Cardiology

Chest compression quality during CPR of potential contagious patients wearing personal protection equipment

a b s t r a c t

Aim of the study: In this study we aimed to investigate whether changing rescuers wearing N95 masks every 1 min instead of the standard CPR change over time of 2 min would make a difference in effective chest compressions. Methods: This study was a randomized controlled mannequin study. Participants were selected from healthcare staff. They were divided into two groups of two people in each group. The scenario was implemented on CPR man- nequin representing patient with asystolic arrest, that measured compression depth, compression rate, recoil, and correct hand position. Two different scenarios were prepared. In Scenario 1, the rescuers were asked to change chest compression after 1 min. In Scenario 2, standard CPR was applied. The participants’ Vital parameters, mean compression rate, correct compression rate/ratio, total number of compressions, compression depth, correct re- coil/ratio, correct hand position/ratio, mean No-flow time, and total CPR time were recorded.

Results: The study hence included 14 teams each for scenarios, with a total of 56 participants. In each scenario, 14 participants were physicians and 14 participants were women. Although there was no difference in the first minute of the cycles starting from the fourth cycle, a statistically significant difference was observed in the second minute in all cycles except the fifth cycle.

Conclusion: Changing the rescuer every 1 min instead of every 2 min while performing CPR with full PPE may pre- vent the decrease in Compression quality that may occur as the resuscitation time gets longer.

(C) 2021 Published by Elsevier Inc.

  1. Introduction

In cases of cardiac arrest, the Quality of chest compressions during cardiopulmonary resuscitation (CPR) declines dramatically after a short time, which adversely affects the outcome [1]. When the guide- lines are examined, it has been seen that the importance of chest com- pressions has increased from past to present, and international resuscitation councils consider effective chest compressions as the key to improved survival. [2,3]. chest compression quality and effective per- formance time may decrease owing to rescuer characteristics (e.g., sex, weight, and muscle fitness) and fatigue [4]. The current CPR guidelines recommend that the rescuers should change every 2 min.

Due to the fact that Healthcare workers are on the front lines during the Covid-19 era, the Incidence of infection and mortality are high among them [5]. The European Resuscitation Council (ERC) and several other associations have published guidelines for basic and advanced life

* Corresponding author at: Department of Emergency Medicine, Faculty of Medicine, Karabuk University, 78100 Karabuk, Turkey.

E-mail address: [email protected] (B. Cekmen).

support for COVID-19 cases, which recommend that all rescuers should wear Personal protective equipment , including an N95 mask, dur- ing CPR [3,6]. Medical masks significantly impair strenuous and physical activities and negatively affect cardiopulmonary capacity [7]. This situa- tion is believed to make breathing difficult, increase fatigue, and reduce compression quality. In the light of this information, it was hypothe- sized that how often rescuers switch roles has an effect on fatigue and compression quality in cases of cardiac arrest in which rescuers are mandated wear N95 mask [8,9]. This is the first study toinvestigate whether changing rescuers wearing N95 masks every 1 min instead of the standard CPR change over time of 2 min would make a difference in effective chest compressions.

  1. Methods
    1. Study design

This study was a Randomized controlled simulation study. The study was implemented on a mannequin, according to a designed scenario,

https://doi.org/10.1016/j.ajem.2021.12.009 0735-6757/(C) 2021 Published by Elsevier Inc.

using the “compression-only cardiopulmonary resuscitation” method indicated in the European Resuscitation Council CPR guideline.3 The re- lationship between the obtained data was then investigated.

    1. Study settings

This study was performed with volunteer healthcare workers from January 20, 2021 to March 20, 2021 in Karabuk University Training and Research Hospital, Karabuk, Turkey, which is a Level 3 Emergency Medicine Center. The ethics committee of Karabuk University approved the study (Number:2020/378). Resusci Anne(R) Simulator with SimPad(R) mannequin was used in the study.

    1. Participants

Participants were selected from healthcare staff, including physi- cians, nurses, and paramedics, working at the Karabuk University emer- gency department. They were divided into two groups of two people in each group. The participants included in the study were randomized using an online randomization program (www.random.org) to distrib- ute the male-female staff and physician-assistant health personnel equally in both scenarios. Participants’ age, sex, height, weight, working years, and professional positions were recorded.

Those who were aged>50 years, had any physical disabilities or co- morbid diseases, had a body mass index (BMI) of <18.5 or > 39.9, and were involved in a strenuous activity (such as CPR practice or exercise) within the last 2 h before the study were excluded.

In-house trainings on basic life support and advanced life support are held regularly in our hospital at 6-month to 1-year intervals. How- ever, to provide pre-study standardization, 45-min training on CPR was conducted by European Resuscitation Council CPR guideline. Partic- ular emphasis was given to the two-rescuer CPR sequence and high- quality chest compression skills. Each participant then performed two- rescuer chest compression-only CPR on the mannequin for a total of 30 min under the supervision of the instructors. Participants received written and verbal information about the study and provided written informed consent.

    1. Scenarios

The scenario was implemented on a CPR mannequin that measured compression depth, compression rate, recoil, and correct hand position. Both scenarios were performed on a standard hospital bed with CPR board on it, representing a patient with asystolic arrest. All participants were provided with the same standard type N95 mask (Respiratory Pro- tection Mask, Z series, FFP2-267 type, MFA(R), TURKEY) as well as a gown and a face shield. Participants were asked to perform chest com- pressions at a rate of 100-120 beats per minute, at a depth of 5-6 cm, and to allow adequate chest recoil, as recommended in current guide- lines. To standardize the number of compressions, a metronome was set at 110 beats per minute. Participants were allowed a short time of observation to observe the accuracy of the compression depth, hand po- sition, compression rate, and recoil for trial purposes, but they were prevented from observing this when the scenario was initiated.

While creating the scenarios, the cycle term was defined as the end

of the 2nd minute. A total of 9 cycles were planned for both scenarios. As in standard CPR, a 10-s Patient evaluation interval was given in the 2nd minute. Two different scenarios were created for the groups, named Scenario 1 and Scenario 2. The scenario created for Group 1 was named Scenario 1. During scenario 1, the participant was changed after each minute of compression, ensuring these changes were under two seconds to minimize mean No flow time. At the end of the 2nd minute, there was a 10-s patient evaluation interval. In scenario 2, two

minutes of compression was applied, after this interval, the other partic- ipant continued with 2-min compressions. The participants were in- formed on how frequently they would need to alternate in each scenario, but they were not informed about how long they administered CPR in total.

    1. Measurements

The participants’ heart rate, respiratory rate, systolic and diastolic arterial blood pressures, O2 saturation, and modified Borg perceived exertion scale scores were recorded before and at the end of the scenarios [10].

Mean compression rate calculated by the device, correct compres- sion rate ratio, total number of compressions, compression depth, cor- rect recoil ratio, correct hand position ratio, mean no-flow time, and total CPR time were recorded. Curves representing the compression depths and recoil amounts of the compressions performed per minute in the CPR cycles of the groups were obtained using the Session Viewer Program (Version 7.2.7248, SimVentures(C)2021), from which the data of the model could be obtained (Fig. 1). Compression curves in each minute were counted one by one for both groups, and compression depths and recoil amounts were recorded in millimeters as numerical data. These data were statistically analyzed separately for each group.

    1. Outcomes

Compression depths were determined and compared for both groups as the primary outcome of the study. Parameters for vital signs and changes in the modified Borg perceived exertion scale scores were evaluated as secondary outcomes.

    1. Statistical methods

Statistical analyses were performed using SPSS version 15.0 soft- ware. Normal distribution of the variables was examined using visual (histogram and probability graphs) and analytical methods (Kolmogo- rov-Smirnov/Shapiro-Wilk tests). Descriptive statistics were expressed as mean +- SD for normally distributed variables, median (IQR) for non- normally distributed variables, and n(%) for categorical variables. For comparing two independent groups, Student’s t-test was used for nor- mally distributed variables, Mann-Whitney U test for non-normally dis- tributed variables, and chi-squared or, where appropriate, Fisher’s test for categorical variables. The differences between the groups in the first and last minutes of the scenarios were compared using the Wilcoxon test. Cases in which the p-value was <0.05 were considered as statistically significant.

  1. Results

A total of 30 randomized teams with 60 participants were formed. In Scenario 1, one team was excluded from the study due to a technical perception error in the mannequin; in Scenario 2, one team was excluded due to errors in adherence to the scenario. The study hence in- cluded 14 teams each for Scenarios 1 and 2, with a total of 56 partici- pants. In each scenario, 14 participants were physicians and 14 participants were women. The demographic characteristics of the par- ticipants and their vital signs, including start-to-end heart rate, SpO2, systolic and diastolic blood pressures, respiratory rate, and modified Borg perceived exertion scale scores,are shown in Table 1. There was no significant difference between the groups in terms of age, sex, height, weight, BMI, and professional experience in terms of employ- ment years (p > 0.05). At the beginning of the scenarios, no significant differences were noted in vital signs other than heart rate. Although there was a significant difference between the two groups in terms of heart rate at the beginning, the higher heart rate of Group 2 (88.5 +- 10.3 vs. 96 +- 12.2) was not clinically significant.

Image of Fig. 1

Fig. 1. An example of calculating the compression depths and recoil amounts of compressions per minute in the CPR cycles of the groups.

Table 2 shows how the groups performed in the scenarios. There was no statistical difference between the groups in terms of mean com- pression rate, correct compression rate ratio, scenario duration, total number of compressions, compression depth, correct recoil ratio, cor- rect hand position ratio, and mean no-flow time (p > 0.05).

When the compression depths of the groups during the scenario

were compared for each minute, no statistically significant differences were noted in both the first and second minutes of the first three cycles (Table 3). However, although there was no difference in the first minute of the cycles starting from the fourth cycle, a statistically significant dif- ference was observed in the second minute in all cycles except the fifth cycle (Fig. 2).

When the differences in the first and last minutes of the scenarios between the groups were examined, no differences were observed in the compression depth in Group 1 (p = 0.92), but a significant decrease was observed in Group 2 (p = 0.005; Table 4).

  1. Discussion

The data from our study suggests that when CPR is performed with PPE, it becomes increasingly difficult to maintain effective compression depth until the end of the cycle using the standard rescuer change time

Table 1

Groups’ Demographic characteristics and Vital Parameters.

Variable

Group 1 (n = 28)

Group 2 (n = 28)

p

Age

29.5 +- 5.6

28 +- 6

0.34

Sex,male (n,%)

14 (%50)

14 (%50)

1

of 2 min. However, compression depth does not change in the following minutes of CPR when the rescuers change every 1 min.

Before the scenarios in this study were implemented, participants experimented on the mannequin for variables affecting the Quality of CPR, such as correct hand position and compression rate. A metronome was used for establishing a rhythm for performing the compressions and aiding the participants. However, no warnings or interventions were given or performed that would affect the compression depth. Con- sidering this situation, our study standardized many of the factors that affect the efficacy of CPR and largely associated the concept of CPR qual- ity with compression depth.

There are numerous studies in the literature that have investigated how often rescuers change while performing CPR [11,12]. Further, there are some studies demonstrating that compression quality changes depending on mask quality (N95 vs. surgical mask) [8,13]. Our study differs from other studies in the literature as it examines both compres- sion depth variation over time and the rescuers changing time in CPR performed by rescuers wearing full PPE. Interruptions to cardiac com- pression for more than 10 s have adverse effects on the outcome [4]. In Animal experiments, it has been shown that longer intervals cause a decrease in coronary perfusion pressure [14]. In our study, mean no flow time, which had an effect on clinical outcome, was not different be- tween the groups.

In our study, no statistically significant difference was found be- tween the groups in initial and final vital signs. Considering this to- gether with the number of compression, 1-min changes were shown to yield better results despite the same exertion and fatigue level. This shows that even if 1-min shift time does not provide physiological ben- efits to the rescuer, it does help to keep the compression quality con-

Height (meter)

1.70 +- 0.7

1.70 +- 0.6

0.92

stant for a longer period of time.

Weight (kilogram)

75.5 +- 14.2

71.9 +- 15.9

0.38

BMI

25.8 +- 4

24.6 +- 4

0.24

Profession, Doctor (n, %)

14 (%48.3)

15 (%51.7)

0.78

Working year, median(IQR)

2 (6.5)

1.5 (1.3)

0.25

Table 2

Before CPR

The performances of the groups in the scenario.

Pulse

88.5 +- 10.3

96.6 +- 12.2

0.01*

Variable

Group 1

Group 2

p

SpO2 (%)

97.7 +- 0.7

98.1 +- 1.1

0.23

(n = 28)

(n = 28)

Sistolic Blood Pressure

116.6 +- 12.8

121.7 +- 15.3

0.17

Diastolic Blood Pressure

75.3 +- 11.8

76.1 +- 10.1

0.80

Average chest compression rate (bpm)

111.1 +- 2.3

110 +- 2.2

0.25

Respiratory rate

17.5 +- 2.4

17.7 +- 3.1

0.81

Accurate compression rate ratio (%)

92.7 +- 3.9

92.5 +- 7.7

0.90

Borg Score, median(IQR)

9(2)

8.5(2)

0.97

Scenario duration (minute)

1199.2 +- 4.2

1202 +- 8.47

0.29

Total number of compressions

2033 +- 58.7

2049 +- 45.1

0.43

End of the CPR

Compression depth (mm), median(IQR)

54 (3.2)

52 (5.7)

0.11

Pulse

120.2 +- 22.8

125.9 +- 19.1

0.31

Correct recoil rate (%), median(IQR)

79 (36)

82 (27)

0.93

SpO2 (%)

97.3 +- 1.01

97.5 +- 1.1

0.62

Correct hand position ratio (%), median(IQR)

98.5(4)

98(7)

0.42

Sistolic Blood Pressure

123.6 +- 13.4

129.7 +- 13.4

0.09

Mean no flow time (minute), median(IQR)

5(2)

6(2)

0.09

+- mean +- standart deviation. n (%) categoric variables.

Diastolic Blood Pressure

76.5 +- 8.7

76.5 +- 11.5

0.99

Respiratory rate

25.8 +- 6.3

27.7 +- 5.5

0.24

Borg Score, median(IQR)

13(5)

13(8)

0.28

m(IQR) median (interquartile range).

Table 3

Comparison of the chest compression depth of the groups during the scenario.

Cycles

Scenario Intervals (time)

Group 1 (mm)

Group 2 (mm)

p

1

00:00-01:00

53.2 +- 6.4

53.9 +- 7.4

0.52

01:00-02:00

51.6 +- 6.6

53.2 +- 9

0.49

2

02:10-03:10

54.9 +- 6.8

53.3 +- 7.0

0.33

03:10-04:10

52.3 +- 7.8

49.8 +- 7.0

0.17

3

04:20-05:20

54.2 +- 9.4

52.0 +- 8.2

0.74

05:20-06:20

53.4 +- 5.7

49.6 +- 10.1

0.53

4

06:30-07:30

55.1 +- 6.4

52.1 +- 5.0

0.46

07:30-08:30

54.2 +- 3.4

49.0 +- 4.9

0.006*

5

08:40-09:40

55.4 +- 6.0

55.2 +- 6.9

0.61

09:40-10:40

54.4 +- 5.9

51.8 +- 11.2

0.21

6

10:50-11:50

54.1 +- 7.3

54.6 +- 8.6

0.71

11:50-12:50

54.6 +- 7.8

49.2 +- 8.6

0.02*

7

13:00-14:00

55.4 +- 10.8

52.1 +- 9.8

0.24

14:00-15:00

53.6 +- 5.4

49.3 +- 9.0

0.04*

8

15:10-16:10

54.8 +- 8.8

49.8 +- 9.1

0.43

16:10-17:10

53.7 +- 7.6

45.0 +- 8.5

0.003*

9

17:20-18:20

54.0 +- 7.0

50.9 +- 10.0

0.25

18:20-19:20

54.0 +- 6.3

49.0 +- 13.4

0.002*

Image of Fig. 2

Fig. 2. The compression depths of the groups during the scenario were compared for each minute.

No statistical significance was found in the modified Borg perceived exertion scale scores before and after CPR. We believe that this result of our study can be adequately explained considering that the Borg scale is a scale based on the subjective evaluation of the participant and de- pends on interviewer-participant communication.

    1. Limitations

Our study has some limitations. First, this is a simulation study con- ducted in a controlled setting with patient and disease factors ruled out. This may have caused changes in participants’ performance. Second, Hands-only CPR was performed on the mannequin, ventilation was not performed, and the rib cage-resistance effect was disregarded. As a result, the effects of these factors on changes in performance remain unknown. Further studies with bigger sample size were needed.

Table 4

Comparison of the chest compression depth between the groups in the first and last minute of the scenarios.

00:00-01:00 18:20-19:20 p

Group 1, mm 53.2 +- 6.4 54.0 +- 6.3 0.92

Group 2, mm 53.9 +- 7.4 49.0 +- 13.4 0.005*

  1. Conclusions

We think that changing the rescuer every 1 min instead of every 2 min while performing CPR with full PPE may prevent the decrease in compression quality that may occur as the resuscitation time gets longer.

Conflicts of interest

The authors declare no conflicts of interest.

Funding

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

Acknowledgements

First, we want to thank to Ersin Cekmen and Caner Yavas for their precious contributions. The authors would like to thank the doctors and nursing staff from Karabuk University ED for their support and will- ingness to participate.

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