There has been a report, on May 4, of a stolen truck, from Union County, containing a substantial amount of potassium cyanide. It is unknown whether the cyanide was the intention of the theft or an accidental accompaniment. If the cyanide is released, there is a possibility of injury to the public. It is incumbent upon us to be alert to the possibility and prepare for victims. This is a briefing intended for distribution to health care providers in New Jersey Hospitals. Please be sure that all individuals in the role of triage or care of emergency department patients are aware of this event and the contents of this briefing paper. If you have any questions, do not hesitate to call the poison center at 1-800-764-7661!

Background: Cyanide is used in several industries. It is a precursor for some pesticides, is sometimes used as a fumigant, in printing, photography, in the manufacturing of paper and plastics, in mining of precious metal ores, and in the electroplating industry. Over 300,000 tons of cyanide are produced each year. Cyanogenic substances are also found naturally in the pits of some plants. An oral lethal dose of potassium cyanide is in the range of 200 mg in an adult, an airborne concentration of 270 ppm is immediately fatal and a concentration of 110 ppm for 30 minutes is considered life-threatening.

Toxicokinetics: Cyanide salts are rapidly absorbed by inhalation, ingestion and percutaneous routes. It is widely distributed in the body with a wide volume of distribution. It reacts with various systems in the body, prinicipally the cytochrome system, rendering electron transport inactive. It is excreted unchanged in the exhaled breath, saliva, sweat and urine; metabolized to thiocyanate and cyanocobalamine in the urine.

Pathogenesis: Cyanide interrupts the cytochrome system, thus prevents electron transport. This in turn blocks the production of ATP and interferes with all processes dependent on ATP, this changes metabolism to anerobic with resultant lactic acidosis with a large anion gap.. It blocks the extraction of O₂ from hemoglobin producing tissue anoxia without hypoxemia.

Clinical Effects: There is no single pathognomonic symptom or sign!

Respiratory: initially there is intense stimulation of receptors because of tissue hypoxia with resultant increase in respiratory effort and rate

Cardiac: initially there is stimulation of adrenal medulla with resultant tachycardia and hypertension, followed by hypotension and cardiac arrythmias and congestive failure

CNS: depending on concentration, headache, anxiety, confusion, lethargy, depending on concentration rapid loss of consciousness, convulsions, opisthotonus, decerebration and death from respiratory arrest

Skin: initially there may be flushing and diaphoresis, cyanosis is unusual early due to the lack of extraction of O₂ from the RBC and, thus, lack of hypoxemia. There may be a loss of the a/v _pO₂ difference

Metabolic: the accumulation of lactic acid leads profound metabolic acidosis resistant to alkali therapy.

Gastrointestinal: Nausea and vomiting are common.

Odors: cyanide salts are said to smell like bitter almonds, a substantial portion of the population, however, are congenitally unable to appreciate the smell, thus it may not be a dependable indication of exposure.

CONSIDER THE DIAGNOSIS!

• Sudden collapse of victim(s).
• The presence of a resistant metabolic acidosis and or severe hypotension unresponsive to usual therapy in an individual with normal color or normal arterial _pO₂ should suggest the diagnosis!
• Venous _pO₂>50 mm Hg.
• Differential diagnosis must include carbon monoxide exposure since the treatment for cyanide may increase the severity of illness in cases of carbon monoxide intoxication.
• Reports of dead insects, animals, unusual smells in an unusual location

Direct immediate attention to the usual A, B, C's! It is important to protect the rescuers as well, vomitus may contain active substance which can be dangerous to those in contact. Rescue breathing by mouth to mouth has resulted in symptom production in the rescuer when the victim has ingested cyanide salts.

It is imperative that a presumptive diagnosis is made rapidly and treatment instituted with no delay. All hospitals should have the "Lilly Cyanide Antidote Kit" in stock in their emergency department. It is important that the expiration date be checked and appropriate replacement made when necessary, The kit includes 3 parts: pearlettes of amyl nitrite, a vial of sodium nitrite and a vial of sodium thiosulfate. The efficacy of the kit is suspect but is the current standard of care.

Oxygen: high flow, 100 % oxygen, should be administered immediately. Limited data suggests that hyperbaric oxygen treatment may be beneficial!

Amyl nitrite: if the patient is conscious and breathing, have him/her inhale deeply from a crushed pearlette. If the patient is unconscious and not breathing on his/her own, crush the pearlette and place it in the mask and bag-and-mask ventilate him/her until adequate intubation and iv line access has been accomplished.

Sodium nitrite: the standard has been to induce methemoglobinemia with sodium nitrite to cause the release of cyanide from the cytochromes involved and production of cyanomethemoglobinemia and thus regenerating the cytochrome system. It is important to rule out the possibility of carbon monoxide since the production of methemoglobinemia in a victim of carbon monoxide will further decrease the transport of oxygen to the tissues and produce an even greater tissue anoxia. The adult dose is 10 ml (300 mg) of a 35 solution administered over 15-20 minutes intravenously (in a child the dose is dependent upon both weight and hemoglobin concentration ranging from 5.8 mg/kg (019 ml/kg) in a child with a hemoglobin of 7, to 11.6 mg/kg (0.39 ml/kg) in a child with a hemoglobin of 14.

Sodium thiosulfate: this substance provides sulfur to allow the conversion of cyanide to thiocyanate by the enzyme rhodanese and allow excretion through the kidneys. In the absence of renal failure, thiosulfate is benign. The adult dose, of the usual 25% solution, is 50 ml (12.5 g) IV, and 1.65 ml/kg IV in a child.

Report all suspected cases to the local law enforcement agency!

When in doubt CALL NJPIES at 1-800-764-7661!!