The impact of compliant surfaces on in-hospital chest compressions: effects of common mattresses and a backboard

Cardiopulmonary Resuscitation: The Importance of the Basics

Cardiac arrest is the loss of organized cardiac activity. Unfortunately, survival to hospital discharge is poor, despite recent scientific advances. The goals of cardiopulmonary resuscitation (CPR) are to restore circulation and identify and correct an underlying etiology. High-quality compressions remain the foundation of CPR, optimizing coronary and cerebral perfusion pressure. High-quality compressions must be performed at the appropriate rate and depth. Interruptions in compressions are detrimental to management. Mechanical compression devices are not associated with improved outcomes but can assist in several situations.

Can support surfaces characteristics influence high-quality chest compression? manikin experiment with a mechanical device

BACKGROUND

Support surfaces variables, such as size, material, and density, can determine chest compression depth in cardiopulmonary resuscitation.

OBJECTIVE

to analyze the force required to do a high-quality chest compression concerning different surfaces in CPR.

METHOD

This experimental study was developed using a Little Anne manikin and a mechanical device to perform chest compressions. Nine sets of surfaces were tested and compared to a control.

RESULTS

230 experimental tests were done in sets of bed or stretcher + mattress and presence or absence of different backboards. In the control condition, the average force to reach 5 cm of depth was 42.14±0.97 (kgf). Set 9, compatible with a narrow stretcher with a thin mattress, had the best surfaces to reach recommended depth, with or without a backboard. All other sets required significantly more force for high-quality chest compression. Regression analysis confirms that backboard size is not significant for the force for high-quality chest compression.

CONCLUSION

There is an association of dimensions and types of beds or stretchers and mattresses with a force increase. Type and dimensions of the backboard are not relevant for the force required, regardless of the characteristics of the set of the bed or stretcher and mattress.

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.

Sports safety matting diminishes cardiopulmonary resuscitation quality and increases rescuer perceived exertion

OBJECTIVES

Compliant surfaces beneath a casualty diminish the quality of cardiopulmonary resuscitation (CPR) in clinical environments. To examine this issue in a sporting environment, we assessed chest compression quality and rescuer exertion upon compliant sports safety matting.

METHODS

Twenty-seven advanced life support providers volunteered (13 male/14 female; mass = 79.0 ± 12.5 kg; stature = 1.77 ± 0.09 m). Participants performed 5 × 2 min, randomized bouts of continuous chest compressions on a mannequin, upon five surfaces: solid floor; low-compliance matting; low-compliance matting with a backboard; high-compliance matting; high-compliance matting with a backboard. Measures included chest compression depth and rate, percentage of adequate compressions, and rescuer heart rate and perceived exertion.

RESULTS

Chest compression depth and rate were significantly lower upon high-compliance matting relative to other surfaces (p<0.05). The percentage of adequate compressions (depth ≥50 mm) was lowest upon high-compliance matting (40 ± 39%) versus low-compliance matting (60 ± 36%) and low-compliance matting with a backboard (59 ± 39%). Perceived exertion was significantly greater upon high-compliance matting versus floor, low-compliance matting, and low-compliance matting with a backboard (p<0.05).

CONCLUSION

Providers of CPR should be alerted to the detrimental effects of compliant safety matting in a sporting environment and prepare to alter the targeted compression depth and rescuer rotation intervals accordingly.

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.

Effect of a dynamic mattress on chest compression quality during cardiopulmonary resuscitation

BACKGROUND

In-hospital cardiac arrest is a medical emergency that occurs on a regular basis. As patients most at risk for an in-hospital cardiac arrest are usually positioned on a dynamic mattress, it is important to measure the effect of mattress compressibility on chest compression quality during cardiopulmonary resuscitation (CPR). High-quality CPR is essential for patient survival and good neurological outcome.

AIMS AND OBJECTIVES

To examine the effect of an inflated dynamic overlay mattress on chest compression quality during CPR and to explore the predictive effect of health care providers' anthropometric factors, hand positioning and mattress type on chest compression frequency and depth.

DESIGN

Manikin-based single-blinded randomised controlled trial.

METHODS

Nursing students (N = 70) were randomised to a control (viscoelastic foam mattress) or intervention group (inflated dynamic overlay mattress on top of a viscoelastic foam mattress) and had to perform chest compressions over a 2-minute period. Compression rate, depth and hand positioning were registered. The 2015 European Resuscitation Council (ERC) guidelines were used as a reference.

RESULTS

The mean difference in chest compression depth between control and intervention groups was 2.86 mm (P = .043). Both groups met the guidelines for adequate chest compression quality, as recommended by the ERC. A predictive effect of health care providers' body height and weight, mattress type and hand positioning on compression depth could be demonstrated (P = .004).

CONCLUSIONS

CPR in bedridden patients on a dynamic overlay mattress has a negative effect on the quality of chest compressions. Mean chest compression depth decreases significantly. However, clinical significance of the results may be debatable. Mattress type, body weight and hand positioning appear to be significant predictors for adequate chest compression depth.

RELEVANCE TO CLINICAL PRACTICE

A firm surface under the patient is needed during CPR. Special attention must be paid to correct hand positioning during CPR.

Chest stiffness dynamics in extended continuous compressions cardiopulmonary resuscitation

AIM OF THE STUDY

To characterize the effects of extended duration continuous compressions cardiopulmonary resuscitation (CPR) on chest stiffness, and its association with adherence to CPR guidelines.

METHODS

Records of force and acceleration were extracted from CPR monitors used during attempts of resuscitation from out-of-hospital cardiac arrest. Cases of patients receiving at least 1000 compressions were selected for analysis to focus on extended CPR efforts. Stiffness was normalized per patient to their initial stiffness. Force remaining at the end of compression was used to identify complete release. Non-parametric statistical methods were used throughout as underlying distributions of all types of measurements were non-Gaussian. Averages are reported as median (interquartile range).

RESULTS

More than 1000 chest compressions were delivered in 471 of 703 cases. Rate of change in normalized stiffness (S_n) was unrelated to patient age, sex or initial ECG rhythm, and did not predict survival. Most (76%) chests became less stiff over the course of resuscitation efforts. While the remainder (24%) exhibited increased stiffness, overall S_n decreased monotonically, declining by 31% through 3500 compressions. Rate adherence did not show a consistent trend with S_n. Depth adherence and complete release improved modestly with decreasing S_n.

CONCLUSION

Chest compressions during extended CPR reduced the stiffness of most patients' chests, in the aggregate by 31% after 3500 compressions. This softening was associated with modestly improved adherence to depth and release guidelines, with inconsistent relation to rate adherence to guidelines.

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.

Real-Time Cardiopulmonary Resuscitation Feedback and Targeted Training Improve Chest Compression Performance in a Cohort of International Healthcare Providers

BACKGROUND

Optimal cardiopulmonary resuscitation (CPR) performance is the foundation of successful cardiac arrest resuscitation. However, health care providers perform inadequate compressions. Better training techniques and real-time CPR feedback may improve compression performance.

OBJECTIVE

We sought to evaluate the impact of a targeted training program combined with real-time defibrillator CPR feedback on chest compression performance in an international cohort of health care providers.

METHODS

Physicians, nurses, respiratory therapists, and technicians from 6 hospitals in 5 countries (Taiwan, Singapore, China, Bahrain, and Kuwait) participated in a standardized resuscitation workshop. Chest compression was measured before and after didactics and activation of CPR feedback. Compressions were performed for 1 min on standard CPR manikins placed on a hospital bed and backboard and measured using ZOLL R Series defibrillators. The percentage of compressions meeting target values for depth and rate were compared before and after the workshop and activation of real-time CPR feedback. No depth maximum was defined to allow for mattress compression.

RESULTS

Chest compressions were more likely to meet targets for depth (71-95%, odds ratio [OR] 8.61 [95% confidence interval {CI} 4.42-16.77], p < 0.001), rate (41-81%, OR 6.4 [95% CI 4.2-9.8], p < 0.001), and both depth and rate (5-42%, OR 2.4 [95% CI 6.7-22.9], p < 0.001) after the workshop and activation of real-time CPR feedback.

CONCLUSIONS

A targeted training intervention combined with real-time CPR feedback improved chest compression performance among health care providers from various countries.

The impact of real-time chest compression feedback increases with application of the 2015 guidelines

BACKGROUND

Cardiac arrest survival depends upon chest compression quality. Real-time audiovisual feedback may improve compression guideline adherence, particularly with the more specific 2015 guidelines.

METHODS

Subjects included healthcare providers from multiple U.S. hospitals. Compression rate and depth were recorded using standard manikins and real-time audiovisual feedback defibrillators (ZOLL R Series). Subjects were enrolled before (n = 756) and after (n = 995) release of the 2015 guidelines, which define narrower compression targets. Subjects performed 2 min of continuous compressions before and after activation of feedback. The percentage of compressions meeting appropriate rate/depth targets was determined before and after release of the 2015 guidelines.

RESULTS

An increase in compression guideline adherence was observed with use of feedback before [68.7% to 96.3%, p < .001] and after [16.6% to 94.1%, p < .001] release of the 2015 guidelines. The proportion of subjects requiring feedback to achieve adherence was higher for the 2015 guidelines [28.6% vs. 78.5%, OR 9.12, 95% CI 7.33-11.35, p < .001].

CONCLUSIONS

The use of real-time audiovisual feedback increases adherence to chest compression guidelines, particularly with application of the narrower 2015 guidelines targets for compression depth and rate.

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.

The Impact of Backboard Placement on Chest Compression Quality: A Mannequin Study

Introduction:

High-quality chest compressions (CCs) are associated with high survival rates and good neurological outcomes in cardiac arrest patients. The 2015 American Heart Association (AHA; Dallas, Texas USA) Guidelines for Resuscitation defined and recommended high-quality CCs during cardiopulmonary resuscitation (CPR). However, CPR providers struggle to achieve high-quality CCs. There is a debate about the use of backboards during CPR in literature. Some studies suggest backboards improve CC quality, whereas others suggest that backboards can cause delays. This is the first study to evaluate all three components of high-quality CCs: compression depth, recoil depth, and rate, at the same time with a high number of subjects. This study evaluated the impact of backboards on CC quality during CPR. The primary outcome was the difference in successful CC rates between two groups.

Methods:

This was a randomized, controlled, single-blinded study using a high-fidelity mannequin. The successful CC rates, means CC depths, recoil depths, and rates achieved by 6th-grade undergraduate medical students during two minutes of CPR were compared between two randomized groups: an experimental group (backboard present) and a control group (no backboard).

Results:

Fifty-one of all 101 subjects (50.5%) were female, and the mean age was 23.9 (SD = 1.01) years. The number and the proportion of successful CCs were significantly higher in the experimental group (34; 66.7%) when compared to the control group (19; 38.0%; P = .0041). The difference in mean values of CC depth, recoil depth, and CC rate was significantly higher in the experiment group.

Conclusion:

The results suggest that using a backboard during CPR improves the quality of CCs in accordance with the 2015 AHA Guidelines.

Sanri E, Karacabey S. The impact of backboard placement on chest compression quality: a mannequin study. Prehosp Disaster Med. 2019;34(2):182–187

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.

In a bed or on the floor? - The effect of realistic hospital resuscitation training: A randomised controlled trial

INTRODUCTION

In-hospital cardiac arrest has a poor prognosis and often occurs in patients lying in a hospital bed. A bed mattress is a soft compressible surface that may decrease cardiopulmonary resuscitation (CPR) quality. Often hospital CPR training is performed with a manikin on the floor.

AIM

To study CPR quality following realistic CPR training with a manikin in a bed compared with one on the floor.

METHODS

We conducted a randomised controlled study. Healthcare professionals were randomised to CPR training with a manikin in a hospital bed or one on the floor. Data on CPR quality was collected from manikins. The primary outcome measure was chest compression depth.

RESULTS

In total, 108 healthcare professionals (age: 40years, female: 94%) were included. The mean chest compression depth was 39mm (standard deviation (SD): 10), for the bed group compared with 38mm (SD: 9) for the floor group, p=0.49. A post hoc analysis showed that regardless of the training method, the participants who optimised their working position by jumping onto the bed or lowering the bed had a median chest compression depth of 39mm (25th-75th percentiles: 33-45) compared with 29mm (25th-75th percentiles: 23-41) for participants who did neither, p=0.04.

CONCLUSION

There was no significant difference in chest compression depth between healthcare professionals who trained CPR on a manikin in a hospital bed compared with one on the floor. Chest compression depth was too shallow in both groups. Irrespective of the training method, participants who optimised their working position performed deeper chest compressions.

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.

A Feasibility Study for Measuring Accurate Chest Compression Depth and Rate on Soft Surfaces Using Two Accelerometers and Spectral Analysis

Background. Cardiopulmonary resuscitation (CPR) feedback devices are being increasingly used. However, current accelerometer-based devices overestimate chest displacement when CPR is performed on soft surfaces, which may lead to insufficient compression depth. Aim. To assess the performance of a new algorithm for measuring compression depth and rate based on two accelerometers in a simulated resuscitation scenario. Materials and Methods. Compressions were provided to a manikin on two mattresses, foam and sprung, with and without a backboard. One accelerometer was placed on the chest and the second at the manikin's back. Chest displacement and mattress displacement were calculated from the spectral analysis of the corresponding acceleration every 2 seconds and subtracted to compute the actual sternal-spinal displacement. Compression rate was obtained from the chest acceleration. Results. Median unsigned error in depth was 2.1 mm (4.4%). Error was 2.4 mm in the foam and 1.7 mm in the sprung mattress (p < 0.001). Error was 3.1/2.0 mm and 1.8/1.6 mm with/without backboard for foam and sprung, respectively (p < 0.001). Median error in rate was 0.9 cpm (1.0%), with no significant differences between test conditions. Conclusion. The system provided accurate feedback on chest compression depth and rate on soft surfaces. Our solution compensated mattress displacement, avoiding overestimation of compression depth when CPR is performed on soft surfaces.

Association between chest compression rates and clinical outcomes following in-hospital cardiac arrest at an academic tertiary hospital

AIMS

Recent guidelines for management of cardiac arrest recommend chest compression rates of 100-120 compressions/min. However, animal studies have found cardiac output to increase with rates up to 150 compressions/min. The objective of this study was to test the association between chest compression rates during cardiopulmonary resuscitation for in-hospital cardiac arrest (IHCA) and outcome.

METHODS

We conducted a prospective observational study at a single academic medical center.

INCLUSION CRITERIA

age≥18, IHCA, cardiopulmonary resuscitation performed. We analyzed chest compression rates measured by defibrillation electrodes, which recorded changes in thoracic impedance. The primary outcome was return of spontaneous circulation (ROSC). We used multivariable logistic regression to determine odds ratios for ROSC by chest compression rate categories (100-120, 121-140, >140 compressions/min), adjusted for chest compression fraction (proportion of time chest compressions provided) and other known predictors of outcome. We set 100-120 compressions/min as the reference category for the multivariable model.

RESULTS

We enrolled 222 consecutive patients and found a mean chest compression rate of 139±15. Overall 53% achieved ROSC; among 100-120, 121-140, and >140 compressions/min, ROSC was 29%, 64%, and 49% respectively. A chest compression rate of 121-140 compressions/min had the greatest likelihood of ROSC, odds ratio 4.48 (95% CI 1.42-14.14).

CONCLUSIONS

In this sample of adult IHCA patients, a chest compression rate of 121-140 compressions/min had the highest odds ratio of ROSC. Rates above the currently recommended 100-120 compressions/min may improve the chances of ROSC among IHCA patients.

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.

Cardiac Arrest in Pregnancy

This is the first scientific statement from the American Heart Association on maternal resuscitation. This document will provide readers with up-to-date and comprehensive information, guidelines, and recommendations for all aspects of maternal resuscitation. Maternal resuscitation is an acute event that involves many subspecialties and allied health providers; this document will be relevant to all healthcare providers who are involved in resuscitation and specifically maternal resuscitation.

Simultaneous beat-to-beat assessment of arterial blood pressure and quality of cardiopulmonary resuscitation in out-of-hospital and in-hospital settings

OBJECTIVE

The current recommendation for depth and rate of chest compression (CC) during cardiopulmonary resuscitation (CPR) is based on limited hemodynamic data recorded during human CPR. We have evaluated the possible association between CC depth and rate and continuously measured arterial blood pressure during adult CPR.

METHODS

This prospective study included data from 104 patients resuscitated inside or outside hospital. Adequate data on continuously measured invasive arterial blood pressure (BP) and the quality of CPR from a defibrillator capable recording CPR quality parameters was successful in 39 patients. We used logistic regression and mixed effects modeling to identify CC depths and rates associated with systolic blood pressure (SBP) ≥ 85 mm Hg and diastolic blood pressure (DBP) ≥ 30 mm Hg.

RESULTS

We analyzed 41,575 compression-BP pairs. The values for blood pressure varied greatly between the patients. SBP varied from 25 to 225 mm Hg and DBP from 2 to 59 mm Hg. CC rate 100-120/min and CC depth ≥ 60 mm (without mattress deflection correction) was associated with DBP ≥ 30 mm Hg in both femoral (OR 1.14; 95% CI 1.03, 1.26; p<0.05) and radial (OR 4.70; 95% CI 3.92, 5.63; p<0.001) recordings. For any given subject there was a weak upward trend in blood pressure as CC depth increased.

CONCLUSION

Deeper CC does not equal higher BP in every patient. The heterogeneity of patients creates a challenge to find the optimal way to resuscitate patients individually.

CLINICAL TRIAL REGISTRATION

Clinicaltrials.gov NCT00951704.

2010 American Heart Association recommended compression depths during pediatric in-hospital resuscitations are associated with survival

AIM

Gaps exist in pediatric resuscitation knowledge due to limited data collected during cardiac arrest in real children. The objective of this study was to evaluate the relationship between the 2010 American Heart Association (AHA) recommended chest compression (CC) depth (≥51 mm) and survival following pediatric resuscitation attempts.

METHODS

Single-center prospectively collected and retrospectively analyzed observational study of children (>1 year) who received CCs between October 2006 and September 2013 in the intensive care unit (ICU) or emergency department (ED) at a tertiary care children's hospital. Multivariate logistic regression models controlling for calendar year and known potential confounders were used to estimate the association between 2010 AHA depth compliance and survival outcomes. The primary outcome was 24-h survival. The primary predictor variable was event AHA depth compliance, prospectively defined as an event with ≥60% of 30-s epochs achieving an average CC depth ≥51 mm during the first 5 min of the resuscitation.

RESULTS

There were 89 CC events, 87 with quantitative CPR data collected (23 AHA depth compliant). AHA depth compliant events were associated with improved 24-h survival on both univariate analysis (70% vs. 16%, p<0.001) and after controlling for potential confounders (calendar year of arrest, gender, first documented rhythm; aOR 10.3; CI(95): 2.75-38.8; p<0.001).

CONCLUSIONS

2010 AHA compliant chest compression depths (≥51 mm) are associated with higher 24-h survival compared to shallower chest compression depths, even after accounting for potentially confounding patient and event factors.

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 quality of manual chest compressions during transport--effect of the mattress assessed by dual accelerometers

BACKGROUND

The quality of cardiopulmonary resuscitation (CPR) has an impact on survival. The quality may be impaired if the patient needs to be transported to the hospital with ongoing CPR. The aim of this study was to analyse whether the quality of CPR can be improved during transportation by using real-time audiovisual feedback. In addition, we sought to evaluate the real compression depths taking into account the mattress and stretcher effect.

METHODS

Paramedics (n = 24) performed standard CPR on a Resusci Anne Mannequin in a moving ambulance. Participants were instructed to perform CPR according to European Resuscitation Council Resuscitation guidelines 2010. Each pair acted as their own controls performing CPR first without and then with the feedback device. Compression depth, rate and no-flow fraction and also the mattress effect were recorded by using dual accelerometers by two Philips, HeartStart MRx Q-CPR defibrillators.

RESULTS

In the feedback phase, the mean compression depth increased from 51 (10) to 56 (5) mm (P < 0.001), and the percentage of compression fractions with adequate depth was 60% vs. 89% (P < 0.001). However, taking account of the mattress effect, the real depth was only 41 (8) vs. 44 (5) mm without and with feedback, respectively (P < 0.001). The values for compression rate did not differ.

CONCLUSIONS

CPR quality was good during transportation in general. However, the results suggest that the feedback system improves CPR quality. Dual accelerometer measurements show, on the other hand, that the mattress effect may be a clinically relevant impediment to high quality CPR.

Cardiopulmonary resuscitation quality: [corrected] improving cardiac resuscitation outcomes both inside and outside the hospital: a consensus statement from the American Heart Association

The "2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care" increased the focus on methods to ensure that high-quality cardiopulmonary resuscitation (CPR) is performed in all resuscitation attempts. There are 5 critical components of high-quality CPR: minimize interruptions in chest compressions, provide compressions of adequate rate and depth, avoid leaning between compressions, and avoid excessive ventilation. Although it is clear that high-quality CPR is the primary component in influencing survival from cardiac arrest, there is considerable variation in monitoring, implementation, and quality improvement. As such, CPR quality varies widely between systems and locations. Victims often do not receive high-quality CPR because of provider ambiguity in prioritization of resuscitative efforts during an arrest. This ambiguity also impedes the development of optimal systems of care to increase survival from cardiac arrest. This consensus statement addresses the following key areas of CPR quality for the trained rescuer: metrics of CPR performance; monitoring, feedback, and integration of the patient's response to CPR; team-level logistics to ensure performance of high-quality CPR; and continuous quality improvement on provider, team, and systems levels. Clear definitions of metrics and methods to consistently deliver and improve the quality of CPR will narrow the gap between resuscitation science and the victims, both in and out of the hospital, and lay the foundation for further improvements in the future.

Use of backboard and deflation improve quality of chest compression when cardiopulmonary resuscitation is performed on a typical air inflated mattress configuration

No study has examined the effectiveness of backboards and air deflation for achieving adequate chest compression (CC) depth on air mattresses with the typical configurations seen in intensive care units. To determine this efficacy, we measured mattress compression depth (MCD, mm) on these surfaces using dual accelerometers. Eight cardiopulmonary resuscitation providers performed CCs on manikins lying on 4 different surfaces using a visual feedback system. The surfaces were as follows: A, a bed frame; B, a deflated air mattress placed on top of a foam mattress laid on a bed frame; C, a typical air mattress configuration with an inflated air mattress placed on a foam mattress laid on a bed frame; and D, C with a backboard. Deflation of the air mattress decreased MCD significantly (B; 14.74 ± 1.36 vs C; 30.16 ± 3.96, P < 0.001). The use of a backboard also decreased MCD (C; 30.16 ± 3.96 vs D; 25.46 ± 2.89, P = 0.002). However, deflation of the air mattress decreased MCD more than use of a backboard (B; 14.74 ± 1.36 vs D; 25.46 ± 2.89, P = 0.002). The use of a both a backboard and a deflated air mattress in this configuration reduces MCD and thus helps achieve accurate CC depth during cardiopulmonary resuscitation.

A modeling approach to the effects of force guided versus depth guided compression during cardiopulmonary resuscitation on different chests and back support surfaces

OBJECTIVES

To validate an existing theoretical model for the mechanics of chest compression (CC) during constant peak force cardiopulmonary resuscitation (CPR) using experimental human and manikin CC data from the literature. Also, to gain insights into the clinical application of force guided CPR.

METHODS

The experimental CC data from the literature were analyzed and compared to theoretical predictions from the constant peak force CPR model. The CPR model was also used to explore how CC rate and peak sternal force may influence CC performance during the clinical application of force guided CPR.

RESULTS

The model predictions matched the human CC data to within an average difference of less than 1.5% at CC rates of 60 cpm and 90 cpm, and 0.6% for the manikin data at a CC rate of 90 cpm. The model predictions also showed that the net sternum-to-spine compression depth achieved during force guided CPR strongly depends on the patient's thoracic stiffness.

CONCLUSIONS

Good quantitative agreement between the experimental data from the literature and the theoretical model suggests that the constant peak force CPR model developed by Boe and Babbs provides reasonable prediction of CC mechanics during CPR over a range of clinically relevant CC rates. The model predictions also suggest that the effectiveness of CC during force guided CPR is highly sensitive to the patient's thoracic stiffness and insensitive to the back support stiffness. Patients having high thoracic stiffness (≥ 100 Ncm(-1)) were found to require higher CC forces, which may exceed the force above which severe chest wall trauma and abdominal injury occurs, in order to achieve the ERC recommended CC depth range. This suggests that the choice of maximum sternal force applied by clinicians during constant peak force CPR ought to be based on a general assessment of the patient's thoracic stiffness.

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.

The impact of various backboard configurations on compression stiffness in a manikin study of CPR

When performing cardiopulmonary resuscitation (CPR) it is important that adequate back support is given to the patient in order to allow the medical practitioner to produce an appropriate technique during chest compression (CC). The current study investigates how backboard configuration (i.e., orientation and size) impact compression stiffness during CPR using a torso CPR training manikin. The effect of backboard size on CC performance during CPR was found to be significant with the 94.8% larger backboard producing an increase in compression stiffness of as much as 62.7% relative to the smaller backboard. The impact of backboard orientation was also found to be important with a longitudinal orientation producing an increase in compression stiffness of as much as 60.3% relative to a latitudinal orientation. Backboard configuration should be considered by clinicians when trying to achieve optimal CC performance during CPR in hospital settings.

Comparison of experimental chest compression data to a theoretical model for the mechanics of constant peak displacement cardiopulmonary resuscitation

OBJECTIVES

The objective was to validate an existing theoretical model for the mechanics of constant peak displacement cardiopulmonary resuscitation (CPR) using experimental data taken using various back support surfaces at different chest compression (CC) rates.

METHODS

A CPR simulator was used to perform constant peak displacement CC on a weighted full-body CPR training manikin supported on surfaces of varying stiffness at different CC rates. The net sternum-to-spine displacement, combined chest and mattress displacement, and axial reaction force were measured during each test. The experimental results were compared to theoretical predictions from the constant peak displacement CPR model.

RESULTS

The theoretical model predictions matched the experimental data to within a mean difference of 11.7% at a CC rate of 42 compressions per minute (cpm), 10.0% at a CC rate of 60 cpm, and 10.1% at a CC rate of 96 cpm, for a target maximum sternal displacement of 5.0 cm. The model predictions also show that when the back support stiffness is less than 250 N/cm, the benefit of using a backboard is greater than for stiffer support surfaces.

CONCLUSIONS

Good quantitative agreement between the experimental data and the theoretical model suggests that the constant peak displacement CPR model provides reasonable prediction of CC mechanics during CPR over a wide range of CC rates. Conflicts in the literature are also explained by showing that backboards can significantly enhance CPR CC performance when the back support stiffness is less than 250 N/cm, while for surfaces with higher stiffness, the benefit of using a backboard is reduced.

Quality of cardiopulmonary resuscitation in out-of-hospital cardiac arrest is hampered by interruptions in chest compressions--a nationwide prospective feasibility study

AIM OF THE STUDY

Quality of cardiopulmonary resuscitation (CPR) is a critical determinant of outcome following out-of-hospital cardiac arrest. The aim of our study was to evaluate the quality of CPR provided by emergency medical service providers (Basic Life Support (BLS) capability) and emergency medical service providers assisted by paramedics, nurse anesthetists or physician-manned ambulances (Advanced Life Support (ALS) capability) in a nationwide, unselected cohort of out-of-hospital cardiac arrest cases.

METHODS

We conducted a prospective, observational study of out-of-hospital cardiac arrest with non-traumatic etiology (>18 years of age) occurring from the 1st to the 31st of January 2009 and treated by the primary Danish emergency medical service operator, covering approximately 85% of the population. One hundred and ninety-one cases were eligible for analysis. Follow-up was up to one year or death. Quality of CPR was evaluated using measurements of transthoracic impedance.

RESULTS

The majority of patients were treated by ambulances with ALS capability (54%). Interruptions in CPR related to loading of the patient into the emergency medical service vehicle were substantial, but independent of whether patients were managed by ALS or BLS capable units (222s versus 224s, P = 0.76) as were duration of interruptions during rhythm analysis alone (20s versus 22s, P = 0.33) and defibrillation (24s versus 26s, P = 0.07).

CONCLUSIONS

Nationwide, routine monitoring of transthoracic impedance is feasible. CPR is hampered by extended interruptions, particularly during loading of the patient into the emergency medical service vehicle, rhythm analysis and defibrillation.