Cardiopulmonary Resuscitation Practical for Nurses

When to Resuscitate

• Many factors need to be considered when deciding if to proceed with resuscitation of the patient depending on the patient’s condition, financial concerns, post CPR care, etc.
• What is the potential outcome of CPR? Does the patient have such extensive injuries that chance of full recovery from them is already compromised?
• What have you agreed with the owner We must honour their decisions, whether we feel they are correct or not.
• Does the patient have a treatable disease?  If we resuscitate the patient, can we treat/cure the underlying disease/problem?
• Is the patient in the terminal stages of an incurable disease? - e.g., cancer, renal failure etc
• We must consider if we will be able to restore a near-normal mentation.
• When did the arrest occur? Have we suffered brain damage due to prolonged hypoxia, etc.? We can get a heart back, but we cannot resolve brain damage from hypoxia.

Your clinic may have a classification system on when or not to resuscitate. As part of the Recover guidelines the following system was derived:

Vital Signs

Vital signs are, as they are called “vital” in assessing a patient’s condition and status. All staff must know the normal ranges for the species they are treating.

Order of Priority and Team Roles

The patient has arrived, a quick visual assessment has been completed and the patient is in a critical condition. What do you do now and in what order?

First, establish if the patient is in just pulmonary arrest (not breathing) or cardiopulmonary arrest (not breathing and no heartbeat).

Use the acronym CAB:

• C – Circulation - No heartbeat, audible heartbeat or pulse then start compressions
• A – Airway - Check for a patent airway and provide oxygen supplementation or intubate
• B – Breathing - Start intermittent positive pressure ventilation

Circulation is the most important priority when starting CPR. It has been shown that there will be potentially enough residual oxygen in the body for up to 3 minutes post arrest but in a cardiac arrest that oxygen is not going anywhere so we need to start compressions immediately to help with circulation. Then, ensure a patent airway and intubate to provide oxygen supplementation or start intermittent positive pressure ventilation (IPPV). Compressions should never be stopped for intubation.

If you are in the unfortunate circumstance of being the first responder to a patient in cardiac arrest and do not have any assistance the first priority is to start chest compressions. If after 3 minutes you are still the only responder then stop compressions to intubate and breathe for the patient in between compressions. 2 breaths to every 30 compressions.

All staff available in the hospital should assist with CPR. Often I have seen Vets or Nurses come in to the room and see ventilation and compressions occurring and someone getting drugs and they think there is nothing for them to do. Even if you aren’t taking an active role in performing CPR, recording all the actions taken such as

start time of CPR and timing the 2 minute cycles along with all observations and drugs administered is very important. Roles that each team member can perform are:

Compressions - This is performed in 2 minute cycles. It is important that this person swaps out this role to another team member after each cycle as performing compressions is tiring and compressions will not be effective after this time.

Airway and ventilation - This person could swap with the team member performing compressions and vice versa.

Circulation - Placing an IV Catheter and collecting and administering drugs and fluids

Monitoring - Attaching monitoring equipment and performing observations and monitoring vital signs. Communicate what you are observing and how effective is the CPR being performed.

Recording - Recording all actions, drugs administered with doses and time, time CPR was started and time the 2 minute cycles of CPR.

Compressions

Cardiac arrest will shortly follow respiratory arrest often if not occurring at the same time. Cardiopulmonary arrest occurs when cardiopulmonary function fails. The aim of cardiopulmonary resuscitation is to restore cardiac function and circulation. This is done by creating adequate pressure in the thoracic cavity by compressing the chest wall to stimulate cardiac output and create adequate venous return. There are two ways of performing cardiopulmonary resuscitation, external cardiac massage and internal cardiac massage.

External Cardiac Massage

There are two methods of external cardiac massage depending on the size of the animal.

Patient positioning - Experimental evidence suggests higher left ventricular pressures and aortic blood flow in dogs in lateral recumbency compared to dorsal recumbency and higher rates of return of spontaneous circulation in compressions performed in lateral recumbency suggest that this is the ideal position. Either left or right is now considered acceptable, although right lateral is preferred. However there are great variations in chest conformation among dogs and cats so a single identical approach to compressions is unlikely to work.

Cardiac Pump (Patients Under 20 kg)

The cardiac ventricles are directly compressed between the sternum and spine in patients in dorsal recumbency and between the ribs in lateral recumbency. This method is most suitable for patients weighing less than 20 kg.

The patient is placed in lateral recumbency and the chest wall is compressed by placing both hands on the upper side of the chest wall at a rate of 100–120 compressions per minute. The chest should be compressed to 30–50% of its circumference. In very small patients such as cats the chest can be compressed between the thumb and forefinger with the thumb being on the upper side of the chest wall. Ventilation is given simultaneously with compression at 1 breath every 5 seconds. Continue the cycle for 2 minutes without interruption.

Thoracic Pump (Over 20 kg)

Chest compressions increase the overall intrathoracic pressure, secondly compressing the aorta and collapsing the vena cava leading to blood flow out of the thorax. During the elastic recoil of the chest, sub atmospheric intrathoracic pressure provides a pressure gradient that favours the flow of blood form the periphery back into the thorax and into the lungs where oxygen and carbon dioxide exchange occurs.

This method is most suitable for patents weighing over 20 kg or medium, large or giant breeds with round chests. The patient can be in lateral or dorsal recumbency. The chest is compressed to 30–50% of its circumference by placing both hands on the widest point of the chest. Ventilation is simultaneously supplied to increase the thoracic pressure also at 1 breath every 5 seconds. Continue the cycle for 2 minutes without interruption.

Abdominal Counter Compressions

Abdominal counter compressions can help with venous return and improve cardiac output. By applying abdominal compressions alternate to chest compressions the blood is forced to the chest cavity for more effective cardiopulmonary resuscitation. If abdominal compressions are not possible, then binding the hind limbs and abdomen with bandages (Vetwrap) helps to create the same effect. There have been some reports of injury to abdominal organs in some cases when counter compressions are applied. Therefore this is often used as a last resort method.

Internal Cardiac Massage

This method is not common, as it involves opening the chest and hence a surgical approach. Clip the hair on the chest between the sternum and chostochondral junction and apply a quick surgical scrub. The veterinarian will make an incision between the 4th and 5th ribs and spread them apart with retractors while delicately moving the lungs. The pericardium is then grasped and the heart compressed with a thumb and forefinger. It is important that IPPV is maintained throughout this process.

Airway

Look at the animal! If the respiration rate is slow and the mucous membrane colour is pale to grey then respiratory arrest is often not too far off. Agonal gasps are generally a clear indicator of cardiac arrest or imminent arrest. Ensure a patent airway. Wipe or suction away any debris in the mouth and airway such as blood, vomitus or foreign objects.

Breathing

If the animal is in actual respiratory arrest (not breathing at all) then an appropriate sized endotracheal tube must be placed down the trachea and the cuff inflated. Attach the tube to an oxygen source which ideally would be an Ambu bag but the anaesthetic machine is adequate however ensure the vaporiser is turned off and the circuit closed. Commence intermittent positive pressure ventilation (IPPV). One breath every 5 seconds at a tidal volume of 10 ml/kg. If you can monitor ETCO₂ with a capnograph a measurement of at least 15 mm Hg will give an indication that ventilation provided is adequate.

CPR Cycle

An uninterrupted cycle of basic life support lasting 2 minutes in intubated patients is recommended before checking for vital signs. If mouth to snout 2 minute cycle however 30 chest compressions with brief interruption to allow 2 quick breaths. Rotate personal doing chest compressions after each 2 minute cycle as it is very tiring and your compressions will not be effective after this time. If you feel you are tiring before the two minutes is up speak up and swap with another team member immediately.

ECG

An ECG being placed is often classed as Advanced life support but it will tell us about the electrical activity of the heart in particular if we have ventricular fibrillation occurring.

PQRST Complex

The PQRST complex can tell us what is happening within the heart.

P wave indicates atrial depolarisation (atrial contraction).

QRS wave indicates ventricular depolarisation (ventricles contracting).

T wave indicates repolarisation (heart relaxed).

Defibrillation

Ventricular fibrillation is an irregular quivering motion of the ventricles caused by continuous disorganised electrical activity in the heart. An ECG trace will show no QRS complexes. Without co-ordinated contractions the blood is not propelled forward. The idea of a defibrillator is to depolarize the myocardial cells in the ventricles or to shock them into their refractory period and allow the pacemaker of the heart to start a normal sinus rhythm. If a defibrillator is not available a pre-cordial thump on the chest over the heart can be used although this is likely to not be very effective.

Conclusion

We only have 3–5 minutes to restore cerebral and coronary perfusion so we must act quickly but not panic. If you understand your role, work well as part of a team who practices CPR regularly and perform the necessary steps of CPR the patient has a greater chance at a positive outcome.

To access the Recover CPR Guidelines go to http://onlinelibrary.wiley.com/doi/10.1111/vec.2012.22.issue-s1/issuetoc.

References

1.  Journal of Veterinary Emergency and Critical Care. 22 (s1) 2012. Recover Emergency and Critical Care Guidelines on CPR.

2.  Lesley G. King, Amanda Boag. BSAVA Manual of Canine and Feline Emergency and Critical Care. 2nd Edition.

3.  Donald C. Plumb. Plumbs Veterinary Drug Handbook. 5th Edition.

4.  Animal Industries Resource Centre - Veterinary Nursing Technician Notes (CTVN L3) Emergency and Critical Care

5.  Vetlearn Veterinary Technician. August 2012 Volume 33, Number 8.

6.  Amy Breton, CVT, VTS (ECC). “Cardiopulmonary Resuscitation: Administering fluids, oxygen and drugs.”