Chapter 14 Overdose and self harm
Primary survey positive patient
The objectives of this chapter are listed in Box 14.1. Poisoning and self-inflicted trauma are two of the commonest causes of death and life-threatening emergencies in patients less than 40 years of age. These will present as primary positive patients for the reasons listed in Box 14.2. However be aware that these can be compounded by major trauma as part of the suicide attempt (e.g. falls, hanging and shootings). Recognition and management of these associated injuries are described elsewhere.
Management
The airway
The care of the airway is discussed in Chapter 2. Usually good basic techniques, such as airway opening procedures and patient positioning will be sufficient. Do the least to ensure a clear airway as in some types of drug overdose over aggressive intervention might induce vomiting or extreme bradycardia.
Breathing
Opiate overdose is the commonest cause of drug-induced hypoventilation. The initial management is to open the airway and ventilate using bag/valve mask techniques. Naloxone is a very effective antidote but can wear off before the opiate has been removed from the body. Consequently if the patient wakes up and then refuses to go to hospital, there is a risk that respiratory depression may re-occur once the naloxone is metabolised. As this has led to patients dying JRCALC recommends the titration of the naloxone to keep the patient in a ‘groggy state’. In such circumstances we recommend that naloxone is given slowly to bring the respiratory rate above 10 breaths per minute.
Circulation
Many drugs can cause hypotension; Box 14.3 lists the commonest. The initial management is to obtain IV access, to give fluids and arrange transport to hospital. Simple measures such as raising the legs are also effective. The commonest drugs causing arrhythmia are listed in Box 14.4.
Disability
Fitting due to poisoning indicates severe intoxication but the management remains the same (see Chapter 10). Clear the airway, position the patient, administer oxygen, gain IV access (check the blood glucose) and if needed, give diazepam or lorazepam.
Refusal of treatment by a patient who is threatening suicide is one of the most difficult situations to manage. The reason may be the patient’s lack of capacity to make an informed decision. You will need help. Family, friends or carers are often the most effective in negotiating with the patient and gaining agreement to take the patient to hospital. Alternatively the patient may have regular contact with mental health services or their general practitioner who could be called for advice. The majority of cases will be resolved by negotiation. However there will be some extreme cases where there is an obvious, immediate and real threat to life and when the patient is refusing treatment. If you think the patient lacks capacity to make a reasoned decision then there is a conflict between your responsibility to act in the best interests of the patient and the patient’s rights. There is no ‘right’ answer to such cases as all are different. You must involve other professionals. In extreme circumstances you may have to treat the patient against their wishes, this may require the police. See Chapter 15 for a full discussion on consent, capacity and treatment against the patient’s wishes.
Environment
If the patient has been immobile and unconscious for some time, they may be hypothermic. Pressure sores, aspiration pneumonia and renal failure are other complications. In addition to basic resuscitation care, treat by gradual re-warming, minimal intervention and transport to hospital.
Activated charcoal
This consists of very small particles of charcoal which bind to the drug in the gastrointestinal tract. Its aim is therefore to prevent the toxins absorption into the circulation. It can be used for most poisons but there are some notable exceptions (Box 14.5).
Secondary survey
Subjective information
There are currently few specific tests routinely available in the community that will assist in diagnosing and managing overdoses. History taking and examination are therefore very important (Box 14.6). The identity of any drugs taken, the amount taken and the time of the overdose are the critical parts of the medical history. Check if other drugs or alcohol have been taken. Record any symptoms such as drowsiness, nausea, vomiting. Note the past medical history and current medications. Refer to the British National Formulary or Toxbase for symptoms associated with a specific drug.
Carry out a general screening examination and any specific examination as suggested by patient symptoms or BNF/Toxbase advice. Very often the examination will be normal. Record the vital signs, the mental state assessment and suicide risk (see Chapter 15). The psychological assessment is as important as the physical one. Chapter 15 outlines the assessment of suicide risk and psychiatric examination. The social history is also very important – especially the availability of immediate social support.
Assessment
Each year people with depression account for two-thirds of all deaths from suicide nationally. Risk assessment tools and rating scales can be very helpful, e.g. the Suicide and Self-Harm Risk Assessment Scale, this can most easily be remembered using the SADPERSONS acronym (Box 14.7).
Box 14.7 SADPERSONS risk stratification
 Sex male |
1 |
 Age <19 or >45 |
1 |
 Depression/hopelessness |
2 |
 Previous attempts |
1 |
 Excessive alcohol/drugs |
1 |
 Rational thinking (loss of) |
2 |
 Separated widowed divorced |
1 |
 Organised or serious attempt |
1 |
 No social support |
1 |
 Stated future intent |
2 |
Specific poisons
Aspirin overdose
This commonly available drug can produce a range of symptoms that approximate to its plasma level 4 hours after ingestion (Table 14.1).
| Dose | Effects |
|---|---|
| Mild (300–500 mg/l) | Dizziness and tinnitus Nausea, vomiting Burn mouth sensation |
| Moderate (500–700 mg/l) | As above plus: Hyperventilation Tachycardia, sweaty, vasodilated Gastritis Increased temp Restlessness |
| Severe (> 700 mg/l) | As above plus: Agitation, delirium and coma Heart failure Renal failure Pulmonary oedema |
Beta blockers
Beta blocker overdose causes around 20 deaths a year in the UK, mainly due to respiratory, cardiac and neurological problems (Box 14.8). Be aware it can take many hours to develop all the CVS effect.
Paracetamol
This is the commonest drug to be taken as an overdose. However even a severe paracetamol overdose can have very few symptoms initially and examination is almost always normal (Box 14.9). The history is therefore very important in identifying serious overdoses in the early stages (Box 14.10).
Antidepressant drugs
Selective serotonin reuptake inhibitors (SSRIs)
A variety of effects result from the excess serotonin following an overdose of SSRIs (Box 14.11). This becomes more likely if a combination of SSRIs is taken or they are mixed with serotonergic drugs (lithium, L-tryptophan, pentazocine, clomipramine) or MAOI.
Tricyclic antidepressants
Fortunately since the introduction of SSRIs, less people are taking overdoses of this type of antidepressants. The main problem with the drug is it affects up to five different receptors in the body. These can have a variety of effects, some of which are conflicting (Table 14.2). Consequently treatment of a specific dysrhythmia or neurological effect can lead to a marked over-correction.
Table 14.2 Tricyclic antidepressant drugs – site of action and affect
| Receptor & mechanism | Site | Effect |
|---|---|---|
| Atropine-like (anti-cholinergic) | Muscarinic Central Peripheral | Anxiety, agitation – fitting Hallucinations, delirium Pyrexia Dilated pupils Dry mouth Constipation Tachyarrhythmia Urinary retention Hyperpyrexia Delayed gastric emptying |
| Phenothiazine-like (α-adrenergic blockade) | Central Peripheral | Sedation Vasodilatation Fall in BP |
| Cocaine-like (block uptake of NAdr) | Central α Peripheral α and β | Psychomotor activation Tachyarrhythmia Hypertension |
| Reserpine-like (catecholamine depletion) | Central Peripheral | Sedation, coma Fall in BP Decrease cardiac output Shock |
| Quinidine-like (membrane stabilisation) | Myocardium Conducting pathway | Decrease cardiac output Heart block (any) Increase in QTc, PR, QRS Increase in automaticity & arrhythmias |
All major complications and signs of toxicity will occur within 6 hours of ingestion.
Volatile substance abuse
These are hydrocarbons that are inhaled and are very lipid soluble. Consequently they have a big effect on fat organs, including the brain (Box 14.12). The main problem is that the plasma levels required to get the euphoriant effect lie close to the toxic level. At this point the myocardium is very sensitive to catecholamines and hypoxia. Any shock, frights or exercise can precipitate dysrhythmias, including VF.
Summary
A good knowledge of the issues of consent and assessment of capacity to make informed decisions is important. Judgements in this area can be difficult and seek an immediate further opinion in these circumstances.
Clarke S, Dargan P. Discharge of patients who have taken an overdose of opioids. Emerg Med J. 2002;19:250-251.
Clarke SFJ, Dargan PI, Jones AL. Naloxone in opioid poisoning: walking the tightrope. Emerg Med J. 2005;22:612-616.
Dargan PI, Wallace CI, Jones AL. An evidence based flowchart to guide the management of acute salicylate (aspirin) overdose. Emerg Med J. 2002;19:206-209.
