Comparison of chest compression quality between 2-minute switch and rescuer fatigue switch: A randomized controlled trial.

Background: Rescuers performing chest compressions (CCs) should be rotated every 2 min or sooner if rescuers become fatigued. Is it preferable to switch rescuers when they become fatigued in such cases? This study was performed to compare the quality of CCs between two scenarios in hospitalized patients with cardiac arrest: 2-minute rescuer switch and rescuer fatigue switch.
Methods: This randomized controlled trial involved 144 health-care providers, randomized to switch CC on the manikin model with 2-minute or rescuer fatigue. We recorded the CC quality for 20 min.
Results: There were no significant differences in the percentage of target compressions, mean depth of compressions, or mean compression rate between the two groups. However, the rescuer fatigue switch group showed a significantly lower frequency of interruptions (4 vs. 9 times, P < 0.001) and a longer duration of each compression cycle (237 vs. 117 sec, P < 0.001). The change in the respiratory rate from before to after performing compressions was significantly greater in the 2-minute switch group (12 vs. 8 bpm, P = 0.036).
Conclusion: The use of a rescuer fatigue switch CC approach resulted in no decrease in the quality of CC, suggesting that it may be used as an alternate strategy for managing in-hospital cardiac arrest. Copyright:

INTRODUCTION

In-hospital cardiac arrest (IHCA) is a common problem in the emergency department. International reports of survival after IHCA range from 20% to 73%.[1] In Thailand, a previous study reported that the survival after IHCA was 29%.[2] One of the five most essential steps in the chain of survival is immediate high-quality chest compression (CC). The important concept of effective CC is the performance of continuous CC at a rate of 100−120 breaths/min at a depth of at least 2 in (5 cm) but no more than 2.4 in (6 cm). The chest should be allowed to fully recoil after each compression. To enhance the quality of cardiopulmonary resuscitation (CPR), the guidelines recommend minimal interruptions of CC and changing the rescuer performing the CC every 2 min or promptly when tiredness begins.[3]

Ochoa et al.[4] and Hightower et al.[5] observed that the quality of CC worsened after 1 min, with rescuers usually unaware of this worsening. In another study, Sugerman et al.[6] reported that the compression depth was reduced but that the compression rate remained constant at 90 s. Ashton et al.[7] and Huseyin et al.[8] reported that when performance deteriorated, CC should be renewed every 1 min. Furthermore, McDonald et al.[9] recommend changing CC every 2 min; this is consistent with the findings of Manders et al.,[10] who found no difference between altering the CC every 1 and 2 min. However, recent research has shown the benefits of alternating CC based on the fatigue of the rescuers. If fatigue sets in, changing the rescuer who performs the CC before 2 min has elapsed is more efficient than changing the rescuer every 2 min.[11]

However, the time to onset and impact of rescuer fatigue varies between individuals. Thus, it is important to determine if compression quality is compromised by switching rescuers according to their fatigue level at time points other than the 2-min mark to best utilize each rescuer optimally according to their abilities. This study aims to determine if switching rescuers in a simulated resuscitation environment according to rescuer fatigue level rather than predetermined 2-min time intervals will result in a significant decline in the quality of CC delivered to the simulated patient.

METHODS

Study design

This experimental study (randomized controlled trial) was performed at a single center with a 1:1 allocation ratio to compare the 2-minute switch method with the rescuer fatigue switch method. The study involved medical professionals and was conducted from October 31, to November 30, 2016. Using sequentially numbered, opaque sealed envelopes, the participants were separated into pairs. The four-randomization block had previously been statistically split into pairs A and B. Randomization was accomplished using Research Randomizer© (Urbaniak GC and Plous S, 2013) a computer software available from https://www.randomizer.org. Participants were separated into two groups: the 2-minute switch method group and the rescuer fatigue switch method group [Figure 1].

Figure 1

Study flow

Experimental procedures

The experimental setup was explained to all participants by verbal and participant information sheets. It took no more than 10 min to fill out participant's information record sheet and informed consent form. Before the experiment, each participant's pulse rate and respiration rate were measured. Each participant was given a pair of adult CCs on the CPR Dashboard of the ZOLL® X Series® monitor/defibrillator (ZOLL Medical, Chelmsford, MA, USA), which were then appropriately positioned for CC on a BRAYDEN CPR Training Manikin (Aero Healthcare, Valley Cottage, NY, USA). The manikin was placed on a hard surface table at the height of 75 cm, equal to the height of a standard patient stretcher at our institution. A 2-steps stool (height 30 cm) was placed beside for voluntary participant use. The quality of compressions was instantly visible on the screen of the ZOLL® X Series® monitor/defibrillator.

In the 2-minute switch method group, CC was performed continuously for 2 min, and the participants alternated when an alarm sounded. This was repeated for 10 cycles (5 cycles for each participant) for a total of 20 min. The participants were not allowed to stop compression early if they fatigue. During the rest period of the switching process, the participants were placed in a position above the manikin until they were weary or ready to resume CCs. The research supervisor was notified of the recuperation time, which was then recorded. The rescuer fatigue switch method group followed the same procedure as the 2-minute switch method group except that they continued CCs and then spoke for 20 min when tired [Figure 2]. While performing the CC, a cardiac monitor was used to provide an audio assessment of the quality of CC, but participants were not allowed to view the monitor's screen which displayed the rate and depth of CC and rate of fully chest recoil. We collect the results unique to each compressor. During the last set of CC at the end of the study, the pulse rate and respiratory rate were measured again. We use the ZOLL® X Series® monitor/defibrillator to measure the chest compressor's pulse and respiratory rates before and after CC. The data were collected by persons who had no conflict of interest in the study.

Figure 2

Experimental procedures

Participants

All study participants were physicians, resident physicians, nurses, emergency medical technicians (EMTs), nursing students, paramedic students, and other health-care providers who provided informed consent to participate in the study. Those who had performed CC within 24 h before participating in the study were excluded.

Sample size calculation

Based on a previous report,[11] this study required 72 trials (pairs) divided into 36 experiments (pairs) for the 2-minute switch method and 36 experiments (pairs) for the rescuer fatigue switch method. The calculations were based on an alpha error of 0.05 and power of 80%. Comparison of two independent means was used to calculate the sample size.

Statistical analyses

Clinical data were calculated using descriptive statistics and presented as mean and standard deviation for continuous data or number and percentage for categorical data. Data and results were compared among the independent groups. The Mann−Whitney U-test or Student's t-test was used to compare continuous data and the Chi-square test or Fisher's exact test was used to compare categorical data between the two groups, as appropriate. A P < 0.05 was considered statistically significant.

Because this study included several iterative results, the intraclass correlation and interclass correlation had to be considered. A multilevel technique was employed in an independent-group comparison for repeated-measured variables, which included taking into consideration the harmony of the performance of CC within the same pair and between pairs. For categorical data, the study results were compared using a mixed-effects logistic regression analysis using the “xtmelogit” command and presented as the odds ratio (95% confidence interval), while continuous data were compared using a mixed-effects linear regression analysis using the “xtreg” command and displayed with a coefficient (95% confidence interval). All statistical analyses were performed using STATA software, version 14 (StataCorp, College Station, TX, USA).

RESULTS

This study involved 144 participants and all of them completely participated throughout the experiment. The participants comprised 93 (64.6%) health-care students, 43 (29.8%) physicians, and 8 (5.6%) nurses and EMTs with a mean age of 24.9 ± 3.8 years. Sixty-two (43.1%) participants were male. The mean weight was 63 ± 14 kg and the mean height was 165 ± 8 cm. There were no statistically significant differences in these baseline characteristics between the two groups [Table 1].

Table 1

Baseline characteristics

	2 min switch (36 pairs)	Rescuer fatigue switch (36 pairs)	P
Age (years)	24.94±3.76	24.90±3.91	0.948
Sex
Same sex	13 (36.11)	15 (41.67)	0.629
Different sex	23 (63.89)	21 (58.33)
Weight (kg)	63.07±16.38	63.26±12.48	0.936
Height (cm)	165±8.50	166±7.30	0.278
BMI (kg/m2)	23.07±5.00	22.83±4.10	0.758
Occupation
Health-care students	44 (61.11)	49 (68.06)	0.125
Physicians	26 (36.11)	17 (23.61)
Nurses and EMTs	2 (2.78)	6 (8.33)
BLS 2010/2015 certification	69 (95.83)	69 (95.83	1.000
Experience performing CPR
None	17 (23.61)	12 (16.67)	0.114
<1 year	20 (27.78)	34 (47.22)
1-3 years	8 (11.11)	7 (9.72)
>3 years	27 (37.50)	19 (26.39)
Exercises per week
0	34 (47.22)	29 (40.28)	0.339
1-2	27 (37.50)	25 (34.72)
≥3	11 (15.28)	18 (25.00)

Data are presented as n (%) and mean±SD. BMI: Body mass index, BLS: Basic life support, CPR: Cardiopulmonary resuscitation, SD: Standard deviation

As shown in Table 2, comparison of the quality of CC between the rescuer fatigue switch method group and the 2-minute switch method group revealed a significant difference in the number of CC interruptions (4 vs. 9 times, respectively; P < 0.001), total duration of interruptions (19 vs. 36 sec, respectively; P < 0.001), and duration of CC cycles (237 vs. 117 sec, respectively; P < 0.001). However, there was no significant difference in the mean interruption time (3.76 vs. 3.97 sec, respectively; P = 0.808). The data also showed that the rescuer fatigue switch method group outperformed the 2-minute switch method group in terms of the compression rate, compression depth, and proportion of standard CC. The proportion of standard CC in the 2-minute switch method group was 16.67, while that in the rescuer fatigue switch method group was 21.88.

Table 2

Quality of chest compressions

	2 min switch (36 pairs)	Rescuer fatigue switch (36 pairs)	P
Chest compression interruption	9	4 (0-10)	<0.001
Duration of interruption at each time (s)	3.97±1.00	3.76±2.10	0.808
Total duration of interruption (s)	36±9.00	19±16.00	<0.001
Duration of each cycle of chest compression (s)a	117 (114-118)	237 (101-1200)	<0.001
Compression rate (bpm)	119±9.60	116±10.40	0.166
Compression depth (cm)	4.86±0.54	4.84±0.52	0.876
Percentage of compression with sufficient ratea	40.23 (9.22-91.35)	50.76 (0.00-96.29)	0.478
Percentage of compression with sufficient deptha	38.44 (0.75-83.97)	40.35 (1.26-89.39)	0.652
Percentage of high-performance compressiona	16.67 (0.12-76.22)	21.88 (0.07-85.68)	0.423
Recuperation time (s)a	71 (0-119)	66 (0-127)	0.987
Difference in pulse rate (bpm)	24.0±0.70	23.5±0.64	0.507
Difference in respiratory rate (bpm)	12±0.26	8±0.24	0.036

a Data are presented as n (minimum–maximum): Sufficient rate=Perform chest compressions 100-120 times/min, Sufficient depth=Perform chest compressions 5 cm-6 cm depth, High-performance compression=Perform chest compressions 100-120 times/min and 5 cm-6 cm depth, Recuperation time=The rest period that chest compressor can continue the subsequent chest compressions. Data are presented as n (%) and mean±SD. SD: Standard deviation

The difference in the pulse and respiratory rates between before and after performing CC reflects the tiredness of the participants. The difference in the respiratory rate after performing CC was significantly greater in the 2-minute switch method group than in the rescuer fatigue switch method group (12 vs. 8 bpm; P = 0.036).

No significant differences were found between the two study groups when the proportion of standard CC was analyzed in subgroups separated by the compression rate and compression depth from minutes 1−20 [Figures 3-5].

Figure 3

Percentage of compression with sufficient rate for 20 min duration

Figure 5

Percentage of high-performance compression for 20 min duration

Percentage of compression with sufficient depth for 20 min duration

DISCUSSION

In the present manikin study that simulated IHCA, the use of rescuer fatigue switch method dramatically minimized the number of changes in rescuers performing CC and the total length of interruptions. This occurred because the rescuers in this group were able to perform CC for a longer period of time in each cycle than the rescuers in the 2-minute switch method group. In addition, the quality of CC did not substantially differ between the two groups. In comparison of the compression rate, compression depth, and proportion of standard CC, we found that the mean CC depth in both groups was less than the norm. As a result, the proportion of standard CC duty presses was also low. This might have occurred because of constraints in the manikin and the CPR Dashboard, which are both stiffer than an actual patient. This experimental study also employed a realistic total time of CC. As a result, when CC is necessary for extended periods of time in real practice, this may imply lower-than-standard CC quality.

The guidelines recommend minimal interruptions of CC and changing the rescuer performing the CC every 2-minutes or promptly when tiredness begins.[3] For a considerable reduction in compressions switched in the rescuer fatigue switch method group while maintaining compression quality. In a study by Pechaksorn et al.,[12] there were a significantly higher compression depth and lower rescuer fatigue in the 1-min CC group compared with the 2-min group. In a study by Huseyin et al.,[8] which examined the quality of CC with replacement every 1, 2, or 3 min between two-and three-person compression teams for 18 min, the change in CC every 1 min was significantly more effective than the other scenarios. In addition, the efficacy of CC was highest in the three-person team. Manders et al.[10] found that changing compressions at 1-and 2-min had no effect on CC quality. Notably, all of these studies provided data suggesting the optimal time to execute various CC. This demands the performance of more experimental studies involving animal models. After evaluating additional outcomes such as cerebral perfusion pressure and coronary perfusion pressure, it is possible to provide unequivocal recommendations for changing the course of CPR.

The median duration of CC in each cycle in the rescuer fatigue switch method group was 237 s, which differs from that in a previous study[11] showing that the average duration of compressions in the rescuer fatigue switch method group was 95 s. That result was derived using a research methodology that required the shift to occur immediately before or after 2 min, and most of the participants were female. In the present study, however, the participants’ mean age was quite young at 24.9 years, and the sex ratio in each pair was not different between the two study groups. As a result, the participants could push themselves for a longer period without tiring. The difference in the duration might also have been related to concern regarding each participant's research partner, causing the participants to attempt to keep the CC going for a longer period. A main drawback of this study is that it could not demonstrate real-time tiredness but instead utilized judgments made by individuals who may or may not be aware.

The duration of interruptions when switching CC was shorter in the rescuer fatigue switch method group than in the 2-minute switch method group, which was explained by more active communication between partners. Since it is personalized in the present study; however, the average time it took to alternate CC was not different between the two groups, probably because most of the participants had previously worked together. In addition, the operator suggested the use of an alternating CC drill in the first place. This allowed the alternating process to be well-co-ordinated.[10]

The change in the respiratory rate was higher in the 2-minute switch method group than in the rescuer fatigue switch method group. Fatigue increases by switching every 2 min. However, this has no effect on the quality of CC. It has no bearing on the termination of CC before the due date. As a result, it has no practical use in real-life settings.

Further research should be performed utilizing real-time audiovisual feedback devices to improve the effectiveness of CC, real-time feedback on performance and tiredness, and measurement of other variables to compare fatigue, such as the blood concentration of lactic acid.

Limitations

This study has several limitations. First, this research was conducted using manikins and simulated events. As a result, it is not representative of real-life situations. Second, because the data were obtained in a single center, the sample characteristics were not heterogeneous. Third, the experiment supervisor and data analyst were part of the same research team; as a result, the data could not be concealed. Finally, there was no use of real-time input on performance and weariness. Consequently, the evaluation was solely dependent on the participants’ opinions.

CONCLUSION

Alternation of CC based on fatigue limitations has no effect on the effectiveness of CC. This may be a better technique than alternating CC every 2 min for patients with IHCA.

Research quality and ethics statement

This study was approved by the Committee on Human Rights Related to Research Involving Human Subjects at Faculty of Medicine Ramathibodi Hospital, Mahidol University (Approval No. MURA2016/571; Approval date October 22, 2016). The authors followed the applicable EQUATOR Network guidelines, specifically the Strengthening the Reporting of Empirical Simulation Studies Guidelines, during the conduct of this research project.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.