Haemodynamic effects of descending aortic occlusion during cardiopulmonary resuscitation

Resuscitative endovascular balloon occlusion of the aorta (REBOA) during cardiac resuscitation increased cerebral perfusion to occurrence of cardiopulmonary resuscitation-induced consciousness, a case report

Consciousness or signs of life may be seen during cardiopulmonary resuscitation (CPR), without return of spontaneous circulation. Such CPR-induced consciousness includes breathing efforts, eye opening, movements of extremities or communication with the rescuers. The consciousness may be CPR-interfering or non-interfering, and typically ends when the resuscitation efforts end. Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a potential adjunct treatment to CPR and may increase the arterial blood pressure. We present a case where REBOA increased the arterial blood pressure to the extent that CPR-induced consciousness was seen.

Extremity tourniquets raise blood pressure and maintain heart rate

BACKGROUND

Tourniquets have been modified and used for centuries to occlude blood flow to control hemorrhage. More recently, the occlusion of peripheral vessels has been linked to resultant increases in blood pressure, which may provide additional therapeutic potential, particularly during states of low cardiac output.

OBJECTIVE

The objective of this study was to investigate a causal relationship between tourniquet application and blood pressure in healthy adults.

METHODS

Healthy adult volunteers were recruited to participate in this IRB-approved study. Each participant met inclusion criteria and demonstrated baseline normotension. Brachial cuff blood pressure and heart rate were recorded pre- and post-tourniquet application to the bilateral legs.

RESULTS

Twenty-seven adults aged 22 to 35 years participated and were included in analysis. The average systolic blood pressure was 122 ± 7 mmHg, diastolic blood pressure was 72 ± 9 mmHg, and heart rate was 70 ± 13 bpm. Following bilateral tourniquet application over the femoral vasculature, we observed a statistically significant increase in systolic (7 mmHg, p < 0.001) and diastolic (4 mmHg, p = 0.05) blood pressures with no significant change in heart rate (2 bpm, p > 0.05).

CONCLUSIONS

The elevations in systolic and diastolic blood pressures establish a dependent relationship between tourniquet application to the lower extremities and blood pressure elevation. These results may support new indications for tourniquet-use or extremity vessel occlusion in settings of hemodynamic instability.

Advanced and Invasive Cardiopulmonary Resuscitation (CPR) Techniques as an Adjunct to Advanced Cardiac Life Support

BACKGROUND

Despite numerous promising innovations, the chance of survival from sudden cardiac arrest has remained virtually unchanged for decades. Recently, technological advances have been made, user-friendly portable devices have been developed, and advanced invasive procedures have been described that could improve this unsatisfactory situation.

METHODS

A selective literature search in the core databases with a focus on randomized controlled trials and guidelines.

RESULTS

Technical aids, such as feedback systems or automated mechanical cardiopulmonary resuscitation (CPR) devices, can improve chest compression quality. The latter, as well as extracorporeal CPR, might serve as a bridge to treatment (with extracorporeal CPR even as a bridge to recovery). Sonography may be used to improve thoracic compressions on the one hand and to rule out potentially reversible causes of cardiac arrest on the other. Resuscitative endovascular balloon occlusion of the aorta might enhance myocardial and cerebral perfusion. Minithoracostomy, pericardiocentesis, or clamshell thoracotomy might resolve reversible causes of cardiac arrest.

CONCLUSIONS

It is crucial to identify those patients who may benefit from an advanced or invasive procedure and make the decision to implement the intervention in a timely manner. As with all infrequently performed procedures, sound education and regular training are paramount.

Automated aortic endovascular balloon volume titration prevents re-arrest immediately after return of spontaneous circulation in a swine model of nontraumatic cardiac arrest

Objectives

Endovascular aortic occlusion as an adjunct to cardiopulmonary resuscitation (CPR) for non-traumatic cardiac arrest is gaining interest. In a recent clinical trial, return of spontaneous circulation (ROSC) was achieved despite prolonged no-flow times. However, 66% of patients re-arrested upon balloon deflation. We aimed to determine if automated titration of endovascular balloon volume following ROSC can augment diastolic blood pressure (DBP) to prevent re-arrest.

Methods

Twenty swine were anesthetized and placed into ventricular fibrillation (VF). Following 7 minutes of no-flow VF and 5 minutes of mechanical CPR, animals were subjected to complete aortic occlusion to adjunct CPR. Upon ROSC, the balloon was either deflated steadily over 5 minutes (control) or underwent automated, dynamic adjustments to maintain a DBP of 60 mmHg (Endovascular Variable Aortic Control, EVAC).

Results

ROSC was obtained in ten animals (5 EVAC, 5 REBOA). Sixty percent (3/5) of control animals rearrested while none of the EVAC animals rearrested (p = 0.038). Animals in the EVAC group spent a significantly higher proportion of the post-ROSC period with a DBP > 60 mmHg [median (IQR)] [control 79.7 (72.5–86.0)%; EVAC 97.7 (90.8–99.7)%, p = 0.047]. The EVAC group had a statistically significant reduction in arterial lactate concentration [7.98 (7.4–8.16) mmol/L] compared to control [9.93 (8.86–10.45) mmol/L, p = 0.047]. There were no statistical differences between the two groups in the amount of adrenaline (epinephrine) required.

Conclusion

In our swine model of cardiac arrest, automated aortic endovascular balloon titration improved DBP and prevented re-arrest in the first 20 minutes after ROSC.

Changes in peripheral arterial blood pressure after resuscitative endovascular balloon occlusion of the aorta (REBOA) in non-traumatic cardiac arrest patients

Background

Resuscitative endovascular balloon occlusion of the aorta (REBOA) may be an adjunct treatment to cardiopulmonary resuscitation (CPR). Aortic occlusion may increase aortic pressure and increase the coronary perfusion pressure and the cerebral blood flow. Peripheral arterial blood pressure is often measured during or after CPR, however, changes in peripheral blood pressure after aortic occlusion is insufficiently described. This study aimed to assess changes in peripheral arterial blood pressure after REBOA in patients with out of hospital cardiac arrest.

Methods

A prospective observational study performed at the helicopter emergency medical service in Trondheim (Norway). Eligible patients received REBOA as adjunct treatment to advanced cardiac life support. Peripheral invasive arterial blood pressure and end-tidal CO₂ (EtCO₂) was measured before and after aortic occlusion. Differences in arterial blood pressures and EtCO₂ before and after occlusion was analysed with Wilcoxon Signed Rank test.

Results

Five patients were included to the study. The median REBOA procedural time was 11 min and median time from dispatch to aortic occlusion was 50 min. Two patients achieved return of spontaneous circulation. EtCO₂ increased significantly 60 s after occlusion, by a mean of 1.16 kPa (p = 0.043). Before occlusion the arterial pressure in the compression phase were 43.2 (range 12–112) mmHg, the mean pressure 18.6 (range 4–27) mmHg and pressure in the relaxation phase 7.8 (range − 7 – 22) mmHg. After aortic occlusion the corresponding pressures were 114.8 (range 23–241) mmHg, 44.6 (range 15–87) mmHg and 14.8 (range 0–29) mmHg. The arterial pressures were significant different in the compression phase and as mean pressure (p = 0.043 and p = 0.043, respectively) and not significant in the relaxation phase (p = 0.223).

Conclusion

This study is, to our knowledge, the first to assess the peripheral invasive arterial blood pressure response to aortic occlusion during CPR in the pre-hospital setting. REBOA application during CPR is associated with a significantly increase in peripheral artery pressures. This likely indicates improved central aortic blood pressure and warrants studies with simultaneous peripheral and central blood pressure measurement during aortic occlusion.

Trial registration

The study is registered in ClinicalTrials.gov (NCT03534011).

REBOARREST, resuscitative endovascular balloon occlusion of the aorta in non-traumatic out-of-hospital cardiac arrest: a study protocol for a randomised, parallel group, clinical multicentre trial

Background

Survival after out-of-hospital cardiac arrest (OHCA) is poor and dependent on high-quality cardiopulmonary resuscitation. Resuscitative endovascular balloon occlusion of the aorta (REBOA) may be advantageous in non-traumatic OHCA due to the potential benefit of redistributing the cardiac output to organs proximal to the aortic occlusion. This theory is supported by data from both preclinical studies and human case reports.

Methods

This multicentre trial will enrol 200 adult patients, who will be randomised in a 1:1 ratio to either a control group that receives advanced cardiovascular life support (ACLS) or an intervention group that receives ACLS and REBOA. The primary endpoint will be the proportion of patients who achieve return of spontaneous circulation with a duration of at least 20 min. The secondary objectives of this trial are to measure the proportion of patients surviving to 30 days with good neurological status, to describe the haemodynamic physiology of aortic occlusion during ACLS, and to document adverse events.

Discussion

Results from this study will assess the efficacy and safety of REBOA as an adjunctive treatment for non-traumatic OHCA. This novel use of REBOA may contribute to improve treatment for this patient cohort.

Trial registration

The trial is approved by the Regional Committee for Medical and Health Research Ethics in Norway (reference 152504) and is registered at ClinicalTrials.gov (reference NCT04596514) and as Universal Trial Number WHO: U1111-1253-0322.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05477-1.

Optimizing hemodynamic function during cardiopulmonary resuscitation

PURPOSE OF REVIEW

The purpose of this narrative review is to provide an update on hemodynamics during cardiopulmonary resuscitation (CPR) and to describe emerging therapies to optimize perfusion.

RECENT FINDINGS

Cadaver studies have shown large inter-individual variations in blood distribution and anatomical placement of the heart during chest compressions. Using advanced CT techniques the studies have demonstrated atrial and slight right ventricular compression, but no direct compression of the left ventricle. A hemodynamic-directed CPR strategy may overcome this by allowing individualized hand-placement, drug dosing, and compression rate and depth. Through animal studies and one clinical before-and-after study head-up CPR has shown promising results as a potential strategy to improve cerebral perfusion. Two studies have demonstrated that placement of an endovascular balloon occlusion in the aorta (REBOA) can be performed during ongoing CPR.

SUMMARY

Modern imaging techniques may help increase our understanding on the mechanism of forward flow during CPR. This could provide new information on how to optimize perfusion. Head-up CPR and the use of REBOA during CPR are novel methods that might improve cerebral perfusion during CPR; both techniques do, however, still await clinical testing.

Randomized blinded trial of automated REBOA during CPR in a porcine model of cardiac arrest

BACKGROUND

Resuscitative endovascular balloon occlusion of the aorta (REBOA) reportedly elevates arterial blood pressure (ABP) during non-traumatic cardiac arrest.

OBJECTIVES

This randomized, blinded trial of cardiac arrest in pigs evaluated the effect of automated REBOA two minutes after balloon inflation on ABP (primary endpoint) as well as arterial blood gas values and markers of cerebral haemodynamics and metabolism.

METHODS

Twenty anesthetized pigs were randomized to REBOA inflation or sham-inflation (n = 10 in each group) followed by insertion of invasive monitoring and a novel, automated REBOA catheter (NEURESCUE® Catheter & NEURESCUE® Assistant). Cardiac arrest was induced by ventricular pacing. Cardiopulmonary resuscitation was initiated three min after cardiac arrest, and the automated REBOA was inflated or sham-inflated (blinded to the investigators) five min after cardiac arrest.

RESULTS

In the inflation compared to the sham group, mean ABP above the REBOA balloon after inflation was higher (inflation: 54 (95%CI: 43-65) mmHg; sham: 44 (33-55) mmHg; P = 0.06), and diastolic ABP was higher (inflation: 38 (29-47) mmHg; sham: 26 (20-33) mmHg; P = 0.02), and the arterial to jugular oxygen content difference was lower (P = 0.04). After return of spontaneous circulation, mean ABP (inflation: 111 (95%CI: 94-128) mmHg; sham: 94 (95%CI: 65-123) mmHg; P = 0.04), diastolic ABP (inflation: 95 (95%CI: 78-113) mmHg; sham: 78 (95%CI: 50-105) mmHg; P = 0.02), CPP (P = 0.01), and brain tissue oxygen tension (inflation: 315 (95%CI: 139-491)% of baseline; sham: 204 (95%CI: 75-333)%; P = 0.04) were higher in the inflation compared to the sham group.

CONCLUSION

Inflation of REBOA in a porcine model of non-traumatic cardiac arrest improves central diastolic arterial pressure as a surrogate marker of coronary artery pressure, and cerebral perfusion.

INSTITUTIONAL PROTOCOL NUMBER

2017-15-0201-01371.

The use of resuscitative endovascular balloon occlusion of the aorta (REBOA) for non-traumatic cardiac arrest: A review

Resuscitative endovascular balloon occlusion of the aorta (REBOA) has been proposed as a novel approach to managing non-traumatic cardiac arrest (NTCA). During cardiac arrest, cardiac output ceases and perfusion of vital organs is compromised. Traditional advanced cardiac life support (ACLS) measures and cardiopulmonary resuscitation are often unable to achieve return of spontaneous circulation (ROSC). During insertion of REBOA a balloon-tipped catheter is placed into the femoral artery and advanced in a retrograde manner into the aorta while the patient is undergoing cardiopulmonary resuscitation (CPR). The balloon is then inflated to fully occlude the aorta. The literature surrounding the use of aortic occlusion in non-traumatic cardiac arrest is limited to animal studies, case reports and one recent non-controlled feasibility trial. In both human and animal studies, preliminary data show that REBOA may improve coronary and cerebral perfusion pressures and key physiologic parameters during cardiac arrest resuscitation, and animal data have demonstrated improved rates of ROSC. Multiple questions remain before REBOA can be considered as an adjunct to ACLS. If demonstrated to be effective clinically, REBOA represents a potentially cost-effective and generalizable intervention that may improve quality of life for patients with non-traumatic cardiac arrest.

The Effect of Chest Compression Location and Aortic Perfusion in a Traumatic Arrest Model

BACKGROUND

Recent evidence demonstrates that closed chest compressions directly over the left ventricle (LV) in a traumatic cardiac arrest (TCA) model improve hemodynamics and return of spontaneous circulation (ROSC) when compared to traditional compressions. Selective aortic arch perfusion (SAAP) also improves hemodynamics and controls hemorrhage in TCA. We hypothesized that chest compressions located over the LV would result in improved hemodynamics and ROSC in a swine model of TCA using SAAP.

MATERIALS AND METHODS

Transthoracic echo was used to mark the location of the aortic root (Traditional location) and the center of the LV on animals (n = 24), which were randomized to receive chest compressions in one of the two locations. After hemorrhage, ventricular fibrillation (VF) was induced to simulate TCA. After a period of 10 min of VF, basic life support (BLS) with mechanical CPR was initiated and performed for 10 min, followed by advanced life support (ALS) for an additional 10 min. SAAP balloons were inflated at min 6 of BLS. Hemodynamic variables were averaged over the final 2 min of the BLS and ALS periods. Survival was compared between this SAAP cohort and a control group without SAAP (No-SAAP) (n = 26).

RESULTS

There was no significant difference in ROSC between the two SAAP groups (P = 0.67). There was no ROSC difference between SAAP and No-SAAP (P = 0.74).

CONCLUSIONS

There was no difference in ROSC between LV and Traditional compressions when SAAP was used in this swine model of TCA. SAAP did not confer a survival benefit compared to historical controls.

Resuscitative Endovascular Balloon Occlusion of the Aorta in Experimental Cardiopulmonary Resuscitation: Aortic Occlusion Level Matters

Introduction:

Aortic occlusion during cardiopulmonary resuscitation (CPR) increases systemic arterial pressures. Correct thoracic placement during the resuscitative endovascular balloon occlusion of the aorta (REBOA) may be important for achieving effective CPR.

Hypothesis:

The positioning of the REBOA in the thoracic aorta during CPR will affect systemic arterial pressures.

Methods:

Cardiac arrest was induced in 27 anesthetized pigs. After 7 min of CPR with a mechanical compression device, REBOA in the thoracic descending aorta at heart level (zone Ib, REBOA-Ib, n = 9), at diaphragmatic level (zone Ic, REBOA-Ic, n = 9) or no occlusion (control, n = 9) was initiated. The primary outcome was systemic arterial pressures during CPR.

Results:

During CPR, REBOA-Ic increased systolic blood pressure from 86 mmHg (confidence interval [CI] 71–101) to 128 mmHg (CI 107–150, P < 0.001). Simultaneously, mean and diastolic blood pressures increased significantly in REBOA-Ic (P < 0.001 and P = 0.006, respectively), and were higher than in REBOA-Ib (P = 0.04 and P = 0.02, respectively) and control (P = 0.005 and P = 0.003, respectively). REBOA-Ib did not significantly affect systemic blood pressures. Arterial pH decreased more in control than in REBOA-Ib and REBOA-Ic after occlusion (P = 0.004 and P = 0.005, respectively). Arterial lactate concentrations were lower in REBOA-Ic compared with control and REBOA-Ib (P = 0.04 and P < 0.001, respectively).

Conclusions:

Thoracic aortic occlusion in zone Ic during CPR may be more effective in increasing systemic arterial pressures than occlusion in zone Ib. REBOA during CPR was found to be associated with a more favorable acid–base status of circulating blood. If REBOA is used as an adjunct in CPR, it may be of importance to carefully determine the aortic occlusion level.

The study was performed following approval of the Regional Animal Ethics Committee in Linköping, Sweden (application ID 418).

[Resuscitative endovascular balloon occlusion of the aorta (REBOA) : Current aspects of material, indications and limits: an overview]

Hintergrund

„Resuscitative endovascular balloon occlusion of the aorta“ (REBOA) stellt ein endovaskuläres Verfahren dar, bei dem ein Blockballon in die Aorta eingeführt wird, um eine distal des Ballons gelegene Blutung zu verringern und gleichzeitig die kardiale und zerebrale Oxygenierung zu verbessern.

Ziel der Arbeit

Vorstellung der REBOA-Technik, der möglichen Indikationen, der benötigen Materialien und der möglichen Komplikationen des Verfahrens.

Material und Methoden

Nichtsystematischer Übersichtsartikel über die aktuelle Literatur.

Ergebnisse

REBOA stellt gerade bei traumatisch bedingten Blutungen und rupturierten Aortenaneurysmen ein mögliches additives Verfahren zur hämodynamischen Stabilisierung dar. Die Komplikationsrate des Verfahrens liegt bei ungefähr 5 %, wobei Zugangskomplikationen im Vordergrund stehen, jedoch auch letale Komplikationen möglich sind.

Diskussion

Eine aortale Ballonblockade wird bei der Versorgung rupturierter Aortenaneurysmen standardmäßig eingesetzt. Es gibt wachsende Evidenz, dass REBOA bei der Versorgung polytraumatisierter Patienten mit einem hämorrhagischen Schock aufgrund einer abdominellen oder viszeralen Blutung eine vergleichsweise minimal-invasive Alternative zur offen chirurgischen Aortenklemmung mittels Thorakotomie darstellt. Mit der Entwicklung neuer Ballonkatheter, die ohne Führungsdraht und mit geringeren Schleusendurchmessern auskommen, wird auch ein Einsatz bei anderen Krankheitsbildern wie postoperativen abdominellen Nachblutungen, gynäkologischen Blutungen oder als additives Verfahren bei der kardiopulmonalen Reanimation diskutiert.

The Effect of Chest Compression Location and Occlusion of the Aorta in a Traumatic Arrest Model

BACKGROUND

Recent evidence demonstrates that closed chest compressions directly over the left ventricle (LV) in a traumatic cardiac arrest (TCA) model improve hemodynamics and return of spontaneous circulation (ROSC) when compared with traditional compressions. Resuscitative endovascular balloon occlusion of the aorta (REBOA) also improves hemodynamics and controls hemorrhage in TCA. We hypothesized that chest compressions located over the LV would result in improved hemodynamics and ROSC in a swine model of TCA using REBOA.

MATERIALS AND METHODS

Transthoracic echo was used to mark the location of the aortic root (traditional location) and the center of the LV on animals (n = 26), which were randomized to receive chest compressions in one of the two locations. After hemorrhage, ventricular fibrillation was induced to simulate TCA. After a period of 10 min of ventricular fibrillation, basic life support (BLS) with mechanical cardiopulmonary resuscitation was initiated and performed for 10 min followed by advanced life support for an additional 10 min. REBOA balloons were inflated at 6 min into BLS. Hemodynamic variables were averaged during the final 2 min of the BLS and advanced life support periods. Survival was compared between this REBOA cohort and a control group without REBOA (no-REBOA cohort) (n = 26).

RESULTS

There was no significant difference in ROSC between the two REBOA groups (P = 0.24). Survival was higher with REBOA group versus no-REBOA group (P = 0.02).

CONCLUSIONS

There was no difference in ROSC between LV and traditional compressions when REBOA was used in this swine model of TCA. REBOA conferred a survival benefit regardless of compression location.

Training and assessment of competence in resuscitative endovascular balloon occlusion of the aorta (REBOA) - a systematic review

BACKGROUND

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a potentially life-saving but high-risk emergency procedure in patients with haemorrhagic shock. Lack of physicians with competence in the procedure is a barrier to implementation of REBOA. It is currently unclear how training and assessment of competence should be done.

OBJECTIVES

To report and evaluate research in training and assessment of competence in REBOA and femoral arterial access with the aim to investigate the effect of simulation-based training in the procedure and to provide suggestions for the future design of training programs and assessment tools.

METHODS

Following PRISMA guidelines, PubMed, Embase, and Cochrane Library databases were searched for studies on training or assessment of competence in REBOA and femoral arterial access. Bias assessment was done using the Medical Education Research Study Quality Instrument. Evidence level was assessed using GRADE.

RESULTS

Sixteen studies were included, six of them published as abstracts. Full-text studies included 189 trainees ranging in experience level from military medics to surgical specialists. Outcome measures were heterogenous; the most used were rater checklists, knowledge testing, and procedure time. All studies confirmed an effect of training of REBOA on procedural competence in a simulation setting but had a high degree of bias. No study developed or used an assessment tool supported by validity evidence and no study investigated mid and long-term outcomes.

CONCLUSION

Simulation-based training of REBOA improves skills, however, the evidence level is very low and data cannot answer important questions on effect size, skill transfer and retention, and optimal course design. To advance research and training programmes, an assessment tool supported by validity evidence with broad applicability is needed.

Feasibility of Pre-Hospital Resuscitative Endovascular Balloon Occlusion of the Aorta in Non-Traumatic Out-of-Hospital Cardiac Arrest

Background

Few patients survive after out‐of‐hospital cardiac arrest and any measure that improve circulation during cardiopulmonary resuscitation is beneficial. Animal studies support that resuscitative endovascular balloon occlusion of the aorta (REBOA) during cardiopulmonary resuscitation might benefit patients suffering from out‐of‐hospital cardiac arrest, but human data are scarce.

Methods and Results

We performed an observational study at the helicopter emergency medical service in Trondheim (Norway) to assess the feasibility and safety of establishing REBOA in patients with out‐of‐hospital cardiac arrest. All patients received advanced cardiac life support during the procedure. End‐tidal CO₂ was measured before and after REBOA placement as a proxy measure of central circulation. A safety‐monitoring program assessed if the procedure interfered with the quality of advanced cardiac life support. REBOA was initiated in 10 patients. The mean age was 63 years (range 50–74 years) and 7 patients were men. The REBOA procedure was successful in all cases, with 80% success rate on first cannulation attempt. Mean procedural time was 11.7 minutes (SD 3.2, range 8–16). Mean end‐tidal CO₂ increased by 1.75 kPa after 60 seconds compared with baseline (P<0.001). Six patients achieved return of spontaneous circulation (60%), 3 patients were admitted to hospital, and 1 patient survived past 30 days. The safety‐monitoring program identified no negative influence on the advanced cardiac life support quality.

Conclusions

To our knowledge, this is the first study to demonstrate that REBOA is feasible during non‐traumatic out‐of‐hospital cardiac arrest. The REBOA procedure did not interfere with the quality of the advanced cardiac life support. The significant increase in end‐tidal CO₂ after occlusion suggests improved organ circulation during cardiopulmonary resuscitation.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unique identifier: NCT03534011.

Resuscitative Endovascular Balloon Occlusion of the Aorta for Refractory Out-of-Hospital Non-Traumatic Cardiac Arrest – A Case Report

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a percutaneous transfemoral balloon technique used in select centers for resuscitation and temporary hemostasis of bleeding patients. Several animal studies demonstrated that its application in non-traumatic cardiac arrest could enhance cerebral and coronary perfusion during cardiopulmonary resuscitation (CPR); despite this, there are few reports of its application in humans. This is a case report of REBOA application during a refractory out-of-hospital cardiac arrest in a 50-year-old man where Advanced Cardiac Life Support (ACLS) alone was unable to maintain a stable return of spontaneous circulation (ROSC) and Extracorporeal Cardiac Life Support (ECLS) was not available.

Resuscitative Endovascular Balloon Occlusion of the Aorta: Review of the Literature and Applications to Veterinary Emergency and Critical Care

While hemorrhagic shock might be the result of various conditions, hemorrhage control and resuscitation are the corner stone of patient management. Hemorrhage control can prove challenging in both the acute care and surgical settings, especially in the abdomen, where no direct pressure can be applied onto the source of bleeding. Resuscitative endovascular balloon occlusion of the aorta (REBOA) has emerged as a promising replacement to resuscitative thoracotomy (RT) for the management of non-compressible torso hemorrhage in human trauma patients. By inflating a balloon at specific levels (or zones) of the aorta to interrupt blood flow, hemorrhage below the level of the balloon can be controlled. While REBOA allows for hemorrhage control and augmentation of blood pressure cranial to the balloon, it also exposes caudal tissue beds to ischemia and the whole body to reperfusion injury. We aim to introduce the advantages of REBOA while reviewing known limitations. This review outlines a step-by-step approach to REBOA implementation, and discusses common challenges observed both in human patients and during translational large animal studies. Currently accepted and debated indications for REBOA in humans are discussed. Finally, we review possible applications for veterinary patients and how REBOA has the potential to be translated into clinical veterinary practice.

Resuscitative endovascular balloon occlusion of the aorta (REBOA) in non-traumatic out-of-hospital cardiac arrest: evaluation of an educational programme

BACKGROUND

Out-of-hospital cardiac arrest (OHCA) is a critical incident with a high mortality rate. Augmentation of the circulation during cardiopulmonary resuscitation (CPR) might be beneficial. Use of resuscitative endovascular balloon occlusion of the aorta (REBOA) redistribute cardiac output to the organs proximal to the occlusion. Preclinical data support that patients in non-traumatic cardiac arrest might benefit from REBOA in the thoracic level during CPR. This study describes a training programme to implement the REBOA procedure to a prehospital working team, in preparation to a planned clinical study.

METHODS

We developed a team-based REBOA training programme involving the physicians and paramedics working on the National Air Ambulance helicopter base in Trondheim, Norway. The programme consists of a four-step approach to educate, train and implement the REBOA procedure in a simulated prehospital setting. An objective structured assessment of prehospital REBOA application scoring chart and a special designed simulation mannequin was made for this study.

RESULTS

Seven physicians and 3 paramedics participated. The time needed to perform the REBOA procedure was 8.5 (6.3-12.7) min. The corresponding time from arrival at scene to balloon inflation was 12.0 (8.8-15) min. The total objective assessment scores of the candidates' competency was 41.8 (39-43.5) points out of 48. The advanced cardiovascular life support (ACLS) remained at standard quality, regardless of the simultaneous REBOA procedure.

CONCLUSION

This four-step approach to educate, train and implement the REBOA procedure to a prehospital working team ensures adequate competence in a simulated OHCA setting. The use of a structured training programme and objective assessment of skills is recommended before utilising the procedure in a clinical setting. In a simulated setting, the procedure does not add significant time to the prehospital resuscitation time nor does the procedure interfere with the quality of the ACLS.

TRIAL REGISTRATION NUMBER

NCT03534011.

The role of resuscitative endovascular balloon occlusion of the aorta (REBOA) as an adjunct to ACLS in non-traumatic cardiac arrest

Non-traumatic cardiac arrest is a major public health problem that carries an extremely high mortality rate. If we hope to increase the survivability of this condition, it is imperative that alternative methods of treatment are given due consideration. Balloon occlusion of the aorta can be used as a method of circulatory support in the critically ill patient. Intra-aortic balloon pumps have been used to temporize patients in cardiogenic shock for decades. More recently, resuscitative endovascular balloon occlusion of the aorta (REBOA) has been utilized in the patient in hemorrhagic shock or cardiac arrest secondary to trauma. Aortic occlusion in non-traumatic cardiac arrest has the effect of reducing the vascular volume that the generated cardiac output is distributed across. This augments myocardial and cerebral perfusion, increasing the probability of a return to a good quality of life for the patient. This phenomenon has been the subject of numerous animal studies dating back to the early 1980s; however, the human evidence is limited to several small case series. Animal research has demonstrated improvements in cerebral and coronary perfusion pressure during ACLS that lead to statistically significant differences in mortality. Several case series in humans have replicated these findings, suggesting the efficacy of this procedure. The objectives of this review are to: 1) introduce the reader to REBOA 2) review the physiology of NTCA and examine the current limitations of traditional ACLS 3) summarize the literature regarding the efficacy and feasibility of aortic balloon occlusion to support traditional ACLS.

Intraaortic counterpulsation during cardiopulmonary bypass impairs distal organ perfusion

BACKGROUND

Recent studies have focused on the use of fixed-rate intraaortic balloon pumping (IABP) during cardiopulmonary bypass (CPB) to achieve pulsatile flow. Because application of an IABP catheter may represent a functional obstruction within the descending aorta, we explored the effect of IABP-pulsed CPB-perfusion with special attention to perfusion above and below the IABP balloon.

METHODS

Sixteen animals received an IABP catheter that remained turned off position (NP group, n = 8) or was switched to an automatic mode of 80 beats/min during CPB (PP group, n = 8). Flow-data and pressure-data were obtained above and below the IABP balloon. Tissue perfusion was evaluated by microspheres.

RESULTS

IABP-pulsed CPB-perfusion, as assessed at 30 minutes on CPB, increased proximal mean aortic pressure (p < 0.05) and carotid artery blood flow (p < 0.001), but decreased distal mean aortic pressure (p < 0.001). The decrease of distal mean aortic pressure in the PP group was associated with a 75 % decrease (p < 0.001) of renal tissue perfusion. During nonpulsed perfusion the respective variables remained essentially unchanged compared with pre-CPB levels.

CONCLUSIONS

Using IABP as a surrogate to achieve pulsatile perfusion during CPB contributes significantly to lowered aortic pressure in the distal portion of aorta and impaired tissue perfusion of the kidneys. The results are focusing on effects that may contribute to organ dysfunction and acute kidney injury. Consequently, assessment of perfusion pressure distal to the balloon should be addressed whenever IABP is used during CPB.

Effect of intra-aortic occlusion balloon in external thoracic compressions during CPR in pigs

This study was performed to compare the effectiveness of external thoracic compressions with and without intra-aortic occlusion balloon with capnography and coronary and cerebral perfusion pressure (CPP) in the normothermic and traumatic-less cardiopulmonary arrest provoked by a ventricular fibrillation in pigs. This was an experimental study (cross-over study) in 14 pigs with similar characteristics (23 +/- 2 kg, 10-12 weeks of age). After an 8-minute nonintervention period, the cardiopulmonary resuscitation (CPR) consists of 4 periods of 5 minutes alternating CPR with and without intra-aortic occlusion balloon. Main outcomes measured are end-tidal CO(2) (ETCO(2)); intra-aortic, coronary, and cerebral perfusion pressures; blood gas analysis; and blood lactate concentration. At the end of each period, levels are obtained. Postmortem study was made. Inflation of the occlusion balloon provokes an expansion in the ETCO(2) of about 38%. The coronary perfusion pressure initially goes from 10.21 to 29.0 mm Hg after the occlusion of the aorta, which means an increase of 150%. The CPP goes from 12.54 to 39.71 mm Hg after the balloon was inflated, which means an increase of 200%. In all cases the differences are statistically significant (P <.0001). These increases are less important in the final periods. Intra-aortic balloon occlusion increased ETCO(2), coronary, and cerebral perfusion pressures. An early application of this technique was important.

[New aspects and perspectives on cardiac arrest]

OBJECTIVES

To analyse the current knowledge based on the experimental and the clinical research studies focused on the main fields of cardiopulmonary resuscitation.

DATA SOURCES

International guidelines and recent review articles. Data collected from the Medline database with the key word: cardiac arrest.

STUDY SELECTION

Research studies published during the last ten years were reviewed. Relevant clinical information was extracted and discussed when it induced changes in guidelines.

DATA SYNTHESIS

Promising improvements on basic and advanced life supports are proposed. Chest compressions prevail over ventilation. Alternatives to classical chest compressions are tested. Ventilatory volume must be reduced from 1000 to approximatively 500 mL for each breath with oxygen. Biphasic waveform defibrillators and automated external defibrillators will be considered as the best devices in the near future. Some non-catecholaminergic vasopressors could reduce the use of epinephrine for advanced cardiac life support. Lidocaine could be replaced by amiodarone as anti-arrhythmic drug of choice. New post-resuscitation therapeutic strategies are evaluated, especially coronary reperfusion when the cause of cardiac arrest is cardiac.

CONCLUSION

Many fields of cardiopulmonary resuscitation are investigated. Some relevant informations are included in the last international guidelines published in 2000, but most of them need complementary studies before other changes could be recommended for routine practice.

Intra-aortic administration of epinephrine above an aortic balloon occlusion during experimental CPR does not further improve cerebral blood flow and oxygenation

Balloon occlusion of the descending aorta during cardiopulmonary resuscitation (CPR) improves coronary and cerebral blood flow. In comparison with an equivalent dose administered through a central venous catheter it has been suggested that epinephrine administration above the aortic occlusion might produce a more rapid increase in coronary perfusion pressure and a shorter time to restoration of spontaneous circulation (ROSC). In a recent study, however, outcome was not improved after intra-aortic epinephrine administration. We hypothesised that epinephrine administered above the aortic occlusion could impose adverse effects on cerebral blood flow and oxygenation, possibly because of an alpha-adrenergic mediated vasoconstriction in the cerebral vascular beds. Twenty-six piglets underwent 5 min of non intervention cardiac arrest followed by 8 min of closed-chest CPR. They were randomised to receive bolus doses of 45 microg/kg epinephrine either above the aortic occlusion or through a central venous catheter. Cerebral cortical blood flow was continuously measured using laser-Doppler technique. Cerebral tissue pH and PCO(2) were also measured using a multi-parameter fiberoptic device and cerebral oxygen extraction was calculated. Balloon inflation resulted in an immediate enhancement of cerebral cortical blood flow. Each of the epinephrine boluses through the central venous catheter resulted in a transient increase in cerebral cortical blood flow. When administered above the aortic balloon occlusion, epinephrine did not result in a further increase in cerebral cortical blood flow, though a significant increase in cerebral perfusion pressure was recorded throughout the CPR period. Cerebral tissue pH monitoring revealed severe acidosis during CPR and long after ROSC, which was refractory to buffering. No differences in the cerebral oxygen extraction ratio were observed between the groups. In conclusion, epinephrine administration above an aortic balloon occlusion was unable to improve cerebral blood flow and oxygenation. In fact, it may even attenuate the beneficial effects of aortic balloon occlusion on cerebral blood flow due to an alpha-adrenergic mediated cerebral vasoconstriction. Further studies, including dose-response and volumes of distribution, are needed to identify the effective beneficial dosage of epinephrine during aortic occlusion with the least possible adverse effects.

Improved haemodynamics and restoration of spontaneous circulation with constant aortic occlusion during experimental cardiopulmonary resuscitation

Continuous balloon occlusion of the descending aorta is an experimental method that may improve blood flow to the myocardium and the brain during cardiopulmonary resuscitation (CPR). The aim of the present investigation was to evaluate the effects of this intervention on haemodynamics and the frequency of restoration of spontaneous circulation. Ventricular fibrillation was induced in 39 anaesthetised piglets, followed by an 8-min non-intervention interval. In a haemodynamic study (n = 10), closed chest CPR was performed for 7 min before the intra-aortic balloon was inflated. This intervention increased mean arterial blood pressure by 20%, reduced cardiac output by 33%, increased coronary artery blood flow by 86%, and increased common carotid artery blood flow by 62%. All these changes were statistically significant. Administration of epinephrine further increased mean arterial blood pressure and coronary artery blood flow, while cardiac output and common carotid artery blood flow decreased. In a study of short-term survival, nine out of 13 animals (69%) in the balloon group and in three out of 13 animals (23%) in the control group had spontaneous circulation restored. The difference between these two proportions was 0.46, which was statistically significant with a 95% confidence interval from 0.12 to 0.80. In conclusion, balloon occlusion of the descending aorta increased coronary and common carotid artery blood flow and the frequency of restoration of spontaneous circulation. It was also noted that epinephrine appears to augment the redistribution of blood flow caused by the aortic occlusion.