Increased cortical cerebral blood flow with LUCAS; a new device for mechanical chest compressions compared to standard external compressions during experimental cardiopulmonary resuscitation

Manual versus mechanical cardiopulmonary resuscitation. An experimental study in pigs

BACKGROUND

Optimal manual closed chest compressions are difficult to give. A mechanical compression/decompression device, named LUCAS, is programmed to give compression according to the latest international guidelines (2005) for cardiopulmonary resuscitation (CPR). The aim of the present study was to compare manual CPR with LUCAS-CPR.

METHODS

30 kg pigs were anesthetized and intubated. After a base-line period and five minutes of ventricular fibrillation, manual CPR (n = 8) or LUCAS-CPR (n = 8) was started and run for 20 minutes. Professional paramedics gave manual chest compression's alternating in 2-minute periods. Ventilation, one breath for each 10 compressions, was given to all animals. Defibrillation and, if needed, adrenaline were given to obtain a return of spontaneous circulation (ROSC).

RESULTS

The mean coronary perfusion pressure was significantly (p < 0.01) higher in the mechanical group, around 20 mmHg, compared to around 5 mmHg in the manual group. In the manual group 54 rib fractures occurred compared to 33 in the LUCAS group (p < 0.01). In the manual group one severe liver injury and one pressure pneumothorax were also seen. All 8 pigs in the mechanical group achieved ROSC, as compared with 3 pigs in the manual group.

CONCLUSIONS

LUCAS-CPR gave significantly higher coronary perfusion pressure and significantly fewer rib fractures than manual CPR in this porcine model.

Part 10: Pediatric basic and advanced life support: 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations

Note From the Writing Group: Throughout this article, the reader will notice combinations of superscripted letters and numbers (eg, “Family Presence During ResuscitationPeds-003”). These callouts are hyperlinked to evidence-based worksheets, which were used in the development of this article. An appendix of worksheets, applicable to this article, is located at the end of the text. The worksheets are available in PDF format and are open access.

Transthoracic application of electrical cardiopulmonary resuscitation for treatment of cardiac arrest

OBJECTIVE

Observational studies have shown that muscular stimulation contracting the thoracic cage may produce coronary perfusion pressures equal to manual chest compressions. This study examined electrical cardiopulmonary resuscitation for coronary perfusion pressures during ventricular fibrillation in a porcine model of cardiac arrest.

DESIGN

Prospective randomized controlled study.

SETTING

University affiliated research institute.

SUBJECTS

Domestic male pigs.

INTERVENTIONS

In seven domestic male pigs (40 +/- 2 kg), ventricular fibrillation was induced electrically and untreated for 10 secs. For each ventricular fibrillation episode, one of 16 electrical cardiopulmonary resuscitation stimulation protocols (pulse trains) or manual chest compression was applied. Each compression protocol was applied for 20 secs, followed by a defibrillation shock. The experimental procedure was performed across one or more randomized complete blocks. The electrical cardiopulmonary resuscitation pulse trains were defined by four two-level factors: pulse width (0.15 and 7.5 msec), pulse period (15 and 30 msec), train width (50 and 200 msec), and train rate (60 or 120 compressions per min). Pulse trains comprised two groups, based on pulse width (skeletal-based, 0.15 msec; cardiac-based, 7.5 msec).

MEASUREMENTS AND MAIN RESULTS

Train width was the significant design parameter for producing efficacious levels of coronary perfusion pressures for the skeletal-based electrical cardiopulmonary resuscitation pulse trains (p = 0.02). Both train width and train rate were significant design parameters for producing efficacious levels of coronary perfusion pressures for the cardiac-based electrical cardiopulmonary resuscitation pulse trains (p < 0.001, p = 0.5, respectively). Optimal skeletal-based and cardiac-based electrical cardiopulmonary resuscitation pulse trains were significantly better than ventricular fibrillation (p = 0.01, p = 0.01, respectively) and equivalent to manual chest compression (p = 0.2, p = 0.7, respectively) for sufficient coronary perfusion pressure levels.

CONCLUSIONS

Optimal skeletal-based and cardiac-based electrical cardiopulmonary resuscitation pulse train parameters generated levels of coronary perfusion pressure significantly greater than ventricular fibrillation and comparable with manual chest compression over a short interval of untreated cardiac arrest.

Feasibility of intra-arrest hypothermia induction: A novel nasopharyngeal approach achieves preferential brain cooling

AIM

In patients with cardiopulmonary arrest, brain cooling may improve neurological outcome, especially if applied prior to or during early reperfusion. Thus it is important to develop feasible cooling methods for pre-hospital use. This study examines cerebral and compartmental thermokinetic properties of nasopharyngeal cooling during various blood flow states.

METHODS

Ten swine (40+/-4kg) were anesthetized, intubated and monitored. Temperature was determined in the frontal lobe of the brain, in the aorta, and in the rectum. After the preparatory phase the cooling device (RhinoChill system), which produces evaporative cooling in the nasopharyngeal area, was activated for 60min. The thermokinetic response was evaluated during stable anaesthesia (NF, n=3); during untreated cardiopulmonary arrest (ZF, n=3); during CPR (LF, n=4).

RESULTS

Effective brain cooling was achieved in all groups with a median cerebral temperature decrease of -4.7 degrees C for NF, -4.3 degrees C for ZF and -3.4 degrees C for LF after 60min. The initial brain cooling rate however was fastest in NF, followed by LF, and was slowest in ZF; the median brain temperature decrease from baseline after 15min of cooling was -2.48 degrees C for NF, -0.12 degrees C for ZF, and -0.93 degrees C for LF, respectively. A median aortic temperature change of -2.76 degrees C for NF, -0.97 for LF and +1.1 degrees C for ZF after 60min indicated preferential brain cooling in all groups.

CONCLUSION

While nasopharyngeal cooling in swine is effective at producing preferential cerebral hypothermia in various blood flow states, initial brain cooling is most efficient with normal circulation.

The optimal phasic relationship between synchronized shock and mechanical chest compressions

OBJECTIVE

Pauses for shock delivery in chest compressions are detrimental to the success of resuscitation and may be eliminated with the use of mechanical chest compressors. However, the optimal phasic relationship between mechanical chest compression and defibrillation is still unknown. We therefore undertook a study to assess the effects of timing of defibrillation in the mechanical chest compression cycle on the defibrillation threshold (DFT) using a porcine model of cardiac arrest.

METHODS

Ventricular fibrillation was electrically induced and untreated for 10s in 8 domestic pigs weighing between 26 and 30 kg. Mechanical chest compression was then continuously performed for 25s, followed by a biphasic electrical shock which was delivered to the animal at 6 randomized coupling phases, including a control phase, with a pre-determined energy setting. The control phase was chosen at a constant 2s following discontinued chest compression. A novel grouped up-and-down DFT testing protocol was used to compare the success rate at different coupling phases. After a recovery interval of 4 min, the testing sequence was repeated, resulting in a total of 60 test shocks delivered to each animal.

RESULTS

No difference between the delivered shock energy, voltage and current were observed among the 6 study phases. The defibrillation success rate, however, was significantly higher when shocks were delivered in the upstroke phase of mechanical chest compression.

CONCLUSION

Defibrillation efficacy is maximal when electrical shock is delivered in the upstroke phase of mechanical chest compression.

Monitoring in resuscitation: comparison of cardiac output measurement between pulmonary artery catheter and NICO

AIM

The cardiac output and coronary perfusion pressure generated from chest compressions during resuscitation manoeuvres can predict effectiveness and successful outcome. Until now, there is no good method for haemodynamic monitoring during resuscitation. Noninvasive partial carbon dioxide rebreathing system (NICO, Novametrix Medical Systems, Inc., Wallingford, CT, USA) is a relatively new non-invasive alternative to thermodilution for measuring cardiac output. The accuracy of the NICO system has not been evaluated during resuscitation. The aim of this study is to compare thermodilution cardiac output method with NICO system and to assess the utility of NICO during resuscitation.

METHODS AND DESIGN

Experimental study in 24 Yorkshire pigs. Paired measurements of cardiac output were determined during resuscitation (before ventricular fibrillation and after 5, 15, 30 and 45 min of resuscitation) in the supine position. The average of 3 consecutive thermodilution cardiac output measurements (10 ml 20 degrees C saline) was compared with the corresponding NICO measurement.

RESULTS

Bland and Altman plot and Lin's concordance coefficient showed a high correlation between NICO and thermodilution cardiac output measurements although NICO has a tendency to underestimate cardiac output when compared to thermodilution at normal values of cardiac output.

CONCLUSIONS

There is a high degree of agreement between cardiac output measurements obtained with NICO and thermodilution cardiac output during resuscitation. The present study suggests that the NICO system may be useful to measure cardiac output generated during cardiopulmonary resuscitation.

No difference in autopsy detected injuries in cardiac arrest patients treated with manual chest compressions compared with mechanical compressions with the LUCAS device--a pilot study

AIM

To compare the variety and incidence of internal injuries after manual and mechanical chest compressions during CPR.

METHODS

In a prospective pilot study conducted in two Swedish cities, 85 patients underwent autopsy after unsuccessful resuscitation attempts with manual or mechanical chest compressions, the latter with the LUCAS device. Autopsy was performed and the results were evaluated according to a specified protocol.

RESULTS

No injuries were found in 26/47 patients in the manual group and in 16/38 patients in the LUCAS group (p=0.28). Sternal fracture was present in 10/47 in the manual group and 11/38 in the LUCAS group (p=0.46), and there were multiple rib fractures (> or =3 fractures) in 13/47 in the manual group and in 17/38 in the LUCAS group (p=0.12). Bleeding in the ventral mediastinum was noted in 2/47 and 3/38 in the manual and LUCAS groups respectively (p=0.65), retrosternal bleeding in 1/47 and 3/38 (p=0.32), epicardial bleeding in 1/47 and 4/38 (p=0.17), and haemopericardium in 4/47 and 3/38 (p=1.0) respectively. One patient in the LUCAS group had a small rift in the liver and one patient in the manual group had a rift in the spleen. These injuries were not considered to have contributed to the patient's death.

CONCLUSION

Mechanical chest compressions with the LUCAS device appear to be associated with the same variety and incidence of injuries as manual chest compressions.

Improved chest recoil using an adhesive glove device for active compression-decompression CPR in a pediatric manikin model

OBJECTIVE

We developed an adhesive glove device (AGD) to perform ACD-CPR in pediatric manikins, hypothesizing that AGD-ACD-CPR provides better chest decompression compared to standard (S)-CPR.

DESIGN

Split-plot design randomizing 16 subjects to test four manikin-technique models in a crossover fashion to AGD-ACD-CPR vs. S-CPR. Healthcare providers performed 5min of CPR with 30:2 compression:ventilation ratio in the four manikin models: (1) adolescent; (2) child two-hand; (3) child one-hand; and (4) infant two-thumb.

METHODS

Modified manikins recorded compression pressure (CP), compression depth (CD) and decompression depth (DD). The AGD consisted of a modified oven mitt with an adjustable strap; a Velcro patch was sewn to the palmer aspect. The counter Velcro patch was bonded to the anterior chest wall. For infant CPR, the thumbs of two oven mitts were stitched together with Velcro. Subjects were asked to actively pull up during decompression. Subjects' heart rate (HR), respiratory rate (RR) and recovery time (RT) for HR/RR to return to baseline were recorded. Subjects were blinded to data recordings. Data (mean+/-SEM) were analyzed using a two-tailed paired t-test. Significance was defined qualitatively as P< or =0.05.

RESULTS

Mean decompression depth difference was significantly greater with AGD-ACD-CPR compared to S-CPR; 38-75% of subjects achieved chest decompression to or beyond baseline. AGD-ACD-CPR provided 6-12% fewer chest compressions/minute than S-CPR group. There was no significant difference in CD, CP, HR, RR and RT within each group comparing both techniques.

CONCLUSION

A simple, inexpensive glove device for ACD-CPR improved chest decompression with emphasis on active pull in manikins without excessive rescuer fatigue. The clinical implication of fewer compressions/minute in the AGD group needs to be evaluated.

Cardiopulmonary resuscitation: from the beginning to the present day

Cardiac arrest represents a dramatic event that can occur suddenly and often without premonitory signs, characterized by sudden loss of consciousness and breathing after cardiac output ceases and both coronary and cerebral blood flows stop. Restarting of the blood flow by cardiopulmonary resuscitation potentially re-establishes some cardiac output and organ blood flows. This article summarizes the major events that encompass the history of cardiopulmonary resuscitation, beginning with ancient history and evolving into the current American Heart Association's commitment to save hearts.

Percutaneous left ventricular assist in ischemic cardiac arrest

BACKGROUND

Ischemic cardiac arrest represents a challenge for optimal emergency revascularization therapy. A percutaneous left ventricular assist device (LVAD) may be beneficial.

OBJECTIVE

To determine the effect of a percutaneous LVAD during cardiac arrest without chest compressions and to assess the effect of fluid loading.

DESIGN

Totally, 16 pigs randomized to either conventional or intensive fluid with LVAD support during ventricular fibrillation (VF).

SETTING

Acute experimental trial with pigs under general anesthesia.

SUBJECTS

Farm pigs of both sexes.

INTERVENTIONS

After randomization for fluid infusion, VF was induced by balloon occlusion of the proximal left anterior descending artery. LVAD and fluid were started after VF had been induced.

MEASUREMENTS

Brain, kidney, myocardial tissue perfusion, and cardiac index were measured with the microsphere injection technique at baseline, 3, and 15 minutes. Additional hemodynamic monitoring continued until 30 minutes.

MAIN RESULTS

At 15 minutes, vital organ perfusion was maintained without significant differences between the two groups. Mean cardiac index at 3 minutes of VF was 1.2 L x min(-1) x m2 (29% of baseline, p < 0.05). Mean perfusion at 3 minutes was 65% in the brain and 74% in the myocardium compared with baseline (p < 0.05), then remained unchanged during the initial 15 minutes. At 30 minutes, LVAD function was sustained in 11 of 16 animals (8 of 8 intensified fluid vs. 3 of 8 conventional fluid) and was associated with intensified fluid loading (p < 0.001).

CONCLUSIONS

During VF, a percutaneous LVAD may sustain vital organ perfusion. A potential clinical role of the device during cardiac arrest has yet to be established.

Evolution and new perspective of chest compression mechanical devices

Cardiac arrest is a major concern in health care, owing to its high incidence and mortality rates. Since the development of external cardiopulmonary resuscitation (CPR), there has been little advancement in nonpharmacologic therapies that have increased survival rates associated with cardiac arrest. Consequently, there has been much interest in the development of new techniques to improve the efficacy of CPR, particularly in the development of devices. Initially, many of the devices developed were not considered functional and failed to gain acceptance in the clinical setting. Recently, however, several devices have been developed which have progressed the administration of CPR and garnered acceptance in the clinical setting. In this article we will briefly review some of the more common mechanical devices developed to increase the safety and efficacy of CPR administration.

Miniaturization of a Chest Compressor for Cardiopulmonary Resuscitation

A miniaturized chest compressor (MCC®) for cardiopulmonary resuscitation (CPR) was designed to serve as a compact portable device to overcome limitations of manual chest compression and of currently marketed mechanical devices. We sought to especially address constraints of size and weight of current devices, together with the need for ease of application and consistent compressions with appropriate force and depth. We further intended that the device allows for ease of evacuation and transport through small spaces. These objectives are responsive to the increasingly recognized requirements for uninterrupted chest compression including that which results from operator fatigue during manual compressions. Utilizing a garment applied to the torso, the device incorporated a telescopic piston for chest compression. The compressor was pneumatically powered so as to avoid the added weight and potential electrical adversity of power delivered by batteries. Pneumatic power was supplied by the same compressed air or oxygen tank, which is routinely carried by professional emergency medical rescuers. The MCC® was tested on a porcine model during cardiac arrest and resuscitation with comparisons to the current industry standard, the Michigan Thumper®. Arterial, carotid, and coronary perfusion pressures, together with end-tidal carbon dioxide as a surrogate for cardiac output, were measured. The MCC® threshold levels of pressure, flow, and end-tidal PCO2 are achieved, which were predictive of successful defibrillation with restoration of spontaneous circulation. We conclude that the MCC® is as effective as that of the established industry standard, the Michigan Thumper®, with the potential advantage of portability and facile application, especially for out-of-hospital resuscitation.

Mechanical devices for cardiopulmonary resuscitation

PURPOSE OF REVIEW

The most current practice guidelines for cardiopulmonary resuscitation published by the American Heart Association and European Resuscitation Council have placed the highest priority on achieving the most optimal circulation possible following sudden cardiac arrest through the delivery of early, consistent, high-quality and infrequently interrupted chest compressions during resuscitative efforts. The purpose of this review is to analyze the most recent trials involving adjunct mechanical devices designed to optimize blood flow to vital organs during cardiopulmonary resuscitation conditions.

RECENT FINDINGS

Six devices show substantial promise based on the compelling results of numerous animal and small-scale clinical trials. All of these promising interventions, however, have yet to be validated in definitive clinical trials, particularly those examining long-term survival and neurological function.

SUMMARY

Markedly enhanced circulation during cardiopulmonary resuscitation efforts has been found to be a critical element for effecting successful resuscitation. Preliminary studies of adjunct mechanical cardiopulmonary resuscitation devices have revealed significant increases in improved hemodynamics in both animal models and human studies, as well as improvements in short-term human survival in the clinical setting. Several of these devices are currently undergoing definitive clinical trials that hopefully will establish irrefutable efficacy and improved long-term neurological outcomes.

Characteristics and outcome among patients suffering from out-of-hospital cardiac arrest with the emphasis on availability for intervention trials

AIM

To describe all patients treated for out-of-hospital cardiac arrest (OHCA) according to the Utstein criteria and their characteristics and outcome with emphasis on whether they were available for early intervention trials.

DESIGN

Retrospective analysis of a study where data were collected prospectively.

SETTING

The Municipality of Göteborg/Mölndal in Sweden.

PATIENTS

All patients suffering from out-of-hospital cardiac arrest in the Municipality of Göteborg/Mölndal in whom cardiopulmonary resuscitation (CPR) was attempted between May 2003 and May 2005.

INTERVENTIONS

Part of the study cohort, i.e. patients with a witnessed, non-traumatic, out-of-hospital cardiac arrest were distributed (cluster) to mechanical (LUCAS) or manual chest compression.

RESULTS

The overall survival to discharge from hospital among the 508 patients was 8.5%. The corresponding value for non-cardiac cases was 5.1% and for cardiac cases if crew witnessed 16.1%, bystander witnessed 12.7% and non-witnessed 1.4%. Fifty-nine percent of the patients fulfilled the inclusion criteria for the trial and had no exclusion criteria and 9.7% of these survived to discharge. Ten percent of patients fulfilled the inclusion criteria but were excluded and 20.4% survived to discharge. Thirty-one percent of patients did not fulfil the inclusion criteria and 2.5% survived. Among patients included in the LUCAS group, many of the survivors, 10/13 (77%), experienced a rapid return of spontaneous circulation (ROSC) before the application of the device.

CONCLUSION

Among patients with OHCA in whom CPR was started 8.5% survived to hospital discharge and 59% were theoretically available for an early intervention trial. These patients have a different outcome compared with patients not available. However, among those available, the majority of survivors had a rapid ROSC before the application of the intervention (LUCAS). This raises concerns about the potential for early intervention trials to improve outcome after OHCA.

Cardiac arrest with continuous mechanical chest compression during percutaneous coronary intervention

Mechanical chest compression may be necessary to make coronary intervention possible during resuscitation. We report our experience using the Lund University Cardiac Arrest System (LUCAS, Jolife, Lund, Sweden) which is a gas-driven sternal compression device that incorporates a suction cup for active decompression. During the last 13 months LUCAS has been used in our catheterisation laboratory to maintain adequate organ perfusion pressure in 13 patients with cardiac arrest or severe hypotension and bradycardia (male/female ratio 1.6, mean age 59+/-19). The mean compression time was 105+/-60min (range 45-240), and the mean systolic and diastolic blood pressure obtained was 81+/-23 and 34+/-21mmHg, respectively. Angiography and eventually percutanous coronary intervention was possible in all cases during ongoing automatic chest compression. Three patients survived the procedure, but no patients were discharged alive. In two cases we found inadequate flow in the anterior descending artery, and in one case the invasive measurements revealed inadequate coronary perfusion pressure. There were no excessive intra-thoracic or intra-abdominal injuries. We conclude that the LUCAS device is suitable during cardiac catheterisation and intervention, and the device ensures an adequate systemic blood pressure in most patients without life-threatening injuries.

Miniaturized mechanical chest compressor: a new option for cardiopulmonary resuscitation

AIM OF STUDY

After cardiac arrest, uninterrupted chest compressions with restoration of myocardial blood flow facilitates restoration of spontaneous circulation. We recognized that this may best be accomplished with a mechanical device and especially so during transport. We therefore sought to develop a lightweight, portable chest compressor which may be carried on the belt or attached to the oxygen tank typically carried on the back of the first response rescuer. A miniaturized pneumatic chest compressor (MCC) weighing less than 2 kg was developed and compared with a currently marketed "Michigan Thumper", which weighed 19 kg. We hypothesized that the 2 kg, low profile, portable device will be as effective as the standard pneumatic Thumper for restoring circulation during CPR.

MATERIAL AND METHODS

Ventricular fibrillation was electrically induced in 10 domestic male pigs weighing 39+/-2 kg, and untreated for 5 min. Animals were then randomized to receive chest compressions with either the MCC or the Thumper. After 5 min of mechanical chest compression, defibrillation was attempted with a 150 J biphasic shock. Coronary perfusion pressure (CPP) and end tidal PCO(2) (EtPCO(2)) were measured by conventional techniques together with right carotid artery blood flow (CBF).

RESULTS

Four of five animals compressed with the Thumper and each animal compressed with the MCC were successfully resuscitated. No significant differences in CPP, EtPCO(2), CBF and post-resuscitation myocardial function were observed between groups. Resuscitated animals survived for more than 72 h without neurological impairment.

CONCLUSION

The low profile, 2 kg miniaturized chest compressor is as effective as the conventional Thumper in an experimental model of CPR.

Do we hyperventilate cardiac arrest patients?

INTRODUCTION

Hyperventilation during cardiopulmonary resuscitation is detrimental to survival. Several clinical studies of ventilation during hospital and out-of-hospital cardiac arrest have demonstrated respiratory rates far in excess of the 10 min(-1) recommended by the ERC. We observed detailed ventilation variables prospectively during manual ventilation of 12 cardiac arrest patients treated in the emergency department of a UK Hospital.

METHODS

Adult cardiac arrest patients were treated according to ERC guidelines. Ventilation was provided using a self-inflating bag. A COSMOplus monitor (Respironics Inc.) was inserted into the ventilation circuit at the beginning of the resuscitation from which ventilation data were downloaded to a laptop.

RESULTS

Data were collected from 12 patients (7 male; age 47-82 years). The maximum respiratory rate was 9-41 breaths per minute (median 26). The median tidal volume was 619 ml (374-923 ml) and the median respiratory rate was 21 min(-1) (7-37 min(-1)). The corresponding median minute volume was 13.0 l/min (4.6-21.3 min(-1)). Median peak inspiratory pressures were 60.6 cmH(2)O (range 46-106). Airway pressure was positive for 95.3% of the respiratory cycle (range 87.9-100%).

CONCLUSIONS

Hyperventilation was common, mostly through high respiratory rates rather than excessive tidal volumes. This is the first study to document tidal volumes and airway pressures during resuscitation. The persistently high airway pressures are likely to have a detrimental effect on blood flow during CPR. Guidelines on respiratory rates are well known, but it would appear that in practice they are not being observed.

Haemodynamic effects of adrenaline (epinephrine) depend on chest compression quality during cardiopulmonary resuscitation in pigs

BACKGROUND

Adrenaline (epinephrine) is used during cardiopulmonary resuscitation (CPR) based on animal experiments without supportive clinical data. Clinically CPR was reported recently to have much poorer quality than expected from international guidelines and what is generally done in laboratory experiments. We have studied the haemodynamic effects of adrenaline during CPR with good laboratory quality and with quality simulating clinical findings and the feasibility of monitoring these effects through VF waveform analysis.

METHODS AND RESULTS

After 4 min of cardiac arrest, followed by 4 min of basic life support, 14 pigs were randomised to ClinicalCPR (intermittent manual chest compressions, compression-to-ventilation ratio 15:2, compression depth 30-38 mm) or LabCPR (continuous mechanical chest compressions, 12 ventilations/min, compression depth 45 mm). Adrenaline 0.02 mg/kg was administered 30 s thereafter. Plasma adrenaline concentration peaked earlier with LabCPR than with ClinicalCPR, median (range), 90 (30, 150) versus 150 (90, 270) s (p = 0.007), respectively. Coronary perfusion pressure (CPP) and cortical cerebral blood flow (CCBF) increased and femoral blood flow (FBF) decreased after adrenaline during LabCPR (mean differences (95% CI) CPP 17 (6, 29) mmHg (p = 0.01), FBF -5.0 (-8.8, -1.2) ml min(-1) (p = 0.02) and median difference CCBF 12% of baseline (p = 0.04)). There were no significant effects during ClinicalCPR (mean differences (95% CI) CPP 4.7 (-3.2, 13) mmHg (p = 0.2), FBF -0.2 (-4.6, 4.2) ml min(-1)(p = 0.9) and CCBF 3.6 (-1.8, 9.0)% of baseline (p = 0.15)). Slope VF waveform analysis reflected changes in CPP.

CONCLUSION

Adrenaline improved haemodynamics during laboratory quality CPR in pigs, but not with quality simulating clinically reported CPR performance.

Effects of compression depth and pre-shock pauses predict defibrillation failure during cardiac arrest

BACKGROUND

Cardiopulmonary resuscitation (CPR) and electrical defibrillation are the primary treatment options for ventricular fibrillation (VF). While recent studies have shown that providing CPR prior to defibrillation may improve outcomes, the effects of CPR quality remain unclear. Specifically, the clinical effects of compression depth and pauses in chest compression prior to defibrillation (pre-shock pauses) are unknown.

METHODS

A prospective, multi-center, observational study of adult in-hospital and out-of-hospital cardiac resuscitations was conducted between March 2002 and December 2005. An investigational monitor/defibrillator equipped to measure compression characteristics during CPR was used.

RESULTS

Data were analyzed from 60 consecutive resuscitations in which a first shock was administered for VF. The primary outcome was first shock success defined as removal of VF for at least 5s following defibrillation. A logistic regression analysis demonstrated that successful defibrillation was associated with shorter pre-shock pauses (adjusted odds ratio 1.86 for every 5s decrease; 95% confidence interval 1.10-3.15) and higher mean compression depth during the 30s of CPR preceding the pre-shock pause (adjusted odds ratio 1.99 for every 5mm increase; 95% confidence interval 1.08-3.66).

CONCLUSIONS

The quality of CPR prior to defibrillation directly affects clinical outcomes. Specifically, longer pre-shock pauses and shallow chest compressions are associated with defibrillation failure. Strategies to correct these deficiencies should be developed and consideration should be made to replacing current-generation automated external defibrillators that require long pre-shock pauses for rhythm analysis.

Clinical consequences of the introduction of mechanical chest compression in the EMS system for treatment of out-of-hospital cardiac arrest—A pilot study

AIM

To evaluate the outcome among patients suffering from out-of-hospital cardiac arrest (OHCA) after the introduction of mechanical chest compression (MCC) compared with standard cardiopulmonary resuscitation (SCPR) in two emergency medical service (EMS) systems.

METHODS

The inclusion criterion was witnessed OHCA. The exclusion criteria were age < 18 years, the following judged etiologies behind OHCA: trauma, pregnancy, hypothermia, intoxication, hanging and drowning or return of spontaneous circulation (ROSC) prior to the arrival of the advanced life support (ALS) unit. Two MCC devices were allocated during six-month periods between four ALS units for a period of two years (cluster randomisation).

RESULTS

In all, 328 patients fulfilled the criteria for participation and 159 were allocated to the MCC tier (the device was used in 66% of cases) and 169 to the SCPR tier. In the MCC tier, 51% had ROSC (primary end-point) versus 51% in the SCPR tier. The corresponding values for hospital admission alive (secondary end-point) were 38% and 37% (NS). In the subset of patients in whom the device was used, the percentage who had ROSC was 49% versus 50% in a control group matched for age, initial rhythm, aetiology, bystander-/crew-witnessed status and delay to CPR. The percentage of patients discharged alive from hospital after OHCA was 8% versus 10% (NS) for all patients and 2% versus 4%, respectively (NS) for the patients in the subset (where the device was used and the matched control population).

CONCLUSION

In this pilot study, the results did not support the hypothesis that the introduction of mechanical chest compression in OHCA improves outcome. However, there is room for further improvement in the use of the device. The hypothesis that this will improve outcome needs to be tested in further prospective trials.