• 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. 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).
• Hydrogen cyanide is highly toxic by all routes of exposure. The amount of cyanide, the duration of exposure, the route of exposure all influence the time of onset and the severity of illness.
• The time of onset of symptoms typically is seconds following inhalation of gaseous hydrogen cyanide and may cause abrupt onset of profound CNS, cardiovascular, and respiratory effects, leading to death within minutes.
• Liquid agent, which is readily absorbed through skin (especially in young children and pregnant women) can produce symptoms immediately or be delayed up to an hour.
• Responders should obtain assistance in identifying the chemical(s) from container shapes, placards, labels, shipping papers, and analytical tests. General information on these identification technicques is located in Emergency Response Guidebook.
• Identification Tools - CHEMM-IST, WISER, Cyanide Chemical Properties
• Devices - M256A1 chemical agent detector kit (liquid and vapor), Chemical Agent Detector C2 Kit (liquid and vapor), M18A3, M90 chemical agent detectors (vapor), Draeger CDS Kit (vapor and aerosol), M272 chemical water testing, Hazmat Smart Strips (qualitative)
• A comprehensive source for the selection of chemical identification equipment is the Guide for the Selection of Chemical Detection Equipment for Emergency First Responders, Guide 100-06, January 2007, 3rd Edition published by the Department of Homeland Security to assist with this process.

Hydrogen cyanide is a highly toxic systemic poison that is absorbed well by inhalation and through the skin. 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.

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.

PPE required; Level B-C is generally adequate depending on the ambient temperature and distance the hospital is from hot/warm zones (bring in HAZMAT if Level As are needed).

• Level A - protective clothing is the highest level of protection. Level A includes a Self Contained Breathing Apparatus (SCBA) with a fully encapsulating vapor tight suit with gloves and booties attached to the suit (tanks last from 1/2 hour to 1 hour).
• Level B - requires the use of SCBA but has lesser skin protection. Level Bs are chemical resistant suits that are designed for splashes of liquids but not for gas or vapor hazards. A young soldier can last about 2 hours on a hot day with a external air hose.
• Level C is similar to B with the exception of the type of respiratory protection. The SCBA is replaced with an Air Purifying Respirator.
• Level D protective clothing is utilized when there are no respiratory hazard and no major skin hazard considerations. Level D for hospital personnel includes scrubs, safety glasses, shoe covers, and possibly a face shield

Link to reference section for acute event PPE related safety information

Chemical casualty triage is based on walking feasibility, respiratory status, age, and additional conventional injuries. The triage officer must know the natural course of a given injury, the medical resources immediately available, the current and likely casualty flow, and the medical evacuation capabilities. General principles of triage for chemical exposures (cyanide specific triage foci) are presented in the management section.

• SALT Mass Casualty Triage - United States Government Recommendation
• START Adult Triage Algorithm
• JumpSTART Pediatric Triage Algorithm

• Check triage tag/card for any previous treatment or triage.
• Survey for evidence of associated traumatic/blast injuries.
• Observe for sweating, labored breathing, coughing/vomiting, secretions.
• Severe casualty triaged as immediate if assisted breathing is required.
• For blast injuries or other trauma, where there is question whether there is chemical exposure, victims must be tagged as immediate in most cases. Blast victim's evidence delayed effects such as ARDS, etc.
• Mild/moderate casualty: self/buddy aid, triaged as delayed or minimal and release is based on strict follow-up and instructions.
• If there are chemical exposure situations which may cause delayed but serious signs and symptoms, then over-triage is considered appropriate to the proper facilities that can observe and manage any delayed onset symptoms.
• Expectant categories in multi-casualty events are those victims who have experienced a cardiac arrest, respiratory arrest, or continued seizures immediately. Resources should not be expended on these casualties if there are large numbers of casualties requiring care and transport with minimal or scant resources available.
• In a given category prioritize a child, pregnant woman over a non-pregnant adult.

High concentrations of cyanide gas can cause death in minutes; however, low concentrations may produce symptoms gradually, causing challenges for the triage officer. Generally a person exposed to a lethal amount of cyanide will die within 5 to 10 minutes of exposure.

Immediate - Unconscious/seizures, apnea, severe airway, GI or skeletal muscle involvement.

If circulation is still intact, antidotes will restore the patient to a reasonably functional status in a short period of time.

Delayed - Significant but not life threatening respiratory involvement/systemic effects i.e. lethergy and mental status changes.

Minimal - Walking and talking patients.

Casualties exposed to cyanide vapor who have survived for 15 minutes can be categorized as minimal or delayed.

Contamination of conventional injuries with cyanide can result in respiratory depression and reduction of the oxygen carrying capacity of the blood. Urgent use of cyanide poisoning antidote is required. Oxygen therapy combined with positive pressure resuscitation may be required sooner in the presence of marked hemorrhage from the conventional injury. Opiates and other drugs that reduce respiratory drive must be used with extreme caution.

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.

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. Consider IO (utilizing drill) placement for rapid antidote administration.

• Link to Basic and Advanced Life Support
• Link to Pediatric Basic and Acute Life Support
• Link to Key Acute Care Adult Medications section
• Link to Key Acute Care Pediatric Medications section
• Link to Primary and Secondary Survey

Cyanide agent's means of inducing toxicity is through inhalation and skin/eye contact.

• The clinical signs of poisoning following significant vapor inhalation begin in seconds to minutes after exposure.
• Liquid agent, which is readily absorbed through skin (especially in young children and pregnant women) can produce symptoms immediately or be delayed up to an hour.
• Ingestion can occur via terrorist induced contamination of water/food supply or toddler hand to mouth behavior.
• Link - hospital management - treatment of cyanide ingestion

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.

Children exposed to the same level of cyanide agents as adults will usually receive higher doses because they have greater lung surface area: body weight ratios and increased minute volume: weight ratios.

• CNS - Initial signs and symptoms especially with lower dose exposures are nonspecific and include excitement, dizziness, nausea and vomiting, headache and weakness. Progression of symptoms (pending exposure levels) can include increased lethargy, tetany, convulsions, and loss of consciousness. Young children, especially under the age of four, are more prone to develop seizure disorders secondary to hypoxia or other CNS insult.
• Cardiovascular - Cardiovascular effects - Initially bradycardia and hypertension may occur followed by hypotension and tachycardia. The terminal event is consistently bradycardia and hypotension.
• Respiratory - Initial patient findings may include increased respiratory rate, shortness of breath and chest tightness. With progression of poisoning, respirations become slow and gasping. Central cyanosis may or may not occur. Pulmonary edema may occur.
• Metabolic - Acidosis occurs secondary to increased anerobic respiration.
• Dermal - Systemic absorption can occur. High ambient temperate, relative humidity results in increased absorption. A cherry red skin color may be present as the result of increased venous hemoglobin oxygen saturation. Cyanide does not directly cause cyanosis. If present, it is secondary to shock. Children are more vulnerable to these toxicants being absorbed through the skin because their skin is thinner, contains more moisture, and they have a larger surface area to weight ratio than adults. Pregnant women also will have increased absorption through the skin because of the increased vascularity and vasodilatation associated with pregnancy.
• Ocular - Direct contact to liquid cyanide can result in eye irritation and swelling.
• GI toxicity following ingestion of cyanide may occur. This may include abdominal pain, nausea and vomiting.
• Link to Toxic Syndromes
• Link to Primary and Secondary Survey

• In mass casualty events cyanide or nerve agents can both present with sudden loss of consciousness followed by convulsions and apnea. Nerve agents typically have miosis, copious oral and nasal secretions, and muscle fasiciculations. Cyanide has normal or dilated pupils, few secretions and muscular twitching.
• Cherry red skin color is suggestive of cyanide toxicity
• One would have to have a high index of suspicion to focus on cyanide as the etiology of an individual presenting with loss of consciousness followed by convulsions and apnea as this chain of events is common as the result of multiple etiologies. However in a mass casualty event there are only three agents that can be dispensed by aerosol or gas that can cause a group of people to simultaneously fall, lose consiousness and seize; nerve agents, cyanide, and possibly hydrogen sulfide.
• Link to Chemcial Hazards Emergency Medical Management Intelligent Syndrome Tool (CHEMM-IST)

• Children exposed to the same level of cyanide agents as adults will usually receive higher doses because they have greater lung surface area: body weight ratios and increased minute volume: weight ratios.
• Young children, especially under the age of four, are more prone to develop seizure disorders secondary to hypoxia or other CNS insult.
• Children are more vulnerable to these toxicants being absorbed through the skin because their skin is thinner, contains more moisture, and they have a larger surface area to weight ratio than adults.
• In animal studies, it has been documented that sodium thiosulfate does not cross the placenta when utilized to treat cyanide toxicity but by treating the mother the cyanide levels in the fetus were lowered.
• Link to Primary and Secondary Survey

Victims exposed to hydrogen cyanide require supportive care (including administration of 100 % oxygen) and rapid administration of specific antidotes. Cyanide agent specific antidotes and supportive treatment may have to be initiated prior to decontamination.

Antidote Dosing and Sequencing:

When possible, treatment with cyanide antidotes should be given under medical supervision to unconscious victims who have known or strongly suspected cyanide poisoning. Amyl nitrite can be given quickly without IV or IO access. AMYL and SODIUM NITRITE have the potential to put the fetus of a pregnant woman at serious risk. In addition, there is increased vulnerability of infants and young children, those with active respiratory disease or diminished pulmonary reserve as well as those who have cardiovascular disease, particularly the elderly or frail, to increased methemoglobin levels (especially if combined with carbon monoxide exposure). If you are treating a patient that is not oxygenating well (such as a fire victim) consider starting treatment with hydroxocobalamin or sodium thiosulfate.

Therefore, initial treatment with hydroxocobalamin is recommended vs. amyl and sodium nitrite in pregnant women, infants, young children (especially with co morbidities such as smoke inhalation). An IO needle can be placed in the hot/warm zones while wearing level A PPEs to facilitate treatment.

• Cyanide antidotes - amyl nitrite‡* perles and intravenous infusions of sodium nitrite†§ and sodium thiosulfate†* - are packaged in the cyanide antidote kit.
  • Amyl nitrite perle should be broken onto a gauze pad and heal under the nose, placed under the lip of a facemask, or over the Ambu-valve intake. The patient should inhale for 30 seconds of each minute and a new perle should be utilized every three minutes if sodium nitrite infusions will be delayed. CAUTION AMYL NITRITE MAY CAUSE SIGNIFICANT HYPOTENSION AND IF TAKEN WITH DRUGS LIKE VIAGRA, CIALIS, OR LEVITRA (OTHER NITRITE-CONTAINING DRUGS), THIS EFFECT IS MAGNIFIED, POTENTIALLY CAUSING FAINTING AND EVEN DEATH.
  • As soon as IV access has been achieved in a symptomatic patient DC the perles and initiate IV sodium nitrite (ASAP).
    • The usual adult dose is 10 ml of a 3 % solution (300 mg).
    • The pediatric dose is 0.12 to 0.33 ml/kg.
    • It should be infused over no less than 5 minutes (monitor BP frequently).
    • If hypotension develops slow rate down consider giving crystalloids and vasopressors.
    • In patients who initially improve with nitrite therapy, but then exhibit signs or symptoms of hypoxia/cyanosis, a diagnosis of methemoglobinemia should be considered in the differential diagnosis along with continued cyanide toxicity. See methylene blue treatment.
  • Follow-up immediately with IV sodium thiosulfate (12.5 grams infused over 10 - 20 minutes).
    • The adult dose is 50 ml of a 25 % solutio.
    • The pediatric dose is 1.65 mL/kg of a 25 % solution.
    • Repeat one-half of the initial dose in 30 minutes if there is an inadequate clinical response or at 2 hours for prophylaxis.
• Hydroxocobalamin
  • A dose of 70 mg/kg (not to exceed 5 grams initially) administered over 15 minutes is recommended. This dose can be given IV push in situations of cyanide induced cardiac arrest. (Adult† Pediatric‡ Pregnancy§)
  • Depending upon the severity of the poisoning and the clinical response, a second dose of 70 mg/kg (not to exceed 5 g) may be administered by intravenous infusion for a total dose of 10 g. The rate of infusion for the second dose may range from 15 minutes (for patients in extremis) to two hours, as clinically indicated
  • Many patients with cyanide poisoning will be hypotensive; however, elevations in blood pressure have also been observed in known or suspected cyanide poisoning victims. Elevations in blood pressure (≥180 mmHg systolic or ≥110 mmHg diastolic) were observed in approximately 18% of healthy subjects (not exposed to cyanide) receiving hydroxocobalamin 5 g and 28% of subjects receiving 10 g. Increases in blood pressure were noted shortly after the infusions were started; the maximal increase in blood pressure was observed toward the end of the infusion. These elevations were generally transient and returned to baseline levels within 4 hours of dosing.
  • While a safe drug, animal and anecdotal human studies have demonstrated limited or no additional therapeutic benefit by administering sodium thiosulfate in addition to treatment with hydroxocobalamin.
  • Physical incompatibility (particle formation) and chemical incompatibility were observed with the mixture of hydroxocobalamin in solution with selected drugs that are frequently used in resuscitation efforts. Hydroxocobalamin is chemically incompatible with sodium thiosulfate or sodium nitrite. Therefore, these and other drugs should not be administered simultaneously through the same intravenous line as hydroxocobalamin. If a second line is unavailable thoroughly flush the single line prior to administering sodium thiosulfate or sodium nitrite.

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. If the victim is alert, asymptomatic, has a gag reflex, and it has not been done previously, 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 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).

• Link to Key Acute Care Adult Medications section
• Link to Key Acute Care Pediatric Medications section

† FDA approved for this indication

‡ Not FDA approved for this indication/Off-label use

* Fetal risk cannot be ruled out, see DailyMed for additional details

§ Category C, see DailyMed for additional details

If victims can walk, lead them out of the Hot/Warm Zones 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. Should there be a large number of casualties, and if decontamination resources permit, separate decontamination corridors should be established for ambulatory and non-ambulatory victims.

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.

• Link to Management of the Deceased

Personnel should continue to wear the same level of protection as required in the Hot/Warm Zones.

Link to Hot/Warm Zones - 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/Warm Zones. However, do not attempt resuscitation without a barrier.

Speed is critical. If the victim is symptomatic, immediately institute emergency life support measures including the use of a cyanide specific antidote (IOs can be placed utilizing a drill to enable acute administration of IV antidotes) as well as 100 % oxygen. Treatment should be given simultaneously with decontamination procedures. Quickly ensure that the victim has a patent airway. Maintain adequate circulation. Stabilize the cervical spine with a decontaminable collar and a backboard if trauma is suspected. Assist ventilation with a bag-valve-mask device equipped with a canister or air filter, if necessary. Direct pressure should be applied to control heavy bleeding, if present.

• Link to Basic and Advanced Life Support
• Link to Pediatric Basic and Acute Life Support
• Link to Key Acute Care Adult Medications section
• Link to Key Acute Care Pediatric Medications section
• Link to Primary and Secondary Survey

Administer antidotes if they are needed and have not been previously administered. If possible, a system should be employed to track antidotes administered.

Link to Treatment in the Hot/Warm Zones

Set up Considerations

• Use pictorial and written posted instructions for victims to self decon when able, use locale-appropriate multilingual signage.
• Double bag contaminated clothing etc. (place hearing aids, valuables in small bag). Place bag in container by showers.
• Victims who are able may assist with their own decontamination.
• Children and the elderly are at increased risk for hypothermia - provide warm showers, blankets.
• Privacy must be considered, if possible.
• The decontamination system should be designed for use in children of all ages, by parentless children, the non-ambulatory child, the child with special needs, and also allow families to stay together.
• Use step-by-step child friendly instructions that explain to the children and parents what they need to do, why they are doing it and what to expect.
• Take into consideration that infants when wet are slippery and will need a way to get them through the decontamination process - i.e. plastic buckets, car seats, stretchers...
• Designate a holding area and provide staff to support and supervise the children.
• Recommended age appropriate staffing ratios for untended children.
  • 1 adult to 4 infants
  • 1 adult to 10 preschool children
  • 1 adult to 20 school-age children

Washing Instructions

• If there will be significant delay to decontamination have the victims rinse off with water exposed skin surfaces and disrobe (disposable clothing kits should be available).
• Remove all clothing (at least down to their undergarments) and place the clothing in a labeled durable 6-mil polyethylene bag (removal of clothing, at least to the undergarment level will reduce victim's contamination by 85 %).
• With liquid agent exposure if clothes have been exposed to contamination, then extreme care must be taken when undressing to avoid transferring chemical agents to the skin - i.e. any clothing that has to be pulled over your head should be cut off instead of being pulled over your head.
• Cover all open wounds with plastic wrap prior to performing head to toe decontamination (particular attention should be made to open wounds because cyanide is readily absorbed through abraded skin).
• Flush the exposed skin and hair with plain water for 2 to 3 minutes then wash twice with mild soap. Rinse thoroughly with water. Be careful not to break the patient/victim's skin during the decontamination process.
• Caution - many people shower as they do it at home rather than conducting a rapid decontamination of their bodies. Too aggressive scrubbing can lead to further damage to skin and open wounds.
• 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.
• Utilizing large amounts of water by itself is very effective (limit pressure in infants).
• If water supplies are limited, and showers are not available an alternative form of decontamination is to use absorbent powders such as flour, talcum powder, or Fuller's earth (0.5% sodium hypochlorite solution is contraindicated).
• Sodium hypochlorite is not recommended for use in infants and young children.
• Certification of decontamination is accomplished by any of the following: processing through the decontamination facility; M256A1 chemical agent detector kit (liquid and vapor), M18A2, M90 chemical agent detectors (vapor)
• If still contaminated, repeat shower procedure.

Decontamination of First Responder:

• Begin washing PPE of the first responder using soap and water solution and a soft brush. Always move in a downward motion (from head to toe). Make sure to get into all areas, especially folds in the clothing. Wash and rinse (using cold or warm water) until the contaminant is thoroughly removed.
• Remove PPE by rolling downward (from head to toe) and avoid pulling PPE off over the head. Remove the SCBA after other PPE has been removed.
• Place all PPE in labeled durable 6-mil polyethylene bags.

Decontamination of Infants and Children

• Video: Decontamination of Infants and Children (HHS/AHRQ, Children's Hospital Boston) (Watch video)
  • Decontamination of Children (HHS/AHRQ) provides a step-by-step decontamination demonstration in real time, and trains clinicians about the nuances of treating infants and children, who require special attention during decontamination.

Wound Management

• Link to Wound Management

References

• Medical Management of Chemical Casualties Handbook, 2nd edition, September, 1995
• Braue EH, Boardman CH. Decontamination of Chemical Casualties
• Jagminas L. CBRNE - Chemical Decontamination (eMedicine)

Following decontamination, the patient should be reassessed; noting changes in triage category (if any), the need for or the modification of supportive therapy as well as the initiation or continuation of cyanide specific antidotes (See ABC reminders/Advanced Treatment) .

ABC Reminders

Quickly access airway patency. If trauma is suspected, maintain cervical immobilization manually and apply a cervical collar and a backboard when feasible. Ensure adequate respiration and pulse. Document oxygen saturation. Administer 100 % supplemental oxygen 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.

If the patient is symptomatic, immediately institute emergency life support measures, including the use of cyanide specific antidotes.

In cases of respiratory compromise, secure airway and respiration via endotracheal intubation or laryngeal mask airway (LMA).

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, 1 mEq/kg intravenous of sodium bicarbonate.

• Link to Basic and Advanced Life Support

When possible, treatment with cyanide antidotes should be given under medical supervision to unconscious victims who have known or strongly suspected cyanide poisoning. AMYL and SODIUM NITRITE have the potential to put the fetus of a pregnant woman at serious risk. In addition, there is increased vulnerability of infants and young children, those with active respiratory disease or diminished pulmonary reserve as well as those who have cardiovascular disease, particularly the elderly or frail, to increased methemoglobin levels (especially if combined with carbon monoxide exposure).

Therefore, initial treatment with hydroxocobalamin is recommended vs. amyl and sodium nitrite in pregnant women, infants, young children (especially with co-morbidities such as smoke inhalation).

• Cyanide antidotes - amyl nitrite‡* perles and intravenous infusions of sodium nitrite†§ and sodium thiosulfate†* - are packaged in the cyanide antidote kit.
  • Amyl nitrite perle should be broken onto a gauze pad and heal under the nose, placed under the lip of a facemask, or over the Ambu-valve intake. The patient should inhale for 30 seconds of each minute and a new perle should be utilized every three minutes if sodium nitrite infusions will be delayed. CAUTION IF AMYL NITRITE IS TAKEN WITH DRUGS LIKE VIAGRA, CIALIS, OR LEVITRA (OTHER NITRITE-CONTAINING DRUGS), A NEGATIVE INTERACTION CAN CAUSE FAINTING, A DROP IN BLOOD PRESSURE AND EVEN DEATH.
  • As soon as IV access has been achieved in a symptomatic patient DC the perles and initiate IV sodium nitrite (ASAP).
  • The usual adult dose is 10 ml of a 3 % solution (300 mg).
  • The pediatric dose is 0.12 to 0.33 ml/kg.
  • It should be infused over no less than 5 minutes (monitor BP frequently).
  • If hypotension develops, slow rate down. Consider giving crystalloids and vasopressors.
  • Obtain methemoglobin level 30 minutes after dose and consider possible methemoglobin formation if the patient deteriorates during therapy.
  • Follow-up immediately with IV sodium thiosulfate (12.5 grams infused over 10 - 20 minutes).
  • The adult dose is 50 ml of a 25 % solution.
  • The pediatric dose is 1.65 mL/kg of a 25 % solution.
  • Repeat one-half of the initial dose in 30 minutes if there is an inadequate clinical response or at 2 hours for prophylaxis.
  • IV sodium nitrite removes cyanide from the cells and subsequently binds with hemoglobin forming methemoglobin (which cuts down on the blood's ability to carry oxygen to the tissues). If the methemoglobin level is dangerously high (see below), one can give 1% methylene blue IV, which sends cyanide back to the cells, 1-2 mg/kg (0.1-0.2 mL/kg of a 1% solution), given very slowly over several minutes.
  • In patients who are not clinically responding you can measure the methemoglobin level (however this testing may seriously underestimate the levels of inactive hemoglobin) and utilize this as a therapeutic guide?
  • 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.
  • Methemoglobin levels should not exceed 20 - 30 % in children, 40 % in adults.
  • Repeat treatment with nitrite and thiosulfate as required.
    In animal studies, it has been documented that sodium thiosulfate does not cross the placenta when utilized to treat cyanide toxicity but by treating the mother the cyanide levels in the fetus were lowered.
• Hydroxocobalamin
  • A dose of 70 mg/kg (not to exceed 5 grams initially) administered over 15 minutes is recommended. This dose can be given IV push in situations of cyanide induced cardiac arrest. (Adult† Pediatric‡ Pregnancy§)
  • Depending upon the severity of the poisoning and the clinical response, a second dose of 70 mg/kg (not to exceed 5 g) may be administered by intravenous infusion for a total dose of 10 g. The rate of infusion for the second dose may range from 15 minutes (for patients in extremis) to two hours, as clinically indicated
  • Many patients with cyanide poisoning will be hypotensive; however, elevations in blood pressure have also been observed in known or suspected cyanide poisoning victims. Elevations in blood pressure (≥180 mmHg systolic or ≥110 mmHg diastolic) were observed in approximately 18% of healthy subjects (not exposed to cyanide) receiving hydroxocobalamin 5 g and 28% of subjects receiving 10 g. Increases in blood pressure were noted shortly after the infusions were started; the maximal increase in blood pressure was observed toward the end of the infusion. These elevations were generally transient and returned to baseline levels within 4 hours of dosing.
  • While a safe drug, animal and anecdotal human studies have demonstrated limited or no additional therapeutic benefit by administering sodium thiosulfate in addition to treatment with hydroxocobalamin.
  • Physical incompatibility (particle formation) and chemical incompatibility were observed with the mixture of hydroxocobalamin in solution with selected drugs that are frequently used in resuscitation efforts. Hydroxocobalamin is chemically incompatible with sodium thiosulfate or sodium nitrite. Therefore, these and other drugs should not be administered simultaneously through the same intravenous line as hydroxocobalamin. If a second line is unavailable thoroughly flush the single line prior to administering sodium thiosulfate or sodium nitrite.
  • Simultaneous administration of hydroxocobalamin and blood products (whole blood, packed red cells, platelet concentrate and/or fresh frozen plasma) through the same intravenous line is also not recommended. However, blood products and hydroxocobalamin can be administered simultaneously using separate intravenous lines (preferably on contralateral extremities, if peripheral lines are being used).
  
  

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. If the victim is alert, asymptomatic, has a gag reflex, and it has not been done previously, 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 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).

† FDA approved for this indication

‡ Not FDA approved for this indication/Off-label use

* Fetal risk cannot be ruled out, see DailyMed for additional details

§ Category C, see DailyMed for additional details

• Treat apnea, seizures, cardiac arrhythmias, shock, and pulmonary edema in the traditional way.
• Continuously monitor cardiac rhythm.
• If the patient's pH is < 7 or the patient is having significant dysrhythmias (which may be secondary to serious acidosis), treat with sodium bicarbonate.
• Treat complicating injuries or infections.
• Patients with histories of significant exposure should be hospitalized.
• Patients utilizing infusions from the cyanide kit should be admitted to the ICU.
• Patients who are asymptomatic 6 hours after exposure may be discharged with instructions to follow-up immediately if symptoms develop.
• 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.
  
  Link to Basic and Advanced Life Support

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.

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, 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.

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.

• Link to Surveillance for Possible Chemical Emergency
• Link to Management of the Deceased

Follow-up Instructions

• 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 _____________

Adapted from Medical Management Guidelines for Hydrogen Cyanide (ATSDR/CDC)

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