Medical emergencies

Published on 01/04/2015 by admin

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Chapter 19 Medical emergencies

Medical emergencies occurring in the radiology department may be due to:

1. medication or radiographic contrast given
2. procedure-related complications
3. deterioration of pre-existing morbidities.

Patients may develop cardiac arrhythmias, hypotension, inadequate ventilation or adverse drug/radiographic contrast reactions. Complications arise from sedative drug administration, invasive procedures and human error; poor monitoring and organizational failings may contribute.

If a complication occurs, rapid recognition of the problem and effective management are essential. A call must be made to summon the hospital medical emergency or cardiac arrest team for any medical emergency event that is not immediately reversed or if ongoing care will be required.

The basic principles are summarized in the ABC of resuscitating the acutely ill patient:

A Airway – ensuring a patent airway
B Breathing – providing supplemental oxygen and adequate ventilation
C Circulation – restoration of circulating volume.

These early interventions should proceed in parallel with diagnosis and definitive treatment of the underlying cause. If cardiac arrest is suspected, the adult advanced life support algorithm in Figure 19.1 should be followed.

image

Figure 19.1 Adult Advanced Life Support Algorithm.

Reproduced by kind permission of the Resuscitation Council (UK).

EQUIPMENT

A resuscitation trolley, which is regularly checked, should be kept in the radiology department and contain:

1. a defibrillator
2. a positive pressure breathing device (Ambu bag)and mask
3. supplemental oxygen and oxygen delivery devices
4. suction equipment
5. an intubation tray with airways, laryngoscopes and endotracheal tubes
6. intravenous (i.v.) cannulas and i.v. fluids
7. drugs:

a sedative reversal drugs including naloxone and flumazenil
b resuscitation drugs including adrenaline, atropine and hydrocortisone

8. pulse oximeter
9. non-invasive blood pressure device and appropriately sized cuffs
10. an electrocardiograph.

RESPIRATORY EMERGENCIES

In all cases it is essential to call for urgent anaesthetic assistance if the medical emergency event is not immediately reversed.

RESPIRATORY DEPRESSION

Sedative and analgesic drugs can cause depression of respiratory drive and compromise of the airway leading to hypoxia and hypercapnia. The clinical signs are:

1. decreased, shallow, laboured breathing
2. decreased oxygen saturations
3. in partial airway obstruction, snoring and paradoxical chest wall movement.

The patient should immediately be placed in the supine position. If the airway is compromised it should be maintained by opening the mouth, tilting and extending the head, and lifting the chin. Supplemental oxygen must be provided. If respiratory depression is due to sedative drugs then reversal agents should be considered.

LARYNGOSPASM

This is airway obstruction due to tonic contractions of laryngeal and pharyngeal muscles. Risk factors include excessive secretions and mechanical irritation:

1. In partial obstruction stridor will be present. Partial airway obstruction can be treated with oxygen, coughing and calming measures.
2. In complete obstruction there will be chest wall but no air movement. Immediate anaesthetic assistance is required.

BRONCHOSPASM

This is constriction of bronchial airways by increased smooth muscle tone leading to small-airway obstruction. Risk factors are pre-existing asthma, airway irritation, histamine release and smoking. The signs include:

1. wheeze
2. tachypnoea and dyspnoea
3. decreased oxygen saturations
4. use of accessory respiratory muscles
5. tachycardia
6. silent chest.

Treatment includes high flow oxygen, nebulized salbutamol 2.5–5 mg, nebulized ipratropium bromide 0.25–0.5 mg and i.v. hydrocortisone 100–200 mg.

ASPIRATION OF BLOOD OR GASTRIC CONTENTS INTO THE LUNGS

This occurs when protective reflexes are lost and, if severe, can cause hypoxia, requiring mechanical ventilation. Risk factors are:

1. post-procedure nausea and vomiting
2. obesity
3. hiatus hernia
4. non-adherence to fasting guidelines.

The patient should be placed on their side in the head down position, high-flow oxygen should be administered, airway adjuncts should be removed and the airway suctioned.

PNEUMOTHORAX

This is likely to be related to a procedure such as lung biopsy. Presentation is with unilateral pleuritic chest pain and dyspnoea:

1. For asymptomatic small pneumothorax the patient should be observed.
2. For symptomatic small pneumothorax simple aspiration should be performed and the patient subsequently observed.
3. If the pneumothorax is >2 cm in depth (which is equivalent to 49% of the volume of the hemithorax) an intercostal chest drain should be inserted.
4. If the dyspnoea increases rapidly and the patient becomes cyanosed, tension pneumothorax should be suspected and air should be aspirated immediately by insertion of a 16G cannula through the second intercostal space in the mid-clavicular line.

CARDIOVASCULAR EMERGENCIES

In all cases it is essential to call for urgent anaesthetic assistance if the medical emergency event is not immediately reversed.

HYPOTENSION

This is defined as a fall of greater than 25% from the patient’s pre-procedure systolic blood pressure. Hypotension may be a manifestation of shock, which is a state of circulatory failure resulting in inadequate tissue perfusion to vital organs. The signs of hypotension are pallor, faints, tachycardia, a reduction in capillary refill and oliguria. The common causes are:

1. pharmacological vasodilatation
2. myocardial depression
3. hypovolaemia due to procedure-related haemorrhage or haematoma
4. sepsis
5. vasovagal event.

The treatment depends on cause; pressure should be applied to any developing haematoma, the patient placed in the Trendelenburg position and oxygen administered. In the case of haemorrhage or haematoma, normal blood pressure will not be achievable until bleeding is controlled. For treatment of hypotension, i.v. fluid such as Hartmann’s solution should initially be given as a 500 ml bolus and the patient immediately re-assessed.

TACHYCARDIA

This is classified as a heart rate greater than 100 beats per min and is associated with stimulation of the sympathetic nervous system due to:

1. under-sedation
2. pain
3. hypotension
4. hypoxia.

Heart rates of up to 160 beats per min are generally well tolerated, but tachycardia-induced hypotension or myocardial ischaemia require urgent treatment.

BRADYCARDIA

This is classified as a heart rate less than 60 beats per min and may be due to sedative depressant effect, vasovagal or secondary to hypoxia or pain. Management is as follows:

1. If the patient is non-symptomatic, monitor closely.
2. If hypotension or bradycardia <40 beats per min is present an anticholinergic drug such as atropine 0.3–0.6 mg may be given i.v.
3. If the patient develops asystole or ventricular fibrillation then confirm diagnosis – unconscious, apnoeic, absent carotid pulse. Call for help, defibrillator and cardiac arrest team, and follow the advanced life support algorithm outlined in Figure 19.1.

ADVERSE DRUG REACTIONS

CONTRAST MEDIA REACTION

This is also discussed in detail in Chapter 2. Suggested management is as follows:

1. Nausea/vomiting – patient reassurance. Retain i.v. access and observe
2. Urticaria – retain i.v. access and observe. If troublesome give an antihistamine by slow i.v. injection, e.g. chlorphenamine maleate 10–20 mg. If severe urticaria add i.v. hydrocortisone 100 mg
3. Hypotension with bradycardia (vasovagal reaction)
4. Mild wheeze (see above)
5. Anaphylaxis – rare, most often mild, but may be life threatening. Iodinated i.v. contrast media are the commonest cause of anaphylaxis in the radiology department; however, other possible causes include gadolinium agents, opioid drugs, antibiotics, aspirin, latex and local anaesthetics. Anaphylaxis is a hypersensitivity reaction which causes a range of symptoms and signs including: oedema of face and airway, wheeze, cyanosis, tachycardia, hypotension, erythema and urticaria. Anaphylaxis is likely when all of the following three criteria are met:

a Sudden onset and rapid progression of symptoms
b Life-threatening Airway ± Breathing ± Circulation problems
c Skin or mucosal changes (flushing, urticaria, angio-oedema)

However, it should be noted that skin or mucosal changes alone do not indicate anaphylactic reaction and that these changes are subtle or absent in up to 20% of anaphylactic reactions. The recommended management plan for anaphylaxis is the UK Resuscitation Council algorithm in Figure 19.2

5. Unconscious/unresponsive/pulseless/collapse – see Figure 19.1.
image

Figure 19.2 Anaphylaxis Algorithm.

Reproduced by kind permission of the Resuscitation Council (UK).

LOCAL ANAESTHETIC TOXICITY

Accidental i.v. injection of local anaesthetic or systemic absorption can result in toxicity due to membrane effects on the heart and central nervous system:

1. Early signs of toxicity are tingling around mouth and tongue, light headedness, agitation and tremor.
2. More severe reactions include sudden loss of consciousness, with or without tonic-clonic convulsions and cardiovascular collapse.

The immediate management includes stopping injection, calling for help, maintaining airway (including securing the airway with intubation if required), 100% oxygen, ensuring adequate i.v. access, ventilator and cardiovascular support, and control of seizures. In the event of a cardiac arrest, resuscitation should be prolonged.

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