Closed-chest Cardiopulmonary Resuscitation Research Articles

Survival and neurologic outcomes following aortic occlusion for trauma and hemorrhagic shock in a hybrid operating room

BackgroundOutcomes following aortic occlusion for trauma and hemorrhagic shock are poor, leading some to question the clinical utility of aortic occlusion in this setting. This study evaluates neurologically intact survival following resuscitative endovascular balloon occlusion of the aorta (REBOA) versus resuscitative thoracotomy at a center with a dedicated trauma hybrid operating room with angiographic capabilities.MethodsThis retrospective cohort analysis compared patients who underwent zone 1 aortic occlusion via resuscitative thoracotomy (n = 13) versus REBOA (n = 13) for blunt or non-thoracic, penetrating trauma and refractory hemorrhagic shock (systolic blood pressure less than 90 mmHg despite volume resuscitation) at a level 1 trauma center with a dedicated trauma hybrid operating room. The primary outcome was survival to hospital discharge. The secondary outcome was neurologic status at hospital discharge, assessed by Glasgow Coma Scale (GCS) scores.ResultsOverall median age was 40 years, 27% had penetrating injuries, and 23% had pre-hospital closed-chest cardiopulmonary resuscitation. In both cohorts, median injury severity scores and head-abbreviated injury scores were 26 and 2, respectively. The resuscitative thoracotomy cohort had lower systolic blood pressure on arrival (0 [0–75] vs. 76 [65–99], p = 0.009). Hemorrhage control (systolic blood pressure 100 mmHg without ongoing vasopressor or transfusion requirements) was obtained in 77% of all REBOA cases and 8% of all resuscitative thoracotomy cases (p = 0.001). Survival to hospital discharge was greater in the REBOA cohort (54% vs. 8%, p = 0.030), as was discharge with GCS 15 (46% vs. 0%, p = 0.015).ConclusionsAmong patients undergoing aortic occlusion for blunt or non-thoracic, penetrating trauma and refractory hemorrhagic shock at a center with a dedicated, trauma hybrid operating room, nearly half of all patients managed with REBOA had neurologically intact survival. The high death rate in resuscitative thoracotomy and differences in patient cohorts limit direct comparison.

Retrospective study of gross and histopathologic lesions associated with closed chest cardiopulmonary resuscitation in dogs.

To investigate and characterise the incidence of iatrogenic complications secondary to closed chest cardiopulmonary resuscitation in dogs. Necropsy reports and histologic sections of tissues were retrospectively examined from 180 dogs that had received closed chest cardiopulmonary resuscitation to determine lesions associated with resuscitation. The most common complication was pulmonary haemorrhage (81/163, 49.7%, 95% confidence interval: 42.1 to 57.3), although only nine dogs had pulmonary haemorrhage of at least moderate severity. Liver fractures occurred in 16 of 180 cases (8.9%, 95% confidence interval: 5.5 to 14.0). Blood loss of >15% of blood volume into the abdomen and/or thorax occurred in 13 of 180 cases (7.2%, 95% confidence interval: 4.2 to 12.1). Significant haemorrhage secondary to cardiopulmonary resuscitation may decrease the chances of achieving the return of spontaneous circulation or may cause or compound ischemic damage to critical organs if the return of spontaneous circulation is achieved. Following successful cardiopulmonary resuscitation, animals should be screened for cavitary or pulmonary haemorrhage, as significant haemorrhage could be a factor in recurrence of cardiac arrest.

Open-chest versus closed-chest cardiopulmonary resuscitation in trauma patients with signs of life upon hospital arrival: a retrospective multicenter study

BackgroundThe effectiveness and indications of open-chest cardiopulmonary resuscitation (OCCPR) have been still debatable. Although current guidelines state that the presence of signs of life (SOL) is an indication for OCCPR, scientific evidence corroborating this recommendation has been scarce. This study aimed to compare the effectiveness of OCCPR to closed-chest cardiopulmonary resuscitation (CCCPR) in severe trauma patients with SOL upon arrival at the emergency department (ED).MethodsA retrospective cohort study analyzing data from the Trauma Quality Improvement Program (TQIP) database, a nationwide trauma registry in the USA, between 2010 and 2016 was conducted. Severe trauma patients who had SOL upon arrival at the hospital and received cardiopulmonary resuscitation within the first 6 h of ED admission were identified. Survival to hospital discharge was evaluated using logistic regression analysis, instrumental variable analysis, and propensity score matching analysis adjusting for potential confounders.ResultsA total of 2682 patients (OCCPR 1032; CCCPR 1650) were evaluated; of those 157 patients (15.2%) in the OCCPR group and 193 patients (11.7%) in the CCCPR group survived. OCCPR was significantly associated with higher survival to hospital discharge in both the logistic regression analysis (adjusted odds ratio [95% confidence interval] = 1.99 [1.42–2.79], p < 0.001) and the instrumental variable analysis (adjusted odds ratio [95% confidence interval] = 1.16 [1.02–1.31], p = 0.021). In the propensity score matching analysis, 531 matched pairs were generated, and the OCCPR group still showed significantly higher survival at hospital discharge (89 patients [16.8%] in the OCCPR group vs 58 patients [10.9%] in the CCCPR group; odds ratio [95% confidence interval] = 1.66 [1.13–2.42], p = 0.009).ConclusionsCompared to CCCPR, OCCPR was associated with significantly higher survival at hospital discharge in severe trauma patients with SOL upon ED arrival. Further studies to confirm these results and to assess long-term neurologic outcomes are needed.

Prospective Evaluation of Cardiopulmonary Resuscitation Performed in Dogs and Cats According to the RECOVER Guidelines. Part 2: Patient Outcomes and CPR Practice Since Guideline Implementation.

Cardiopulmonary resuscitation (CPR) outcomes have not been prospectively described since implementation of the Reassessment Campaign on Veterinary Resuscitation (RECOVER) guidelines. This study aimed to prospectively describe CPR outcomes and document arrest variables in dogs and cats at a U.S. veterinary teaching hospital since implementation of the RECOVER guidelines using the 2016 veterinary Utstein-style CPR reporting guidelines. One-hundred and seventy-two dogs and 47 cats that experienced cardiopulmonary arrest (CPA) underwent CPR following implementation of the RECOVER guidelines and were prospectively included. Supervising clinicians completed a data form for CPR events immediately following completion of CPR from December 2013 to June 2018. Seventy-five (44%) dogs and 26 (55%) cats attained return of spontaneous circulation (ROSC), 45 dogs (26%) and 16 cats (34%) had ROSC ≥ 20 min, 13 dogs (8%) and 10 cats (21%) were alive 24 h after CPR, and 12 dogs (7%) and 9 cats (19%) survived to hospital discharge. The most common cause of death in animals with ROSC ≥ 20 min was euthanasia. Patient outcomes were not significantly different since publication of the RECOVER guidelines except for a higher feline survival to hospital discharge rate. Dogs (p = 0.02) but not cats with initial shockable rhythms had increased rates of ROSC while the development of a shockable rhythm during CPR efforts was not associated with ROSC (p = 0.30). In closed chest CPR an end-tidal carbon dioxide (EtCO2) value of >16.5 mmHg was associated with a 75% sensitivity and 64% specificity for achieving ROSC. Since publication of the RECOVER guidelines, CPR practice did not clinically significantly change at our institution and no improvement of already high ROSC rates was noted. The percentage of cats surviving to hospital discharge was higher than previously reported and the reason for this improvement is not evident with these results. Euthanasia remains a major confounding factor in assessing intermediate and long-term CPR outcomes in dogs and cats.

Forensic Aspects of Probable Life-Threatening Complications of Closed Chest Cardiopulmonary Resuscitation in Non-Traumatic Patients

Cardiopulmonary resuscitation (CPR)is a life-saving procedure that can also cause many life-threatening injuries to patients. The complications that can arise from the application of CPR are confronted by the existing legal system as a medical error and since forensic pathologists often encounter various types of CPR-related injuries during autopsies, they must be able to distinguish between CPR-related injuries and those caused by other factors. The aim of the present study was to analyze the findings of autopsy reports of patients who received CPR to determine the frequency of its related life-threatening injuries and to determine the possible factors that affect and increase the risk of these injuries. The study included 58 non-traumatic death cases that had undergone CPR and CPR-related injuries were determined based on X ray CT interpretation reports. The results concluded that the advanced life support was provided in the vast majority of cases (70.7%). The mean duration of CPR provided was (22.0 ± 12.35 & 21.5 ± 13.56 min.) in males and females respectively and defibrillation procedure took place in 79.3% of cases.The most common complications detected were the thoracic cage complications where the costal injuries were the most frequent complications in 48.4% of cases, mid-clavicular rib fracture was the most frequent one and 66.7% of sternal fractures were detected at the level of the third rib. Males were more susceptible to rib and sternal fractures than females. The factors of age, gender and CPR duration were found to have an effect on the increased risk of life-threatening injuries. The risk of injury increases especially when the compression depth exceeded 6 cm. and CPR duration exceeds 30 min. The present study concluded that CPR complications may decrease the patient’s chance of survival and can cause death by itself. The present study recommend detailed post-mortem studies on CPR related life-threatening injuries on a trial of their prevention.

Open-chest versus closed-chest cardiopulmonary resuscitation in blunt trauma: analysis of a nationwide trauma registry

BackgroundAlthough open-chest cardiopulmonary resuscitation (OCCPR) is often considered as the last salvage maneuver in critically injured patients, evidence on the effectiveness of OCCPR has been based only on the descriptive studies of limited numbers of cases or expert opinions. This study aimed to compare the effectiveness of OCCPR with that of closed-chest cardiopulmonary resuscitation (CCCPR) in an emergency department (ED).MethodsA nationwide registry-based, retrospective cohort study was conducted. Patients with blunt trauma, undergoing cardiopulmonary resuscitation (CPR) in an ED between 2004 and 2015 were identified and divided into OCCPR and CCCPR groups. Their outcomes (survival to hospital discharge and survival over 24 hours following ED arrival) were compared with propensity score matching analysis and instrumental variable analysis.ResultsA total of 6510 patients (OCCPR, 2192; CCCPR, 4318) were analyzed. The in-hospital and 24-hour survival rates in OCCPR patients were 1.8% (40/2192) and 5.6% (123/2192), and those in CCCPR patients were 3.6% (156/4318) and 9.6% (416/4318), respectively. In the propensity score-matched subjects, OCCPR patients (n = 1804) had significantly lower odds of survival to hospital discharge (odds ratio (95% CI)) = 0.41 (0.25–0.68)) and of survival over 24 hours following ED arrival (OR (95% CI) = 0.59 (0.45–0.79)) than CCCPR patients (n = 1804). Subgroup analysis revealed that OCCPR was associated with a poorer outcome compared to CCCPR in patients with severe pelvis and lower extremity injury.ConclusionsIn this large cohort, OCCPR was associated with reduced in-hospital and 24-hour survival rates in patients with blunt trauma. Further comparisons between OCCPR and CCCPR using additional information, such as time course details in pre-hospital and ED settings, anatomical details regarding region of injury, and neurological outcomes, are necessary.

“Do-not-resuscitate orders: a clinical ethics perspective” medicolegal and bioethics

Closed chest cardiopulmonary resuscitation (CPR), having been so successful after its introduction in the operating room for saving lives of anesthetized patients, was adopted for use in the intensive care units, then hospital-wide, and finally to out of hospital patients. This has lead to ethical dilemmas involving patients who must themselves request discontinuation of artificial organ function devices and treatments, or placing family members in the difficult positions of having to make those decisions for their unconscious and suffering relatives. In this review, the Ethical principles on which physicians, hospitals, patients, and surrogate decision makers rely in order to apply their perceived moral obligations to provide patient safety, comfort, and treatment are examined with particular emphasis on do not resuscitate orders (DNR). It is clear that DNR does not equate with do not treat.

Irrational Exuberance: Cardiopulmonary Resuscitation as Fetish

The Institute of Medicine and the American Heart Association have issued a “call to action” to expand the performance of cardiopulmonary resuscitation (CPR) in response to out-of-hospital cardiac arrest. Widespread advertising campaigns have been created to encourage more members of the lay public to undergo training in the technique of closed-chest compression-only CPR, based upon extolling the virtues of rapid initiation of resuscitation, untempered by information about the often distressing outcomes, and hailing the “improved” results when nonprofessional bystanders are involved. We describe this misrepresentation of CPR as a highly effective treatment as the fetishization of this valuable, but often inappropriately used, therapy. We propose that the medical profession has an ethical duty to inform the public through education campaigns about the procedure's limitations in the out-of-hospital setting and the narrow clinical indications for which it has been demonstrated to have a reasonable probability of producing favorable outcomes.

Clinical Ethics of the Do-Not-Resuscitate (DNR) Order and Other Advanced Directives in Anesthesia and ICU

Closed chest cardiopulmonary resuscitation (CPR), having been so successful after its introduction in the operating room for saving lives of anesthetized patients, was adopted for use in the intensive care units, then hospital-wide, and finally to out of hospital patients. This has lead to ethical dilemmas involving patients who must themselves request discontinuation of artificial organ function devices and treatments, or placing family members in the difficult positions of having to make those decisions for their unconscious and suffering relatives. In this review, the Ethical principles on which physicians, hospitals, patients, and surrogate decision makers rely in order to apply their perceived moral obligations to provide patient safety, comfort, and treatment are examined with particular emphasis on do not resuscitate orders (DNR). It is clear that DNR does not equate with do not treat.

Measured Progress in Cardiopulmonary Resuscitation.

> “…inspiration is easy. Implementation is the hard part.” > > –Bob Taylor, Taylor Guitars Eight months after Kouwenhoven et al1 published their 1960 landmark report of successful closed chest cardiac compressions for 2 children and 2 adults who developed perioperative cardiac arrest,1 a cardiologist provided that same closed chest cardiopulmonary resuscitation (CPR) in the operating suite after my 4-year-old brother experienced cardiac arrest during induction of anesthesia. My brother is alive today because of published resuscitation science applied to practice. In 1961, Peter Safar proposed combining mouth-to-mouth ventilation with closed chest compressions in a poster for the Pennsylvania chapter of the American Heart Association (AHA), and the ABCs of CPR were born. In 1966, the National Academy of Sciences–National Research Council conference on CPR charged the AHA with teaching CPR to healthcare providers. In 1973, the second conference on CPR and Emergency Cardiovascular Care recommended expanding teaching of CPR to the lay public. This conference also recommended that the AHA establish resuscitation guidelines based on scientific data and develop standards for basic and advanced life support training. The American Red Cross and other organizations, such as the Citizen CPR Foundation, soon supported the lay rescuer CPR training effort. Great enthusiasm existed for the potential of CPR, but little scientific data on which to base recommendations, with more emphasis on teaching CPR skills than on measuring CPR outcomes. By 1991, the chain of survival provided a metaphor for the priorities of resuscitation and training, emphasizing early bystander recognition of cardiac arrest and access to the emergency medical …

Outcome of patients receiving CPR in the ED of an urban academic hospital

BackgroundThe success of Closed Chest Cardiopulmonary Resuscitation (CC-CPR) degrades with prolonged times. Open Chest CPR (OC-CPR) is an alternative that may lead to superior coronary and cerebral perfusion. It is critical to determine when continued CC-CPR is unlikely to be successful to justify initiating OC-CPR as rescue therapy. The purpose of this study is to review CC-CPR outcomes to define a time threshold for attempting OC-CPR. MethodsWe identified all adult non-trauma patients diagnosed with cardiac arrest, ventricular fibrillation, ventricular tachycardia and asystole from 1/1/10-12/31/14. We collected demographics, cardiac rhythm, resuscitation duration, survival to hospital discharge and neurological outcome. Using time to ROSC after ED arrival and good neurological outcome, we explored various times as triggers for attempting OC-CPR. ResultsAmong 242 cases of CPR, 205 cases were out-of-hospital cardiac arrest (OHCA). Mean age was 63.7 (±16.9),woman comprised 29.8% (72/242), and median prehospital CPR time was 30 min (20-44). Patients suffering ED arrest had improved ROSC (54.1% vs. 12.7%, p<0.001) and survival to hospital discharge rates (37.8% vs. 2.9%, p<0.001) compared to OHCA. Patients achieving ROSC had median total CPR duration of 18 minutes (10 minutes of pre-hospital CPR) compared with patients without ROSC who had 45 minutes (30 pre-hospital) respectively. No patient receiving > 10 minutes of CPR in the ED survived to hospital discharge. ConclusionIn patients suffering OHCA and requiring CC-CPR in the ED, overall survival rate to good neurologic function is low. OC-CPR could potentially be attempted after 10 minutes of CC-CPR in the ED.

The Physiology of Cardiopulmonary Resuscitation.

Outcomes after cardiac arrest remain poor more than a half a century after closed chest cardiopulmonary resuscitation (CPR) was first described. This review article is focused on recent insights into the physiology of blood flow to the heart and brain during CPR. Over the past 20 years, a greater understanding of heart-brain-lung interactions has resulted in novel resuscitation methods and technologies that significantly improve outcomes from cardiac arrest. This article highlights the importance of attention to CPR quality, recent approaches to regulate intrathoracic pressure to improve cerebral and systemic perfusion, and ongoing research related to the ways to mitigate reperfusion injury during CPR. Taken together, these new approaches in adult and pediatric patients provide an innovative, physiologically based road map to increase survival and quality of life after cardiac arrest.

The effectiveness of prophylactic attachment of adhesive defibrillation pads in adult living donor liver transplantation.

The aim of current study is to present the effectiveness of prophylactic attachment of adhesive defibrillation electrode pads in adult living donor liver transplantation. We divided 487 adult living donor liver transplantation patients into 2 Eras according to the history of without (Era 1) and with (Era 2) pre-attachment of adhesive defibrillation pads. The incidences of intraoperative cardiac events requiring cardioversion or defibrillation, its management, and outcome between Era 1 and 2 were compared. Two cases out of 124 patients (1.6%) in Era 1 had cardiac arrest. The closed chest cardiac massage in 1 cardiac arrest in Era 1 required trans-diaphragmatic open-chest cardiac massage followed by internal cardiac defibrillation due to difficulty in performing external defibrillation. Both patients of Era 1 had in-hospital mortality. Four patients of Era 2 (n=363) received electrical treatment (1.01%); 2 had paroxysmal tachycardia requiring cardio-version and the other 2 had ventricular fibrillation requiring closed-chest cardiac massage and external defibrillation. All 4 patients in Era 2 regained sinus rhythm after electrical treatment, tolerated the subsequent operation well, and had 100% survival to date. Our results show that prophylactic attachment of adhesive defibrillation pads allows the immediate performance of cardioversion, conventional closed-chest CPR, and defibrillation if indicated without any delay and without interference with the sterility of the operation field. Our preliminary result is clear and encouraging.

Feasibility of blind aortic catheter placement in the prehospital environment to guide resuscitation in cardiac arrest

Aortic catheter-based resuscitation therapies are emerging with laboratory investigations showing benefit in models of trauma-related noncompressible torso hemorrhage and nontraumatic cardiac arrest. For these investigational aortic catheter-based therapies to reach their greatest potential clinical benefit, the ability to initiate them in the prehospital setting will be important. Feasibility of prehospital aortic catheterization without imaging capability supports this potential and is described in this report. A physician prehospital response system was created in cooperation with the local emergency medical services system to provide invasive hemodynamic monitoring during cardiac arrest. Physicians were dispatched to all known or suspected prehospital cardiac arrests covered by the emergency medical services system. Physicians responded with a specialized vascular catheterization pack and a monitor with invasive pressure monitoring capability. The physicians performed blind thoracic aortic and central venous catheterizations in cardiac arrest patients in the prehospital setting to measure coronary perfusion pressure, to optimize closed-chest cardiopulmonary resuscitation technique, and to administer intra-aortic epinephrine. During a 2-year period, 22 medical cardiac arrest patients underwent prehospital invasive hemodynamic monitoring to guide resuscitation. Most patients had both aortic and central venous catheters inserted. The combination of intra-aortic epinephrine and adjustments in closed-chest cardiopulmonary resuscitation technique resulted in improved coronary perfusion pressure. Return of spontaneous circulation with survival to hospital admission was achieved in 50% (11 of 22) of these patients. This report demonstrates the feasibility of successful blind aortic and central venous catheterizations in the prehospital environment and supports the potential feasibility of other emerging aortic catheter-based resuscitation therapies.

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Case Reports: A 57 year old male underwent routine off-pump coronary artery bypass surgery for multivessel coronary artery disease. Approximately 45 minutes after intensive care unit (ICU) admission, he developed pulseless ventricular tachycardia, for which advanced cardiovascular life support was initiated. Cardiopulmonary resuscitation (CPR) included closed chest compressions. The cardiac rhythm varied between ventricular tachycardia, idioventricular, and asystole. Multiple doses of epinephrine were given with return of spontaneous circulation after 15 minutes of CPR. Massive chest tube drainage followed by profound hypotension unresponsive to vasopressors prompted emergent re-sternotomy in the ICU. A right ventricle (RV) laceration was noted and manual pressure was applied to control hemorrhage. The patient was immediately returned to the operating room for emergent mediastinal re-exploration. The RV laceration was repaired primarily and he was subsequently placed on cardiopulmonary bypass. Careful inspection of the bypass grafts revealed thrombosis of the obtuse marginal vein graft. The obtuse marginal was re-grafted with saphenous vein distal to the previous graft. No other significant bleeding sources were identified, hemostasis was achieved, and the chest was closed. The patient recovered uneventfully and was discharged on the 10th postoperative day. Discussion: Cardiac arrest secondary to ventricular dysrhythmias was caused by saphenous vein graft occlusion to the lateral wall. Cardiac compression, via a closed or open chest technique, was necessary in restoring circulation. RV laceration is a very rare mechanical event occurring as a consequence of closed chest CPR after recent sternotomy. A high level of suspicion is required if increased bleeding is noted during CPR. Prompt chest re-exploration during or after CPR for cardiac surgery patients can be a lifesaving intervention in appropriately selected patients.

Characteristics of hemodynamics during closed chest cardiopulmonary resuscitation

Objective To study the hemodynamics during closed chest cardiopulmonary resuscitation (CCCPR) in dogs in order to unravel the mechanism. Method Twelve healthy mongrel dogs were selected to make animal model of ventricular fibrillation induced by electric shock on the chest wall. Closed-chest cardiopulmonary resuscitation (CCCPR) was initiated four minutes after ventricular fibrillation appeared according to American Heart Guidelines in 2005 for Cardiopulmonary Resuscitation and Emergency Cardiovascular Rescue. After CPR for 2 minutes, 1mg epinephrine was injected intravenously. The central venous pressure (CVP), the aortic pressure (AOP)and the invasive electrocardiogram (ECG) were used to monitor continuously before ventricular fibrillation and the entire course of CPR. The coronary perfusion pressure (CPP) was calculated. The changes in aortic diastolic pressure (ADP) and CPP produced by chest compression or the injection of epinephrine were analyzed. The aortic pressure and the central venous pressure were recorded simultaneously during CPR. A chart was made and the CPP was calculated with the software Chart5Ch. The hemodynamic changes produced by the administration of epinephrine were studied. Data were analyzed with paired Student t test. P ＜ 0.05 was considered as a significant difference. Results Two kinds of hemodynamic effects of CPR were observed. In 8 dogs (8/12) , the aortic pressure changed synchronously with the CVP, and the CPP was almost zero, and in other 4 dogs (4/12), the aortic pressure increased and the CVP remained unchanged with presence of the CPP. After the administration of epinephrine, the AOP and the CPP increased significantly. The Aortic systolic pressure(ASP) increased from (66± 14) mmHg to(107 ± 28) mmHg, (P = 0. 001). The Aortic diastolic pressure (ADP) increased from (25 ±2.2) mmHg to(45 ± 13) mmHg (P =0.001). And the coronary perfusion pressure (CPP) increased from (2.8± 3.8) mmHg to (29 ± 13) mmHg (P ＜ 0.001). The 95 % confidential interval of the added value of the ASP,ADP and CPPwere (21.1-59.1), (10.2-28.3) and (16.7-35.7), respectively. Conclusions The thoracic pump mechanism is the primary role in the closed chest Cardiopulmonary resuscitation. Epinephrine can increase ADP and CPP and has the capability to break the balance between aortic pressure and central venous pressure, increasing the rate of successful cardiopulmonary resuscitation. Key words: Cardiopulmonary resuscitation; Closed chest; Hemodynamics; Epinephrine; Mechanism

Methods for Calculating Coronary Perfusion Pressure During CPR

Coronary perfusion pressure (CPP) is a major indicator of the effectiveness of cardiopulmonary resuscitation in human and animal research studies, however, methods for calculating CPP differ among research groups. Here we compare the 6 published methods for calculating CPP using the same data set of aortic (Ao) and right atrial (RA) blood pressures. CPP was computed using each of the 6 calculation methods in an anesthetized pig model, instrumented with catheters with Cobe pressure transducers. Aortic and right atrial pressures were recorded continuously during electrically induced ventricular fibrillation and standard AHA CPR. CPP calculated from the same raw data set by the 6 calculation methods ranged from -1 (signifying retrograde blood flow) to 26 mmHg (mean +/- SD of 15 +/- 11 mmHg). The CPP achieved by standard closed chest CPR is typically reported as 10-20 mmHg. Within a single study the CPP values may be comparable; however, the CPP values for different studies may not be a reliable indicator of the efficacy of a given CPR method. Electronically derived true mean coronary perfusion pressure is arguably the gold standard method for representing coronary perfusion pressure.

Cerebral metabolic rate of oxygen (CMRO 2) in pig brain determined by PET after resuscitation from cardiac arrest

Aim To assess the regional vulnerability to ischemic damage and perfusion/metabolism mismatch of reperfused brain following restoration of spontaneous circulation (ROSC) after cardiac arrest. Method We used positron emission tomography (PET) to map cerebral metabolic rate of oxygen (CMRO 2), cerebral blood flow (CBF) and oxygen extraction fraction (OEF) in brain of young pigs at intervals after resuscitation from cardiac arrest. After obtaining baseline PET recordings, ventricular fibrillation of 10 min duration was induced, followed by mechanical closed-chest cardiopulmonary resuscitation (CPR) in conjunction with i.v. administration of 0.4 U/kg of vasopressin. After CPR, external defibrillatory shocks were applied to achieve restoration of spontaneous circulation (ROSC). CBF and CMRO 2 were mapped and voxelwise maps of OEF were calculated at times of 60, 180, and 300 min after ROSC. Results There was hypoperfusion throughout the telencephalon at 60 min, with a return towards baseline values at 300 min. In contrast, there was progressively increasing CBF in cerebellum throughout the observation period. The magnitude of CMRO 2 decreased globally after ROSC, especially in cerebral cortex. The magnitude of OEF in cerebral cortex was 60% at baseline, tended to increase at 60 min after ROSC, and declined to 50% thereafter, thus suggesting transition to an ischemic state. Conclusion The cortical regions tended most vulnerable to the ischemic insult with an oligaemic pattern and a low CMRO 2 whereas the cerebellum instead showed a pattern of luxury perfusion.

Progress in Resuscitation

THERE WAS A TIME NOT LONG AGO WHEN THE QUALity and quantity of chest compressions did not seem that important during resuscitation—at least not in comparison with early defibrillation. A ventricular tachyarrhythmia is the initiating event in more than 80% of patients who develop out-of-hospital, primary cardiac arrest during ambulatory electrocardiographic monitoring. Survival declines rapidly if defibrillation is not performed in the first few minutes (defibrillation phase) because myocardial adenosine triphosphate (ATP) levels begin to decrease as fibrillating myocardial cells continue to consume ATP at a nearly normal rate. As a result, ventricular fibrillation (VF) is the presenting rhythm in only 22% to 35% of out-of-hospital cardiac arrest cases when emergency medical services (EMS) personnel arrive on scene. By this time, myocardial ATP stores have often declined to critical levels and a defibrillation shock will usually terminate VF but frequently results in either asystole or pulseless electrical activity as cells run out of high-energy phosphate “fuel.” During this circulatory phase, a brief period of effective chest compression before defibrillation can boost myocardial ATP stores and increase the likelihood that a perfusing rhythm will follow defibrillation. Thus, the strategy for resuscitation from cardiac arrest has evolved from “shock first and often” to a time-critical, orchestrated approach of high-quality cardiopulmonary resuscitation (CPR), defibrillation, and postresuscitation care. This new approach highlights the importance of highquality, minimally interrupted chest compressions to maximize tissue oxygen delivery and intracellular high-energy phosphate levels. Conventional, closed-chest CPR is at best imperfect, producing hemodynamic change similar to that observed in cardiogenic shock. Minimal interruption of chest compression helps to maximize tissue oxygen delivery and, hence, myocardial high-energy phosphate levels. Aufderheide et al showed that both high-quality chest compression (adequate depth, force, and duration) and complete chest wall decompression are needed to maximize stroke volume and improve venous filling during the upstroke, respectively. The odds of survival from cardiac arrest increase when continuous, or nearly continuous, high-quality chest compressions are performed during resuscitation. Abella et al used a monitor/defibrillator with additional sensing capabilities to measure CPR quality (chest compression rate and depth, ventilation rate, and the fraction of cardiac arrest time without chest compressions) during resuscitation in 67 patients who experienced in-hospital cardiac arrest. The authors found that the quality of chest compression was inconsistent and often did not meet published guideline recommendations, even when performed by well-trained hospital staff. In a follow-up study, the same authors used a handheld recording device to measure chest compression rate as a surrogate for CPR quality in 3 different hospitals and found that higher chest compression rates correlated significantly with initial return of spontaneous circulation in 97 in-hospital patients with cardiac arrest. Thus, chest compression quantity and quality are critical determinants of survival from cardiac arrest. Positive pressure ventilation may not be necessary during the first few minutes of CPR because spontaneous agonal respirations often contribute to respiratory exchange of gases. Chest compression alone with a patent airway generates significant minute ventilation and the quantity of oxygen needed is reduced significantly during low blood flow states. Chandra et al assessed the time course of change in arterial blood gases during resuscitation in a canine experimental VF model and found that chest compression alone during CPR can maintain adequate gas exchange to sustain the oxygen saturation level above 90% for at least 4 minutes. Survival from out-of-hospital cardiac arrest is as good in humans when bystanders perform only chest compressions compared with when bystanders perform both chest compressions and mouth-to-mouth ventilation. In this issue of JAMA, Bobrow and colleagues provide an analysis based on a before and after comparison as well as a protocol compliance analysis of out-of-hospital

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

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