Cardiopulmonary Resuscitation (CPR) in Dogs and Cats

Despite CPR not being a procedure we perform very frequently, it was only a few weeks ago that myself and a team of dedicated vets and nurses performed CPR on an already sick dog. We managed to successfully resuscitate this patient but sadly went on to lose him several hours later. Last week’s webinar presented by Fiona Strachan BVMS CertVA MRCVS stated this was always going to be the most likely outcome in any patient which is not anaesthetised and undergoes cardiopulmonary arrest and CPR. Statistics state that despite an initial 58% survival rate post initial CPR there is only a 3-6% survival rate to discharge in dogs and a 2-10% rate in cats. However, these figures differ significantly in patients which undergo cardiopulmonary arrest and CPR whilst under anaesthesia with a survival rate to discharge of nearly 50%. Given some techniques employed during CPR can be highly invasive. A question which needs to be asked is whether a ‘blanket’ approach to CPR should be performed in every case? For example, should all cases undergo open chest CPR or should this procedure be reserved for certain cases? Is it appropriate to perform CPR in an aged dog with metastatic neoplasia or would it be sensible to discuss a ‘do not resuscitate’ order with the owner? Of course, not all cases are ‘black and white’ and some may well have undiagnosed conditions which have led to their cardiopulmonary arrest. Fiona explained these are always difficult decisions to make and often there is no right or wrong answer, it is just important we consider all options available and choose the most appropriate for each situation.

The sick dog we resuscitated a few weeks ago had an undiagnosed condition and for this reason I believe our decision to perform CPR was justified. The whole team did a brilliant job reviving this dog but I’m sure there were areas we could improve upon given we were all a little ‘rusty’ having not performed CPR on a regular basis. In all honesty, I can’t remember the last CPR training session I participated in within practice and this was also the experience of many within this webinar’s live attendees. One of the main take home messages I have learnt from this webinar is how crucial it is to perform regular practical CPR training sessions (at least every 6-12 months if possible). To aid with training, there is now a set of guidelines available called RECOVERY which could be used as a base from which to formulate your own personalised practice protocol. These guidelines were based on a CPR literature review performed in 2012 and are set to be updated every five years. Given our CPR protocols prior to 2012 were based on evidence delivered in the late 1800’s and early 1900’s, these are a set of guidelines well worth taking note of.

This webinar is another excellent resource from which to obtain an up to date knowledge base and formulate a CPR protocol and training plan for the whole team. Fiona discussed in depth each of the stages of CPR: A-airway, B-breathing, C-circulation, D-drugs, E-electrical defibrillation and F-follow up. I could not do Fiona justice by trying to deliver the vast expanse of information offered within this webinar, but I can let you know about some little gems offered up along the way. For example, when trying to secure an airway by intubation, capnography can be useful in determining the correct placement of the endotracheal tube. However, it is important to remember that CO2 levels may be lower than normal as the lack of circulation will reduce the amount of CO2 transported from the tissues. Once an airway is secured, Fiona advised delivering no more than ten breaths per minute as an increase in this figure has been associated with a poorer prognosis. Closed CPR is usually performed to aid in circulation and compressions are usually performed at a rate of 100-120/min. It is advised to change the person performing compressions every two minutes to prevent tiring. However even high-quality compressions only produce 20% of normal cardiac output and this figure can be improved upon by performing a number of techniques which increase blood flow. For example, abdominal binding involves tightly bandaging the hindlimbs, pelvis and abdomen of a patient to increase venous return and increase blood flow.

Fiona also discussed advanced life support which involves the use of drugs and electrical defibrillation. In order to benefit from these interventions, an ECG of a patient undergoing cardiopulmonary arrest is necessary. Usually there are four rhythms which are likely to be detected: pulseless electrical activity (PEA), asystole, ventricular fibrillation and sinus bradycardia. Fiona gave examples of each of these rhythms on ECG and explained which of the drugs usually available in the emergency box (epinephrine, atropine and lidocaine) are most appropriate to use for each rhythm. As it happens epinephrine (adrenaline) can be useful for all four rhythms and is therefore an appropriate drug of choice where no ECG is available, or a rhythm is difficult to identify. Atropine is usually indicated for asystole, PEA and sinus bradycardia with lidocaine reserved for ventricular tachycardia and refractory ventricular fibrillation. However, if ventricular fibrillation has been present for five minutes or more it is likely to be refractory to all drug intervention and only an electrical defibrillator will be of use. Fiona went through its use in detail and despite the majority of the audience not having access to an electrical defibrillator in practice, this may be an area of change in the future.

As stated earlier, these are only snippets of information delivered by Fiona within this webinar and if you really want to improve your knowledge base on this subject matter then watching this webinar is the only way forward. The top tips really do just keep coming, even in the follow up stage when one assumes the drama is all over, monitoring of patients is vital especially given the statistics on survival rates to discharge given earlier within this blog. Human studies have shown that mild hypothermia has been beneficial in terms of survival for patients post CPR and for this reason rapid warming of our patients on recovery is advised against. Mild hypertension can also be of benefit and blood pressure should be monitored on a regular basis.

Having experienced our team resuscitating a dog which had gone into cardiopulmonary arrest, I realise how well we all work together and the excellent knowledge base our vets and nurses have. However, this does not mean we should rest on our laurels as new evidence is always emerging and advice and guidelines continually change. Regular training and updates are key and watching this webinar is an excellent way to start this all-important process.

Cardiopulmonary Resuscitation (CPR) in Dogs and Cats

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