Anaesthetic Emergencies - Answers

Arlo Guthrie — Tue, 21 Apr 2009 11:41:35 GMT

Current Revision posted to Revision Guide For Student Nurses - Part 2 by Arlo Guthrie on 4/21/2009 11:41:35 AM

ANSWERS

Treatment of an anaesthetic emergency must be prompt. List 3 important factors that will enable a crisis to be dealt with efficiently.
- The provision of a suitably stocked emergency kit.
- The provision of training in resuscitation procedures.
- The provision of a ready source of information with regard to emergencies.
List 6 properties of the emergency kit.
- Portable with easy access.
- Kept clean and tidy.
- Contains only essential items.
- Includes clear, concise instructions on resuscitation procedures.
- Dosage instructions clearly visible.
- Contains a list of contents to ensure that contents are replenished following use.
List drugs commonly found in the emergency kit.
- Sodium chloride 0.9% for intravenous infusion - for the correction of shock, dehydration and electrolyte imbalance.
- Potassium chloride - for hypokalaemia.
- Adrenaline injection - for cardiac arrest.
- Calcium borogluconate - for hypocalcaemia.
- Sodium bicarbonate - for electrolyte imbalance.
- Atropine sulphate - for bronchodilation and reduction of airway resistance, control of intra-operative vagally mediated bradycardia.
- Lignocaine hydrochloride - for cardiac arrythmias.
- Naloxone hydrochloride - antidote for morphine, pethidine, fluanisone-fentanyl (Hypnorm).
- Doxapram - respiratory stimulant.
- Isoprenaline - for vasodilation.
The examples listed above are by no means exhaustive. You may find many other drugs in practice with a role to play in emergency situations such as cardiac arrest or apnoea.
List instruments and equipment suitable for the emergency box. Every surgery will have variations upon this list and it is important to familiarise yourself with the contents in practice.
- Stop watch.
- Masks.
- Laryngoscope.
- Cuff inflator and tube clamps.
- Suction catheter and connector.
- Endotracheal tubes.
- Tracheotomy tubes.
- Selection of needles and syringes.
- Selection of intravenous catheters.
- Spirit.
- Curved scissors.
- Scalpel blades.
- 2.5cm Elastoplast or zinc oxide tape.
In the evident of an anaesthetic accident, what procedures are to be followed?
- Stay calm.
- Advise the veterinary surgeon.
- Call other staff for assistance.
- Assist with or carry out emergency treatment under the instructions of the veterinary surgeon (remembering the importance of "ABC" - airway, breathing, circulation.
- After the event the details must be recorded accurately on the patient's anaesthetic monitoring form and case notes.
Define the following terms: (i) Apnoea. (ii) Hypoxia. (iii) Hypercapnia.
- Apnoea - cessetion of breathing.
- Hypoxia - inadequate oygenation.
- Hypercapnia - excess blood carbon dioxide (also known as hypercarbia).
List five possible causes of apnoea.
- Intravenous anaesthetic drug overdose.
- Upper airway obstruction
- Acute event such as pneumothorax
- Chest wall fixation or immobility
- Failure of the brain to respond to carbon dioxide or oxygen
List are the signs of apnoea?
- Absence of breathing, although the patient may gasp.
- Staring eyes with dilated pupils.
- Spasmodic diaphragm contractions.
- Neck extended with twitching muscles.
- Blue or grey mucous membranes.
List possible reasons that may cause the brain to fail to respond to oxygen?
- Anaesthetic overdose.
- Hypothermia.
- Increased intracranial pressure as a result of inflammation or neoplasia.
- Severe head trauma.
What is the most common cause of hypoventilation?
Profound anaesthesia. The deeper the anaesthetic, the deeper the degree of respiratory depression.
What clinical signs may be indicative of an airway obstruction?
- Respiratory snoring.
- Paradoxical thoracic wall movement during inspiration (the abdomen moves outwards and the chest inwards).
List possible causes of an airway obstruction.
- Blood.
- Bronchospasm.
- Kinked, damaged or misplaced endotracheal tube.
- Gas.
- Pulmonary oedema.
- Soft tissue.
- Vomit.
Define laryngospasm.
A reflex prolonged contraction of the laryngeal muscles that is liable to occur on insertion or withdrawal of an endotracheal tube. Cats are more likely to be affected than dogs.
List 4 methods of preventing laryngospasm during endotracheal intubation.
- Select the correct sized endotracheal tube.
- Do not over inflate the cuff (and ensure that the cuff is deflated prior to removal of the endotracheal tube).
- Lubricate the endotracheal tube to aid passing.
- Use a topical local anaesthetic spray such as Intubeze (which my boss invented incidentally!).
List possible causes of bradypnoea during anaesthesia.
- Deep anaesthesia.
- Opioids.
- Hypothermia.
- Elevated intracranial pressure.
List possible causes of tachypnoea during anaesthesia.
- Inadequate anaesthesia.
- Pyrexia.
- Hypercapnia (hypercarbia).
- Restrictive lung lesions.
List possible causes of bradycardia during anaesthesia.
- Anaesthetic drug overdose.
- Terminal hypoxia.
- Vagal activity.
- Hyperkalaemia.
- Hypothermia.
List possible causes of tachycardia during anaesthesia.
- Inadequate anaesthesia.
- Hyperthermia.
- Hypercapnia (hypercarbia).
- Hypotension.
- Hypoxia.
- Antimuscarinic drugs.
- B agonists.
List possible causes of arrythmias during anaesthesia.
- Inadequate anaesthesia.
- Anaesthetic drug overdose.
- Electrolyte imbalance.
- Blood gas abnormalities.
- Medical conditions such as gastric dilation (associated with ventricular arrythmias).
- Some surgical conditions.
Why is hypotension a risk during anaesthesia?
Prolonged hypotension diminishes perfusion in the splanchnic and renal vasculature leading to tissue damage. In severe cases, myocardial and cerebral damage may result and prove fatal.
List possible causes of hypothermia during anaesthesia.
- Cold or draughty ambient environment.
- Excess clipping of hair.
- Over-enthusiastic preparation of the surgical site resulting in the patient and/or drapes becoming wet.
- Impaired hypothalamic thermoregulation as a result of anaesthetic drug administration.
- Vasodilation of the blood vessels of the skin.
- The cessation of skeletal muscle activity.
- Inhibited shivering.
- Exposed visceral surfaces.
- Cold, dry inspired gases.
What animals are most at risk from hypothermia during anaesthesia and why?
- Neonates - poikilothermic, underdeveloped and have a high ratio of surface area to volume.
- Young animals - underdeveloped and have a high ratio of surface area to volume.
- Birds - high ratio of surface area to volume.
- Small mammals such as hamsters, rats and chinchillas - high ratio of surface area to volume.
- Reptiles - poikilothermic.
- Geriatrics - impaired thermoregulatory reflexes.
How is the difference between core and periphery temperature measured?
By the simultaneous use of two calibrated thermistors placed at appropriate sites; such as over thebase of the heart via the oesophagus and on the lip.
What should be suspected if darkly coloured, slowly oozing blood is observed at the surgical site?
Poor perfusion.
What are the responsibilities of the veterinary nurse during the recovery period?
- Monitoring of the patient's vital signs (CRT, HR, PR & depth, RR & depth, temp, mm colour).
- Keep accurate records.
- Ensure that the patient is kept warm, clean and dry.
- Attend to any wounds and prevent interference.
- Administer drugs under the instruction of the veterinary surgeon.
- Monitor fluid and energy balance.
- Advise the veterinary surgeon of any problems immediately.
List reasons that may contribute to a prolonged recovery.
- Hypothermia - causes retarded expiration of volatile agents and the redistribution and metabolism of injectable drugs.
- Drugs such as ACP - especially in border collies, brachycephalic breeds and animals with impaired hepatic function.
- Other drug retention - as a result of inadequate perfusion and/or impaired hepatic/renal function.
- Very severe pain - this may result in depression (although excitation is more probable).
- Drug recycling - Immobilon is particularly prone to this.
What may cause excitation during the recovery period?
- Pain.
- Convulsions as a result of conditions such as epilepsy.
- Pharmacological phenomena (eg. after top-ups of thiopentone).
- Environmental factors (eg. light and noise).
List examples of accidents that may be associated with general anaesthesia. Briefly describe your actions in the event of such circumstances.
- Extravascular injection - promptly inject the site with sterile saline or water to dilute the drug and massage (thiopentone is particularly nasty as it causes skin sloughing).
- Drug overdose - Intubate, ventilate (with pure oxygen), cardiac compression if pulse weak or absent, administer drug agonists if available, administer intravenous fluids and inotropes if necessary.
- Hypostatic congestion - this is better prevented; turn the animal frequently (every 2 hours).
- Explosions and fires - raise the alarm, call emergency services, evacuate the premises and follow the fire drill.
- Bites and scratches by patients - seek treatment from the practice first aider and ensure that a report is noted in the accident book, visit the doctor or hospital if necessary.
- Self-administration of drugs - seek medical advice immediately.
List alternative methods of administering oxygen if an animal is not intubated.
- Via face mask.
- Transtracheal catheter.
- Intranasal catheter.
- Tracheostomy tube.