Further management
Following cessation of the fit, all children will need continuous monitoring for vital functions and to observe for further convulsions. It is particularly important to ensure that breathing is adequate since the benzodiazepines used to control the fit may cause respiratory depression.
After the fit has been controlled the clinician must consider the underlying cause of the convulsion. In many cases there will be an infectious cause, either a benign, self-limiting infection causing ‘febrile status’ or possibly meningitis. See Chapter 12.
paediatric cardiologist because of the dangers of too rapid reduction.
Monitoring of visual acuity and pupils is crucial during this time as lowering the blood pressure may lead to infarction of the optic nerve heads. Any deterioration must be treated by urgently raising the blood pressure using intravenous saline or colloid.
Some children may be anuric – renal function (serum creatinine, urea, and electrolytes) should be analysed promptly.
Some drugs commonly used to achieve blood pressure reduction in children are shown in Table 13.1.
Table 13.1. Drug therapy of severe hypertension
Some specialists may recommend the use of nifedipine as a temporary measure before transfer; if any drug is used, the child should have the blood pressure monitored as above and an intravenous infusion in place.
These children should be cared for in a unit experienced in paediatric hypertension.
This will usually be the regional paediatric nephrology (or paediatric cardiology) centre.
It is essential that adequate consultation takes place before transfer.
THE CONVULSING CHILD
Drug Dose Comments
Labetalol 16–50 µg/kg/min - and ß-blocker. Titratable infusion. DO NOT USE in patients with fluid overload Sodium nitroprusside 0·2–1 µg/kg/min Vasodilator.
Very easy to adjust dose.
Protect from light. Monitor cyanide levels Hydralazine 0·2–1 µg/kg/min Vasodilator. Titratable infusion.
Adjust as required
Nifedipine 0·25 mg/kg Vasodilator. Fluid can be drawn up from capsules and squirted into mouth sublingually.
Better to bite the capsule and swallow.
May be difficult to control BP drop because it is given as a bolus
CHAP TITLE
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CHAPTER
I 14 I
The poisoned child
INTRODUCTION
Suspected poisoning in children results in about 40,000 attendences at Emergency departments each year in England and Wales. Around half of these children are admitted to hospital for treatment or observation. Precise data on hospital admissions for poisonings are altered by the fact that many Emergency departments and paediatric wards have special areas where children who have taken a substance of low toxicity can be observed for a few hours without being formally admitted.
Deaths from ingested poisons are uncommon, and are due to drugs (especially tricyclic antidepressants), household products and, rarely, plants. As can be seen from Table 14.1, more children die each year from inhalation of carbon monoxide and other gases in household fires, than die from accidental poisoning by drugs although fire deaths are decreasing while poisoning deaths are not.
Table 14.1. Deaths in children (ages 1–14) from poisons in England and Wales
Office of National Statistics 1998
There has been a steady decline in the number of childhood deaths from poisonings.
The selective introduction of child-resistant containers (CRCs) in 1976, together with other measures, has reduced the number of poisonings and hospital attendances. In the case of salicylate poisoning the introduction of CRCs saw an 85% fall in hospital admissions from 1975 to 1978. It should be remembered, however, that 20% of children under the age of five years are capable of opening CRCs!
CHAP TITLE
Cause of death 1988 1998
From poisoning by drugs, 16 18
medicaments and biological substances
From toxic effects of carbon monoxide 36 15
From toxic effect of other gases, fumes or vapours 56 24
Accidental poisoning
This is usually a problem of the young child or toddler, with a mean age of presentation of two and a half years. Accidental poisoning usually occurs when the child is unsupervised, and there is an increased incidence in poisoning following recent disruption in households, such as a new baby, moving house or where there is maternal depression.
Intentional overdose
Suicide or parasuicide attempts are usually made by young people in their teens although sometimes they may be as young as eight or nine years. These children or adolescents should undergo psychiatric and social assessment.
Drug abuse
Alcohol and solvent abuse are the commonest forms of drug abuse in children in the UK.
Iatrogenic
The commonest offender is diphenoxylate with atropine (Lomotil). This combination is toxic to some children at therapeutic doses. The most frequently fatal drug is digoxin.
Deliberate poisoning
Rarely, symptoms are induced in children by adults via the administration of drugs.
A history of poisoning will often not be given at presentation.
Most poisoning episodes in childhood and adolescence are of low lethality and little or no treatment is required. This chapter will not address the milder cases but will enable the student to develop an approach to the seriously ill poisoned child with additional advice on the management of specific poisons.
PRIMARY ASSESSMENT
Airway
Assess airway patency by the “look, listen, and feel” method.
If the child can speak or cry in response to a stimulus, this indicates that the airway is patent, that breathing is occurring and that there is adequate circulation. If the child responds only with withdrawal to a painful stimulus (AVPU score “P”) his airway is at risk.
If there is no evidence of air movement then chin lift or jaw thrust manoeuvres should be carried out and the airway reassessed. If there continues to be no evidence of air movement then airway patency can be assessed by performing an opening manoeuvre and giving rescue breaths (see Basic Life Support, Chapter 4).
Breathing
Assess the adequacy of breathing.
THE POISONED CHILD
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Monitor oxygen saturation with a pulse oximeter.
Circulation
Assess the adequacy of circulation
Monitor heart rate/rhythm, blood pressure and core/toe temperature difference.
If heart rate is above 200 in an infant or above 150 in a child or if the rhythm is abnormal perform a standard ECG. QRS prolongation and ventricular tachycardia is seen in tricyclic antidepressant poisoning.
Disability
Assess neurological function:
• A rapid measure of level of consciousness should be recorded using the AVPU scale.
• Depression of conscious level suggests poisoning with opiates, sedatives (such as benzodiazapines) antihistamines, hypoglycaemic agents.
• Pupillary size and reaction should be noted Very small pupils suggest opiate or organophosphate poisoning, large pupils amphetamines, atropine, tricyclic antidepressants.
• Note the child’s posture. Hypertonia is seen in amphetamine, ecstasy, theophylline and tricyclic antidepressant poisoning.
• The presence of convulsive movements should be sought. Convulsions are associated with any drug that causes hypoglycaemia (ethanol) and with tricyclic antidepressant poisoning.
Exposure
Take the child’s core and toe temperatures. A fever suggests poisoning with ecstasy, cocaine or salicylates. Hypothermia suggests poisoning with barbiturates or ethanol.
THE POISONED CHILD
• Effort of breathing Recession
Respiratory rate. The rate may be increased in poisoning from amphetamines, ecstasy, salicylates, ethylene glycol, methanol.
• Efficacy of breathing Breath sounds
Chest expansion/abdominal excursion
• Cardiovascular status
Heart rate. Tachycardia is caused by amphetamines, ecstasy, ß-agonists, phenothiazines, theophylline and tricyclic antidepressants. Bradycardia is caused by beta-blockers, digoxin, organophosphates.
Pulse volume Capillary refill
Blood pressure. Hypotension is commonly seen in serious poisoning hypertension is caused by ecstasy and monoamine oxidase inhibitors
• Effects of circulatory inadequacy on other organs
Acidotic sighing respirations. This may suggest metabolic acidosis from salicylate or ethylene glycol poisoning as a cause for the coma.
Pale, cyanosed or cold skin
RESUSCITATION
Airway
• A patent airway is the first requisite. If the airway is not patent it should be opened and maintained with an airway manoeuvre and the child ventilated by bag-valve-mask oxygenation. An airway adjunct can be used. The airway should then be secured by intubation by experienced senior help.
• If the child has an AVPU score of “P”, his airway is at risk. It should be maintained by an airway manoeuvre or adjunct and senior help requested to secure it.
Breathing
• All children with respiratory abnormalities, shock or a decreased conscious level should receive high flow oxygen through a face mask with a reservoir as soon as the airway has been demonstrated to be adequate.
• A number of agents taken in overdose (particularly narcotics) can produce respiratory depression. Oxygen should be given, but it is important to remember that these patients may have an increasing carbon dioxide level despite a normal oxygen saturation whilst breathing oxygen. Inadequate breathing should be supported using a bag-valve-mask device with oxygen or by intermittent positive pressure ventilation in the intubated patient.
Circulation
• A number of poisons can produce shock, by a number of different mechanisms.
Hypovolaemia may be caused by gastrointestinal bleeding from iron poisoning or there may be vasodilatation from barbiturates. Shock should be treated with a fluid bolus, as usual. If possible, inotropes should be avoided in poisoning cases as the combination of toxic substance producing shock and an inotrope may be pro-arrhythmogenic.
• Cardiac dysrhythmias can be expected in tricyclic antidepressant (TCA), digoxin, quinine and anti-arrhythmic drug poisoning. Some anti-arrhythmic treatments are contraindicated with certain poisons. See below for advice on TCA poisoning and contact a Poison Centre urgently for other advice.
Gain intravenous or intraosseous access
• Take blood for FBC, U&Es, toxicology, paracetamol and salicylate levels (in patients who have taken an unknown drug) glucose stick test and laboratory test.
Give 5 ml/kg of 10% dextrose to any hypoglycaemic patient.
• Give 20 ml/kg rapid bolus of crystalloid to any patient with signs of shock.
• If a child has a tachyarrhythmia and is shocked, up to three synchronous electrical shocks at 0·5, 0·5 and 1 joule should be given. If the arrhythmia is broad complex and the synchronous shocks are not activated by the defibrillator then attempt an asynchronous shock. A conscious child should be anaesthetised first if this can be done in a timely manner. DC shock may be dangerous in digoxin poisoning. Use lignocaine, amiodarone or phenytoin.
Disability
• Treat convulsions with diazepam or lorazepam.
• Give a trial of naloxone established in cases where depressed conscious level and small pupils suggest opiate poisoning.
THE POISONED CHILD
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In all cases of serious poisoning early consultation with a Poisons Centre is mandatory.
Such centres have a wealth of expertise in the management of poisoning and will advise on the individual patients needs.
Monitoring
• ECG.
• Blood pressure (use appropriate size cuff).
• Pulse oximetry.
• Core temperature.
• Blood glucose.
• Urea and electrolytes.
• Blood gases (where indicated).
Lethality assessment
At the end of the primary assessment, it is important to assess the potential lethality of the overdose. This requires knowledge of the substance that has been taken, the time it was taken and the dosage. This information may be unattainable in the unwitnessed poisoning episode of a toddler or that of an unconscious or uncooperative adolescent.
Some clues about the drug ingested may be available from physical signs noted during the primary assessment (Table 14.2).
Table 14.2. Diagnostic clues from the primary assessment
Some investigation results can add clues to the diagnosis of an unknown poison.
THE POISONED CHILD
Signs Drug
Tachypnoea Aspirin, theophylline, carbon monoxide, cyanide
Bradypnoea Ethanol, opiates, barbiturates, sedatives
Metabolic acidosis (sighing respirations) Ethanol, carbon monoxide, ethylene glycol
Tachycardia Antidepressants, sympathomimetics,
amphetamines, cocaine
Bradycardia ß-blockers, digoxin, clonidine
Hypotension Barbiturates, benzodiazepines, ß-blockers,
calcium channel blockers, opiates, iron, phenothiazines, phenytoin, tricyclic antidepressants
Hypertension Amphetamines, cocaine, sympathomimetic agents
Small pupils Opiates, organophosphate insecticides,
phenothiazines
Large pupils Amphetamines, atropine, cannabis,
carbamazepine, cocaine, quinine, tricyclic antidepressants
Convulsions Carbamazepine, lindane organophosphate
insecticides, phenothiazines, tricyclic antidepressants
Hypothermia Barbiturates, ethanol, phenothiazines
Hyperthermia Amphetamines, cocaine, ecstasy,
phenothiazines, salicylates
1. Metabolic acidosis can be found in poisoning from:
• Carbon monoxide
• Ecstasy
• Ethylene glycol
• Iron
• Methanol
• Salicylates
• Tricyclic antidepressants.
2. Enlarged anion gap (Na + K)-(HCO3– Cl)>18 can be found in poisoning from:
• Ethanol
• Ethylene glycol
• Iron
• Methanol
• Salicylates
3. Hypokalaemia can be found in poisoning from:
• ß-agonists
• Theophylline
4. Hyperkalaemia can be found in poisoning from:
• Digoxin
The risks of a particular overdose can be assessed once all the information has been gathered. Complex or life-threatening cases should be discussed with a Poisons Centre.
The Poisons Centre will require the following information:
• Age and weight of the patient.
• The time since exposure.
• The substance.
• The amount taken together with any description or labelling.
• The patient’s condition.
If the nature of the overdose is unknown then a high potential lethality should be assumed.
Many childhood poisoning incidents have zero lethality and no treatment is required.