Article

Effectiveness of finger-marker for maintaining the correct compression point during paediatric resuscitation: A simulation study

a b s t r a c t

Objective: high-quality cardiopulmonary resuscitation is a significant factor for increasing the survival rate of paediatric patients. This study is to investigate the effectiveness of finger-marker stickers for maintaining the cor- rect compression point during simulated infant cardiopulmonary resuscitation (CPR).

Methods: This crossover simulation study was conducted with 40 emergency physicians and paramedics at emer- gency departments of 2 tertiary hospitals. We used a remodeled infant CPR manikin developed to measure CPR quality indicators. After random coupling of participants (20 pairs), the pre-group (10 pairs) performed conven- tional 2-rescuer infant manikin CPR, then performed sticker-applied CPR after 1 month. The post-group (10 pairs) performed the process in the opposite order. The participants placed finger-marker stickers to indicate the appropriate compression point before starting CPR. We compared accurate finger placement rates and other CPR quality indicators (compression depth, rate, complete chest recoil, and hands-off time) with and with- out the finger-marker sticker.

Results: All finger-marker stickers were correctly attached within 5 s (4.88 +- 1.28 s) of approaching the model. There were significant differences in the rate of correct finger compression position between conventional and sticker-applied CPR (25.4% [IQRs 7.6-69.8] vs. 88.2% [IQRs 69.6-95.5], P b 0.001). Results did not differ according to sex, career, and job of the participants. There were no significant differences in mean compression rate, depth, hands-off times, and rate of fully recoiled compression between the 2 groups.

Conclusion: Finger-marker stickers can be used to maintain correct finger positioning during 2-rescuer infant manikin CPR.

(C) 2017

Introduction

The prevalence of out-of-hospital cardiac arrest for persons aged b 20 years is 4 to 8 per 100,000 children. Of those, infants show the highest cardiac arrest rate (up to 70 per 100,000). In addition, the sur- vival rates of cardiac arrest has been shown to be higher in children (varying from 2% to 12%) than in adults [1].

? Conflicts of interest and source of funding: The research plan was approved by the Seoul National University Hospital institutional review board (IRB NO: 1203-062-402) and the written consents were obtained from all participants. There are no conflicts of interests and currently no funding sources in this study.

* Corresponding author at: Department of Emergency Medicine, Seoul National University Hospital, 101 Daehak-Ro Jongno-Gu, Seoul 110-744, Republic of Korea.

E-mail addresses: [email protected] (Y.H. Kwak), [email protected] (H. Kwon), [email protected] (Y.J. Choi), [email protected] (D.K. Kim), [email protected]

(H.C. Kim), [email protected] (J.C. Lee), [email protected] (J.H. Park), [email protected] (H. Lim).

High-quality cardiopulmonary resuscitation (CPR) is strongly em- phasized and regarded as a significant factor for increasing the survival rate of the patients in the revised 2010 and 2015 American Heart Asso- ciation (AHA) and European Resuscitation Council (ERC) CPR guidelines [2]. High-quality CPR is composed of 5 key factors (compression rate, compression depth, chest recoil, compression interruption, and ventila- tion) [3]. In addition, the AHA and ERC guidelines recommend that fin- gers should be placed over the midsternum just below the midpoint of the inter-nipple line in infants. The correct positioning of the fingers (compression point) is preferred to avoid Possible complications of CPR. The complication rate post-CPR in children was reported as 7%, and the rate of serious internal organ injury, such as retroperitoneal haem- orrhage, pneumothorax, and pulmonary haemorrhage, was reported as 3% [4]. In adult CPR, it is well known that improper hand positioning

can cause complications such as rib fractures and cardiac injury [5-7]. A previous study using Simulation models has reported that, only

68% of the CPR-trained compressors performed adult CPR using correct

http://dx.doi.org/10.1016/j.ajem.2017.04.003

0735-6757/(C) 2017

hand positioning. The rate decreased to 59% in the 2 months after the last CPR training; this was similar to the rates for CPR performed by un- trained compressors [8]. Results of one simulation study using a mani- kin with a sticker attached to the compression point showed improved hand positioning and an increase in the proportion of correct use up to 97%. However, all of these studies were performed in an adult CPR setting. Studies specific to a paediatric CPR setting, particularly for CPR in infants, have not been done [9].

The objective of this study was to assess the effectiveness of marking to facilitate correct finger positioning (attachment of a finger-marking sticker) and hence to maintain correct compression point during infant CPR.

Methods

Study setting and population

This prospective crossover simulation study was conducted at two tertiary academic hospital from January 2013 to December 2015. The re- search plan was approved by the hospital institutional review board (IRB no: 1203-062-402). This study was based on healthy volunteers comprising 40 emergency physicians and emergency medical techni- cians who were certified as basic life support (BLS) providers or instruc- tors by AHA education programs. All participants received training according to the revised version of the 2010 AHA CPR guidelines and had no experience performing chest compressions on a manikin with a finger-marker sticker. Written consents were obtained from all participants.

Infant CPR manikin

In this study, we used an already remodeled infant CPR manikin. The Baby Anne manikin (Laerdal Medical, Stavanger, Norway) was remodeled according to 2005 AHA CPR guideline with the help from the Seoul National University College of Biomedical Engineering [10]. The remodeled infant manikin was fitted with augmented pressure-de- tection sensors for the location of compressions inside the manikin, and the sensors helped verify whether chest compressors maintained the correct hand position over the lower half of the sternum, just distal to the midpoint of the intra-nipple line. The pressure detecting sensor were 4 force sensitive resistance sensor located with diamond shape (top, bottom, left, and right). The sensing area of pressure was rectangu- lar shaped (width: 32 mm, height length: 14 mm) [10]. The sensors de- tected each compressed point by each finger movement and directly delivered the data to a computer via USB line. Four pressure sensors (right, left, top, and bottom) were used to determine finger positions at each compression [10]. By measuring intensity of the forces applied to each sensor the centroid value, Xc and Yc, was calculated based on the following equations.

right . 16 right -left . 16 left

both Xc and Yc are undetermined value, finger positions are outside of the sensing zone and such cases were excluded from the data process- ing. In this study, about 8% of total compression (1495 compressions of a total of 17,913 compressions) resulted in out of the sensing zone. With the remodeled manikin, we were able to collect data on compres- sion rate, compression depth, compression-to-depression ratio, hands- off times, and finger positioning (compression point). Finger placement was measured at each maximal compression pressure point and displayed on a computer monitor. Compression depth was measured until 35 mm because of the depth limitation of the manikin.

Finger-marker sticker

We used a 1 cm x 1.5 cm 8-figure-shaped sticker (finger-marker sticker) to indicate correct finger placement on the chest wall of the manikin. The 2010 AHA CPR guidelines recommended that fingers were placed on the middle of the lower one third of the sternum. How- ever, the sticker was inevitably placed at the point just below where the intra-nipple line and midline of the sternum coincide, because the al- ready developed manikin system [10] was made in accordance with the 2005 guideline.

Study protocol

All study subjects were given 15 min of dedicated instruction about the use of the finger-marker sticker before the sticker-used CPR simula- tion. For assessing correct sticker placement, another study investigator not participating in the data analyses assessed the accuracy of sticker placement. A N 0.5 cm deviation in any direction was regarded as incor- rect placement.

None of the participants knew the study objective, and they were assigned into 2 groups. Both the pre-group (N = 20) and post-group (N = 20) included 10 pairs. All simulated infant CPR was performed in a standard 2-rescuer protocol (compression-to-ventilation ratio = 15:2); 2 min for each pair to minimize the effect of rescuer fatigue. This crossover simulation study was conducted in 2 steps (Fig. 1). The pre-group performed 2 min of standard 2-rescuer infant CPR using two-thumb encircling technique without the finger-marker sticker first, and then 1 month later performed CPR with the finger-marker sticker for minimizing the memory effect. The post-group performed CPR in the opposite order of the pre-group. During the simulated CPR, correction of finger positioning through communication between the rescuers to change the compression points was prohibited.

Outcome measures

All simulated CPR data were displayed by specifically programmed software using the LabVIEW (National Instruments, Austin, TX, USA) front panel. The primary outcome was the difference of accurate finger placement proportion with or without sticker application. Accurate fin-

Xc =

rightmax

right + left

. .

leftmax

ger placement was indicated if the maximal pressure point was includ- ed in the predetermined 1 cm x 1.5 cm. We calculated the rate of

correct/incorrect finger position of each individual and compared the

Yc =

top . 8 5 top -bottom . 5 5 bottom topmax bottommax

top + bottom

values of the accuracy rates with and without a sticker. Secondary out- comes were the time in attaching the sticker to the manikin, rate and depth of chest compressions, the proportion of chest compressions with complete chest recoil (compression to decompression ratio), and

where, right, left, top, and bottom are the detected values from each sensor and rightmax, leftmax, topmax, and bottommax are the maximum values that are available from each sensor according to their individual datasheet. If either sum of right and left value or that of top and bottom value becomes zero, either Xc or Yc cannot be determined according to the above equations. Determined Xc with undetermined Yc means fin- ger positions are on the x-axis. Conversely, determined Yc with unde- termined Xc means finger positions are on the y-axis. However, if

hands-off time (duration of interruption of compression caused by com- pressor change and rescue breathing) in both groups (pre- and post- group). We also analyzed the distance from the center of the sensor (ideal point of compression) to the average of the maximal compression point of each participant for detecting the deviation of each compres- sion from ideal point (deviation distance). We also analyzed the accura- cy rate of finger positioning according to sex, career (standard: 3 years), and job.

Fig. 1. Study protocol.

Data analysis

Continuous variables were expressed as mean with standard devia- tion for normally distributed data or as medians with interquartile ranges (IQRs) for non-parametric data. Categorical variables were expressed as percentage frequency of occurrence. The proportion of cases with correct finger positioning was analyzed using the Wilcoxon Signed Rank Test. The compression rate and hands-off time between pre- and post-group were analyzed by Student t-test. The compression depth and compression to depression ratio between two groups were analyzed by Mann Whitney U test. Depth and hands-off time between the manikin with and without a sticker were analyzed by the paired t– test. On the other hand, the rate, compression to decompression ratio, and deviation distance between the manikin with and without sticker were analyzed by the Wilcoxon signed rank test. The data were ana- lyzed using State version 13.1 statistical software (State Corp. LP, Col- lege Station, TX, USA). We calculated the sample size, by referring to the previous similar adult simulation studies [9,11]. We assumed that the effect size was 0.42 and calculated the sample size as 37 when we set the alpha value as 0.05 and the power value as 0.8. Finally, the num- ber of all participants was calculated as 40 if we estimated the retract rate due to incorrect sticker position as 10%.

Results

A total of 40 subjects participated in this study: 20 emergency phy- sicians and 20 emergency medical technicians. Mean age was

28.8 years (SD 3.7) and male sex was 57.5%. All participants attached the finger-marker sticker accurately within approximately 5 s (4.88

+- 1.28 s). Table 1 shows the detailed demographics of participants

and characteristics of CPR performance with or without finger sticker application. All CPR performances, including compression duration, compression rate, compression depth, compression-to-decompression ratio, and hands-off time, were not different between the 2 scenarios. Table 2 indicates the characteristics of CPR performance and demo- graphics of participants between pre- and post-group. Fig. 2A shows the difference of accurate finger placement proportion of total partici- pants. The finger placement with the finger-marker sticker was more accurate than without the finger-marker sticker (conventional: 25.4% [IQRs 7.6-69.8] vs. sticker-applied: 88.2% [IQRs 69.6-95.5], P b 0.001). This result did not differ according to sex (Fig. 2B), job (emergency phy- sicians vs. emergency medical technicians, Fig. 2C), and career (N 3 years vs. b 3 years, Fig. 2D). The accuracy of correct finger positioning in- creased according to all items (sex, job, and career) after sticker applica- tion. The accuracy of finger positioning before sticker application was

Table 1

A total of participants’ demographics and performance.

Total Conventional compression Sticker-A compression P

Age, years, mean (SD) 28.8 (3.7)

Sex, male (%) 23 (57%)

Performance

Compression rate/min, mean (SD) 123.1 (1.8) 123.4 (2.2) 122.8 (1.7) 0.74

Compression depth (mm), median, IQR 34.3 (33.2-35.0) 34.2 (33.3-35.0) 34.2 (33.0-35.0) 0.57

Compression to depression ratio, median, IQR 1.0 (1.0-1.0) 1.0 (1.0-1.0) 1.0 (1.0-1.0) 0.13

Hands-off time (s), mean (SD) 4.2 (0.4) 4.1 (0.6) 4.2 (0.6) 0.42

Sticker-A = sticker applied; SD = standard deviation; IQR = interquartile range.

Table 2

Participants’ demographics and performance of pre- and post-group.

shorter than without the finger-marker sticker (conventional: 5.3 mm [IQRs 5.2-5.6 mm] vs. sticker-applied: 2.2 mm [IQRs 2.1-3.9 mm], P b

Performance

Compression rate/min, mean (SD)

122.7 (13.4)

123.4 (9.4)

0.85

Compression depth (mm), median, (IQR)

34.3

34.3

0.66

(32.3-34.9)

(33.4-34.9)

Compression to depression ratio,

1.0 (1.0-1.0)

1.0 (1.0-1.0)

0.43

median, (IQR)

Hands-off time (s), mean (SD)

4.2 (0.3)

4.1 (0.5)

0.82

Total accuracy rate (%), median, (IQR)

56.0

56.7

0.76

(46.5-78.3)

(37.9-76.5)

Pre-group = without sticker first; Post-group = with sticker first; N = number; SD = standard deviation; IQR = interquartile range.

different between emergency physicians and emergency medical tech- nicians (19.6% vs. 42.3%, P = 0.036), and there was no difference of ac- curacy after sticker application between emergency physicians and emergency medical technicians (84.2% vs. 94.0%, P = 0.052) (Table 3). The accuracy rate of finger position in pre-group were 35.4% (IQRs 9.4-73.0%, without sticker) and 87.9% (IQRs 65.7-95.4%, with sticker) (P b 0.001). Also, the correct finger positioning rate of post-group were 22.7% (IQRs 5.6-59.2%, without sticker) and 89.0% (IQRs 70.0- 95.8%, with sticker) (P b 0.001). Most missed compressions were locat- ed in the right lower area compared with appropriate compression ranges and the deviation distance with the finger-marker sticker was

The current CPR guidelines emphasize on high-quality CPR. Chest compressions in CPR play a critical role in the return of spontaneous cir- culation through artificial circulation and increased blood flow. For effi- cient chest compressions in CPR, 5 key factors are emphasized. Unfortunately, correct hand or finger positioning was not considered key factor.

Pre-group

Post-group

P

0.001) (Fig. 3).

N

Age, years, mean (SD)

20

29.3 (4.2)

20

28.3 (3.1)

0.43

4. Discussion

Sex, male (%)

10 (50%)

13 (65%)

0.43

Correct chest compression at the recommended site is important, but there are no studies that assess the role of correct finger positioning for site-location in infant CPR. We report for the first time the use of manikin in an infant CPR setting. Our results suggest a 43.8% rise in the rate of correct finger positioning after the sticker application while maintaining other CPR performance variables, including compression depth, compression rate, and hands-off time. The time taken for apply- ing the sticker was not N 5 s for all participants and hence it did not in- terrupt the infant CPR process.

A previous simulation study based on an adult CPR setting, showed that the correct positioning of the hand increased by 12% when using an assistive hand-positioning device [9]. In yet another simulation study for adult CPR, it was suggested that unfamiliar rescuers did not compress at the correct location, and even after being provided the training for the locating the correct chest compression site, the rate of correct hand positioning was not high and decreased considerably

Fig. 2. Finger position accuracy rate. There was a significant increase of the accurate finger positioning rate after sticker application (A). Increased accurate finger positioning rates did not differ according to sex (B), job (C), and career (D, standard: 3 years). There was a significant difference of correct finger positioning rate between emergency physicians (EPs) and emergency medical technicians in conventional compression during infant manikin cardiopulmonary resuscitation (D). **P b 0.001; *P b 0.05.

Table 3

Accurate rate of finger position according to sex, career and job.

Sex

Career

Job

Male

Female

N 3 years

b 3 years

EPs

EMTs

Number

23

17

27

13

20

20

Median accuracy

Conventional compression (%)

24.3

26.5

26.5

13.2

19.6?

42.3?

IQRs (%)

7.9-60.4

6.7-81.7

13.7-71.5

3.7-66.7

5.5-48.4

13.8-84.8

Sticker-applied compression (%)

86.2

92.9

91.2

75.7

84.2

94.0

IQRs (%)

64.1-94.2

69.9-96.5

69.3-96.0

67.6-93.4

60.9-92.4

71.7-96.7

EPs = emergency physicians; EMTs = emergency medical technicians; IQRs = interquartile ranges.

* P b 0.05.

over time [11,12-13]. These results indicate that unfamiliar rescuers may have difficulty in locating the site or maintaining the correct hand positioning. Because cases of infant CPR are rare, most infant CPR rescuers have little experience, and hence incorrect finger positioning may be frequent. Based on our findings, we anticipate that the use of a finger-marker sticker for infant chest compression will result in a more efficient infant CPR.

Studies demonstrate that some CPR chest compression complica- tions can have serious outcomes [2-3,14], and chest compression below the recommended site for infant CPR can cause compression of the upper abdomen to about 25% [15] and liver injury. We suggest that the use of the finger-marker sticker at the compression site will help to prevent such injuries.

In this study, the change in the rate of correct finger positioning be- fore and after the sticker application did not differ according to sex, ca- reer, and job; however, there were significant differences in the accuracy rate before sticker application. Before the sticker application, the emergency medical technicians performed better in terms of correct finger positioning than the emergency physicians. Such result may re- flect our institutional policies. At our institution, when patients requir- ing CPR arrived at the paediatric emergency department, most compressions were conducted by the emergency medical technicians.

Moreover, most missed compressions were located at the lower- right area when compared to the correct compression site suggested in this study. In addition, all study participants were right-handed. This implies that right-handed individuals can apply more pressure with their right thumb during chest compressions despite the guidance such as a finger-marker sticker. Hence, future studies based on CPR as- sistive devices that consider equal strength on both thumbs on finger sticker are required.

The present study demonstrated that compression with sticker sig- nificantly decreased the deviation distance compared to the compres- sion without sticker (difference 3.1 mm, P b 0.001). Although the deviation was significantly decreased, the effect of 3.1 mm reduction may be uncertain in real clinical settings.

In all pre- and post-studies, there was always the possibility of a re- sidual memory effect. Therefore, in most studies, the time interval of a certain periods is set to minimize the memory effect. In our study, we set a period of one month. As shown in Table 2, we thought that this re- sidual memory effect was minimized because there was no difference in the CPR parameters between the pre-group and the post-group.

There are several limitations in this study. Firstly, this study was a simulation study using infant manikins and so did not reflect real infant emergencies. Although, the compression with the sticker increased the accuracy of the finger position and resulted in the compression of a sim- ilar area to the actual compression point in infant manikin CPR, it may be different in actual CPR situations. Also, in real CPR situations, rescuers will spend more or less time on sticker application. To overcome this limitation, further studies on real infant CPR cases are required. Second- ly, all study participants were certified in and were good at BLS. Al- though they were not aware of the study objective, there is a possibility that they already knew the importance of the chest compres- sion site. However, we think that there is little chance of that because current BLS education does not emphasize on hand positioning during chest compressions. Thirdly, all study participants attached the finger- marker stickers at the appropriate site within 5 s. However, no lay res- cuers were targeted in this study. Generalization of results hence re- quires further supporting studies. Fourth, in this study, finger position was set just below inter-nipple line in CPR guideline different from 2010 CPR guideline, because of the limitation of developed manikin. If

Fig. 3. Distribution of all compression points between conventional compression (A) and sticker-applied compression (B). The black-lined rectangular box was the area of pressure sensor. The inside of the 8-figure shape was the correct compression site (red dots) and the outside was incorrect (green dots). Mean of all compressions was expressed *.

the position of the fingers is lower one third of the sternum according to the guideline of 2010, different results may be obtained. However, we do not think that changing the sticker position will have a large impact on the results and further study will be needed. Lastly, CPR duration in this study was relatively short (about 2 min); therefore, the effect of longer CPR duration was not reflected in this study.

5. Conclusion

The identification of the chest compression site using a finger-mark- er sticker was useful in maintaining correct finger position during 2-res- cuer infant manikin CPR, and the finger-marker sticker might help in preventing internal organ injury.

Conflicts of interest

There are no conflicts of interest.

Financial relationships

None declared.

Acknowledgements

The authors wish to thank the emergency physicians and emergency medical technicians for participating in the study.

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