Poisoning

16th July 2016 revised 17th March 2021

The dose makes the poison.

“All things are poison, and nothing is without poison; the dosage alone makes it so a thing is not a poison."

Paracelsus - the God Father of Toxicology

A Poison is any substance that can cause harm to the body. As Paracelsus, the 16th century physician proclaimed it is the dose that makes the poison.

Any substance is poisonous in sufficient quantities, including oxygen, water and other substances which are generally regarded as necessary for sustaining life.

Therefore, given that every substance on Earth has the potential to be a poison, rather than examine every possible poison a more pragmatic approach would be to examine the routes to poisoning, as this may alert you to potential dangers to yourself as well as to how you treat the casualty.


Route of Entry

Poisons can enter the body through a number of different pathways:

Route Description Possible Evidence Specific management
Ingestion Swallowing the poison is a common route; this is typically accidental rather than purposeful and can be caused by drinking an unidentified substance, for example, or by cross-contamination of a product from the casualty’s fingers to their lips. • Residue around the mouth and lips.
• Frothing at the mouth.
• Burns to the lips or tongue.		 • DO NOT induce vomiting.
• Sips of water are permitted to cool burns to the mouth.
• Use a BVM or perform compression-only CPR to prevent mouth-to-mouth contamination during resuscitation.
Inhalation Some poisons are airborne, which means they may not be visible and this presents the greatest risk to the rescuer as you may enter a noxious environment in an attempt to rescue the casualty. • Soot or residue around the nostrils.
• Difficulty breathing.
• Hoarse voice.
• Multiple casualties without any obvious mechanism.		 • Extract the casualty from the environment ONLY if it is safe to do so.
• Turn on extraction systems or open windows for ventilation.
• Use a BVM or perform compression-only CPR to prevent mouth-to-mouth contamination during resuscitation.
Injection Injection is where the poison has entered the body through a break in the continuity of the skin, be that a wound from a rusty saw, an accidental sharps injury, insect stings or an animal bite.
As the skin offers some level of protection against poisons entering the body, these poisons may not necessarily present an issue if they were applied to undamaged skin.		 • Puncture wound.
• Localised pain.
• Tracking – a red line progressing up the limb		 • Clean the wound to remove surface contaminants.
Absorption Some poisons, such as mercury and hydrofluoric acid can enter the body through the skin, without any break in continuity. Due to the danger of these poisons which can affect the casualty merely by contact, these chemicals are usually tightly controlled. • Local wound, rash or burn at the site of absorption.
• Pain		 • Thoroughly irrigate the area with copious amounts of water to remove surface contaminants.

• Hydrofloric acid burns should be treated with calcium gluconate gel.

• Diphoterine can be used on other contaminants - this will not reverse the affects of the poisoning but may reduce the liklihood of cross contamination.
Instilled Instilled poisons can enter the body through the mucous membrane surrounding the eyes. As this membrane is highly absorbent, poisons that would not normally enter the body through contact with the skin may enter the body through this route. • Red, watery eyes.
• Pain.		 • Thoroughly irrigate the eyes with clean water.
• Consider using a nasal cannula for a more tolerable experience for the casualty and more effective use of limited supplies clean water.
Nasal Cannula used for eye irrigation - read more here.

Nasal Cannula used for eye irrigation - read more here.

Signs & Symptoms

With the exceptions of a few notable cases, most poisons lead to non-specific signs and symptoms which are characteristic of general malaise:

  • Nausea / vomiting

  • Headache and / or dizziness

  • Reduced level of response

  • Possible abdominal pain - especially with ingested poisons

  • Potential change in skin colour

  • Potential difficulty breathing

Overall the casualty may simply appear…..unwell. This makes a diagnosis without a history or Mechanism of Injury almost impossible so the gathering of evidence using SAMPLE is particularly important.

Other sources of evidence:

  • Containers near the casualty or where they were.

  • Spilled substances, including liquids and powders.

  • High-risk work environments e.g. laboratories, refineries or certain manufacturing plants

  • High-risk activities e.g. using cleaning products, fertilizers or pesticides.

Gas Monitors

Inhaled poisons are difficult to detect; some gases, such as LPG used for cooking and heating in homes, are odourless so a stenching agent, methanthiol in the case of LPG, is added to make it detectable.

H2S BW Clip Monitor.jpg

Hydrogen Sulfide (H2S) - commonly found in oil drilling and refining sites - is only detectable by smell at low concentration and for a short period of time, typically described as ‘rotten eggs’, but continual exposure causes olfactory desensitization meaning it can no longer be smelled. At high concentration olfactory desensitization is instantaneous. Where there is a risk of H2S, Carbon Monoxide or combustibles, a gas monitor should be worn.

Where a collapsed casualty is found with no obvious mechanism of injury but is wearing a Gas Monitor, protective respiratory equipment or any other form of PPE, one should have a high suspicion of poisoning.

Safety Data Sheet
In a work environment, hazardous materials should come with a Safety Data Sheet (SDS) which provides additional information about the material. Notably, on all SDS paperwork, Section 4 contains First Aid advice which may be specific to the product. Seek out the SDS and transport it with the casualty to hospital.

Common Poisons
Poison Signs & Symptoms Description
Alcohol ● Nausea.
● Vomiting
● Reduced Level of response
● Convulsions
● Unconsciousness.		 Alcohol intoxication is a common emergency, and is usually a transient problem. However, when combined with drugs in overdose, it may pose a major problem. When combined with opiate drugs or sedatives, it will further decrease the level of consciousness and increase the risk of aspiration of vomit. In combination with paracetamol it increases the risk to the liver.

Remember to check the blood glucose levels especially in children and young adults who are ‘drunk’, as hypoglycaemia (blood glucose <4.0mmol/l) is common and requires treatment with oral glucose.
Carbon Monoxide ● Reduced Level of Response
● Dizziness
● Nausea
● Tiredness and confusion
● Abdominal pain
● Shortness of breath
● Difficulty breathing
● Unconsciousness.		 Carbon monoxide poisons the casualty by binding to the haemoglobin (red blood cells) before the oxygen has a chance to bind. With the haemoglobin bound with carbon monoxide, there is nowhere to which the oxygen can bind so the oxygen remains, unused, in the blood and the carbon monoxide is transported around the body to the cells instead.

Any patient found unconscious or disorientated in an enclosed space, for example, a patient involved in a fire in a confined space, where ventilation is impaired, or a heating boiler may be defective, should be considered at risk. The cherry-red skin colouration in carbon monoxide poisoning is, in fact, rarely seen in practice.(1)

Remove the patient from the source and administer 100% oxygen as carbon monoxide is displaced from haemoglobin more rapidly the higher the concentration of oxygen. This must be given continuously.

SpO2 monitoring is not reliable for a casualty poisoned by CO as the pulse oximeter measures bound haemoglobin, regardless of whether the haemoglobin is bound to oxygen or carbon monoxide.
Cyanide ● Confusion
● Drowsiness
● Reduced level of response
● Dizziness
● Headache
● Convulsions.		 Cyanide poisoning can occur in casualties exposed to smoke in a confined space (for example a house fire) or certain industrial settings where cyanide kits should be available and the kit should be taken to hospital with the patient.

Cyanide poisoning requires specific treatment – seek medical advice.

Provide full supportive therapy and transfer immediately to hospital.
Opiates ● Awake but non-verbal
● Limp body
● Pale skin
● Finger nails and lips become dark blue / purple
● Reduction in breathing effort
● Unconsciousness.		 Natural opiates such as Morphine, Heroin (Diamorphine and Codeine) and synthetic Opiates ( called 'Opioids' such as Methadone and Pethadine) are strong analgesics which are nervous system depressants.

Accidental overdose is common and results in classically a reduced level of resposne with slow, weak breathing and pulse (although pulse is, at this stage very difficult to detect).

Naloxone is a Prescription Only Medication that reverses the effects of Opiate overdose. It is available in several forms including Narcan and Nyxoid nasal sprays which are safe and esay to use.
Paracetamol ● Nausea
● Vomiting
● Malaise
● Right, upper quadrant abdominal pain
● Jaundice
● Confusion
● Drowsiness
● Unconsciousness.		 Even modest doses may induce severe liver and kidney damage. It frequently takes 24 to 48 hours for the effects of paracetamol damage to become apparent and urgent blood levels are required to assess the patient’s level of risk.
Tricyclic antidepressants ● Excitability
● Confusion
● Blurred vision
● Dry mouth
● Fever
● Pupil dilation
● Convulsion
● Reduced level of response
● Low blood pressure
● Respiratory distress.		 Poisoning with these drugs such as Desipramine (Norpramin), Doxepin, Imipramine (Tofranil) and Nortriptyline (Pamelor) may cause impaired consciousness, profound hypotension and cardiac arrhythmias. They are a common treatment for patients who are already depressed.

Newer anti-depressants such as fluoxetine (Prozac) and paroxetine (Seroxat) have different effects.

Monitor the casualty closely as the patient’s condition may change rapidly.

Treatment - Single Casualty

1. Ensure Scene Safety

2. Gather evidence

  • Assess the Casualty using SAMPLE to rule out medical conditions

    • What happened?

    • When did it happen?

    • What is the suspected substance?

    • What is the estimated quantity?

    • Has the casualty received any treatment so far?

    • Is there a known route to the poisoning?

3. Assess Airway and Breathing

  • Correct any airway issues and if the casualty’s breathing is not normal, immediately request Emergency Medical Services (EMS).

  • Provide high flow oxygen to maintain an Sp02 of 94-98%.

  • Consider ventilatory support using a Bag Valve Mask, if Sp02 remains below 90%.

  • In the case of cardiac arrest, utilize a BVM or restrict resuscitation to Compress-Only CPR. Avoid mouth-to-mouth resuscitation especially in suspected cases of inhaled or ingested poisoning.

  • Known opiate overdoses should be treated with Naloxone nasal spray:

    • If the patient does not respond, the second dose should be administered after 2-3 minutes.

    • If the patient responds to the first administration but then relapses again into respiratory depression, the second dose should be administered immediately.

    • Further doses (if available) should be administered in alternate nostrils and the patient should be monitored whilst awaiting arrival of the emergency services.

    • EMS may administer further doses according to local guidelines.

4. Assess signs of circulation.

5. Perform a Secondary Survey

  • Perform a secondary survey for evidence of poisoning injury or medication.

  • Beware of any contamination on the casualty.

  • In the case of suspected alcohol poisoning, check the casualty’s blood glucose if that is within your skillset - hypoglycaemia ( <4mmol/l) is common with alcohol overdose.

  • Check the casualty’s pupils using PEARL:

Pupils Possible Cause
Dilated – Unreactive ● LSD
● Amphetamine
● Tricyclic antidepressants.
Constricted – Unreactive ● Heroin
● Morphine
● Codeine.

6. Arrange definitive care

  • For the casualty presenting with normal vital signs, arrange transport to hospital.

  • For the casualty presenting with abnormal vital signs, summon EMS if not already done.

Treatment - Multiple Casualties

Because of the risk to others where there are multiple casualties without clear evidence of a mechanism of injury, UK emergency Services employ STEPS 123 PLUS: (2)

Step 1 - One person is incapacitated with no obvious reason:

  • Approach using standard protocols

Step 2 - Two people are incapacitated with no obvious reason:

  • Approach with caution using standard protocols

Step 3 - Three or more people in close proximity are incapacitated with no obvious reason:

CBRN First Responder Flow Chart

Source: National Ambulance Resilience Unit

  • Use caution and follow step ‘Plus’

Plus - Follow the CBRN First Responder Flow Chart to consider what actions can be undertaken to save life using the following principles:

  • Remove people from the immediate area to avoid further exposure to the substance.

  • Remove outer clothing.

  • Remove the substance from skin using a dry absorbent material to either soak it up or brush it off. Use wet decontamination when a caustic agent is suspected.

  • Communicate, reassure and advise casualties that EMS are on their way.

For the Responder, one’s dynamic Risk Assessment should direct one’s attention to managing scene safety and requesting additional, specialist, support before attempting to assess or treat any casualties.

References

  1. Longo LD, Hill EP. (1977) “Carbon monoxide uptake and elimination in fetal and maternal sheep”. American Journal of Phsiology. 232:324–330.

  2. Home Office (2015) “Initial Operational Response to a CBRN Incident” https://naru.org.uk/wp-content/uploads/2014/05/NARU-IOR-A4-X-3-v8a-2.pdf

  3. https://www.medicines.org.uk/emc/product/9292/smpc#gref Accessed 12th December 2020