What is Cyanide Toxicity?
Cyanide is a substance commonly known as a poison that acts quickly once ingested. It was first discovered in the Prussian blue dye as hydrogen cyanide in 1786, and later extracted from almonds around 1800. Cyanide can come in several forms, such as a gas named hydrogen cyanide, or a salt form, like potassium cyanide.
You can also find cyanide naturally in certain foods like lima beans and almonds. It is used in various industrial and manufacturing processes including insecticides, photography solutions, and jewelry cleaning.
Sadly, its lethal property made it a choice for mass murders and suicides. A grim example in history is its use by the Nazis as a killing agent in the gas chambers during World War II.
What Causes Cyanide Toxicity?
Cyanide poisoning can occur from various sources including house fires, workplace accidents, certain medications like sodium nitroprusside, and even some foods. In countries like ours, house fires are the most usual cause of cyanide poisoning. Moreover, cyanide is used in many industries such as metal plating, photography, plastic and rubber production, and in pesticides.
Sodium nitroprusside, a drug used during extremely high blood pressure situations, contains a lot of cyanide – five cyanide groups in every molecule to be exact. This means that patients who are given extended doses of sodium nitroprusside can end up with harmful cyanide levels in their bodies.
Risk Factors and Frequency for Cyanide Toxicity
Cyanide exposure is an issue humans face, with the Toxic Exposure Surveillance System recording over 3,165 exposures from 1993 to 2002. However, only a small portion of these exposures, 2.5%, resulted in death. In developed countries like the United States, fire is the leading cause of cyanide exposure. It’s estimated that around 35% of all fire victims end up with toxic levels of cyanide in their blood when they seek medical assistance.
- From 1993 to 2002, there were over 3,165 cases of cyanide exposure.
- 2.5% of these exposures led to death.
- Fire is the most common cause of cyanide exposure in developed countries.
- About 35% of fire victims have toxic levels of cyanide in their blood.
- In 2007, the National Poison Data System reported 247 cases of cyanide exposure, with five ending in fatalities.
Signs and Symptoms of Cyanide Toxicity
Exposure to cyanide can result in symptoms appearing within a minute if inhaled or after a few minutes if ingested. A bitter almond-like smell might be noticed, but only around 60% of people are able to pick up this scent. The symptoms tend to appear in early and late stages, affecting various body systems.
- Early symptoms affecting the brain can include headaches, dizziness, confusion, and dilated pupils. If not treated, these could lead to seizures or coma due to a lack of oxygen reaching the body’s tissues.
- Initial reactions in both the respiratory and cardiovascular systems involve faster breathing and heart rate. As time progresses, these can develop into apnea (disrupted breathing), low blood pressure, and irregular heart rate.
- Despite the lack of oxygen to the body’s tissues, the patient’s skin may appear normal or slightly pale.
- Interestingly, instead of appearing blue (cyanotic), patients with cyanide poisoning often have bright red-colored skin because of an excess amount of oxygen in their blood.
Testing for Cyanide Toxicity
When a patient is suspected of cyanide poisoning, a variety of lab tests are done initially. These tests include a complete blood count, electrolytes test, urine analysis, urine toxicology screen, arterial blood gas analysis, carboxyhemoglobin level (especially for people in a fire), chest x-ray, and an electrocardiogram (EKG). There’s also the plasma lactate test, where a level above eight mmol/L can be a strong indicator (94% sensitive and 70% specific) of significant cyanide toxicity.
If the patient was present in a structural fire, doctors assume they have cyanide toxicity. To rule out the possibility of other substances in the patient’s system, acetaminophen and salicylate levels might also be checked. An increased gap in metabolic acidosis is common in cyanide poisoning, so this would be expected in the patient’s results. In situations where people might have inhaled a lot of smoke, like in a fire, the carboxyhemoglobin level is especially important to check.
Although cyanide concentration levels can be obtained, they usually aren’t available in time to be useful during treatment. These results can also sometimes be unreliable because the blood needs to be drawn promptly and stored correctly. So, doctors mainly have to depend on the patient’s symptoms and general health.
Treatment Options for Cyanide Toxicity
In the case of cyanide poisoning, the healthcare provider must prioritize the patient’s breathing, stabilize their airway, and maintain blood circulation. Importantly, mouth-to-mouth resuscitation is not advisable due to potential risk to the person performing the CPR.
In treating cyanide exposure through skin or inhalation, the first step is decontamination. The patient needs to be moved away from the exposure source, and any contaminated clothing should be properly removed and discarded. Immediate administration of gastrointestinal decontamination is also crucial. Despite lab findings suggesting that activated charcoal binds poorly to cyanide, animal studies indicate that it actually can reduce death rates. So, a single dose of activated charcoal is recommended: 50g for adults and 1g per kg of body weight (up to 50g) for children.
If a person is thought to have cyanide poisoning and there are no reasons not to, antidotes should be given as soon as possible. The preferred antidote is Hydroxycobalamin – particularly for those who may also have carbon monoxide poisoning. This treatment is preferable as other antidotes can interrupt the body’s oxygen-carrying abilities and worsen certain health conditions. The typical dose is 5 grams, given intravenously over a 15-minute period. It’s worth noting that this treatment can turn urine a dark red color, but this shouldn’t be mistaken for another serious condition, myoglobinuria.
If Hydroxocobalamin is not accessible, a cyanide antidote kit can be used as a substitute. The kits typically contain sodium nitrite and sodium thiosulfate. They are administered intravenously – the specific dosage guidelines differ for adults and children.
The use of hyperbaric oxygen treatment – saturating the body with pure oxygen under high pressure – is disputed as research has provided inconsistent results. Some animal studies have suggested that it may enhance the effects of the primary antidotal therapy.
What else can Cyanide Toxicity be?
The main diagnosis to consider could be inhalation of carbon monoxide. If only exposed to this gas, patients usually get better once they’re out of the smoky area and given pure oxygen. In contrast to cyanide poisoning where people often experience seizures and pupil dilation, carbon monoxide exposure typically doesn’t cause these reactions.
Other substances that could cause similar symptoms like seizures, lowered blood pressure, altered consciousness, and increased lactic acid levels include tricyclic antidepressants, isoniazid, organophosphates, and salicylates. These are important to consider if a patient shows these signs.
What to expect with Cyanide Toxicity
Cyanide is an extremely dangerous poison that can cause death quickly. Depending on the situation, a person exposed to cyanide could die within minutes to a few hours. Because of this, swift medical attention is crucial for anyone who comes into contact with this substance.
Possible Complications When Diagnosed with Cyanide Toxicity
It’s crucial to diagnose cyanide toxicity early, as treatment is most effective at this stage. Failure to diagnose swiftly could lead to serious consequences. Survivors of severe cyanide poisoning could experience neurological problems such as Parkinson’s disease. This is because parts of the brain, known as the basal ganglia, are particularly vulnerable to the damaging effects of cyanide. Long-term exposure to cyanide, even at lower levels, can cause well-known symptoms that may be mistaken for other conditions. These include headaches, unusual taste sensations, vomiting, chest pain, and anxiety.
These symptoms can include:
- Headaches
- Unusual taste
- Vomiting
- Chest pain
- Anxiety
Preventing Cyanide Toxicity
All homes should have smoke alarms installed. This can help alert residents to potential fires and improve safety.
Additionally, workplaces should include education about cyanide toxicity and ways to prevent it. This can help ensure the safety and well-being of the workers.