Comparison of standard and alternative methods for chest compressions in a single rescuer infant CPR: A prospective simulation study.

OBJECTIVE: The aims of this study were to develop a novel three-finger chest compression technique (pinch technique; PT) and an assistive device chest compression technique (plate-assisted technique; PAT) and compare these techniques with conventional techniques.
DESIGN: Prospective, crossover manikin study.
SETTING: Pediatric emergency department at a tertiary care academic center.
SUBJECTS: Fifty medical doctors and medical students.
INTERVENTIONS: Using a manikin, fifty participants performed five different chest compression techniques-two 2-finger techniques (TFT1 and TFT2), two PTs (PT1 and PT2), and the PAT-for 2 minutes with 2 minutes of rest in a randomized sequence.
MEASUREMENTS AND MAIN RESULTS: The compression depth (CD), compression rate, recoil, and finger position were recorded. At the study conclusion, each participant completed a 5-point Likert scale-based questionnaire on fatigue, satisfaction and difficulty of performing each technique. The mean CDs were 32.9 mm (TFT1), 30.3 mm (TFT2), 37.3 mm (PT1), 35.0 mm (PT2) and 40.1 mm (PAT) (p<0.001). TFT2 achieved the highest frequency of complete chest recoil, followed by PT1 and TFT1 (88.9%, 86.9%, and 81.4%, respectively, p = 0.003). The highest percentage of correct finger position was achieved by the PAT, followed by the PT1 and PT2 (93.4%, 83.1%, and 80.1%, respectively, p = 0.016). PAT use resulted in higher participant satisfaction, less fatigue, and less difficulty than the other four techniques.
CONCLUSION: Our new chest compression methods using three fingers and assistive plates showed better CD results than the conventional 2-finger technique.

RCT Entities:   Population Interventions Outcomes

Introduction

Pediatric cardiac arrest has a low rate of survival to hospital discharge compared to that of adults. The overall survival rate of out-of-hospital cardiac arrest in infants ranges from 6% to 27%, with poor neurological outcomes [1-3]. To improve the survival rates of pediatric cardiac arrest victims, current global guidelines, such as those of the European Resuscitation Council (ERC), American Heart Association (AHA), and Korean guideline for cardiopulmonary resuscitation (CPR), strongly recommend the delivery of high-quality chest compressions [4-6].

Both the ERC and AHA guidelines recommend using the 2-finger technique (TFT) in the center of the chest (the lower half of the sternum) for single-rescuer infant CPR, while for two or more rescuers, the 2-thumb encircling hands technique (TTHT) is recommended [4, 5]. Compared with the TFT, the TTHT was reported to consistently achieve higher blood and coronary perfusion pressure and greater compression depth (CD) in a variety of animal and manikin models [7-11]. However, most resuscitation guidelines recommend the TFT method for single-rescuer infant CPR because of the longer hands-off time and difficulty of postural change [11].

Several studies have investigated whether different methods deliver better chest compressions than TFT for single-rescuer infant CPR [12-15]. To overcome the insufficient CD of the TFT and alleviate discomfort in the user’s fingers after prolonged compressions, we have developed two new compression methods: the pinch technique (PT) and the plate-assisted technique (PAT). The PT uses three fingers, which makes chest compressions easier. The PAT uses the thumb, index and middle fingers, along with a round plate. We performed a comparative analysis of two types of TFT, two types of PT and PAT during an infant CPR simulation.

Materials and methods

The study was approved by the Institutional Review Board (approval IRB No: H-1606-048-770) of Seoul National University Hospital. Each participant received oral and written information about the study and the study protocol before providing written informed consent.

Study design

This prospective manikin trial was conducted between October and November 2016 at a tertiary teaching hospital. A total of 50 individuals participated in the study, including 17 medical doctors (five interns and 12 emergency medicine residents) and 33 medical school students. All participants received basic life support (BLS) provider education. Chest compressions were performed using the five different techniques. TFT1 compression used the index and middle fingers; TFT2 compression used the middle and ring fingers; PT1 compression used the thumb, index and middle fingers; PT2 compression used the thumb, middle and ring fingers; and PAT compression used the new device technique (Fig 1). The PAT device is made of rubber, is circular in shape and has a partition that divides the device into three areas for the thumb, index finger, and middle finger. A 1.0 cm in diameter circular piece is attached to the bottom of the device to simplify finding the correct compression point position (Fig 2). This device is made by the Department of Medical Engineering at Seoul National University as our request and is not patented and is not commercially available.

Fig 1

Postures for the cardiac compressions.

TFT1: index-middle fingers; TFT2: middle-ring fingers; PT1: thumb-index-middle fingers; PT2: thumb-middle-ring fingers; PAT: thumb-index-middle fingers with plate.

Fig 2

The new infant compression device (A: lateral view, B: viewed from above, C: viewed from below).

A 3-month-old infant manikin (Resusci® Baby QCPR® by Laerdal Medical) was used and was fitted with a SimPad PLUS with Skill Reporter (Laerdal Medical). The manikin was placed on a table that was 1.0 m high and reached the approximate waistline of the rescuers. Prior to conducting the study, all the participants received a 10-minute training session on compression rate, compression location and CD, according to current CPR guidelines using the standard TFT. Additionally, a brief introduction to the PT and PAT was given.

CPR was performed on the manikin for 2 minutes with each technique, followed by a 2-minute rest. The participants did not receive feedback regarding their performance during the study period. At the end of each technique, the participants completed the 5-point Likert scale-based questionnaire. The questionnaire recorded the fatigue, satisfaction and difficulty experienced by the rescuers.

Measured outcomes

The primary outcome was the CD (mm) during CPR. The secondary outcomes were compression rate (compression/min), correct compression rate (%), correct CD (%), correct chest recoil (%), correct finger position (%), and the 5-point Likert scale-based questionnaire for satisfaction, fatigue and easiness.

Data collection

The chest compression performance data were collected using the SimPad Skill Reporter. For each technique, the total number of chest compressions (compression/min), CD (mm), and the percentages of correct CD, adequate compression rate, compression with correct finger position, and complete recoil of the chest were recorded. The correct finger position was specified as just below the nipple line in the middle of the chest in a 1.0 × 1.0 cm square. We defined correct CD as ≥ 40 mm, correct compression rate as 100–120/min, and complete recoil as the manikin’s chest returning to its original position.

Statistical analysis

The data were analyzed using the SPSS 22.0 statistical package (SPSS, Inc., Chicago, IL, USA). The values of continuous variables are expressed as the means ± standard deviation (SD). Linear mixed-effect models for repeated measures were used to compare the five chest compression methods. The fixed effects in the models were the compression methods, period, and interaction between the compression methods and period; the study participants were treated as the random effect. A post hoc analysis was performed using the Bonferroni method. A Bonferroni corrected p-value <0.05 was considered statistically significant.

The sample size was calculated based on chest CD. A sample size of 46 rescuers provided an alpha of 0.05 and a power of 80%, which would allow detection of a between-subject difference of 0.6 SD, assuming a between-subject difference in depth of 4 mm. To account for 8% potential drop-out, we planned to enroll a total of 50 rescuers.

For the credible randomization of the serial sequential measurements of the different chest compression techniques, we used the Williams design with 5 x 5 crossovers. The Williams design is a special combination of crossover and Latin square designs [16].

Results

The study participants included 50 medical doctors and medical school students (33 males; 66%), including 12 resident physicians (24%), 5 intern physicians (10%) and 33 medical students (66%). The mean participant age was 26.0 ± 3.2 years.

Primary outcomes

The compression methods compared in this study are shown in Table 1. The effect of the interaction between compression method and period on the CD was not significant (p>0.05). The period was not significantly different among the compression methods (p = 0.28). The CD was significantly different among the compression methods (p<0.001). The mean CDs of each group were 32.9 mm (TFT1), 30.3 mm (TFT2), 37.3 mm (PT1), 35.0 mm (PT2) and 40.1 mm (PAT). The mean CD was best when PAT was used, while the TFT2 produced the lowest CD. All pairwise comparisons were significantly different for CD, except for TFT1 vs. PT2 and PT1 vs. PT2 (Fig 3A).

Table 1

Comparisons of chest compression quality of the five different techniques.

CompressionMethodParameter	TFT1	TFT2	PT1	PT2	PAT
	Mean ± SD					p-value
CPR Quality
Depth of compression (mm)	32.9 ± 0.6	30.3 ± 0.7	37.3 ± 0.4	35.0 ± 0.6	40.1 ±0.3	<0.001*
Rate of compression (compression/min)	107.3 ± 9.3	103.3 ± 11.9	109.1 ± 7.8	107.8 ± 7.3	109.8 ± 7.8	0.004*
Correct rate (%)	77.6 ± 34.5	78.5 ± 31.3	85.1 ± 27.0	82.4 ± 30.3	95.0 ± 8.3	<0.001*
Correct depth (%)	22.1 ± 31.3	13.2 ± 23.1	55.9 ± 24.1	29.7 ± 36.3	76.5 ±23.2	<0.001*
Correct finger position (%)	79.7 ± 34.3	75.8 ± 35.1	83.1 ± 28.3	80.1 ± 31.6	95.4 ±16.5	0.015*
Correct chest recoil (%)	86.9 ± 25.4	92.8 ± 18.9	88.9 ± 18.6	81.4 ± 31.6	74.7 ± 28.9	0.003*
Questionnaires
Satisfaction	2.6 ± 1.1	2.5 ± 0.9	3.2 ± 1.0	3.1 ± 0.9	3.8 ± 1.0	<0.001*
Fatigue	3.8 ± 1.0	3.9 ± 0.9	3.5 ± 0.8	3.6 ± 0.8	2.6 ± 0.9	<0.001*
Difficulty	2.5 ± 1.1	2.6 ± 0.9	3.1 ± 0.8	2.9 ± 0.9	4.0 ± 0.9	<0.001*

TFT: Two Finger Technique, PT: Pinch Technique, PAT: Plate-assisted Technique, CPR: Cardiopulmonary Resuscitation

*A statistically significant by linear mixed-effect mode

Fig 3

Linear mixed-effect model.

The post hoc analysis was performed using a Bonferroni method. A Bonferroni corrected p-value <0.05 was considered statistically significant. A. Depth of compression (mm), B. Correct depth (%). a: TFT1, b: TFT2, c: PT1, d: PT2, e: PAT.

Secondary outcomes

The interactions between protocol and period were not significant for any secondary outcomes (p>0.05). The PAT showed the best results for the compression indices (rate, correct rate, correct depth, and correct finger position), while PT1 exhibited the best results among the techniques that did not use a device (Table 1). Only the PAT achieved a mean target depth of ≥40 mm, which was significantly greater than the depths achieved with the other techniques (p<0.001, Fig 3B). All the techniques achieved a target compression rate of 100–120/min (p = 0.004). The highest percentage of chest recoil was recorded for TFT2 (92.8%), followed by PT1 (88.9%); the lowest percentage was achieved by the PAT (74.7%), and this difference was statistically significant (p = 0.003). The highest correct finger position percentage was recorded using the PAT (95.4%), followed by PT1 (83.1%), and the lowest percentage was achieved with TFT2 (75.8%) (Table 1).

The participants completed a questionnaire after each technique was performed. The questionnaire consisted of items regarding satisfaction with the cardiac compression, the degree of difficulty and the degree of fatigue; these were evaluated with a 5-point Likert scale (Table 1). The PAT had the highest satisfaction score, lowest difficulty of compression score and lowest fatigue score. TFT2 had the highest fatigue score. All items exhibited significant differences (Table 1). A post hoc analysis showed that the PAT obtained better scores than the other compression techniques for satisfaction, fatigue and easiness (Figures E, F, and G in S1 File).

Discussion

In this study, we developed and evaluated a new compression technique (PT) and a new chest compression device (PAT). To the best of our knowledge, this is the first study to examine the use of a device for infant chest compressions performed by a single rescuer. When the five chest compression techniques were compared, the PAT exhibited the best results, followed by the PT1. According to our results, the PAT can be recommended for optimal chest compression. If the PAT is unavailable, the PT1—a technique using the index and middle fingers and the thumb—is recommended as a single-rescuer infant compression technique rather than conventional TFT.

For single-rescuer infant CPR, the TFT is currently recommended in global and regional CPR guidelines [4-6]. However, because the TFT method is less effective than the two-thumb method for chest compressions, various studies have examined the use of other chest compression methods to replace the two-finger method [12-15]. In this study, we proposed a PT that involved adding the thumb to the conventional TFT. The fatigue or discomfort that can occur when only two fingers are used seems to be relieved by adding the thumb. Furthermore, the development and application of a plate that can be grasped with three fingers, including the thumb, resulted in better chest compression indices and greater satisfaction than the conventional TFT and the newly developed PT. However, the recoil results of the chest compression index for the PAT were significantly lower than those of the PT and TFT.

As with adult BLS, it is important to maintain adequate chest CD when providing pediatric life support [4, 5, 17]. However, several manikin studies have shown that the TFT results in suboptimal CD, and some have shown that TFT only achieves a depth of approximately 25 mm [12, 13]. To address this problem, several new infant chest compression techniques and tools have been developed and evaluated. A study by Fakhraddin et al. reported that a new compression technique using the thumb and index finger improved the chest compression index results [12]. The thumb is more powerful than the other fingers; thus, use of the thumb is optimal for improving CD. The new technique has demonstrated good results that are similar to those of our study, particularly for achieving adequate CD and avoiding fatigue. The CD of this new compression technique was similar to that of TTHT (33.3 mm vs. 33.1 mm) [12]. As with the Fakhraddin et al. [12] study, the PT proposed in our study was beneficial, as the results showed that the finger-pressing method that included the thumb without using an instrument was useful. In this study, the TFT was performed using only the index and middle fingers or the middle and ring fingers of the participant’s right hand. When the chest pressure index was compared between the two methods used for the TFT, as in the previous study, the mean CD of the index and middle fingers technique was greater; however, the difference was not statistically significant (32.9 mm vs. 30.3 mm, p = 0.05). This result is similar to those of a previous study in which the right-hand index and middle fingers method showed the best results among several TFT methods [18].

A recent study of another new compression technique—the knocking-fingers technique—found high-quality chest compression and ventilation with minimal interruption of chest compressions [15], suggesting that it is an effective alternative chest compression technique for infant CPR. In a computed tomography-based study of a new compression method, the results suggested that the greater the compression area, the higher the risk of damage to the external organs [19]. The knocking-fingers technique had the smallest area of chest compression, with a median vertical length of 12 mm and a median horizontal length of 30 mm [15]. Although we used a related device, the compression area of the instrument used in our study was smaller than that of the knocking-fingers method, which could further reduce the risk of organ damage.

Both the traditional TFT and a new PT exhibited suboptimal CD, whereas the PAT showed a depth that was sufficient to recommend it. The technique with the highest percentage of correct finger positioning was the PAT, followed by the PT1; the TFT2 had the lowest percentage of correct finger position. The PAT showed the best results for depth, rate, correct compression rate, correct CD, and correct finger position. The participants felt at ease and were satisfied with the new device. The strengths of the PAT are as follows: 1) the compression position is limited to only the 1-cm diameter of the device, 2) it is easy to place the fingers and maintain the finger position, and 3) it is not easily displaced on the skin. Despite these advantages, the PAT showed the poorest result in terms of compression relaxation among the tested techniques. It may be difficult to determine sufficient relaxation because the rescuer makes contact with the skin indirectly, through the plate. When using the PAT, it is important to emphasize that the rescuer should not lean on the plate when the chest is recoiling.

If the chest recoil index results for the PAT could be improved, we would recommend the PAT as the best method for single-rescuer infant CPR. However, the effect of this method has been confirmed only in one well-designed manikin study; therefore, verification in a clinical setting or animal model is needed.

Limitations

Our study had some limitations. First, the chest stiffness and resistance and size of manikin models may not accurately represent these characteristics in humans, and the experimental conditions may not accurately represent real-life situations. In addition, it is possible that the results would be different under more stressful conditions. Second, we did not measure the pressure quality, as some simulation studies have, to assess compression quality [7, 10]. However, the usefulness of the chest compression indices recorded during infant manikin tests has been confirmed in several studies, and the results of our study are considered reliable under these circumstances [8–11, 15, 18]. Third, rescue ventilations were not included in our study protocol. Because the purpose of this study was to compare five different chest compression techniques and the chest compression indices of single-rescuer infant CPR, the study was conducted without using rescue ventilation. Fourth, the participants varied and included residents, interns, and medical students; however, no significant difference was found when comparing the quality indices of the three groups (data not shown). The participants were likely to have similar characteristics given that they did not have experience with infant CPR and were all within 2 years of obtaining their BLS certification. Finally, for future studies to evaluate the effectiveness of the techniques, the participants should include experienced doctors and healthcare practitioners since the current study only included medical students and residents.

Conclusions

Our new PT and PAT showed better results for CD than the conventional TFT. The PAT resulted in less fatigue for the rescuers and superior CD compared to the other techniques. However, the results were from only manikin models, so external validation of the above findings is needed.

Figure A. Comparison of rate of compression (/mm) between five methods.

Figure B. Comparison of correct rate (%) between five methods.

Figure C. Comparison of correct finger position (%) between five methods.

Figure D. Comparison of correct chest recoil (%) between five methods.

Figure E. Comparison of satisfaction score between five methods.

Figure F. Comparison of fatigue score between five methods.

Figure G. Comparison of easiness score between five methods.

(DOCX)

Click here for additional data file.

3 Sep 2019

PONE-D-19-19476

Comparison of standard and alternative methods for chest compressions in a single rescuer infant CPR: a prospective simulation study

PLOS ONE

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Reviewer #1: Yes

Reviewer #2: Yes

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Reviewer #1: Yes

Reviewer #2: Yes

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Reviewer #1: Yes

Reviewer #2: Yes

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Reviewer #1: After reviewing the PONE-D-19-19476 manuscript entitled “Comparison of standard and alternative methods for chest compressions in a single rescuer infant CPR: a prospective simulation study” some suggestions and clarifications were raised as follows:

The aim of the study was to assess a new technique/device against 4 different techniques on a simulation manikin. In general, the manuscript is well written with minor spelling or grammar mistakes.

After checking the literature, and to my knowledge, this is the only manuscript that evaluated the use of a devise to assist the rescuers in performing CPR. This is a vital area of research since improving CPR in pediatric would rescue many lives.

Please find below some of the suggestions that would improve the quality of the manuscript.

Major suggestions or questions:

1. Why did it take the investigators a long time after the simulation (Oct and Nov 2016) to prepare the manuscript and submit it for publications? Many papers were published during this period on new finger location and numbers since then. (1-5) one of the new techniques has many publications showing its superiority to TFT.

2. The authors used a random cross over method to test the different techniques. Also they mentioned that some of the techniques caused fatigue more than the others. Did the authors check the effect of starting with a harder technique on the performance of participants in the other techniques?

3. Did the authors check the difference in the performance of the participants depending on their levels (doctors, residents and students)?

4. How were the CD, the compression rate, finger position, and the recoil recorded and evaluated? Does the manikin record them?

5. Does the manikin record other parameters like simulated SBP, DBP, mean arterial pressure, and pulse pressure?

6. Did the author account for the primary/dominant hand of the participant? In the text they mentioned that all the participants used their right hand fingers for the compressions. How many participants were left handed? How was the performance of these participants in comparison with the right handed ones?

7. The authors should provide further description or details about the used device in the PAT technique.

a. Is it patented?

b. Is it commercially available? What company invented it?

c. Is there any other device in the market or experimental to compare this device to it?

8. Depending on the author responses to question 7, the conflict of interest of the group would be more clear to the reviewers and the journal.

Minor

1. Spelling mistakes (line 2 Paediatric and line 4, pediatric).

2. On line 145, remove one of “That” after TFT.

3. The description of the dimensions of the circular piece (line 39) must report either the diameter or the radius and not 2 dimensions since it is circle shape. Please modify.

4. Authors must improve the appearance of Table 1. It is hard to get the results as it is now.

5. The orientation of the manikin and the fingers position in figure 1 (PT1 and PT2) is not clear. I suggest a better orientation like the other images.

6. I suggest that the authors move some of the graphs presented in the supplementary sections to the main manuscript body to enrich the article.

7. The numbering of the figures in the supporting information file should start with 1, and the authors should assign a special character to reflect the location of the figure in the supplement file. The authors should check the guidelines of PLoS one for this issue.

1. Ladny J, Smereka J, Rodriguez-Nunez A, Leung S, Ruetzler K, Szarpak L. Is there any alternative to standard chest compression techniques in infants? A randomized manikin trial of the new “2-thumb-fist” option. 2018. e9386 p.

2. Smereka J, Bielski K, Ladny J, Ruetzler K, Szarpak L. Evaluation of a newly developed infant chest compression technique A randomized crossover manikin trial 2017. e5915 p.

3. Smereka J, Szarpak L, Ladny J, Rodriguez-Nunez A, Ruetzler K. A Novel Method of Newborn Chest Compression: A Randomized Crossover Simulation Study 2018. 159 p.

4. Smereka J, Szarpak L, Rodriguez-Nunez A, Ladny J, Leung S, Ruetzler K. A randomized comparison of three chest compression techniques and associated hemodynamic effect during infant CPR: A randomized manikin study 2017. 1420-5 p.

5. Smereka J, Szarpak L, Smereka A, Leung S, Ruetzler K. 2017. Evaluation of new two-thumb chest compression technique for infant CPR performed by novice physicians. A randomized, crossover, manikin trial 604-9 p.

Reviewer #2: Dear authors,

Thank you for the opportunity to review the manuscript "Comparison of standard and alternative methods for chest compressions in a single rescuer infant CPR: a prospective simulation study".

A very interesting study concerning an important medical field that I have read with great interest.

I wish you all the best for publication.

Kind regards

**********

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Reviewer #1: Yes: Moustafa Al Hariri

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2 Oct 2019

Response to Reviewers

We would like to thank the reviewer for the careful and thorough reading of this manuscript and for the thoughtful comments and constructive suggestions.

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

________________________________________

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

________________________________________

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

________________________________________

4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

________________________________________

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: After reviewing the PONE-D-19-19476 manuscript entitled “Comparison of standard and alternative methods for chest compressions in a single rescuer infant CPR: a prospective simulation study” some suggestions and clarifications were raised as follows:

The aim of the study was to assess a new technique/device against 4 different techniques on a simulation manikin. In general, the manuscript is well written with minor spelling or grammar mistakes.

After checking the literature, and to my knowledge, this is the only manuscript that evaluated the use of a devise to assist the rescuers in performing CPR. This is a vital area of research since improving CPR in pediatric would rescue many lives.

Please find below some of the suggestions that would improve the quality of the manuscript.

Major suggestions or questions:

1. Why did it take the investigators a long time after the simulation (Oct and Nov 2016) to prepare the manuscript and submit it for publications? Many papers were published during this period on new finger location and numbers since then. (1-5) one of the new techniques has many publications showing its superiority to TFT.

- Thank you for your comment. I was able to finish the prospective study in a timely manner but due to personal health reasons, I was not able to finish writing the paper. Now that I have almost full recovered, I had the time to finally write it. I am aware that there were other papers published on new devices with a mannequin study, so I was deeply disappointed in my late publication. Thus, I would really love to have it published in your journal.

.

2. The authors used a random cross over method to test the different techniques. Also, they mentioned that some of the techniques caused fatigue more than the others. Did the authors check the effect of starting with a harder technique on the performance of participants in the other techniques?

Response: Thank you for your comment. We did not check the effect of starting with a harder technique because we purposely used a random order for the different chest compression techniques for each participant. Thus, we felt that starting with a harder technique was not necessary. Also, CPR was performed on the manikin for 2 minutes with each technique, followed by a 2-minute rest. This 2-minute rest time gave the participants ample time to recover from any fatigue.

3. Did the authors check the difference in the performance of the participants depending on their levels (doctors, residents and students)?

Response: Thank you for your comment. We did check the performance based upon their levels, but the data showed that it was not statistically significant. This point is already described in ‘Limitation’ session.

4. How were the CD, the compression rate, finger position, and the recoil recorded and evaluated? Does the manikin record them?

- Thank you for your comment. In the Study Design section of the Materials and Methods it is explained that a 3-month-old infant manikin (Resusci® Baby QCPR® by Laerdal Medical) was used and was fitted with a SimPad PLUS with Skill Reporter (Laerdal Medical). The chest compression performance data were collected using the SimPad Skill Reporter. For each technique, the total number of chest compressions (compression/min), CD (mm), and the percentages of correct CD, adequate compression rate, compression with correct finger position, and complete recoil of the chest were recorded. The analyzed comparison data among each different method groups are presented in Table 1.

5. Does the manikin record other parameters like simulated SBP, DBP, mean arterial pressure, and pulse pressure?

- Thank you for your comment. The manikin cannot record other parameters such as simulated SBP, DBP, mean arterial pressure, and pulse pressure. In the future, after the publication of this article, we plan to use an infant animal model to test the effectiveness of the new device and record other parameters.

6. Did the author account for the primary/dominant hand of the participant? In the text they mentioned that all the participants used their right hand fingers for the compressions. How many participants were left handed? How was the performance of these participants in comparison with the right handed ones?

- Thank you for your comment. Two of the participants were left-handed and were given the opportunity to use their dominant hand but both of them individually chose to use their right hand for chest compressions.

7. The authors should provide further description or details about the used device in the PAT technique.

a. Is it patented?

- The used device is not patented.

b. Is it commercially available? What company invented it?

- It is not commercially available. Three samples were made by the Department of Medical Engineering at Seoul National University as our request.

c. Is there any other device in the market or experimental to compare this device to it?

- There is no other device in the market or experimental to compare with this device.

8. Depending on the author responses to question 7, the conflict of interest of the group would be more clear to the reviewers and the journal.

- Thank you for your comment. We have added the above to the COI.

Minor

1. Spelling mistakes (line 2 Paediatric and line 4, pediatric).

- We made the spelling uniform.

2. On line 145, remove one of “That” after TFT.

- The word was removed.

3. The description of the dimensions of the circular piece (line 39) must report either the diameter or the radius and not 2 dimensions since it is circle shape. Please modify.

- We modified it to “a 1.0 cm in diameter…”

4. Authors must improve the appearance of Table 1. It is hard to get the results as it is now.

- The table has been modified.

5. The orientation of the manikin and the fingers position in figure 1 (PT1 and PT2) is not clear. I suggest a better orientation like the other images.

- Thank you for your comment. However, if we take pictures from another orientation, the position of thumb is not clearly visible so it is difficult to distinguish finger position.

6. I suggest that the authors move some of the graphs presented in the supplementary sections to the main manuscript body to enrich the article.

- Your suggestion has been noted. Among supplementary figures, two figures was moved as Fig 3.

7. The numbering of the figures in the supporting information file should start with 1, and the authors should assign a special character to reflect the location of the figure in the supplement file. The authors should check the guidelines of PLoS one for this issue.

- The numbering of the figures was adjusted according to the guidelines of PLoS one.

1. Ladny J, Smereka J, Rodriguez-Nunez A, Leung S, Ruetzler K, Szarpak L. Is there any alternative to standard chest compression techniques in infants? A randomized manikin trial of the new “2-thumb-fist” option. 2018. e9386 p.

2. Smereka J, Bielski K, Ladny J, Ruetzler K, Szarpak L. Evaluation of a newly developed infant chest compression technique A randomized crossover manikin trial 2017. e5915 p.

3. Smereka J, Szarpak L, Ladny J, Rodriguez-Nunez A, Ruetzler K. A Novel Method of Newborn Chest Compression: A Randomized Crossover Simulation Study 2018. 159 p.

4. Smereka J, Szarpak L, Rodriguez-Nunez A, Ladny J, Leung S, Ruetzler K. A randomized comparison of three chest compression techniques and associated hemodynamic effect during infant CPR: A randomized manikin study 2017. 1420-5 p.

5. Smereka J, Szarpak L, Smereka A, Leung S, Ruetzler K. 2017. Evaluation of new two-thumb chest compression technique for infant CPR performed by novice physicians. A randomized, crossover, manikin trial 604-9 p.

Reviewer #2: Dear authors,

Thank you for the opportunity to review the manuscript "Comparison of standard and alternative methods for chest compressions in a single rescuer infant CPR: a prospective simulation study".

A very interesting study concerning an important medical field that I have read with great interest.

I wish you all the best for publication.

Kind regards

________________________________________

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Reviewer #1: Yes: Moustafa Al Hariri

Reviewer #2: No

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Submitted filename: Response to Reviewers - revised.docx

Click here for additional data file.

31 Oct 2019

PONE-D-19-19476R1

Comparison of standard and alternative methods for chest compressions in a single rescuer infant CPR: a prospective simulation study

PLOS ONE

Dear Dr Kim,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

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Lars-Peter Kamolz, M.D., Ph.D., M.Sc.

Academic Editor

PLOS ONE

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #2: (No Response)

Reviewer #3: (No Response)

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #2: (No Response)

Reviewer #3: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: (No Response)

Reviewer #3: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #2: (No Response)

Reviewer #3: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #2: (No Response)

Reviewer #3: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #2: (No Response)

Reviewer #3: Dear authors,

I got to review your manuscript "Comparison of standard and alternative methods for chest compressions in a single rescuer infant CPR: a prospective simulation study", in which you show the superiority of a newly developed technique over the currently recommended ones. While in general, I think your manuscript is of great value and has gained a lot of value by the first revision, I would like to add a few minor points:

1.) Consider adding another figure about the currently recommended techniques (lines 8ff.) for the purpose of presentation.

2.) I would appreciate a little more context about your motivation, on WHY you performed this research. You mention, that you wanted to "overcome the insufficient CD of the TFT and alleviate discomfort", however, please elaborate a little bit more, especially considering the fact THAT and why other techniques seem to be insufficient.

3.)In line 51, you should mention that the 5-point Likert scale questionnaire was performed after EVERY one of the techniques. As it is written now, it appears that it was performed just ones at the very end (In line 118 you mention it correctly).

4.) In the measured outcomes section you write about all the outcomes, however, it remains unclear how "correct" is defined. in Data Collection you write about the correct finger position, but how correct (or adequate) compression rate, correct chest recoil and correct CD are defined, remains unclear. Please clarify.

5.) I would be very interested, whether the sequence yielded different results for the different techniques (e.g. has the TFT1 technique yielded better results when performed first...?) I am wondering, because I can imagine, that when performing five different techniques, the motivation reduces over time. Furthermore, it would be also very interesting how the "correctness" of each technique changed over the duration of the performance - can any statement concerning the recommended length before a change of rescucitator be given? How significant is the fatigueness during the performance?

6.) Please add a sentence to the limitations section that this experiment should also be repeated with a group of experienced doctors/health care practitioners (like paediatricians or emergency doctors) to evaluate the effectiveness in a group of other relevance.

Thank you.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #2: No

Reviewer #3: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files to be viewed.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email us at figures@plos.org. Please note that Supporting Information files do not need this step.

18 Nov 2019

Response to Reviewers

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #2: (No Response)

Reviewer #3: (No Response)

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #2: (No Response)

Reviewer #3: Yes

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: (No Response)

Reviewer #3: Yes

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #2: (No Response)

Reviewer #3: Yes

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #2: (No Response)

Reviewer #3: Yes

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #2: (No Response)

Reviewer #3: Dear authors,

I got to review your manuscript "Comparison of standard and alternative methods for chest compressions in a single rescuer infant CPR: a prospective simulation study", in which you show the superiority of a newly developed technique over the currently recommended ones. While in general, I think your manuscript is of great value and has gained a lot of value by the first revision, I would like to add a few minor points:

1.) Consider adding another figure about the currently recommended techniques (lines 8ff.) for the purpose of presentation.

Thank you for your comment. The currently recommended one rescuer compression technique by the ERC and AHA guidelines is the 2-finger technique (TFT). TFT is shown as the first image in Figure 1 (TFT1).

2.) I would appreciate a little more context about your motivation, on WHY you performed this research. You mention, that you wanted to "overcome the insufficient CD of the TFT and alleviate discomfort", however, please elaborate a little bit more, especially considering the fact THAT and why other techniques seem to be insufficient.

Thank you for your comment. The manuscript was adjusted as following:

We undertook this study due to TFT having insufficient CD and to alleviate discomfort in the user’s fingers after prolonged compressions. TTHT was reported to consistently achieve higher blood and coronary perfusion pressure and greater compression depth (CD) in a variety of animal and manikin models (7-11). However, most resuscitation guidelines recommend the TFT method for single-rescuer infant CPR because of the longer hands-off time and difficulty of postural change.

3.) In line 51, you should mention that the 5-point Likert scale questionnaire was performed after EVERY one of the techniques. As it is written now, it appears that it was performed just ones at the very end (In line 118 you mention it correctly).

Thank you for your comment. Line 51 was changed to the following:

At the end of each technique, the participants completed the 5-point Likert scale-based questionnaire.

4.) In the measured outcomes section you write about all the outcomes, however, it remains unclear how "correct" is defined. in Data Collection you write about the correct finger position, but how correct (or adequate) compression rate, correct chest recoil and correct CD are defined, remains unclear. Please clarify.

Thank you for your comment.

Lines 65 – 68 were adjusted to include the word “correct” as follows:

The correct finger position was specified as just below the nipple line in the middle of the chest in a 1.0 × 1.0 cm square. We defined correct CD as ≥ 40 mm, correct compression rate as 100–120/min, and complete recoil as the manikin’s chest returning to its original position.

5.) I would be very interested, whether the sequence yielded different results for the different techniques (e.g. has the TFT1 technique yielded better results when performed first...?) I am wondering, because I can imagine, that when performing five different techniques, the motivation reduces over time. Furthermore, it would be also very interesting how the "correctness" of each technique changed over the duration of the performance - can any statement concerning the recommended length before a change of rescucitator be given? How significant is the fatigueness during the performance?

Thank you for your comment. We did not check the effect of starting with a harder technique because we purposely used a random order for the different chest compression techniques for each participant. Thus, we felt that starting with a harder technique was not necessary. Also, chest compressions were performed on the manikin for 2 minutes with each technique, followed by a 2-minute rest. This 2-minute rest time gave the participants ample time to recover from any fatigue. A method of chest compression for 2-minute is widely recommended before changing the resuscitator.

6.) Please add a sentence to the limitations section that this experiment should also be repeated with a group of experienced doctors/health care practitioners (like paediatricians or emergency doctors) to evaluate the effectiveness in a group of other relevance.

Thank you for your comment. This sentence was added to the Limitations section:

Finally, for future studies to evaluate the effectiveness of the techniques, the participants should include experienced doctors and healthcare practitioners since the current study only included medical students and residents.

Thank you.

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #2: No

Reviewer #3: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files to be viewed.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email us at figures@plos.org. Please note that Supporting Information files do not need this step.

Submitted filename: Response to Reviewers (minor revision).docx

Click here for additional data file.

4 Dec 2019

Comparison of standard and alternative methods for chest compressions in a single rescuer infant CPR: a prospective simulation study

PONE-D-19-19476R2

Dear Dr. Kim,

We are pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it complies with all outstanding technical requirements.

Within one week, you will receive an e-mail containing information on the amendments required prior to publication. When all required modifications have been addressed, you will receive a formal acceptance letter and your manuscript will proceed to our production department and be scheduled for publication.

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With kind regards,

Lars-Peter Kamolz, M.D., Ph.D., M.Sc.

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #2: (No Response)

Reviewer #3: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #2: (No Response)

Reviewer #3: (No Response)

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: (No Response)

Reviewer #3: (No Response)

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #2: (No Response)

Reviewer #3: (No Response)

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #2: (No Response)

Reviewer #3: (No Response)

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #2: (No Response)

Reviewer #3: (No Response)

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

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Reviewer #2: No

Reviewer #3: No

11 Dec 2019

PONE-D-19-19476R2

Comparison of standard and alternative methods for chest compressions in a single rescuer infant CPR: a prospective simulation study

Dear Dr. Kim:

I am pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

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With kind regards,

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on behalf of

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PLOS ONE