Active Compression-decompression Research Articles

Abstract 385: Comparison of Rapid Implementation of Automated Head and Thorax Elevation With Active Compression Decompression Cardiopulmonary Resuscitation and an Impedance Threshold Device versus National Outcome Data: A Prospective Observational Study

Background: Pre-clinical work has shown automated head and thorax elevation with active compression decompression CPR and an impedance threshold device (AHUP-CPR) improved 24-hour neurological survival. Propensity matched studies of out-of-hospital-cardiac arrest (OHCA) patients have shown a time dependent association between survival to hospital discharge (SHD) and application of AHUP CPR.Hypothesis: Rapid application of AHUP CPR for OHCA will have a higher incidence of SHD compared to national data. Methods: This is an ongoing prospective observational study of patients from an AHUP-CPR registry of non-traumatic adult OHCA receiving AHUP CPR as part of first responder care. OHCA patients from pre-hospital sites that consistently implemented rapid AHUP CPR were included. Patient demographics, arrest characteristics, ROSC, SHD, and SHD with favorable neurological function, defined as a Cerebral Performance Category score of 1 or 2, were recorded. Data are reported as means ± SD. Combined 2021 and 2022 data from the Cardiac Arrest Registry to Enhance Survival (CARES) were used for comparison of the primary study endpoint, SHD, and secondary endpoints. Chi-square testing was used to compare outcomes. Results: Of 11 registry sites, 7 (US States AL, FL, IL, MN, OK, TN, VA) met inclusion criteria and 1457 patients from January 2020 to June 2023 were enrolled. Average age was 65 ± 16.4 years, 61.8% (901) were male, and 71% (1035) received AHUP CPR. Average time (mm:ss) from 9-1-1 call to start of CPR was 9:52 (6:47) and time to start of AHUP CPR was 12:59 (5:51). Presenting rhythms were: asystole 47.8% (696), PEA 25.8% (376), and VF 20.5% (298). For all AHUP patients, SHD was 13.6% (198) versus 9.2% (26316/286525) for CARES (p < 0.0001). SHD with favorable neurological function was higher for AHUP (10.3% (150) versus 7.3% for CARES (20889), p < 0.0001) and ROSC (29.4% (428) vs 27.0% (77301), p = 0.039). Conclusions: In an unadjusted analysis, the incidence of SHD, ROSC, and neurologically favorable SHD with rapid implementation of AHUP-CPR was higher than nationally reported data. These results support prior findings of a time sensitive association between survival and time to AHUP-CPR. Additional analyses and study are needed for confirmation.

Abstract 141: Automated Head-Up Cardiopulmonary Resuscitation Increased End Tidal Co2 in Patients With Out-of-Hospital Cardiac Arrest Compared With Conventional CPR: A Prospective Before-After Interventional Study

Background: Little is known in humans about the physiological effects of the combination of automated Head-Up cardiopulmonary resuscitation CPR, active compression-decompression CPR and an impedance threshold device (ITD). This new approach, termed AHUP-CPR, improves perfusion of vital organs and lowers intracranial pressure compared with conventional (C)CPR in animal models of cardiac arrest. This study tested the hypothesis that AHUP-CPR treatment would increase end tidal CO2 (ETCO2), a circulation surrogate, more than C-CPR in out-of-hospital cardiac arrest (OHCA) patients. Method: Prospective before-after interventional study of witnessed OHCA patients. C-CPR and AHUP-CPR were performed by firefighters who measured ETCO2. AHUP-CPR was delivered using a LUCAS AD (5 cm of compression and 3 cm active decompression) (Stryker Medical, USA), an EleGARD Patient Positioning System (AdvancedCPR Solutions, USA), and an ITD (ResQPOD-16, Zoll, USA). The study was performed in the greater Grenoble France region in four different fire stations. The primary endpoint was the measurement of maximum EtCO2 during CPR. Results are presented as mean ± standard deviation. Results: Baseline characteristics (age, sex, arrest location, initial rhythm, bystander CPR, witnessed) were not statistically different between groups.EtCO2 was higher for patients treated with AHUP-CPR (n=63) compared to the C-CPR (n=59) (41±18 vs. 30.2 mmHg, p<0.001). This difference was significant for shockable (45±13 vs. 34±12 mmHg, p=0.03) and non-shockable (40±19 vs. 28±13 mmHg, p=0.004) rhythms, respectively. The calculated difference between the maximum and first recorded ETCO2 values was 6.3 ± 20.4 in the C-CPR arm versus 21.1 ± 20.6 in the AHUP-CPR group (P<0.001). A total of 29% (n=18) of the AHUP patients vs. 22 % (n=13) were admitted alive to the hospital (P=0.34). Conclusion: Results from this first prospective clinical trial on AHUP-CPR demonstrated that ETCO2 values were significantly higher after AHUP-CPR versus C-CPR, regardless of the presenting rhythm. Using ETCO2 as a surrogate for circulation, these findings confirm animal studies showing AHUP-CPR provides significantly more vital organ blood flow to patients in OHCA compared with C-CPR.

Abstract 320: Survival and Neurological Function With Rapid versus Delayed Automated Head-Up CPR in a Porcine Model of Prolonged Cardiac Arrest

Background: Rapid Basic Life Support (BLS) treatment with controlled sequential elevation of the head and thorax, active compression-decompression CPR, and an impedance threshold device, collectively termed automated Head Up Position (AHUP)-CPR, is associated with better outcomes versus conventional CPR (C-CPR) in animal models and human observational studies. Hypothesis: Rapid AHUP-CPR should improve survival and neurological function vs rapid C-CPR followed by delayed AHUP-CPR. Aim: Determine if AHUP-CPR should be initiated as a BLS or ALS intervention. Methods: Male and female farm pigs (n=22) weighing~40kg were anesthetized and ventilated. Central venous and aortic pressures, as well as end-tidal CO2 (ETCO2) and cerebral oximetry (rSO2) were measured continuously. After 15 min of untreated VF, pigs were randomized to either rapid AHUP-CPR for 25 min or 10 min of C-CPR followed by 15 min of AHUP-CPR. Pigs received intravenous epinephrine and amiodarone after 24 min of CPR and were defibrillated 60 sec later. For the primary endpoint, 24-hour neurologic function, a veterinarian blinded to the CPR intervention assessed pigs using a Neurological Deficit Score (0 = normal and 260 = worst deficit score or death). Secondary outcomes included 24-hour survival rates and hemodynamic parameters. Data were expressed as mean ± SD. Statistical significance was determined by log-rank, Mann-Whitney-U and unpaired t-tests. Results: Sustained return of spontaneous circulation was achieved in 10/11 pigs with rapid AHUP-CPR vs 6/11 with delayed AHUP-CPR and cumulative 24-hour survival rates were 45.5% (5/11) vs 9.1% (1/11), respectively (p=0.01). Neurological Deficit Scores were 202.7 ± 80.3 with rapid AHUP-CPR vs 259.1 ± 3.0 with delayed AHUP-CPR group (p=0.04). Ten minutes after initiating CPR, ETCO2 (mmHg) was 45.0 ± 3.8 vs 26.9 ± 5.4 (p<0.001), and rSO2 (%) was 67.3 ± 3.9 vs 61.4 ± 6.3 (p=0.01) with rapid AHUP-CPR vs delayed AHUP, respectively. Conclusion: In a severe and prolonged model of porcine cardiac arrest, rapid AHUP-CPR, delivered as a BLS intervention, significantly improved the survival rate, neurological function and hemodynamics when compared with rapid C-CPR followed by delayed AHUP-CPR.

Abstract 321: Manual vs Automated Ventilation During Automated Head-Up Cardiopulmonary Resuscitation in a Porcine Model

Background: The efficacy of mechanical ventilation during CPR with the combination of active compression-decompression, an impedance threshold device, and head-up positioning, collectively termed automated head-up (AHUP)-CPR, is unknown. Hypothesis: Hemodynamic and ventilatory parameters will be similar with manual bag ventilation (MBV) versus automated bag ventilation (ABV) during AHUP-CPR in a porcine model of cardiac arrest. Aim: Assess the proof-of-concept that ABV is safe and effective during AHUP-CPR. Methods: Nine male and female swine (~40 kg) were anesthetized and ventilated. VF was induced and left untreated for 8 min. AHUP-CPR was performed at 105 compressions/min for 7 min using MBV, followed by 6 min using an automated mechanical bag compressor to deliver 10ml/kg of tidal volume (TV) over 1 sec at 10 breaths/min. Pigs were randomized during ABV to a synchronized (Sync) breath delivered at the start of decompression or an asynchronous (Async) breath. Cerebral perfusion pressure, coronary perfusion pressure, end-tidal CO2, intracranial pressure, esophageal intrathoracic pressure, peak airway pressure (PAP), inspiratory and expiratory TVs as well as arterial blood gases were continuously measured. Values (mean ± SD) were compared by paired and unpaired student’s t-tests with a Bonferroni correction. Results: Parameters during the last minute of MBV and ABV are summarized in the table. No significant differences were observed in hemodynamic and ventilatory parameters, except for PAP and pO2 values which were significantly lower with MBV. No significant differences were also observed between the Sync and Async ABV modes. Conclusion: Manual and mechanical ventilation resulted in overall similar physiological effects. The clinical relevance of the observed significant differences in PAP and pO2 is unclear. Additional studies are warranted to further assess the safety and effectiveness of mechanical ventilation during AHUP-CPR.

Cardiac Arrest Bundle of cARE Trial (CABARET) survey of current UK neuroprotective CPR practice

Despite low out of hospital cardiac arrest (OOHCA) survival rates within the UK, animal studies hint at improved cerebral blood flow via a bundled neuroprotective CPR approach. The CABARET study introduces three key devices: the Head Up Position (HUP), Active Compression/Decompression (ACD) CPR, and the Impedance Threshold Device (ITD). A survey involving 27 UK pre-hospital critical care services indicated none are using these interventions widely, either alone or bundled. The CABARET team is now initiating a pilot study to investigate the feasibility of this CPR bundle, aiming to fill the prevailing evidence void in resuscitation research.

A Review of CPR Augmentation Devices.

The study aims to assess cardiopulmonary resuscitation (CPR) outcomes in cardiac arrest patients when using CPR augmentation devices, such as the ZOLL ResQCPR system (Chelmsford, MA) or its components ResQPUMP and ResQPOD, which are manual active compression-decompression (ACD) deviceand impedance threshold device(ITD), respectively. The analysis included a Google Scholar-based literature review that took place between January 2015 and March 2023 and included recent publications with PubMed IDs or widely cited articles to assess the effectiveness of the ResQPUMP and ResQPOD or similar devices. This review also includes studies quoted by ZOLL, but those were not considered in our conclusion since the authors were employed by ZOLL. We found that in a study on human cadavers, the force of decompression increased the chest compliance of the chest wall by 30%-50% (p<0.05). Essentially, active compression-decompression improved the return of spontaneous circulation (ROSC) with meaningful neurologic outcomes by 50% in a blinded, randomized, and controlled human trial (n=1,653; p<0.02). The main study on the ResQPOD had a controversial human data pool with one randomized and controlled study arguing for no significant difference with or without the device (n=8,718; p=0.71). However, a post hoc analysis and the reorganization of the data by CPR quality demonstrated significance (n decreased to 2,799, reported in odds ratio without specific p-values). In conclusion to the limited number of studies presented, any manual ACD deviceis a great alternative to standard cardiopulmonary resuscitation regarding survivability with good neurologic function and should be utilized in prehospital emergency medical services and hospital emergency departments. ITDs are still controversial but promising with more future data.

High central venous pressure amplitude predicts successful defibrillation in a porcine model of cardiac arrest

AimIncreasing venous return during cardiopulmonary resuscitation (CPR) has been shown to improve hemodynamics during CPR and outcomes following cardiac arrest (CA). We hypothesized that a high central venous pressure amplitude (CVP-A), the difference between the maximum and minimum central venous pressure during chest compressions, could serve as a robust predictor of return of spontaneous circulation (ROSC) in addition to traditional measurements of coronary perfusion pressure (CPP) and end-tidal CO2 (etCO2) in a porcine model of CA. MethodsAfter 10 min of ventricular fibrillation, 9 anesthetized and intubated female pigs received mechanical chest compressions with active compression/decompression (ACD) and an impedance threshold device (ITD). CPP, CVP-A and etCO2 were measured continuously. All groups received biphasic defibrillation (200 J) at minute 4 of CPR and were classified into two groups (ROSC, NO ROSC). Mean values were analyzed over 3 min before defibrillation by repeated-measures Analysis of Variance and receiver operating characteristic (ROC). ResultsFive animals out of 9 experienced ROSC. CVP-A showed a statistically significant difference (p = 0.003) between the two groups during 3 min of CPR before defibrillation compared to CPP (p = 0.056) and etCO2 (p = 0.064). Areas-under-the-curve in ROC analysis for CVP-A, CPP and etCO2 were 0.94 (95% Confidence Interval 0.86, 1.00), 0.74 (0.54, 0.95) and 0.78 (0.50, 1.00), respectively. ConclusionIn our study, CVP-A was a potentially useful predictor of successful defibrillation and return of spontaneous circulation. Overall, CVP-A could serve as a marker for prediction of ROSC with increased venous return and thereby monitoring the beneficial effects of ACD and ITD.

10: PROFOUND INCREASES IN NEUROINTACT PATIENT SURVIVAL FOR NONSHOCKABLE (ASYSTOLE/PEA) CARDIAC ARRESTS

Introduction: The neuroprotective approach to basic CPR (NPCPR) using adjuncts to lower ICP and enhance cardiac venous return (including gradual head/torso-up positioning [HTup]), has significantly improved overall neuro-intact survival (SURVni) for out-of-hospital cardiac arrest (OHCA) patients (Resuscitation 2022). However, as ~80% of OHCA cases have non-shockable (asystole/PEA) presentations (N-Sh) and attendant grim prognoses, the specific aim was to confirm if (and by how much) NPCPR-improved SURVni applies to N-Sh OHCA cases. Methods: Five U.S. EMS agencies using NPCPR prospectively tracked SURVni and all known SURVni related factors: age; sex; witnessed arrest; bystander CPR; T-CPR (time from 9-1-1 call to EMS crews starting CPR); initial ECG; and T-htup (9-1-1 call to HTup start). An automated HTup device (occiput raised to 22cm over several mins) was combined with active compression-decompression and impedance threshold devices (all FDA-cleared). For rigorous comparisons, conventional CPR (C-CPR) controls were derived from 2 large (n=10,053) published NIH trials involving (criteria-compliant) high-performance EMS systems (eg, recorded /monitored /reported CPR quality). Using propensity scoring for the pivotal SURVni factors, 353 N-Sh NPCPR patients were well-matched with 353 N-Sh C-CPR patients and compared for SURVni (mRS < or =3 or CPC 1 or 2). Results: For both 353 NPCPR patients and 353 controls: 2/3 were in asystole; mean ages 66; 8 min median T-CPR (IQR 6-10). Median T-htup = 11 min (IQR 9-15). Before propensity matching, the overall unadjusted OR [95%CI] for NPCPR SURVni (vs C-CPR) was 3.09 [1.64-5.81] and 3.87 [1.27-11.78] after matching (incl. responses >20 min). Analogous to AEDs in shockable OHCA, the earlier NPCPR was applied, SURVni improved: NPCPR SURVni was >10-fold higher, 6.1% v 0.6% (10/165 v 1/165) when T-htup < 11 mins [OR 10.59;1.34-83.63] or (cumulatively) 4.6% v 0.4% (13/281 v 1/281) if < 16 mins [OR 13.58;1.76-104.54]. Conclusions: Even compared to top-performing EMS systems, NPCPR, especially applied early, was associated with markedly-improved SURVni odds for asystole/PEA patients, with or without propensity score matching. As most EMS systems can initiate CPR for the majority of patients in < 12 min, NPCPR may potentially salvage many more lives than previously projected.

Abstract 169: End Tidal CO2 In Multimodal Vest CPR

Introduction: Circumferential constriction vest CPR is more effective at creating forward blood flow than traditional sternal compression only CPR. Active compression-decompression plus the impedance threshold device CPR (ACD-ITD-CPR) incorporates multiple hemodynamic pump mechanisms and also appears more effective. We have developed a new multimodal CPR that combines vest CPR with additional pump mechanisms, one of which is abdominal counterpulsation. Traditional coronary perfusion pressure (CPP) has not been validated during CPR that incorporates compression modalities applied during the relaxation phase. End tidal carbon dioxide (ET-CO2), however, is an indicator of forward blood flow during CPR that is unaffected by relaxation phase compressions. Hypothesis: Multimodal vest CPR that incorporates multiple pump mechanisms may be more effective than standard alternatives as indicated by ET-CO2. Methods: Utilizing a porcine model of ventricular fibrillation, we measured ET-CO2 in: 1) traditional sternal compression CPR (S-CPR), 2) active compression-decompression plus the impedance threshold device CPR (ACD-ITD-CPR) and 3) a new multimodal CPR comprised of circumferential constriction plus abdominal counterpulsation and active sternal decompression (MM-CPR) . After onset of cardiac arrest, 1 min. epochs of each CPR were randomly performed. Results: Seven experiments were performed with a mean number of epochs per experiment of 7. The mean (M + SD) ET-CO2 for S-CPR was 9 + 3 mmHg, for ACD-ITD-CPR 12 + 6, and for MM-CPR 19+8 (P&lt;.05). Conclusions: Multimodal CPR comprising circumferential constriction plus abdominal counterpulsation and active sternal decompression is a promising new type of non-invasive circulatory support.

Abstract 187: Synergy Of Elevation Of The Head And Thorax And Resuscitative Endovascular Balloon Occlusion Of The Aorta In A Porcine Model Of Prolonged Cardiac Arrest: A Pilot Study

Background: Two new approaches to improve cardiac arrest outcomes, active compression-decompression (ACD) with an impedance threshold device (ITD) CPR with automated Head Up Positioning, (AHUP-CPR), and resuscitative endovascular balloon occlusion (REBOA) have been studied separately but never together. This was a pilot animal study exploring potential hemodynamic synergy of AHUP+ REBOA after prolonged CPR. Methods: Farm pigs (~40 kg) were sedated, intubated, and anesthetized. Central venous, and intracranial pressures were measured. Bilateral femoral arterial access was obtained for arterial pressure measurement and REBOA placement in the proximal thoracic aorta. Hemodynamics were measured with solid state pressure catheters. The arterial pressure catheter was placed in the thoracic aorta and confirmed via fluoroscopy. After 35 minutes of AHUP CPR, animals underwent two-minute epochs of AHUP-CPR, AHUP+REBOA CPR, ACD+ITD CPR flat + REBOA, and ACD+ITD CPR flat. Pressures are reported as mean (mmHg) ± standard deviation. Comparison testing was not performed in this pilot study. Results: In 4 pigs after 35 minutes, the AHUP CPR cerebral perfusion pressure (CerPP) was 21.1 ± 10.4, aortic compression (AOC) and decompression (AOD) pressures were 43.4 ± 9.1 and 14.1 ± 9.4, and intracranial compression (ICP) and decompression (DIP) pressures were 9.2 ± 2.7 and 6.5 ± 3.6, respectively. With AHUP+REBOA, CerPP was 39.0 ± 8.7, AOC and AOD pressures were 69.2 ± 10.7 and 21.0 ± 8.9, and ICP and DIP 9.7 ± 2.6 and 5.8 ± 2.9. The ACD+ITD CPR flat + REBOA CerPP was 21.7 ± 11.8, AOC and AOD pressures were 57.1 ± 9.5, and ICP and DIP were 20.5 ± 4.1 and 15.9 ± 3.2. The ACD+ITD CPR flat CerPP was 11.2 ± 7.5, AOC and AOD pressures were 38.8 ± 6.7 and 15.9 ± 6.6, and ICP and DIB were 17.4 ± 1.1 and 15.0 ± 1.6. A representative study tracing is shown. Conclusions: The combination of AHUP CPR with REBOA is feasible and may work synergistically after prolonged resuscitation in this ongoing animal study.

Abstract 11244: Active Decompression During Device Assisted Elevation of the Head and Thorax, an Impedance Threshold Device, and Active Compression Decompression Cardiopulmonary Resuscitation is Needed for Sustained Hemodynamic Benefit in a Porcine Model of Prolonged Cardiac Arrest

Introduction: Active compression decompression cardiopulmonary resuscitation (CPR), an impedance threshold device (ITD), and automated device-assisted controlled head up positioning, collectively termed AHUP CPR, work synergistically to lower intracranial pressure, augment venous return to the heart and significantly improve neurological survival versus conventional (C)-CPR in animals and patients in cardiac arrest. The current study focused on the role of active decompression (AD) during prolonged AHUP CPR, since AD can be difficult to perform manually for an extended period. Hypothesis: Full AD is needed to optimize hemodynamics during prolonged AHUP CPR Methods: Six female and male farm pigs (~40 kg) were sedated, intubated, anesthetized, and monitored. After 8 min of untreated ventricular fibrillation followed by ≥ 30 min of AHUP CPR with an automated device, AHUP CPR was continued except that AD was intentionally reduced from an average of 3.33 ± 0.37 cm of lift to 0 cm lift above the resting neutral position as this is the amount of decompression that occurs with C-CPR and passive chest wall recoil. After 1 min of AHUP CPR with 0 cm lift, AD was progressively increased back to 3 cm of lift over 3 min. Hemodynamics (mean ± SD) were compared using Student’s t test, where p&lt;0.05 was considered statistically significant. Results Coronary perfusion pressure (CorPP) (p&lt;0.005), cerebral perfusion pressure (CerPP) (p&lt;0.001), and ETCO2 (p&lt;0.0001) significantly decreased after AD was discontinued (Fig.1). With restoration of AD to 3 cm, CorPP (p&lt;0.009) and ETCO2 (p&lt;0.001) significantly improved and CerPP trended higher (p=0.084). Conclusion During prolonged (≥ 30 min) AHUP CPR in pigs, active lift of the chest wall is essential to maintain stable hemodynamics. Hemodynamics deteriorated rapidly with intentional loss of AD, but could be partially restored with resumption of AD.

Faster time to automated elevation of the head and thorax during cardiopulmonary resuscitation increases the probability of return of spontaneous circulation

ObjectivesResuscitation in the Head Up position improves outcomes in animals treated with active compression decompression cardiopulmonary resuscitation and an impedance threshold device (ACD + ITD CPR).We assessed impact of time to deployment of an automated Head Up position (AHUP) based bundle of care after out-of-hospital cardiac arrest on return of spontaneous circulation (ROSC). MethodsObservational data were analyzed from a patient registry. Patients received treatment with 1) ACD + and/or automated CPR 2) an ITD and 3) an AHUP device. Probability of ROSC (ROSCprob) from the 9-1-1 call to AHUP device placement was assessed with a restricted cubic spline model and linear regression. ResultsOf 11 sites, 6 recorded the interval from 9-1-1 to AHUP device (n = 227). ROSCprobfor all rhythms was 34%(77/227). Median age (range) was 66 years (19-101) and 68% men. TheROSCprobfor shockable rhythms was 47%(18/38). Minutes from 9-1-1 to AHUP device (median, range) varied between sites: 1) 6.4(4,15), 2) 8.0(5,19), 3) 9.9(4, 12), 4) 14.1(6, 36), 5) 15.9(6, 34), 6) 19.0(8, 38),(p = 0.0001).ROSCprobalso varied; 1) 55.1%(16/29), 2) 60%(3/5), 3) 50%(3/6), 4) 22.7%(17/75), 5) 26.4%(9/34), and 6) 37.1%(29/78), (p = 0.019). For all rhythms between 4 and 12 min (n = 85),ROSCprobdeclined 5.6% for every minute elapsed (p = 0.024). For shockable rhythms, between 6 and 15 min (n = 23),ROSCprobdeclined 9.0% for every minute elapsed (p = 0.006). ConclusionsFaster time to deployment of an AHUP based bundle of care is associated with higher incidence of ROSC. This must be considered when evaluating and implementing this bundle.

Mechanical active compression-decompression versus standard mechanical cardiopulmonary resuscitation: A randomised haemodynamic out-of-hospital cardiac arrest study

BackgroundActive compression-decompression cardiopulmonary resuscitation (ACD-CPR) utilises a suction cup to lift the chest-wall actively during the decompression phase (AD). We hypothesised that mechanical ACD-CPR (Intervention), with AD up to 30 mm above the sternal resting position, would generate better haemodynamic results than standard mechanical CPR (Control). MethodsThis out-of-hospital adult non-traumatic cardiac arrest trial was prospective, block-randomised and non-blinded. We included intubated patients with capnography recorded during mechanical CPR. Exclusion criteria were pregnancy, prisoners, and prior chest surgery. The primary endpoint was maximum tidal carbon dioxide partial pressure (pMTCO2) and secondary endpoints were oxygen saturation of cerebral tissue (SctO2), invasive arterial blood pressures and CPR-related injuries. Intervention device lifting force performance was categorised as Complete AD (≥30 Newtons) or Incomplete AD (≤10 Newtons). Haemodynamic data, analysed as one measurement for each parameter per ventilation (Observation Unit, OU) with non-linear regression statistics are reported as mean (standard deviation). A two-sided p-value < 0.05 was considered as statistically significant. ResultsOf 221 enrolled patients, 210 were deemed eligible (Control 109, Intervention 101). The Control vs. Intervention results showed no significant differences for pMTCO2: 29(17) vs 29(18) mmHg (p = 0.86), blood pressures during compressions: 111(45) vs. 101(68) mmHg (p = 0.93) and decompressions: 21(20) vs. 18(18) mmHg (p = 0.93) or for SctO2%: 55(36) vs. 57(9) (p = 0.42). The 48 patients who received Complete AD in > 50% of their OUs had higher SctO2 than Control patients: 58(11) vs. 55(36)% (p < 0.001). ConclusionsMechanical ACD-CPR provided similar haemodynamic results to standard mechanical CPR. The Intervention device did not consistently provide Complete AD. Clinical trial registrationClinicalTrials.gov identifier (NCT number): NCT02479152. The Haemodynamic Effects of Mechanical Standard and Active Chest Compression-decompression During Out-of-hospital CPR.

Mathematical model of modified hybrid pump mechanism for cardiopulmonary resuscitation

Background and objectiveThe “Cardiac pump theory” and “Thoracic pump theory” are representative theories of cardiopulmonary resuscitation (CPR) mechanisms. Based on these theories, many studies on mathematical modeling have been performed to help understand hemodynamics during CPR. However, there are parts that do not yet properly reflect the physiology of CPR. Therefore, this study aims to develop a lumped parameter model of CPR that can more accurately reflect the current CPR physiology. MethodsBy adding compartments of the superior and inferior vena cava of the thoracic cavity to the existing CPR model, and the “Hybrid pump” mechanism was applied to simulate CPR. To compare the hemodynamics of the conventional CPR model and the developed CPR model, various conditions, such as active compression–decompression CPR with an impedance threshold valve device (ACD–CPR+ITV), head-up-tilt (HUT), and head-down-tilt (HDT), were simulated. The coronary perfusion pressure (CPP) was compared by modulating the compression ratio of the atrium and ventricle with the thoracic pump factor. ResultsThe result for the comparison of coronary blood flow showed that the existing model is predominant in the compression phase, whereas the developed model is dominant in the relaxation phase. ACD–CPR + ITV results showed that the CPP decreased by 5 % in the existing model, and increased by about 46 % in the developed model, revealing a distinct hemodynamic difference between the two models. Likewise, as a result of comparing the hemodynamic differences of the two models according to the changes in tilt angle, the HUT showed similar trends, while the HDT showed slightly different results. The CPP varied accordingly with the ratio of the ventricular and atrial thoracic pump factor. ConclusionComparison of the hemodynamics with the existing model by simulating various conditions showed that the developed CPR model reflects the CPR physiology better. The model suggests that the hemodynamics may vary depending on the ventricle and atrium compression ratio. This study may provide an important basis for helping understand various situations and patient-specific hemodynamic characteristics during CPR through in-depth research, such as patient-specific model and parameter optimization.

Improving post-cardiac arrest cerebral perfusion pressure by elevating the head and thorax

AimThe optimal head and thorax position after return of spontaneous circulation (ROSC) following cardiac arrest (CA) is unknown. This study examined whether head and thorax elevation post-ROSC is beneficial, in a porcine model. MethodsProtocol A: 40 kg anesthetized pigs were positioned flat, after 7.75 min of untreated CA the heart and head were elevated 8 and 12 cm, respectively, above the horizontal plane, automated active compression decompression (ACD) plus impedance threshold device (ITD) CPR was started, and 2 min later the heart and head were elevated 10 and 22 cm, respectively, over 2 min to the highest head up position (HUP). After 30 min of CPR pigs were defibrillated and randomized 10 min later to four 5-min epochs of HUP or flat position. Multiple physiological parameters were measured. In Protocol B, after 6 min of untreated VF, pigs received 6 min of conventional CPR flat, and after ROSC were randomized HUP versus Flat as in Protocol A. The primary endpoint was cerebral perfusion pressure (CerPP). Multivariate analysis-of-variance (MANOVA) for repeated measures was used. Data were reported as mean ± SD. ResultsIn Protocol A, intracranial pressure (ICP) (mmHg) was significantly lower post-ROSC with HUP (9.1 ± 5.5) versus Flat (18.5 ± 5.1) (p < 0.001). Conversely, CerPP was higher with HUP (62.5 ± 19.9) versus Flat (53.2 ± 19.1) (p = 0.004), respectively. Protocol A and B results comparing HUP versus Flat were similar. ConclusionPost-ROSC head and thorax elevation in a porcine model of cardiac arrest resulted in higher CerPP and lower ICP values, regardless of VF duration or CPR method. IACUC Protocol Number19-09.

Abstract 344: Comparing the Efficacy of Real-Time Audiovisual Feedback Devices and Active Compression-Decompression Devices in Out-of-Hospital Cardiac Arrest: A Network Meta-Analysis

Introduction: Nearly 350,000 out-of-hospital cardiac arrest (OHCA) cases occur annually in the United States, with a fatality rate nearing 90%. Quality of cardiopulmonary resuscitation (CPR) is known to significantly influence survival. Randomized controlled trials (RCT) on real-time audiovisual feedback (RTAVF) and active compression-decompression (ACD) devices show both provide substantial advantages to standard CPR. We conducted the first network meta-analysis comparing the efficacy of RTAVF and ACD devices in OHCA based on a literature review. Methods: Studies examining the efficacy of RTAVF or ACD devices to standard CPR by emergency medical personnel in OHCA cases were identified in PubMed, SCOPUS, Cochrane, Google Scholar, and Embase. Outcomes of interest were return of spontaneous circulation (ROSC), survival to hospital discharge (SHD), and favorable neurological recovery. Both a frequentist and Bayesian network meta-analysis were conducted. The p-values, P-scores and Surface under the Cumulative Ranking (SUCRA) scores were computed to analyze significance and effect size. Results: The search yielded 31 eligible studies (n = 35,575). RTAVF devices significantly improved ROSC (Risk Ratio (RR) 1.15, 95% CI: 1.09 - 1.22, p &lt; 0.001, P-score &gt; 0.999) and SHD (RR 1.16, 1.07 - 1.26, p &lt; 0.001, P-score &gt; 0.91), but did not significantly improve favorable neurological recovery (RR 1.05, 0.92 - 1.19, p &gt; 0.05). ACD devices did not report significant improvement in either ROSC (RR 1.03, 0.99 - 1.08, p &gt; 0.05) or SHD (RR 1.10, 0.99 - 1.21, p &gt; 0.05), but did report significant benefits in favorable neurological outcome (RR 1.30, 1.07 - 1.58, p &lt; 0.01, P-score &gt; 0.97). Similar findings were also seen in SUCRA scores. Conclusion: We found RTAVF devices increased ROSC and SHD, while ACD devices increased favorable neurological recovery. Our meta-analysis supports the adoption of RTAVF devices, but an RCT directly comparing RTAVF with ACD devices is recommended.

Controlled sequential elevation of the head and thorax combined with active compression decompression cardiopulmonary resuscitation and an impedance threshold device improves neurological survival in a porcine model of cardiac arrest

Aim of the studyControlled sequential elevation of the head and thorax (CSE) during active compression decompression (ACD) cardiopulmonary resuscitation (CPR) with an impedance threshold device (ITD) has been shown to increase cerebral perfusion pressure and cerebral blood flow in previous animal studies as compared to the traditional supine position. The potential for this novel bundled treatment strategy to improve survival with intact neurological function is unknown. MethodsFemale farm pigs were sedated, intubated, and anesthetized. Central arterial and venous access were continuously monitored. Regional brain tissue perfusion (CerO2) was also measured transcutaneous. Ventricular fibrillation (VF) was induced and untreated for 10 min. Pigs were randomized to (1) Conventional CPR (C-CPR) flat or (2) ACD + ITD CSE CPR that included 2 min of ACD + ITD with the head and heart first elevated 10 and 8 cm, and then gradual elevation over 2 min to 22 and 9 cm, respectively. After 19 min of CPR, pigs were defibrillated and recovered. A veterinarian blinded to the intervention assessed cerebral performance category (CPC) at 24 h. A neurologically intact outcome was defined as a CPC score of 1 or 2. Categorical outcomes were analyzed by Fisher's exact test and continuous outcomes with an unpaired student's t-test. ResultsIn 16 animals, return of spontaneous circulation rate was 8/8 (100%) with ACD + ITD CSE and 3/8 (25%) for C-CPR (p = 0.026). For the primary outcome of neurologically intact survival, 6/8 (75%) pigs had a CPC score 1 or 2 with ACD + ITD CSE versus 1/8 (12.5%) with C-CPR (p = 0.04). Coronary perfusion pressure (mmHg, mean ± SD) was higher with CSE at 18 min (41 ± 24 versus 10 ± 5, p = 0.004). rSO2 (%, mean ± SD) and ETCO2 (mmHg, mean ± SD) values were higher at 18 min with CSE (32 ± 9 versus 17 ± 2, p = 0.01, and 55 mmHg ± 10 versus 21 mmHg ± 4, p < 0.001), respectively. ConclusionsThe novel bundled resuscitation approach of CSE with ACD + ITD CPR increased favorable neurological survival versus C-CPR in a swine model of cardiac arrest.

Elevation of head and thorax increases cerebral perfusion pressure and lowers intracranial pressure after restoration of spontaneous circulation in a porcine model of cardiac arrest

Aim: Pre-clinical studies have shown that a controlled sequential head and thorax elevation during active compression decompression (ACD) cardiopulmonary resuscitation (CPR) with an impedance threshold device (ITD) improves cerebral blood flow vs. the flat position. The optimal head and thorax position after return of spontaneous circulation (ROSC) is unknown. The aim of this study is to determine whether head and thorax elevation is beneficial post-ROSC.

Controlled progressive elevation rather than an optimal angle maximizes cerebral perfusion pressure during head up CPR in a swine model of cardiac arrest

Aim of the StudyElevation of the head and thorax (HUP) during cardiopulmonary resuscitation (CPR) has been shown to double brain blood flow with increased cerebral perfusion pressures (CerPP) after active compression-decompression (ACD) CPR with an impedance threshold device (ITD). However, the optimal angle for HUP CPR is unknown. MethodsIn Study A, different angles were assessed (20°, 30°, 40°), each randomized over 5-min periods of ACD + ITD CPR, after 8 min of untreated ventricular fibrillation in an anesthetized swine model. Based upon Study A, Study B was performed, where animals were randomized to 1 of 2 sequences: 20°, 30°, 40° or 40°, 30°, 20° with a similar protocol. The primary endpoint was CerPP for both studies. ResultsIn Study A, no optimal HUP angle was observed in 18 pigs. CerPPs for 30° and 40° (mmHg, mean ± SD) were equivalent (44 ± 22 and 47 ± 26, p = 0.18). However, CerPP appeared higher when 40° HUP was performed during the last 5-min of CPR, suggestive of a sequence effect. For Study B, after 17 min of CPR, CerPP (mmHg) were higher with the 20°, 30°, 40° sequence: 60 ± 17 versus 33 ± 18 (p = 0.035). ConclusionsNo optimal HUP CPR angle was observed. However, controlled progressive elevation of the head and thorax during CPR is more beneficial than an absolute angle or height to maximize CerPP. Further studies are needed to determine the optimal rate of rise during HUP ACD + ITD CPR. Institutional Protocol Number17-06.

Effect of controlled sequential elevation timing of the head and thorax during cardiopulmonary resuscitation on cerebral perfusion pressures in a porcine model of cardiac arrest

AimControlled sequential elevation of the head and thorax (CSE) during active compression–decompression (ACD) CPR with an impedance threshold device (ITD) augments cerebral (CerPP) and coronary (CorPP) perfusion pressures. The optimal CSE is unknown. MethodsAfter 8 minutes of untreated VF, 40 kg anesthetized female pigs were positioned on a customized head and thorax elevation device (CED). After 2 min of automated ACD + ITD-16 CPR to ‘prime the system’, 12 pigs were randomized to CSE to the highest CED position over 4-min or 10-min. The primary outcome was CerPP after 7 minutes of CPR. Secondarily, 24-sec (without a priming step) and 2-min CSE times were similarly tested (n = 6 group) in a non-randomized order. Values expressed as mean ± SD. ResultsAfter 7 min of CPR, CerPPs were significantly higher in the 4-min vs 10-min CSE groups (53 ± 14.4 vs 38.5 ± 3.6 mmHg respectively, p = 0.03) whereas CorPP trended higher. The 4-min CSE group achieved 50% of baseline (50% BL) CerPP faster than the 10-min group (2.5 ± 1.2 vs 6 ± 3.1 minutes, p = 0.03). CerPP values in the 2-min and 4-min CSE groups were significantly higher than in the 24-sec group. With CSE, CerPPs and CorPPs increased over time in all groups. ConclusionsBy optimizing controlled sequential elevation timing, CerPP values achieved 50% of baseline within less than 2.5 minutes and >80% of baseline after 7 minutes of CPR. This novel CPR approach rapidly restored CerPPs to near normal values non-invasively and without vasopressors.