Poor chest compression quality with mechanical compressions in simulated cardiopulmonary resuscitation: a randomized, cross-over manikin study

Introduction

Mechanical chest compression devices are being implemented as an aid in cardiopulmonary resuscitation (CPR), despite lack of evidence of improved outcome. This manikin study evaluates the CPR-performance of ambulance crews, who had a mechanical chest compression device implemented in their routine clinical practice 8 months previously. The objectives were to evaluate time to first defibrillation, no-flow time, and estimate the quality of compressions.

Methods

The performance of 21 ambulance crews (ambulance nurse and emergency medical technician) with the authorization to perform advanced life support was studied in an experimental, randomized cross-over study in a manikin setup. Each crew performed two identical CPR scenarios, with and without the aid of the mechanical compression device LUCAS. A computerized manikin was used for data sampling.

Results

There were no substantial differences in time to first defibrillation or no-flow time until first defibrillation. However, the fraction of adequate compressions in relation to total compressions was remarkably low in LUCAS-CPR (58%) compared to manual CPR (88%) (95% confidence interval for the difference: 13–50%). Only 12 out of the 21 ambulance crews (57%) applied the mandatory stabilization strap on the LUCAS device.

Conclusions

The use of a mechanical compression aid was not associated with substantial differences in time to first defibrillation or no-flow time in the early phase of CPR. However, constant but poor chest compressions due to failure in recognizing and correcting a malposition of the device may counteract a potential benefit of mechanical chest compressions.     

Effects of mechanical chest compression device with a load-distributing band on post-resuscitation injuries identified by post-mortem computed tomography

ObjectiveTo determine the effects of cardiopulmonary resuscitation (CPR) with AutoPulse™ (LDB-CPR) on post-resuscitation injuries identified by post-mortem computed tomography (PMCT). AutoPulse™ is a novel mechanical chest-compression device with a load-distributing band (LDB) that may affect post-resuscitation injury identified by PMCT.MethodsWe conducted a retrospective cohort study of non-traumatic adult out-of-hospital cardiac arrest patients whose death was confirmed in our emergency department between October 2009 and September 2014. Patients were divided according to whether LDB-CPR (LDB-CPR group) or manual CPR only (manual CPR only group) was performed. The background characteristics and post-resuscitation injuries identified by PMCT were compared between both groups. Logistic regression was used to identify risk factors for posterior rib fracture and abdominal injury.ResultsOverall, 323 patients were evaluated, with 241 (74.6%) in the LDB-CPR group. The total duration of CPR was significantly longer in the LDB-CPR group than in the manual CPR only group. Posterior rib fracture, hemoperitoneum, and retroperitoneal hemorrhage were significantly more frequent in the LDB-CPR group. The frequencies of anterior/lateral rib and sternum fracture were similar in both groups. Pneumothorax tended to be more frequent in the LDB-CPR group, although not significantly. LDB-CPR was an independent risk factor for posterior rib fracture (odds ratio 30.57, 95% confidence interval 4.15–225.49, P = 0.001) and abdominal injury (odds ratio 4.93, 95% confidence interval 1.88–12.95, P = 0.001).ConclusionsLDB-CPR was associated with higher frequencies of posterior rib fracture and abdominal injury identified by PMCT. PMCT findings should be carefully examined after LDB-CPR.     

Comparison of chest compression only and standard cardiopulmonary resuscitation for out-of-hospital cardiac arrest in Singapore

OBJECTIVE: Chest compression only cardiopulmonary resuscitation (CC-CPR) without ventilation has been proposed as an alternative to standard cardiopulmonary resuscitation (CPR) for bystanders. However, there has been controversy regarding the relative effectiveness of both of these techniques. We aim to compare the outcomes of cardiac arrest patients in the cardiac arrest and resuscitation epidemiology study who either received CC-CPR, standard CPR or no bystander CPR. METHODS: This prospective cohort study involved all out-of-hospital cardiac arrest (OHCA) patients attended to by emergency medical service (EMS) providers in a large urban centre. The data analyses were conducted secondarily on these collected data. The technique of bystander CPR was reported by paramedics who arrived at the scene. RESULTS: From 1 October 2001 to 14 October 2004, 2428 patients were enrolled into the study. Of these, 255 were EMS-witnessed arrests and were excluded. 1695 cases did not receive any bystander CPR, 287 had standard CPR and 154 CC-CPR. Patient characteristics were similar in both the standard and CC-CPR groups except for a higher incidence of residential arrests and previous heart disease sufferers in the CC-CPR group. Patients who received standard CPR (odds ratio (OR) 5.4, 95% confidence interval (CI) 2.1-14.0) or CC-CPR (OR 5.0, 95% CI 1.5-16.4) were more likely to survive to discharge than those who had no bystander CPR. There was no significant difference in survival to discharge between those who received CC-CPR and standard CPR (OR 0.9, 95% CI 0.3-3.1). CONCLUSION: We found that patients were more likely to survive with any form of bystander CPR than without. This emphasises the importance of chest compressions for OHCA patients, whether with or without ventilation.     

机械心肺复苏对心脏骤停患者复苏效果影响的Meta分析

目的:评价使用机械心肺复苏对心脏骤停患者复苏结局的影响。方法:系统检索中国知网、维普、万方、PUBMED、Web of Science等数据库中关于机械心肺复苏和徒手心肺复苏的相关文献,提取有效数据后用RevMan5.3软件进行Meta分析。结果:共计纳入20项临床研究,包含29 727例患者,其中11 104例患者在...     

The analysis of efficacy for AutoPulse™ system in flying helicopter

Aim of the study

The helicopter emergency medical service (HEMS) was introduced in Japan in 2001, and some cardiopulmonary arrest (CPA) patients are transported using this service. However, it is difficult to maintain continuous and effective manual cardiopulmonary resuscitation (CPR) in flying helicopters. To overcome this problem, the AutoPulse™ system, automated mechanical CPR devices, was induced. We conducted a retrospective study to clarify the efficacy of AutoPulse™ on CPA patients in flying helicopters.

Methods

In total, 92 CPA patients were enrolled in this study. Of these, 43 CPA patients received manual CPR (between April 2004 and June 2008), and 49 patients received AutoPulse™ CPR (between July 2008 and March 2011). We compared the manual CPR group with the AutoPulse™ group using logistic regression analysis and examined the efficacy of AutoPulse™ in flying helicopters.

Results

Rates for return of spontaneous circulation (ROSC) and survival to hospital discharge were increased in the AutoPulse™ group compared to the manual CPR group (ROSC, 30.6% [15 patients] vs. 7.0% [3 patients]; survival to hospital discharge, 6.1% [3 patients] vs. 2.3% [1 patient]). In multivariate analysis, the factors associated with ROSC were the use of AutoPulse™ (odds ratio [OR], 7.22; P = 0.005) and patients aged ≤65 years (OR, 0.31; P = 0.042).

Conclusion

The present study demonstrates that the use of AutoPulse™ in flying helicopters was significantly effective for the ROSC in CPA patients. The use of automated chest compression devices such as AutoPulse™ might be recommended at least for CPA patients transported by helicopters.     

Feasibility of automated rhythm assessment in chest compression pauses during cardiopulmonary resuscitation

Aim

To demonstrate the feasibility of doing a reliable rhythm analysis in the chest compression pauses (e.g. pauses for two ventilations) during cardiopulmonary resuscitation (CPR).

Methods

We extracted 110 shockable and 466 nonshockable segments from 235 out-of-hospital cardiac arrest episodes. Pauses in chest compressions were already annotated in the episodes. We classified pauses as ventilation or non-ventilation pause using the transthoracic impedance. A high-temporal resolution shock advice algorithm (SAA) that gives a shock/no-shock decision in 3 s was launched once for every pause longer than 3 s. The sensitivity and specificity of the SAA for the analyses during the pauses were computed.

Results

We identified 4476 pauses, 3263 were ventilation pauses and 2183 had two ventilations. The median of the mean duration per segment of all pauses and of pauses with two ventilations were 6.1 s (4.9–7.5 s) and 5.1 s (4.2–6.4 s), respectively. A total of 91.8% of the pauses and 95.3% of the pauses with two ventilations were long enough to launch the SAA. The overall sensitivity and specificity were 95.8% (90% low one-sided CI, 94.3%) and 96.8% (CI, 96.2%), respectively. There were no significant differences between the sensitivities (P = 0.84) and the specificities (P = 0.18) for the ventilation and the non-ventilation pauses.

Conclusion

Chest compression pauses are frequent and of sufficient duration to launch a high-temporal resolution SAA. During these pauses rhythm analysis was reliable. Pre-shock pauses could be minimised by analysing the rhythm during ventilation pauses when CPR is delivered at 30:2 compression:ventilation ratio.     

Rescuer fatigue during actual in-hospital cardiopulmonary resuscitation with audiovisual feedback: A prospective multicenter study

Background

Rescuer fatigue during cardiopulmonary resuscitation (CPR) is a likely contributor to variable CPR quality during clinical resuscitation efforts, yet investigations into fatigue and CPR quality degradation have only been performed in simulated environments, with widely conflicting results.

Objective

We sought to characterize CPR quality decay during actual in-hospital cardiac arrest, with regard to both chest compression (CC) rate and depth during the delivery of CCs by individual rescuers over time.

Methods

Using CPR recording technology to objectively quantify CCs and provide audiovisual feedback, we prospectively collected CPR performance data from arrest events in two hospitals. We identified continuous CPR “blocks” from individual rescuers, assessing CC rate and depth over time.

Results

135 blocks of continuous CPR were identified from 42 cardiac arrests at the two institutions. Median duration of continuous CPR blocks was 112 s (IQR 101–122). CC rate did not change significantly over single rescuer performance, with an initial mean rate of 105 ± 11/min, and a mean rate after 3 min of 106 ± 9/min (p = NS). However, CC depth decayed significantly between 90 s and 2 min, falling from a mean of 48.3 ± 9.6 mm to 46.0 ± 9.0 mm (p = 0.0006) and to 43.7 ± 7.4 mm by 3 min (p = 0.002).

Conclusions

During actual in-hospital CPR with audiovisual feedback, CC depth decay became evident after 90 s of CPR, but CC rate did not change. These data provide clinical evidence for rescuer fatigue during actual resuscitations and support current guideline recommendations to rotate rescuers during CC delivery.     

The prevalence of chest compression leaning during in-hospital cardiopulmonary resuscitation

Objective

Successful resuscitation from cardiac arrest requires the delivery of high-quality chest compressions, encompassing parameters such as adequate rate, depth, and full recoil between compressions. The lack of compression recoil (“leaning” or “incomplete recoil”) has been shown to adversely affect hemodynamics in experimental arrest models, but the prevalence of leaning during actual resuscitation is poorly understood. We hypothesized that leaning varies across resuscitation events, possibly due to rescuer and/or patient characteristics and may worsen over time from rescuer fatigue during continuous chest compressions.

Methods

This was an observational clinical cohort study at one academic medical center. Data were collected from adult in-hospital and Emergency Department arrest events using monitor/defibrillators that record chest compression characteristics and provide real-time feedback.

Results

We analyzed 112,569 chest compressions from 108 arrest episodes from 5/2007 to 2/2009. Leaning was present in 98/108 (91%) cases; 12% of all compressions exhibited leaning. Leaning varied widely across cases: 41/108 (38%) of arrest episodes exhibited <5% leaning yet 20/108 (19%) demonstrated >20% compression leaning. When evaluating blocks of continuous compressions (>120 s), only 4/33 (12%) had an increase in leaning over time and 29/33 (88%) showed a decrease (p < 0.001).

Conclusions

Chest compression leaning was common during resuscitation care and exhibited a wide distribution, with most leaning within a subset of resuscitations. Leaning decreased over time during continuous chest compression blocks, suggesting that either leaning may not be a function of rescuer fatiguing, or that it may have been mitigated by automated feedback provided during resuscitation episodes.     

Available ventilation monitoring methods during pre-hospital cardiopulmonary resuscitation

High quality cardiopulmonary resuscitation (CPR) in the pre-hospital setting has been associated with improved survival rates during cardiopulmonary arrest (CPA). Recent documentation of hyperventilation associated deterioration in hemodynamics during CPR, suggests that guided or controlled ventilation strategies may contribute to improved hemodynamics and increased survival. This article briefly reviews the mechanical methods, advantages, and disadvantages of the available ventilation monitoring methods currently available for clinical use, with an emphasis on pre-hospital implementation. We recommend that more objective measurement of ventilation during CPR be performed, with emphasis on a strategy for measuring both attempted ventilation frequency (f) and delivered tidal volume (VT). The use of improved thoracic impedance pneumography and capnography are appealing for such monitoring because of the widespread availability, but modifications to existing software and clinical data compared to a clinical standard would be required before general acceptance is possible. Other methods listed may offer advantages over these in select circumstances.     

Transthoracic impedance for the monitoring of quality of manual chest compression during cardiopulmonary resuscitation

Objective

The quality of cardiopulmonary resuscitation (CPR), especially adequate compression depth, is associated with return of spontaneous circulation (ROSC) and is therefore recommended to be measured routinely. In the current study, we investigated the relationship between changes of transthoracic impedance (TTI) measured through the defibrillation electrodes, chest compression depth and coronary perfusion pressure (CPP) in a porcine model of cardiac arrest.

Methods

In 14 male pigs weighing between 28 and 34 kg, ventricular fibrillation (VF) was electrically induced and untreated for 6 min. Animals were randomized to either optimal or suboptimal chest compression group. Optimal depth of manual compression in 7 pigs was defined as a decrease of 25% (50 mm) in anterior posterior diameter of the chest, while suboptimal compression was defined as 70% of the optimal depth (35 mm). After 2 min of chest compression, defibrillation was attempted with a 120-J rectilinear biphasic shock.

Results

There were no differences in baseline measurements between groups. All animals had ROSC after optimal compressions; this contrasted with suboptimal compressions, after which only 2 of the animals had ROSC (100% vs. 28.57%, p = 0.021). The correlation coefficient was 0.89 between TTI amplitude and compression depth (p < 0.001), 0.83 between TTI amplitude and CPP (p < 0.001).

Conclusion

Amplitude change of TTI was correlated with compression depth and CPP in this porcine model of cardiac arrest. The TTI measured from defibrillator electrodes, therefore has the potential to serve as an indicator to monitor the quality of chest compression and estimate CPP during CPR.     

Comparison of methods for the determination of cardiopulmonary resuscitation chest compression fraction

Objective

While cardiopulmonary resuscitation (CPR) chest compression fraction (CCF) is associated with out-of-hospital cardiac arrest (OHCA) outcomes, there is no standard method for the determination of CCF. We compared nine methods for calculating CCF.

Methods

We studied consecutive adult OHCA patients treated by Alabama Emergency Medical Services (EMS) agencies of the Resuscitation Outcomes Consortium (ROC) during January 1, 2010 to October 28, 2010. Paramedics used portable cardiac monitors with real-time chest compression detection technology (LifePak 12, Physio-Control, Redmond, WA). We performed both automated CCF calculation for the entire care episode as well as manual review of CPR data in 1-min epochs, defining CCF as the proportion of each treatment interval with active chest compressions. We compared the CCF values resulting from 9 calculation methods: (1) mean CCF for the entire patient care episode (automated calculation by manufacturer software), (2) mean CCF for first 3 min of patient care, (3) mean CCF for first 5 min, (4) mean CCF for first 10 min, (5) mean CCF for the entire episode except first 5 min, (6) mean CCF for last 5 min, (7) mean CCF from start to first shock, (8) mean CCF for the first half of resuscitation, and (9) mean CCF for the second half of resuscitation. We compared CCF for Methods 2–9 with Method 1 using paired t-tests with a Bonferroni-adjusted p-value of 0.006 (99.5% confidence intervals).

Results

Among 102 adult OHCA, patient demographics were: mean age 60.3 years (SD 20.8 years), African American 56.9%, male 63.7%, and shockable ECG rhythm 23.5%. Mean CPR duration was 728 s (95% CI: 647–809 s). Mean CCF for the 9 CCF calculation methods were: (1) 0.587%; (2) 0.526%; (3) 0.541%; (4) 0.566%; (5) 0.562%; (6) 0.597%; (7) 0.530%; (8) 0.550%; and (9) 0.590%. Compared with Method 1, Method 7 CCF (start to first shock) was slightly lower (−0.057; 99.5% CI: −0.100 to −0.014). There were no other statistically significant CCF differences (range: −0.054 to 0.013). Correlation between CCF 2–9 and CCF varied (ρ = 0.48–0.85).

Conclusion

CCF varies minimally with different calculation methods. Automated CCF determination may prove sufficient for evaluating CPR quality.     

Augmentation of tissue perfusion by a novel compression device increases neurologically intact survival in a porcine model of prolonged cardiac arrest

OBJECTIVE: This study was performed to determine the potential efficacy of an automated device with a load-distributing band (AutoPulse, Revivant Corporation), in improving neurologically intact survival after cardiac arrest. DESIGN: Randomized, controlled trial. SETTING: University animal laboratory. SUBJECTS: Forty-four swine (18-23 kg). INTERVENTIONS: Eight minutes after induction of untreated ventricular fibrillation, pigs were randomized to AutoPulse-CPR (A-CPR, n = 22), conventional cardiopulmonary resuscitation (CPR) with 20% anterior-posterior chest displacement (C-CPR20, n = 10) or 30% chest displacement (C-CPR30, n = 12), followed by resuscitation protocol with ventilation, defibrillation and intravenous epinephrine (adrenaline). MEASUREMENTS AND MAIN RESULTS: Aortic and right atrium blood pressure was measured with micromanometers. Regional blood flows were measured with microspheres. Coronary perfusion pressure during A-CPR was significantly higher as compared to C-CPR without epinephrine (A-CPR versus C-CPR20 versus C-CPR30; 16 +/- 1 mmHg versus 7 +/- 2 mmHg versus 11 +/- 2 mmHg, p < 0.05). A-CPR improved both myocardial flow without epinephrine (A-CPR versus C-CPR20 versus C-CPR30; 23% versus 0% versus 4%; percent of baseline, p < 0.05) and cerebral blood flow (40% versus 4% versus 19%, percent of baseline, p < 0.05). Sixteen of 22 animals receiving A-CPR regained spontaneous circulation and survived; 14/22 had normal cerebral performance (CPC 1). Four of 12 animals receiving C-CPR30 regained spontaneous circulation and survived, but only one animal had normal neurological function (14/22 versus 1/12, p < 0.0001). No animal receiving C-CPR20 achieved spontaneous circulation. At necropsy, 67% of C-CPR30 had rib fracture and 33% showed lung injury, while A-CPR and C-CPR20 resulted in no detectable injuries. CONCLUSIONS: Improved hemodynamics with AutoPulse performed CPR results in improved neurologically intact survival without subsequent thoracic or pulmonary injuries in this porcine model of prolonged cardiac arrest.     

The impact of airway management on quality of cardiopulmonary resuscitation: An observational study in patients during cardiac arrest

Background

Minimising interruptions in chest compressions is associated with improved survival from cardiac arrest. Current in-hospital guidelines recommend continuous chest compressions after the airway is secured on the premise that this will reduce no flow time. The aim of this study was to determine the effect of advanced airway use on the no flow ratio and other measures of CPR quality.

Methods

Consecutive adult patients who sustained an in-hospital cardiac arrest were enrolled in this prospective observational study. The quality of CPR was measured using the Q-CPR device (Phillips, UK) before and after an advanced airway device (endotracheal tube [ET] or laryngeal mask airway [LMA]) was inserted. Patients receiving only bag-mask ventilation were used as the control cohort. The primary outcome was no flow ratio (NFR). Secondary outcomes were chest compression rate, depth, compressions too shallow, compressions with leaning, ventilation rate, inflation time, change in impedance and time required to successfully insert airway device.

Results

One hundred patients were enrolled in the study (2008–2011). Endotracheal tube and LMA placement took similar durations (median 15.8 s (IQR 6.8–19.4) vs LMA median 8.0 s (IQR 5.5–15.9), p = 0.1). The use of an advanced airway was associated with improved no flow ratios (endotracheal tube placement (n = 50) improved NFR from baseline median 0.24 IQR 0.17–0.40) to 0.15 to (IQR 0.09–0.28), p = 0.012; LMA (n = 25) from median 0.28 (IQR 0.23–0.40) to 0.13 (IQR 0.11– 0.19), p = 0.0001). There was no change in NFR in patients managed solely with bag valve mask (BVM) (n = 25) (median 0.29 (IQR 0.18–0.59) vs median 0.26 (IQR 0.12–0.37), p = 0.888). There was no significant difference in time taken to successfully insert the airway device between the two groups.

Conclusion

The use of an advanced airway (ETT or LMA) during in-hospital cardiac arrest was associated with improved no flow ratio. Further studies are required to determine the effect of airway devices on overall patient outcomes.     

Tilting for perfusion: Head-up position during cardiopulmonary resuscitation improves brain flow in a porcine model of cardiac arrest

IntroductionCerebral perfusion is compromised during cardiopulmonary resuscitation (CPR). We hypothesized that beneficial effects of gravity on the venous circulation during CPR performed in the head-up tilt (HUT) position would improve cerebral perfusion compared with supine or head-down tilt (HDT).MethodsTwenty-two pigs were sedated, intubated, anesthetized, paralyzed and placed on a tilt table. After 6 min of untreated ventricular fibrillation (VF) CPR was performed on 14 pigs for 3 min with an automated CPR device called LUCAS (L) plus an impedance threshold device (ITD), followed by 5 min of L-CPR + ITD at 0° supine, 5 min at 30° HUT, and then 5 min at 30° HDT. Microspheres were used to measure organ blood flow in 8 pigs. L-CPR + ITD was performed on 8 additional pigs at 0°, 20°, 30°, 40°, and 50° HUT.ResultsCoronary perfusion pressure was 19 ± 2 mmHg at 0° vs. 30 ± 3 at 30° HUT (p < 0.001) and 10 ± 3 at 30° HDT (p < 0.001). Cerebral perfusion pressure was 19 ± 3 at 0° vs. 35 ± 3 at 30° HUT (p < 0.001) and 4 ± 4 at 30° HDT (p < 0.001). Brain–blood flow was 0.19 ± 0.04 ml min⁻¹ g⁻¹ at 0° vs. 0.27 ± 0.04 at 30° HUT (p = 0.01) and 0.14 ± 0.06 at 30° HDT (p = 0.16). Heart blood flow was not significantly different between interventions. With 0, 10, 20, 30, 40 and 50° HUT, ICP values were 21 ± 2, 16 ± 2, 10 ± 2, 5 ± 2, 0 ± 2, −5 ± 2 respectively, (p < 0.001), CerPP increased linearly (p = 0.001), and CPP remained constant.ConclusionDuring CPR, HDT decreased brain flow whereas HUT significantly lowered ICP and improved cerebral perfusion. Further studies are warranted to explore this new resuscitation concept.     

Outcomes of cardiopulmonary resuscitation for patients on vasopressors or inotropes: A pilot study

Hypothesis

Outcomes of critically ill patients who receive cardiopulmonary resuscitation (CPR) are poor, and the subgroup on vasopressors or inotropes before cardiopulmonary arrest (CPA) rarely survives.

Setting

The setting of the study was a critical care unit of a 350-bed community teaching hospital.

Study Design

This was a retrospective, cohort study.

Methods

A retrospective review was performed of medical records of all patients, identified through medical billing and hospital committee records, who received CPR for CPA in a critical care unit.

Results

Of 83 patients, with an average age of 66 years, 14 (17%) survived to hospital discharge. Patients with pulseless electrical activity and asystole were significantly less likely to survive (9% and none, respectively; P = .0001). Only 2 (4%) of 55 critically ill patients receiving vasopressors before CPR survived, whereas 12 of 28 patients not on vasopressors survived (P < .0001). Although mechanical ventilation just before CPR was highly associated with administration of vasopressors, ventilation was not significantly associated with mortality (P = .13). Mortality of patients on vasopressors was higher for both mechanically ventilated (95% vs 33%, P < .001) and spontaneously breathing (100% vs 64%, P = .02) patients. In multiple logistic regression analyses, administration of vasopressors was the only variable independently associated with in-hospital mortality (odds ratio, 35.1; 95% confidence interval = 4.1-304.3).

Conclusions

Survival of patients requiring CPR during critical care admission was 17%. Very few patients survived who required vasopressors or inotropes immediately before CPA. This study is limited significantly by its retrospective design and small cohort, and so this question should be reexamined in a larger study.     

The impact of a step stool on cardiopulmonary resuscitation: a cross-over mannequin study

Objective

Shallow chest compressions and incomplete recoil are common during cardiopulmonary resuscitation (CPR) and negatively affect outcomes. A step stool has the potential to alter these parameters when performing CPR in a bed but the impact has not been quantified.

Methods

We conducted a cross-over design, simulated study of in-hospital cardiac arrest. Rescuers performed a total of four 2-min segments of uninterrupted chest compressions, half of which were on a step stool. Compression characteristics were measured using a CPR-sensing defibrillator and subjective impressions were obtained from rescuer surveys. Paired analyses were performed to measure the impact of the step stool, taking into account rescuer characteristics, including height.

Results

Fifty subjects, of whom 36% were men, with a median height of 169.8 cm (range 148.6–190.5) volunteered to participate. Use of a step stool resulted in an average increase in compression depth of 4 mm (p < 0.001) and 18% increase in incomplete recoil (p < 0.001). However, unlike with incomplete recoil, the effect was more pronounced in rescuers in the lowest height tertile (9 ± 9 mm vs 2 ± 6 mm for those rescuers taller than 167 cm, p = 0.006).

Conclusions

Using a step stool when performing CPR in a bed results in a trade-off between increased compression depth and increased incomplete recoil. Given the nonlinear relationship between the increase in compression depth and rescuer height, the benefit of a step stool may outweigh the risks of incomplete release for rescuers ≤167 cm in height. The benefit is less clear in taller rescuers.     

The impact of chest compression rates on quality of chest compressions - a manikin study

Purpose

Chest compressions are often performed at a variable rate during cardiopulmonary resuscitation (CPR). The effect of compression rate on other chest compression quality variables (compression depth, duty-cycle, leaning, performance decay over time) is unknown. This randomised controlled cross-over manikin study examined the effect of different compression rates on the other chest compression quality variables.

Methods

Twenty healthcare professionals performed 2 min of continuous compressions on an instrumented manikin at rates of 80, 100, 120, 140 and 160 min⁻¹ in a random order. An electronic metronome was used to guide compression rate. Compression data were analysed by repeated measures ANOVA and are presented as mean (SD). Non-parametric data was analysed by Friedman test.

Results

At faster compression rates there were significant improvements in the number of compressions delivered (160(2) at 80 min⁻¹ vs. 312(13) compressions at 160 min⁻¹, P < 0.001); and compression duty-cycle (43(6)% at 80 min⁻¹ vs. 50(7)% at 160 min⁻¹, P < 0.001). This was at the cost of a significant reduction in compression depth (39.5(10) mm at 80 min⁻¹ vs. 34.5(11) mm at 160 min⁻¹, P < 0.001); and earlier decay in compression quality (median decay point 120 s at 80 min⁻¹ vs. 40 s at 160 min⁻¹, P < 0.001). Additionally not all participants achieved the target rate (100% at 80 min⁻¹ vs. 70% at 160 min⁻¹). Rates above 120 min⁻¹ had the greatest impact on reducing chest compression quality.

Conclusions

For Guidelines 2005 trained rescuers, a chest compression rate of 100–120 min⁻¹ for 2 min is feasible whilst maintaining adequate chest compression quality in terms of depth, duty-cycle, leaning, and decay in compression performance. Further studies are needed to assess the impact of the Guidelines 2010 recommendation for deeper and faster chest compressions.     

Manual vs. integrated automatic load-distributing band CPR with equal survival after out of hospital cardiac arrest. The randomized CIRC trial

Objective

To compare integrated automated load distributing band CPR (iA-CPR) with high-quality manual CPR (M-CPR) to determine equivalence, superiority, or inferiority in survival to hospital discharge.

Methods

Between March 5, 2009 and January 11, 2011 a randomized, unblinded, controlled group sequential trial of adult out-of-hospital cardiac arrests of presumed cardiac origin was conducted at three US and two European sites. After EMS providers initiated manual compressions patients were randomized to receive either iA-CPR or M-CPR. Patient follow-up was until all patients were discharged alive or died. The primary outcome, survival to hospital discharge, was analyzed adjusting for covariates, (age, witnessed arrest, initial cardiac rhythm, enrollment site) and interim analyses. CPR quality and protocol adherence were monitored (CPR fraction) electronically throughout the trial.

Results

Of 4753 randomized patients, 522 (11.0%) met post enrollment exclusion criteria. Therefore, 2099 (49.6%) received iA-CPR and 2132 (50.4%) M-CPR. Sustained ROSC (emergency department admittance), 24 h survival and hospital discharge (unknown for 12 cases) for iA-CPR compared to M-CPR were 600 (28.6%) vs. 689 (32.3%), 456 (21.8%) vs. 532 (25.0%), 196 (9.4%) vs. 233 (11.0%) patients, respectively. The adjusted odds ratio of survival to hospital discharge for iA-CPR compared to M-CPR, was 1.06 (95% CI 0.83–1.37), meeting the criteria for equivalence. The 20 min CPR fraction was 80.4% for iA-CPR and 80.2% for M-CPR.

Conclusion

Compared to high-quality M-CPR, iA-CPR resulted in statistically equivalent survival to hospital discharge.     

Hemodynamic improvement of a LUCAS 2 automated device by addition of an impedance threshold device in a pig model of cardiac arrest

Introduction

The combination of the LUCAS 2 (L-CPR) automated CPR device and an impedance threshold device (ITD) has been widely implemented in the clinical field. This animal study tested the hypothesis that the addition of an ITD on L-CPR would enhance cerebral and coronary perfusion pressures.

Methods

Ten female pigs (39.0 ± 2.0 kg) were sedated, intubated, anesthetized with isofluorane, and paralyzed with succinylcholine (93.3 μg/kg/min) to inhibit the potential confounding effect of gasping. After 4 min of untreated ventricular fibrillation, 4 min of L-CPR + an active ITD or L-CPR + a sham ITD was initiated and followed by another 4 min of the alternative method of CPR. Systolic blood pressure (SBP), diastolic blood pressure (DBP), diastolic right atrial pressure (RAP), intracranial pressure (ICP), airway pressure, and end tidal CO₂ (ETCO₂) were recorded continuously. Data expressed as mean mmHg ± SD.

Results

Decompression phase airway pressure was significantly lower with L-CPR + active ITD versus L-CPR + sham ITD (−5.3 ± 2.2 vs. −0.5 ± 0.6; p < 0.001). L-CPR + active ITD treatment resulted in significantly improved hemodynamics versus L-CPR + sham ITD: ETCO₂, 35 ± 6 vs. 29 ± 7 (p = 0.015); SBP, 99 ± 9 vs. 93 ± 15 (p = 0.050); DBP, 24 ± 12 vs. 19 ± 15 (p = 0.006); coronary perfusion pressure, 29 ± 8 vs. 26 ± 7 (p = 0.004) and cerebral perfusion pressure, 24 ± 13 vs. 21 ± 12 (p = 0.028).

Conclusions

In pigs undergoing L-CPR the addition of the active ITD significantly reduced intrathoracic pressure and increased vital organ perfusion pressures.     

A manually powered mechanical resuscitation device used by a single rescuer: a randomised controlled manikin study

Purpose

The goal of this randomized, open, controlled crossover manikin study was to compare the performance of “Animax”, a manually operated hand-powered mechanical resuscitation device (MRD) to standard single rescuer basic life support (BLS).

Methods

Following training, 80 medical students performed either standard BLS or used an MRD for 12 min in random order. We compared the quality of chest compressions (effective compressions, compression depth and rate, absolute hands-off time, hand position, decompression), and of ventilation including the number of gastric inflations. An effective compression was defined as a compression performed with correct depth, hand position and decompression.

Results

The use of the MRD resulted in a significantly higher number of effective compressions compared to standard BLS (67 ± 34 vs. 41 ± 34%, p < 0.001). In a comparison with standard BLS, the use of the MRD resulted in less absolute hands-off time (264 ± 57 vs. 79 ± 40 s, p < 0.001) and in a higher minute-volume (1.86 ± 0.7 vs. 1.62 ± 0.7 l, p = 0.020). However, ventilation volumes were below the 2005 ERC guidelines for both methods. Gastric inflations occurred only in 0 ± 0.1% with the MRD compared to 3 ± 7% during standard BLS (p < 0.001).

Conclusion

Single rescuer cardio-pulmonary resuscitation with the manually operated MRD was superior to standard BLS regarding chest compressions in this simulation study. The MRD delivered a higher minute-volume but did not achieve the recommended minimal volume. Further clinical studies are needed to test the MRD's safety and efficacy in patients.