a b s t r a c t

Objective: To assess the differences in the quality and self-perception of CPR performed with foot technique com- pared to the standard technique with the hands in nursing students.

Methods: 65 university nursing students participated in a randomized simulation Crossover design study. The participants randomly performed two CPR tests: CPR by foot and CPR by hands techniques. The compression-

only protocol with a 2-min test was used with the Resusci Anne QCPR(R) manikin and Wireless Skill Reporter(R)

software, both from Laerdal. Results: Participants had lower quality when doing CPR by foot (72%) than when doing standard CPR (91%) (p = 0.006). 95% of the participants indicated standard CPR as the technique of choice, while 92% indicated that they would use CPR by foot if it was not possible to perform standard technique.

Conclusions: CPR quality was lower when performing foot technique, although with positive results. It would be advisable for people with acquired CPR skills to know that they can do foot compressions in situations where they cannot use their hands.

(C) 2021

1. Introduction

Out-of-hospital cardiac arrest (OHCA) is a leading cause of death worldwide and is a major global problem [1]. It is estimated that it af- fects about 700,000 people a year in Europe and North America [2,3]. The use of cardiopulmonary resuscitation (CPR) in the first moments after a OHCA event is vital for the survival prognosis of victims [4]. In order to improve the prognosis for survival and recovery, scientific evi- dence has been sought for decades so as to provide recommendations for the treatment of OHCA [1].

Since the 1970s, evidence has been provided on the use of foot in performing chest compressions as an alternative to the use of hands. This case has been evaluated mainly due to its implementation by peo- ple who are unable to perform quality CPR with because of their partic- ular physical characteristics [5-9]. However, the various Resuscitation boards have never really taken it into account as a recommendation [1]. A person who is trained and skilled at CPR may be in a particular sit- uation in which either he or she cannot perform chest compressions as recommended by ERC guidelines [1]. For example, this may be due to a

* Corresponding author at: Faculty of Education and Sports Sciences of Pontevedra, University of Vigo, Campus A Xunqueira s/n, CP: 36005 Pontevedra, Spain.

E-mail address: [email protected] (M. Otero-Agra).

situation like having arm injuries. The ERC does not refer to this scenario in its “Special circumstances” section and therefore does not provide any recommendations in such cases [10].

Therefore, the objective of this study was to evaluate the differences in the quality and self-perception of an alternative CPR technique (by foot) when compared to the recommended technique (by hand).

1. Methods
   1. Sample

A total of 65 nursing students from the University of Vigo (Spain) participated in the study. In order to determine the sample size, an esti- mation analysis was carried out based on a minimum assumption with the following characteristics: effect size (ES) = 0.5 / probability of alpha error = 0.05 / statistical power = 0.95. The corresponding sample size given by the data provided by the G*Power 3.1.9.2 software was N = 47. After this analysis and having conducted convenience sampling with student volunteers, a calculation of the minimum effect of the differ- ences was made with the sample size of N = 65 and the same values of probability of alpha error and power, resulting in ES = 0.42. The in- clusion criteria in the study were: be a student nurse with CPR skills ac- quired in specific training and participate voluntarily. The exclusion

https://doi.org/10.1016/j.ajem.2020.12.086

0735-6757/(C) 2021

criteria were to have some type of physical limitation for performing the CPR. All participants signed the informed consent form and no participant was excluded. In addition, the data was anonymized. The research was approved by the Ethics Committee of the Univer- sity Nursing School at the University of Vigo and the ethical princi- ples of the Declaration of Helsinki were also respected. 83% of the participants were women (N = 54).

• 1. Design

A randomized crossover simulation study was conducted (Fig. 1). Firstly, the authors of the study (N = 5) carried out a pilot test in order to evaluate the compression technique of the foot which would be identified as an “experimental test”. After several checks using differ- ent techniques, it was decided to use the one indicated by Bilfield et al.

[5] and modifying it in order to apply it to footwear (for more similarity to a real situation). The compressions with the foot were made by supporting the heel and the foot used to do the test was chosen by the participants”. For the study, the 65 participants previously underwent a 5-h theoretical and practical CPR training session. Before the test, all the participants had the opportunity to carry out a familiarization with the two techniques (experimental test: CPR by foot / control test: CPR by hand): 1 min of CPR compressions only with each technique

on the Little Anne QCPR(R) manikin with visual feedback provided by In-

structor App(R). After a minimum of two minutes rest, the CPR evaluation

test begins. The Research Randomizer software (www.randomizer.org) was used to randomize the order of the two tests [11]. Both the duration of each test and the minimum rest time between tests, was 2 min. The

Resusci Anne QCPR(R) dummy (Laerdal, Norway) and the Wireless Skill

Reporter(R) software (Laerdal, Norway), programmed according to cur- rent ERC recommendations, were used for data collection [1].

• 1. Variables

The continuous variables of the CPR were as follows: CPR quality, in percentage terms; total compressions; mean rate, in compressions/min; mean depth, in millimeters (mm); compression time, compressions with correct rate, compressions with correct depth, compressions with correct release, and compressions with correct compression point, in percentage terms.

The number of participants who achieved values >= 70% CPR quality as a categorical variable was calculated. 70% CPR quality is indicated by Perkins et al. as the gold standard in CPR [12]. The participants’ per- ception variables (perception of CPR quality, perception of injury risk to the victim and fatigue with the technique, all in percentage terms with values between 0 and 100), were collected after completing each test with a visual analog scale [13]. The number of participants who in- dicated values >= 70% in the perception of their CPR quality as a categor- ical variable was calculated. At the end of the tests, the participants were asked about the technique of choice in a hypothetical real case and about their consideration of performing CPR with their foot as an alter- native to hands in the case of being unable to perform CPR with the hands.

• 1. Statistical analysis

The statistical analysis was performed with IBM SPSS Statistics soft- ware version 20 for Windows (SPSS, Inc., Armonk, NY, USA). Categorical

Fig. 1. Design study flow chart.

variables were described through absolute and relative frequencies. Continuous variables were described through central tendency (me- dian) and dispersion (IQR) measures. In the text the variables were de- scribed as follows: median (Q1 - Q3).

To make the comparisons between the two tests, the Chi Square test was used in the categorical variables and the ES of the significant com- parisons was calculated with Cramer’s V test. For the continuous vari- ables, after checking the normality of the distributions and verifying that all the comparisons did not meet these criteria with the Kolmogorov-Smirnov test, the Wilcoxon rank sum test was used. The Rosenthal test was used for the calculation of the ES. In all comparisons a 95% Confidence level was established.

1. Results

The results corresponding to the demographic characteristics of the participants are shown in Table 1. The median age was 21 years (19-23). The median height was 166 cm (162-172) and the median weight was 64 kg (58-78).

The results (see Fig. 2) of the CPR continuous variables are shown in Table 2 and Fig. 2. The CPR quality of the experimental test (72%) presented significantly lower values than the control test (91%) with a value of p =

0.006. In the variables of total compressions (experimental test: 210

compressions vs. control test: 225 compressions; p < 0.001) and mean rate (experimental test: 108 compressions/min vs. control test: 114 com- pressions/min p < 0.001) significantly lower values are also seen in the ex- perimental test. The same is true for compressions with correct rate (experimental test: 58% vs. control test: 93%; p < 0.001), compressions with correct depth (experimental test: 45% vs. control test: 60%; p = 0.010), compressions with correct release (experimental test: 76% vs con- trol test: 100%; p < 0.001) and compressions with correct compression point (experimental test: 100% vs control test: 100%; p = 0.002).

However, the mean depth showed no difference between the exper- imental test (50 mm) and the control test (51 mm). Neither was there any difference in the compression time of the test, since in both tests compressions were carried out during the two minutes.

In relation to the participants’ perception variables (Fig. 2), the per- ception of the CPR quality presented by the experimental test (47%) showed significantly lower values than the control test (70%) (p < 0.001). The perception of injury risk to the victim (experimental test: 69% vs. control test: 45%; p < 0.001) and the perception of fatigue (experimental test: 72% vs. control test: 59%; p = 0.002) were signifi- cantly higher in the experimental test compared to the control test.

The results of the categorical variables are shown in Table 3. The pro- portion of students who obtained a CPR quality value higher than 70% in the experimental test (55%) was lower than in the control test (69%),

Table 1

Demographic characteristics.

N = 65	Median	IQR
Age (years)	21	19
		23
Height (cm)	166	162
		172
Weight (kg)	64	58
		78

BMI (kg/m²) 23 21

25

Absolute freq. Relative freq.

Gender Women 54 83%

Men 11 17%

IQR: Interquartile range. Freq: Frequency.

BMI: Body Mass Index.

although it did not show significant differences (p = 0.10). On the other hand, the proportion of students who perceived having per- formed CPR with a quality superior to 70% was significantly lower in the experimental test (12%) than in the control test (59%) (p < 0.001). When faced with a case of cardiac arrest in the technique of choice, 95% of the participants indicated that they would choose hand CPR. When asked if they would consider using the foot CPR technique in the event of an inability to perform hand CPR, 92% of the participants re-

plied positively (see Fig. 2).

1. Discussion

The aim of this study was to evaluate the differences in quality and self-perception of an alternative CPR technique, performed by foot, when compared to the standard technique, performed by hand. Fur- thermore, the opinion of the participants with respect to the main method of choice has been evaluated, as well as the option of carrying out this modality as an alternative in an exceptional situation in which the standard technique cannot be used.

When using high-fidelity manikins, Perkins et al. arbitrarily pro- posed the value of 70% as the optimal quality cut-off point when performing CPR [12]. This study is, to our knowledge, the first to evalu- ate the overall Quality of CPR using the foot technique [1]. Both tests pre- sented higher values, with the standard hand technique being superior to the experimental foot technique. The data strengthens the value of the standard hand technique as the most efficient technique for performing CPR, and only considers the evaluation of the experimental foot technique if it is not possible to use the hand method.

No differences have been observed when evaluating the compres- sion time percentage, with both techniques assuring the massage unin- terruptedly from the outset. This is a sign of quality, since the rapid activation of the Chain of survival and the early start of chest compres- sions play a vital role in the chances of survival of an OHCA victim [4]. In its recommendations, the ERC also highlights the importance of avoiding interruptions in chest compressions after the start of CPR [1].

To achieve the recommended depth, considerable force must be exerted on the sternum with each compression [14,15]. Previous studies of compressions by foot have found diverse results in relation to depth [5-7,16]. In our study, the mean depth showed no difference be- tween the two techniques, thus fulfilling the recommendations of the ERC [1]. On the other hand, the percentage of compressions with correct depth was lower when using the experimental technique by foot com- pared to by hand. This suggests that the standard technique would be more positive in optimizing the recommended depth when performing CPR. The use of the experimental foot technique would favor a less deep CPR.

To our knowledge, none of the studies that have evaluated the foot technique have taken into account the compression point according to current recommendations. Some evidence advises focusing compres- sions on the left side of the sternum, over the area in which the apex of the heart is located where the left ventricular inflow tract (LVIT) is, because this would maximize the CPR effectiveness [17-19]. In this study, the correct compression point was limited by the manikin used. In this case, the foot CPR technique has registered positive values, al- though lower than the hand CPR technique. On the other hand, the re- sults observed in the study by Kherbeche et al. refer, both in the correct rhythm and in the correct release, significantly worse values in the group that did CPR by foot [7]. This is in accordance with the results evaluated in this study, in which the standard technique obtained higher quality results than the experimental technique.

Several studies have evaluated the use of the foot as a possible rec- ommendation for light or fatigued rescuers [5-9]. In relation to CPR, one of the goals would be to expand training amongst citizens. Conducting different training on people who are capable of performing the standard technique could be counterproductive to this goal. Another study has evaluated the performance of CPR by using a hoist and has

Fig. 2. Participants’ perception and choice of technique variables.

shown promising results against not using the hoist and doing the CPR by hand [16]. However, in addition to the fact that specific training in this new technique would be required, this would depend on the avail- ability of a lift.

Finally, the study by Trenkamp et al. showed better tolerance and re- sistance when using the foot technique amongst people who have prob- lems performing CPR with the standard technique (i.e. arm problems, hand flexibility, pain, etc.) [20]. In this case, it could be interesting to

implement different training for people with these characteristics. The present study aims to provide evidence for the performance of the tech- nique using the foot by people with previous training in CPR in exceptional situations in which the standard technique by hand is not possible (i.e. injuries in the upper limbs, scenarios with lack of space, etc.). This could be evaluated as a technique with considerable quality for performing compressions in a particular circumstance in which the rescuer cannot perform CPR by hand.

Table 2

CPR continuous variables.

N = 65 Experimental test (CPR by foot) Control test (CPR by hands) Wilcoxon Signed Rank Test

	Median	IQR		Median	IQR	(Rosenthal test)
CPR quality (%)	72	54		91	62	p = 0.006 (0.24)
		84			97
Total C	210	192		225	215	p < 0.001 (0.37)
		228			235
Compression time (%)	100	100		100	100	p = 0.84
		100			100
Mean depth (mm)	50	46		51	47	p = 0.51
		53			55
C with correct depth (%)	45	23		60	28	p = 0.010 (0.23)
		55			76
C with correct compression	100	89		100	100	p = 0.002 (0.27)
point (%)		100			100
Mean rate (C/min)	108	99		114	107	p < 0.001 (0.36)
		116			119
C with correct rate (%)	58	15		93	60	p < 0.001 (0.32)
		83			99
C with correct release (%)	76	50		100	87	p < 0.001 (0.39)
		87			100
Significance level: p = 0.05. IQR: Interquartile range. C: Compressions.

Table 3

Categorical variables.

N = 65 Experimental test (CPR by foot) Control test (CPR by hands) Chi Square test (Cramer’s V test)

	Absolute freq.	Relative freq.		Absolute freq.	Relative freq.
CPR quality >= 70%	36	55%		45	69%	p = 0.10
Perception of CPR quality >= 70%	8	12%		38	59%	p < 0.001 (0.48)

Significance level: p = 0.05. Freq: Frequency.

Perceptions are not always linked to reality, but should be taken into account when making assessments [21]. In this case, the participants’ perception is that the standard technique by hand implies a higher qual- ity in the performance of compressions, as well as a lower risk of injury to the victim and less fatigue than the CPR technique by foot.

CPR is an activity that leads to considerable muscle fatigue [22,23]. Participants in this study reported that the technique by foot leads to greater perceived fatigue than the standard technique. Most partici- pants rated hand CPR as the technique of choice in the event of cardiac arrest. On the other hand, they have also assessed foot CPR as an alter- native in a situation in which the standard technique could not be per- formed. The results of the perception variables suggest that the foot technique has disadvantages compared to the hand technique, although it should be taken into account in exceptional situations.

• 1. Practical applications

The results of this study indicate that the quality of the experimental technique by foot is relatively good, although it is below standard. How- ever, the implementation of training with Alternative techniques that can replace CPR by hand could be counterproductive in expanding skills. By observing these results, along with previous evidence, training in foot CPR should be encouraged amongst people who do not have a real possibility of performing compressions according to current recom- mendations (amputations of upper limbs, inability to bend over, etc.).

Section 4 of the ERC guidelines (cardiac arrest in exceptional circum- stances) deals with special etiologies, scenarios and victims [10]. These do not mention the circumstances of the rescuer. The message that peo- ple with CPR training are capable of performing foot compressions of considerable quality in an exceptional circumstance in which the stan- dard technique cannot be performed should be encouraged. In this way, it is possible to prevent situations in which a person does not per- form CPR if he or she is not capable of using the conventional technique.

• 1. Limitations

This study presents a simulation design with manikin. A real situa- tion generates stressful stimuli which are impossible to simulate in a de- sign with manikin. The results observed may not coincide with those of a real situation. The participants had CPR training using the standard technique whose contents were much more comprehensive than the fa- miliarization used for the foot technique. The correct compression point of the manikin may not be the one that produces the greatest efficiency in performing CPR. Perception through visual analog scale does not present the reliability to assess fatigue that other more accurate tech- niques present. The perception of a victim’s injury risk is also a variable that has limitations. No other form of greater reliability has been found to assess this assumption in manikin.

1. Conclusions

This study provides evidence for the use of chest compressions car- ried out by foot compared to the recommended hand technique amongst nursing students with standard CPR skills. In this case, they are able to do quality chest compressions with their feet with little or

no prior training. However, when using the foot, the CPR quality is lower while the perception of fatigue and injury risk to the victim is higher. Participants have rated hand CPR as the primary technique of choice, using the foot only in exceptional circumstances. It would be ad- visable for people who have CPR skills to perform chest compressions by foot only in cases in which current recommendations cannot be carried out. The implementation of this technique as a real alternative to stan- dard CPR could be counterproductive but it may be valuable as an op- tion for people who have no possibility of doing chest compressions with their hands.

This research did not receive any specific grant from funding agen- cies in the public, commercial, or not-for-profit sectors.

Funding declaration

None.

Credit authorship contribution statement

Martin Otero-Agra: Conceptualization, Formal analysis, Methodol- ogy, Writing - original draft. Noemi Santiago-Urgal: Data curation, In- vestigation, Resources, Writing - original draft. Maria Teresa Hermo- Gonzalo: Conceptualization, Methodology, Supervision, Writing - review & editing. Maria Fernandez-Mendez: Investigation, Project administra- tion, Writing - review & editing. Felipe Fernandez-Mendez: Methodol- ogy, Project administration, Supervision, Writing - review & editing.

Declaration of Competing Interest

None.

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