Hydrogen cyanide poisoning is poisoning that occurs through contact with prussic acid (cyanide) and can be fatal if even small amounts are ingested.
What is hydrogen cyanide poisoning?
Oral ingestion of as little as 70 mg of substances containing hydrogen cyanide can cause death from hydrogen cyanide poisoning. In some cases, a lethal effect is assumed from an intake of 1 to 2 mg of prussic acid per kilogram of body weight. Prussic acid is found in the seeds of some fruits. Hydrogen cyanide also develops when plastics are burned, for example in house or car fires. However, prussic acid poisoning can also occur with above-average frequency in the galvanoplastic industry. Furthermore, cases of hydrogen cyanide poisoning have occurred during medically indicated infusion of the drug nitropusside, which belongs to the cyanides. For hereditary reasons, about one third of all people cannot detect the odor of bitter almonds emanating from prussic acid. Foods and substances that may contain cyanide must therefore be handled very carefully because of the risk of prussic acid poisoning.
Causes
Hydrogen cyanide poisoning can be caused by skin contact, ingestion, or inhalation. The poisoning is caused by hydrogen cyanide, which blocks cellular respiration, causing “internal suffocation.” Hydrogen cyanide can (for example, after gas formation in smoldering fires) pass through the respiratory air via the lungs into the blood and surrounding tissue areas. Since hydrocyanic acid evaporates rapidly at normal room temperatures, cyanides quickly become airborne. Furthermore, hydrocyanic acid can penetrate the upper layers of skin without difficulty and thus enter the bloodstream. The absorption of hydrogen cyanide through the skin is favored during sweat-forming physical activity, since hydrogen cyanide is very soluble in water. Similarly, cyanide enters the bloodstream when food containing hydrogen cyanide is consumed, resulting in hydrogen cyanide poisoning.
Symptoms, complaints, and signs
When prussic acid poisoning is mentioned, it is usually thought of as acutely severe and always fatal. This is also the case when large amounts of hydrogen cyanide are inhaled. In these cases, severe respiratory distress, convulsions, vomiting and unconsciousness occur. The air breathed by those poisoned has a typical bitter almond odor. Death by suffocation occurs within a few seconds or minutes. After the fact, hydrocyanic acid poisoning can be detected by a bright red coloration of the dead person’s skin. The corpse stains appear bright red. For less severe concentrations of hydrocyanic acid, rapid treatment with cyanide-binding or cyanide-degrading agents can save lives. However, it is less well known that nonfatal acute hydrogen cyanide poisoning also occurs. There is little information on this in the medical literature. But even in these cases, the poisoning is initially manifested by shortness of breath, severe headache, dizziness, convulsions, vomiting, and possibly unconsciousness. After the end of the acute phase, however, neurological symptoms may develop. Thus, in individual cases, speech disorders, impaired memory, lack of energy, severe fatigue, disorientation, and general physical and mental deterioration occur. These disorders are very long-lasting and may persist forever, as the central nervous system and brain are often irreversibly damaged. However, it has also been noted that other organs are not usually affected.
Diagnosis and progression
The patient suffering from hydrogen cyanide poisoning experiences dizziness, vomiting, headache, and ringing in the ears. A typical symptom in hydrocyanic acid poisoning is that the sufferer breathes air smelling of bitter almonds. The hyperventilating sufferer goes into respiratory distress. In severe cases of poisoning, epileptic seizures occur. The sick person loses consciousness (after 26 minutes on average) and eventually suffers respiratory paralysis. If no treatment is given, death occurs within a very short time after ingestion of the toxins in the case of a high dose of poison. Since oxygen can no longer be processed by the body and therefore remains in the veins, the blood appears bright red, so that the mucous membranes and skin of the sick person show a pinkish tint. After a death due to hydrocyanic acid poisoning, typical bright red livid patches (livores) similar to poisoning by carbon monoxide therefore also appear.A definite diagnosis can usually only be made with the help of information from relatives or third persons (external history), since the affected person is usually no longer capable of providing appropriate information in the case of hydrogen cyanide poisoning.
Complications
Hydrogen cyanide poisoning is a very serious poisoning of the human body and it is imperative that it be treated by a physician. If hydrocyanic acid poisoning is not treated in time, permanent damage may occur in the patient. In the worst case, hydrogen cyanide poisoning leads to death. After prussic acid poisoning, the affected person usually first suffers from severe shortness of breath. This shortness of breath is accompanied by the typical odor of bitter almonds emanating from the patient’s breath. In addition, headache, dizziness, vomiting, fainting and convulsions occur. The skin color often turns pinkish. If the skin slowly turns pinkish or bright red, an emergency physician must be called urgently, as death will occur in this case. However, in the case of prussic acid poisoning with a relatively high concentration, the red coloration does not appear. If the prussic acid was inhaled, respiratory arrest and cardiac arrest will occur after only a few minutes. In this case, treatment is no longer possible. In the case of minor prussic acid poisoning, treatment with sulfur is administered to the body in addition. If only a small amount of hydrogen cyanide has been ingested, there is a relatively high chance that the patient will recover. With higher amounts, the probability is lower. The lethal dose for humans is 100 molecules of cyanide per million molecules of air.
When should you see a doctor?
If cyanide poisoning occurs, medical attention should be sought immediately. This is true even if the amount of the toxin ingested is very small. Great care should be taken, especially with children and pets, who are often poisoned by fruit or raw legumes. Prussic acid is not only found in the notorious bitter almonds. The pits of cherries and apples and the stones of plums, apricots and peaches also contain prussic acid. If there is a risk that a child or pet has swallowed such fruit components or eaten raw beans or raw peas straight from the bush, a doctor or veterinarian should be consulted immediately as a precaution. A doctor should also be consulted for elderly people and people in poor general health to prevent complications and late effects. Healthy adults should seek medical help at the latest when a dangerous amount of hydrogen cyanide has been consumed or the first symptoms of poisoning appear. The lethal dose in humans is about one gram per kilogram of body weight. However, even lower doses must be treated promptly. If the first symptoms of hydrogen cyanide poisoning appear, a doctor must be consulted immediately. Those affected initially suffer from nausea and vomiting, often accompanied by severe headaches and cramps. As soon as the patient shows a rosy skin color, there is acute danger to life from carbon monoxide poisoning. In this case, the emergency physician must be notified immediately.
Treatment and therapy
If hydrogen cyanide poisoning is feared, a physician must be consulted immediately. It depends on the extent of the poisoning whether the supply of fresh air is sufficient, ventilation must be given with the use of a respiratory mask, or even oxygen ventilation under positive pressure. Ventilation is then performed with 100 percent oxygen by introducing a tube into the respiratory organs. In order to exclude organ damage, this treatment is also carried out if the patient should be responsive again in the meantime. On the other hand, mouth-to-nose or mouth-to-mouth resuscitation must never be performed, as the rescuer would otherwise expose himself to the risk of prussic acid poisoning. As an antidote, the patient is administered a so-called antidote suitable for inactivating or reducing the effect of toxins, in particular sodium thiosulfate, 4-DMAP (4-dimethylaminophenol) or hydroxocobalamin, in order to convert the hydrocyanic acid into less dangerous thiocyanate, which can no longer lead to respiratory paralysis. If the symptoms of poisoning are only slight, for example, one to 3.25 mg of 4-DMAP per kilogram of body weight is administered, followed by the gradual administration of 10 grams of sodium thiosulfate. If the patient has consumed larger quantities of bitter almonds or if there is other oral ingestion of the poison, gastric lavage is performed.To remove hydrogen cyanide compounds from the body as quickly as possible, laxatives and large-pored activated charcoal, which is able to bind cyanides, are used.
Outlook and prognosis
The prognosis for cyanide poisoning is generally poor. The only form of cyanide poisoning that can be survived without treatment is that of very mild poisoning, which manifests itself in mild symptoms. Such a very mild poisoning can be survived by the affected person himself, since the body is able to break down the hydrogen cyanide in small quantities. In such cases, however, the general malaise is hardly perceived as poisoning. In the case of moderate and severe poisoning, on the other hand, death will inevitably occur through respiratory or cardiac arrest without treatment. Moderate poisoning can be combated in affected individuals by immediate emergency measures, which must be initiated within minutes of the onset of poisoning symptoms. The chances of surviving this without consequential damage are good with immediate help and detoxification. The limit here is often given as 30 minutes. On the other hand, severe cyanide poisoning, for example by direct inhalation, will be fatal even if relief measures are taken. Once the lethal dose has been reached or exceeded, detoxification measures will no longer help. Finally, the poisoning leads to death within a few minutes. Consequential damage only occurs if internal organs have been damaged as a result of the poisoning. This is not necessarily the case and depends, among other things, on how the cyanide was absorbed.
Prevention
Because very rapid treatment is required when hydrogen cyanide poisoning has occurred, all cyanide-processing companies, emergency ambulances, and clinics must be equipped at all times with sufficient antidote quantities to administer the antidotes at the very latest 30 minutes after poisoning has occurred. As a general rule, caution should be exercised when handling foods containing hydrocyanic acid, such as bitter almonds. In smoldering fires or car fires, remove all persons from the smoke zone as quickly as possible.
Aftercare
Hydrogen cyanide poisoning that is intentionally induced often exempts treating physicians from follow-up care. It is usually fatal. However, people often experience accidental hydrogen cyanide poisoning. Mild symptoms of poisoning can occur from eating bitter almonds or bitter apricot kernels. Hydrogen cyanide poisoning can also result from inhaled smoke from burning plastics or from working in the electroplating industry. It becomes dangerous because many people cannot detect the typical odor of hydrogen cyanide. In case of corresponding poisoning symptoms, medical treatment is necessary. Since it is an acute poisoning, neurological consequential damages are possible. These are subject to medical follow-up. Pregnant women should refrain from doing anything to prevent poisoning of the unborn child with small amounts of hydrocyanic acid from cyanide-containing foods as part of a comprehensive precautionary approach. Cancer patients who take amygdalin as a food supplement occasionally suffer hydrogen cyanide poisoning as a result. This leads to hospitalization and oncological follow-up. In the context of cancer therapy, amygdalin is often offered abroad as “vitamin B17″. However, this preparation is prohibited in Germany. The same applies to laetrile, which has a similar chemical structure. Anyone who obtains amygdalin illegally to supplement cancer therapy runs the risk. The conversion of the active ingredient in the intestine results in prussic acid poisoning. Follow-up care after prussic acid poisoning depends on the degree of poisoning symptoms and subsequent damage acquired as a result.
What you can do yourself
If prussic acid poisoning is suspected, first aid measures must be taken. The affected person must be taken out of the danger area immediately and provided with fresh air. In case of respiratory arrest, resuscitation by cardiopulmonary resuscitation must be performed immediately. Mouth-to-mouth resuscitation should be avoided due to the acute risk of poisoning. Until the rescue service arrives, the victim should be placed in the recovery position and, if possible, wrapped in a warm blanket. Constricting clothing must be opened or loosened. The emergency physician must be informed about the cause of the poisoning and the condition of the poisoned person by means of the W-questions in order to enable targeted treatment.Last, the cause of the poisoning should be determined and eliminated as soon as possible, if this can be done without further risk of poisoning. After the prussic acid poisoning has been cured, the affected person may need to use dietary measures to make up for lost nutrients and fluids (due to gastric lavage). Bed rest and sparing are also recommended. Because poisoning can result from even contact with the poisoned person, first responders should also seek emergency medical attention.
