmonary irritants

• Particulates
• Mitochondrial toxins

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Simple Asphyxiants

• Alveolar displacement O2
• Non-irritating
• No direct mitochondrial toxicity

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Simple Asphyxiants

• Methane
• Carbon dioxide (CO2)
• Helium
• Nitrogen
• Nitrous oxide

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Lake Nyos Carbon Dioxide
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Nitrogen
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Nitrous Oxide
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Simple Asphyxiants Symptoms

• Loss of consciousness
• Minimal warning
• Non-irritating
• Sustained exposure
• Hypoxia
• Cardiovascular collapse

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Simple Asphyxiants Treatment

• Safe rescue
• 100 oxygen
• Evaluation for other injuries
• Supportive care

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Pulmonary Irritants

• Can behave in part like simple asphyxiants
• Mucosal irritation
• Acid or base formation
• Some free radical formation

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Methyl Isocyanate
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Pulmonary Irritants Water Solubility

• Highly water soluble
• Ammonia
• Sulfur dioxide
• Hydrogen chloride
• Chloramine
• Rapid onset

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Pulmonary Irritants Intermediate Solubility

• Chlorine
• Exposure better tolerated initially
• Increased duration exposure
• Subsequent acid formation in upper and lower
  airways
• Delayed effects
• Acute lung injury

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Pulmonary Irritants Low Solubility

• Include
• Phosgene
• Nitrogen dioxide
• Prolonged exposure
• Delayed
• Pulmonary edema
• Acute lung injury

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Pulmonary Irritants Treatment

• Removal from exposure
• Oxygen
• Nebulized bronchodilators
• For acid forming agents
• Nebulized sodium bicarbonate
• 1 part NaHCO3 to 3 parts saline or water
• Primarily for symptomatic relief

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Pulmonary Irritants Treatment

• Supportive care
• Admission
• Severely symptomatic patients
• Low and intermediate solubility exposures
• Arrange follow-up

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Particulates and Aspirants

• Gas exchange impaired
• Supportive therapy
• Intubation
• ECMO
• Bronchoaveolar lavage
• Can be fatal in children

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Hydrocarbon Aspiration

• Surfactant disruption
• Higher severity
• Agents
• Low viscosity
• Surface tension
• High volatility
• gt30 mL exposures

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Hydrocarbon Aspiration Symptoms/Signs

• Cough
• Choking
• Dyspnea
• Rales
• Hypoxia
• May progress to ALI

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HC Aspiration Management

• Assess for evidence of aspiration
• Clinical
• Radiographic
• For asymptomatic patients without clinical
  evidence of aspiration
• Observe 6 hours
• Radiograph at 6 hours
• Admit if signs or symptoms aspiration

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Ware LB, N Engl J Med. 2000342(18)1334-49.
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MITOCHONDRIAL TOXINS
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Mitochondrial Toxins

• Carbon monoxide
• Cyanide
• Hydrogen sulfide

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Carbon Monoxide

• Incomplete combustion
• Fires
• Vehicular exhaust
• Methylene chloride
• Leading cause of poisoning deaths in the U.S

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Toxicity CO

• Displacement O2
• Alveoli
• Hemoglobin binding sites (OCC)
• Impaired O2
• Delivery
• Utilization

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CO Poisoning Acute Signs and Symptoms

• Headache
• Myalgias
• Dyspnea
• Nausea, Vomiting
• Loss of Consciousness
• Chest pain
• Hypotension

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CO Toxicity Delayed Events
Signs and Symptoms Signs and Symptoms
Dementia Amnesia Confabulation Memory impairment Ataxia Chorea Cortical blindness Incontinence Paralysis Hypokinesia Parkinsonism Tremor

• Delayed neurological/
• neuropsychiatric sequelae
• 2-40 days post-exposure
• Risks
• Age
• Loss of consciousness

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Physiology CO Binding

• Myocardium
• CV impairment ? Hypotension
• Hemoglobin
• Decreased OCC ? Functional Anemia
• Platelets and PMN
• Nitric oxide ? Hypotension
• Free radicals ? Lipid Peroxidation
• Mitochondria
• Cytochrome oxidase ? Lipid Peroxidation
• Impaired e transport ? Functional Hypoxia

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Carbon Monoxide Management

• 100 oxygen
• Reduce half-life CO-Hb 6hr to 90 minutes
• Assess for pregnancy
• Note that pulse oximetry is inadequate
• Oxygen saturation may appear artificially high
• Assess for end organ damage
• VS, ECG, symptomatology, neurological examination

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Carbon Monoxide Levels

• Venous sampling
• gt 10 abnormal
• Levels correlate poorly with severity of
  exposurre

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COHb levels () Symptoms Symptoms
1-2 Normal Normal
5-10 Smokers Smokers
10-20 Flu-like symptoms Flu-like symptoms
30-40 Fatigue Severe headache Fatigue Severe headache
40-50 Confusion loss of consciousness Confusion loss of consciousness
60-70 Coma Seizures CV collapse Death
gt70 Rapidly fatal Rapidly fatal
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Hyperbaric Oxygen

• Decrease COHb half life
• Displaces CO from tissues
• Improves oxygen carrying capacity
• Limits lipid peroxidation
• Improves dissolved oxygen

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Hyperbaric Oxygen

• Variable outcomes in literature 2?
• Definition of DNS
• Timing and duration of therapy
• Co-exposures
• Inability to define equivalent exposures
• Patient variability

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Hyperbaric Oxygen
Weaver LK, et al Hyperbaric oxygen for acute
carbon monoxide poisoning. N Engl J Med 2002
3471057-67
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Hyperbaric Oxygen Indications

• Neurological damage
• Cardiovascular events
• Loss of Consciousness
• Persistent symptoms
• COHb gt 25 ( some centers use gt40)
• COHb gt 15 in pregnant woman
• Ideally within 6 hours of exposure

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Cyanide

• Salts used in
• Electroplating
• Mining extraction
• Photography
• Jewelry
• Nitroprusside
• Amygdalins

Jim Jones, The Peoples Temple
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Cyanide

• Similar mechanism as CO
• Mitochondrial toxin
• Acute exposure
• Rapid onset
• Lactic acidosis
• Vomiting, seizures, coma

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Cyanide

• Salts
• Alkaline liquid
• Gas
• War
• Combustion

Zyklon B, WWII Auschwitz
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Cyanide Antidote Kit
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Cyanide Antidote Kit
Hemoglobin
Nitrites
Methemoglobin
Cyt a-a3 Mitochondria
Cyanide
Cyanomethemoglobin
Sodium Thiosulfate
Sodium Thiocyanate
Rhodanese
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Treatment Cyanide Antidote Kit

• Known or suspected cyanide poisoning
• Metabolic acidosis
• End organ damage

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Nitrites for CN
Caution
Caution if diagnosis is uncertain or if COHb is
also suspected. Can omit nitrites if uncertain
exposure.
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Hydroxocobalamin for CN
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Hydroxocobalamin Kit

• Sodium Thiosulfate 8 gm IV
• Hydroxocobalamin 4 gm IV
• Under investigation
• Anaphylactoid reaction
• May interfere with some lab assays

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Hydrogen Sulfide