Cardiopulmonary resuscitation (CPR) is performed when patients experience cardiopulmonary arrest (CPA). In veterinary medicine this is something that has to be performed on a variety of species and sizes of animals. In a survey, it was found that 1.6–6% of dogs and 2.3–9.6% of cats in a veterinary hospital survived CPA to discharge, this is significantly lower compared with 24% of adult human survival to discharge with in-hospital CPA (Gillespie et al, 2019). This review on CPR training discusses research and studies in human medicine as there are currently no studies within veterinary medicine on how frequently CPR training should be undertaken. This suggests there is a knowledge gap within veterinary medicine. Retaining skills and knowledge of CPR are important to patient outcome, and the research in human medicine on skill retention and human intervention is likely to also be relevant to veterinary medicine.
Cardiopulmonary resuscitation skill performance measurement
Cardiopulmonary resuscitation (CPR) skill performance can be measured using a manikin (Mokhtari Nori et al, 2012); in Mokhtari Nori's (2012) study CPR skill retention of hospital staff was measured. Participants were provided 100 minutes of practical training exercises with the manikin, and a CPR skills checklist was used to assess the psychomotor skills of participants. The checklist used was approved by the Irish Heart Association (2000) as a valid CPR skill assessment. The checklist analysed chest compression depth, rate and recoil as well as looking at defibrillator use. The statistics of the psychomotor skills showed a large increase in ability after training; before training 18.7% of 112 participants scored success rates in psychomotor skills, compared with 82.50% 10 weeks after training. Although this study showed the ability of participants to perform CPR increased following training, it did not specify when participants previously had training in CPR. Psychomotor skills were tested again 2 years post training with 42 of the participants taking part. These results showed that 36.81% retained CPR skills — the sample size for this part of the study is smaller than previously, which may have affected the results.
An earlier study by Kaye et al (1990) found that skills significantly dropped only 5 months after CPR training, suggesting that anything longer would also show a decline.
Cardiopulmonary resuscitation knowledge rentention
The Mokhtari Nori et al (2012) study also tested retention of CPR knowledge using a multiple-choice questionnaire. Pre-training, 54.75% of participants answered the knowledge questionnaire correctly and this increased to 80.60% 10-weeks after training. Again, the final re-test was 2-years after training with only 42 participants. This demonstrated that compared with psychomotor skills knowledge is retained better over time. Another study by Bhatnagar (2017) showed that knowledge on CPR after a 6-month period can deteriorate to what it was prior to initial training.
Cardiopulmonary resuscitation skill retention and retraining
Similar to the Mokhtari Nori et al (2012) study the Sand et al (2021)study demonstrated that retraining can help with skill retention, although the study was shorter, and retraining was done at 2-months which may suggest that a longer interval between training and a longer study may have also shown that not having regular training can impact skill retention. In addition to this there is evidence that shows that monthly training is more beneficial than quarterly training (Anderson et al, 2019).
The method used by Sand et al (2021) for testing is not discussed in detail, although the instructor-led training comprised theory and practical training. The theory in this study is not tested as it was in the Mokhtari Nori et al (2012) study, which included a multiple-choice questionnaire in testing, and does not show any advantage on knowledge retention in regular retraining. The skill retesting in Mokhtari Nori et al (2012) and Berden et al (1993) all used manikins in training and retesting — two used manikins with voice feedback, , this helps inform the participants if their compressions are efficient (Mokhtari Nori et al, 2012; Sand et al, 2021), and one used a manikin with no voice feedback (Berden et al, 1993).
Berden et al (1993) started with the largest cohort for the study into skill retention of CPR, 141 medical staff from a teaching hospital took part in the first part of the study. All participants were invited back for a retraining and testing, although only 96 of the original 141 returned for the 12-month testing. This may have impacted the results. Again, retraining was given at intervals for participants, the cohort was randomly put into three groups of training. Group A had retraining every 3 months, group B every 6 months and group C every 12 months. The method used to analyse the frequency of training needed to maintain skills used a manikin — in the first training session the cohort performed 2 minutes of CPR, and during the 2 minutes what was deemed the essentials were recorded for 30 seconds (this consisted of compression rate, depth, ventilation volume and breathing interval). Again, compression depth was analysed as an important part of CPR and retaining that skill is vital for efficient CPR (Yagi, 2017; Oh and Kim, 2018).
Berden et al (1993) found that all participants showed a diminishing skill for CPR before their second training regardless of whether they were in group A, B or C. The study did however find that groups retrained at 3 and 6 months retained the skills for CPR after their second training session, suggesting that 12 months between training sessions would be too long to retain a good skillset for effective CPR. The RECOVER guidelines also suggested that ‘mock-codes’ are best performed every 3–6 months also on manikins (Fletcher et al, 2012), suporting Berden et al's (1993) findings (Figures 1).
The studies all demonstrated that retraining frequently is important and can be the best way to maintain knowledge and skills for CPR, although there are no studies specific to veterinary medicine as the studies are analysing human staff. The methods used for the studies varied but had similar variables with retraining at different intervals, the time between training for best retention is also discussed with each concluding that anything more than 6-months causes staff skill retention to deteriorate. Both Berden et al's (1993) and Mokhtari Nori et al's (2012) studies ended with fewer participants, which may have impacted the results.
It can be concluded from the Mokhtari Nori et al (2012), Berden et al (1993) and Sand et al (2021) studies that frequent retraining of CPR is beneficial to retaining CPR skills to an efficient standard, and as discussed in the RECOVER guideline training should be taken every 3–6 months (Fletcher et al, 2012).
Survival rates post resuscitation
Sand et al (2021) discussed survival rates of resuscitated patients improving over decades, and suggested that ‘high-quality’ CPR is helping the outcome of patients in arrest (Sand et al, 2021). This study used different training methods as well as frequency of retraining. Three different methods for training skill stations were used with different sections of a training environment and varying training equipment: without a human instructor; skill station without a human instructor with repeat training 2 months later; and instructor-led training. Each control group were tested at 2 months and 8 months. The results discussed compression quality and ventilation quality in detail, and showed that compression depth at the 8-month testing in those that had retraining at 2 months averaged 47.8 mm and in those who received simulation training without retraining averaged 46.6 mm (Sand et al, 2021). Although there is only a small difference in compression depth, it is a vital part of CPR, and maintaining a good depth is essential to ensuring survival post arrest (Oh and Kim, 2018). For a veterinary patient, chest compressions are ideally a third to one half of chest width during CPR (Yagi, 2017).
KEY POINTS
- Cardiopulmonary resuscitation (CPR) retraining is recommended every 3–6 months.
- Frequent retraining can help with knowledge and skill retention.
- There are studies to suggest that frequent retraining has helped with survival rates of patients in human medicine.
- Without frequent training skills and knowledge of staff can diminish over time.
- There may be barriers with implementing this in practice, time restraints and cost limitations as well as staff willingness.
There is a significant difference in patient outcome in human and animal patients: in human medicine 33% of patients survive to discharge (Widestedt et al, 2018), while in veterinary medicine 1.6–9.6% of dogs and cats survive to discharge (Gillespie et al, 2019). There may be multiple factors contributing to the lower survival rate of veterinary patients, there is however evidence in skills being improved and retained in human medicine by regular retraining. The retraining impacts specific skills such as chest compression depth, which is the correct depth shown to play an important role in patient survival in human patients (Oh and Kim, 2018; Sand et al, 2021).
Analysing knowledge retention
Methods used for analysing knowledge retention were similar in each of the papers examined, Mokhtari Nori et al (2012) however used a multiple-choice questionnaire as well as retesting psychomotor skills. This is important to see how well knowledge on CPR is retained, having the theory and knowledge to perform CPR appropriately. A questionnaire appears to be a popular method to analyse knowledge retention, and could be easily implemented in veterinary practice to monitor staff knowledge. Retraining is recommended at between 3 and 6 months in multiple studies (Berden et al, 1993; Fletcher et al, 2012; Anderson et al, 2019).
Implementing retraining in practice
The studies show a knowledge gap in the need for CPR training within veterinary medicine, and the RECOVER guidelines discuss this knowledge gap (McMichael et al, 2012). Multiple studies discuss how frequently retraining should occur, however what is not discussed is whether this is enforced in either human or veterinary hospitals. In addition, the best way to implement frequent training is not mentioned in summaries or conclusions.
One study into CPR skill retention found that monthly retraining was optimal to 3, 6 or 12 monthly training (Anderson et al, 2019). It could be argued that monthly training is not something many hospitals and practices would be able to implement. Barriers to implementing change in practice include staff willingness for change and learning as well as confidence in the new task (Geerligs et al, 2018). Although this is not specific to veterinary medicine or CPR training, it may suggest reasons why retraining may not be included or is difficult to introduce into veterinary hospitals. Implementation of new protocols in practice can be also be taxing on staff by creating more work with more to learn and to consider (Geerligs et al, 2018), and this may also be a reason to not enforce frequent training (Figure 2).
Conclusion
The evidence strongly suggests that retraining is necessary to retain skills, as veterinary patient survival of CPR to discharge is lower than human survival rates (Gillespie et al, 2019). This may mean there is a chance of improvement if regular retaining is enforced in veterinary hospitals. The use of knowledge testing would also be beneficial, to monitor what knowledge is already known prior to training and what may be retained in the following months between training sessions. Frequent training would help staff feel more competent in performing effective CPR (Geerligs et al, 2018). There are no papers or evidence to suggest that regular or any CPR training is implemented in veterinary hospitals within the UK, this again demonstrates a known knowledge gap. Evaluation of human studies and papers on CPR suggests that CPR training is lacking in veterinary medicine and could impact on patient outcome — more efficient chest compressions and improved manual ventilation rates could affect post CPA survival rates.
The literature suggests that retraining for CPR is best undertaken every 3–6 months, any longer and skills and knowledge retention begin to deteriorate. The RECOVER guidelines (Fletcher, 2012) that have been created to help veterinary practices in CPA events with CPR as well as use ‘PICO’ style questions to understand knowledge gaps around the subject, suggest training and mock-codes every 3–6 months using low-fidelity manikins. Although these manikins can be beneficial for training within veterinary medicine, patient variability needs to be considered, with species and breed hugely varying (Fletcher et al, 2012). Chest compression depth should be a third to a half of the width of the patient's thorax, and this can be difficult to train if appropriate manikins are not available or easily accessible to veterinary staff. Implementing a training protocol into the veterinary profession may prove beneficial following the evidence within the literature in human medicine, training should follow the RECOVER guidelines (Fletcher, 2012). Introducing a new protocol may be met with some resistance, and staff may find it difficult, however a potential improvement in patient outcome should be considered (Geerligs, 2018).