Basic life support is the backbone of veterinary CPR. With basic life support, the veterinary team function as the patient’s heart and lungs, performing chest compressions and ventilation to pump blood to the lungs and other vital organs, allowing gaseous exchange to take place.

The early identification of a cardiopulmonary arrest (CPA) and the rapid onset of compressions and breaths is vital during CPR. Any delay in the onset of resuscitation will mean we are less likely to get our patient back - so today we’re talking how to spot an arrest, and how to perform those basic life support techniques in practice. Ready to learn more? Let’s jump in.

Detecting an Arrest

Cardiopulmonary arrest or CPA is the absence of a heartbeat and the cessation of breathing. Generally, animals go into respiratory arrest first, however, they will progress to a cardiac arrest; therefore, even if they still have a pulse, we still need to intervene as an emergency.

In any unresponsive patient, we need to do an ‘ABC’ assessment to diagnose an arrest. This is a very rapid evaluation which should only take around 10-15 seconds.

Airway

Is it patent, or is it obstructed? If it is not patent, CPR will be unsuccessful. The assessor places their hand in the animal’s mouth and feels for evidence of obstruction. If an obstruction is present, this must be relieved as an emergency - in severe cases, an emergency tracheostomy may need to be performed.

This assessment should only be performed in unresponsive patients, due to the risk of being bitten. 

Breathing

After a patent airway has been confirmed, breathing is assessed by visualising the chest wall, or by placing a hand against the chest wall and feeling for any movement. If the patient is apnoeic, the team can skip the circulation assessment and begin CPR.

Circulation

It is actually no longer recommended to try and feel for a pulse in an apnoeic patient, as an indicator of whether CPR is required. This is because, in up to 35% of CPA cases, the veterinary team have thought they could feel a pulse when one was not present. Pulse palpation is therefore not a reliable indicator of CPA and it is safer to begin resuscitation. If a pulse check is performed, it should not delay starting CPR, so should only take a couple of seconds.

I think my patient has arrested. What should I do?

If you suspect a CPA then the first thing to do is alert your team. Shout out to your team-mates or use a whistle or alarm system to alert everyone. Then stop any medications/infusions being given (as things like analgesic agents will cause cardiovascular & respiratory depression), disconnect any patient lines efficiently and quickly, and move the patient to the CPR area.

NB. In an intensive patient or one with lots of lines attached to them, checking connections and untangling lines should be performed regularly (every 2-4 hours) during hospitalisation. Lines should always be attached to catheters in a way where they are easy to identify and quick to remove; lines should also be labelled at the end of the giving set nearest the patient, as well as on the bag or syringe, to help with this process.

Basic Life Support

Basic life support is the administration of uninterrupted chest compressions and ventilation. It is performed in 2-minute cycles, and at the end of each cycle the patient is very briefly assessed, and the person administering compressions rotates to avoid fatigue.

Chest Compressions

Chest compressions should be initiated first after a CPA is confirmed. Their function is to pump blood to the lungs, and administering effective compressions is vital, as only around 30% of the patient’s normal cardiac output will be generated through chest compressions, even if your technique is perfect. It also takes 1 minute of good-quality compressions to reach the maximum cardiac output you’re going to generate for the patient, so it is important not to switch out of this role earlier than every 2 minutes wherever possible.
To deliver good quality compressions, there are three main things we need to focus on: our posture, our technique, and our compression point.

Posture

When performing chest compressions, you should be positioned with your arms straight and elbows locked, with your shoulders directly over your hands. One hand should be positioned on top of the other, with the heel of your hand over the compression point. Compressions are administered by bending at the waist and engaging your core muscles - so the force comes from your body, through your straight, locked arms, and then into the patient

Technique

Compressions should be administered at a rate of 100-120 per minute, regardless of the patient’s size. There are a number of handy tools to remember the rate, such as keeping to the rhythm of ‘Stayin Alive’ by the Bee Gees, or by using a metronome or smartphone app. 

When performing the compressions, we want to compress the thorax by ⅓ to ½ of the width, whilst allowing the chest to recoil fully after each compression.

Chest compressions must be uninterrupted and should continue for 2 minutes before a new compressor takes over. When switching out this role, the new compressor should move behind and to the side of the current compressor around 10-15 seconds before the 2-minute cycle is up, announce their arrival, and perform a 5-second countdown before switching.

Compression Point

The compression point itself varies based on the size of the patient:

• For round-chested breeds (e.g. labrador) the compression should be given at the widest part of the chest, with the patient in lateral recumbency. This is usually around the 10-11th rib, where the chest wall ‘sticks up’ the most. By compressing here, we are actually altering the pressure in the chest causing more blood to passively flow into the heart, instead of compressing the heart itself.

• For keel-chested breeds (e.g. greyhounds) the compression should be given directly over the heart, with the patient in lateral recumbency.

• For barrel-chested breeds (e.g. bulldogs), these patients should be positioned on their back and compressed over the chest (like human chest compressions).

• For cats, they are positioned in lateral recumbency and the compressions are administered directly over the heart. A one-handed or two-handed approach can be used; if a two-handed approach is used, care must be taken not to over-compress the thorax (by more than ½).

Ventilation

Early endotracheal intubation is very important in animals - this is because cats and dogs generally go into respiratory arrest first, meaning they have less residual oxygen in their system to be circulated via compressions. The patient should be intubated in lateral recumbency, whilst chest compressions continue - an assistant should extend the head forwards parallel with the table and hold the tongue outwards whilst the patient is intubated. The tube should be secured firmly and the cuff inflated appropriately where required.

After an airway is secured, an Ambu bag should be attached to both the ET tube and an oxygen source, and the patient should be ventilated. One breath should be administered once every 6 seconds, to give a respiratory rate of 10 breaths per minute. Each breath should have a short inspiratory time of 1 second - this is important as inspiration increases the pressure in the chest, which reduces the flow of blood back to the heart. By reducing this inspiratory phase, we are maximising the cardiac output we’ll achieve during CPR.

So that’s basic life support! What are your experiences with CPR in practice? Let me know below! Don’t forget to have a read of last week’s CPR preparation post if you haven’t already, and I’ll see you next week for our deep dive into advanced monitoring during CPR!

References and Further Reading

1. Fletcher, D. et al. 2012. RECOVER evidence and knowledge gap analysis on veterinary CPR part 7: Clinical guidelines. Journal of  Veterinary Emergency and Critical Care, 22 (S1), S102-S131.

2. Haskey, E. 2016. CPR: Basic life support. The Veterinary Nurse, available from: https://www.theveterinarynurse.com/review/article/cpr-basic-life-support

3. Hopper, K. et al. 2012. RECOVER evidence and knowledge gap analysis on veterinary CPR part 3: Basic life support. Journal of  Veterinary Emergency and Critical Care, 22 (S1), S26-S43.

4. Yagi, K. 2017. Critical Components to Successful CPR. Today’s Veterinary Nurse, available from: https://todaysveterinarynurse.com/articles/critical-components-to-successful-cpr-the-recover-guidelines-preparedness-and-team/