Medical Management Guidelines for Hydrogen Cyanide
(HCN)
CAS# 74-90-8, 143-33-9, 151-50-8, 592-01-8, 544-92-3,
506-61-6, 460-19-5, 506-77-4
UN# 1051
PDF Versionpdf icon[659 KB]
Synonyms include formonitrile. Aqueous
solutions are referred to as hydrocyanic acid and prussic
acid.
- Persons whose clothing or skin is contaminated with cyanide-containing
solutions can secondarily contaminate response personnel
by direct contact or through off-gassing vapor.
- Hydrogen cyanide is a colorless or pale-blue liquid at
room temperature. It is very volatile, readily producing
flammable and toxic concentrations at room temperature.
Hydrogen cyanide gas mixes well with air, and explosive
mixtures are easily formed.
- Hydrogen cyanide has a distinctive bitter almond odor,
but some individuals cannot detect it and consequently,
it may not provide adequate warning of hazardous concentrations.
- Hydrogen cyanide is absorbed well by inhalation and can
produce death within minutes. Substantial absorption can
occur through intact skin if vapor concentration is high
or with direct contact with solutions, especially at high
ambient temperatures and relative humidity. Exposure by
any route may cause systemic effects.
General Information
Description
At temperatures below 78ºF, hydrogen
cyanide is a colorless or pale-blue liquid (hydrocyanic acid);
at higher temperatures, it is a colorless gas. Hydrogen cyanide
is very volatile, producing potentially lethal concentrations
at room temperature. The vapor is flammable and potentially
explosive. Hydrogen cyanide has a faint, bitter almond odor
and a bitter, burning taste. It is soluble in water and is
often used as a 96% aqueous solution.
Routes of Exposure
Inhalation
Hydrogen cyanide is readily absorbed
from the lungs; symptoms of poisoning begin within seconds
to minutes. The odor of hydrogen cyanide is detectable at
2-10 ppm (OSHA PEL = 10 ppm), but does not provide adequate
warning of hazardous concentrations. Perception of the
odor is a genetic trait (20% to 40% of the general population
cannot detect hydrogen cyanide); also, rapid olfactory fatigue
can occur. Hydrogen cyanide is lighter than air.
Children exposed to the same levels of
hydrogen cyanide as adults may receive larger doses because
they have greater lung surface area:body weight ratios and
increased minute volumes:weight ratios.
Skin/Eye Contact
Exposure to hydrogen cyanide can cause
skin and eye irritation. More importantly, skin or eye absorption
is rapid and contributes to systemic poisoning. After skin
exposure, onset of symptoms may be immediate or delayed for
30 to 60 minutes. Most cases of toxicity from dermal exposure
have been from industrial accidents involving partial immersion
in liquid cyanide or cyanide solutions or from contact with
molten cyanide salts, resulting in large surface-area burns.
Children are more vulnerable to toxicants
absorbed through the skin because of their relatively larger
surface area:body weight ratio.
Ingestion
Ingestion of hydrogen cyanide solutions
or cyanide salts can be rapidly fatal.
Sources/Uses
Hydrogen cyanide is manufactured by oxidation
of ammonia- methane mixtures under controlled conditions and
by the catalytic decomposition of formamide. It may be generated
by treating cyanide salts with acid, and it is a combustion
by-product of nitrogen-containing materials such as wool,
silk, and plastics. It is also produced by enzymatic hydrolysis
of nitriles and related chemicals. Hydrogen cyanide gas is
a by-product of coke-oven and blast-furnace operations.
Hydrogen cyanide is used in fumigating;
electroplating; mining; and in producing synthetic fibers,
plastics, dyes, and pesticides. It also is used as an intermediate
in chemical syntheses.
Standards and Guidelines
OSHA PEL (permissible exposure limit)
(ceiling) = 10 ppm (skin) (averaged over 15 minutes)
NIOSH IDLH (immediately dangerous to
life or health) = 50 ppm
AIHA ERPG-2 (emergency response planning
guideline) (maximum airborne concentration below which it
is believed that nearly all individuals could be exposed for
up to 1 hour without experiencing or developing irreversible
or other serious health effects or symptoms which could impair
an individual's ability to take protective action) = 10 ppm
Physical Properties
Description: Colorless gas or
colorless or pale-blue liquid
Warning properties: Almond odor
at >l ppm; inadequate warning for acute or chronic exposure
Molecular weight: 27.03 daltons
Boiling point (760 mm Hg): 78ºF
(25.6ºC)
Freezing point: 8ºF (-13.4ºC)
Specific gravity (liquid): 0.69
(water = 1)
Vapor pressure: 630 mm Hg at 68ºF
(20ºC)
Gas density: 0.94 (air = 1)
Water solubility: Flammable at
temperatures >0ºF (-18ºC)
Flammability: flammable limits
3.9% to 21.8% at room temperature
Flammable range: 5.6% to 40% (concentration
in air)
Incompatibilities
Hydrogen cyanide reacts with amines,
oxidizers, acids, sodium hydroxide, calcium hydroxide, sodium
carbonate, caustic substances, and ammonia. Hydrogen cyanide
may polymerize at 122ºF to 140ºF.
Health Effects
- Hydrogen cyanide is highly toxic by all routes of exposure
and may cause abrupt onset of profound CNS, cardiovascular,
and respiratory effects, leading to death within minutes.
- Exposure to lower concentrations of hydrogen cyanide may
produce eye irritation, headache, confusion, nausea, and
vomiting followed in some cases by coma and death.
- Hydrogen cyanide acts as a cellular asphyxiant. By binding
to mitochondrial cytochrome oxidase, it prevents the utilization
of oxygen in cellular metabolism. The CNS and myocardium
are particularly sensitive to the toxic effects of cyanide.
Acute Exposure
In humans, cyanide combines with the
ferric ion in mitochondrial cytochrome oxidase, preventing
electron transport in the cytochrome system and bringing oxidative
phosphorylation and ATP production to a halt. The inhibition
of oxidative metabolism puts increased demands on anaerobic
glycolysis, which results in lactic acid production and may
produce severe acid-base imbalance. The CNS is particularly
sensitive to the toxic effects of cyanide, and exposure to
hydrogen cyanide generally produces symptoms within a short
period of time.
Children do not always respond to chemicals
in the same way that adults do. Different protocols for managing
their care may be needed.
CNS
CNS signs and symptoms usually develop
rapidly. Initial symptoms are nonspecific and include excitement,
dizziness, nausea, vomiting, headache, and weakness. As poisoning
progresses, drowsiness, tetanic spasm, lockjaw, convulsions,
hallucinations, loss of consciousness, and coma may occur.
Cardiovascular
Abnormal heartbeat can occur in cases
of severe poisoning. Slow heartbeat, intractable low blood
pressure, and death may result. High blood pressure and a
rapid heartbeat may be early, transient findings.
Respiratory
After systemic poisoning begins, victims
may complain of shortness of breath and chest tightness. Pulmonary
findings may include rapid breathing and increased depth of
respirations. As poisoning progresses, respirations become
slow and gasping; a bluish skin color may or may not be present.
Accumulation of fluid in the lungs may develop. Children may
be more vulnerable to gas exposure because of relatively increased
minute ventilation per kg and failure to evacuate an area
promptly when exposed.
Metabolic
An anion-gap, metabolic acidosis occurs
in severe poisoning from increased blood levels of lactic
acid.
Because of their higher metabolic rates,
children may be more vulnerable to toxicants interfering with
basic metabolism.
Dermal
Dermal contact with hydrogen cyanide can cause skin irritation.
Dermal absorption can occur, leading to systemic toxicity. Absorption occurs more readily at high ambient temperature and relative humidity.
Because of their relatively larger surface area:body weight ratio, children are more vulnerable to toxicants absorbed through the skin.
Ocular/Ophthalmic
When splashed in the eye, hydrogen cyanide can cause eye irritation and swelling. Eye contact with cyanide salts has produced systemic symptoms in experimental animals. Dilated pupils are common in severe poisoning. Transient blindness can occur, although it rarely does.
Potential Sequelae
Survivors of severe exposure may suffer
brain damage due to a direct action on neurons, or to lack
of oxygen, or possibly due to insufficient blood circulation.
Cases of neurologic sequelae such as personality changes,
memory deficits, disturbances in voluntary muscle movements,
and the appearance of involuntary movements (i.e., extrapyramidal
syndromes) have been reported.
Chronic Exposure
Chronically exposed workers may complain
of headache, eye irritation, easy fatigue, chest discomfort,
palpitations, loss of appetite, and nosebleeds.
Chronic exposure may be more serious
for children because of their potential longer life span.
Carcinogenicity
Hydrogen cyanide has not been classified
for carcinogenic effects, and no carcinogenic effects have
been reported for hydrogen cyanide.
Reproductive and Developmental Effects
No reproductive or developmental effects
of hydrogen cyanide have been reported in experimental animals
or humans. Hydrogen cyanide is not included in Reproductive
and Developmental Toxicants, a 1991 report published by
the U.S. General Accounting Office (GAO) that lists 30 chemicals
of concern because of widely acknowledged reproductive and
developmental consequences. Increased levels of thiocyanate
in the umbilical cords of fetuses whose mothers smoked compared
to those whose mothers were non-smokers suggests that thiocyanate,
and possibly also cyanide, can cross the placenta. No data
were located pertaining to hydrogen cyanide in breast milk.
Prehospital Management
- Victims exposed only to hydrogen cyanide gas do not pose
secondary contamination risks to rescuers, but do not attempt
resuscitation without a barrier. Victims whose clothing
or skin is contaminated with hydrogen cyanide liquid or
solution can secondarily contaminate response personnel
by direct contact or through off-gassing vapor. Avoid dermal
contact with cyanide-contaminated victims or with gastric
contents of victims who may have ingested cyanide-containing
materials.
- Hydrogen cyanide poisoning is marked by abrupt onset of
profound toxic effects that may include syncope, seizures,
coma, gasping respirations, and cardiovascular collapse,
causing death within minutes. These effects can occur from
all routes of exposure.
- Victims exposed to hydrogen cyanide require supportive
care and rapid administration of specific antidotes.
Hot Zone
Rescuers should be trained and appropriately
attired before entering the Hot Zone. If the proper equipment
is not available, or if rescuers have not been trained in
its use, assistance should be obtained from a local or regional
HAZMAT team or other properly equipped response organization.
Rescuer Protection
Hydrogen cyanide is a highly toxic systemic
poison that is absorbed well by inhalation and through the
skin.
Respiratory Protection: Positive-pressure,
self-contained breathing apparatus (SCBA) is recommended in
response situations that involve exposure to potentially unsafe
levels of hydrogen cyanide.
Skin Protection: Chemical-protective
clothing is recommended because both hydrogen cyanide vapor
and liquid can be absorbed through the skin to produce systemic
toxicity.
ABC Reminders
Quickly access for a patent airway, ensure
adequate respiration and pulse. If trauma is suspected, maintain
cervical immobilization manually and apply a cervical collar
and a backboard when feasible.
Victim Removal
If victims can walk, lead them out of
the Hot Zone to the Decontamination Zone. Victims who are
unable to walk may be removed on backboards or gurneys; if
these are not available, carefully carry or drag victims to
safety.
Consider appropriate management of chemically
contaminated children, such as measures to reduce separation
anxiety if a child is separated from a parent or other adult.
Decontamination Zone
Patients exposed only to hydrogen cyanide
gas who have no eye irritation do not need decontamination.
They may be transferred immediately to the Support Zone. Other
patients will require decontamination as described below.
Rescuer Protection
If exposure levels are determined to
be safe, decontamination may be conducted by personnel wearing
a lower level of protection than that worn in the Hot Zone
(described above). However, do not attempt resuscitation
without a barrier.
ABC Reminders
Quickly access for a patent airway, ensure
adequate respiration and pulse. Stabilize the cervical spine
with a collar and a backboard if trauma is suspected. Administer
supplemental oxygen as required. Assist ventilation with a
bag-valve-mask device if necessary.
Basic Decontamination
Speed is critical. For symptomatic
victims, provide treatment with 100% oxygen and specific antidotes
as needed. Treatment should be given simultaneously with decontamination
procedures. (For treatment, see ABC Reminders, Advanced
Treatment, and Antidotes below).
Victims who are able may assist with
their own decontamination. Rapidly remove contaminated clothing
while flushing exposed skin and hair with plain water for
2 to 3 minutes, then wash twice with mild soap. Rinse thoroughly
with water. Double-bag contaminated clothing and personal
belongings. Use caution to avoid hypothermia when decontaminating
children or the elderly. Use blankets or warmers when appropriate.
Irrigate exposed or irritated eyes with
plain water or saline for 5 minutes. Continue eye irrigation
during other basic care or transport. Remove contact lenses
if easily removable without additional trauma to the eye.
In cases of ingestion, do not induce
emesis. If the victim is alert, asymptomatic, and has
a gag reflex, administer a slurry of activated charcoal (administer
at 1 gm/kg, usual adult dose 60-90 g, child dose 25-50 g).
A soda can and a straw may be of assistance when offering
charcoal to a child. If the victim is symptomatic, immediately
institute emergency life support measures including the use
of the cyanide antidote kit (see Antidotes below).
Consider appropriate management of chemically
contaminated children, such as measures to reduce separation
anxiety if a child is separated from a parent or other adult.
If possible, seek assistance from a child separation expert.
Transfer to Support Zone
As soon as basic decontamination is complete,
move the victim to the Support Zone.
Support Zone
Be certain that victims have been decontaminated
properly (see Decontamination Zone above). Victims
who have been decontaminated or who have been exposed only
to vapor generally pose no serious risks of secondary contamination
to rescuers. In such cases, Support Zone personnel require
no specialized protective gear.
ABC Reminders
Quickly access for a patent airway. If
trauma is suspected, maintain cervical immobilization manually
and apply a cervical collar and a backboard when feasible.
Ensure adequate respiration and pulse. Administer supplemental
oxygen as required and establish intravenous access if necessary.
Place on a cardiac monitor.
Patients who rapidly regain consciousness
and who have no other signs or symptoms may not require antidotal
treatment. Those who remain comatose or develop shock should
be treated promptly with the antidotes in the cyanide antidote
kit (see Antidotes below).
Additional Decontamination
Continue irrigating exposed skin and
eyes, as appropriate.
In cases of ingestion, do not induce
emesis. If activated charcoal has not been administered
previously, and the victim is alert, asymptomatic, and has
a gag reflex, administer a slurry of activated charcoal (administer
at 1 gm/kg, usual adult dose 60-90 g, child dose 25-50 g).
A soda can and a straw may be of assistance when offering
charcoal to a child. If the patient is symptomatic, immediately
institute emergency life support measures, including the use
of a cyanide antidote kit (see Antidotes below).
Advanced Treatment
In cases of respiratory compromise secure
airway and respiration via endotracheal intubation. If not
possible, perform cricothyroidotomy if equipped and trained
to do so.
Patients who are in shock or have seizures
should be treated according to advanced life support (ALS)
protocols. These patients or those who have arrhythmias may
be seriously acidotic; consider giving, under medical supervision,
each patient 1 mEq/kg intravenous sodium bicarbonate.
Antidotes
When possible, treatment with cyanide
antidotes should be given under medical supervision to unconscious
victims who have known or strongly suspected cyanide poisoning.
Cyanide antidotes-amyl nitrite perles and intravenous infusions
of sodium nitrite and sodium thiosulfate-are packaged in the
cyanide antidote kit.
Amyl nitrite perles should be broken
onto a gauze pad and held under the nose, over the Ambu-valve
intake, or placed under the lip of the face mask. Inhale for
30 seconds every minute and use a new perle every 3 minutes
if sodium nitrite infusions will be delayed.
If the patient has not responded to oxygen
and amyl nitrite treatment, infuse sodium nitrite intravenously
as soon as possible. The usual adult dose is 10 mL of a 3%
solution (300 mg) infused over absolutely no less than
5 minutes; the average pediatric dose is 0.12 to 0.33
mL/kg body weight up to 10 mL infused as above. Monitor blood
pressure during sodium nitrite administration, and slow the
rate of infusion if hypotension develops.
Next, infuse sodium thiosulfate intravenously.
The usual adult dose is 50 mL of a 25% solution (12.5 g) infused
over 10 to 20 minutes; the average pediatric dose is 1.65
mL/kg of a 25% solution. Repeat one-half of the initial dose
30 minutes later if there is an inadequate clinical response.
Transport to Medical Facility
Only decontaminated patients or patients
not requiring decontamination should be transported to a medical
facility. "Body bags" are not recommended.
Report to the base station and the receiving
medical facility the condition of the patient, treatment given,
and estimated time of arrival at the medical facility.
If a cyanide-containing solution has
been ingested, prepare the ambulance in case the victim vomits
toxic material. Have ready several towels and open plastic
bags to quickly clean up and isolate vomitus.
Multi-Casualty Triage
Consult with the base station physician
or the regional poison control center for advice regarding
triage of multiple victims.
Patients with evidence of significant
hydrogen cyanide exposure, and all patients who have hydrogen
cyanide ingestion should be transported to a medical facility
for evaluation.
Patients who have only brief inhalation
exposure and mild or transient symptoms may be discharged
from the scene after their names, addresses, and telephone
numbers are recorded. They should be advised to seek medical
care promptly if symptoms develop or recur (see Patient
Information Sheet below).
Emergency Department Management
- Hospital personnel in an enclosed area can be secondarily
contaminated by vapor off-gassing from heavily soaked clothing
or skin, or from toxic vomitus. Avoid dermal contact with
cyanide-contaminated patients or with gastric contents of
patients who may have ingested cyanide-containing materials,
Patients do not pose secondary contamination risks after
contaminated clothing is removed and the skin is washed.
- Hydrogen cyanide poisoning is marked by abrupt onset of
profound toxic effects that may include syncope, seizures,
coma, gasping respirations, and cardiovascular collapse,
causing death within minutes.
- Patients exposed to hydrogen cyanide can survive with
supportive care and rapid administration of specific antidotes.
Decontamination Area
Previously decontaminated patients and
patients exposed only to hydrogen cyanide gas who have no
skin or eye irritation may be transferred immediately to the
Critical Care Area. Other patients require decontamination
as described below.
ED personnel should don butyl rubber
gloves and aprons before treating patients who have been exposed
to hydrogen cyanide liquid or solutions. (Hydrogen cyanide
readily penetrates most rubbers and barrier fabrics or creams,
but butyl rubber provides good skin protection for a short
period of time.)
Be aware that use of protective equipment
by the provider may cause fear in children, resulting in decreased
compliance with further management efforts.
Because of their relatively larger surface
area:body weight ratio, children are more vulnerable to toxicants
absorbed through the skin. Also, emergency room personnel
should examine children's mouths because of the frequency
of hand-to-mouth activity among children.
ABC Reminders
Evaluate and support airway, breathing,
and circulation. In cases of respiratory compromise secure
airway and respiration via endotracheal intubation. If not
possible, surgically create an airway.
Patients who are comatose, hypotensive,
or have seizures or cardiac dysrhythmias should be treated
in the conventional manner. If not previously administered,
give sodium bicarbonate intravenously to these patients. Further
bicarbonate therapy should be guided by ABG measurements.
Basic Decontamination
Patients who are able may assist with
their own decontamination.
Speed is critical. If the patient
is symptomatic, immediately institute emergency life support
measures, including the use of the cyanide antidote kit (see
Antidotes and Other Treatments below).
If the patient's clothing is wet with
hydrogen cyanide solution, quickly remove contaminated clothing
while flushing exposed skin and hair with plain water for
2 to 3 minutes (preferably under a shower), then wash twice
with mild soap. Use caution to avoid hypothermia when decontaminating
children or the elderly. Use blankets or warmers when appropriate.
Rinse thoroughly with water. Double-bag
contaminated clothing and personal belongings.
Irrigate exposed eyes for at least 5
minutes. Remove contact lenses if easily removable without
additional trauma to the eye. Continue irrigation while transporting
the patient to the Critical Care Area.
In cases of ingestion, do not induce
emesis. If activated charcoal has not been administered
previously, and the victim is alert, asymptomatic, and has
a gag reflex, administer a slurry of activated charcoal (administer
at 1 gm/kg, usual adult dose 60-90 g, child dose 25-50 g).
A soda can and a straw may be of assistance when offering
charcoal to a child. Consider gastric lavage if the patient
is conscious and it can be performed shortly after ingestion.
Because cyanide absorption from the gut is rapid, the effectiveness
of activated charcoal will depend on how quickly after ingestion
it can be administered. Isolate gastric washings and vomitus;
they may off-gas hydrogen cyanide.
Critical Care Area
Be certain that appropriate decontamination
has been carried out (see Decontamination Area above).
ABC Reminders
Evaluate and support airway, breathing,
and circulation as in ABC Reminders above. Establish
intravenous access in seriously ill patients if this has not
been done previously. Continuously monitor cardiac rhythm.
Patients who are in shock or have seizures
should be treated according to ALS protocols. These patients
or those who have dysrhythmias may be seriously acidotic;
consider giving 1 mEq/kg intravenous sodium bicarbonate.
Inhalation Exposure
Inhalation is the primary route of exposure
to hydrogen cyanide. Refer to Antidotes and Other Treatments
below for appropriate clinical treatment of systemic effects.
Skin Exposure
If the skin contacted hydrogen cyanide
liquid or cyanide solutions, chemical burns may occur; treat
as thermal burns. Watch for signs or symptoms of systemic
toxicity, which may be delayed in onset for up to 1 hour.
Eye Exposure
Continue irrigation for at least 15 minutes.
Test visual acuity. Examine the eyes for corneal damage and
treat appropriately. Immediately consult an ophthamologist
for patients who have corneal injuries.
Ingestion Exposure
Do not induce emesis. If the victim is symptomatic, immediately
institute emergency life support measures including the use
of a cyanide antidote kit (see Antidotes and Other
Treatments below). If the victim is alert, asymptomatic,
has a gag reflex, and it has not been done previously, perform
gastric lavage and give activated charcoal as soon as possible.
Because cyanide absorption from the gut is rapid, the usefulness
of activated charcoal will depend on how quickly after ingestion
it can be administered.
Administer a slurry of activated charcoal
at 1 gm/kg (usual adult dose 60-90 g, child dose 25-50 g).
A soda can and a straw may be of assistance when offering
charcoal to a child.
Toxic vomitus or gastric washings should
be isolated (e.g., by attaching the lavage tube to isolated
wall suction or another closed container).
Antidotes and Other Treatments
Patients who have signs or symptoms of
significant systemic toxicity should be evaluated for antidotal
treatment. In the United States, antidotes for cyanide include
amyl nitrite perles and intravenous infusions of sodium nitrite
and sodium thiosulfate, which are packaged in the cyanide
antidote kit.
If one dose of the antidotes from the
kit has been administered previously by prehospital personnel
and inadequate clinical response has occurred, a second dose
of one-half the initial amounts may be given 30 minutes after
the initial dose. Further doses should be guided by the patient's
clinical condition and not by the percentage of methemoglobin
induced. The usual methods of monitoring methemoglobin levels
are unreliable in cases of cyanide poisoning and may seriously
underestimate the levels of inactive hemoglobin.
Amyl nitrite perles should be broken
onto a gauze pad and held under the nose, over the Ambu-valve
intake, or placed under the lip of the face mask. Inhale for
30 seconds every minute and use a new perle every 3 minutes
if sodium nitrite infusions will be delayed.
If the patient has not responded to oxygen
and amyl nitrite treatment, infuse sodium nitrite intravenously
as soon as possible. The usual adult dose is 10 mL of a 3%
solution (300 mg) infused over absolutely no less than 5 minutes;
the average pediatric dose is 0.12 to 0.33 mL/kg body weight
up to 10 mL infused as above. Monitor blood pressure during
sodium nitrite administration, and slow the rate of infusion
if hypotension develops.
Next, infuse sodium thiosulfate intravenously.
The usual adult dose is 50 mL of a 25% solution (12.5 g) infused
over 10 to 20 minutes; the average pediatric dose is 1.65
mL/kg of a 25% solution. Repeat one-half of the initial dose
30 minutes later if there is an inadequate clinical response.
Amyl nitrite and sodium nitrite oxidize
the ferrous iron of hemoglobin to methemoglobin. Methemoglobin
levels should not exceed 20%. Repeat treatment with nitrite
and thiosulfate as required.
The efficacy of hyperbaric oxygen in
cyanide poisoning is unproven. It has been reported to be
useful in severe cases of smoke inhalation combined with exposure
to hydrogen cyanide and carbon monoxide.
Laboratory Tests
The diagnosis of acute cyanide toxicity
is primarily a clinical one (based on rapid onset of CNS toxicity
and cardiorespiratory collapse). Laboratory testing is useful
for monitoring the patient and evaluating complications. Routine
laboratory studies for all exposed patients include CBC, blood
glucose, and electrolyte determinations. Additional studies
for patients exposed to hydrogen cyanide include ECG monitoring,
determinations of serum lactate, chest radiography, and pulse
oximetry (or ABG measurements).
In severe poisonings, venous blood is
oxygenated and has a bright red color. Elevated venous PO2
and venous percent O2 saturation occurs, narrowing
the gap between arterial and central venous PO2
or percent O2 saturation.
After treatment with nitrites, serum
methemoglobin levels may be monitored. However, the usual
methods of monitoring methemoglobin levels are unreliable
in cases of cyanide poisoning and may seriously underestimate
the levels of inactive hemoglobin. Alternative methods exist,
but may not be available. Whole blood cyanide tests generally
require several hours and cannot be used to guide emergency
treatment. However, blood cyanide levels may be useful in
documenting exposure.
Disposition and Follow-up
Consider hospitalizing patients who have
histories of significant exposure and are symptomatic. Whenever
infusions from the cyanide antidote kit are used, the patient
should be admitted to the intensive care unit
Delayed Effects
Patients who have ingested hydrogen cyanide
solutions or patients who have direct skin or eye contact
should be observed in the Emergency Department for at least
4 to 6 hours.
Patient Release
Patients who remain asymptomatic 4 to
6 hours after exposure may be discharged with instructions
to seek medical care promptly if symptoms develop (see the
Hydrogen Cyanide- Patient Information Sheet below).
Follow-up
Obtain the name of the patient's primary
care physician so that the hospital can send a copy of the
ED visit to the patient's doctor.
Survivors of a serious exposure should
be evaluated for ischemic damage to the brain and heart. Patients
who have serious systemic cyanide poisoning may be at risk
for CNS sequelae including Parkinsonian-like syndromes; they
should be monitored for several weeks to months.
Patients who have corneal injuries should
be reexamined within 24 hours.
Reporting
If a work-related incident has occurred,
you may be legally required to file a report; contact your
state or local health department.
Other persons may still be at risk in
the setting where this incident occurred. If the incident
occurred in the workplace, discussing it with company personnel
may prevent future incidents. If a public health risk exists,
notify your state or local health department or other public
agency. When appropriate, inform patients that they may request
an evaluation of their workplace from OSHA or NIOSH. See Appendices
III and IV for a list of agencies that may be of assistance.
Patient Information Sheet
This handout provides information and
follow-up instructions for persons who have been exposed to
hydrogen cyanide.
Print instructions only.pdf icon[PDF - 45.7 KB]
What is hydrogen cyanide?
At room temperature, hydrogen cyanide
is a volatile, colorless-to-blue liquid (also called hydrocyanic
acid). It rapidly becomes a gas that can produce death in
minutes if breathed. Hydrogen cyanide is used in making fibers,
plastics, dyes, pesticides, and other chemicals, and as a
fumigant to kill rats. It is also used in electroplating metals
and in developing photographic film.
What immediate health effects can be caused by exposure to hydrogen cyanide?
Breathing small amounts of hydrogen cyanide
may cause headache, dizziness, weakness, nausea, and vomiting.
Larger amounts may cause gasping, irregular heartbeats, seizures,
fainting, and even rapid death. Generally, the more serious
the exposure, the more severe the symptoms. Similar symptoms
may be produced when solutions of hydrogen cyanide are ingested
or come in contact with the skin.
Can hydrogen cyanide poisoning be treated?
The treatment for cyanide poisoning includes
breathing pure oxygen, and in the case of serious symptoms,
treatment with specific cyanide antidotes. Persons with serious
symptoms will need to be hospitalized.
Are any future health effects likely to occur?
A single small exposure from which a
person recovers quickly is not likely to cause delayed or
long-term effects. After a serious exposure, a patient may
have brain or heart damage.
What tests can be done if a person has been exposed to hydrogen cyanide?
Specific tests for the presence of cyanide
in blood and urine generally are not useful to the doctor.
If a severe exposure has occurred, blood and urine analyses
and other tests may show whether the brain or heart has been
injured. Testing is not needed in every case.
Where can more information about hydrogen cyanide be found?
More information about hydrogen cyanide
can be obtained from your regional poison control center;
your state, county, or local health department; the Agency
for Toxic Substances and Disease Registry (ATSDR); your doctor;
or a clinic in your area that specializes in occupational
and environmental health. If the exposure happened at work,
you may wish to discuss it with your employer, the Occupational
Safety and Health Administration (OSHA), or the National Institute
for Occupational Safety and Health (NIOSH). Ask the person
who gave you this form for help in locating these telephone
numbers.
Follow-up Instructions
Keep this page and take it with you to
your next appointment. Follow only the instructions
checked below.
Print instructions only.pdf icon[PDF - 45.7 KB]
[ ] Call your doctor or the Emergency
Department if you develop any unusual signs or symptoms within
the next 24 hours, especially:
- difficulty breathing, shortness of breath, or chest pain
- confusion or fainting
- increased pain or a discharge from your eyes
- increased redness, pain, or a pus-like discharge in the
area of a skin burn
[ ] No follow-up appointment is necessary
unless you develop any of the symptoms listed above.
[ ] Call for an appointment with Dr.____
in the practice of ________.
When you call for your appointment, please
say that you were treated in the Emergency Department at _________
Hospital by________and were advised to be seen again in ____days.
[ ] Return to the Emergency Department/Clinic
on ____ (date) at _____ AM/PM for a follow-up examination.
[ ] Do not perform vigorous physical
activities for 1 to 2 days.
[ ] You may resume everyday activities
including driving and operating machinery.
[ ] Do not return to work for _____days.
[ ] You may return to work on a limited
basis. See instructions below.
[ ] Avoid exposure to cigarette smoke
for 72 hours; smoke may worsen the condition of your lungs.
[ ] Avoid drinking alcoholic beverages
for at least 24 hours; alcohol may worsen injury to your stomach
or have other effects.
[ ] Avoid taking the following medications:
________________
[ ] You may continue taking the following
medication(s) that your doctor(s) prescribed for you: _______________________________
[ ] Other instructions:
____________________________________
_____________________________________________________
- Provide the Emergency Department with the name and the
number of your primary care physician so that the ED can
send him or her a record of your emergency department visit.
- You or your physician can get more information on the
chemical by contacting: ____________ or _____________, or by
checking out the following Internet Web sites:
___________;__________.
Signature of patient _______________ Date ____________
Signature of physician _____________ Date ____________
Where can I get more information?
If you have questions or concerns, please contact your community or state health or environmental quality department or:
For more information, contact:
Agency for Toxic Substances and Disease Registry
Division of Toxicology and Human Health Sciences
4770 Buford Highway
Chamblee, GA 30341-3717
Phone: 1-800-CDC-INFO 888-232-6348 (TTY)
Email: Contact CDC-INFO
ATSDR can also tell you the location of occupational and environmental health clinics. These clinics specialize in recognizing, evaluating, and treating illnesses resulting from exposure to hazardous substances.