Emergencies are unexpected events that require immediate action for success. Genuine equine emergencies are rare, but when they occur they are stressful for everyone.

Pressures

Our actions in an emergency are influenced by adrenaline. Muscle tension, perspiration, lack of clear thought and a decrease in group focus make dealing with emergencies more difficult.

They are often dangerous, and acceptance of risk alters when under pressure. Professional standards can also be modified – we often ‘muddle though’ emergencies, when at other times that isn’t acceptable.

Preparation is the key. The better prepared the individual, the better the team will perform and team performance is critical to outcome. Emergency situations should be rehearsed as often as practically possible. For a typical equine practice the more ‘common’ emergencies should be rehearsed annually.

Clear guide cards should be printed for different situations and kept close at hand. They will act as a useful prompt when the mind goes blank under pressure.

Personal and team safety is essential. The veterinary profession is unusual because nurses and vets can be thrown into potentially life-threatening situations without specific emergency training. If you find yourself in a situation where you are unhappy about your own safety, then tell someone immediately and remove yourself from the situation.

If the owner is present, remove him or her from potential danger as soon as possible. Approximately 80 per cent of the public would risk their lives for an animal. Don’t allow this to happen if you are able to prevent it.

Cardiac arrest during anaesthesia

If your practice performs regular equine anaesthesia using inhalation agents, then at some stage you are likely to face a cardiac arrest. Lengthy anaesthetic procedures and operations performed late at night or over weekends make cardiac arrest more likely.

In critically ill patients, revival might not be justified, if there is already a very poor prognosis for survival. However, Taylor and Clarke suggest that otherwise healthy horses can survive anaesthetic-associated cardiac arrest up to 50 per cent of the time.

Speed of detection is vital for survival, and continuous ECG monitoring is required to detect cardiac arrest at an early stage. Other slower warning signs include loss of palpable pulse, loss of arterial wave form on arterial blood pressure traces, loss of corneal reflex and very low end tidal CO2.

On the ECG trace, cardiac arrest will most commonly be preceded by an irregular sinus rhythm. This is recognised by slow, irregularly spaced QRS complexes. If you see these, always notify the anaesthetist that there may be a problem. Irregular sinus rhythm can lead to asystole (flat line), which is by far the most common cause of cardiac arrest in horses.

Rarely, ventricular fibrillation (a chaotic wobbling line) occurs and in these cases resuscitation is hardly ever successful.

Resuscitation procedure

If resuscitation is to be attempted, everyone must be told that there is a problem. The time should be noted. Because so much needs doing, responsibilities should be assigned to at least three people:

P1. someone to assist the surgeon,

P2. someone to help the anaesthetist, and P3. a runner to fetch and carry equipment.

Activities for each individual could then be assigned as follows:

P1. Cardiopulmonary resuscitation (CPR) is not possible until the patient is in lateral recumbency. An open abdomen must be closed as quickly as possible and any surgical area covered to maintain sterility. The patient should be lowered to the floor and any thick padding removed.

P2. The volatile agent must be turned off immediately. A high rate of 100 per cent oxygen is required, and the rebreathing bag should be emptied and refilled regularly throughout resuscitation. You should then assist with ABC(D) checks, CPR or drawing up of drugs as advised.

P3. The ‘crash’ box should be fetched and opened. Instructions and doses will be required. Other equipment may be needed, so a runner should remain available throughout.

ABC(D) basics Airway

Intubate or assist in intubating the patient, if not already done. Check that the endotracheal tube is not blocked and check the anaesthetic circuit.

Breathing

Start intermittent positive pressure ventilation (IPPV), giving 10-20 breaths per minute.

Circulation

Give maximal fluid support.

CPR is attempted by standing just behind the forearms of the recumbent animal and falling onto the side of its chest just behind the elbow with your knees, thus compressing the heart/thorax in an attempt to create movement of blood.

This should be done up to 80 times a minute and continue while there are signs of brain activity, until normal circulation resumes. This procedure is physically exhausting, so take turns.

Drugs

Cardiac drugs should not be given until CPR is being performed. Because asystole is the most common cause of cardiac arrest, the drugs regimen normally used in resuscitation is in Table 1.

If spontaneous circulation is established and maintained, then the patient must be put into recovery as quickly as possible. This may mean finishing the surgical procedure, or simply closing any wound and ending the procedure immediately. Close monitoring should be continued throughout recovery, and the crash box should be restocked immediately.

The critical colic

In equine practice, you may occasionally be faced with critically ill colic cases that require assessment and preparation for surgery. These patients are often in pain, anxious and dangerous. They may arrive recumbent and require ‘rescuing’ from their transport before anything can be done.

Their owners are often tired, emotional and demanding. The patient must be moved to the safest place for assessment. Once the horse is safe to handle, immediate nursing support will be required.

Clinical examination of these patients can be difficult. They typically have rapid, weak and thready pulses, toxic mucous membranes, no gut sounds and severe hypovolaemia. It can be difficult to place an intravenous catheter, but fluid support is essential. The patient may become calmer after gastric reflux, and a gastric tube should remain in place throughout any anaesthetic.

There are occasions where you may have to anaesthetise the patient before stabilising it, but try to avoid this because hypovolaemia and myocardial depression, caused by toxaemia, may prove fatal. If possible, give 4 to 6 ml/kg of hypertonic saline as fast as possible intravenously, followed immediately by isotonic saline – to be continued throughout anaesthesia.

Once anaesthetised, these patients should receive IPPV and dobutamine immediately. Remember to continue cardiovascular support throughout the recovery period.

Field emergencies

As an equine nurse, you could be called upon to assist at any sort of field emergency, at any time – from a road traffic accident to a serious barn fire, to a horse trapped in a potentially dangerous situation. If there are fire crew, ambulances or police in attendance, then it is likely that you and the veterinary surgeon will be the professionals at the scene with the
least emergency training.

Despite this, because an animal is involved, the expectations on you could be high. Most veterinary surgeons will have had no formal emergency training at university, and the emergency services may have had no experience in handling horses at all.

Hampshire Fire and Rescue Service and the British Equine Veterinary Association (BEVA) have now started training courses for safer horse rescues for vets and fire crews. These courses offer superb value for money and if you can get a place,

I would highly recommend them to any nurse who wants to gain confidence in the safe handing of horses in difficult and dangerous situations.

The Safer Horse Rescues DVD is available at www.vets.tv and is recommended for anyone in equine practice.

There are three golden rules to follow in any equine rescue:

•   do not attempt to move a horse until a head collar/halter is on the animal

•   never release a trapped animal unless you have a safe place for it to go

•   always make sure you have a safe escape route.

Keep yourself in a safe position, especially when a trapped horse senses ‘freedom, as this is often when it is most likely to panic.

Author

Ben Portus BSc BVSc MRCVS

After graduating from Bristol University in 2003, Ben went to Finland for three months to gain experience of equine stud medicine. He returned to Essex for a while, and then took an internship at Rossdale & Partners in Newmarket, before becoming a partner himself at Paton and Lee. He has given lectures on equine anaesthesia to veterinary nurses at Writtle College and, more recently, at the BVNA congress in Kettering.

Reference

1. TAYLOR, P. and CLARKE, K. W. (2007) Handbook of Equine Anaesthesia, 2nd edn. Saunders/Elsevier

Veterinary Nursing Journal • VOL 25 • No1 • January 2010 •