Overdose and poisoning is an almost daily occurrence for many Paramedics, drugs of abuse come in many forms which include:
- · Illegal drugs such as cannabis, cocaine and narcotics
- · Alcohol
- · Prescription drugs
- · Drugs bought over the counter
- · Harmful chemicals found around the house
- · Poisons from dangerous reptiles
- · Poisons commonly found in the country and mistaken for food
According to Caroline (2007) toxicology emergencies fall into two categories, intentional and unintentional. In adult age groups it is more likely to be intentional. She carries on to say that whilst there are many drugs that are dangerous, they often produce similar effects. The syndrome like symptoms that of a poison is called a Toxidrome. The major toxidromes are produced by, stimulants, narcotics, cholinergics, anticholinergics, sympathomimetics and sedative hypnotics.
|
Toxidrome |
Drug Example |
Signs & Symptoms |
|
Stimulant |
Cocaine, Amphetamine |
Restless Insomnia Tachycardia hyper-hypotension, Paranoia Convulsions Cardiac Arrest |
|
Narcotic, Opiate, Opioid |
Heroin, Morphine Tramadol |
Hypotension decreased LOC Agitation Resp Depression Pin Point Pupils |
|
Sympatthomimetic |
Methamphetamine Amphetamine |
Agitation Tachycardia Fits Hyperthermia |
|
Sedative and Hypnotic |
Diazepam Temazepam Zopiclone Phenobarbital |
Decreased LOC Ataxia Slurred speech Hypotension |
|
Cholinergic |
Sarin Tabun |
Dry flushed skin Increased salivation GI Upset Resp Depression |
|
Anticholinergics |
Atropine Buscopan Anti Histamines Anti Psychotics |
Dry flushed skin Dilated Pupils Tachycardia Blurred vision |
Within the authors scope of practice the most common toxidromes encountered are: Alcohol, Sedative Hypnotics and Narcotic based drugs.
Acute alcohol poisoning and acute alcohol withdrawal are medical emergencies. Severe alcohol ingestion will cause CNS depression and potentially death caused by airway occlusion respiratory depression and aspiration.
According to Toxbase (2011) the National Poisons Information Service Alcohol and pure Ethanol is rapidly absorbed from the GI tract. Adults absorb 80-90% of ingested alcohol within 1 hour and on average metabolise it at a rate of 100-125 mg/kg per hour (reducing blood concentrations by approximately 150-200 mg/L (3.26-4.35 mmol/L) per hour. Tolerant drinkers metabolise ethanol at higher rates and therefore blood concentrations fall more rapidly. Volume of distribution for ethanol is 0.4 - 0.6 L/kg
Alcohol is more dangerous when mixed with other drugs especially those which cause CNS depression.
Toxbase and Caroline (2007) suggest that all patients with severe alcohol poisoning should be taken to hospital. Assessment should follow the ABCDE approach and co ingestion of other drugs should be considered.
Toxbase (2011) suggest the following treatment:
|
1. |
Ensure a clear airway and adequate ventilation, particularly in obtunded patients. Ventilation may be required for respiratory depression. |
|
2. |
Gut decontamination is unlikely to be of benefit since ethanol is rapidly absorbed and activated charcoal does not significantly reduce the rate of absorption. |
|
3. |
Observe for at least 4 hours if > 0.4 mL/kg body weight of absolute ethanol had been ingested in a child (< 10 years) (i.e. 1 mL/kg 40% spirit, 4 mL/kg 10% wine or 8 mL/kg 5% beer). Observe adults with features of moderate or severe toxicity for a minimum of 6 hours. |
|
4. |
Monitor pulse, blood pressure, cardiac rhythm, conscious level, respiratory rate and body temperature. |
|
5. |
Monitor blood glucose in all patients. |
|
6. |
Measure urea, electrolytes, creatinine kinase, LFTs, arterial blood gases and blood ethanol concentration in patients with features of moderate to severe toxicity and perform 12 lead ECG. |
|
7. |
Correct hypoglycaemia as quickly as possible. If the patient is awake give oral glucose followed by a carbohydrate meal. Adults: If the patient is drowsy or unconscious give up to 250 mL 10% or 125 mL 20% glucose IV rapidly (titrated to patient responsiveness). Continue an appropriate infusion to maintain consciousness and/or normal blood glucose. If hypoglycaemia persists 50 mL 50% glucose IV may be given but is irritant to veins and can cause skin necrosis in cases of extravasation.
Children: Initially 5 mL/kg of 10% glucose IV repeated as necessary. Higher concentrations of glucose may be required for severe hypoglycaemia. Glucagon is rarely effective. |
|
8. |
Consider treating chronic alcohol abusers with intravenous thiamine (e.g. Pabrinex 10 mL over 30 mins) to protect against the onset of Wernicke’s encephalopathy. Intravenous thiamine MUST be administered before giving dextrose to chronic alcohol abusers. |
|
9. |
Correct hypotension by raising the foot of the bed and by giving an appropriate fluid challenge. Treat brady and tachyarrhythmias appropriately. Children failing to respond to an appropriate intravenous fluid bolus require early discussion with the local paediatric intensive care unit (PICU). Adults: If severe hypotension persists despite the above measures, then central venous pressure monitoring should be considered. Manage in a critical care area or involve the critical care outreach team. When hypotension is mainly due to decreased systemic vascular resistance, drugs with alpha-adrenergic activity such as noradrenaline or high dose dopamine (10-30 micrograms/kg/min) may be beneficial. The dose of vasopressor should be titrated against blood pressure. When hypotension is believed to be due to reduced cardiac output (e.g. where global hypokinesia is demonstrated on echocardiography) inotropic drugs such as dobutamine, or in severe cases adrenaline, may be beneficial. NOTE: Both negative inotropic and vasodilator actions may both be present, particularly in mixed overdoses. |
|
If severe hypotension further persists discuss with your local poisons information service: in the UK NPIS 0844 892 0111, in Ireland NPIC (01) 809 2566. |
Sedative Hypnotics
Form a wide variety of drugs used to sedate patients reduce, anxiety and aid sleep. According to Caroline (2007) they are all a CNS depressant and the most commonly found group of drugs are the Benzodiazepine i.e. Diazepam and their derivatives such as the Zopiclone, Zolpidem.
Benzodiazepines act by stimulating the gamma amminobutyric acid pathway, resulting in sedation, reduced anxiety and relaxation of smooth muscle.
Patients will often exhibit altered levels of consciousness, confusion, slurred speech and ataxia.
ABCD Approach to assessment should be followed. Co ingestion of alcohol is common and close observation is required. Toxbase (2011) recommend the following for the treatment of Diazepam, but specific advice is available for all the Benzodiazepines:
|
1. |
Maintain a clear airway and adequate ventilation if indicated. |
|
2. |
The benefit of gastric decontamination is uncertain. Consider activated charcoal (charcoal dose: 50 g for an adult, 1 g/kg for a child) in adults or children who have taken more than a potentially toxic amount within 1 hour, provided the airway can be protected. |
|
3. |
Patients who are asymptomatic at 4 hours are unlikely to develop severe toxicity. |
|
4. |
Monitor level of consciousness, respiratory rate, pulse oximetry and blood pressure in symptomatic patients. |
|
5. |
Consider arterial blood gas analysis in patients who have a reduced level of consciousness (GCS < 8; AVPU scale P or U) or have reduced oxygen saturations on pulse oximetry. |
|
6. |
Correct hypotension by raising the foot of the bed and by giving an appropriate fluid challenge. Treat brady and tachyarrhythmias appropriately. Children failing to respond to an appropriate intravenous fluid bolus require early discussion with the local paediatric intensive care unit (PICU). Adults: If severe hypotension persists despite the above measures, then central venous pressure monitoring should be considered. Manage in a critical care area or involve the critical care outreach team. When hypotension is mainly due to decreased systemic vascular resistance, drugs with alpha-adrenergic activity such as noradrenaline or high dose dopamine (10-30 micrograms/kg/min) may be beneficial. The dose of vasopressor should be titrated against blood pressure. When hypotension is believed to be due to reduced cardiac output (e.g. where global hypokinesia is demonstrated on echocardiography) inotropic drugs such as dobutamine, or in severe cases adrenaline, may be beneficial. NOTE: Both negative inotropic and vasodilator actions may both be present, particularly in mixed overdoses. |
|
|
|
|
7. |
Supportive measures as indicated by the patient's clinical state. |
|
8. |
Flumazenil (Anexate), a benzodiazepine antagonist, is available but should rarely be required. It may be required in children who are naive to benzodiazepines or patients with COPD as an alternative to ventilation. Flumazenil has a short half-life (about an hour) and in this situation an infusion may therefore be required. Flumazenil should not normally be used in patients with a history of seizures, head injury, chronic benzodiazepine use, co-ingestion of a benzodiazepine and tricyclic antidepressant or other proconvulsant - Instructions for its use follow. |
Narcotic Drugs
Narcotics, opiates and Opioids are used to treat pain. Opiate is a naturally occurring substance and Opioids synthetically manufactured drugs. According to Toxbase narcotics remain the most common cause of overdose and death reported to the service.
Narcotic Agents include:
- · Morphine
- · Heroin
- · Codeine
- · Oxycodone
- · Tramadol
Classic presentation of narcotic overdose include; euphoria, pin point pupils, hypotension, respiratory depression, nausea and vomiting.
ABCD approach to care should be adopted because of the high risk of respiratory depression advanced life support measures may well be needed and hospital assessment will be required (Caroline 2007).
Toxbase (2011) Suggest the following management plan for an unconscious heroin overdose:
1. Give naloxone preferably intravenously (0.4 to 2 mg for an adult and 0.01 mg/kg body weight for children) if coma or respiratory depression is present. Repeat the dose if there is no response within two minutes. Naloxone is a competitive antagonist and large doses (4 mg) may be required in a seriously poisoned patient.
Intramuscular naloxone is an alternative in the event that IV access is not possible, or if the patient is threatening to self-discharge when it may help reduce the risk of respiratory arrest.
Nebulised naloxone has been successfully used in one case of methadone poisoning (Mycyk, 2003).
Failure of a definite opioid overdose to respond to large doses of naloxone suggests that another CNS depressant drug or brain damage is present.
2. Observe the patient carefully for recurrence of CNS and respiratory depression. The plasma half-life of naloxone is shorter than that of all opioid analgesics - REPEATED DOSES OF NALOXONE MAY BE REQUIRED.
Intravenous infusions of naloxone may be useful where repeated doses are required. An infusion of 60% of the initial dose per hour is a useful starting point. A solution containing 10 mg (25 vials) made up in 50 mL dextrose will produce a 200 micrograms/mL solution for infusion using an IV pump (dose adjusted to clinical response). Infusions are not a substitute for frequent review of the patient's clinical state.
3. All patients should be observed for at least 6 hours after the last dose of naloxone. Monitor BP, pulse, respiratory rate, oxygen saturation and conscious level at least every 15 minutes initially.
4. Do not delay establishing a clear airway, adequate ventilation and oxygenation if there is no response to naloxone.
5. Assisted ventilation with positive end-expiratory pressure may be necessary if pulmonary oedema is a complication.
6. Consider activated charcoal if a sustained release preparation has been ingested.
7. Other supportive measures as indicated by the patient's progress.
References
Caroline, N. (2007) Emergency Care in the Streets (6th Edn) Jones and Bartlett, London.
http://www.toxbase.org (Accessed on the 23rd April 2011)
Written by Patrick Vennard
NHS Ambulance Specialist Practitioner.
- West Midlands Ambulance Service, Hereford Division





Excellent, well written article. Thank you Patrick