The impact of backboard size and orientation on sternum-to-spine compression depth and compression stiffness in a manikin study of CPR using two mattress types

Finite Element Analysis of a Rib Cage Model: Influence of Four Variables on Fatigue Life during Simulated Manual CPR

Cardiopulmonary resuscitation (CPR) is a life-saving technique used in emergencies when the heart stops beating, typically involving chest compressions and ventilation. Current adult CPR guidelines do not differentiate based on age beyond infancy and childhood. This oversight increases the risk of fatigue fractures in the elderly due to decreased bone density and changes in thoracic structure. Therefore, this study aimed to investigate the correlation and impact of factors influencing rib fatigue fractures for safer out-of-hospital manual cardiopulmonary resuscitation (OHMCPR) application. Using the finite element analysis (FEA) method, we performed fatigue analysis on rib cage models incorporating chest compression conditions and age-specific trabecular bone properties. Fatigue life analyses were conducted on three age-specific rib cage models, each differentiated by trabecular bone properties, to determine the influence of four explanatory variables (the properties of the trabecular bone (a surrogate for the age of the subject), the site of application of the compression force on the breastbone, the magnitude of applied compression force, and the rate of application of the compression force) on the fatigue life of the model. Additionally, considering the complex interaction of chest compression conditions during actual CPR, we aimed to predict rib fatigue fractures under conditions simulating real-life scenarios by analyzing the sensitivity and interrelation of chest compression conditions on the model's fatigue life. Time constraints led to the selection of optimal analysis conditions through the use of design of experiments (DOE), specifically orthogonal array testing, followed by the construction of a deep learning-based metamodel. The predicted fatigue life values of the rib cage model, obtained from the metamodel, showed the influence of the four explanatory variables on fatigue life. These results may be used to devise safer CPR guidelines, particularly for the elderly at a high risk of acute cardiac arrest, safeguarding against potential complications like fatigue fractures.

Effect of a backboard on chest compression quality during in-hospital adult cardiopulmonary resuscitation: A randomised, single-blind, controlled trial using a manikin model

INTRODUCTION

Chest compression quality during in-hospital resuscitation is often suboptimal on a soft surface. Scientific evidence regarding the effectiveness of a backboard is scarce. This single-blinded manikin study evaluated the effect of a backboard on compression depth, rate and chest recoil performed by nurses. Sex, BMI, age and clinical department were considered as potential predictors.

METHODS

Using self-learning, nurses were retrained to achieve a minimal combined compression score at baseline. This combined score consisted of ≥70% compressions with depth 50-60 mm, ≥70% compressions with complete release (≤5mm) and a mean compression rate of 100-120 bpm. Subsequently, nurses were allocated to a backboard or control group and performed a two-minute cardiopulmonary resuscitation test. The main outcome measure was the difference in proportion of participants achieving a combined compression score of ≥70%.

RESULTS

In total 278 nurses were retrained, 158 nurses dropped out and 120 were allocated to the backboard (n = 61) or control group (n = 59). The proportion of participants achieving a combined compression score of ≥70% was not significantly different (p = 0.475) and suboptimal in both groups: backboard group 47.5% (backboard) versus 41.0% (control). Older age (≥51 years) was associated with a lower probability of achieving a combined compression score >70% [OR = 0.133; 95% confidence interval (CI), 0.037-0.479; p = 0.002].

CONCLUSION

Using a backboard did not significantly improve compression quality in our study. Important decay of compression skills was observed in both groups, highlighting the importance of frequent retraining, particularly in some age groups.

Use of backboards in cardiopulmonary resuscitation: a systematic review and meta-analysis

To achieve optimal chest compression depth, victims of cardiac arrest should be placed on a firm surface. Backboards are usually placed between the mattress and the back of a patient in the attempt to increase cardiopulmonary resuscitation (CPR) quality, but their effectiveness remains controversial. A systematic search was performed to include studies on humans and simulation manikins assessing CPR quality with or without backboards. The primary outcome of the meta-analysis was the difference in chest compression depth between these two conditions. Out of 557 records, 16 studies were included in the review and all were performed on manikins. The meta-analysis, performed on 15 articles, showed that the use of backboards during CPR increases chest compression depth by 1.46 mm in manikins. Despite statistically significant, this increase could have a limited clinical impact on CPR, due to the substantial heterogeneity of experimental conditions and the scarcity of other CPR quality indicators.

Impacto das superfícies de compressão na massagem cardíaca durante a reanimação cardiopulmonar: uma revisão integrativa

Resumo Objetivo sintetizar as evidências disponíveis na literatura sobre os tipos de superfícies de compressão utilizadas na RCP e analisar quais características das superfícies de compressão têm impacto na eficácia da compressão torácica durante a RCP. Método revisão integrativa da literatura, cujos critérios de seleção e inclusão foram: artigos completos, em inglês, português ou espanhol e que respondessem a seguinte questão de pesquisa: “Quais são as características das superfícies de compressão que têm impacto na eficácia das compressões torácicas durante a RCP?”. Realizada entre os meses de junho e julho de 2019. Resultados inclui-se 12 artigos de estudos experimentais, cuja extração de dados revelou 13 tipos diferentes de colchões. Em relação às pranchas, seis tamanhos diferentes foram relatados, com diferentes materiais. Constatou-se influências do tipo de superfície de compressão na força necessária para realizar as compressões torácicas. Conclusão as evidências apontam que colchões de maiores dimensões e com tecnologia para redução de pressão e camas mais largas apresentam impactos negativos na qualidade das compressões torácicas. Implicação para prática o conhecimento sobre a influência do tipo e características das superfícies de apoio na qualidade das compressões torácicas podem subsidiar profissionais na escolha e incorporação de tecnologias no ambiente hospitalar.

Adult Basic Life Support: International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations

This 2020 International Consensus on Cardiopulmonary Resuscitation (CPR) and Emergency Cardiovascular Care Science With Treatment Recommendations on basic life support summarizes evidence evaluations performed for 20 topics that were prioritized by the Basic Life Support Task Force of the International Liaison Committee on Resuscitation. The evidence reviews include 16 systematic reviews, 3 scoping reviews, and 1 evidence update. Per agreement within the International Liaison Committee on Resuscitation, new or revised treatment recommendations were only made after a systematic review.

Systematic reviews were performed for the following topics: dispatch diagnosis of cardiac arrest, use of a firm surface for CPR, sequence for starting CPR (compressions-airway-breaths versus airway-breaths-compressions), CPR before calling for help, duration of CPR cycles, hand position during compressions, rhythm check timing, feedback for CPR quality, alternative techniques, public access automated external defibrillator programs, analysis of rhythm during chest compressions, CPR before defibrillation, removal of foreign-body airway obstruction, resuscitation care for suspected opioid-associated emergencies, drowning, and harm from CPR to victims not in cardiac arrest.

The topics that resulted in the most extensive task force discussions included CPR during transport, CPR before calling for help, resuscitation care for suspected opioid-associated emergencies, feedback for CPR quality, and analysis of rhythm during chest compressions. After discussion of the scoping reviews and the evidence update, the task force prioritized several topics for new systematic reviews.

Adult Basic Life Support: 2020 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations

This2020 International Consensus on Cardiopulmonary Resuscitation(CPR)and Emergency Cardiovascular Care Science With Treatment Recommendationson basic life support summarizes evidence evaluations performed for 22 topics that were prioritized by the Basic Life Support Task Force of the International Liaison Committee on Resuscitation. The evidence reviews include 16 systematic reviews, 5 scoping reviews, and 1 evidence update. Per agreement within the International Liaison Committee on Resuscitation, new or revised treatment recommendations were only made after a systematic review.

Systematic reviews were performed for the following topics: dispatch diagnosis of cardiac arrest, use of a firm surface for CPR, sequence for starting CPR (compressions-airway-breaths versus airway-breaths-compressions), CPR before calling for help, duration of CPR cycles, hand position during compressions, rhythm check timing, feedback for CPR quality, alternative techniques, public access automated external defibrillator programs, analysis of rhythm during chest compressions, CPR before defibrillation, removal of foreign-body airway obstruction, resuscitation care for suspected opioid-associated emergencies, drowning, and harm from CPR to victims not in cardiac arrest.

The topics that resulted in the most extensive task force discussions included CPR during transport, CPR before calling for help, resuscitation care for suspected opioid-associated emergencies, feedback for CPR quality, and analysis of rhythm during chest compressions. After discussion of the scoping reviews and the evidence update, the task force prioritized several topics for new systematic reviews.

Effect of using a home-bed mattress on bystander chest compression during out-of-hospital cardiac arrest

Background:

Bystander cardiopulmonary resuscitation is a key component of life-saving after an out-of-hospital cardiac arrest. In the pre-arrival instructions for out-of-hospital cardiac arrest, it is recommended that the patient be laid on a flat floor. However, the most common reason for not performing cardiopulmonary resuscitation is that the bystander could not move the patient.

Objectives:

This study aim to investigate the effects of using a home-bed mattress on the quality of chest compression.

Methods:

In this prospective, randomized study, chest compression without ventilation was performed for 4 min on a Resusci Anne manikin placed on a flat floor or on three types of home-bed mattresses (hard, medium and soft). Chest compression depth, chest compression rate and chest recoil were measured from the manikin with the Laerdal PC Skill Reporting System, and changes in chest compression quality using the four different surfaces were compared.

Results:

Thirty participants were enrolled to perform chest compression. There was no significant difference in chest compression depth and depth accuracy between the four surfaces. The median chest compression rates were 108.1 ± 8.5, 107.0 ± 8.3, 103.3 ± 8.9 and 98.3 ± 7.9 compressions/min ( p < 0.001) for the flat floor, hard-, medium-, and soft-firmness mattresses, respectively. Moreover, there was no a significant difference in chest recoil accuracy.

Conclusion:

Using a home-bed mattress did not decrease the chest compression quality, except chest compression rate of soft-firmness mattress. Thus, it may be effective to initiate chest compression on a home-bed mattress if the bystander cannot move the patient to the floor.

Effect of Emergency Department Mattress Compressibility on Chest Compression Depth Using a Standardized Cardiopulmonary Resuscitation Board, a Slider Transfer Board, and a Flat Spine Board: A Simulation-Based Study

INTRODUCTION

Cardiopulmonary resuscitation (CPR) performed on a mattress decreases effective chest compression depth. Using a CPR board partially attenuates mattress compressibility. We aimed to determine the effect of a CPR board, a slider transfer board, a CPR board with a slider transfer board, and a flat spine board on chest compression depth with a mannequin placed on an emergency department mattress.

METHODS

The study used a cross-over study design. The CPR-certified healthcare providers performed 2 minutes of compressions on a mannequin in five conditions, an emergency department mattress with: (a) no hard surface, (b) a CPR board, (c) a slider transfer board, (d) a CPR board and slider transfer board, and (e) a flat spine board. Compression depths were measured from two sources for each condition: (a) an internal device measuring sternum-to-spine compression and (b) an external device measuring sternum-to-spine compression plus mattress compression. The difference of the two measures (ie, depleted compression depth) was summarized and compared between conditions.

RESULTS

A total of 10,203 individual compressions from 10 participants were analyzed. The mean depleted compression depths (percentage depletion) secondary to mattress effect were the following: 23.6 mm (29.7%) on a mattress only, 13.7 mm (19.5%) on a CPR board, 16.9 mm (23.1%) on a slider transfer board, 11.9 mm (17.3%) on a slider transfer board plus backboard, and 10.3 mm (15.4%) on a flat spine board. The differences in percentage depletion across conditions were statistically significant.

CONCLUSION

Cardiopulmonary resuscitation providers should use a CPR board and slider transfer board or a flat spine board alone because these conditions are associated with the smallest amount of mattress compressibility.

Does the Bed Frame Deflection Occur along with Mattress Deflection during In-Hospital Cardiopulmonary Resuscitation? an Experiment Using Mechanical Devices

Objectives

When we perform chest compression on a patient on a bed, the mattress and bed frame can be depressed together with the patient's chest. This study was conducted to assess whether bed frame deflection occurred during chest compressions.

Methods

We designed a firm bed (“bed like the ground,” BLG) to assess the bed frame deflection in the Stryker Trauma Stretcher (STS) and the ER stretcher cart (ER-SC). The STS included a soft mattress and the ER-SC a hard mattress. We performed 50 continuous chest compressions on the Resusci Anne Skill Reporter with CPRmeter in each experiment. The experiments were done in four settings. Test 1 included the BLG; test 2 included a mattress and backboard on each bed; test 3 included the mattress of each bed and a backboard on the BLG; and test 4 included the mattress of each bed on the BLG. We calculated the mattress and bed frame deflections using the gaps of compression depths between the values measured by Resusci Anne and CPRmeter.

Results

The mattress deflections of the STS and ER-SC mattress were determined to be 11.2 and 0.67 mm, respectively. The bed frame deflection for the STS and ER-SC were 0.95 and 5.17 mm, respectively.

Conclusion

The study confirms that bed frame deflection will occur when we perform chest compressions on the manikin lying on a bed. Additionally, the bed frame deflections differ depending on the type of bed. (Hong Kong j.emerg.med. 2016;23:35-41)

Reducing the impact of intensive care unit mattress compressibility during CPR: a simulation-based study

BACKGROUND

The depth of chest compression (CC) during cardiac arrest is associated with patient survival and good neurological outcomes. Previous studies showed that mattress compression can alter the amount of CCs given with adequate depth. We aim to quantify the amount of mattress compressibility on two types of ICU mattresses and explore the effect of memory foam mattress use and a backboard on mattress compression depth and effect of feedback source on effective compression depth.

METHODS

The study utilizes a cross-sectional self-control study design. Participants working in the pediatric intensive care unit (PICU) performed 1 min of CC on a manikin in each of the following four conditions: (i) typical ICU mattress; (ii) typical ICU mattress with a CPR backboard; (iii) memory foam ICU mattress; and (iv) memory foam ICU mattress with a CPR backboard, using two different sources of real-time feedback: (a) external accelerometer sensor device measuring total compression depth and (b) internal light sensor measuring effective compression depth only. CPR quality was concurrently measured by these two devices. The differences of the two measures (mattress compression depth) were summarized and compared using multilevel linear regression models. Effective compression depths with different sources of feedback were compared with a multilevel linear regression model.

RESULTS

The mean mattress compression depth varied from 24.6 to 47.7 mm, with percentage of depletion from 31.2 to 47.5%. Both use of memory foam mattress (mean difference, MD 11.7 mm, 95%CI 4.8-18.5 mm) and use of backboard (MD 11.6 mm, 95% CI 9.0-14.3 mm) significantly minimized the mattress compressibility. Use of internal light sensor as source of feedback improved effective CC depth by 7-14 mm, compared with external accelerometer sensor.

CONCLUSION

Use of a memory foam mattress and CPR backboard minimizes mattress compressibility, but depletion of compression depth is still substantial. A feedback device measuring sternum-to-spine displacement can significantly improve effective compression depth on a mattress.

TRIAL REGISTRATION

Not applicable. This is a mannequin-based simulation research.

Smartwatches as chest compression feedback devices: A feasibility study

BACKGROUND

Recently, there have been attempts to use smartphones and smartwatches as the feedback devices to improve the quality of chest compressions. In this study, we compared chest compression depth feedback accuracy between a smartphone and a smartwatch in a hands-only cardiopulmonary resuscitation scenario, using a manikin with a displacement sensor system.

METHODS

Ten basic life support providers participated in this study. Guided by the chest compression depths displayed on the monitor of a laptop, which received data from the manikin, each participant performed 2min of chest compressions for each target depth (35mm and 55mm) on a manikin while gripping a smartphone and wearing a smartwatch. Participants had a rest of 1h between the instances, and the first target depth was set at random. Each chest compression depth data value from the smartphone and smartwatch and a corresponding reference value from the manikin with the displacement system were recorded. To compare the accuracy between the smartphone and smartwatch, the errors, expressed as the absolute of the differences between the reference and each device, were calculated.

RESULTS

At both target depths, the error of the smartwatch were significantly smaller than that of the smartphone (the errors of the smartphone vs. smartwatch at 35mm: 3.4 (1.3) vs. 2.1 (0.8) mm; p=0.008; at 55mm: 5.3 (2.8) vs. 2.3 (0.9) mm; p=0.023).

CONCLUSION

The smartwatch-based chest compression depth feedback was more accurate than smartphone-based feedback.

Training a Chest Compression of 6-7 cm Depth for High Quality Cardiopulmonary Resuscitation in Hospital Setting: A Randomised Controlled Trial

PURPOSE

During cardiopulmonary resuscitation (CPR), chest compression (CC) depth is influenced by the surface on which the patient is placed. We hypothesized that training healthcare providers to perform a CC depth of 6-7 cm (instead of 5-6 cm) on a manikin placed on a mattress during CPR in the hospital might improve their proper CC depth.

MATERIALS AND METHODS

This prospective randomised controlled study involved 66 premedical students without CPR training. The control group was trained to use a CC depth of 5-6 cm (G 5-6), while the experimental group was taught to use a CC depth of 6-7 cm (G 6-7) with a manikin on the floor. All participants performed CCs for 2 min on a manikin that was placed on a bed 1 hour and then again 4 weeks after the training without a feedback. The parameters of CC quality (depth, rate, % of accurate depth) were assessed and compared between the 2 groups.

RESULTS

Four students were excluded due to loss to follow-up and recording errors, and data of 62 were analysed. CC depth and % of accurate depth were significantly higher among students in the G 6-7 than G 5-6 both 1 hour and 4 weeks after the training (p<0.001), whereas CC rate was not different between two groups (p>0.05).

CONCLUSION

Training healthcare providers to perform a CC depth of 6-7 cm could improve quality CC depth when performing CCs on patients who are placed on a mattress during CPR in a hospital setting.

Performance of different support surfaces during experimental resuscitation (CPR)

The relationship between the efficacy of resuscitation and the mattresses and backboards used in acute care units, has been studied previously. However, few reports focus on the relative efficacy of resuscitation when using mattresses with different modes of function. This study examines the performance of different support surfaces during experimental cardiopulmonary resuscitation (CPR). The surfaces included a hard surface, a higher specification foam mattress, a dynamic, alternating pressure mattress, and a dynamic, reactive minimum pressure air mattress system. A pressure sensitive mat was placed between the mattresses and each surface and the efficacy of resuscitation measured using differences in compression frequency, compression depth and hands-on time. Our results suggest that the efficacy of resuscitation is dependent on the mode of action of the mattress, while adequate compression frequency and depth do not have a significant effect. In the open system alternating mattress, deflation of the mattress using the CPR function improved the stability of the resuscitation in our study, especially in situations where the height of the air mattress is greater than 20–25 centimeters. Using our experimental system, resuscitation on a closed air system mattress optimally combined stability and effort, while the CPR function converts the air system of the mattress to open, which impairs its functionality during resuscitation. These results indicate that resuscitation is dependent of the mode of action of the mattress and whether the mattress-specific CPR function was used or not. However, the interactions are complex and are dependent on the interaction between the body and the mattress, i.e. its immersion and envelopment properties. Furthermore, this study casts doubt on the necessity of the CPR function in air mattresses.

Manual versus Mechanical Chest Compressions on Surfaces of Varying Softness with or without Backboards: A Randomized, Crossover Manikin Study

BACKGROUND

Chest compression quality is decisive for overall outcome after cardiac arrest. Chest compression depth may decrease when cardiopulmonary resuscitation (CPR) is performed on a mattress, and the use of a backboard does not necessarily improve compression depth. Mechanical chest compression devices may overcome this problem.

OBJECTIVES

We sought to investigate the effectiveness of manual chest compressions both with and without a backboard compared to mechanical CPR performed on surfaces of different softness.

METHODS

Twenty-four advanced life support (ALS)-certified rescuers were enrolled. LUCAS2 (Physio-Control, Redmond, WA) delivers 52 ± 2 mm deep chest compressions and active decompressions back to the neutral position (frequency 102 min(-1); duty cycle, 50%). This simulated CPR scenario was performed on a Resusci-Anne manikin (Laerdal, Stavanger, Norway) that was lying on 3 different surfaces: 1) a concrete floor, 2) a firm standard mattress, and 3) a pressure-relieving mattress. Data were recorded by the Laerdal Skill Reporting System.

RESULTS

Manual chest compression with or without a backboard were performed correctly less often than mechanical chest compressions (floor: 33% [interquartile range {IQR}, 27-48%] vs. 90% [IQR, 86-94%], p < 0.001; standard mattress: 32% [IQR, 20-45%] vs. 27% [IQR, 14-46%] vs. 91% [IQR, 51-94%], p < 0.001; and pressure-relieving mattress 29% [IQR, 17-49%] vs. 30% [IQR, 17-52%] vs. 91% [IQR, 87-95%], p < 0.001). The mean compression depth on both mattresses was deeper with mechanical chest compressions (floor: 53 mm [range, 47-57 mm] vs. 56 mm [range, 54-57 mm], p = 0.003; standard mattress: 50 mm [range, 44-55 mm] vs. 51 mm [range, 47-55 mm] vs. 55 mm [range, 54-58 mm], p < 0.001; and pressure-relieving mattress: 49 mm [range, 44-55 mm] vs. 50 mm [range, 44-53 mm] vs. 55 mm [range, 55-56 mm], p < 0.001). In this ∼6-min scenario, the mean hands-off time was ∼15 to 20 s shorter in the manual CPR scenarios.

CONCLUSIONS

In this experimental study, only ∼30% of manual chest compressions were performed correctly compared to ∼90% of mechanical chest compressions, regardless of the underlying surface. Backboard use did not influence the mean compression depth during manual CPR. Chest compressions were deeper with mechanical CPR. The mean hands-off time was shorter with manual CPR.

50% duty cycle may be inappropriate to achieve a sufficient chest compression depth when cardiopulmonary resuscitation is performed by female or light rescuers

OBJECTIVE

Current guidelines for cardiopulmonary resuscitation recommend chest compressions (CC) during 50% of the duty cycle (DC) in part because of the ease with which individuals may learn to achieve it with practice. However, no consideration has been given to a possible interaction between DC and depth of CC, which has been the subject of recent study. Our aim was to determine if 50% DC is inappropriate to achieve sufficient chest compression depth for female and light rescuers.

METHODS

Previously collected CC data, performed by senior medical students guided by metronome sounds with various down-stroke patterns and rates, were included in the analysis. Multiple linear regression analysis was performed to determine the association between average compression depth (ACD) with average compression rate (ACR), DC, and physical characteristics of the performers. Expected ACD was calculated for various settings.

RESULTS

DC, ACR, body weight, male sex, and self-assessed physical strength were significantly associated with ACD in multivariate analysis. Based on our calculations, with 50% of DC, only men with ACR of 140/min or faster or body weight over 74 kg with ACR of 120/min can achieve sufficient ACD.

CONCLUSION

A shorter DC is independently correlated with deeper CC during simulated cardiopulmonary resuscitation. The optimal DC recommended in current guidelines may be inappropriate for achieving sufficient CD, especially for female or lighter-weight rescuers.

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.

Development of a smart backboard system for real-time feedback during CPR chest compression on a soft back support surface

The quality of cardiopulmonary resuscitation (CPR) is often inconsistent and frequently fails to meet recommended guidelines. One promising approach to address this problem is for clinicians to use an active feedback device during CPR. However, one major deficiency of existing feedback systems is that they fail to account for the displacement of the back support surface during chest compression (CC), which can be important when CPR is performed on a soft surface. In this study we present the development of a real-time CPR feedback system based on an algorithm which uses force and dual-accelerometer measurements to provide accurate estimation of the CC depth on a soft surface, without assuming full chest decompression. Based on adult CPR manikin tests it was found that the accuracy of the estimated CC depth for a dual accelerometer feedback system is significantly better (7.3% vs. 24.4%) than for a single accelerometer system on soft back support surfaces, in the absence or presence of a backboard. In conclusion, the algorithm used was found to be suitable for a real-time, dual accelerometer CPR feedback application since it yielded reasonable accuracy in terms of CC depth estimation, even when used on a soft back support surface.

Optimal chest compression in cardiopulmonary resuscitation depends upon thoracic and back support stiffness

A biomechanical analysis of the constant peak displacement and constant peak force methods of cardiopulmonary resuscitation (CPR) has revealed that optimal CC performance strongly depends on back support stiffness, CC rate, and the thoracic stiffness of the patient being resuscitated. Clinically the results presented in this study suggest that the stiffness of the back support surfaces found in many hospitals may be sub-optimal and that a backboard or a concrete floor can be used to enhance CC effectiveness. In addition, the choice of optimal CC rate and maximum sternal force applied by clinicians during peak force CPR is ought to be based on a general assessment of the patient's thoracic stiffness, taking into account the patient's age, gender, and physical condition; which is consistent with current clinical practice. In addition, it is important for clinicians to note that very high peak sternal forces, exceeding the limit above which severe chest wall trauma and abdominal injury occurs, may be required for optimal CC during peak force CPR on patients with very stiff chests. In these cases an alternative CPR technique may be more appropriate.

Backboards are important when chest compressions are provided on a soft mattress

AIM

Determine the impact of backboard placement, torso weight and bed compression on chest compression (CC) depth feedback in simulated cardiac arrest patients.

METHODS

Epochs of 50 high quality CCs with real-time feedback of sternum-to-spine compression depth were provided by a blinded BLS/ACLS/PALS certified provider on manikins of two torso weights (25 vs. 50 kg), using three bed surfaces (stretcher, Stryker hospital bed with Impression mattress, soft Total Care ICU bed), with/without a backboard (BB). Two BB sizes were tested (small: 60 cm × 50 cm; large: 89 cm × 50 cm) in vertical vs. horizontal orientation. Mattress displacement was measured using an accelerometer placed internally on the spine plate of the manikin. Mattress displacement of ≥ 5 mm was prospectively defined as the minimal clinically important difference.

RESULTS

During CPR (CC depth: 51.8 ± 2.8mm), BB use significantly reduced mattress displacement only for soft ICU beds. Mattress displacement was reduced (vs. no BB) for 25 kg torso weight: small BB12.3mm (95%CI 11.9-12.6), horizontally oriented large BB 11.2mm (95%CI 10.8-11.7), and vertically oriented large BB 12.2mm (95%CI 11.8-12.6), and for 50 kg torso weight: small BB 7.4mm (95%CI 7.1-7.8), horizontally oriented large BB 7.9 mm (95%CI 7.6-8.3), and vertically oriented large BB 6.2mm (95%CI 5.8-6.5; all p<0.001). BB size and orientation did not significantly affect mattress displacement. Lighter torso weight was associated with larger displacement in soft ICU beds without BB (difference: 6.9 mm, p<0.001).

CONCLUSION

BB is important for CPR when performed on soft surfaces, such as ICU beds, especially when torso weight is light. BB may not be needed on stretchers, relatively firm hospital beds, or for patients with heavy torso weights.

Induction of a shorter compression phase is correlated with a deeper chest compression during metronome-guided cardiopulmonary resuscitation: a manikin study

OBJECTIVES

Recent studies have shown that there may be an interaction between duty cycle and other factors related to the quality of chest compression. Duty cycle represents the fraction of compression phase. We aimed to investigate the effect of shorter compression phase on average chest compression depth during metronome-guided cardiopulmonary resuscitation.

METHODS

Senior medical students performed 12 sets of chest compressions following the guiding sounds, with three down-stroke patterns (normal, fast and very fast) and four rates (80, 100, 120 and 140 compressions/min) in random sequence. Repeated-measures analysis of variance was used to compare the average chest compression depth and duty cycle among the trials.

RESULTS

The average chest compression depth increased and the duty cycle decreased in a linear fashion as the down-stroke pattern shifted from normal to very fast (p<0.001 for both). Linear increase of average chest compression depth following the increase of the rate of chest compression was observed only with normal down-stroke pattern (p=0.004).

CONCLUSIONS

Induction of a shorter compression phase is correlated with a deeper chest compression during metronome-guided cardiopulmonary resuscitation.