An unwell young man in the emergency room

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Problem 43 An unwell young man in the emergency room

Jonathan Mitchell, Mohammed M. Rashid

A 33-year-old man presents to the emergency department after informing his partner that he had ingested some tablets 24 hours ago. He is initially alert and fully conscious but obviously upset, complaining of headache and asking for sedation.

Q.1

What questions are particularly important?

Q.2

What investigations would you like to organize first?

The following results become available:

Investigation 43.1 Summary of results

Q.3

How would you interpret these results? What would you like to do next?

He is commenced on IV acetylcysteine and fluids and admitted to the ward. Six hours later, you are called urgently to the ward. The nursing staff are barely able to rouse him and he is groaning and very sweaty.

Q.4

What are you going to do immediately? Describe and justify what you should look for on examination?

Q.5

What are the common causes of coma? What are the likely causes in this patient?

He is unresponsive and sweaty. Pulse 110/min, respiratory rate of 14 breaths and blood pressure 100/60 mmHg. Axillary temperature is 37°C. He is not responding to painful stimulus but his pupil size is normal. He accepts a Guedel airway. A blood glucose is 2.1. You give him 50 mL 50% glucose and start a 10% dextrose infusion. He becomes responsive and fully conscious.

Eight hours later you are called again. He is agitated, confused, aggressive and wants to self-discharge. He has no neck stiffness. He is generally hyper-reflexic. His pupils are equal in size and reactive to light.

Q.6

What is the likely cause for his confusion?

Q.7

What should you do now?

He is taken to the intensive care and intubated. Blood tests now reveal the following:

Investigation 43.2 Summary of results

Q.8

What is happening?

Answers

A.1 All patients with an overdose need a through history including the timing of ingestion, the amount of drugs and if the drugs were taken with alcohol. A collateral history is also important, as is an overdose history. It is useful to classify episodes of attempted self-harm by lethality and by intent, depending on the method used and the patient’s intentions. A paracetamol overdose may be a low intent but often high lethality overdose, as patients may not realize how dangerous large quantities can be.

• All patients should have an immediate blood glucose measurement.

• A 12-lead ECG should be performed. Drugs that cause an abnormal ECG include tricyclic antidepressants and antipsychotics. ECG abnormalities can vary but remember that, a normal ECG on admission should not be overly reassuring especially if suspicion is high. Also, remember that a sinus tachycardia may be the only warning sign of a toxic overdose. If in doubt, monitor!

• Renal and liver function tests are essential. In paracetamol overdose, check the prothrombin time.

• An arterial blood gas may reveal acidosis and hyperlactataemia in many patients, a large proportion of whom are grossly dehydrated at presentation.

• Salicylate and paracetamol levels should be measured in all patients with a suspected overdose.

A.3 He is dry and in renal failure. This urgently needs to be corrected with aggressive fluid resuscitation and monitoring of fluid balance. Following a paracetamol overdose, the patient is often grossly dehydrated which contributes to renal failure and lactic acidosis.

His very high ALT signifies significant hepatic necrosis but is not, in itself, a prognostic marker. Most importantly, he has a prolonged PT signifying early hepatic failure.

He has high levels of paracetamol. N-acetylcysteine should be commenced without any delay, as it is the only intervention that can prevent multi-organ failure in these patients.

• The paracetamol nomogram (Figure 43.1) indicates the risk of hepatic injury associated with a paracetamol concentration at a known time after ingestion and this should be used as guidance for administering acetylcysteine

• In theory, if the paracetamol concentration lies above the treatment line, N-acetylcysteine should be given. N-acetylcysteine should ideally be started within 8 hours of ingestion.

• In practice, the timing of drug overdose is notoriously unreliable. If the patient has taken a substantial amount of paracetamol (>7.5 g in an adult) or if there is any doubt whatsoever, or if the patient has abnormal liver enzymes despite a paracetamol level below the treatment line then treatment should be started immediately. Always seek expert advice.

Figure 43.1 Paracetamol treatment chart.

(Courtesy of the Clinical Services Unit of the Royal Adelaide Hospital.)

All patients with deliberate self-poisoning should be assessed by psychiatric services.

A.4 This is a medical emergency.

A: Check and safeguard his airway

B: Check for spontaneous breathing, apply high-flow oxygen and measure his respiratory rate. Roll the patient on to his side (the ‘coma position’). Markedly abnormal breathing patterns are seen in brainstem damage. Compensatory hyperventilation is seen early in metabolic acidosis (e.g. diabetic ketoacidosis, salicylate, methanol, ethylene glycol and other poisonings). Hypoventilation is common in all cases of generalized CNS depression.

C: Measure blood pressure, pulse and assess him for signs of shock. Insert a large bore intravenous cannula, noting his response to painful stimuli. Take blood for laboratory analysis. Commence intravenous isotonic saline. Monitor cardiac rhythm.

Measure blood glucose immediately. He has taken a paracetamol overdose and may have become hypoglycaemic secondary to acute liver failure.

Hypoglycaemia is easily treated, easily missed, and can be fatal. If there is delay or any doubt, administer 50 mL 50% glucose intravenously. This will not do any harm and, if the patient is hypoglycaemic, may save their life.

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