Master List of Poisonous Plants

Hemlock (Cicuta)

Hemlock/Cicuta

Info about plant- 

All members of Cicuta except C. bulbifera contain high levels of the poisonous principle cicutoxin, an unsaturated aliphatic alcohol that is structurally closely related to the toxin oenanthotoxin found in the plant hemlock water dropwort. Its primary toxic effect is to act as a stimulant in the central nervous system. It is a non-competitive gamma-aminobutyric acid (GABA) receptor antagonist.

The exact toxic dose of plant material in humans is unknown; it is thought ingestion of water hemlock in any quantity can result in poisoning and very small amounts may lead to death. Intoxication has also been reported following skin contact with the plant; a case was reported where a family of five people rubbed the plant onto the skin and were poisoned, with two children dying. Roots exposed by ploughing can also be the source of livestock poisonings Ingestion of plant material may cause death in the animal in as little as 15 minutes

Symptoms

The onset of symptoms following ingestion may be as soon as 15 minutes post ingestion.

· Nausea

· Seizures

· vomiting,

· abdominal pain

· tremors, confusion

· Weakness

· dizziness

· drowsiness

Complications of ongoing seizure activity include-

· increased body temperature

· decreases in the pH of the blood (metabolic acidosis)

· swelling in the brain

· blood coagulation disorders

· muscle breakdown (rhabdomyolysis)

· kidney failure.

Additional neurological symptoms may include-

· Hallucinations

· Delirium

· Tingling

· Pricking or numbness of a person's skin

· dilated pupils

· coma.

Cardiovascular symptoms include-

· alternating slow or fast heart rate

· alternating low and high blood pressure.

Other cardiac effects may include-

· ECG (Electrocardiography) abnormalities such as widening of the PR interval supraventricular tachycardia

· ventricular fibrillation.

Symptoms of excess salivation, wheezing, respiratory distress, and absence of breathing have also been reported.

>Deaths usually occur from respiratory failure or ventricular fibrillation secondary to ongoing seizure activity; fatalities have occurred within a few hours of ingestion.<

Poisoned people who recover usually regain consciousness and seizures cease within 24 to 48 hours of poisoning, although seizures may persist for up to 96 hours. There are occasional long-term effects such as retrograde amnesia of the events leading to intoxication and the intoxication itself. Other ongoing mild effects may include restlessness, muscle weakness, twitching, and anxiety. Complete resolution of symptoms may take a number of days or, in some cases, these ongoing symptoms may persist for months after poisoning.

Diagnosis and treatment

Water hemlock poisoning is usually diagnosed following a history of plant ingestion and symptoms of the abrupt onset of seizures. Laboratory tests to determine the presence of cicutoxin in the blood such as spectrofluorimetric, high-pressure liquid chromatography, thin layer chromatography, and mass spectrometry have been used to detect cicutoxin but these tests are not performed routinely in hospital laboratories. If a sample of the plant ingested has been retained, diagnosis can be confirmed by having the plant identified by a botanist.

Initial treatment of poisoning may include gastrointestinal decontamination with activated charcoal. There is no specific antidote for water hemlock poisoning and treatment mainly consists of supportive care. Treatment may include control of seizures with the administration of a benzodiazepines such as lorazepam or diazepam, or if seizures are refractory to this treatment, a barbiturate such as phenobarbital is administered. The anticonvulsant phenytoin is not recommended as it has not been shown to be effective for seizure control following water hemlock poisoning. Treatment with high doses of benzodiazepines or barbiturates may cause respiratory depression and respiratory support including intubation and mechanical ventilation is required in these patients. Continuous electroencephalography monitoring is recommended in symptomatic patients.

Further treatment for complications of metabolic acidosis, rhabdomyolysis, hyperthermia, or low blood pressure may be required. Metabolic acidosis is treated by administering sodium bicarbonate. Low blood pressure is usually treated with intravenous fluid replacement, but the administration of dopamine or norepinephrine may be required to restore blood pressure. The management of rhabdomyolysis includes ensuring adequate hydration and urinary alkalization; a complication of rhabdomyolysis is an acute renal failure which may require management with hemodialysis. However, hemodialysis, hemoperfusion or other extracorporeal techniques do not remove cicutoxin from the blood and are therefore not useful in enhancing elimination.