Emergency medicine

Methods

Many advances have been made in emergency medicine recently. I surveyed colleagues both locally and internationally to nominate suitable topics. The topics I have chosen were considered to be clinically useful and educational. They reflect subjects of change or advancement. Once the topics were chosen, I performed a directed review of leading relevant journals, mostly from publications in 2000-1. Because of space restrictions, this article cannot be a comprehensive review of all recent advances.

Overcrowding in the emergency department

Overcrowding in the emergency department is the biggest impediment to the delivery of timely and adequate emergency care. It is an international problem, and it is getting worse.2 It is often manifest as diversion of ambulances—an emergency department instructs the ambulance service to divert ambulances elsewhere because it is unsafe for more patients to attend.

Overcrowding in the emergency department is caused by a complex web of inter-related issues; these have been reported previously and are summarised in box 1 and box 2 2 Figure 1 outlines basic processes of patient flow in the emergency department. In simple terms, if inflow is greater than outflow the result is overcrowding. This has been called “exit block” in the past, but it is now referred to as “access block,” as the patient is denied access to ongoing inpatient care.

Fig 1

Flow of patients in an emergency department

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The main cause of access block is a lack of beds for acute inpatients. Some emergency departments are, however, experiencing “entry block” or entry overload—overwhelming numbers of patients presenting to the emergency department in a short time (fig 2). This results in impaired access to emergency care.3

Fig 2

A typical scene of overcrowding in an emergency department. Situations such as these lead to loss of clinical productivity and effectiveness and place the safety of patients at risk

(Credit: ED LETTAU/PETER ARNOLD INC/SPL)

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Health systems in the United States, United Kingdom, Australia and New Zealand, and Canada are having similar difficulties, which implies that a profound change has occurred in the delivery of Western medicine. Health care in Western societies has been through a period of severe economic rationalisation, resulting in the closure of thousands of beds in the acute hospital system. In the United States, the number of medical and surgical beds declined by 18% in 1994-9. From 1990 to 1999, attendances at emergency departments increased by 15%.4 Many beds for elderly people have been closed or changed to community based facilities.

After a decade of hospitals downsizing and reducing operating costs, local healthcare systems have been left with little slack to accommodate unforeseen trends in the number of patients.4 Stopgap measures (box 3) provide only some temporary relief.

Longer term measures are required to deal with all the causes of overcrowding in emergency departments. Governments at all levels need to recognise and acknowledge the problem, which requires a system-wide approach. The government of the Australian state of Victoria has published a paper on how to manage emergency demand, which reports that the equivalent of another major suburban hospital is required.5 Opening additional beds in 1999-2000 led to a reduction of 24% in the number of patients waiting in emergency departments for admission for longer than 12 hours, and the episodes of ambulance diversion fell by 30%. In July, August, and September 2000, however, access block and ambulance diversions increased again, showing that the hospital system was operating at capacity and was unable to absorb further pressure.5

Emergency departments are the main point of entry into inpatient settings for people requiring non-elective acute hospital care. If all else fails in the health system, the emergency department is always available to help. That basic tenet is now being challenged, and the general public may no longer be able to rely on emergency departments for emergency care that is timely and of high quality.2

Resuscitation in cardiac arrest

As a result of an international conference in 2000, revised guidelines and algorithms on cardiopulmonary resuscitation and emergency cardiovascular care have been published (fig 3). Drugs such as adrenaline, antiarrhythmics, and buffer agents have been relegated to a secondary role. Systematic reviews show that no evidence exists to confirm a benefit resulting from these agents.6

Fig 3

International algorithm for advanced cardiac life support (adapted from Resuscitation Council UK website, www.resus.org.uk/pages/alsalgo.pdf). (BLS=basic life support, VF/VT=ventricular fibrillation/ventricular tachycardia, CPR=cardiopulmonary resuscitation, ACS=acute coronary syndrome)

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Two new drugs have been recommended, vasopressin and amiodarone. Vasopressin is included as an option in the algorithm for ventricular fibrillation and ventricular tachycardia (level of evidence: acceptable, not harmful, supported by fair evidence).6 Vasopressin, a natural antidiuretic hormone, becomes a powerful vasoconstrictor when used at much higher doses than are normally present in the body. The drug has positive effects that duplicate the positive effects of adrenaline, but it does not replicate the adverse effects of adrenaline.6

Vasopressin is recommended as a single dose of 40 units. Its half life is 10-20 minutes, compared with the 3-5 minute half life of adrenaline. It can be given as an alternative to adrenaline, but a recent trial indicates the outcome is the same as with adrenaline.7 Adrenaline at high dosage (0.1 mg/kg) is not recommended for routine use but can be considered if doses of 1 mg fail.6

Amiodarone has a similar level of evidence as vasopressin and is supported by a better evidence base than any other antiarrhythmic drug.6 It should be the first choice antiarrhythmic drug for ventricular fibrillation and ventricular tachycardia that do not respond to defibrillation. The recommended dose for patients with cardiac arrest is 300 mg given intravenously as a bolus. If ventricular fibrillation or pulseless ventricular tachycardia recurs, a second dose of 150 mg should be considered. Lignocaine has an indeterminate level of recommendation.6

Biphasic defibrillators are now commonplace. They deliver current that flows in a positive direction for a specified duration. The current then reverses and flows in a negative direction for the remaining milliseconds of the electrical discharge. Biphasic waveforms have proved superior to monophasic waveforms for defibrillation by implantable defibrillators.6 Further research indicates that repetitive biphasic waveform shocks at lower energy (repeated shocks at <200 J) have equivalent or higher success for eventual termination of ventricular fibrillation than defibrillators that increase the current with successive escalating shocks (200 J, 300 J, 360 J). The energy level of the biphasic first shock yielding the highest termination rate of fibrillation is unknown.6

A more recent development in resuscitation of patients with cardiac arrest is the role of thrombolysis. Initial results show that thrombolysis in cardiac arrest may represent an important advance. 8 9

Toxicology update

Up to 5% of patients presenting to an emergency department have taken an overdose. The drugs taken most often include benzodiazepines, paracetamol, alcohol, antidepressants, antipsychotics, anticonvulsants, and non-therapeutic substances. Many ingestions involve multiple drugs.

As new drugs are developed and released, inevitably patients take overdoses of them. This section briefly reviews some of these drugs that are now seen in overdose, or some of the newer treatment options. One such drug is bupropion, which has been licensed to help people stop smoking. Large quantities of bupropion have been prescribed over a short time. Buproprion is a unique monocyclic antidepressant that has structural similarities to amphetamines. Seizures have been a major concern with therapeutic use of bupropion, at a rate of around 0.4%. One study found a seizure rate of 21% in patients who had taken an overdose. Most convulsions either stopped spontaneously or were controlled with benzodiazepine. The time to onset of the first seizure ranged from 1 hour to 8 hours (mean 3.7 hours). Other toxicity affecting the central nervous system included lethargy, tremors, confusion, lightheadedness, hallucinations, and paresthesias. Sinus tachycardia is the most common cardiovascular effect. 10 11 Treatment is supportive.

Another recent development is the use of atypical antipsychotic agents (respiridone, clozapine, quetiapine, olanzapine, ziprasidone, sertindole), which have largely replaced traditional agents as first line drugs for the treatment of schizophrenia. Most patients who take an overdose of atypical antipsychotic drugs will remain asymptomatic or develop only mild to moderate toxicity. Death is rare. Toxic effects begin within 1-2 hours after ingestion and peak by 4-6 hours. Toxicity is variably characterised by depression of the central nervous and respiratory systems, meiosis or mydriasis, hypertension or orthostatic hypotension, sinus tachycardia, agitation, delirium, anticholinergic stigmata, and, uncommonly, seizures and arrhythmias. Treatment is primarily supportive.12

A new treatment has been reported for poisoning with calcium channel blockers.13 Conventional treatment includes intravenous fluids, calcium, dopamine, dobutamine, noradrenaline, and glucagon. Inducing hyperinsulinaemia and euglycaemia as adjunctive treatment has resulted in striking benefits (dosage 0.5 units insulin/kg body weight/h, 10% dextrose 100 ml/h). The exact mechanism is poorly defined.

Overdose of sulphonyl urea is potentially life threatening. Traditional treatment includes intravenous dextrose and frequent monitoring of blood glucose concentrations. A dose of dextrose is a potent stimulus for additional release of insulin and often results in rebound hypoglycaemia that can be recurrent and prolonged. Octreotide acetate, a synthetic octapeptide analogue of the endogenous human hormone somatostatin, directly inhibits the secretion of insulin from the pancreas and prevents rebound hypoglycaemia. In one review, the dosing of octreotide ranged from a single subcutaneous dose of 40 μg to an intravenous infusion of 125 μg/hour.14

For people who take overdoses to harm themselves deliberately emergency departments need to address the psychiatric aspects of attempted suicide. Recent guidelines for the management of deliberate self harm in young people represent a consensus overview on the reasonable management of deliberate self harm in young people.15

Finally, with the new risks of bioterrorism, emergency physicians need to lead in the early diagnosis of illnesses such as anthrax, smallpox, plague, tularaemia, and botulism. Clinical vigilance for unusual or unexplained clusters of illness is the key to early detection and reporting.16

Improved clinical criteria for imaging