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Emergency Medicine Australasia (2015) 27, 108–112
doi: 10.1111/1742-6723.12364
ORIGINAL RESEARCH
Should we change chest compression providers every 2 min when performing one-handed chest compressions? Je Hyeok OH, Sung Eun KIM, Chan Woong KIM and Dong Hoon LEE Department of Emergency Medicine, College of Medicine, Chung-Ang University, Seoul, Korea
Abstract Objective: Because the one-handed chest compression (OHCC) technique uses one hand, unlike the two-handed chest compression (THCC) technique, compression depth might be reduced more rapidly in OHCC than THCC. The present study was conducted to determine whether compression depth was affected within 2 min after the start of OHCC in a simulated inhospital paediatric arrest model. Methods: Forty medical doctors performed continuous OHCC on a child manikin lying on a hard floor using a CPRmeter for 2 min. The hand used to perform the OHCC technique was randomised to the right or left hand. The mean compression depth (MCD) and the mean compression rate (MCR) were calculated at 30 s intervals using the Q-CPR review software. Results: MCD values decreased significantly with time (0–30 s: 44.3 ± 4.1 mm, 30–60 s: 42.4 ± 4.9 mm, 60– 90 s: 40.5 ± 5.8 mm, and 90–120 s: 38.7 ± 5.7 mm; P < 0.001). The MCR also tended to decrease with time (0– 30 s: 119.3 ± 12.5/min, 30–60 s: 119.0 ± 13.1/min, 60–90 s: 117.9 ± 14.5/ min, 90–120 s: 117.8 ± 14.9/min), and the differences were statistically significant between 30–60 s and 60–90 s (P = 0.037) and between 30– 60 s and 90–120 s (P = 0.043).
Conclusions: Compression depth was decreased significantly from 30 s onwards after starting the OHCC technique using a simulated paediatric arrest model. The results of the present study suggest that future strategies should be established to prevent a decrease in compression depth within 1 min during OHCC. Key words: cardiac arrest, cardiopulmonary resuscitation, child, fatigue.
Introduction The 2010 European Resuscitation Council (ERC) guidelines recommend that the chest compression provider should be switched every 2 min to maintain chest compression quality.1 Previous simulation studies using a manikin have shown that chest compression quality declines over time.2–4 Sugerman et al. 5 reported that compression depth was reduced significantly from 90 s onwards after starting cardiopulmonary resuscitation (CPR) during actual in-hospital resuscitation. However, these studies were conducted with adult manikins or adult patients with cardiac arrest using a two-handed chest compression (THCC) technique. Thus, the switching of rescuers was not mentioned in the paediatric life support section of
Correspondence: Professor Sung Eun Kim, Department of Emergency Medicine, College of Medicine, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 156-756, Korea. Email: [email protected] Je Hyeok Oh, MD, Clinical Assistant Professor; Sung Eun Kim, MD, PhD, Associate Professor; Chan Woong Kim, MD, PhD, Professor; Dong Hoon Lee, MD, PhD, Assistant Professor. Accepted 8 January 2015
Key findings • Compression depth was decreased significantly from 30 s onwards after starting the onehanded chest compression (OHCC) technique. • Switching of chest compression provider every 2 min was not appropriate in performing OHCC. • Future strategies should be established to prevent a decrease in compression depth within 1 min during OHCC.
the 2010 ERC guidelines. 6 It is unknown whether the 2 min switching of chest compression providers recommended in adult CPR should be applied to child CPR. Badaki-Makun et al.7 confirmed that 10 min of continuous chest compression on child and adult manikins resulted in decreased compression depth and increased compression rate. They provided evidence that the THCC technique in children also requires a 2 min switch of rescuers, as in adults. So, is this true for the one-handed chest compression (OHCC) technique? The OHCC technique can be used at the discretion of the physician, especially in children aged ≥1 year whose stature is relatively small (Table 1).6 Because the OHCC technique is performed with one hand, it is thought that rescuer fatigue could be induced even more rapidly by the OHCC technique than the THCC technique. Thus, the present study was conducted to determine whether compression depth changed within 2 min after the start of OHCC in a simulated in-hospital paediatric arrest model.
© 2015 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine
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FATIGUE EFFECT ON ONE-HANDED CHEST COMPRESSION
TABLE 1. Current recommendations on the compression techniques in paediatric population Number of rescuers Single rescuers Two or more rescuers
Infant
Child
Two-finger compression technique Two-thumb encircling technique
One- or two-hand technique† Same as above
†According to rescuer preference.
Medical doctors working in our hospital were enrolled in the present study. Participants completed the Basic Life Support provider course of the American Heart Association within 2 years and had clinical experience of less than 1 year. The sample size was calculated based on chest compression depth as the primary outcome variable. We set the two-sided significance level at 0.05 and the power of the test as 80%. The mean compression depth and standard deviation of compression depth was determined to be 41.3 ± 5.6 mm from the previous study.8 Under the hypothesis that the compression depth could decrease by 10% during a 2 min period, the allowable difference was set at 4.13 mm. Using a web program (sample size calculator: one sample mean) the minimum number of participants was determined to be 15.9
with the dominant and non-dominant hands,8 we should assign the participant’s hand, which will perform chest compression because only one hand is used in performing OHCC. The hands were assigned by a randomisation list arranged by random number sequences from web-based computer software using six permuted blocks (1. AABB, 2. ABAB, 3. ABBA, 4. BBAA, 5. BABA, 6. BAAB). The participants assigned to the letter of ‘A’ performed OHCC with the right hand and to the letter of ‘B’ performed OHCC with the left hand. The randomisation list was created before the experiment by the chief of the research. The researchers supervising data collection instructed participants which hand to perform OHCC. The participants were concealed about the allocation of hand and they used only the assigned hand during OHCC. Considering that the height of a hospital bed and the height of the participant’s knee might influence the compression depth, the manikin was placed in the supine position on a hard floor.10 To prevent participants from receiving feedback, the CPRmeter display was hidden. Audiovisual feedback to control the chest compression rate was not provided, because it could affect the chest compression depth.11
Study protocol
Outcome variables
The participants performed continuous OHCC for 2 min without ventilation using a simulated in-hospital paediatric arrest model, which included a Resusci Junior Basic and Skill Guide paediatric manikin (Laerdal Medical, Stavanger, Norway) and a CPRmeter (Laerdal Medical). Although it was reported that there was no significant difference in chest compression depth between OHCC
The mean compression depth (MCD) and the mean compression rate (MCR) collected by the CPRmeter were used as outcome variables. Data were calculated at 30 s intervals using the Q-CPR review program (ver. 3.1; Laerdal Medical).
Materials and methods The experiment consisted of single 2 min OHCC and performed at a university hospital. The present study was approved by the Institutional Review Board of our hospital (approval number C2014217(1414)).
Study population
Statistical analysis All statistical analyses were performed using the PASW statistics software (ver.
18.0; SPSS, Inc., Chicago, IL, USA). Data are presented as means ± SDs. The normality of the distribution of MCD and MCR data were analysed using a Shapiro–Wilk test. Normally distributed data were analysed using the two-sided paired t-test; otherwise, the Wilcoxon signed-rank test was used for statistical comparisons between the results of each 30 s interval. The Mann–Whitney U-test was used for statistical comparisons between the results of male and female and between the results of the right and left hand that performed OHCC. A P-value of < 0.05 was considered to indicate statistical significance.
Results Forty doctors (32 male, eight female), with a mean age of 26 ± 2.4 years, took part in the study. Twenty doctors performed OHCC with the right hand and twenty doctors with the left hand. The MCD values decreased significantly with time (Tables 2,3; Fig. 1). The MCR also tended to decrease with time, but the differences were statistically significant only between 30– 60 s and 60–90 s and between 30– 60 s and 90–120 s (Fig. 2). The MCD and MCR of the male participants were higher than the female participants, but the differences were statistically significant only in the MCR of the 30–60 s interval because the numbers of the female participants was small (Table 4). Comparisons of the MCD and MCR between the hands that performed OHCC were not different significantly (Table 5).
Discussion Previous studies have reported that long-term chest compression using adult manikins or adult patients might induce rescuer fatigue.2–5 However, previous simulation studies using child manikins have focused on chest compression technique rather than rescuer fatigue.12–14 Peska et al.13 documented that in 1 min paediatric CPR, the compression rate declined more rapidly with the OHCC technique than the THCC technique. Udassi et al. 14 demonstrated that compression depth, compression pressure and
© 2015 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine
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JH OH ET AL.
TABLE 2.
The mean compression depths and mean compression rates during a 2 min period
MCD (mm) MCR (/min)
0–30 s
30–60 s
60–90 s
90–120 s
44.3 ± 4.1 119.3 ± 12.5
42.4 ± 4.9 119.0 ± 12.5
40.5 ± 5.8 117.9 ± 14.5
38.7 ± 5.7 117.8 ± 14.9
MCD, mean compression depth; MCR, mean compression rate.
TABLE 3.
The statistical comparisons between the results of each 30 s interval
Statistical comparisons MCD MCR
0–30 s versus 30–60 s
0–30 s versus 60–90 s
0–30 s versus 90–120 s
30–60 s versus 60–90 s
30–60 s versus 90–120 s
60–90 s versus 90–120 s
0.000 0.711
0.000 0.200
0.000 0.192
0.000 0.037
0.000 0.043
0.000 0.758
MCD, mean compression depth; MCR, mean compression rate. A P-value < 0.05 is presented in bold.
Figure 1.
Box plot of the mean compression depth during a 2 min period.
compression rate decreased over time in a 5 min paediatric CPR with both the OHCC and THCC techniques, but they did not report the time points that showed definite decreases. In 2013, Badaki-Makun et al.7 reported that experimental results obtained from longterm paediatric CPR were similar to those obtained from long-term adult CPR, but they did not describe the results of the OHCC technique. The OHCC technique is different from the THCC technique with several reasons. First, we can use only one hand when performing chest compres-
sions. In contrast, both hands with the fingers interlocked can be used when performing THCC. Second, the axis transmit power to the victim’s chest is not located in the centre of the rescuers. As a result the rescuer might not load their full weight onto their hand. Therefore more muscles might be used when performing OHCC. It might reasonably be expected that rescuer fatigue would be induced more rapidly by the OHCC technique than the THCC technique simply because the OHCC technique might need greater muscle effort.
In addition we note that chest compression quality was reduced abruptly after 1 min of CPR using adult manikins.2–4 Those studies compared percentages of correct chest compression, not MCD values. If there were any conditions that did not satisfy the manikin settings for ‘correct’ compression, the chest compression would be counted as a false compression even if sufficient depth was provided. Thus, they might have overestimated rescuer fatigue. In fact, Sugerman et al.5 indicated that in adult-patient CPR using a Q-CPR device, compression depth decreased more slowly after 90 s. We considered that if compression depth was measured using an accelerometer device, such as a CPRmeter, instead of the depth-measuring device of the manikin itself, compression depth could be determined more accurately. Thus, we measured compression data with a CPRmeter and calculated the MCD and MCR at 30 s intervals. The MCD values did decrease significantly after 30 s. The MCR values did not show a significant difference within 1 min, but decreased significantly thereafter. In contrast, Badaki-Makun et al.7 reported that MCR values increased over time. One reason for this difference might be that participants in our study performed chest compressions at a rate of ∼120 min−1 although the 2010 ERC guidelines recommend that the compression rate should be at least 100 min −1 but not greater than
© 2015 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine
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FATIGUE EFFECT ON ONE-HANDED CHEST COMPRESSION
Figure 2.
Box plot of the mean compression rates during a 2 min period.
TABLE 4.
Comparisons according to the sex of the participants Male (n = 32)
Time MCD (mm) MCR (/min) Time MCD (mm) MCR (/min) Time MCD (mm) MCR (/min) Time MCD (mm) MCR (/min)
44.8 ± 4.1 121.3 ± 11.8 42.9 ± 4.9 121.4 ± 12.6 41.1 ± 5.7 120.1 ± 14.0 39.5 ± 5.8 120.2 ± 14.2
Female (n = 8) 0–30 s 42.4 ± 3.7 111.1 ± 12.7 30–60 s 40.4 ± 4.9 109.5 ± 11.2 60–90 s 38.0 ± 5.7 108.9 ± 13.5 90–120 s 35.6 ± 4.5 108.1 ± 14.8
P-value 0.082 0.065 0.134 0.020 0.134 0.065 0.055 0.065
MCD, mean compression depth; MCR, mean compression rate. A P-value < 0.05 is presented in bold.
120 min−1. The MCR values in BadakiMakun et al.’s study increased from 106 min−1 to 117.5 min−1 slowly over 10 min. Another reason might be that participants in our study were aware of the test period (2 min) before the test. Thus, they might have performed chest compressions at their maximum speed. However, because OHCC was performed for only 2 min in our study, the effects of rescuer fatigue on the compression rate were difficult to determine. The decrease of the compression depth during 2 min in our study was
only 5.6 mm. The 5.6 mm is a small value but it exceeds 10% of the recommended compression depth of the paediatric CPR.6 The guideline emphasised on achieving an adequate depth of compression; at least 1/3 of the anterior–posterior chest diameter in all children (i.e. approximately 5 cm in children).6 The recent studies supported that increased compression depths were associated with better survival compared with shallower compression depths in both adults and paediatric populations.15,16 Therefore the maintenance of
chest compression depth is important even if it is a small value. Based on our results, strategies for effective OHCC require the following considerations to maintain constant chest compression quality. First, compression depth can be maintained by converting the OHCC technique into the THCC technique within 1 min. Second, because there is apparently no significant difference in the chest compression quality of OHCC using the dominant versus nondominant hand,8 chest compression quality can be maintained by using the other hand within 1 min. Third, to maintain chest compression quality, paediatric CPR using the OHCC technique can be performed by changing the rescuer within 1 min. Because these considerations were based on our experimental results, further simulation studies are needed to confirm them. Additionally, it is worth considering that frequent changes of the hand or the rescuer might prolong the interruption times in chest compression. The results of the present study are subject to several limitations. First, because this was a simulation study, the results might not be applicable to the clinical situation. Second, because we used a simulated in-hospital paediatric arrest model, continuous OHCC was performed without ventilation. Thus, different results may be obtained in an out-of-hospital setting or in conditions without application of advanced airway. We performed CPR on a manikin on the floor, not on a bed, to exclude the difference in position between the manikin and the rescuer, which is not the same as the real-life in-hospital arrest situation. Third, although compression depth decreased significantly after 30 s, it did not reach the 5 cm during all intervals that is recommended by current guidelines for paediatric CPR. This might have been because the participants in our study were relatively novice rescuers, although they were healthcare providers who took their medical doctor licensure within 1 year. Other reasons might include the high compression rate and the manikin’s characteristics. Another study using the same manikin also reported chest compression depths below 5 cm.7 Finally,
© 2015 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine
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TABLE 5. Comparisons according to the performing hand of the participants Right hand (n = 20) Time MCD (mm) MCR (/min) Time MCD (mm) MCR (/min) Time MCD (mm) MCR (/min) Time MCD (mm) MCR (/min)
44.4 ± 4.6 115.6 ± 11.2 42.0 ± 5.1 115.3 ± 11.3 39.8 ± 6.1 113.6 ± 12.5 38.0 ± 6.2 113.0 ± 13.3
Left hand (n = 20) 0–30 s 44.2 ± 3.6 123.3 ± 12.9 30–60 s 42.9 ± 4.8 123.1 ± 14.1 60–90 s 41.3 ± 5.4 122.6 ± 15.3 90–120 s 39.5 ± 5.2 123.1 ± 15.1
P-value
7.
0.789 0.078 8. 0.668 0.130 0.611 0.093 0.630 0.061
9.
MCD, mean compression depth; MCR, mean compression rate.
10.
because CPR was performed for 2 min, the effects of rescuer fatigue on MCR might not have been determined fully. Further studies on this issue are warranted.
Conclusions Compression depth decreased significantly after 30 s during continuous OHCC using a simulated paediatric arrest model. The results of the present study suggest that future strategies for child victims should be established to prevent a decrease in compression depth within 1 min during performance of the OHCC technique.
Acknowledgement We thank all participants for their contribution in the present study.
Author contributions JHO was responsible for the conception and design of the study. CWK, SEK and DHL were responsible for the acquisition of data. JHO was responsible for analysis and interpretation of data. JHO, CWK and SEK were responsible for drafting the article or revising it critically for important intellectual content. SEK was responsible for the final approval of the version to be submitted.
Competing interests None declared. 11.
References 1. Koster RW, Baubin MA, Bossaert LL et al. European Resuscitation Council Guidelines for Resuscitation 2010 Section 2. Adult basic life support and use of automated external defibrillators. Resuscitation 2010; 81: 1277– 92. 2. Hightower D, Thomas SH, Stone CK, Dunn K, March JA. Decay in quality of closed-chest compressions over time. Ann. Emerg. Med. 1995; 26: 300–3. 3. Ochoa FJ, Ramalle-Gomara E, Lisa V, Saralequi I. The effect of rescuer fatigue on the quality of chest compressions. Resuscitation 1998; 37: 149–52. 4. Ashton A, McCluskey A, Gwinnutt CL, Keenan AM. Effect of rescuer fatigue on performance of continuous external chest compressions over 3 min. Resuscitation 2002; 55: 151– 5. 5. Sugerman NT, Edelson DP, Leary M et al. Rescuer fatigue during actual inhospital cardiopulmonary resuscitation with audiovisual feedback: a prospective multicenter study. Resuscitation 2009; 80: 981–4. 6. Biarent D, Bingham R, Eich C et al. European Resuscitation Guidelines for Resuscitation 2010 Section 6.
12.
13.
14.
15.
16.
Paediatric life support. Resuscitation 2010; 81: 1364–88. Badaki-Makun O, Nadel F, Donoghue A et al. Chest compression quality over time in pediatric resuscitations. Pediatrics 2013; 131: e797–804. Oh JH, Kim CW, Kim SE, Lee DH, Lee SJ. One-handed chest compression technique for paediatric cardiopulmonary resuscitation: dominant versus non-dominant hand. Emerg. Med. J. 2014; doi: 10.1136/emermed2014-203932. Centre for Clinical Research and Biostatistics. Sample size estimation. [Cited 1 Sep 2014.] Available from URL: http://www.cct.cuhk .edu.hk/stat/index.htm Cho J, Oh JH, Park YS, Park IC, Chung SP. Effects of bed height on the performance of chest compressions. Emerg. Med. J. 2009; 26: 807– 10. Oh JH, Lee SJ, Kim SE, Lee KJ, Choe JW, Kim CW. Effects of audio tone guidance on performance of CPR in simulated cardiac arrest with an advanced airway. Resuscitation 2008; 79: 273–7. Stevenson AG, McGowan J, Evans AL, Graham CA. CPR for children: one hand or two? Resuscitation 2005; 64: 205–8. Peska E, Kell AM, Kerr D, Green D. One-handed versus two-handed chest compressions in paediatric cardiopulmonary resuscitation. Resuscitation 2006; 71: 65–9. Udassi JP, Udassi S, Theriaque DW, Shuster JJ, Zaritsky AL, Haque IU. Effect of alternative chest compression techniques in infant and child on rescuer performance. Pediatr. Crit. Care Med. 2009; 10: 328–33. Sutton RM, French B, Niles DE et al. 2010 American Heart Association recommended compression depths during pediatric in-hospital resuscitations are associated with survival. Resuscitation 2014; 85: 1179–84. Stiell IG, Brown SP, Nichol G et al. What is the optimal chest compression depth during out-of-hospital cardiac arrest resuscitation of adult patients? Circulation 2014; 130: 1962–70.
© 2015 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine
Emergency Medicine Australasia (2015) 27, 108–112
doi: 10.1111/1742-6723.12364
ORIGINAL RESEARCH
Should we change chest compression providers every 2 min when performing one-handed chest compressions? Je Hyeok OH, Sung Eun KIM, Chan Woong KIM and Dong Hoon LEE Department of Emergency Medicine, College of Medicine, Chung-Ang University, Seoul, Korea
Abstract Objective: Because the one-handed chest compression (OHCC) technique uses one hand, unlike the two-handed chest compression (THCC) technique, compression depth might be reduced more rapidly in OHCC than THCC. The present study was conducted to determine whether compression depth was affected within 2 min after the start of OHCC in a simulated inhospital paediatric arrest model. Methods: Forty medical doctors performed continuous OHCC on a child manikin lying on a hard floor using a CPRmeter for 2 min. The hand used to perform the OHCC technique was randomised to the right or left hand. The mean compression depth (MCD) and the mean compression rate (MCR) were calculated at 30 s intervals using the Q-CPR review software. Results: MCD values decreased significantly with time (0–30 s: 44.3 ± 4.1 mm, 30–60 s: 42.4 ± 4.9 mm, 60– 90 s: 40.5 ± 5.8 mm, and 90–120 s: 38.7 ± 5.7 mm; P < 0.001). The MCR also tended to decrease with time (0– 30 s: 119.3 ± 12.5/min, 30–60 s: 119.0 ± 13.1/min, 60–90 s: 117.9 ± 14.5/ min, 90–120 s: 117.8 ± 14.9/min), and the differences were statistically significant between 30–60 s and 60–90 s (P = 0.037) and between 30– 60 s and 90–120 s (P = 0.043).
Conclusions: Compression depth was decreased significantly from 30 s onwards after starting the OHCC technique using a simulated paediatric arrest model. The results of the present study suggest that future strategies should be established to prevent a decrease in compression depth within 1 min during OHCC. Key words: cardiac arrest, cardiopulmonary resuscitation, child, fatigue.
Introduction The 2010 European Resuscitation Council (ERC) guidelines recommend that the chest compression provider should be switched every 2 min to maintain chest compression quality.1 Previous simulation studies using a manikin have shown that chest compression quality declines over time.2–4 Sugerman et al. 5 reported that compression depth was reduced significantly from 90 s onwards after starting cardiopulmonary resuscitation (CPR) during actual in-hospital resuscitation. However, these studies were conducted with adult manikins or adult patients with cardiac arrest using a two-handed chest compression (THCC) technique. Thus, the switching of rescuers was not mentioned in the paediatric life support section of
Correspondence: Professor Sung Eun Kim, Department of Emergency Medicine, College of Medicine, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 156-756, Korea. Email: [email protected] Je Hyeok Oh, MD, Clinical Assistant Professor; Sung Eun Kim, MD, PhD, Associate Professor; Chan Woong Kim, MD, PhD, Professor; Dong Hoon Lee, MD, PhD, Assistant Professor. Accepted 8 January 2015
Key findings • Compression depth was decreased significantly from 30 s onwards after starting the onehanded chest compression (OHCC) technique. • Switching of chest compression provider every 2 min was not appropriate in performing OHCC. • Future strategies should be established to prevent a decrease in compression depth within 1 min during OHCC.
the 2010 ERC guidelines. 6 It is unknown whether the 2 min switching of chest compression providers recommended in adult CPR should be applied to child CPR. Badaki-Makun et al.7 confirmed that 10 min of continuous chest compression on child and adult manikins resulted in decreased compression depth and increased compression rate. They provided evidence that the THCC technique in children also requires a 2 min switch of rescuers, as in adults. So, is this true for the one-handed chest compression (OHCC) technique? The OHCC technique can be used at the discretion of the physician, especially in children aged ≥1 year whose stature is relatively small (Table 1).6 Because the OHCC technique is performed with one hand, it is thought that rescuer fatigue could be induced even more rapidly by the OHCC technique than the THCC technique. Thus, the present study was conducted to determine whether compression depth changed within 2 min after the start of OHCC in a simulated in-hospital paediatric arrest model.
© 2015 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine
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FATIGUE EFFECT ON ONE-HANDED CHEST COMPRESSION
TABLE 1. Current recommendations on the compression techniques in paediatric population Number of rescuers Single rescuers Two or more rescuers
Infant
Child
Two-finger compression technique Two-thumb encircling technique
One- or two-hand technique† Same as above
†According to rescuer preference.
Medical doctors working in our hospital were enrolled in the present study. Participants completed the Basic Life Support provider course of the American Heart Association within 2 years and had clinical experience of less than 1 year. The sample size was calculated based on chest compression depth as the primary outcome variable. We set the two-sided significance level at 0.05 and the power of the test as 80%. The mean compression depth and standard deviation of compression depth was determined to be 41.3 ± 5.6 mm from the previous study.8 Under the hypothesis that the compression depth could decrease by 10% during a 2 min period, the allowable difference was set at 4.13 mm. Using a web program (sample size calculator: one sample mean) the minimum number of participants was determined to be 15.9
with the dominant and non-dominant hands,8 we should assign the participant’s hand, which will perform chest compression because only one hand is used in performing OHCC. The hands were assigned by a randomisation list arranged by random number sequences from web-based computer software using six permuted blocks (1. AABB, 2. ABAB, 3. ABBA, 4. BBAA, 5. BABA, 6. BAAB). The participants assigned to the letter of ‘A’ performed OHCC with the right hand and to the letter of ‘B’ performed OHCC with the left hand. The randomisation list was created before the experiment by the chief of the research. The researchers supervising data collection instructed participants which hand to perform OHCC. The participants were concealed about the allocation of hand and they used only the assigned hand during OHCC. Considering that the height of a hospital bed and the height of the participant’s knee might influence the compression depth, the manikin was placed in the supine position on a hard floor.10 To prevent participants from receiving feedback, the CPRmeter display was hidden. Audiovisual feedback to control the chest compression rate was not provided, because it could affect the chest compression depth.11
Study protocol
Outcome variables
The participants performed continuous OHCC for 2 min without ventilation using a simulated in-hospital paediatric arrest model, which included a Resusci Junior Basic and Skill Guide paediatric manikin (Laerdal Medical, Stavanger, Norway) and a CPRmeter (Laerdal Medical). Although it was reported that there was no significant difference in chest compression depth between OHCC
The mean compression depth (MCD) and the mean compression rate (MCR) collected by the CPRmeter were used as outcome variables. Data were calculated at 30 s intervals using the Q-CPR review program (ver. 3.1; Laerdal Medical).
Materials and methods The experiment consisted of single 2 min OHCC and performed at a university hospital. The present study was approved by the Institutional Review Board of our hospital (approval number C2014217(1414)).
Study population
Statistical analysis All statistical analyses were performed using the PASW statistics software (ver.
18.0; SPSS, Inc., Chicago, IL, USA). Data are presented as means ± SDs. The normality of the distribution of MCD and MCR data were analysed using a Shapiro–Wilk test. Normally distributed data were analysed using the two-sided paired t-test; otherwise, the Wilcoxon signed-rank test was used for statistical comparisons between the results of each 30 s interval. The Mann–Whitney U-test was used for statistical comparisons between the results of male and female and between the results of the right and left hand that performed OHCC. A P-value of < 0.05 was considered to indicate statistical significance.
Results Forty doctors (32 male, eight female), with a mean age of 26 ± 2.4 years, took part in the study. Twenty doctors performed OHCC with the right hand and twenty doctors with the left hand. The MCD values decreased significantly with time (Tables 2,3; Fig. 1). The MCR also tended to decrease with time, but the differences were statistically significant only between 30– 60 s and 60–90 s and between 30– 60 s and 90–120 s (Fig. 2). The MCD and MCR of the male participants were higher than the female participants, but the differences were statistically significant only in the MCR of the 30–60 s interval because the numbers of the female participants was small (Table 4). Comparisons of the MCD and MCR between the hands that performed OHCC were not different significantly (Table 5).
Discussion Previous studies have reported that long-term chest compression using adult manikins or adult patients might induce rescuer fatigue.2–5 However, previous simulation studies using child manikins have focused on chest compression technique rather than rescuer fatigue.12–14 Peska et al.13 documented that in 1 min paediatric CPR, the compression rate declined more rapidly with the OHCC technique than the THCC technique. Udassi et al. 14 demonstrated that compression depth, compression pressure and
© 2015 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine
110
JH OH ET AL.
TABLE 2.
The mean compression depths and mean compression rates during a 2 min period
MCD (mm) MCR (/min)
0–30 s
30–60 s
60–90 s
90–120 s
44.3 ± 4.1 119.3 ± 12.5
42.4 ± 4.9 119.0 ± 12.5
40.5 ± 5.8 117.9 ± 14.5
38.7 ± 5.7 117.8 ± 14.9
MCD, mean compression depth; MCR, mean compression rate.
TABLE 3.
The statistical comparisons between the results of each 30 s interval
Statistical comparisons MCD MCR
0–30 s versus 30–60 s
0–30 s versus 60–90 s
0–30 s versus 90–120 s
30–60 s versus 60–90 s
30–60 s versus 90–120 s
60–90 s versus 90–120 s
0.000 0.711
0.000 0.200
0.000 0.192
0.000 0.037
0.000 0.043
0.000 0.758
MCD, mean compression depth; MCR, mean compression rate. A P-value < 0.05 is presented in bold.
Figure 1.
Box plot of the mean compression depth during a 2 min period.
compression rate decreased over time in a 5 min paediatric CPR with both the OHCC and THCC techniques, but they did not report the time points that showed definite decreases. In 2013, Badaki-Makun et al.7 reported that experimental results obtained from longterm paediatric CPR were similar to those obtained from long-term adult CPR, but they did not describe the results of the OHCC technique. The OHCC technique is different from the THCC technique with several reasons. First, we can use only one hand when performing chest compres-
sions. In contrast, both hands with the fingers interlocked can be used when performing THCC. Second, the axis transmit power to the victim’s chest is not located in the centre of the rescuers. As a result the rescuer might not load their full weight onto their hand. Therefore more muscles might be used when performing OHCC. It might reasonably be expected that rescuer fatigue would be induced more rapidly by the OHCC technique than the THCC technique simply because the OHCC technique might need greater muscle effort.
In addition we note that chest compression quality was reduced abruptly after 1 min of CPR using adult manikins.2–4 Those studies compared percentages of correct chest compression, not MCD values. If there were any conditions that did not satisfy the manikin settings for ‘correct’ compression, the chest compression would be counted as a false compression even if sufficient depth was provided. Thus, they might have overestimated rescuer fatigue. In fact, Sugerman et al.5 indicated that in adult-patient CPR using a Q-CPR device, compression depth decreased more slowly after 90 s. We considered that if compression depth was measured using an accelerometer device, such as a CPRmeter, instead of the depth-measuring device of the manikin itself, compression depth could be determined more accurately. Thus, we measured compression data with a CPRmeter and calculated the MCD and MCR at 30 s intervals. The MCD values did decrease significantly after 30 s. The MCR values did not show a significant difference within 1 min, but decreased significantly thereafter. In contrast, Badaki-Makun et al.7 reported that MCR values increased over time. One reason for this difference might be that participants in our study performed chest compressions at a rate of ∼120 min−1 although the 2010 ERC guidelines recommend that the compression rate should be at least 100 min −1 but not greater than
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FATIGUE EFFECT ON ONE-HANDED CHEST COMPRESSION
Figure 2.
Box plot of the mean compression rates during a 2 min period.
TABLE 4.
Comparisons according to the sex of the participants Male (n = 32)
Time MCD (mm) MCR (/min) Time MCD (mm) MCR (/min) Time MCD (mm) MCR (/min) Time MCD (mm) MCR (/min)
44.8 ± 4.1 121.3 ± 11.8 42.9 ± 4.9 121.4 ± 12.6 41.1 ± 5.7 120.1 ± 14.0 39.5 ± 5.8 120.2 ± 14.2
Female (n = 8) 0–30 s 42.4 ± 3.7 111.1 ± 12.7 30–60 s 40.4 ± 4.9 109.5 ± 11.2 60–90 s 38.0 ± 5.7 108.9 ± 13.5 90–120 s 35.6 ± 4.5 108.1 ± 14.8
P-value 0.082 0.065 0.134 0.020 0.134 0.065 0.055 0.065
MCD, mean compression depth; MCR, mean compression rate. A P-value < 0.05 is presented in bold.
120 min−1. The MCR values in BadakiMakun et al.’s study increased from 106 min−1 to 117.5 min−1 slowly over 10 min. Another reason might be that participants in our study were aware of the test period (2 min) before the test. Thus, they might have performed chest compressions at their maximum speed. However, because OHCC was performed for only 2 min in our study, the effects of rescuer fatigue on the compression rate were difficult to determine. The decrease of the compression depth during 2 min in our study was
only 5.6 mm. The 5.6 mm is a small value but it exceeds 10% of the recommended compression depth of the paediatric CPR.6 The guideline emphasised on achieving an adequate depth of compression; at least 1/3 of the anterior–posterior chest diameter in all children (i.e. approximately 5 cm in children).6 The recent studies supported that increased compression depths were associated with better survival compared with shallower compression depths in both adults and paediatric populations.15,16 Therefore the maintenance of
chest compression depth is important even if it is a small value. Based on our results, strategies for effective OHCC require the following considerations to maintain constant chest compression quality. First, compression depth can be maintained by converting the OHCC technique into the THCC technique within 1 min. Second, because there is apparently no significant difference in the chest compression quality of OHCC using the dominant versus nondominant hand,8 chest compression quality can be maintained by using the other hand within 1 min. Third, to maintain chest compression quality, paediatric CPR using the OHCC technique can be performed by changing the rescuer within 1 min. Because these considerations were based on our experimental results, further simulation studies are needed to confirm them. Additionally, it is worth considering that frequent changes of the hand or the rescuer might prolong the interruption times in chest compression. The results of the present study are subject to several limitations. First, because this was a simulation study, the results might not be applicable to the clinical situation. Second, because we used a simulated in-hospital paediatric arrest model, continuous OHCC was performed without ventilation. Thus, different results may be obtained in an out-of-hospital setting or in conditions without application of advanced airway. We performed CPR on a manikin on the floor, not on a bed, to exclude the difference in position between the manikin and the rescuer, which is not the same as the real-life in-hospital arrest situation. Third, although compression depth decreased significantly after 30 s, it did not reach the 5 cm during all intervals that is recommended by current guidelines for paediatric CPR. This might have been because the participants in our study were relatively novice rescuers, although they were healthcare providers who took their medical doctor licensure within 1 year. Other reasons might include the high compression rate and the manikin’s characteristics. Another study using the same manikin also reported chest compression depths below 5 cm.7 Finally,
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JH OH ET AL.
TABLE 5. Comparisons according to the performing hand of the participants Right hand (n = 20) Time MCD (mm) MCR (/min) Time MCD (mm) MCR (/min) Time MCD (mm) MCR (/min) Time MCD (mm) MCR (/min)
44.4 ± 4.6 115.6 ± 11.2 42.0 ± 5.1 115.3 ± 11.3 39.8 ± 6.1 113.6 ± 12.5 38.0 ± 6.2 113.0 ± 13.3
Left hand (n = 20) 0–30 s 44.2 ± 3.6 123.3 ± 12.9 30–60 s 42.9 ± 4.8 123.1 ± 14.1 60–90 s 41.3 ± 5.4 122.6 ± 15.3 90–120 s 39.5 ± 5.2 123.1 ± 15.1
P-value
7.
0.789 0.078 8. 0.668 0.130 0.611 0.093 0.630 0.061
9.
MCD, mean compression depth; MCR, mean compression rate.
10.
because CPR was performed for 2 min, the effects of rescuer fatigue on MCR might not have been determined fully. Further studies on this issue are warranted.
Conclusions Compression depth decreased significantly after 30 s during continuous OHCC using a simulated paediatric arrest model. The results of the present study suggest that future strategies for child victims should be established to prevent a decrease in compression depth within 1 min during performance of the OHCC technique.
Acknowledgement We thank all participants for their contribution in the present study.
Author contributions JHO was responsible for the conception and design of the study. CWK, SEK and DHL were responsible for the acquisition of data. JHO was responsible for analysis and interpretation of data. JHO, CWK and SEK were responsible for drafting the article or revising it critically for important intellectual content. SEK was responsible for the final approval of the version to be submitted.
Competing interests None declared. 11.
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© 2015 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine
