A comparison of the effect of two methods of positioning the hands during basic and advanced cardiovascular life support on the chest compression depth in adults

Introduction: There is no agreement on how the hands are positioned in cardiopulmonary resuscitation (CPR). In this study, the effects of two methods of positioning the hands during basic and advanced cardiovascular life support on the chest compression depth are compared. Methods: In this observational simulation, the samples included 62 nursing students and emergency medicine students trained in CPR. Each student performed two interventions in both basic and advanced situations on manikins and two positions of dominant hand on non-dominant hand, and vice versa, within four weeks. At each compression, the chest compression depth was numerically expressed in centimeter. Each student was assessed individually and without feedback. Results: The highest mean chest compression depth was related to Basic Cardiovascular Life Support (BCLS) and the position of the dominant hand on non-dominant hand (5.50 ± 0.6) and (P = 0.04). There was no statistically significant difference in the basic and advanced regression variables in men and women except in the case of Advanced Cardiovascular Life Support (ACLS) with dominant hand on non-dominant hand (P = 0.018). There was no significant difference in mean chest compression during basic and advanced cardiovascular life support in left- and right-handed individuals (P = 0.09). Conclusion: When the dominant hand is on the non-dominant hand, more pressure with greater depth is applied.


Introduction
Timely performance of a cardiopulmonary resuscitation (CPR) rescuer is one of the key factors in increasing the survival rate in victims of OHCA, but nevertheless only a small number of victims of OHCA are potentially saved by the CPR rescuer. In this regard, CPR training may help improve the outcomes of cardiac arrest. 1 Over the past decade, devices have been developed that offer audio and video feedback during compression of the chest to improve the quality of the CPR. 2,3 However, whether these methods and devices increase chest compression efficiency is controversial. 4,5 An alternative approach to improve the performance of rescuer was placing the dominant hand against the chest during compression. 6 In this regard, Nikandish et al 7 reported that the quality of chest compression within 5 minutes was in accordance with previous guidelines for chest compression CPR independent of the hand in contact with the chest. Kundra et al 8 also reported that compression of the chest was done with fewer mistakes when the dominant hand contacted the chest. In the protocol proposed by the American Heart Association, the fact that the dominant hand must be positioned on the non-dominant hand for compression or vice versa is not mentioned. It seems that the chest compression depth is different in the two cases. In this study, the effects of two methods of positioning the hands during basic and advanced cardiovascular life support on the chest compression depth are compared.

Materials and Methods
In this single-blind interventional study, the statistical population included 62 nursing students and emergency medicine students, who entered the study through census. The inclusion criteria were nursing students of semesters 6 and 8, and emergency medicine students of semester 3 who completed basic and advanced cardiovascular life support training courses. Students' unwillingness to participate in the study or continuing their participation were considered as exclusion criteria. The study environment was Clinical Skills Center at the Faculty of Nursing and Midwifery of Ilam University of Medical Sciences. The study was conducted from November 2017 until April 2018. The students reviewed the basic and advanced cardiovascular life support workshop one week before the intervention for four hours under the supervision of the trainer, and then each student performed four interventions (two interventions in the two basic and advanced situations). In the first intervention, the student was asked to resuscitate the patient on the ground (basic cardiovascular life support) assuming that the patient's airways have been stabilized, while the dominant hand was positioned on the non-dominant hand for chest compression. Each time, only 3 compressions were applied on the chest and at each respiratory cycle, 3 breaths were given. In the second step, the student was asked to resuscitate the patient on the ground (basic cardiovascular life support), while the non-dominant hand was positioned on the dominant hand for chest compression. Each time, 3 compressions were applied on the chest and at each respiratory cycle, 3 breaths were given. In the third step, the student was asked to complete the first and second steps on the manikin (JYCPR-007 Half Body CPR Training Manikin), which was located on the resuscitation bed (advanced cardiovascular life support). Giving breath was measured by manikin but was not recorded. In fact, the purpose of giving breath was conducting a single-blind study. In addition, the students were told that the purpose of the study was to "assess the students' knowledge of cardiopulmonary resuscitation". Since tiredness can affect the chest compression depth, each student gave his/her place to another student after compressing the chest, and did not perform resuscitation until the end of the list. One week after the resuscitation by all students, the second intervention took place from the beginning and in the same order. It should be noted that each student was assigned a number as a code to maintain order. The correctness or incorrectness of the position of the hands was determined by the Manikin. For each compression, the Manikin confirmed the correctness or incorrectness of the compressed location, and the intervention was repeated in the following days if the compression position was not correct. Each student was asked to compress the Manikin chest 3 times with maximum force in each intervention. At each compression, the obtained number was recorded by the researcher. The final number, which indicates the compression force, was the average of these 3 numbers.
In the third and fourth interventions, which took place during the third and fourth weeks after the first intervention, the above interventions were repeated. However, the Manikin was placed on the standard resuscitation bed this time; resuscitation on the bed was considered as Advanced Cardiovascular Life Support (ACLS) and resuscitation on the ground as Basic Cardiovascular Life Support (BCLS). At each compression, the Manikin showed the chest compression force numerically in centimeter. The higher the number, the higher the chest compression force. This number was recorded by the researcher. The student could not see the Manikin display and the record sheet. All students were on the right side of the manikin for chest compression. In fact in this study, no matter what the dominant hand was, the dominant hand of all participants was once considered as the right hand and once the left hand in a crisscross form. Each student was also assessed individually, but they were not provided with any feedback. It should be noted that the correctness of the massage performed by the students is confirmed by manikin and coach. SPSS version 21 was used to analyze the data. The significance level of data was considered to be P<0.05.

Results
Overall, 62 students participated in the study ( Table  1)

Discussion
The results of this single-blind study showed that in basic and advanced cardiovascular life support, the way the hands are positioned and which hand is in contact with the chest affect the depth of chest compression; the depth of chest compression is greater if the non-dominant hand is in contact with the chest. However, the mean depth of chest compression in basic cardiovascular life support was higher than advanced cardiovascular life support. There is no recommendation in this regard in the European (ERC) and American guidelines (AHA), 8,9 11 Differences between the results of this study and other studies may be due to differences in experiences of participants (students in this study, rescuers 7 and anesthesia residents, 10 study method and manikins used in resuscitation: UCC-CPR versus standard chest compression-ventilation CPR 10 and JYCPR-007 Half Body CPR Training Manikin in this study), and the difference in sample size. In this study, there was no statistically significant relationship between the depth of chest compression and the dominant hand. In other words, right-handedness or left-handedness did not affect the depth of chest compression during resuscitation. However, Jo et al 12 suggest that ECC in the group that used dominant hand was significantly faster than the group that used nondominant hand. The contact of the dominant hand with the chest can affect the depth of chest compression.

Limitations
One of the limitations of this study is the use of manikins. Performing CPR by a simulated scenario cannot adequately provide cases of chest compression and physiological differences among victims of cardiac arrest.

Conclusion
The results of this study show that when the dominant hand is on the non-dominant hand, it applies more pressure than when it is positioned in the opposite direction. Simply put, in CPR, which emphasizes the effective chest compression, it is better to put the dominant hand on the non-dominant hand to activate blood circulation efficiently.