Active Compression-decompression Research Articles

The Optimization Study on Time Sequence of Enhanced External Counter-Pulsation in AEI-CPR

To improve the aortic pressure and myocardial perfusion pressure during cardiac arrest, this study is designed to optimize sequence of Enhanced External Counter- Pulsation (EECP) for a cardiopulmonary resuscitation (CPR) technique — Active Compression-Decompression CPR coupled with EECP and Inspiratory Impedance Threshold Valve (AEI-CPR). EECP is lower-limbs compression equipment for AEI-CPR that enhanced blood regurgitation during chest decompression. Different occasion for EECP performance would bring different hemodynamic effect. A mathematical model of human circulatory system used to research AEI-CPR has been established. And then the AEI-CPR hemodynamic effect to the blood circulatory system is performed on the model. A genetic algorithm (GA) that used to find optimum sequence of the EECP is performed on the model when other parameters of external force for AEI-CPR are definite. At first, set the maximum strength of chest compression, chest decompression and lower-limbs compression at 400Nt, 160Nt and 300mmHg, respectively. Set the frequency of CPR at 100min-1 and the ratio of chest compression compared to LLCP at 1:1. Then, after genetic algorithm is performed on the established model, fifty groups of optimal results are obtained. The maximum coronary perfusion pressure (CPP) takes place when the EECP begin its compression at 0.2s and the interval among crural, femoral and iliac compression is 0.05s. By applying the optimization algorithm on the CPR mathematical model, the optimum sequence of the EECP could be found. And the experiment results indicate that obvious hemodynamic effect is attained when the EECP began compression at the end of chest compression.

Abstract P22: An Impedance Threshold Device Combined with an Automated Active Compression Decompression CPR Device (LUCAS) Improves the Chances For Survival in Pigs in Cardiac Arrest

Background: By lowering intrathoracic pressure during the chest recoil phase of CPR, the impedance threshold device (ITD) increases circulation and the rate of return of spontaneous circulation (ROSC). This study evaluated the ITD combined with a new automated CPR device, the US version of the LUCAS, that compresses the chest and then pulls upwards with a 3 lb force. Methods and Results: After 6 min of untreated ventricular fibrillation, anesthetized female pigs (40.0±0.7 kg) were randomized to 6 min of CPR (100 compressions/min with LUCAS and ventilation: 1.0 FiO2, tidal volume of 10ml/kg, rate 12/min) with an active (−10 cm H2O resistance) (n=12) or sham ITD (n=12), and then shocked once with 120 joules of direct current. Epinephrine (0.04 mg/kg) and more CPR and shocks were used if ROSC was not achieved. Results (in mmHg) after 6 min of CPR with an active vs. sham ITD were: coronary perfusion pressure (PP) 20.8±1.2 vs. 21.0±0.9 (p=0.94); cerebral PP 8.8±1.0 vs. 10.0±0.9 (p=0.62); and end tidal CO2 38.1±1.5 and 37.1±1.3 (p=0.61). Peak and mean carotid artery blood flow (ml/min) was 323.9±15.2 vs. 256.6±21.1 (p=0.17) and 95.3±5.4 vs. 77.0±6.0 (p=0.22) with an active vs. sham ITD, respectively. Mean endotracheal pressures (mmHg) during chest recoil with an active vs. sham ITD were −2.0±0.5 vs. −0.2±0.2 (p<0.01). Arterial and venous blood gases were similar after 6 min of CPR between groups. ROSC, the primary survival endpoint for comparing the active vs. sham ITD, was 7/12 vs. 2/12 after 1 shock (p= 0.09), 12/12 vs. 5/12 after 2 shocks (p<0.01), and 12/12 vs. 7/12 after 3 shocks (p=0.04). With up to 14 shocks, 10/12 sham animals had a ROSC. All animals with ROSC lived for 30 min. There was no evidence of pulmonary edema or organ damage on autopsy with either ITD. Conclusions: After 6 min of CPR, LUCAS and active ITD resulted in lower mean airway pressures during chest recoil versus controls but hemodynamic findings were similar. However, ROSC was significantly easier to achieve with an active ITD; with up to 3 shocks twice as many animals were resuscitated with an active ITD. This benefit is most likely explained by carotid blood flows that trended higher with the active ITD. These positive findings and lack of any adverse outcomes support the safety and efficacy of this device combination.

Abstract P42: Active Compression Decompression-CPR in an Infant Manikin Model Using a Novel Adhesive Glove Device

Introduction: In animals Active Compression-Decompression(ACD)-CPR improves hemodynamics compared with standard CPR (S-CPR). We evaluated the feasibility of achieving ACD-CPR with a novel, simple and inexpensive Adhesive Glove Device (AGD) in an infant manikin model using two thumb (TT) chest compression. Hypothesis: AGD-ACD CPR provides better chest decompression compared to S-CPR in an infant manikin model without excessive rescuer fatigue. Methods: Laerdal ™ Baby ALS Trainer manikin was modified to digitally record compression pressure (CP), compression depth (CD) and decompression depth (DD). The thumb portion of two oven mitts were sewn together and a Velcro adhesive patch was stitched on the underside with an encircling adjustable strap for proper fit to create the AGD. An interlocking Velcro patch was glued to the manikin chest wall. Sixteen BLS or PALS certified healthcare providers were prospectively randomized to perform either two-thumb S-CPR or AGD-ACD-CPR for 5 minutes with a 30:2 compression:ventilation ratio using a crossover design. During AGD-ACD-CPR subjects were asked to pull up during chest decompression. Rescuer heart rate (HR), respiratory rate (RR), recovery time (RT) for HR/RR to return to baseline and actual compressions delivered per minute were recorded. Subjects were blinded to data recordings. Data (mean±SEM) was analyzed using 2 sided paired t-test; p-value ≤0.05 was considered significant. Results: Chest decompression was greater with AGD-ACD-CPR; the mean DD difference was 0.11±0.02 inches, p=<0.001. Compressions given per minute were 102±21 in S-CPR group vs. 96±16 in AGD-ACD-CPR group, p=0.04. In AGD-CPR 75% and in S-CPR only 12% of subjects achieved complete recoil to or beyond baseline. There was no significant difference in CD, CP, HR, RR and RT between the groups. Conclusions: Active decompression and improved recoil was achievable with the use of our simple, inexpensive AGD in this infant CPR model. Use of our device did not result in excessive rescuer fatigue compared to S-CPR. The clinical significance of 6 less compressions/minute in the AGD-CPR group needs to be determined.

Shock outcome prediction before and after CPR: A comparative study of manual and automated active compression–decompression CPR

We report on a study designed to compare the relative efficacy of manual CPR (M-CPR) and automated mechanical CPR (ACD-CPR) provided by an active compression-decompression (ACD) device. The ECG signals of out-of-hospital cardiac arrest patients of cardiac aetiology were analysed just prior to, and immediately after, cardiopulmonary resuscitation (CPR) to assess the likelihood of successful defibrillation at these time points. The cardioversion outcome prediction (COP) measure previously developed by our group was used to quantify the probability of return of spontaneous circulation (ROSC) after counter-shock and was used as a measure of the efficacy of CPR. An initial validation study using COP to predict shock outcome from the patient data set resulted in a performance of 60% specificity achieved at 100% sensitivity on a blind test of the data. This is comparable with previous studies and provided confidence in the robustness of the technique across hardware platforms. Significantly, the COP marker also displayed an ability to stratify according to outcomes: asystole, ventricular fibrillation (VF), pulseless electrical activity (PEA), normal sinus rhythm (NSR). We then used the validated COP marker to analyse the ECG data record just prior to and immediately after the chest compression segments. This was initially performed for 87 CPR segments where VF was both the pre- and post-CPR waveform. An increase in the mean COP values was found for both CPR types. A signed rank sum test found the increase due to manual CPR not to be significant (p>0.05) whereas the automated CPR was found to be significant (p<0.05). This increase was larger for the automated CPR (1.26, p=0.024) than for the manual CPR (0.99, p=0.124). These results indicate that the application of CPR does indeed provide beneficial preparation of the heart prior to defibrillation therapy whether manual or automated CPR is applied. The COP marker shows promise as a definitive, quantitative determinant of the immediate positive effect of both types of CPR regardless of the details of use. In work of a more exploratory nature we then used the validated COP marker to analyse the ECG pre- and post-CPR for all rhythm types (212 traces). We show a significant increase in the COP measure (p<0.001 in both cases) as indicated by a shift in the median COP marker distribution values. This increase was more pronounced for automated ACD-CPR than for manual CPR. However, a detailed statistical analysis carried out between the groups adjusted for pre-CPR value showed no significant difference between the two methods of CPR (p=0.20). Similarly, adjusting for length of CPR showed no significant difference between the groups. Secondary, subgroup analysis of the ECG according to the length of time for which CPR was performed showed that both types of CPR led to an increase in the likelihood of successful defibrillation after increasing durations of CPR, however results were less reliable after longer periods of continuous CPR.

Safety, feasibility, and hemodynamic and blood flow effects of active compression–decompression of thorax and abdomen in patients with cardiac arrest*

During closed chest compression for cardiac arrest, any increase in coronary perfusion pressure accounts for a proportional increase in myocardial blood flow and therefore the resuscitability of the patient. The objectives of this study were to evaluate the safety, feasibility, and hemodynamic effects of phased chest and abdominal compression-decompression and to compare it with mechanical chest compression during cardiopulmonary resuscitation. In this prospective, single-center, phase II study, we compared patients treated with the Datascope Lifestick Resuscitator with patients who had been treated with mechanical precordial compression. Emergency department of a tertiary care university hospital. We included 31 patients with cardiac arrest who had received cardiopulmonary resuscitation in the emergency department. The Lifestick device was used in 20 patients. In 11 patients, mechanical chest compression with the Thumper device was used as a control intervention. We evaluated the safety, feasibility, and hemodynamic effects of both interventions and observed, with the help of echocardiography, the mechanisms through which blood flow was generated. We found no significant difference between the use of the Lifestick device and standard chest compression with the Thumper device in resuscitations. Most operators regarded the Lifestick as a feasible alternative to the Thumper. We could observe a mean increase in coronary perfusion pressure of 9.33 mm Hg (interquartile range, 1.96-14.36; p = .08) and an increase of end-tidal CO2 of 10 mm Hg (interquartile range, 5-16; p = .003) (1333Pa [interquartile range, 665-2133]) during resuscitation with the Lifestick compared with using the Thumper. In this preliminary study, resuscitation with the Lifestick was found to be safe and feasible. The design of the study and small number of patients included in it limit the conclusions about the hemodynamic effects of the Lifestick.

Scientific Knowledge Gaps and Clinical Research Priorities for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Identified During the 2005 International Consensus Conference on ECC and CPR Science With Treatment Recommendations

Scientific Knowledge Gaps and Clinical Research Priorities for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Identified During the 2005 International Consensus Conference on ECC and CPR Science With Treatment Recommendations

Abstract 2230: Lower Extremity Counterpulsation During The Decompression Phase of CPR Improves Hemodynamics And Provides Continuous Forward Carotid Blood Flow.

Background: We hypothesize that lower extremity counterpulsations (LECP) during the decompression phase of CPR will increase diastolic aortic pressure without raising the intracranial pressure (ICP) and significantly increase forward carotid blood flow. Methods: In 6 (24±4Kg) pigs, 4 minutes of untreated VF were followed by 2 minutes epochs of standard (STD) CPR, STD +LECP, active compression decompression (ACD) +ITD and ACD + inspiratory impedance threshold device (ITD)+LECP. Compressions and ventilations were performed according to the 2005 AHA guidelines. A large blood pressure cuff that was circumferentially placed around the pig’s thighs avoiding the abdominal cavity was inflated with air to the point that manometer pressure started to rise. Compressions over the cuff were performed manually and synchronized with the thoracic decompression phase. The cuff was compressed up to 200mmHg. Basic hemodynamic parameters and common carotid blood flow (CCBF) (ml/min) were continuously measured. Cerebral perfusion pressure (CerPP) (mean arterial pressure - mean ICP) and CPP (diastolic AoP - diastolic RAP) were calculated at the end of the 2 minute epochs. Statistical analysis was performed with ANOVA. Results: LECP significantly increased diastolic aortic pressure, CPP and CerPP both when added on STD and on ACD+ITD CPR. The largest benefit was observed with ACD+ITD+LECP were there was a 2-fold increase in CPP and CerPP with a 2.5-fold increase in common carotid blood flow compared to STD CPR. LECP did not alter ICP. (Table 1 ). Decompression phase CCBF during ACD+ITD+LECP CPR was positive and reached pre cardiac arrest levels. Conclusion: LECP during thoracic decompression significantly augmented aortic diastolic pressure, CPP and CerPP without increasing the ICP . LECP led to a continuous positive cerebral perfusion pressure gradient during CPR cycles and in combination with ACD + ITD CPR common carotid blood flow reached pre-arrest levels. Hemodynamic Parameters

Use of an inspiratory impedance threshold valve during chest compressions without assisted ventilation may result in hypoxaemia

Although the concept of intermittent airway occlusion with the inspiratory impedance threshold valve (ITV) is a well-recognised strategy for improving efficiency of cardiopulmonary resuscitation (CPR), little is known about possible pulmonary side effects. After a baseline chest CT-scan, 24 pigs with beating hearts undergoing apnoeic oxygenation received an injection of a contrast medium and were then assigned randomly to either active compression-decompression CPR with ITV (ACD ITV CPR), ACD CPR alone, or standard-CPR with ITV (standard-ITV CPR), or standard-CPR alone. After a maximum of 5 min of chest compressions or if oxygen saturation dropped below 70%, the experiment was stopped, haemodynamic variables and blood gas values were measured, and another CT-scan was performed; all animals underwent a 30 min recovery-period and a third subsequent CT-scan. At baseline arterial oxygen saturation by pulse oxymetry was 99% in all four groups; in both the ACD ITV CPR and the standard-ITV CPR groups, arterial oxygen saturation dropped below 70% within 126+/-9s, whereas chest compressions in all ACD CPR and standard-CPR pigs were performed over 5 min (P<0.001). Before stopping chest compressions arterial oxygen pressure decreased in the ACD ITV CPR group from 426+/-96 to 42+/-8 mmHg while it decreased in the ACD CPR group only from 415+/-116 to 197+/-127 mmHg (P<0.001 between groups); in the standard-ITV CPR group arterial oxygen partial pressure decreased from 427+/-109 to 34+/-5 mmHg while oxygen partial pressure decreased only from 467+/-44 to 144+/-98 mmHg in the standard-CPR group (P<0.004 between groups). After the second CT scan arterial oxygen partial pressure decreased further to 19+/-2 mmHg in the ACD ITV CPR versus 210+/-41 mmHg in the ACD CPR group; to 20+/-2 mmHg in the standard-ITV CPR versus 148+/-33 mmHg in the standard-CPR group. Lung-density values (Hounsfield units) were significantly higher in the ACD ITV CPR versus ACD CPR group (-134+/-54 versus -330+/-77) and standard-ITV CPR versus standard-CPR group (-98+/-50 versus -387+/-42). After a 30 min recovery-period, there were no significant differences in arterial oxygen partial pressure (ACD ITV CPR 275+/-110 mmHg versus ACD CPR 379+/-111 mmHg and standard-ITV CPR 265+/-138 mmHg versus standard CPR 367+/-55 mmHg). Furthermore, there were no differences in lung density values between groups after 30 min of recovery. In this animal model with a beating heart, intermittent airway obstruction through an ITV combined with apnoeic oxygenation and without active ventilation resulted in hypoxaemia due to transiently impaired lung function.

Use of an impedance threshold valve for cardiac arrest during cardiopulmonary resuscitation:a new cardiopulmonary resuscitation method

心肺复苏(cardiopulmonary resuscitation, CPR)成功率和存活率仍然很低,主要原因是CPR期间回心血量少,心脏和脑灌注不足.增加胸内负压的措施和器材明显提高心肺复苏的效果[1～4].近来,Lurie等[5～10]又研制出在胸壁放松时增加胸内负压的阻力单向活瓣(inspiratory impedance threshold valve(device),ITV or ITD),使心肺复苏的效果进一步提高。

Feasibility study of the wave disk micro-engine operation

The development of micro turbine engines has been strongly intensified in recent years. Since turbo-component efficiency has become very low due to the downsizing effect, the micro wave rotor is expected to be applied for the improvement of the performance of ultra-micro gas turbines, increasing the cycle pressure ratio. But wave rotors can also be used in another configuration. Here replacement of steady flow engine components by unsteady flow devices is proposed and analyzed. Applying a combustion chamber only and using oblique blades to form the rotor cells, net power can be taken from the rotor. In that way the use of an inefficient, micro-scale turbo unit can be omitted. Conventional construction of unsteady devices in the form of a wave rotor cannot be realized in MEMS technology. The new idea of a wave disk gives the possibility of an easy implementation of a wave engine in MEMS technology. In the proposed solution the wave disk plays the role of an active compression–decompression unit and torque generator. Appropriate port geometry with straight or oblique blades forming the disk channels generates torque. The engine disk rotates with a speed much lower than the conventional turbo unit and simplifies the bearing problem. Also the construction of an electric generator could be simpler. This paper presents the proposed flow schemes, thermodynamic cycle, exemplary engine construction and some preliminary results of simulation of the MEMS wave engine utilizing the wave disk geometry.

“CAPR” study part 1: concordance rate of suspected (out-of-hospital) and confirmed (hospital) cause of cardiac arrest

Purpose: There are 200 patients projected in the study who were resuscitated using different methods of circulation replacement: standard chest compressions (S-CPR), active compression-decompression (ACD-CPR), interposed abdominal compressions (IAC-CPR) and their combinations.

Comparison of two mechanical chest compression devices in out-of-hospital cardiac arrests

Purpose of the study: Early start of high quality chest compressions without interruptions is of major importance for survival after cardiac arrest. Manual compressions are unfortunately of variable quality and very dependent on the rescuer [1]. We wanted to compare two different commercially available mechanical chest compression devices (m-CCD) with manual chest compressions. Methods: A load-distributing band compression device (AutoPulse) was compared to an active compression–decompression piston device (LUCAS).

Rapid Induction of Cerebral Hypothermia Is Enhanced With Active Compression-Decompression Plus Inspiratory Impedance Threshold Device Cardiopulmonary Resusitation in a Porcine Model of Cardiac Arrest

A rapid, ice-cold saline flush combined with active compression-decompression (ACD) plus an inspiratory impedance threshold device (ITD) cardiopulmonary resusitation (CPR) will cool brain tissue more effectively than with standard CPR (S-CPR) during cardiac arrest (CA). Early institution of hypothermia after CPR and return of spontaneous circulation improves survival and outcomes after CA in humans. Ventricular fibrillation (VF) was induced for 8 min in anesthetized and tracheally intubated pigs. Pigs were randomized to receive either ACD + ITD CPR (n = 8) or S-CPR (n = 8). After 2 min of CPR, 30 ml/kg ice-cold saline (3 degrees C) was infused over the next 3 min of CPR via femoral vein followed by up to three defibrillation attempts (150 J, biphasic). If VF persisted, epinephrine (40 microg/kg) and vasopressin (0.3 U/kg) were administered followed by three additional defibrillation attempts. Hemodynamic variables and temperatures were continuously recorded. All ACD + ITD CPR pigs (8 of 8) survived (defined as 15 min of return of spontaneous circulation [ROSC]) versus 3 of 8 pigs with S-CPR (p < 0.05). In survivors, brain temperature (degrees C) measured at 2-cm depth in brain cortex 1 min after ROSC decreased from 37.6 +/- 0.2 to 35.8 +/- 0.3 in ACD + ITD CPR versus 37.8 +/- 0.2 to 37.3 +/- 0.3 in S-CPR (p < 0.005). Immediately before defibrillation: 1) right atrial systolic/diastolic pressures (mm Hg) were lower (85 +/- 19, 4 +/- 1) in ACD + ITD CPR than S-CPR pigs (141 +/- 12, 8 +/- 3, p < 0.01); and 2) coronary perfusion pressures (mm Hg) were higher in ACD + ITD CPR (28.3 +/- 2) than S-CPR pigs (17.4 +/- 3, p < 0.01). A rapid ice-cold saline infusion combined with ACD + ITD CPR during cardiac arrest induces cerebral hypothermia more rapidly immediately after ROSC than with S-CPR.

Design of near-optimal waveforms for chest and abdominal compression and decompression in CPR using computer-simulated evolution

To discover design principles underlying the optimal waveforms for external chest and abdominal compression and decompression during cardiac arrest and cardiopulmonary resuscitation (CPR). A 14-compartment mathematical model of the human cardiopulmonary system is used to test successive generations of randomly mutated external compression waveforms during cardiac arrest and resuscitation. Mutated waveforms that produced superior mean perfusion pressure became parents for the next generation. Selection was based upon either systemic perfusion pressure (SPP = thoracic aortic minus right atrial pressure) or upon coronary perfusion pressure (CPP = thoracic aortic pressure minus myocardial wall pressure). After simulations of 64,414 individual CPR episodes, 40 highly evolved waveforms were characterized in terms of frequency, duty cycle, and phase. A simple, practical compression technique was then designed by combining evolved features with a constant rate of 80 min(-1) and duty cycle of 50%. All ultimate surviving waveforms included reciprocal compression and decompression of the chest and the abdomen to the maximum allowable extent. The evolved waveforms produced 1.5-3 times the mean perfusion pressure of standard CPR and greater perfusion pressure than other forms of modified CPR reported heretofore, including active compression-decompression (ACD)+ITV and interposed abdominal compression (IAC)-CPR. When SPP was maximized by evolution, the chest compression/abdominal decompression phase was near 70% of cycle time. When CPP was maximized, the abdominal compression/chest decompression phase was near 30% of cycle time. Near-maximal SPP/CPP of 60/21 mmHg (forward flow 3.8 L/min) occurred at a compromise compression frequency of 80 min(-1) and duty cycle for chest compression of 50%. Optimized waveforms for thoraco-abdominal compression and decompression include previously discovered features of active decompression and interposed abdominal compression. These waveforms can be used by manual (Lifestick-like) and mechanical (vest-like) devices to achieve short periods of near normal blood perfusion non-invasively during cardiac arrest.

A case of hypothermic cardiac arrest treated with an external chest compression device (LUCAS) during transport to re-warming

The recommended treatment for severe hypothermia with circulatory collapse is re-warming using cardiopulmonary by-pass. This may require transporting a patient to hospital with on-going cardiopulmonary resuscitation (CPR). Manual CPR during patient transport may result in sub-optimal chest compressions and can be a hazard for the ambulance crew. We report a case of a patient with a core temperature of 22.2 °C and crew-witnessed cardiac arrest due to hypothermia. After unsuccessful initial resuscitation he was transported to hospital for re-warming with cardiopulmonary by-pass. CPR was continued during transport using a mechanical active compression–decompression device (the LUCAS-device). During cardiopulmonary by-pass ROSC was achieved after 90 min of cardiac arrest. The patient recovered with a cerebral performance category of 3. Using a mechanical device for chest compressions during transport of a hypothermic patient with on-going CPR is feasible, effective and safe.

Mechanical devices for cardiopulmonary resuscitation

For over 40 years, manual chest compressions have been the foundation of cardiopulmonary resuscitation and recent studies have clearly reconfirmed the hemodynamic significance of delivering consistent, high-quality, infrequently-interrupted chest compressions. However, there remain multiple inadequacies in the actual delivery of manual chest compressions during cardiopulmonary resuscitation. One potential solution is use of adjunct mechanical devices. Two different methods of accessory chest compression techniques recently have demonstrated enhanced short-term survival. The active compression-decompression device is a hand-held, manually operated suction device applied to the center of the chest wall. In tandem with an impedance threshold (airway) device, active compression-decompression has shown a 65% improvement in 24-hour survival rates (compared with standard cardiopulmonary resuscitation) in a randomized out-of-hospital clinical trial (n = 210). The second device, called Auto-Pulse CPR is an automated machine that uses a load-distributing, broad compression band that is applied across the entire anterior chest. A recent out-of-hospital retrospective case-control study (n = 162) also revealed improved short-term survival. High quality chest compressions during cardiopulmonary resuscitation are critical elements in effecting successful resuscitation following a cardiac arrest. Recent studies utilizing adjunct mechanical devices have not only revealed significant increases in the effectiveness of chest compressions, including improved hemodynamics in both animal models and human studies, but also improvements in short-term human survival in the clinical setting. It is hoped that these promising findings will eventually be corroborated in terms of improved neurologically intact, long-term patient survival. Clinical trials are currently underway to validate such efficacy.

Use of an inspiratory impedance threshold device on a facemask and endotracheal tube to reduce intrathoracic pressures during the decompression phase of active compression–decompression cardiopulmonary resuscitation

Use of an inspiratory impedance threshold device (ITD) significantly increases coronary perfusion pressures and survival in patients ventilated with an endotracheal tube (ETT) during active compression-decompression cardiopulmonary resuscitation. We tested the hypothesis that the ITD could lower intratracheal pressures when attached to either a facemask or ETT. An active and sham ITD were randomly applied first to a facemask and then to an ETT during active compression-decompression cardiopulmonary resuscitation in 13 out-of-hospital cardiac arrest patients in a randomized, double-blinded, prospective clinical trial. The compression-to-bag-valve ventilation ratio was 15:2. Airway pressures (surrogate for intrathoracic pressure) were measured with a pressure transducer. A sham and an active ITD were used for 1 min each in a randomized order, first on a facemask and then on an ETT. Statistical analyses were made using Friedman's and Wilcoxon's rank-sum tests. For the primary end point, mean +/- sd maximum negative intrathoracic pressures (mm Hg) during the decompression phase of cardiopulmonary resuscitation were -1.0 +/- 0.73 mm Hg with a sham vs. -4.6 +/- 3.7 mm Hg with an active ITD on the facemask (p = .003) and -1.3 +/- 1.3 mm Hg with a sham ITD vs. -7.3 +/- 4.5 mm Hg with an active ITD on an ETT (p = .0009). Decompression phase airway pressures with the facemask and ETT were not statistically different. Use of an active ITD attached to a facemask or an ETT resulted in a significantly lower negative intratracheal pressure during the decompression phase of active compression-decompression cardiopulmonary resuscitation when compared with controls. Airway pressures with an ITD on either a facemask or ETT were similar. The ITD-facemask combination was practical and enables rapid deployment of this life-saving technology.

Report From the Meeting of the Circulatory System Devices Panel of the Food and Drug Administration Center for Devices and Radiologic Health

The US Food and Drug Administration (FDA) Circulatory System Devices Panel met to discuss the type of data required to effectively evaluate the performance of cardiopulmonary resuscitation (CPR) and hypothermia devices for cardiac arrest patients. Advisory panels make nonbinding recommendations to the FDA. The era of modern CPR began in the 1960s, when mouth-to-mouth ventilation combined with forceful chest compressions were first used together to attempt to resuscitate victims of cardiopulmonary arrest. Unfortunately, despite the promise of a variety of pharmacological, electrical, and mechanical therapies during and after administration of CPR, meaningful improvements in cardiac arrest survival have been difficult to achieve. Earlier generations of CPR devices are designed to assist the rescuer in the performance of CPR. These devices, for example, may compress the chest at a fixed rate and compression depth, or they may provide audible or visual indicators to assist the rescuer with compliance with published CPR guidelines. In general, regulatory guidelines do not require clinical data for these devices as long as they are similar in design and technology to previously marketed “predicate” devices. More than 30 devices for external compression and/or timing assistance during CPR have been cleared for marketing by the FDA. Devices intended to enhance a clinical aspect of CPR, in contrast to devices designed simply to assist the rescuer in the performance of CPR, require clinical data to support approval of the device. These devices, such as those providing interposed abdominal compression, circumferential chest compression, or active compression-decompression, have focused primarily on enhancing hemodynamics during CPR. Despite great interest in improving CPR survival rates, no device intended to enhance hemodynamics during CPR has been approved by the FDA for marketing in the United States. The Circulatory System Devices Panel was asked to discuss and make recommendations about the type of clinical data …

Die notfallmedizinischen „Highlights” der vergangenen Monate - Schädel-Hirn-Trauma, Polytrauma und Kreislaufstillstand

According to scientific publications focusing on emergency medicine and published in international journals in the past few months, new and clinically important results can be identified. In patients with severe head trauma (SHT), application of hypertonic solutions is possible; long term outcome, however, is not improved by this measure. Prehospital capnometry is important, because otherwise up to 40 % of all mechanically ventilated patients are hypoventilated. In a study in 200 patients with prehospital cardiac arrest and ventricular fibrillation as initial cardiac rhythm, subgroup analysis (alarm-response time > 5 min) showed an increase in survival rate (14 % vs. 2 %), if defibrillation was proceeded by 3 min of conventional cardiopulmonary resuscitation (CPR) for reperfusion. If ACD ("active compression decompression")-CPR is combined with a specific ventilatory valve ("inspiratory impedance threshold device", ITD) which does not allow passive inspiration, survival rate after cardiac arrest is increased for up to 24 h. Such a device facilitates an increase in venous return to the heart during decompression of the thorax. High-dose adrenalin for intrahospital CPR in children is not associated with better survival but with worse outcome. Comparison of an emergency medical service (EMS) system from U.K. with paramedics and a physician-staffed German EMS system demonstrated that survival rate following prehospital cardiac arrest is markedly increased with doctors on board. The European multicentre trial comparing vasopressin vs. adrenalin as first vasopressor during CPR in 1219 patients did not reveal any differences between both groups. In subgroup analyses of patients with asystoly and prolonged CPR, vasopressin was superior without being associated with a benefit on neurological outcome. Further subgroup analyses revealed beneficial effects of amiodarone and thrombolysis during CPR. Thrombolysis during CPR apears to be associated with an increased rate of haemodynamic stabilisation without increased risk of bleeding complications. In a very clear advisory statement, the "International Liaison Committee on Resuscitation" (ILCOR) has recommended mild therapeutic hypothermia (i. e., cooling of cardiac arrest victims to 32 - 34 degrees C central body temperature for 12 - 24 h following cardiac arrest of cardiac etiology) not only for unconciuous patients with ventricular fibrillation as initial prehospital rhythm, but also for all other adult patients (other rhythms, intrahospital CPR) following cardiac arrest. In randomised controlled clinical trials, this therapy has markedly improved survival rate and neurological outcome. Such therapeutic cooling can be initiated nearly everywhere and with simple methods - like the infusion of ice-cold cristalloid solutions.

Active Compression-Decompression Plus Inspiratory Impedance Threshold Device CPR Results in More Efficient Cold Transfer between Blood and Brain Than Standard CPR During Cardiac Arrest

Translations: Abstracts from the 15th Annual Pediatric Critical Care Colloquium: Oral Abstract Presentations