Organophosphate poisoning

Overview

Organophosphates are a common class of insecticides. But large doses of organophosphates can also harm people and other animals. Organophosphate poisoning can occur when you’re exposed to them for too long or at high levels.

Organophosphates are typically colorless-to-brown liquids at room temperature. Some may be unscented, while others have a fruit-like smell.

Researchers say as many as 25 million agricultural workers across the developing world have at least one episode of organophosphate poisoning per year. It’s being seen with more frequency in areas where there is limited access to insecticide safety gear, such as suits and breathing apparatuses.

Terrorist use of organophosphates is rare, but it has occurred. Sarin, an organophosphate poison, has been intentionally used twice in terrorist attacks in Japan.

What are the symptoms of organophosphate poisoning?

Organophosphate poisoning can be short- or long-term. It can be caused by large or small doses. The longer the exposure and the larger the dose, the more toxic the effects. Symptoms can occur within several minutes or hours of exposure.

Mild organophosphate exposure may cause:

  • narrowed, pinpointed pupils
  • impaired, blurry vision
  • stinging eyes
  • runny nose
  • watery eyes
  • excess saliva
  • glassy eyes
  • headache
  • nausea
  • muscle weakness
  • muscle twitching
  • agitation

Moderate signs of organophosphate exposure include:

  • very narrowed pupils
  • dizziness
  • disorientation
  • coughing and wheezing
  • sneezing
  • difficulty breathing
  • drooling or excessive phlegm
  • muscle twitching and tremors
  • muscle weakness
  • fatigue
  • severe vomiting and diarrhea
  • involuntary urination and defecation

Emergency signs of organophosphate poisoning include:

  • very narrowed pupils
  • confusion
  • agitation
  • convulsions
  • excessive body secretions, including sweat, saliva, mucus, and tears
  • irregular heartbeat
  • collapse
  • respiratory depression or arrest
  • coma

What are the complications of organophosphate poisoning?

Organophosphate poisoning can cause several serious complications. These include:

  • metabolic disorders, such as hyperglycemia (high blood sugar) and glycosuria (excess sugar in urine)
  • diabetic ketoacidosis, in which your blood produces excess blood acids
  • pancreatitis, or inflammation of the pancreas
  • cancer
  • neurological problems, such as muscle weakness and twitching, poor concentration, poor memory, and post-traumatic stress disorder
  • fertility problems
  • paralysis

Complications tend to become worse the longer and more intensely you are exposed to organophosphates.

What causes organophosphate poisoning?

The people most at-risk for unintentional organophosphate poisoning are those who live or work on or near farms. You can also get organophosphate poisoning by consuming contaminated food or water. The most common unintentional exposure routes are through breathing and contact with the skin.

People who intentionally expose themselves to organophosphates tend to inhale and ingest it. These concentrated, high doses are often fatal.

How is organophosphate poisoning diagnosed?

If you suspect you were exposed to some type of harmful chemical, your doctor will work to determine which is affecting you. There are subtle differences between the effects of various types of poisons. Organophosphate poisoning is distinguished from other types of poisoning by a very fast onset of symptoms.

If you have symptoms of organophosphate poisoning, your doctor try to determine how severely you were exposed. They will do this through blood and urine tests.

How is organophosphate poisoning treated?

The first goal of treating emergency cases is stabilization. Emergency care workers will:

  • decontaminate your body to prevent further exposure
  • stabilize your breathing
  • use intravenous fluids to flush your system of toxins

In non-emergency cases, healthcare providers will still administer some supportive therapy. They’ll pay close attention to your breathing. Respiratory function is weakened by organophosphate exposure.

Doctors may administer a drug called atropine to stabilize your breathing. They may also administer pralidoxime, which can help relieve neuromuscular problems. In severe cases, doctors often prescribe benzodiazepines to prevent or stop seizures.

If you have been exposed to organophosphates in small doses and don’t need to be hospitalized, you may administer a low dose of atropine to yourself using a commercially prepared injection:

Age and weight Dose
adults and children who weigh more than 90 pounds (41 kilograms) 2 milligrams (mg)
children weighing 42 to 90 pounds (19 to 41 kilograms) 1 mg
children weighing less than 42 pounds (19 kilograms) 0.5 mg

An injection of 10 mg diazepam is recommended for people exposed to chemical attacks of organophosphates.

What’s the outlook for organophosphate poisoning?

Organophosphate poisoning is a serious medical condition, no matter how small the dose. Long, high-intensity exposures are the most concerning. See a doctor right away if you believe you’ve been exposed to organophosphate chemicals. Seek emergency treatment immediately if you’re displaying severe signs of poisoning.

Call 911 or seek emergency medical attention right away if you or someone you know has attempted suicide with organophosphates or any other method. If you or someone you know is thinking about suicide, call the National Suicide Prevention Lifeline at 1-800-273-8255. If you can safely prevent a person from attempting suicide, do so and take them to a hospital right away.

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Feature cluster Likely poison
Small pupil, slow breathing,
unconsciousness, weak pulse ,
hypothermia and vomiting.
opioid
...What are different types of
organophosphorus compounds?
 They can be classified as three categories:
A. Derivatives of phosphoric (H3PO4), phosphorus
(H3PO3) & phosphinic acid (H3...• Nerve agents
• Insecticides
• Glaucoma treatments
• Myasthenia gravis
• Potential uses in alzheimer’s disease and dement... How phosphates are different
from Carbamates
 Organophosphates vs. Carbamates
Organophosphates Carbamates
Cholinesterase Non-reversible reversible
Symptoms Vomiting, di...1. Cutaneous
2. Ingestion
3. Inhalation
4. Injection
14
 • Inhibit acetylcholine esterase
enzyme at nerve endings by
phosphorylation
↑ acetylcholine at receptor sites
Mechanism of...Diarrhea Salivation
Urination Lacrimation
Miosis Urination
Bradycardia Defecation
Bronchospasm G.I upset
Emesis Emesis
Lac...How do you grade the severity??
 GRADE SYMPTOMS
MILD NAUSEA, VOMITING
DIARRHOEA
SWEATING
MODERATE LACRIMATION, SALIVATION
MIOSIS
FASCICULATION
SEVERE INCON...How long will it take to present with
toxidromes??
  Generally oral or respiratory exposures
within three hours.
 While from dermal absorption may be
delayed up to 12 hours.
 How will you confirm your
diagnosis??
  88% of patients initially deny any exposure history.
 Petroleum or garlic-like odor.
 If doubt exists a trial of atrop...1. Butyrylcholinesterase activity in plasma
2. Acetylcholinesterase in whole blood
3. Other
1. CXR - Evaluate pulmonary oe...Which enzyme assays correlate
more with poisoning severity??
 Red cell acetylcholinesterase inhibition is a good
marker of severity
 Red cell ACEs ≥ 30% - normal muscle function,
no a...Plasma butyrylcholinesterase activity does not
relate to severity of poisoning
 More easily performed
 A depression of 2...These enzymes facilitate the decision
about
 When to stop oxime and
 Allow cautious weaning of a patient
 Cholinergic/ OP poisoning
 How will you manage..???
 1. Check airway, breathing, circulation.
2. Monitor Vitals and cardiac rhythm
3. Look for signs & symptoms
4. Obtain IV ac...6. Atropine intravenously as soon as possible for
symptomatic patient
7. Pralidoxime (Reactivator)
8. Gastric lavage once ... Wash at least 3 times with soap (containing
chlorhexidine and alcohol) and water, paying
particular attention to hair, s... Gastric lavage decreases absorption by 42% if
done within 20 min
 By 16% if performed at 60 min
 Choice of fluid is ta... Lateral position better - delays spont.
Absorption
 No evidence that larger tube better
 Preferably done on awake pati... Start with 1.8-3.0 mg fast iv bolus
 After 3-5minutes check
1. Bronchorroea & bronchospasm
2. Bradycardia ( <60 )
3. Mi...1. Clear chest on auscultation with no wheeze
2. Heart rate >80 beats/min
3. Pupils no longer pinpoint
4. Dry axillae
5. S... D5 + 10-20% of the total initial dose of
atropine on an hourly basis. (after
stabilization)
 STOP atropine infusion if ... Confusion, delirium, coma
 Urinary retention, Bowel ileus
 Hyperthermia
 Agitation, psychosis
 Flushing
 Tachycardi... loading dose @ 30mg/kg IV over 10-20mins
 Continuous infusion of 8-10mg/kg/hr.
 Upto when??
  Continue oxime infusion until atropine has
not been needed for 12–24 h and patient
extubated
 What are the different phases of
toxicity..?
 1. Acute cholinergic crisis
2. Intermediate syndrome (IMS)—major cause
of morbidity and mortality
3. Delayed neuropathy
  Excess acetylcholine at NMJ causes downregulation
of nicotinic receptors- muscles affected
 Inadequate oxime therapy,
... C/F typically occur within 24 to 96 hours &
persists for 4-18 days
 Affecting conscious patients without cholinergic
si... Assess flexor neck strength regularly (head
lift & hold against resistance)
 Weakness is a sign of peripheral respirato...1. Organophosphate induced delayed neuropathy
(OPIDN)
o 2-3 weeks after large dose
oPeripheral/distal neuropathy (proximal...1. Extrapyramidal manifestations- Dystonia, resting
tremor, rigidity, chorea
2. Neuro-ophthalmic manifestations- Optic
neu... Prophylactic diazepam shown to decrease
neurocognitive dysfunction after poisoning.
 Diazepam 0.1-0.2 mg/kg IV, repeat ...FRUSEMIDE – for persistent pulmonary
oedema after full atropinization.
  Magnesium
 Reduces acetylcholine release
 Block pre-synaptic calcium channel
 Clonidine
 Decrease the presynaptic sy... Respiratory
 Airway protection
 Respiratory failure
 Cardiovascular
 Hypotension despite fluid challenge
 Heart blo... Neurologic
 GCS < 8
 Seizures
 Metabolic
 Hypoglycaemia
 Significant electrolyte abnormalities
 metabolic acidosis...What are commonly used nerve
agent antidote kits?
  It is a dual chamber autoinjector
1. Atropine sulfate and
2. Pralidoxime
 Only effective against the nerve agents tabun... A newer model, the ATNAA (Antidote
Treatment Nerve Agent Auto-Injector),[1]
 Has atropine and the pralidoxime in one
sy...Signs &
Symptoms
Atropine Dose 2-PAM Dose
Severe Respiratory
Distress,
Agitation
3 Auto-injectors (6
mg)
Monitor every 5
m...Read the label before
selecting and applying
any pesticide.
 Organophosphorus poisoningOrganophosphorus poisoning

 

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Organophosphate poisoning

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