Teaching Basic Life Support to schoolchildren: quasi-experimental study

Objective: to evaluate the knowledge of basic education students before and after educational intervention on Basic Life Support in a situation of adult cardiorespiratory arrest. Method: quasi-experimental study conducted with 335 students from three elementary schools. Data was collected using an instrument that captured sociodemographic data and knowledge about Basic Life Support. Subsequently, they were analyzed by descriptive and analytical statistics. Results: students’ knowledge in the post-test (p <0.05) was significantly higher than in the pre-test. The average of the pre-test scores was 4.12 ± 1.7 and, in the post-test it was 6.53 ± 1.9 (p = 0.00). Conclusion: the results demonstrated effectiveness of the intervention with the expansion of knowledge about Basic Life Support in cardiorespiratory arrest. The results reinforce the importance of Nursing in health education actions in elementary schools.


Introduction
Basic Life Support (BLS) conducts are defined as initial actions offered by trained people (1) to victims of sudden illness, accidents and/or at imminent risk of death. Most of these measures are carried out at the event site until more complex procedures are implemented by health professionals (1)(2)(3) .
Studies (1,4) pointed out that the main cause of prehospital death is the lack of care, followed by inadequate assistance. In the case of Cardiorespiratory Arrest (CRA), if the resuscitation maneuver is performed within the first minute, the chances of success are up to 98%. From the fifth minute on, the chances drop to 25% and survival rates drop to 1%, if the resuscitation maneuver is performed after ten minutes.
In this sense, the actions provided by trained people are crucial for better prognosis and survival in situations such as hemorrhages, fainting, choking and CRA that occur, in general, outside health institutions (3) . Studies have highlighted that the CRA resuscitation maneuver, initiated by trained people until the arrival of emergency services professionals, is associated with a survival rate up to three times higher when compared to victims in CRA who did not receive assistance (4)(5)(6) .
Cardiovascular diseases are responsible for approximately 15.2 million deaths per year worldwide (7)(8) .
Among the countries with the highest mortality rate, Brazil occupies the tenth position, representing 27.7% of deaths, mostly preventable (7) , due to heart disease. These data reinforce the need for training to the general population, with the school being an environment conducive to teaching and spreading knowledge about management in situations that require first aid, since children and adolescents are always willing to acquire new knowledge (2) .
In the basic education environment, some research has shown that the knowledge and skills of teachers and students in caring for victims in situations of CRA can be improved after educational intervention (4,9) . When the offer of educational activities on CRA is regular, the chances of promptness and effectiveness in attendance are greater, considering that knowledge and skills may be reduced over time (2) . Therefore, the nurse through the guidelines of the Health at School Program (HSP), figures as one of the main mediators between education and health, being able to act, strategically, in the provision of educational activities in first aid (10) .
A study highlighted that, among health professionals, nurses are effective in activities with basic education, as they have been protagonists in the connection between school and health, which enables the acquisition of skills and the establishment of bonds (11) . In addition, this professional has managed to extrapolate technical rationality, from a dialogical and reflective practice, in order to enable greater involvement of those who learn (12) .
Through the literature, it is evident that, in educational activities aimed at teaching maneuvers in situations of CRA, the nurse instructor must use resources that stimulate the cognitive and metacognitive skills of the apprentice in the field of decision making (9,(13)(14) . Thus, in addition to theoretical information, it is important for nurses to stimulate knowledge and skills through practical pedagogical strategies, with repetition actions, so that the student stops being a mere spectator and starts to act safely (9) .
In this sense, the objective of the study was to evaluate the knowledge of basic education students before and after educational intervention on Basic Life Support (BLS) in a situation of adult CRA.

Method
This is a quasi-experimental study, of the before and after type, non-randomized, in which the and practical BLS activities (4) . As exclusion criteria, we considered those who were away from school activities due to sick leave at the time of data collection.
For the sample calculation, the following formula was "n" is the calculated sample; "N" is the population; "Z", the standardized normal variable associated with the confidence level; "P", the true probability of the event and "e", the sampling error, using a sampling error of 5% and a 95% confidence level. A sample size of 241 students was obtained. However, the authors preferred to exceed the minimum sample size, 335 students taking part in the investigation.
The selection was made out of convenience according to the students' availability to participate in the study. Randomization was not performed because it was a study before and after (of the intervention). It is worth mentioning that, in addition to the 335 students, seven others participated in educational activities, but not in the research, either by choice or by non-consent of those responsible.
Data was collected using an instrument previously developed and validated in Brazil (14)  according to the American Heart Association protocol (8,15) .
At the third station, the group, with the help of one of the tutors, performed the practical approach, providing care to a likely victim in CRA. For this, three simulation mannequins were used. In a fourth season, students individually performed the maneuver on a mannequin and, at the end, received feedback on their action, with the possibility of repeating the procedure.
The post-test was performed in the fifth season.
In a reserved environment, as in the first season, the  did not know what to do, because they did not feel safe.
Another 123 (36.7%) performed some action that they considered correct, such as checking a pulse, sitting down or giving water to the person, and then took the victim to the hospital. Table 1 shows, comparatively, the frequency and significance of students' responses in the pre and posttest on BLS to a victim in CRA.
From the data presented in Table 1, it is possible to infer that the students' knowledge in the post-test (p <0.05) was significantly higher than in the pre-test.
The average of the pre-test scores was 4.12 ± 1.7 and, in the post-test, the average was 6.53 ± 1.9 (p= 0.00).
It can be confirmed, by exploring the data in Figure 1, that, in all questions, the rate of correct answers after the theoretical-practical exposure was higher than the previous one.  Although there is no consensus in the literature on the appropriate time to learn about this topic, some studies highlight that the teaching of FA has happened late, including to undergraduate nursing students (4,(23)(24)(25) .
Studies (20-23) evidenced, through specific tests, that there is a significant increase in safety and willingness to provide BLS assistance in situations of CRA after theoreticalpractical training of students or the general population.
In a research (26) held in Saudi Arabia, with a population of 508 high school students, low prior knowledge was identified, in addition to low security and willingness to assist in CRA. However, after the theoretical-practical educational intervention, there was a significant improvement in knowledge and skills. These data corroborate the findings of this study, in which there was a significant variation between the pre and immediate post-test, demonstrating an improvement in the knowledge acquired.
It should be noted, however, that there are evidences that the retention of knowledge and skills in cardiopulmonary resuscitation maneuvers declines over time and updates are recommended (5,8,21) . Nursing

Discussion
The school is understood as a multidimensional space for sharing relationships, culture, stories and knowledge.