Most veterinary patients will develop CPA due to progressive systemic illness, trauma or other processes resulting in hospitalisation. The best method to improve survival from CPA is to prevent it from occurring in the first place. Successful CPR relies on good preparation and teamwork; this involves early recognition of, and a quick response to, impending arrest. Nurses often have a critical role in this care as they spend the majority of the time with the patients at risk, so their observations can make all the difference in vital situations.
Ideally, there should be access to a well-stocked crash box, containing all the likely equipment required to run a successful resuscitation attempt (see Table 18.3). One member of the team should have the responsibility of checking the crash trolley/box on a daily basis. Team members should have practiced the necessary techniques on a regular basis so that CPCR can be commenced as quickly as possible. Resources should include a central treatment room/arrest station with a hard surfaced table, stools for compressors to stand on, crash trolley with consumables and medications, oxygen, airway and ventilatory equipment, electrocardiography (ECG) with or without defibrillation, monitoring equipment, protocol flow charts and drug dose charts (see Figure 18.2). Maintain equipment and supplies with a daily checklist. CPR ‘practice’ sessions are essential in having a well-rehearsed, coordinated team; sessions should be carried out on a regular basis so any weaknesses can be identified.
|Endotracheal tubes (range of sizes 2.5–14 mm)|
|Anaesthetic breathing systems|
|Assorted intravenous catheters|
|Assorted hypodermic needles|
|Lactated Ringer’s solution|
|Pressure bag for rapid infusion of fluids|
|50% dextrose solution|
|Polyurethane urinary catheters|
|Tracheostomy tubes (range of sizes)|
|4% chlorhexidine gluconate or 10% povidone–iodine|
|70% surgical spirit|
|Electrocardiogram monitor, leads, clips and conduction gel|
|Emergency drugs, e.g. adrenaline, atropine|
|Sterile gauze swabs|
The Resuscitation Team
A CPR requires a team of individuals operating efficiently and with excellent communication. A minimum of two personnel is required for effective CPR. The ideal team consists of:
If additional personnel are available, the following additional roles may be assigned:
The team leader is the individual directing the CPR process. The compressor is responsible for chest compressions and should rotate every 2 minutes with the breather to prevent tiredness and ineffective technique. The breather is responsible for ventilations and should rotate every 2 minutes with the compressor. The drug administrator draws up and administers drugs as directed by the leader, and should anticipate needs and draw up drugs that may be required in advance. The recorder maintains a record of everything that is done including timing, monitors cycles of CPR (every 2 minutes) and announces the end of each cycle, and keeps track of frequency of drug administration, suggesting when administration should occur.
Effective communication is essential for a successful resuscitation effort. Roles of all team members must be clearly defined. A leader must be identified immediately, and subsequently quickly assigns roles to the other team members. Clarity of communication is another key concept. All messages should be specifically directed at an individual, and requests should be clearly and succinctly stated. Orders should not given ‘to the room’, but directed at an individual, with that individual responding that he/she understands.
Resuscitation at the cellular level requires oxygen delivery to the vital organs. In recent years the sequence of Airway–Breathing–Circulation has been changed to Circulation–Airway–Breathing in all but known asphyxial causes. This allows for compressions to be initiated earlier on; this is vital when faced with a difficult airway or gathering supplies. Supporting arguments for this change in sequence to C–A–B state that during low blood flow states such as CPR, oxygen delivery to the heart and brain is limited by blood flow rather than by arterial oxygen content. Therefore, compressions are more important than ventilations during the first few minutes of resuscitation. Additionally, chest compressions cause air to be expelled and oxygen to be drawn in passively through the elastic recoil of the chest. This, in theory, may help maintain a higher arterial oxygen saturation until positive pressure ventilation can be initiated. Routine pulse checks have been de-emphasised due to the difficulty in assessing the absence or presence of pulses, even for experienced personnel. Any delays for pulse checks should be no longer than 10 seconds. Checking for pulses during compressions is not indicated. Remember that the lack of valves in the inferior vena cava allows retrograde blood flow within the venous system and therefore may produce pulsations that have no clinical relevance. One useful technique for assessing pulses during CPR is to place a well-lubricated Doppler probe on the cornea, as this, along with ECG monitoring, will help detect the return of spontaneous circulation (ROSC) (see Figure 18.3).
The guidelines in Table 18.4 have been formulated to optimise blood flow with the intent of perfusing the heart and brain. During CPR efforts, cardiac output is approximately 25–33% of normal, so optimising compressions is important. Compressions are performed using two different methods based on patient size. In smaller patients (<7 kg), it is feasible to directly compress the heart (cardiac pump theory) between the ribs (see Figure 18.4). In larger patients, forward blood flow is related to changes in intrathoracic pressure that is transmitted to the major vessels (thoracic pump theory).
Place your patient on a rigid surface, generally in lateral recumbency, and supported as needed to provide a stable compression surface. Dorsal recumbent positions may be used dependent upon a patient’s chest conformation (see Figure 18.5). For small patients, place your hands directly over the heart for compressions at a rate of at least 100/minute. In larger animals, hand position is at the widest part of the thorax, lock your elbows (see Figure 18.6). This is important to ensure maximal pressure is applied) and apply even pressure through the heel of your hand (see Figure 18.7). Compressors will probably have to stand on a footstool in order to gain sufficient height to perform compressions effectively. ‘Push hard and fast’ means a 1 : 1 ratio of compression to relaxation, allowing for complete chest recoil. Incomplete chest recoil has been associated with increased intrathoracic pressure and decreased perfusion. Compressions should be performed in 2-minute cycles with the break in between each cycle <10 seconds. This break time is used for checking pulses, ECG assessment, defibrillation or performing a difficult intubation or catheter placement. After each 2-minute cycle, rotate compressors. Fatigue is commonly seen in compressions performed by a person for longer than a 2-minute cycle, which leads to decreased effectiveness.