A randomized comparison trial of two and four-step approaches to teaching Cardio-Pulmonary Reanimation.

BACKGROUND AND AIM OF THE WORK: The treatment of cardiac arrest in an extra-hospital environment improves with the increase in the number of people able to establish an early Cardio-Pulmonary Reanimation (CPR). The main aim of the study was to assess the validity of the two-step method in case of prolonged CPR.
METHODS: A randomized comparison study was conducted in the University Nursing School of a Northern Italian town, during the 2015/16 academic year, among 60 students, to teach them CPR techniques, through two different teaching methods (4-step and the 2-step of CPR training). The effectiveness of the maneuvers performed on mannequins equipped with skill-meter was verified.
RESULTS: Our study did not highlight any significant difference between the two methods of CPR training. The comparison between the two methods regarding their efficacy in practical teaching of CPR, highlighted by this study, proved the validity of both the 4-minute continuous method (1st method) and the 30:2 method (2nd method).
CONCLUSIONS: The results of the study showed no differences between the 2-step and the 4-step methods, in the effectiveness of cardiac massage. The correct execution of chest compressions during a CPR is the key to increase the patient's chances of rescue. Research has shown that any interruption in the execution of chest compressions, leads to a progressive reduction of the effectiveness of cardiac massage, with negative consequences on the prognosis of the patient undergoing at CPR.

RCT Entities:   Population Interventions Outcomes

Background

Extra-hospital cardiac arrest is still a serious public health problem. The metaphor of the “Chain of Survival”, coined by the American Heart Association (AHA) and universally adopted, identifies the basic phases for successfully resuscitating victims of cardiac arrest (1). Identifying cardiac arrest can be difficult. Both bystanders and those who manage the emergency calls must immediately recognize cardiac arrest in order to promptly activate the survival chain (2). The key symptoms for recognizing a cardiac arrest are: the victim is unresponsive, does not breathe normally and does not show any signs of circulation (3, 4).

Unfortunately, only at times bystanders start Cardio-Pulmonary Reanimation (CPR) on their own in case of cardiac arrest. It has been demonstrated that CPR telephonically guided by the emergency operative center increases the survival rate (2), reduces the time that elapses between cardiac arrest and the beginning of the first chest compression (5, 6), increases the number of chest compressions performed (7) and improves the prognosis of victims of extra-hospital cardiac arrest (8-10). The emergency center operators should provide instructions to perform CPR with chest compressions only if the cardiac arrest victim is an adult. Immediate CPR can double or quadruple survival after cardiac arrest (11, 12).

The European Resuscitation Council (ERC) supports the recommendations of the International Liaison Committee on Resuscitation (ILCOR), according to which a chest compression with a depth of about 5 cm but no more than 6 cm, is reasonable in the average adult (13). A frequency of at least 100 compressions per minute, without exceeding 120 compressions per minute, with the fewest interruptions possible (14), and with equal times for the compressions and release phases is optimum (15, 16). Teaching CPR is fundamental for training and the most effective method for training it should be identified (17). A model that has been increasingly affirmed in medical and university training since 2000 is Peyton’s Four Step Approach, a 4-step method of instruction, normally used in the training courses of the European Society of Cardiology (ESC)(18).

The 4-step teaching method developed by Peyton provides the following sequence:

- phase 1: technique performed by the instructor in real time and in silence;

- phase 2: CPR is repeated and commented by instructor with explanations of reasons for each action;

- phase 3: the demonstration is repeated by the instructor under the direction of one of the learners;

- phase 4: the execution of the phase is repeated by a learner.

Although this approach is theoretically very convincing, as a cognitive procedural model there is no evidence that it leads to superior results in terms of learning compared to other teaching methods (19). Several studies compared the effectiveness of the 4-step method with other teaching models. Greif’s randomized controlled trial compared the Peyton 4-step teaching method with the traditional “see one, do one” method to teach a specific technical skill such as cricothyroidotomy (20). Orde’s study compared the 4-step teaching method with the traditional 2-step method for inserting the laryngeal mask (21). Orde’s training method uses steps 2 and 4 of the Peyton 4-step method. The study did not show a statistically significant difference between the 2- and 4-step methods either in terms of acquiring the skill or remembering it over time.

Aim

The main aim of the study was to assess the validity of the two-step method in case of prolonged CPR. Secondary aims were:

- to verify if periodic two-second interruptions every thirty chest compressions allow the rescuer to maintain an effective cardiac massage for a longer time, regardless of whether the ventilations are performed or not;

- to verify if a feedback system on the effectiveness of chest compressions (Skill-meter®) has a positive influence on massage efficacy.

Method

Study design and participants

This randomized comparison trial was conducted in the University Nursing School of a Northern Italian town, during the 2015/16 academic year. Our convenience sample consisted of 60 nursing students: 25 in the first year and 35 in the second year of Nursing course. The students of our sample had never performed CPR.

The sample was randomly divided into two numerically homogeneous groups of thirty students: the experimental and the control group. For allocation of the participants, a computer-generated list of random numbers was used. The two initial groups were subsequently divided into three subgroups composed of 10 students each in order to make teaching easier by reducing the ratio of instructor: students to 1:10.

1st Phase of the study

Before starting the experiment, the 8 CPR instructors were divided into 3 randomized instructor groups: three instructors composed the experimental group aimed at teaching only 2 of the 4 CPR steps described by Peyton, the other three instructors composed the control group to teach the traditional four-step CPR method and the last two instructors composed the evaluation group with the task of evaluating all students’ performance (18). The three groups were double-blinded since the instructors of each group did not know the teaching methodology of the other groups. Moreover, instructors and students were not allowed to attend the other groups’ training and performance.

Before the beginning of the training, each instructor was asked to simulate his/her activities to other instructors in order to ensure that performances were homogeneous. Eight work stations were created, six for student training of and two for instructors’ evaluation. All settings were equipped with ResusciAnne® manikin with Skill-meter®, self-expanding balloon with a medium-sized mask. All the equipment, manufactured by the same company, presented the same technical characteristics.

The research protocol provided for the following proceduresfor each group:

- 15 minutes of training for cardiac massage and ventilation with ambu bag;

- access of three students maximum at a time to each workstation.

After completing the training, the students were randomly sent to the two evaluation stations, where their 2-minute CPR performances were assessed by the two instructors (Figure 1).

Figure 1.

1nd Phase of the study

2nd Phase of the study

After completing the first phase of the study, the two training methods were compared to evaluate the better one for carrying out the External Cardiac Massage (ECM). Method 1 provided the execution of 4 minutes of uninterrupted ECM either with or without the aid of an evaluation tool during practice. Method 2 provided the execution of ECM for 4 minutes with a pause of 2 seconds (theoretical time for the ventilations) every 30 compressions. In this case also the experiment took place either with or without the aid of an evaluation tool. The 8 CPR instructors were randomly divided into four groups (two groups per each method) and the 60 students were numerically homogeneously inserted into the four groups (15 students per group). Two work stations were assigned to each group. The students assigned to the two groups of Method 1 were asked to practice ECM by checking the Skill-meter® for 1 minute; after this, one group continued to practice the cardiac massage with only the aid of a metronome, whereas the other group practiced ECM for 4 minutes supported by both metronome sound and Skill-meter® monitor.

The students inserted in the two groups of Method 2 were asked to practice ECM by checking the Skill-meter® for 1 minute; after this, one group continued to practice the cardiac massage with the aid of only a metronome, whereas the other group practiced ECM for 4 minutes supported by both metronome sound and Skill-meter® monitor. For both training methods, each student was given 5 minutes of time (Figure 2).

Figure 2.

2st Phase of the study

Data from the 1st and 2nd phases of the study were collected on two electronic boards. For each student, we collected personal data, height, weight and his/her performance of ECM (number of massages with insufficient force on the chest of the manikin, the number of massages with excessive force exerted and the correct ECMs) and ventilation (number of insufflation with insufficient pressure to fill the lungs, number of insufflation with excessive pressure and number of correct insufflations).

Ethical considerations

All students enrolled gave us their informed written consent for participation in this study, following our explanation of its purpose and design. Participants’ anonymity and confidentiality were assured and their decision regarding participation in this study was respected. The study was authorized by the Director of the Nursing Degree Programme.

Statistical analyses

Descriptive statistical analyses were performed: means and standard deviations for continuous data, and percentages for categorical data. t-test and ANOVA were applied to identify significant differences among continuous data. Categorical variables were calculated through the contingency tables and the differences were detected through the Chi-square. Multiple comparisons were performed using Tukey’s Honestly Significant Difference (HSD). We considered statistical significance to have been attained if p <.05. The statistical analysis was performed using the SPSS software.

Results

Sixty students were enrolled in the study: 10 males (16.7%) and 50 females (83.3%). The mean age of our sample was 22.03 years on average (SD=4.403). Regarding the physical characteristics of the students (Table 1), divided by gender, significant differences were found both in weight (p=.0001) and height (p=.0001), as highlighted by another study (21).

Table 1.

Constitutional variables of our sample

In our sample, the efficacy in performing CPR was not influenced by gender, weight or height of students. Regarding the two methods of CPR, the t-test did not show any significant difference (p=.885), although the number of effective chest compressions was higher in the 2-step method (M=75.24, SD=33.56) than in the 4-step method (M=73.30, SD=32.03) (Table 2).

Table 2.

Comparison of chest compression and ventilation effectiveness in the 2 and 4 step methods

In the second experiment, the number of chest compressions statistically significantly differed between the two methods (t=2.936, p=.005). In fact, the simulator calculation of the average of the total chest compressions performed, demonstrated that, with the 1st method, the students performed an average of 409.96 compressions (SD=28.90), while with the 2nd method, the average number of compressions was 386.28 (SD=33.01).

Regarding the efficacy of the chest compressions, there were no differences between the 1st teaching method and the 2nd one (Table 3). However, 4-minute uninterrupted massage for 4 minutes (Method 1) produced better results: effective massages were 243 on average (SD=115.93), which corresponded to 59.3% of the average total compressions performed with the 1st method, against 203.19 massages on average (SD=128.78) of the ECM followed by interruption (30:2), method 2, which instead corresponded to 52.3% of all massages performed with the 2nd method.

Table 3.

Comparison of the chest compression effectiveness in the 2 and 4 step methods

Regarding the use of the skill-meter, group 2 obtained the highest number of effective chest compressions (306.60±86.83, p=<.0001); it practiced the massage in 4 minutes without interruption with skill-meter support, reporting a percentage of 74.8% correct compressions; group 4 follows, with 66.8% correct massages (257.29±110.55) (Figure 3).

Figure 3.

Effectiveness of chest compressions in the two training methods, with or without use of the skill-meter

However, the multiple comparison showed significant differences between group 2 and group 1 (MD=-134.979, p=.012) as well as between group 2 and group 3 (MD=-147.533, p=.003), but not between group 1 and group 4 (MD=98.534, p=.095).

Discussion and conclusions

Our study did not highlight any significant difference between the 4-step and the 2-step methods of CPR training. Therefore, the results obtained from this research suggest the validity of the Orde 2-step method (22) as well as the Peyton 4-step method. This result was further confirmed by the comparison between the two methods regarding the efficacy of chest compressions and ventilations and errors recorded by the simulators’ skill-meters. Differently from a recent study (21), the personal and physical characteristics of our students did not affect their training performances in CPR.

Furthermore, the 2-step method permitted students to have more time to perform the practical maneuvers through the simulator, whereas the instructor had more time to do corrective interventions. For this reason, the 2-step method could be useful for health care workers and non-professionals who need practical training in CPR maneuvers and airway management (22). Moreover, we suggest that the choice between the Peyton and Orde method could depend on the organizational peculiarities of health setting or training course that promotes training.

The comparison between the two methods regarding their efficacy in practical teaching of CPR, highlighted by this study, proved the validity of both the 4-minute continuous method (1st method) and the 30:2 method (2nd method).

Finally, we suggest that the choice between the 1st or 2nd method could be inferred from the results obtained by the four groups of our students who used the Skill-meter® during CPR. In fact, our results highlighted the effectiveness of both methods in groups 2 and 4, where students used the Skill-meter®. This result indirectly suggests that the correct choice of teaching method depends on the availability of simulator equipment and not on the typology of method: for health settings or institutions with low technology instruments, which do not permit the evaluation of students’ performances during chest compressions, the method which involves 4 uninterrupted minutes of massage could be preferred, whereas, the availability of medium-high technology simulators, could permit the use of the traditional 30:2 method.

We conclude by highlighting that both clinical learning and competency development are essential parts of nursing teaching (23) and realistic simulation can be an effective training method, especially if it is supported by the presence of trained instructors (24, 25).

The main limit of the study was represented by the small size of our sample, not homogenous for gender but only for age. Furthermore, the skill retention after a period of time was not verified due to the difficulty to collect the same sample in a follow-up (most of students subsequently participated in complete CPR course, or they began working, or transferred to other locations).

To confirm our results, further studies with bigger sample, including subjects with different professional and personal characteristics, are necessary.