The Physiology of Cardiopulmonary Resuscitation

Modeling and simulation of cardiovascular system under cardiac arrest for finding a more effective CPR technique

Cardio-Pulmonary Resuscitation (CPR) saves life. However, all the current CPR methods produce only one third to one quarter of the normal cardiac output and hence post-CPR survival has remained very poor. We report a better CPR technique exhibiting increased cardiac output as compared to existing techniques. Obviously, one cannot perform such studies on humans; therefore, we developed a fluidic model of the cardiovascular system under cardiac arrest. This enabled us to actuate different organs independently, sequentially and/or combinatorially to find the most effective CPR technique. Extensive simulations were performed using Simscape®. Our novel combination (combination-1) shows 10.75% improvement in peak aortic pressure and 8.3% improvement in peak cardiac flow-rate with 120 compressions per minute with respect to the baseline CPR method as per AHA/ERC guidelines. Similar improvements were observed at compression rates of 80 and 100 per minute. In addition to finding a more effective CPR technique, we also present our passive cardiovascular model as an open-source software package where different preconditions and modalities can be set prior to conducting the cardiovascular simulations. Thus, it may also serve as a simulator to explore the cardiovascular system behaviors as well as the effects of different contributing factors.

Intraventricular pressure and volume during conventional and automated head-up CPR

BACKGROUND

Active compression-decompression (ACD) CPR, an impedance threshold device (ITD) and automated head and thorax elevation, collectively termed AHUP-CPR, increases cerebral and coronary perfusion pressures, brain blood flow, end-tidal CO2 (ETCO2) and cerebral oximetry (rSO2) in animal models compared with conventional (C) CPR. We tested the hypothesis that cardiac stroke volume (SV) is higher with AHUP-CPR versus C-CPR or ACD + ITD in a porcine cardiac arrest model.

METHODS

Farm pigs (n = 14) were sedated, anesthetized, and ventilated. Hemodynamics, including biventricular pressure-volume loops, were continuously measured. Following 10 min of untreated ventricular fibrillation, C-CPR was performed for 2 min, then ACD + ITD for 2 min in the flat position, and then AHUP-CPR thereafter. Linear mixed-effects model and Pearson correlation comparisons were used for statistical analysis.

RESULTS

Coronary and cerebral perfusion pressures, ETCO2, rSO2, and right (RV) and left (LV) ventricular SV increased progressively and significantly with the implementation of AHUP-CPR (p < 0.05). RV SV with C-CPR was 24.8 ± 2.8 mL (∼48% of baseline) versus 45.2 ± 4.1 with AHUP-CPR (∼90% of baseline) (p < 0.01). LV SV with C-CPR was 17.6 ± 1.8 mL (∼35% of baseline) versus 38.7 ± 6.7 with AHUP-CPR (∼80% of baseline) (p < 0.01).

CONCLUSION

A fundamental and inherent shortcoming of C-CPR, limited cardiac stroke volume, and resultant forward flow, can be overcome with AHUP-CPR. These findings may help explain the better outcomes associated with early use of AHUP-CPR.

[VA-ECMO-assisted resuscitation for refractory cardiac arrest]

Extracorporeal cardiopulmonary resuscitation (ECPR) is an invasive medical intervention using mechanical circulatory support for treating cardiac arrest beyond the limits of conventional cardiopulmonary resuscitation (CCPR). ECPR uses veno-arterial extracorporeal membrane oxygenation (VA-ECMO) to maintain organ perfusion while treating reversible causes of cardiac arrest. Commonly applied criteria to select suitable patients include witnessed cardiac arrest, early bystander CPR, and a time frame of less than 60 minutes from collapse to ECPR initiation.A meta-analysis by Low et al. (2023), which included 11 studies with 4,595 ECPR and 4,597 CCPR patients, demonstrated that ECPR was not only associated with higher survival rates, but also better long-term neurological outcomes. Additionally, a higher number of ECPR procedures per center was linked to reduced mortality rates. A 2024 updated meta-analysis confirmed these findings and demonstrated further that ECPR significantly reduced in-hospital mortality in patients with out-of-hospital cardiac arrest (OHCA).Further insights on this topic can be gained from the individual studies on ECPR for treatment of OHCA: In general, there are several different modalities of how ECPR can be deployed, ranging from implantation at the site of the index event vs. implantation in the hospital, and even the place of implantation in the hospital varies. However, it seems that the actual pathway of how the VA-ECMO is implanted is of lower importance, and highly depends on the local infrastructure of a given hospital (rural area vs. municipal area), while achieving the lowest possible low-flow time should be the primary goal.The available data also shows that, despite all the advances, ECPR is still a high-risk intervention which is very demanding on the personnel and requires an abundance of resources.Overall, ECPR is a promising therapy for patients with OHCA to improve survival with good neurological outcome, but only if applied in a highly structured and standardized way, and in carefully selected patients.

Extracorporeal cardiopulmonary resuscitation outcomes in pre-Glenn single ventricle infants: Analysis of a ten-year dataset

BACKGROUND

While several studies have reported on outcomes of extracorporeal membrane oxygenation (ECMO) in patients with single ventricle physiology, few studies have described outcomes of extracorporeal cardiopulmonary resuscitation (ECPR) in this unique population. The objective of this study was to determine survival and risk factors for mortality after ECPR in single ventricle patients prior to superior cavopulmonary anastomosis, using a large sample from the Extracorporeal Life Support Organization (ELSO) Registry.

METHODS

We included single ventricle patients who underwent ECPR for in-hospital cardiac arrest (IHCA) between January 2012 and December 2021. We excluded patients who had undergone a superior cavopulmonary anastomosis, inferior cavopulmonary anastomosis, or who were older than 180 days at the time of ECPR. We collected data on mortality, ECMO course and ECMO complications. Subjects who survived to hospital discharge after ECPR were compared to subjects who did not survive to hospital discharge. We then performed univariate logistic regression followed by multivariable logistic regression analysis for associations with survival to hospital discharge.

RESULTS

There were 420 subjects included who had index ECPR events. Median age was 14 (IQR 7,44) days and median weight was 3.14 (IQR 2.8, 3.8) kg.. Hypoplastic left heart syndrome was the most common diagnosis (354/420; 84.2%), and 47.4% of the cohort (199/420) had undergone a Norwood operation. Survival to hospital discharge occurred in 159/420 (37.9%) of subjects. Median number of hours on ECMO (122 vs. 93 h; p < 0.001), presence of seizures by electroencephalography (24% vs. 15%; p = 0.033), and need for renal replacement therapy (45% vs. 34%; p = 0.023) were significantly higher among non-survivors compared to survivors. In the subgroup of Norwood patients, survival was 43.2% after ECPR. Presence of Norwood variable was 54% among ECPR survivors in the overall cohort, compared to 43% among non-survivors (p = 0.032). In a multivariable logistic regression model to test association with survival to discharge, number of ECMO hours and presence of seizures were associated with decreased odds of survival to hospital discharge [adjusted odds ratio 0.95 (95% C.I. 0.92-0.98) and 0.57 (95% C.I. 0.33-0.97) respectively]. The odds ratio for ECMO hours demonstrated a decrease in odds of survival by 5% for every 12 h on ECMO. Presence of Norwood operation pre-arrest was associated with increased odds of survival [adjusted odds ratio 1.53 (95% C.I. 1.01-2.32)].

CONCLUSION

In our cohort of pre-Glenn single ventricle infants, survival after ECPR for in-hospital cardiac arrest was 37.9%. Number of hours on ECMO and seizures post-ECMO cannulation were associated with decreased odds of survival. Single ventricle infants who had undergone Norwood palliation pre-arrest were more likely to survive to hospital discharge.

Impact of a Quality Cardiopulmonary Resuscitation Coach on Pediatric Intensive Care Unit Resuscitation Teams

BACKGROUND

The quality cardiopulmonary resuscitation (CPR) coach role was developed for hospital-based resuscitation teams. This supplementary team member (CPR coach) provides real-time, verbal feedback on chest compression quality to compressors during a cardiac arrest.

OBJECTIVES

To evaluate the impact of a quality CPR coach training intervention on resuscitation teams, including presence of coaches on teams and physiologic metrics of quality CPR delivery in real compression events.

METHODS

The quality CPR coach curriculum and role implementation were designed and evaluated using a logic model framework. Medical records of patients who had in-unit cardiopulmonary arrests were reviewed retrospectively. Data included physiologic metrics of quality CPR delivery. Analysis included descriptive statistics and comparison of arrest data before and after the intervention.

RESULTS

A total of 79 cardiopulmonary arrests were analyzed: 40 before and 39 after the intervention. Presence of a quality CPR coach on resuscitation teams was more frequent after training, increasing from 35% before the intervention to 72% after (P = .002). No significant difference was found in the frequency of application of Zoll defibrillator pads. Metrics of quality CPR delivery and adherence with American Heart Association recommendations were either unchanged or improved after the intervention.

CONCLUSIONS

The quality CPR coach training intervention significantly increased coach presence on code teams, which was associated with clinically significant improvements in some metrics of quality CPR delivery in real cardiopulmonary arrests.

2024 American Heart Association and American Academy of Pediatrics Focused Update on Special Circumstances: Resuscitation Following Drowning: An Update to the American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care

Drowning is the third leading cause of death from unintentional injury worldwide, accounting for 7% of all injury-related deaths. The World Health Organization estimates that there are ≈236 000 deaths due to drowning worldwide each year. Significant efforts have focused on creating systems to prevent drowning, but an average of 4000 fatal and 8000 nonfatal drownings still occur annually in the United States-likely an underestimate. Drowning generally progresses from initial respiratory arrest due to submersion-related hypoxia to cardiac arrest; thus, it can be challenging to distinguish respiratory arrest from cardiac arrest because pulses are difficult to accurately palpate within the recommended 10-second window. Therefore, resuscitation from cardiac arrest attributable to this specific circumstance must focus on restoring breathing as much as it does circulation. Resuscitation from drowning may begin with in-water rescue breathing when safely provided by rescuers trained in the technique and should continue with chest compressions, in keeping with basic life support guidelines, once the drowned individual and the rescuer are in a safe environment (eg, dry land, a boat). This focused update incorporates systematic reviews from 2021 to 2023 performed by the International Liaison Committee on Resuscitation related to the resuscitation of drowning. These clinical guidelines are the product of a committee of experts representing the American Heart Association and the American Academy of Pediatrics. The writing group reviewed the recent International Liaison Committee on Resuscitation systematic reviews, including updated literature searches, prior guidelines related to resuscitation from cardiac arrest following drowning, and other drowning-related publications from the American Heart Association and American Academy of Pediatrics. The writing group used these reviews to update its recommendations aimed at resuscitation of cardiac arrest following drowning in adults and children.

Comparison of end tidal CO2 levels between automated head up and conventional cardiopulmonary resuscitation: A pre-post intervention trial

BACKGROUND

The combination of controlled automated head/thorax elevation, active compression-decompression (ACD) cardiopulmonary resuscitation (CPR), and an impedance threshold device (ITD-16), termed AHUP-CPR, lowers intracranial pressure and increases circulation and neurologically-sound survival in pigs versus conventional (C) CPR. This study examined whether AHUP-CPR increased end tidal (ET) CO2, a non-invasive marker of cardiac output and organ perfusion, compared with C-CPR in witnessed out-of-hospital cardiac arrest patients.

METHOD

We conducted a prospective, single-arm, pre-post intervention trial in France between October 2019 and October 2022.Firefighters treated patients enrolled during the pre-intervention period with manual C-CPR and with AHUP-CPR during the post-intervention period. Advanced life support was provided by a physician-staffed 2nd-tier response vehicle for the two study periods. The primary outcome was the peak ETCO2 value measured during CPR.

RESULTS

122 patients with a mean age of 67 years (standard deviation [SD], 17) were enrolled (59 in the pre-intervention period and 63 in the post-intervention period). Based on an intention-to-treat analysis, mean baseline ETCO2 values were comparable between pre- (20.1 mmHg, SD,16.3) and post-(19.2 mmHg, SD, 16.3) intervention periods. Mean peak ETCO2 values during CPR were 30.3 mmHg (SD, 13.1) versus 40.7 mmHg (SD, 17.8) for the pre- and post-intervention study periods (mean difference, 10.6, 95% confidence interval, 4.6 to 16.1, P < 0.001). Mean differences in peak ETCO2 between study periods did not vary according to the first recorded cardiac rhythm (P for interaction = 0.99). The proportion of return of spontaneous circulation [19 (32.2%) vs. 21 (33.3%)], survival on hospital admission [17 (28.8%) vs. 19 (30.2%)], and 30-day survival with favorable neurological outcome [8 (13.6%) vs. 7 (11.1%)] did not differ between study periods.

CONCLUSION

ETCO2 values during AHUP-CPR reached the range of non-arrest normal physiological levels and were significantly higher than with C-CPR, regardless of the presenting cardiac rhythm.

Ventilation during cardiopulmonary resuscitation: A narrative review

Ventilation during cardiopulmonary resuscitation is vital to achieve optimal oxygenation but continues to be a subject of ongoing debate. This narrative review aims to provide an overview of various components and challenges of ventilation during cardiopulmonary resuscitation, highlighting key areas of uncertainty in the current understanding of ventilation management. It addresses the pulmonary pathophysiology during cardiac arrest, the importance of adequate alveolar ventilation, recommendations concerning the maintenance of airway patency, tidal volumes and ventilation rates in both synchronous and asynchronous ventilation. Additionally, it discusses ventilation adjuncts such as the impedance threshold device, the role of positive end-expiratory pressure ventilation, and passive oxygenation. Finally, this review offers directions for future research.

Automatic Mechanical Ventilation vs Manual Bag Ventilation During CPR: A Pilot Randomized Controlled Trial

BACKGROUND

There is insufficient evidence supporting the theory that mechanical ventilation can replace the manual ventilation method during CPR.

RESEARCH QUESTION

Is using automatic mechanical ventilation (MV) feasible and comparable to the manual ventilation method during CPR?

STUDY DESIGN AND METHODS

This pilot randomized controlled trial compared MV and manual bag ventilation (BV) during CPR after out-of-hospital cardiac arrest (OHCA). Patients with medical OHCA arriving at the ED were randomly assigned to two groups: an MV group using a mechanical ventilator and a BV group using a bag valve mask. Primary outcome was any return of spontaneous circulation (ROSC). Secondary outcomes were changes of arterial blood gas analysis results during CPR. Tidal volume, minute volume, and peak airway pressure were also analyzed.

RESULTS

A total of 60 patients were enrolled, and 30 patients were randomly assigned to each group. There were no statistically significant differences in basic characteristics of OHCA patients between the two groups. The rate of any return of spontaneous circulation was 56.7% in the MV group and 43.3% in the BV group, indicating no significant (P = .439) difference between the two groups. There were also no statistically significant differences in changes of PH, Pco2, Po2, bicarbonate, or lactate levels during CPR between the two groups (P values = .798, 0.249, .515, .876, and .878, respectively). Significantly lower tidal volume (P < .001) and minute volume (P = .009) were observed in the MV group.

INTERPRETATION

In this pilot trial, the use of MV instead of BV during CPR was feasible and could serve as a viable alternative. A multicenter randomized controlled trial is needed to create sufficient evidence for ventilation guidelines during CPR.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov; No.: NCT05550454; URL: www.

CLINICALTRIALS

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Interdisciplinary training program for pediatric cardiorespiratory arrest using rapid cycle deliberate practice: A descriptive cross-sectional study

BACKGROUND

cardiorespiratory arrest (CRA) is a severe public health concern, and clinical simulation has proven to be a beneficial educational strategy for training on this topic.

OBJECTIVE

To describe the implementation of a program for pediatric cardiac arrest care using rapid-cycle deliberate practice (RCDP), the quality of the technique employed, and participants' opinions on the methodology.

DESIGN AND SETTING

This descriptive cross-sectional study of pre- and post-performance training in cardiopul monary resuscitation (CPR) techniques and reaction evaluation was conducted in a hospital in São Paulo.

METHODS

Multidisciplinary groups performed pediatric resuscitation in a simulated scenario with RCDP mediated by a facilitator. The study sample included professionals working in patient care. During the simulation, the participants were evaluated for their compliance with the CRA care algorithm. Further, their execution of chest compressions was assessed pre- and post-intervention.

RESULTS

In total, 302 professionals were trained in this study. The overall quality of CPR measured pre-intervention was inadequate, and only 26% had adequate technique proficiency, whereas it was 91% (P < 0.01) post-intervention. Of the participants, 95.7% responded to the final evaluation and provided positive comments on the method and their satisfaction with the novel simulation. Of these, 88% considered that repetition of the technique used was more effective than traditional simulation.

CONCLUSIONS

The RCDP is effective for training multidisciplinary teams in pediatric CPR, with an emphasis on the quality of chest compressions. However, further studies are necessary to explore whether this trend translates to differential performances in practical settings.

Physiology-Guided Resuscitation: Monitoring and Augmenting Perfusion during Cardiopulmonary Arrest

Given the high morbidity and mortality associated with cardiopulmonary arrest, there have been multiple trials aimed at better monitoring and augmenting coronary, cerebral, and systemic perfusion. This article aims to elucidate these interventions, first by detailing the physiology of cardiopulmonary resuscitation and the available tools for managing cardiopulmonary arrest, followed by an in-depth examination of the newest advances in the monitoring and delivery of advanced cardiac life support.

Survival for Nonshockable Cardiac Arrests Treated With Noninvasive Circulatory Adjuncts and Head/Thorax Elevation

OBJECTIVES

Cardiac arrests remain a leading cause of death worldwide. Most patients have nonshockable electrocardiographic presentations (asystole/pulseless electrical activity). Despite well-performed basic and advanced cardiopulmonary resuscitation (CPR) interventions, patients with these presentations have always faced unlikely chances of survival. The primary objective was to determine if, in addition to conventional CPR (C-CPR), expeditious application of noninvasive circulation-enhancing adjuncts, and then gradual elevation of head and thorax, would be associated with higher likelihoods of survival following out-of-hospital cardiac arrest (OHCA) with nonshockable presentations.

DESIGN

Using a prospective observational study design (ClinicalTrials.gov NCT05588024), patient data from the national registry of emergency medical services (EMS) agencies deploying the CPR-enhancing adjuncts and automated head/thorax-up positioning (AHUP-CPR) were compared with counterpart reference control patient data derived from the two National Institutes of Health clinical trials that closely monitored quality CPR performance. Beyond unadjusted comparisons, propensity score matching and matching of time to EMS-initiated CPR (TCPR) were used to assemble cohorts with corresponding best-fit distributions of the well-established characteristics associated with OHCA outcomes.

SETTING

North American 9-1-1 EMS agencies.

PATIENTS

Adult nontraumatic OHCA patients receiving 9-1-1 responses.

INTERVENTIONS

In addition to C-CPR, study patients received the CPR adjuncts and AHUP (all U.S. Food and Drug Administration-cleared).

MEASUREMENTS AND MAIN RESULTS

The median TCPR for both AHUP-CPR and C-CPR groups was 8 minutes. Median time to AHUP initiation was 11 minutes. Combining all patients irrespective of lengthier response intervals, the collective unadjusted likelihood of AHUP-CPR group survival to hospital discharge was 7.4% (28/380) vs. 3.1% (58/1,852) for C-CPR (odds ratio [OR], 2.46 [95% CI, 1.55-3.92]) and, after propensity score matching, 7.6% (27/353) vs. 2.8% (10/353) (OR, 2.84 [95% CI, 1.35-5.96]). Faster AHUP-CPR application markedly amplified odds of survival and neurologically favorable survival.

CONCLUSIONS

These findings indicate that, compared with C-CPR, there are strong associations between rapid AHUP-CPR treatment and greater likelihood of patient survival, as well as survival with good neurological function, in cases of nonshockable OHCA.

Extracorporeal cardiopulmonary resuscitation for refractory cardiac arrest in Australia: a narrative review

Extracorporeal cardiopulmonary resuscitation (ECPR) in patients with prolonged or refractory out-of-hospital cardiac arrest (OHCA) is likely to be beneficial when used as part of a well developed emergency service system. ECPR is technically challenging to initiate and resource-intensive, but it has been found to be cost-effective in hospital-based ECPR programs. ECPR expansion within Australia has thus far been reactive and does not provide broad coverage or equity of access for patients. Newer delivery strategies that improve access to ECPR for patients with OHCA are being trialled, including networked hospital-based ECPR and pre-hospital ECPR programs. The efficacy, scalability, sustainability and cost-effectiveness of these programs need to be assessed. There is a need for national collaboration to determine the most cost-effective delivery strategies for ECPR provision along with its place in the OHCA survival chain.

Hemodynamics, survival and neurological function with early versus delayed automated head-up CPR in a porcine model of prolonged cardiac arrest

AIM

To determine if controlled head and thorax elevation, active compression-decompression cardiopulmonary resuscitation (CPR), and an impedance threshold device combined, termed automated head-up positioning CPR (AHUP-CPR), should be initiated early, as a basic (BLS) intervention, or later, as an advanced (ALS) intervention, in a severe porcine model of cardiac arrest.

METHODS

Yorkshire pigs (n = 22) weighing ∼40 kg were anesthetized and ventilated. After 15 minutes of untreated ventricular fibrillation, pigs were randomized to AHUP-CPR for 25 minutes (BLS group) or conventional CPR for 10 minutes, followed by 15 minutes of AHUP-CPR (ALS group). Thereafter, epinephrine, amiodarone, and defibrillation were administered. Neurologic function, the primary endpoint, was assessed 24-hours later with a Neurological Deficit Score (NDS, 0 = normal and 260 = worst deficit score or death). Secondary outcomes included return of spontaneous circulation (ROSC), cumulative survival, hemodynamics and epinephrine responsivity. Data, expressed as mean ± standard deviation, were compared using Fisher's Exact, log-rank, Mann-Whitney U and unpaired t-tests.

RESULTS

ROSC was achieved in 10/11 pigs with early AHUP-CPR versus 6/11 with delayed AHUP-CPR (p = 0.14), and cumulative 24-hour survival was 45.5% versus 9.1%, respectively (p < 0.02). The NDS was 203 ± 80 with early AHUP-CPR versus 259 ± 3 with delayed AHUP-CPR (p = 0.035). ETCO2, rSO2, and responsiveness to epinephrine were significantly higher in the early versus delayed AHUP-CPR.

CONCLUSION

When delivered early rather than late, AHUP-CPR resulted in significantly increased hemodynamics, 24-hour survival, and improved neurological function in pigs after prolonged cardiac arrest. Based on these findings, AHUP-CPR should be considered a BLS intervention.

Treatment of Refractory Cardiac Arrest by Controlled Reperfusion of the Whole Body: A Multicenter, Prospective Observational Study

Background: Survival following cardiac arrest (CA) remains poor after conventional cardiopulmonary resuscitation (CCPR) (6-26%), and the outcomes after extracorporeal cardiopulmonary resuscitation (ECPR) are often inconsistent. Poor survival is a consequence of CA, low-flow states during CCPR, multi-organ injury, insufficient monitoring, and delayed treatment of the causative condition. We developed a new strategy to address these issues. Methods: This all-comers, multicenter, prospective observational study (69 patients with in- and out-of-hospital CA (IHCA and OHCA) after prolonged refractory CCPR) focused on extracorporeal cardiopulmonary support, comprehensive monitoring, multi-organ repair, and the potential for out-of-hospital cannulation and treatment. Result: The overall survival rate at hospital discharge was 42.0%, and a favorable neurological outcome (CPC 1+2) at 90 days was achieved for 79.3% of survivors (CPC 1+2 survival 33%). IHCA survival was very favorable (51.7%), as was CPC 1+2 survival at 90 days (41%). Survival of OHCA patients was 35% and CPC 1+2 survival at 90 days was 28%. The subgroup of OHCA patients with pre-hospital cannulation showed a superior survival rate of 57.1%. Conclusions: This new strategy focusing on repairing damage to multiple organs appears to improve outcomes after CA, and these findings should provide a sound basis for further research in this area.

Continuous chest compressions are associated with higher peak inspiratory pressures when compared to 30:2 in an experimental cardiac arrest model

BACKGROUND

Ventilation during cardiopulmonary resuscitation (CPR) has long been a part of the standard treatment during cardiac arrests. Ventilation is usually given either during continuous chest compressions (CCC) or during a short pause after every 30 chest compressions (30:2). There is limited knowledge of how ventilation is delivered if it effects the hemodynamics and if it plays a role in the occurrence of lung injuries. The aim of this study was to compare ventilation parameters, hemodynamics, blood gases and lung injuries during experimental CPR given with CCC and 30:2 in a porcine model.

METHODS

Sixteen pigs weighing approximately 33 kg were randomized to either receive CPR with CCC or 30:2. Ventricular fibrillation was induced by passing an electrical current through the heart. CPR was started after 3 min and given for 20 min. Chest compressions were provided mechanically with a chest compression device and ventilations were delivered manually with a self-inflating bag and 12 l/min of oxygen. During the experiment, ventilation parameters and hemodynamics were sampled continuously, and arterial blood gases were taken every five minutes. After euthanasia and cessation of CPR, the lungs and heart were removed in block and visually examined followed by sampling of lung tissue which were examined using microscopy.

RESULTS

In the CCC group and the 30:2 group, peak inspiratory pressure (PIP) was 58.6 and 35.1 cmH2O (p < 0.001), minute volume (MV) 2189.6 and 1267.1 ml (p < 0.001), peak expired carbon dioxide (PECO2) 28.6 and 39.4 mmHg (p = 0.020), partial pressure of carbon dioxide (PaCO2) 50.2 and 61.1 mmHg (p = 0.013) and pH 7.3 and 7.2 (p = 0.029), respectively. Central venous pressure (CVP) decreased more over time in the 30:2 group (p = 0.023). All lungs were injured, but there were no differences between the groups.

CONCLUSIONS

Ventilation during CCC resulted in a higher PIP, MV and pH and lower PECO2 and PaCO2, showing that ventilation mode during CPR can affect ventilation parameters and blood gases.

Prone restraint death: Possible role of the Valsalva maneuver

There is an on-going debate about the safety of prone restraint and the exact role of the prone position in physical restraint death. Cardiac arrest in prone restraint death is essentially the end-result of a violent physical altercation wherein a combative individual suddenly loses consciousness while trying to counteract an opposing force. The direct correlations of increased static weight force with decreased inferior vena cava diameter, decreased cardiac output, and decreased stroke volume in prone restraint studies suggest that decreased venous return and decreased cardiac output could have a significant role to play in prone restraint death. Although the degree of changes observed in those studies might not be sufficient to cause cardiac arrest, they could predispose people who instinctively try to free themselves of the restraints to severe complications. The Valsalva maneuver, or forceful expiration against a closed airway, is frequently performed spontaneously in daily activities involving straining and resistance exercise, but has never been considered in restraint death. Pre-existing diminished venous return could increase the risk of major complications in individuals performing the Valsalva maneuver. A substantial decrease in venous return and cardiac output could increase the risk of cerebral hypoperfusion, loss of consciousness, hypoventilation, and sudden death. By increasing the risk of increased intra-abdominal pressure and its negative effect on venous return, high body mass index may be a significant risk factor in prone restraint death. The Valsalva maneuver may have different roles in prone restraint cardiac arrest and might be overlooked in prone restraint death.

The Minnesota first-responder AED project: Aiming to increase survival in out-of-hospital cardiac arrest

There are 350,000 out-of-hospital cardiac arrest (OHCA) cases annually in the United States of America. Using automated external defibrillators (AEDs) has increased survival in cardiac arrests (CA) with an initial shockable rhythm. Thus, guidelines recommend complete geographical coverage with AEDs. To fill in the gaps in Minnesota, the Center for Resuscitation Medicine at the University of Minnesota raised an $18.8 million grant from the Helmsley Charitable Trust to supply law enforcement first responders with AEDs and, thus, increase survival rates after OHCA by reducing the time to first shock. This report elaborates on the decision-making, fundraising, and logistic strategy required to reach statewide AED coverage.

Methods

The baseline need for AEDs was analyzed using a questionnaire sent out to state law enforcement agencies, state patrols, city and county agencies, and tribal agencies in 2021. Furthermore, OHCA cases of 2021 were reviewed. The combination of this information led to an action plan to equip and train all agencies throughout the state's eight regions with AEDs.

Results

The electronic survey was initially sent out to 358 agencies. The initial response rate was 77% (n = 276). This resulted in a total need of 8300 AEDs to be deployed over three years (2022-2025). As of 2023, over 4769 AEDs have been distributed, covering 237 sites.

Conclusion

By equipping first responders with AED systems, the Center for Resuscitation Medicine aims to shorten the gap in statewide AED coverage, thus increasing the chances of survival after OHCA.

Pre-Arrival Care of the Out-of-Hospital Cardiac Arrest Victim

Lay rescuers play a pivotal role in the recognition and initial management of out-of-hospital cardiac arrest. The provision of timely pre-arrival care by lay responders, including cardiopulmonary resuscitation and the use of automated external defibrillator before emergency medical service arrival, is important link in the chain of survival and has been shown to improve outcomes from cardiac arrest. Although physicians are not directly involved in bystander response to cardiac arrest, they play a key role in emphasizing the importance of bystander interventions.

Impact of a targeted temperature management quality improvement project on survival and neurologic outcomes in cardiac arrest patients

BACKGROUND

Targeted temperature management (TTM) is recommended for postresuscitation care of patients with sudden cardiac arrest (SCA) and its implementation remains challenging. This study aimed to evaluate the newly designed Quality Improvement Project (QIP) to improve the quality of TTM and outcomes of patients with SCA.

METHODS

Patients who experienced out-of-hospital cardiac arrest (OHCA) and in-hospital cardiac arrest (IHCA) with return of spontaneous circulation (ROSC) and were treated in our hospital between January 2017 and December 2019 were enrolled retrospectively. All included patients received QIP intervention initiated as follows: (1) Protocols and standard operating procedures were created for TTM; (2) shared decision-making was documented; (3) job training instruction was created; and 4) lean medical management was implemented.

RESULTS

Among 248 included patients, the postintervention group (n = 104) had shorter duration of ROSC to TTM than the preintervention group (n = 144) (356 vs 540 minutes, p = 0.042); better survival rate (39.4% vs 27.1%, p = 0.04), and neurologic performance (25.0% vs 17.4%, p < 0.001). After propensity score matching (PSM), patients who received TTM (n = 48 ) had better neurologic performance than those without TTM (n = 48) (25.1% vs 18.8%, p < 0.001). OHCA (odds ratio [OR] = 2.705, 95% CI: 1.657-4.416), age >60 (OR = 2.154, 95% CI: 1.428-3.244), female (OR = 1.404, 95% CI: 1.005-1.962), and diabetes mellitus (OR = 1.429, 95% CI: 1.019-2.005) were negative predictors of survival; while TTM (OR = 0.431, 95% CI: 0.266-0.699) and bystander cardiopulmonary resuscitation (CPR) (OR=0.589, 95% CI: 0.35-0.99) were positive predictors. Age >60 (OR= 2.292, 95% CI: 1.58-3.323) and OHCA (OR= 2.928, 95% CI: 1.858-4.616) were negative predictors of favorable neurologic outcomes; while bystander CPR (OR=0.572, 95% CI: 0.355-0.922) and TTM (OR=0.457, 95% CI: 0.296-0.705) were positive predictors.

CONCLUSION

A new QIP with defined protocols, documented shared decision-making, and medical management guidelines improves TTM execution, duration from ROSC to TTM , survival, and neurologic outcomes of cardiac arrest patients.

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) device and 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 device is 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.

Impact of intravenous fluid administration on cardiac output and oxygenation during cardiopulmonary resuscitation

BACKGROUND

The effect of intravenous fluid (IVF) administration during cardiopulmonary resuscitation (CPR) is an unexplored factor that may improve cardiac output (CO) during CPR. The aim of this study was to determine the effect of IVF administration on CO and oxygenation during CPR.

METHODS

This experimental animal study was performed in a critical care animal laboratory. Twenty-two Landrace-Yorkshire female piglets weighing 27-37 kg were anesthetized, intubated, and placed on positive pressure ventilation. Irreversible cardiac arrest was induced with bupivacaine. CPR was performed with a LUCAS 3 mechanical compression device. Pigs were randomized into IVF or no-IVF groups. Pigs in the IVF group were given 20 mL/kg of Plasma-Lyte (Baxter International, Deerfield, IL USA), infused from 15 to 35 min of CPR. CPR was maintained for 50 min with serial measurements of CO obtained using ultrasound dilution technology and partial pressure of oxygen (PaO₂).

RESULTS

A mixed-effects repeated measures analysis of variance was used to compare within-group, and between-group mean changes in CO and PaO₂ over time. CO and PaO₂ for the piglets were measured at 10-min intervals during the 50 min of CPR. CO was greater in the IVF compared with the control group at all time points during and after the infusion of the IVF. Mean PaO₂ decreased with time; however, at no time was there a significant difference in PaO₂ between the IVF and control groups.

CONCLUSIONS

Administration of IVF during CPR resulted in a significant increase in CO during CPR both during and after the IVF infusion. There was no statistically significant decrease in PaO₂ between the IVF and control groups.

Survival after multiple episodes of cardiac arrest

BACKGROUND

Cardiopulmonary resuscitation (CPR) is widely used in response to cardiac arrest. However, little is known regarding outcomes for those who undergo multiple episodes of cardiac arrest while in the hospital.

OBJECTIVES

The purpose of this study was to evaluate the association of multiple cardiac events with in-hospital mortality for patients admitted to our tertiary care hospital who underwent multiple code events.

METHODS

We performed a retrospective cohort study on all patients who underwent cardiac arrest from 2012 to 2016. Primary outcome was survival to discharge. Secondary outcomes included post-cardiac-arrest neurologic events (PCANE), non-home discharge, and one-year mortality.

RESULTS

There were 622 patients with an overall mortality rate of 78.0%. Patients undergoing CPR for cardiac arrest once during their admission had lower in-hospital mortality rates compared to those that had multiple (68.9% versus 91.3%, p<.01). Subset analysis of those who had multiple episodes of CPR revealed that more than one event within a 24-hour period led to significantly higher in-hospital mortality rates (94.7% versus 74.4%, p<.01). Other variables associated with in-hospital mortality included body mass index, female sex, malignancy, and increased down time per code. Patients that had a non-home discharge were more likely to have sustained a PCANE than those that were discharged home (31.4% versus 3.9%, p<.01). A non-home discharge was associated with higher one-year mortality rates compared to a home discharge (78.4% versus 54.3%, p=.01).

CONCLUSION

Multiple codes within a 24-hour period and the average time per code were associated with in-hospital mortality in cardiac arrest patients.

Clinical outcomes following out-of-hospital cardiac arrest: The minute-by-minute impact of bystander cardiopulmonary resuscitation

AIMS

The time-dependent prognostic role of bystander cardiopulmonary resuscitation (CPR) for out-of-hospital cardiac arrest (OHCA) patients has not been described with great precision, especially for neurologic outcomes. Our objective was to assess the association between bystander CPR, emergency medical service (EMS) response time, and OHCA patients' outcomes.

METHODS

This cohort study used the Resuscitation Outcomes Consortium Cardiac Epidemiologic Registries. Bystander-witnessed adult OHCA treated by EMS were included. The primary outcome was survival to hospital discharge and secondary outcome was survival with a good neurologic outcome (modified Rankin scale 0-2). Multivariable logistic regression models were used to assess the associations and interactions between bystander CPR, EMS response time and clinical outcomes.

RESULTS

Out of 229,637 patients, 41,012 were included (18,867 [46.0%] without bystander CPR and 22,145 [54.0%] with bystander CPR). Bystander CPR was independently associated with higher survival (adjusted odds ratio [AOR] = 1.70 [95%CI 1.61-1.80]) and survival with a good neurologic outcome (AOR = 1.87 [95%CI 1.70-2.06]), while longer EMS response times were independently associated with lower survival to hospital discharge (each additional minute of EMS response time: AOR = 0.92 [95%CI 0.91-0.93], p < 0.001) and lower survival with a good neurologic outcome (AOR = 0.88 [95%CI 0.86-0.89], p < 0.001). There was no interaction between bystander CPR and EMS response time's association with survival (p = 0.12) and neurologic outcomes (p = 0.65).

CONCLUSIONS

Although bystander CPR is associated with an immediate increase in odds of survival and of good neurologic outcome for OHCA patients, it does not influence the negative association between longer EMS response time and survival and good neurologic outcome.

Mechanical ventilation during cardiopulmonary resuscitation: influence of positive end-expiratory pressure and head-torso elevation

BACKGROUND

Efficient ventilation is important during cardiopulmonary resuscitation (CPR). Nevertheless, there is insufficient knowledge on how the patient's position affects ventilatory parameters during mechanically assisted CPR. We studied ventilatory parameters at different positive end-expiratory pressure (PEEP) levels and when using an inspiratory impedance valve (ITD) during horizontal and head-up CPR (HUP-CPR).

METHODS

In this human cadaver experimental study, we measured tidal volume (V_T) and pressure during CPR at different randomized PEEP levels (0, 5 or 10 cmH₂O) or with an ITD. CPR was performed, in the following order: horizontal (FLAT), at 18° and then at 35° head-thorax elevation. During the inspiratory phase we measured the net tidal volume (V_T) adjusted to predicted body weight (V_TPBW), reversed airflow (RAF), and maximum and minimum airway pressure (P_max and P_min).

RESULTS

Using ten thawed fresh-frozen cadavers we analyzed the inspiratory phase of 1843 respiratory cycles, 229 without CPR and 1614 with CPR. In a mixed linear model, thoracic position and PEEP significantly impacted V_TPBW (p < 0.001 for each), and the insufflation time, thoracic position and PEEP significantly affected the RAF (p < 0.001 for each) and P_max (p < 0.001). For P_min, only PEEP was significant (p < 0.001). In subgroup analysis, at 35° V_TPBW and P_max were significantly reduced compared with the flat or 18° position.

CONCLUSION

When using mechanical ventilation during CPR, it seems that the PEEP level and patient position are important determinants of respiratory parameters. Moreover, tidal volume seems to be lower when the thorax is positioned at 35°.

Influence of Basic Life Support on Donor Organs in Uncontrolled Donors After Cardiac Death

BACKGROUND

The aim of this study was to determine whether the application of basic life support (BLS) in patients who have experienced cardiac arrest and are subsequently referred to as uncontrolled asystole donors has any influence on the achievement of organs for subsequent transplantation.

METHODS

Demographic data, BLS, cause of death, emergency response times, and organ donations were collected. The analysis of quantitative variables following normal distribution is shown as mean (SD), and Student t distribution was used for comparison purposes. The analysis of variables that did not follow the normal distribution is shown as median (IQR), and Wilcoxon test was applied for comparison purposes.

RESULTS

A total of 91 cases of possible uncontrolled donor transfers were analyzed. Basic life support was provided to 61 patients (67.7%), whereas no BLS was provided to 27 patients (23.3%). Of the group that received BLS, 39 (73.6%) were effective donors compared with the non-BLS group, in which 22 (62.9%) were effective donors (P = .28).

CONCLUSIONS

We did not find an association between performing BLS compared with non-BLS and organ donation.

A prospective observational study on impact of epinephrine administration route on acute myocardial infarction patients with cardiac arrest in the catheterization laboratory (iCPR study)

BACKGROUND

Epinephrine is routinely utilized in cardiac arrest; however, it is unclear if the route of administration affects outcomes in acute myocardial infarction patients with cardiac arrest.

OBJECTIVES

To compare the efficacy of epinephrine administered via the peripheral intravenous (IV), central IV, and intracoronary (IC) routes.

METHODS

Prospective two-center pilot cohort study of acute myocardial infarction patients who suffered cardiac arrest in the cardiac catheterization laboratory during percutaneous coronary intervention. We compared the outcomes of patients who received epinephrine via peripheral IV, central IV, or IC.

RESULTS

158 participants were enrolled, 48 (30.4%), 50 (31.6%), and 60 (38.0%) in the central IV, IC, and peripheral IV arms, respectively. Peripheral IV epinephrine administration route was associated with lower odds of achieving return of spontaneous circulation (ROSC, odds ratio = 0.14, 95% confidence interval = 0.05-0.36, p < 0.0001) compared with central IV and IC administration. (There was no difference between central IV and IC routes; p = 0.9343.) The odds of stent thrombosis were significantly higher with the IC route (IC vs. peripheral IV OR = 4.6, 95% CI = 1.5-14.3, p = 0.0094; IC vs. central IV OR = 6.0, 95% CI = 1.9-19.2, p = 0.0025). Post-ROSC neurologic outcomes were better for central IV and IC routes when compared with peripheral IV.

CONCLUSION

Epinephrine administration via central IV and IC routes was associated with a higher rate of ROSC and better neurologic outcomes compared with peripheral IV administration. IC administration was associated with a higher risk of stent thrombosis. Trial registration This trial is registered at NCT05253937 .

Effectiveness of CPR in Hypogravity Conditions-A Systematic Review

(1) Background: Cardiopulmonary resuscitation (CPR), as a form of basic life support, is critical for maintaining cardiac and cerebral perfusion during cardiac arrest, a medical condition with high expected mortality. Current guidelines emphasize the importance of rapid recognition and prompt initiation of high-quality CPR, including appropriate cardiac compression depth and rate. As space agencies plan missions to the Moon or even to explore Mars, the duration of missions will increase and with it the chance of life-threatening conditions requiring CPR. The objective of this review was to examine the effectiveness and feasibility of chest compressions as part of CPR following current terrestrial guidelines under hypogravity conditions such as those encountered on planetary or lunar surfaces; (2) Methods: A systematic literature search was conducted by two independent reviewers (PubMed, Cochrane Register of Controlled Trials, ResearchGate, National Aeronautics and Space Administration (NASA)). Only controlled trials conducting CPR following guidelines from 2010 and after with advised compression depths of 50 mm and above were included; (3) Results: Four different publications were identified. All studies examined CPR feasibility in 0.38 G simulating the gravitational force on Mars. Two studies also simulated hypogravity on the Moon with a force of 0.17 G/0,16 G. All CPR protocols consisted of chest compressions only without ventilation. A compression rate above 100/s could be maintained in all studies and hypogravity conditions. Two studies showed a significant reduction of compression depth in 0.38 G (-7.2 mm/-8.71 mm) and 0.17 G (-12.6 mm/-9.85 mm), respectively, with nearly similar heart rates, compared to 1 G conditions. In the other two studies, participants with higher body weight could maintain a nearly adequate mean depth while effort measured by heart rate (+23/+13.85 bpm) and VO_2max (+5.4 mL·kg^-1·min^-1) increased significantly; (4) Conclusions: Adequate CPR quality in hypogravity can only be achieved under increased physical stress to compensate for functional weight loss. Without this extra effort, the depth of compression quickly falls below the guideline level, especially for light-weight rescuers. This means faster fatigue during resuscitation and the need for more frequent changes of the resuscitator than advised in terrestrial guidelines. Alternative techniques in the straddling position should be further investigated in hypogravity.

Extracorporeal cardiopulmonary resuscitation in adults and children: A review of literature, published guidelines and pediatric single-center program building experience

Extracorporeal cardiopulmonary resuscitation (ECPR) is an adjunct supportive therapy to conventional cardiopulmonary resuscitation (CCPR) employing veno-arterial extracorporeal membrane oxygenation (VA-ECMO) in the setting of refractory cardiac arrest. Its use has seen a significant increase in the past decade, providing hope for good functional recovery to patients with cardiac arrest refractory to conventional resuscitation maneuvers. This review paper aims to summarize key findings from the ECPR literature available to date as well as the recommendations for ECPR set forth by leading national and international resuscitation societies. Additionally, we describe the successful pediatric ECPR program at Texas Children's Hospital, highlighting the logistical, technical and educational features of the program.

Characterization of cerebral blood flow during open cardiac massage in swine: Effect of volume status

Introduction: Patients in cardiac arrest treated with resuscitative thoracotomy and open cardiac massage (OCM) have high rates of mortality with poor neurological outcomes. The aim of this study is to quantitate cerebral perfusion during OCM using computed tomography perfusion (CTP) imaging in a swine model of normo- and hypovolemia.

Methods: Anesthetized swine underwent instrumentation with right atrial and aortic pressure catheters. A catheter placed in the ascending aorta was used to administer iodinated contrast and CTP imaging acquired. Cerebral blood flow (CBF; ml/100 g of brain) and time to peak (TTP; s) were measured. Animals were then euthanized by exsanguination (hypovolemic group) or potassium chloride injection (normovolemic group) and subjected to a clamshell thoracotomy, aortic cross clamping, OCM, and repeated CTP. Data pertaining to peak coronary perfusion pressure (pCoPP; mmHg) were collected and % CoPP > 15 mmHg (% CoPP; s) calculated post hoc.

Results: Normovolemic animals (n = 5) achieved superior pCoPP compared to the hypovolemic animals (n = 5) pCoPP (39.3 vs. 12.3, p < 0.001) and % CoPP (14.5 ± 1.9 vs. 30.9 ± 6.5, p < 0.001). CTP acquisition was successful and TTP elongated from spontaneous circulation, normovolemia to hypovolemia (5.7 vs. 10.8 vs. 14.8, p = 0.01). CBF during OCM was similar between hypovolemic and normovolemic groups (7.5 ± 8.1 vs. 4.9 ± 6.0, p = 0.73) which was significantly lower than baseline values (51.9 ± 12.1, p < 0.001).

Conclusion: OCM in normovolemia generates superior coronary hemodynamics compared to hypovolemia. Despite this, neither generates adequate CBF as measured by CTP, compared to baseline. To improve the rate of neurologically intact survivors, novel resuscitative techniques need to be investigated that specifically target cerebral perfusion as existing techniques are inadequate.

The difference between arterial pCO2 and etCO2 after cardiac arrest - Outcome predictor or marker of unfavorable resuscitation circumstances?

INTRODUCTION

In former studies, the arterio-alveolar carbon dioxide gradient (ΔCO₂) predicted in-hospital mortality after initially survived cardiac arrest. As early outcome predictors are urgently needed, we evaluated ΔCO₂ as predictor for good neurological outcome in our cohort.

METHODS

We retrospectively analyzed all patients ≥18 years of age after non-traumatic in- and out of hospital cardiac arrest in the year 2018 from our resuscitation database. Patients without advanced airway management, incomplete datasets or without return of spontaneous circulation were excluded. The first arterial pCO₂ after admission and the etCO₂ in mmHg at the time of blood sampling were recorded from patient's charts. We then calculated ΔCO₂ (pCO₂ - etCO₂). For baseline analyses, ΔCO₂ was dichotomized into a low and high group with separation at the median. Good neurological outcome on day 30, expressed as Cerebral Performance Category 1-2, defined our primary endpoint. Survival to 30 days was used as secondary endpoint.

RESULTS

Out of 302 screened patients, 128 remained eligible for analyses. ΔCO₂ was lower in 30-day survivors with good neurological outcome (12.2 mmHg vs. 18.8 mmHg, p = 0.009) and in 30-day survivors (12.5 mmHg vs. 20.0 mmHg, p = 0.001). In patients with high ΔCO₂, a cardiac etiology of arrest was found less often. They had a higher body mass index, longer duration of resuscitation, higher amounts of epinephrine, lower pO₂ levels but both higher pCO2 and blood lactate levels, resulting in lower blood pH and HCO₃^- levels at admission. In a crude binary logistic regression analysis, ΔCO₂ was associated with 30-day neurological outcome (OR = 1.041 per mmHg of ΔCO₂, 95% CI 1.008-1.074, p = 0.014). This association persisted after the adjustment for age, sex, witnessed arrest and shockable first rhythm. However, after addition of the duration of resuscitation or the cumulative epinephrine dosage to the model, ΔCO₂ lost its association.

CONCLUSION

ΔCO₂ at admission after a successfully resuscitated cardiac arrest is associated with 30 days survival with good neurological outcome. However, a higher ΔCO₂ may rather be a surrogate for unfavorable resuscitation circumstances than an independent outcome predictor.

The immunology of the post-cardiac arrest syndrome

Patients successfully resuscitated from cardiac arrest often have brain injury, myocardial dysfunction, and systemic ischemia-reperfusion injury, collectively termed the post-cardiac arrest syndrome (PCAS). To improve outcomes, potential therapies must be able to be administered early in the post-arrest course and provide broad cytoprotection, as ischemia-reperfusion injury affects all organ systems. Our understanding of the immune system contributions to the PCAS has expanded, with animal models detailing biologically plausible mechanisms of secondary injury, the protective effects of available immunomodulatory drugs, and how immune dysregulation underlies infection susceptibility after arrest. In this narrative review, we discuss the dysregulated immune response in PCAS, human trials of targeted immunomodulation therapies, and future directions for immunomodulation following cardiac arrest.

Evaluation of abdominal compression-decompression combined with chest compression CPR performed by a new device: Is the prognosis improved after this combination CPR technique?

INTRODUCTION

This study was designed to compare the outcomes of standard cardiopulmonary resuscitation (STD-CPR) and combined chest compression and abdominal compression-decompression cardiopulmonary resuscitation (CO-CPR) with a new device following out-of-hospital cardiac arrest (OHCA). Moreover, we investigated whether patient prognosis improved with this combination treatment.

METHODS

This trial was a single-centre, prospective, randomized trial, and a blinded assessment of the outcomes was performed. A total of 297 consecutive patients with OHCA were initially screened, and 278 were randomized to the STD-CPR group (n = 135) or the CO-CPR group (n = 143). We compared the proportions of patients who achieved a return of spontaneous circulation (ROSC), survived to hospital admission and survived to hospital discharge. In addition, we also performed the Kaplan-Meier analysis with a log-rank test at the end of the follow-up period to compare the survival curves of the two groups.

RESULTS

The differences were not statistically significant in the proportion of patients who achieved ROSC [31/135 (23.0%) versus 35/143 (24.5%)] and survived to hospital admission [28/135 (20.7%) versus 33/143 (23.1%)] between the CO-CPR group and STD-CPR group. However, there was a significant difference in the proportion of patients who survived to hospital discharge [16/135 (11.9%) versus 7/143 (4.9%)] between the two groups. Nine patients (6.7%) in the CO-CPR group and 2 patients (1.4%) in the STD group showed good neurological outcomes according to the cerebral performance category (CPC) scale score, and the difference was statistically significant (P = 0.003). The Kaplan-Meier curves showed that the patients in the CO-CPR group achieved better survival benefits than those in the STD-CPR group at the end of the follow-up period (log-rank P = 0.007).

CONCLUSION

CO-CPR was more beneficial than STD-CPR in terms of survival benefits in patients who have suffered out-of-hospital cardiac arrest. Trial registration Chinese Clinical Trial Registry, registered number: ChiCTR2100049581 . Registered 30 July 2021- Retrospectively registered. http://www.medresman.org.cn/uc/index.aspx .

Standard CPR versus interposed abdominal compression CPR in shunted single ventricle patients: comparison using a lumped parameter mathematical model

INTRODUCTION

Cardiopulmonary resuscitation (CPR) in the shunted single-ventricle population is associated with poor outcomes. Interposed abdominal compression-cardiopulmonary resuscitation, or IAC-CPR, is an adjunct to standard CPR in which pressure is applied to the abdomen during the recoil phase of chest compressions.

METHODS

A lumped parameter model that represents heart chambers and blood vessels as resistors and capacitors was used to simulate blood flow in both Blalock-Taussig-Thomas and Sano circulations. For standard CPR, a prescribed external pressure waveform was applied to the heart chambers and great vessels to simulate chest compressions. IAC-CPR was modelled by adding phasic compression pressure to the abdominal aorta. Differential equations for the model were solved by a Runge-Kutta method.

RESULTS

In the Blalock-Taussig-Thomas model, mean pulmonary blood flow during IAC-CPR was 30% higher than during standard CPR; cardiac output increased 21%, diastolic blood pressure 16%, systolic blood pressure 8%, coronary perfusion pressure 17%, and coronary blood flow 17%. In the Sano model, pulmonary blood flow during IAC-CPR increased 150%, whereas cardiac output was improved by 13%, diastolic blood pressure 18%, systolic blood pressure 8%, coronary perfusion pressure 15%, and coronary blood flow 14%.

CONCLUSIONS

In this model, IAC-CPR confers significant advantage over standard CPR with respect to pulmonary blood flow, cardiac output, blood pressure, coronary perfusion pressure, and coronary blood flow. These results support the notion that single-ventricle paediatric patients may benefit from adjunctive resuscitation techniques, and underscores the need for an in-vivo trial of IAC-CPR in children.

Efficacy of heads-up CPR compared to supine CPR positions: Systematic review and meta-analysis

Background and Aim

Cardiopulmonary resuscitation (CPR) in full-coded patients requires effective chest compressions with minimal interruptions to maintain adequate perfusion to the brain and other vital organs. Many novel approaches have been proposed to attain better organ perfusion compared to traditional CPR techniques. The purpose of this review is to investigate the safety and efficacy of heads-up CPR versus supine CPR.

Methods

We searched PubMed Central, SCOPUS, Web of Science, and Cochrane databases from 1990 to February 2021. After the full-text screening of 40 eligible studies, only seven studies were eligible for our meta-analysis. We used the RevMan software (5.4) to perform the meta-analysis.

Results

In survival outcome, the pooled analysis between heads-up and supine CPR was (risk ratio = 0.98, 95% confidence interval [CI] = 0.17-5.68, p = 0.98). The pooled analyses between heads-up CPR and supine CPR in cerebral flow, cerebral perfusion pressure and coronary perfusion pressure outcomes, were (mean difference [MD] = 0.10, 95% CI = 0.03-0.17, p = 0.003), (MD = 12.28, 95% CI = 5.92-18.64], p = 0.0002), and (MD = 8.43, 95% CI = 2.71-14.14, p = 0.004), respectively. After doing a subgroup analysis, cerebral perfusion was found to increase during heads-up CPR compared with supine CPR at 6 min CPR duration and 18 to 20 min CPR duration as well.

Conclusion

Our study suggests that heads-up CPR is associated with better cerebral and coronary perfusion compared to the conventional supine technique in pigs' models. However, more research is warranted to investigate the safety and efficacy of the heads-up technique on human beings and to determine the best angle for optimization of the technique results.

Optimal Landmark for Chest Compressions during Cardiopulmonary Resuscitation Derived from a Chest Computed Tomography in Arms-Down Position

Compressions at the left ventricle increase rate of return of spontaneous circulation. This study aimed to identify the landmark of the point of maximal left ventricular diameter on the sternum (LVmax) by using chest computed tomography (CCT) in the arms-down position, which was similar to an actual cardiac arrest patient. A retrospective study was conducted between September 2014 and November 2020. We included adult patients who underwent CCT in an arms-down position and measured the rescuer’s hand. We measured the distance from the sternal notch to LVmax (DLVmax), to the lower half of sternum (DLH), and to the point of maximal force of hand, which placed the lowest palmar margin of the rescuer’s reference hand at the xiphisternal junction. Thirty-nine patients were included. The LVmax was located below the lower half of the sternum; DLVmax and DLH were 12.6 and 10.0 cm, respectively (p < 0.001). Distance from the sternal notch to the point of maximal force of the left hand, with the ulnar border located at the xiphisternal junction, was close to DLVmax; 11.3 and 12.6 cm, respectively (p = 0.076). In conclusion, LVmax was located below the lower half of the sternum, which is recommended by current guidelines.

Extracorporeal Life-Support For Out-Of-Hospital Cardiac Arrest: A Nationwide Multicenter Study

BACKGROUND

Despite potential clinical roles of extracorporeal life support (ECLS) for out-of-hospital cardiac arrest (OHCA) compared to that of conventional cardiopulmonary resuscitation (CCPR), use of ECLS for OHCA is not strongly endorsed by current clinical guidelines.

OBJECTIVE

The purpose of this study is to investigate the clinical roles of extracorporeal life support (ECLS) compared with that of conventional cardiopulmonary resuscitation (CCPR) for out-of-hospital cardiac arrest (OHCA) patients.

METHODS

The outcomes of OHCA between 2015 and 2020, enrolled in the Korean Cardiac Arrest Research Consortium (KoCARC), a multicenter OHCA patient registry including 65 participating hospitals throughout the Republic of Korea (ClinicalTrials.gov, number NCT03222999). Differences in clinical features were adjusted by matching the propensity for ECLS. The primary outcome was 30-day neurologically favorable survival with cerebral performance category of 1 or 2. Restricted mean survival time (RMST) was used to compare outcomes between groups.

RESULTS

Of 12,006 patients included, ECLS was applied to 272 patients (2.2%). The frequency of neurologically favorable survival was higher in the ECLS group than the CCPR group (RMST difference, 5.5 days [95% CI, 4.1-7.0 days], p < 0.001). In propensity score-matched 271 pairs, the clinical outcome of ECLS and CCPR did not differ to a statistically significant extent (RMST difference, 0.4 days [95% CI -1.6-2.5 days], p = 0.67). Subgroup analyses revealed that the clinical roles of ECLS was evident in patients with non-shockable rhythm or CPR time≥20 min (RMST difference, 2.7 days [95% CI 0.5-4.8 days], p = 0.015), but not in patients without these features (RMST difference, -3.7days [95% CI -7.6-0.2 days], p = 0.07).

CONCLUSIONS

In this real-world data analysis, ECLS compared to CCPR did not result in better overall clinical outcomes of OHCA. The clinical efficacy of ECLS may be limited to a subgroup of high-risk patients.

Carbon monoxide-releasing molecule-2 protects intestinal mucosal barrier function by reducing epithelial tight-junction damage in rats undergoing cardiopulmonary resuscitation

Background

Ischemia-reperfusion injury (IRI) to the small intestine is associated with the development of systemic inflammation and multiple organ failure after cardiopulmonary resuscitation (CPR). It has been reported that exogenous carbon monoxide (CO) reduces IRI. This study aimed to assess the effects of carbon monoxide-releasing molecule-2 (CORM-2) on intestinal mucosal barrier function in rats undergoing CPR.

Methods

We established a rat model of asphyxiation-induced cardiac arrest (CA) and resuscitation to study intestinal IRI, and measured the serum levels of intestinal fatty acid-binding protein. Morphological changes were investigated using light and electron microscopes. The expression levels of claudin 3 (CLDN3), occludin (OCLN), zonula occludens 1 (ZO-1), tumor necrosis factor-alpha (TNF-α), interleukin-10 (IL-10), and nuclear factor kappa B (NF-κB) p65 were detected by western blotting.

Results

Compared with the sham-operated group, histological changes and transmission electron microscopy revealed severe intestinal mucosal injury in the CPR and inactive CORM-2 (iCORM-2) groups. In contrast, CORM-2 alleviated intestinal IRI. CORM-2, unlike iCORM-2, markedly decreased the Chiu's scores (2.38 ± 0.38 vs. 4.59 ± 0.34; P < 0.05) and serum intestinal fatty acid-binding protein level (306.10 ± 19.22 vs. 585.64 ± 119.84 pg/mL; P < 0.05) compared with the CPR group. In addition, CORM-2 upregulated the expression levels of tight junction proteins (CLDN3, OCLN, and ZO-1) (P < 0.05) and downregulated those of IL-10, TNF-α, and NF-кB p65 (P < 0.05) in the ileum tissue of rats that received CPR.

Conclusions

CORM-2 prevented intestinal mucosal damage as a result of IRI during CPR. The underlying protective mechanism was associated with inhibition of ischemia-reperfusion-induced changes in intestinal epithelial permeability and inflammation in intestinal tissue.

Inverse Association Between Bystander Use of Audiovisual Feedback From an Automated External Defibrillator and Return of Spontaneous Circulation

Background

Treatment with an automated external defibrillator (AED) improves outcome in out‐of‐hospital cardiac arrest (OHCA). Audiovisual feedback from an AED may assist bystanders achieve higher quality cardiopulmonary resuscitation. However, the association between audiovisual feedback and clinical outcomes is not well assessed in real‐life OHCA. The aim of this study was to assess the association between audiovisual feedback from an AED used in bystander resuscitation with rates of return of spontaneous circulation (ROSC) and 30‐day survival in a real‐life cohort of patients with OHCA.

Methods and Results

We included 325 patients treated with bystander AED use before arrival of emergency medical services during 2016 to 2019 from the Capital Region of Denmark. Patients were divided into a “feedback” and a “nonfeedback” group, depending on presence of audiovisual feedback from the AED. Audiovisual feedback was defined as voice prompts with continuous feedback to ongoing resuscitation. Rates of ROSC upon hospital admission and 30‐day survival were assessed, and univariate and multivariable models were applied to decide the association to audiovisual feedback. Multivariable models were adjusted for sex, age, primary heart rhythm, and location of OHCA. A total of 155 (48%) patients had a bystander AED applied with audiovisual feedback and 170 (52%) without audiovisual feedback. A lower rate of ROSC was found in the feedback group compared with the nonfeedback group (33% [n=51] versus 45% [n=76]; P =0.03). No association was observed between AV feedback and 30‐day survival (feedback=27% [n=42] and nonfeedback=31% [n=53]; P =0.49). In the unadjusted logistic regression model, audiovisual feedback was associated with a decreased chance of ROSC (odds ratio, 0.61; 95% CI, 0.38–0.95; P =0.03), which remained significant after adjusted analysis (odds ratio, 0.53; 95% CI, 0.29–0.97; P =0.04), whereas we found no significant association between audiovisual feedback and 30‐day survival in the unadjusted and adjusted analyses.

Conclusions

Audiovisual feedback from an AED used by bystanders was associated with a lower chance of ROSC at hospital admission, but we found no significant difference in 30‐day survival. Focus on early and correct bystander cardiopulmonary resuscitation and AED use remain key for OHCA survival.

Endotracheal Intubation Versus No Endotracheal Intubation During Cardiopulmonary Arrest in the Emergency Department

Background

There is a lack of studies addressing the short and long-term outcomes of using different airway interventions in patients with cardiopulmonary arrest in the emergency department (ED). This retrospective chart review aimed to investigate the effect of endotracheal intubation (ETI) versus no ETI during cardiopulmonary arrest in the ED on return of spontaneous circulation (ROSC) and survival to discharge.

Methodology

A total of 168 charts were reviewed from August 2017 to April 2019. Resuscitation characteristics were obtained from Utstein-style-based cardiopulmonary arrest flow sheets.

Results

Unadjusted analysis showed no difference in ROSC (45.5% in ETI vs. 54.5% in no-ETI) (p = 0.08) and survival to hospital discharge at 28 days (26.7% in ETI vs. 73.3% in non-ETI) (p = 0.07) when comparing ETI versus non-ETI airway management methods during cardiopulmonary resuscitation (CPR). After adjusting for confounding factors, our regression analysis revealed that the use of ETI is associated with lower odds of ROSC (odds ratio [OR] = 3.40, 95% confidence interval [CI] = [0.14-0.84]) and survival to hospital discharge at 28 days (OR = 0.20, 95% CI = [0.04-0.84]).

Conclusions

ETI during CPR in the ED is associated with worse ROSC and survival to hospital discharge at 28 days.

Does the use of BariBoard™ improve adequacy of chest compressions in morbid obesity? A pilot study using a simulation model

BACKGROUND

Obesity is a growing health problem worldwide. Morbid obesity has been associated with significant barriers to effective thoracic cage compression during cardiopulmonary resuscitation.

OBJECTIVE

The BariBoard™ purports to improve adequacy of chest compressions in morbidly obese patients. This study uses a simulation model to evaluate this.

METHODS

This was a prospective blinded randomised-controlled crossover pilot trial using a simulation model of obesity. Participants, recruited from hospital departments and prehospital services, performed 2 minutes of continuous compressions on mannequins modified to emulate a morbidly obese patient. Participants were randomised by coin toss to a sequence of either control/intervention or intervention/control, with the BariBoard™ in the intervention arm. Accelerometers measured chest wall movement during compressions. The primary endpoint was a composite measure of compression adequacy (rate, depth, and recoil). Secondary endpoints comprised the individual components of the composite outcome, as both dichotomous outcomes (adequate vs. inadequate) and continuous variables. All endpoints were adjusted for potential confounders.

RESULTS

Of 205 participants recruited, 201 were analysed. There was a significant difference in the primary outcome between the control and intervention arms (13.4% vs. 4.5%, respectively, p = 0.001) and between the control and intervention arms for the secondary endpoints of adequate compression depth (31.3% vs. 15.9%, p < 0.001) and recoil (63.7% vs. 41.3%, p < 0.001). After adjustment for confounders and interactions, there was no difference in overall efficacy (odds ratio: 0.62, 95% confidence interval: 0.20-1.90, p = 0.40).

CONCLUSION

This pilot study describes the successful assessment of a device using a simulation model of obesity. Within these constraints and after adjustment for confounders, use of the BariBoard ™ did not improve efficacy of chest compressions.

A retrospective analysis of fibrinolytic and adjunctive antithrombotic treatment during cardiopulmonary resuscitation

Synergistic effects of fibrinolytic and additional antithrombotic treatment during cardiopulmonary resuscitation in out-of-hospital cardiac arrest of assumed cardiac origin were evaluated retrospectively. Data were drawn from electronic files of the physician-staffed Emergency Medical Services Tyrol. During a 22-month observation period 53 adult patients were treated with tenecteplase (mean 7641 IU), 19 (32.1%) of whom received additional antithrombotic treatment with heparin (4000-5000 IU) and acetylsalicylic acid (250-500 mg). Lasting return of spontaneous circulation occurred in four of 34 patients who received fibrinolytic treatment only and in seven of 19 patients with additional antithrombotic treatment (p = 0.037). Four of five patients who were discharged from hospital had received additional antithrombotic treatment during CPR and were in appropriate neurological status (CPC 1). Considering the small sample size in this retrospective study, the argument may be still be made that fibrinolytic and adjunctive antithrombotic treatment during cardiopulmonary resuscitation in out-of-hospital cardiac arrest of assumed cardiac origin may increase the chances for survival.

Hyperglycemia and Thrombocytopenia - Combinatorially Increase the Risk of Mortality in Patients With Acute Myocardial Infarction Undergoing Veno-Arterial Extracorporeal Membrane Oxygenation

Background: Patients with cardiogenic shock due to acute myocardial infarction (AMI) can rapidly undergo veno-arterial extracorporeal membrane oxygenation (VA-ECMO) therapy to recover cardiac output and decrease mortality. However, the clinical indicators predictive of mortality in these patients remain unknown.

Methods and Results: We conducted a single-center retrospective cohort study targeting AMI patients undergoing VA-ECMO. All 63 patients undergoing VA-ECMO for AMI at the Japanese Red Cross Kumamoto Hospital between January 1, 2010 and June 30, 2020 were enrolled. An exploratory analysis was conducted using a survival tree model and variables selected in a univariate Cox proportional hazard model. The median survival time from the start of VA-ECMO was 6.3 days, and 77.8% (n=49) of patients died. Survival analysis divided patients into 3 groups based on 2 parameters at the initial medical examination: Group 1, patients with neither hyperglycemia (blood glucose ≥213 mg/dL) nor thrombocytopenia (platelets ≤145,100/μL); Group 2, patients with hyperglycemia; and Group 3, patients with hyperglycemia plus thrombocytopenia. Relative to Group 1, the risk of in-hospital mortality was significantly increased in Group 2 (hazard ratio [HR] 2.25; 95% confidence interval [CI] 1.13–4.46), and that risk further increased in Group 3 (HR 7.60; 95% CI 3.21–17.95).

Conclusions: Hyperglycemia plus thrombocytopenia on initial medical examination combinatorially increase the risk of mortality in patients with cardiogenic shock due to AMI undergoing VA-ECMO.

Effects of cardiopulmonary resuscitation on direct versus video laryngoscopy using a mannequin model

INTRODUCTION

During the last decade, guidelines for cardiopulmonary resuscitation has shifted, placing chest compressions and defibrillation first and airway management second. Physicians are being forced to intubate simultaneously with uninterrupted, high quality chest compressions. Using a mannequin model, this study examines the differences between direct and video laryngoscopy, comparing their performance with and without simultaneous chest compressions.

METHODS

Fifty emergency medicine physicians were randomly assigned to intubate a mannequin six times, using direct laryngoscopy (DL) and with two video laryngoscopy (VL) systems, a C-MAC traditional Macintosh blade and a GlideScope hyperangulated blade, with and without simultaneous chest compressions. A total of 300 intubations were completed and variables including intubation times, accuracy, difficulty, success rates and glottic views were recorded.

RESULTS

The C-MAC VL system resulted in quicker intubations compared to DL (p = 0.007) and the GlideScope VL system (p = 0.039) during active chest compressions. Compared to DL, intubations were rated easier for both the C-MAC (p < 0.0001) and the GlideScope (p < 0.0001). Intubation failure rates were also higher when DL was used compared to either the C-MAC or GlideScope (p = 0.029). VL devices provided a superior overall Cormack-Lehane grade view compared to DL (p < 0.0001). The presence of chest compressions significantly impaired Cormack-Lehane views during direct laryngoscopy (p = 0.007). Chest compressions made the intubation more difficult under DL (p = 0.002) and when using the C-MAC (p = 0.031). Chest compressions also made ETT placement less accurate when using DL (p = 0.004).

CONCLUSION

Using a mannequin model, the C-MAC conventional VL blade resulted in decrease intubation times compared with DL or the GlideScope hyperangulated VL blade system. Overall, VL out performed DL in terms of providing a superior glottic view, minimizing failed attempts, and improving physician's overall perception of intubation difficulty. Chest compressions resulted in worse Cormack-Lehane views and higher rates of inaccurate endotracheal tube placement with DL, compared to VL.

Effect of positive end-expiratory pressure on additional passive ventilation generated by CPR compressions in a porcine model

Background

Compressions given during cardiopulmonary resuscitation generate small, ineffective passive ventilations through oscillating waves. Positive end-expiratory pressure increases the volume of these passive ventilations; however, its effect on passive ventilation is unknown. Our objective was to determine if increasing positive end-expiratory pressure during cardiopulmonary resuscitation increases passive ventilation generated by compressions to a clinically significant point. This study was conducted on 13 Landrace-Yorkshire pigs. After inducing cardiac arrest with bupivacaine, cardiopulmonary resuscitation was performed with a LUCAS 3.1. During cardiopulmonary resuscitation, pigs were ventilated at a positive end-expiratory pressure of 0, 5, 10, 15, 20 cmH₂O (randomly determined) for 9 min. Using the NM3 respiratory monitoring device, expired minute ventilation and volumetric capnography were measured. Arterial blood gas was obtained for each positive end-expiratory pressure level to compare the effects of positive end-expiratory pressure on carbon dioxide.

Results

Increasing positive end-expiratory pressure from 0 to 20 cmH₂O increased the mean (SEM) expired minute ventilation from 6.33 (0.04) to 7.33 (0.04) mL/min. With the 5-cmH₂O incremental increases in positive end-expiratory pressure from 0 to 20 cmH₂O, volumetric capnography increased from a mean (SEM) of 94.19 (0.78) to 115.18 (0.8) mL/min, except for 15 cmH₂O, which showed greater carbon dioxide exhalation with volumetric capnography compared with 20 cmH₂O. PCO₂ declined significantly as positive end-expiratory pressure was increased from 0 to 20 cmH₂O.

Conclusions

When increasing positive end-expiratory pressure from 0 to 20, the contribution to overall ventilation from gas oscillations generated by the compressions became more significant, and may even lead to hypocapnia, especially when using positive end-expiratory pressures between 15 and 20.

Different forms of bystander cardiopulmonary resuscitation in out-of-hospital cardiac arrest

Out-of-hospital cardiac arrest (OHCA) is a major cause of death in the Western world with an estimated number of 275 000 treated with resuscitation attempts by the Emergency Medical Services (EMS) in Europe each year. Overall survival rates remain low, and most studies indicate that around 1 out 10 will survive to 30 days. Amongst the strongest factors associated with survival in OHCA is first recorded rhythm amendable to defibrillation, early defibrillation and prompt initiation of cardiopulmonary resuscitation (CPR). Overall, CPR started prior to EMS arrival has repeatedly been shown to be associated with survival rates 2-3 times higher compared with no such initiation. The primary goal of CPR is to generate sufficient blood flow to vital organs, mainly the brain and heart, until restoration of spontaneous circulation can be achieved. Barriers to the initiation of CPR by bystanders in OHCA include fear of being incapable, causing harm, and transmission of infectious diseases. Partly due to these barriers, and low rates of CPR, the concept of CPR with compression only was proposed as a simpler form of resuscitation with the aim to be more widely accepted by the public in the 1990s. But how reliable is the evidence supporting this simpler form of CPR, and are the outcomes after CO-CPR comparable to standard CPR?

Mathematical model of modified hybrid pump mechanism for cardiopulmonary resuscitation

BACKGROUND AND OBJECTIVE

The "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.

METHODS

By 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.

RESULTS

The 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.

CONCLUSION

Comparison 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.

Effects of mechanical ventilation with expiratory negative airway pressure on porcine pulmonary and systemic circulation: mechano-physiology and potential application

We studied the impact of mechanically regulated, expiratory negative airway pressure (ENAP) ventilation on pulmonary and systemic circulation including its mechanisms and potential applications. Microminipigs weighing about 10 kg were anesthetized (n = 5). First, hemodynamic variables were evaluated without and with ENAP to approximately -16 cmH2O. ENAP significantly increased heart rate and cardiac output, but decreased right atrial, pulmonary arterial and pulmonary capillary wedge pressures. Second, the evaluation was repeated following pharmacological adrenergic blockade, modestly blunting ENAP effects. Third, fluvoxamine (10 mg/kg) was intravenously administered to intentionally induce cardiovascular collapse in the presence of adrenergic blockade. ENAP was started when systolic pressure was < 40 mmHg in the animals assigned to ENAP treatment-group. Fluvoxamine induced cardiovascular collapse within 4 out of 5 animals. ENAP increased systolic pressure to > 50 mmHg (n = 2): both animals fully recovered without neurological deficit, whereas without ENAP both animals died of cardiac arrest (n = 2). ENAP may become an innovative treatment for drug-induced cardiovascular collapse.