Implementation of a Breast Adjunct for CPR Training Manikins Increased Reported Comfort in Performing CPR on Women

Keywords: CPR education, female CPR manikins, out-of-hospital cardiac arrest, bystander CPR

Abstract

Previous studies have shown that women are less likely than men to receive bystander CPR during an out-of-hospital cardiac arrest. One potential contributor to this disparity is the widespread lack of female representation in CPR manikins and CPR instructional materials. For this study, a silicone-based, AED-compatible breast adjunct that attaches anteriorly to non-breasted CPR manikins was produced. This study assessed whether practicing this breast adjunct during CPR training would improve trainee comfort levels in performing CPR on women. Pre- and post-training surveys were administered, with ten questions assessing participant comfort levels in performing CPR on men and women.

We evaluated differences in reported comfort among and between control (trainees who did not practice with the adjunct) and adjunct (trainees who practiced with the adjunct) volunteer rescuers. In the post-class survey comparison, the group that practiced using the female adjunct reported greater comfort in performing CPR on women than the control group, regardless of chest exposure, across all survey questions specific to women (p<0.05). Across these questions, the adjunct group exhibited an overall 1.9 times greater increase in comfort in performing CPR on women after the class than the control group. As such, our preliminary findings provide evidence that breast adjuncts may be used during CPR training to decrease bystander hesitancy in performing CPR on women. Further research on the efficacy of female manikins and breast adjuncts in a randomized controlled setting is warranted to inform CPR education guidelines and address the gender disparity in bystander CPR.

1 Introduction

Administration of high-quality cardiopulmonary resuscitation (CPR) is a critical intervention for a victim experiencing out-of-hospital cardiac arrest (OHCA). Quick action by bystanders can significantly raise the victim’s chances of survival by two- to three-fold.^1–3 With the application of an automated external defibrillator (AED), bystanders can improve a victim’s survival likelihood from 9% without the use of an AED to 24% with the use of an AED.⁴

Since CPR only provides the brain with 30% of its normal blood flow, ineffective bystander CPR can significantly impact survival rates.⁵ Thus, proper CPR training that emphasizes quick action, high-quality compressions, and early defibrillation is key to raising OHCA survival rates.

Despite the established benefits of rapid and proper CPR and AED use, numerous studies show that women are less likely than men to receive bystander CPR.^6–9 Several explanations for this disparity have been proposed. One survey revealed that the reasons for this disparity include fear of causing further injury to a woman, the belief that women may be overreacting and do not truly need CPR, fear of being accused of inappropriately touching the victim, and a reluctance to unclothe a woman in public.¹⁰

Further, one can postulate that a lack of female anatomical representation in CPR training materials and devices might contribute to this disparity. A recent survey of 56 CPR training centers (n=2383 manikins) in North and Latin America found that only 6% of the manikins used were female manikins.¹¹ These devices are not only underused but also understudied with regard to their efficacy. Rigorous studies on the efficacy of female manikins or breast adjuncts implemented in CPR training classes in decreasing bystander CPR hesitancy in women are currently non-existent.

Regarding implementing female anatomical training materials, an important consideration is whether women ultimately have worse OHCA survival outcomes than men. While women are less likely to receive bystander CPR than men, the impact of gender on OHCA survival rates remains unclear. A systematic review of 21 observational studies found that female sex was correlated with higher OHCA mortality.¹² Other studies have similarly found that men have a higher likelihood of survival secondary to an OHCA than women.^6,7,13,14 However, studies also report that women may have similar or better OHCA survival rates than men.^8,9,15,16

Given the gender disparity in bystander CPR, which may affect OHCA survival rates, and the lack of female-anatomy representation in CPR training materials, this study aimed to assess whether the use of a female-anatomy adjunct during CPR training would influence reported comfort levels of trainees in performing CPR on women, and to what extent.

2 Methods

2.1 MassCPR class and breast adjunct design

MassCPR is an annual event hosted by the Massachusetts Institute of Technology (MIT) to certify members of the MIT community in CPR, at no cost to the participants. Participants were recruited from MIT students, faculty, and staff. The event was held in an auditorium on April 30th, 2023, with three classes of 35-45 trainees occurring throughout the day.

Before each class began, trainees were asked to take an optional pre-training survey to assess their comfort in performing CPR on men and women. After an introduction, trainees were invited to approach the CPR training manikins. Five of the thirty-one manikins used had the female anatomical adjunct. The class followed the 2020 American Heart Association (AHA) Heartsaver Adult curriculum, using instructional videos, practice-while-watching, and instructor demonstrations. For each class, five teams of two trainees each practiced with the breast adjunct manikin throughout the entire class, while the remaining students used traditional flat-chested manikins. A student-to-instructor ratio of 6:1 was maintained. Before the final skills assessment, trainees were asked to complete a post-training survey.

The breast adjunct used was constructed from a lifecast silicone mold. It attaches anteriorly to a standard non-breasted manikin, while still allowing the student to observe chest rise and visual feedback lights beneath the manikin. The adjunct, made of special-effects silicone, imitates flesh in texture and color, allowing for AED pads’ adhesion (Figure 2).

2.2 Survey design

Anonymous and voluntary pre- and post-surveys were administered to trainees to assess comfort levels in performing CPR on individuals with and without breasts. Demographic information including pronouns and race were collected in the pre-survey. Trainees were also asked whether they had attended a CPR training prior to the MassCPR training. The remaining questions assessing CPR comfort levels were identical between both pre- and post- surveys.

Trainees were presented with a brief narrative scenario in which they imagined themselves witnessing an individual collapse and administering CPR on this hypothetical victim. They were then asked to answer ten questions regarding their comfort in performing CPR on women vs. men, on a scale of one to ten: 1 (extremely uncomfortable), 5 (neutral comfort) to 10 (extremely comfortable) [Table 1].

2.3 Statistical analysis

Hypothesis tests on the survey results were conducted in RStudio using one-tailed, non-parametric permutation testing. The permutation test is a statistical resampling technique that compares the experimental value (for example, the difference between two means) to many resampled values after randomly swapping data points from the experimental group with data points from the control group.^{17,18(pp202-217)} Based on how the original experimental value compares to resampled values, a p-value may be obtained that describes whether the experimental value is statistically significant, compared to the control group.

This study compared the original experimental value to 100,000 random resampled values. Unlike many conventional statistical methods, including the popular Student’s T-Test, the permutation test makes no assumptions about either group’s parameters or normality, and because respondents were asked to answer the questions in the form of a rating from 1 to 10, there was a possibility for non-normality. A p-value significance threshold of 0.05 was designated for this study. Fisher’s exact tests for the baseline characteristics of the sample, including CPR class history, pronouns, and ethnicity, were performed via STATA/MP 18 (StataCorp, College Station, TX).

3 Results 

3.1 Demographics

To confirm the demographic similarity between control and adjunct groups, Fisher’s Exact tests were conducted. Analysis of baseline characteristics of the CPR class participants showed no significant differences between control and breast adjunct experimental groups regarding experience with prior CPR training, pronouns, and race (Table 2).

3.2 Breast adjunct implementation significantly increased reported comfort levels in performing CPR on women specifically, regardless of chest exposure

For all ten pre-class survey questions, there was no significant difference between the control and adjunct groups (Table 3). An analysis of pre- to post-training changes in comfort levels revealed a statistically significant increase in comfort after the class for both control and adjunct groups, across all ten survey questions (p<0.05), except for the Q3 pre vs. post comparison for the control group (p=0.07), which similarly had a low p-value [these data are not shown in Table 3]. This result shows that participation in the CPR class improved general CPR comfort levels for trainees in both groups, which was expected.

More importantly, however, we found that, in the post-training survey comparison between control and adjunct groups, trainees in the adjunct group reported greater comfort in performing CPR on women, compared to the control group. This increase in comfort was specific to questions relating to a hypothetical victim who “has breasts,” as worded in the surveys (Q1, Q4, Q6, Q7, Q9). This effect persisted for questions relating to both clothed (Q4, Q7) and unclothed women (Q6, Q9). For questions relating to a hypothetical victim who “does not have breasts” (Q2, Q3, Q5, Q8, Q10), comfort levels were not significantly greater in the post-training survey for the adjunct group, compared to the control group. As such, our data demonstrate that the breast adjunct improved comfort levels for trainees in performing CPR on women specifically, regardless of whether the woman’s chest was clothed or unclothed.

Across questions specific to a victim with breasts (Q1, Q4, Q6, Q7, and Q9), the control group exhibited a mean 1.28 point increase in comfort after the class, whereas the adjunct group exhibited a 2.37 point increase. As such, the adjunct group exhibited a 1.9 times greater increase in comfort in performing CPR on individuals with breasts than the control group.

Analyses were also conducted to assess differences in reported comfort in trainee cohorts split by gender. No significant differences in pre-training comfort were found for male or female cohorts, across all survey questions (Table 4, Figures 4 and 5). For questions specific to a victim with breasts (Q1, Q4, Q6, Q7, and Q9), male trainees exhibited significantly greater post-training comfort levels in the adjunct group than in the control group (p=0.005) [Table 5, Figure 6].

Post-training comfort levels for female trainees was not significantly greater in the adjunct group than the control group, although the p-value was on the lower end (p=0.063). These findings suggest that the greater increase in reported comfort in performing CPR on women after using the breast adjunct may be primarily driven by changes in male trainee comfort. For both trainee gender cohorts, no significant differences in mean post-training comfort levels were found across questions not specific to CPR on women (Q2, Q3, Q5, Q8, Q10) [Table 5, Figure 7].

4 Discussion

Several factors contribute to bystanders’ hesitancy to perform CPR on women. A national survey study found that hesitancy may stem from fear of inappropriate touching and legal accusations of assault.¹⁰ Social norms, stigma about touching women, the fear of injuring the victim, unsure hand placement due to breasts, the belief that women are generally healthier than men, and the perception that women are overreacting have been identified as potential explanations based on interviews with US adults.^10,19 These factors are typically not adequately addressed in CPR classes, with limited female representation in CPR training materials.²⁰

We believe that the increased reported comfort with providing CPR to individuals with breasts can be attributed to two key elements: familiarization and challenging misconceptions. First, allowing trainees to practice CPR with the breast adjunct increases their comfort through familiarization. Practicing on a female-like anatomy may help to normalize the process of exposing, delivering chest compressions, and applying an AED to individuals with breasts. Second, and perhaps more indirectly, introducing female-like anatomy to male-centric CPR training challenges dangerous misconceptions by demonstrating that women are also susceptible to sudden cardiac arrest and benefit from CPR.¹¹

The average EMS response time to the curb is about 7 minutes (exceeding 14 minutes in rural settings), and survival rates from witnessed cardiac arrest decrease by 7-10% for every minute an individual goes without CPR. Thus, bystander CPR proves to be an essential component in improving OHCA outcomes.^21,22 Promoting more diverse representation in CPR education may help improve equity in high quality bystander CPR, promoting a victim’s chance for survival, irrespective of their anatomy. 

5 Limitations

Our study has several limitations. As a preliminary proof of concept survey, this study assessed a small sample size (n=58 control; n=21 experimental). Our sample was disproportionately white and Asian—our adjunct group had only one participant of Hispanic or Latino or Spanish Origin—and thus does not adequately reflect a representative community population. Further, our study may exhibit selection bias, as the participants in our study were individuals who actively sought CPR education and thus may not reflect the same attitudes or responses to gender inclusive CPR educational interventions as the general public. Age groups were not collected in our surveys; however, the rough age range of participants in this MassCPR training was 18-25 years old, including undergraduate and graduate students.

Each student pair was assigned to one specific manikin for the entire class; due to the limited number of available breast adjuncts and the large class sizes, the adjunct sample size (n=21) was smaller than our control (n=58). Student assignments to the control and adjunct groups were not randomized by the instructors. Rather, students who used the adjunct during the entire class voluntarily chose to practice on a manikin with the adjunct, which introduces another source of selection bias. The use of non-parametric statistical testing permitted the inclusion of non-equal sample sizes.

Lastly, in any survey study, there is the possibility of social desirability bias, as participants hope to portray themselves in a favorable light, and may end up exaggerating their responses in the post-survey. However, the robust increase in reported comfort levels between groups, combined with the similar group makeups, in a singular, controlled, isolated setting suggests that the breast adjunct does indeed improve comfort levels for trainees in performing CPR on women.

6 Future directions

The use of training tools in CPR classes that accurately represent the patient populations that CPR-trained bystanders serve is essential. As the first study to assess the impact of manikin breast adjuncts during CPR training, this study suggests the potential benefit of introducing female manikins and breast adjuncts more broadly in CPR training. With the potential for upcoming changes in CPR training guidelines, the initiation of randomized control trials that assess the efficacy of female manikins and breast adjuncts is essential for eliminating sex disparities in EMS outcomes.

Studies that investigate the influence of seeing a breast adjunct versus practicing chest compressions on the adjunct, that compare breast adjunct and female manikin efficacy, and that assess the relative impact of breast adjuncts compared to verbal instruction about CPR on women are reasonable next steps. Given the positive results of this exploratory study, implementing breast adjuncts or female manikins, along with other forms of diversity such as bariatric, obstetric, and racial representation, in CPR training suggests the need for further study.

7 Conflicts of Interest

Sabrina C. Liu, Abigail E. Schipper, Charles S. M. Sloane, Ethan Wang, and Roanna Zou are co-inventors on a provisional patent application describing the breast adjunct device presented here.

Terminology disclaimer: Current literature on bystander CPR frequently separates people along the gender binary, which influences the language used in this article. For the purposes of this article, we equate being “female” and “a woman” with having developed breast tissue. However, as a team, we recognize that care must be taken to respect individuals’ gender identities. Not all women have breasts, and not all individuals with breasts are women.

List of abbreviations

AHA: American Heart Association

CPR: cardio-pulmonary resuscitation

AED: automated external defibrillator

OHCA: out-of-hospital cardiac arrest

References