Excessive chest compression rate is associated with insufficient compression depth in prehospital cardiac arrest

Background and goal of study

The relationship between chest compression rate and compression depth is unknown. In order to characterise this relationship, we performed an observational study in prehospital cardiac arrest patients. We hypothesised that faster compressions are associated with decreased depth.

Materials and methods

In patients undergoing prehospital cardiopulmonary resuscitation by health care professionals, chest compression rate and depth were recorded using an accelerometer (E-series monitor-defibrillator, Zoll, USA). Compression depth was compared for rates <80/min, 80–120/min and >120/min. A difference in compression depth ≥0.5 cm was considered clinically significant. Mixed models with repeated measurements of chest compression depth and rate (level 1) nested within patients (level 2) were used with compression rate as a continuous and as a categorical predictor of depth. Results are reported as means and standard error (SE).

Results and discussion

One hundred and thirty-three consecutive patients were analysed (213,409 compressions). Of all compressions 2% were <80/min, 62% between 80 and 120/min and 36% >120/min, 36% were <4 cm deep, 45% between 4 and 5 cm, 19% >5 cm. In 77 out of 133 (58%) patients a statistically significant lower depth was observed for rates >120/min compared to rates 80–120/min, in 40 out of 133 (30%) this difference was also clinically significant. The mixed models predicted that the deepest compression (4.5 cm) occurred at a rate of 86/min, with progressively lower compression depths at higher rates. Rates >145/min would result in a depth <4 cm. Predicted compression depth for rates 80–120/min was on average 4.5 cm (SE 0.06) compared to 4.1 cm (SE 0.06) for compressions >120/min (mean difference 0.4 cm, P < 0.001). Age and sex of the patient had no additional effect on depth.

Conclusions

This study showed an association between higher compression rates and lower compression depths. Avoiding excessive compression rates may lead to more compressions of sufficient depth.     

An audiovisual feedback device for compression depth, rate and complete chest recoil can improve the CPR performance of lay persons during self-training on a manikin

This study aims to contribute to the scarce data available about the abilities of untrained lay persons to perform hands-only cardio-pulmonary resuscitation (CPR) on a manikin and the improvement of their skills during training with an autonomous CPR feedback device. The study focuses on the following questions: (i) Is there a need for such a CPR training device? (ii) How adequate are the embedded visual feedback and audio guidance for training of lay persons who learn and correct themselves in real time without instructor guidance? (iii) What is the achieved effect of only 3 min of training? This is a prospective study in which 63 lay persons (volunteers) received a debriefing to basic life support and then performed two consecutive 3 min trials of hands-only CPR on a manikin. The pre-training skills of the lay persons were tested in trial 1. The training process with audio guidance and visual feedback from a cardio compression control device (CC-Device) was recorded in trial 2. After initial debriefing for correct chest compressions (CC) with rate 85-115 min(-1), depth 3.8-5.4 cm and complete recoil, in trial 1 the lay persons were able to perform CC without feedback at mean rate 95.9 ± 18.9 min(-1), mean depth 4.13 ± 1.5 cm, with low proportions of 'correct depth', 'correct rate' and 'correct recoil' at 33%, 43%, 87%, resulting in the scarce proportion of 14% for compressions, which simultaneously fulfill the three quality criteria ('correct all'). In trial 2, the training process by the CC-Device was established by the significant improvement of the CC skills until the 60th second of training, when 'correct depth', 'correct rate' and 'correct recoil' attained the plateau of the highest quality at 82%, 90%, 96%, respectively, resulting in 73% 'correct all' compressions within 3 min of training. The training was associated with reduced variance of the mean rate 102.4 ± 4.7 min(-1) and mean depth 4.3 ± 0.4 cm, indicating a steady CC performance achieved among all trained participants. Multivariable linear regression showed that the compression depth, rate and complete chest recoil did not strongly depend on lay person age, gender, height, weight in pre-training and training stage (correlation coefficient below 0.54). The study confirmed the need for developing CPR abilities in untrained lay persons via training by real-time feedback from the instructor or CC-Device. The CC-Device embedded feedback was shown to be comprehensible and easy to be followed and interpreted. The high quality of the CC-Device-assisted training process of lay persons was confirmed. Thus learning or refresher courses in basic life support could be organized for more people trained at the same time with fewer instructors needed only for the initial debriefing and presentation of the CC-Device.     

Pulse rate as an alternative,real-time feedback indicator for chest compression rate: a porcine model of cardiac arrest

Journal of Clinical Monitoring and Computing - Feedback indicators can improve chest compression quality during cardiopulmonary resuscitation (CPR). However, the application of feedback indicators...     

Accurate feedback of chest compression depth on a manikin on a soft surface with correction for total body displacement

Objective

TrueCPR is a new real-time compression depth feedback device that measures changes in magnetic field strength between a back pad and a chest pad. We determined its accuracy with a manikin on a test bench and on various surfaces.

Methods

First, calibration and accuracy of the manikin and TrueCPR was verified on a drill press. Then, manual chest compressions were given, on a firm surface and on a foam or air mattress, with feedback of the TrueCPR or Q-CPR accelerometer, to achieve a depth of 50 mm. Compression depth measurements by the devices and the manikin were compared.

Results

On a hard surface TrueCPR showed a systematic underestimation of 2–3 mm in the drill press. Manual tests on a hard surface showed a slightly larger underestimation of 4.5 mm. When guided by TrueCPR on a foam or air mattress, the TrueCPR measured a mean(±SD) chest compression depth of 52.0(±1.9) mm and 49.4(±2.6) mm respectively, while the manikin measured 54.4(±1.8) mm and 52.1(±1.4) mm, respectively (p < 0.001). When guided by the Q-CPR accelerometer on a foam or air mattress, the accelerometer measured depth of 54.3(±3.6) mm and 56.0(±3.8) mm respectively, compared to the manikin 42.4(±2.3) mm and 34.9(±3.6) mm, respectively (p < 0.001).

Conclusion

TrueCPR measures depth precisely, independent of the stiffness of the surface upon which the CPR is being performed with a constant inaccuracy of <4.5 mm. A sternum-only accelerometer substantially overestimates depth when performing CPR on a soft surface. Correction for body displacement on a soft surface is essential for accurate delivery of chest compressions within the recommended depth range.     

Chest compression rate feedback based on transthoracic impedance

BackgroundQuality of cardiopulmonary resuscitation (CPR) is an important determinant of survival from cardiac arrest. The use of feedback devices is encouraged by current resuscitation guidelines as it helps rescuers to improve quality of CPR performance.AimTo determine the feasibility of a generic algorithm for feedback related to chest compression (CC) rate using the transthoracic impedance (TTI) signal recorded through the defibrillation pads.MethodsWe analysed 180 episodes collected equally from three different emergency services, each one using a unique defibrillator model. The new algorithm computed the CC-rate every 2 s by analysing the TTI signal in the frequency domain. The obtained CC-rate values were compared with the gold standard, computed using the compression force or the ECG and TTI signals when the force was not recorded. The accuracy of the CC-rate, the proportion of alarms of inadequate CC-rate, chest compression fraction (CCF) and the mean CC-rate per episode were calculated.ResultsIntervals with CCs were detected with a mean sensitivity and a mean positive predictive value per episode of 96.3% and 97.0%, respectively. Estimated CC-rate had an error below 10% in 95.8% of the time. Mean percentage of accurate alarms per episode was 98.2%. No statistical differences were found between the gold standard and the estimated values for any of the computed metrics.ConclusionWe developed an accurate algorithm to calculate and provide feedback on CC-rate using the TTI signal. This could be integrated into automated external defibrillators and help improve the quality of CPR in basic-life-support settings.     

Effect of mattress and bed frame deflection on real chest compression depth measured with two CPR sensors

Aim

Implementation of chest compression (CC) feedback devices with a single force and deflection sensor (FDS) may improve the quality of CPR. However, CC depth may be overestimated if the patient is on a compliant surface. We have measured the true CC depth during in-hospital CPR using two FDSs on different bed and mattress types.

Methods

This prospective observational study was conducted at Tampere University Hospital between August 2011 and September 2012. During in-hospital CPR one FDS was placed between the rescuer's hand and the patient's chest, with the second attached to the backboard between the patient's back and the mattress. The real CC depth was calculated as the difference between the total depth from upper FDS to lower FDS.

Results

Ten cardiac arrests on three different bed and mattress types yielded 10,868 CCs for data analyses. The mean (SD) mattress/bed frame effect was 12.8 (4) mm on a standard hospital bed with a gel mattress, 12.4 (4) mm on an emergency room stretcher with a thin gel mattress and 14.1 (3) mm on an ICU bed with an emptied air mattress. The proportion of CCs with an adequate depth (≥50 mm) decreased on all mattress types after compensating for the mattress/bed frame effect from 94 to 64%, 98 to 76% and 91 to 17%, in standard hospital bed, emergency room stretcher and ICU bed, respectively (p < 0.001).

Conclusion

The use of FDS without real-time correction for deflection may result in CC depth not reaching the recommended depth of 50 mm.     

The relationship between rate of chest compression and compression:relaxation ratio

One of the arguments put forward in support of a relatively fast rate of chest compression during CPR, is that it facilitates the achievement of a high compression:relaxation ratio. This has been shown to increase blood flow. In this study a group of volunteers carried out chest compression at the rate that each felt was correct and comfortable. There was no significant relationship between compression rate and compression:relaxation ratio. In a second study volunteers carried out chest compression on a manikin at rates of 40/min; 60/min; 80/min and 100/min. There was no significant rate related difference in the compression:relaxation ratios recorded. The ability to achieve a high compression duration is not related to compression rate, and should not be a consideration when guidelines on CPR are revised.     

Factors influencing quality of chest compression depth in nursing students

The purpose of the study was to identify factors influencing quality of chest compression depth in nursing students. A convenience sample of 102 female nursing students enrolled in a cardiopulmonary resuscitation skills training session. Each student performed 3 min of chest compression skills on a Resusci Anne SkillReporter manikin for measurements of both depth and rate. Nursing students with correct compression depth (50–60 mm) had higher body weight (t = ?2.02, P = 0.046) and body mass index (t = ?2.19, P = 0.031) compared with students in the incorrect depth group. Mean chest compression depth was shallower in underweight nursing students compared with normal weight or overweight students (F = 8.89, P < 0.001). Body weight was a significant factor influencing quality of chest compression depth (F = 4.25, P = 0.003). Educational intervention targeting underweight nursing students might need to enhance the quality of chest compression skills.     

Effect of season, age, and gender on renal colic incidence

Our objective was to examine the effect of ambient temperature, age, and gender on the incidence of emergency department (ED) renal colic visits. We retrospectively analyzed a database of 15 New Jersey EDs from January 1, 1996 to December 31, 2002. We analyzed the number of renal colic visits as a fraction of total visits in monthly intervals. We used the Chi-squared test and Pearson's correlation coefficient, with P<.05 taken as statistically significant. Of the 3.5 million patient visits in the database, 30,358 (0.9%) had renal colic. Renal colic visits were 16% more likely in warmer than colder months (P<.001) and this effect was greatest in older patients and males. We conclude that higher ambient temperature, older age and male gender are associated with increased incidence of ED renal colic visits. Advice to patients, especially older males, to avoid dehydration particularly during hot weather may help prevent bouts of renal colic.     

The use of dual accelerometers improves measurement of chest compression depth

Background

Chest compression (CC) feedback devices are used to perform CC measurements effectively and accurately on patients in hospital beds. However, these devices do not take account of the compression of the mattress, which results in overestimation of CC depth. In this study, we propose a new method using two accelerometers to overcome this limitation and thus measure compression depth more accurately when performing cardiopulmonary resuscitation (CPR) on patients.

Method

One accelerometer was placed on the manikin's sternum (a1), and the other between the manikin's back and the mattress (a2). The compression depth was calculated by integrating the acceleration twice using a digital signal processing technique. We compared CC depth from dual accelerometers and single accelerometer (a1) on the foam and inflated air mattress with eight CPR providers.

Result

When CC was done on a manikin lying on the floor, there was no significant difference between measurement techniques (p > 0.05). When CC was done on a manikin lying on the foam and inflated air mattress supporting system, our method significantly improved the estimation of CC depth, irrespective of the presence or absence of a backboard (p < 0.001).

Conclusion

Measuring CC depth using two accelerometers is more effective than using one in increasing the accuracy of CC depth estimation when CPR is performed on the foam and inflated air mattress, regardless of the presence or absence of a backboard.     

Force and depth of mechanical chest compressions and their relation to chest height and gender in an out-of-hospital setting

IntroductionThe LUCAS 2 device stores technical data that documents the chest compression process. We analyzed chest wall dimensions and mechanics stored during chest compressions on humans using data gathered with the LUCAS 2 device.MethodsData from LUCAS 2 devices used in out-of-hospital cardiac arrest were downloaded with dedicated proprietary software and matched to the corresponding patient data. Cases were included only if the suction cup was placed correctly, if it was not realigned during the first 5 min of chest compressions, and if no other anomaly in device use was noted. Trauma cases were excluded.ResultsNinety-five patients were included. All patients received manual cardiopulmonary resuscitation prior to the application of the device. The mean (SD) chest height was 232 (25) mm for males and 209 (26) mm for females (P < 0.001). The mean (min–max) compression depth in patients with chest height >185 mm was 53 (50–55) mm, corresponding with 19–28% of the chest diameter. The mean force required to achieve the compression depth of 53 mm ranged between 219 and 568 N. No correlation was found between chest height and force to reach 53 mm depth (females: R² = 0.001, males: R² = 0.007).ConclusionThere was a large variation of the required force to achieve a compression depth of 53 mm. No correlation was seen between chest height and maximum force required to compress the chest 53 mm.     

Effect of gender, age, and anthropometry on axial and appendicular muscle strength

OBJECTIVE: To assess age and gender differences in muscle strength. DESIGN: The strength of back extensors, upper limbs (grip), and lower limbs (knee extensors) was measured. Anthropometric measurements and body mass index also were assessed. RESULTS: Group comparisons were made for each decade. Back extensor strength (BES) in subjects aged 20 to 89 yr ranged from 93 to 832 N in men and from 71 to 440 N in women. BES peaked in the fourth decade for men and in the fifth decade for women. When the two genders were compared, muscle strength in women was less than that in men at all ages. At different decades, women's BES ranged from 54% to 76% compared with that of men's BES. There was a 64% loss of BES in men from the peak in their fourth decade (556 N) to the lowest level in their ninth decade (201 N). Women experienced a 50.4% loss from the peak in their fifth decade (306 N) to the lowest level in their ninth decade (152 N). CONCLUSIONS: Men had a greater loss of BES than women with increasing age. In both genders, there was more loss of BES than appendicular muscle strength. Reduction in BES in women coincided with increased body mass index in older age. In women, there was a negative correlation between body weight and level of physical activity, whereas this finding was not evident in men. Background factors related to a higher incidence of back pain, falls, and fractures, especially in women, may be a reduction in muscle strength, along with increasing age and body mass index. This cross-sectional study showed that physiologic reduction of muscle strength, which began early in life, later stopped and that muscle strength even improved, despite the aging process. Therefore, initiating strengthening exercises at any age is encouraged to prevent the impact of several age-related musculoskeletal challenges.     

Development of a real-time feedback algorithm for chest compression during CPR without assuming full chest decompression

Objectives

To evaluate the performance of a real-time feedback algorithm for chest compression (CC) during cardiopulmonary resuscitation (CPR), which provides accurate estimation of the CC depth based on dual accelerometer signal processing, without assuming full CDC. Also, to explore the influence of incomplete chest decompression (CDC) on the CC depth estimation performance.

Methods

The performance of a real-time feedback algorithm for CC during CPR was evaluated by comparison with an offline algorithm using adult CPR manikin CC data obtained under various conditions.

Results

The real-time algorithm, using non-causal baselining, delivered comparable CC depth estimation accuracy to the offline algorithm on both soft and hard back support surfaces. In addition, for both algorithms incomplete CDC led to underestimation of the CC depth.

Conclusions

CPR feedback systems which utilize an assumption of full CDC may be unreliable especially in long duration CPR events where rescuer fatigue can strongly influence CC quality. In addition, these systems may increase the risk of thoracic and abdominal injury during CPR since rescuers may apply excessive compression forces due to underestimation of the CC depth when incomplete CDC occurs. Hence, there is a strong need for CPR feedback systems to accurately measure CDC in order to improve their clinical effectiveness.     

Family caregiver issues: gender, privacy, and public policy perspectives

Due to the phenomenon of Taiwan'saging population has made, long-term care has become an issue of increasingly emphasized importance. According to the statistics, the family takes responsibility for most long-term care duties and more than 70% of primary family caregivers are female. In the past, because of gender-based divisions of labor and gender role expectations made, it was taken for granted that females would be the socially preferred family caregivers. Those men who devoting in themselves to such work were regarded as a rare precious. As such, family care signified entailed different life experiences for males and females. Over the years, amendments to the civil code have recognized family care contributions, and the allowance for caregivers underlines that care responsibilities have shifted away from the family to society. Traditional gender divisions of labor today are significantly more blurred; family structures have become smaller in size; female labor in the workplace has increased; and ten-year long-term care plans and long-term care insurance have been successively implemented. These transformations will make labor outsourcing more and more popular and transform family care from a private problem to a pubic policy issue. In the future, family caregivers require consideration and support on a sustained basis. It is also important to improve and monitor the quality of care services. Nurses, the major professional members of long-term care teams, should be concerned over the issue of family care while providing nursing care. They should include family caregivers in the care plan so that they can make sure that patients receive comprehensive and constant care in order to enhance the overall quality of nursing care.     

Influence of chest compression rate guidance on the quality of cardiopulmonary resuscitation performed on manikins

AimsThe adequate chest compression rate during CPR is associated with improved haemodynamics and primary survival. To explore whether the use of a metronome would affect also chest compression depth beside the rate, we evaluated CPR quality using a metronome in a simulated CPR scenario.MethodsForty-four experienced intensive care unit nurses participated in two-rescuer basic life support given to manikins in 10 min scenarios. The target chest compression to ventilation ratio was 30:2 performed with bag and mask ventilation. The rescuer performing the compressions was changed every 2 min. CPR was performed first without and then with a metronome that beeped 100 times per minute. The quality of CPR was analysed with manikin software. The effect of rescuer fatigue on CPR quality was analysed separately.ResultsThe mean compression rate between ventilation pauses was 137 ± 18 compressions per minute (cpm) without and 98 ± 2 cpm with metronome guidance (p < 0.001). The mean number of chest compressions actually performed was 104 ± 12 cpm without and 79 ± 3 cpm with the metronome (p < 0.001). The mean compression depth during the scenario was 46.9 ± 7.7 mm without and 43.2 ± 6.3 mm with metronome guidance (p = 0.09). The total number of chest compressions performed was 1022 without metronome guidance, 42% at the correct depth; and 780 with metronome guidance, 61% at the correct depth (p = 0.09 for difference for percentage of compression with correct depth).ConclusionsMetronome guidance corrected chest compression rates for each compression cycle to within guideline recommendations, but did not affect chest compression quality or rescuer fatigue.