Genomes of Novel Myxococcota Reveal Severely Curtailed Machineries for Predation and Cellular Differentiation.

Cultured Myxococcota are predominantly aerobic soil inhabitants, characterized by their highly coordinated predation and cellular differentiation capacities. Little is currently known regarding yet-uncultured Myxococcota from anaerobic, nonsoil habitats. We analyzed genomes representing one novel order (o__JAFGXQ01) and one novel family (f__JAFGIB01) in the Myxococcota from an anoxic freshwater spring (Zodletone Spring) in Oklahoma, USA. Compared to their soil counterparts, anaerobic Myxococcota possess smaller genomes and a smaller number of genes encoding biosynthetic gene clusters (BGCs), peptidases, one- and two-component signal transduction systems, and transcriptional regulators. Detailed analysis of 13 distinct pathways/processes crucial to predation and cellular differentiation revealed severely curtailed machineries, with the notable absence of homologs for key transcription factors (e.g., FruA and MrpC), outer membrane exchange receptor (TraA), and the majority of sporulation-specific and A-motility-specific genes. Further, machine learning approaches based on a set of 634 genes informative of social lifestyle predicted a nonsocial behavior for Zodletone Myxococcota. Metabolically, Zodletone Myxococcota genomes lacked aerobic respiratory capacities but carried genes suggestive of fermentation, dissimilatory nitrite reduction, and dissimilatory sulfate-reduction (in f_JAFGIB01) for energy acquisition. We propose that predation and cellular differentiation represent a niche adaptation strategy that evolved circa 500 million years ago (Mya) in response to the rise of soil as a distinct habitat on Earth. IMPORTANCE The phylum Myxococcota is a phylogenetically coherent bacterial lineage that exhibits unique social traits. Cultured Myxococcota are predominantly aerobic soil-dwelling microorganisms that are capable of predation and fruiting body formation. However, multiple yet-uncultured lineages within the Myxococcota have been encountered in a wide range of nonsoil, predominantly anaerobic habitats, and the metabolic capabilities, physiological preferences, and capacity of social behavior of such lineages remain unclear. Here, we analyzed genomes recovered from a metagenomic analysis of an anoxic freshwater spring in Oklahoma, USA, that represent novel, yet-uncultured, orders and families in the Myxococcota. The genomes appear to lack the characteristic hallmarks for social behavior encountered in Myxococcota genomes and displayed a significantly smaller genome size and a smaller number of genes encoding biosynthetic gene clusters, peptidases, signal transduction systems, and transcriptional regulators. Such perceived lack of social capacity was confirmed through detailed comparative genomic analysis of 13 pathways associated with Myxococcota social behavior, as well as the implementation of machine learning approaches to predict social behavior based on genome composition. Metabolically, these novel Myxococcota are predicted to be strict anaerobes, utilizing fermentation, nitrate reduction, and dissimilarity sulfate reduction for energy acquisition. Our results highlight the broad patterns of metabolic diversity within the yet-uncultured Myxococcota and suggest that the evolution of predation and fruiting body formation in the Myxococcota has occurred in response to soil formation as a distinct habitat on Earth.

Brain resuscitation.

Optimal neurological outcome after cardiac arrest requires careful attention to the details of both intracranial and extracranial homeostasis. A high index of suspicion regarding the potential causes and complications of cardiac arrest facilitates discovery and treatment of problems before they adversely impact upon neurological outcome. The future is bright for resuscitation research since our fundamental understanding of cerebral ischemia and its consequences has dramatically improved. This knowledge can hopefully be transferred to clinical useful modes of therapy.

Quality of bystander cardiopulmonary resuscitation influences outcome after prehospital cardiac arrest.

To evaluate the influence of quality of bystander cardiopulmonary resuscitation (CPR) on outcome in prehospital cardiac arrest we consecutively included patients with prehospital cardiac arrest treated by paramedics in a community run ambulance system in Oslo, Norway from 1985 to 1989. Good CPR was defined as palpable carotid or femoral pulse and intermittent chest expansion with inflation attempts. Outcome measure was hospital discharge rate. One hundred and forty-nine of 334 patients (45%) received bystander CPR. The discharge rate after good BCPR (23%) was higher than after no good BCPR (1%, P < 0.0005) or after no BCPR (6%, P < 0.0005). There was no difference between no good and no BCPR (P = 0.1114). There were no differences in paramedic response interval between the groups, but the mean interval from start of unconsciousness to initiation of CPR (arrest-CPR interval) was significantly shorter in the group receiving good bystander CPR (2.5 min, 95% confidence interval (CI): 1.7-3.3 min) than no good CPR (6.6 min, CI: 5.2-8.0 min) or no bystander CPR (7.8 min, CI: 7.2-8.4 min). Bystanders started CPR more frequently in public than in the patient's home (58 vs. 34%, P < 0.0005). Good bystander CPR was associated with a shorter arrest-CPR interval and improved hospital discharge rate as compared to no good BCPR or no BCPR.

A comparison of prolonged manual and mechanical external chest compression after cardiac arrest in dogs.

The effects of manual and a new mechanical chest compression device (Heartsaver 2000) during prolonged CPR with respect to haemodynamics and outcome were tested in a prospective, randomized, controlled experimental trial during ventricular fibrillation in 12 dogs of 9-13 kg body weight after 1 min of cardiac arrest. During the first 10 min of CPR the dogs were resuscitated according to the Basic Life Support (BLS) algorithm, followed by 20 min of Advanced Life Support (ALS) algorithm. After 30 min of CPR both manual and mechanical CPR groups were resuscitated following a standardized ALS protocol. During CPR, coronary perfusion pressure and end tidal CO2 were greater with mechanical CPR. All animals were successfully resuscitated and neurological deficit scores were not different. The CPR trauma score was less in the mechanical group. Mechanical external chest compression provided better haemodynamics than the manual technique, though outcome did not differ. Both optimally performed manual and mechanical techniques produce flow sufficient to maintain organ viability for 30 min of CPR after a 1 min arrest interval.

ATP-MgCl2 pre-treatment in an animal model of asphyxial arrest.

ATP-MgCl2 treatment has been found to be a promising intervention in many models of hypoxic/ischemic injury. In this study, the effect of pre-treatment with ATP-MgCl2 on the hemodynamic response to asphyxia in the rat was examined. Rats were anesthetized with halothane and N2O2. A tracheostomy and femoral artery and vein cutdowns were performed. Rats were infused intravenously with either ATP-MgCl2 (approximately 50 mumol/kg) or normal saline (control group) over 15 min. Animals were then asphyxiated for 8 min by occlusion of the ventilator tubing. Following the asphyxia, 1 min of cardiopulmonary resuscitation (CPR) was attempted. Heart rate and blood pressure were monitored continuously throughout the experiment. A total of 41 animals (21 ATP-MgCl2, 20 control) were studied. Analysis of variance (ANOVA) was used to test for differences between groups. The ATP-MgCl2 group had a lower heart rate (HR) and mean arterial pressure (MAP) during the infusion. During asphyxia the ATP-MgCl2 group had a lower MAP but higher HR when compared to the control group. No significant differences were observed in the rates of successful resuscitation between ATP-MgCl2-treated rats (10 of 21, 48%) and controls (12 of 20, 60%). Possible reasons for the apparent lack of benefit of ATP-MgCl2 therapy are discussed.

CPR training without an instructor: development and evaluation of a video self-instructional system for effective performance of cardiopulmonary resuscitation.

Traditional classroom-based instruction of cardiopulmonary resuscitation (CPR) has failed to achieve desired rates of bystander CPR. Video self-instruction (VSI) is a more accessible alternative to traditional classroom instruction (TRAD), and it achieves better CPR skill performance. VSI employs a 34-min training tape and an inexpensive manikin. VSI combines simplified and reordered content focusing on the delivery of one-rescuer CPR with the 'practice-as-you-watch' approach of an exercise video. Performance of CPR skills immediately following VSI was compared to performance immediately following TRAD using an instrumented manikin, a valid and reliable skill checklist, and an overall competency rating. Compared with TRAD subjects, VSI subjects performed more compressions correctly (P < 0.001), more ventilations correctly (P < 0.001), and more assessment and sequence skills correctly (P < 0.001). TRAD subjects delivered twice as many compressions that were too shallow, and underinflated the lungs twice as often. VSI subjects were rated 'competent' or better 80.0% of the time, compared with TRAD subjects, who achieved this rating only 45.1% of the time (P < 0.001). TRAD subjects were rated to be 'not competent' in performing CPR nearly 10 times more often than VSI subjects (P < 0.001). Subjects 40 years of age and older performed better after VSI than after TRAD. Superior skill performance among subjects exposed to VSI persisted 60 days following training. VSI has the potential to reach individuals unlikely to participate in TRAD classes because of its greater convenience, lower cost, and training in about 0.50 h compared with 3-4 h for TRAD classes.

Intra-aortic administration of epinephrine above aortic occlusion does not alter outcome of experimental cardiopulmonary resuscitation.

Intra-aortic balloon occlusion during experimental cardiopulmonary resuscitation (CPR) improves coronary perfusion pressure and resuscitability and provides unique access to the central circulation. It has been hypothesized that administration of epinephrine into the aortic arch in combination with aortic occlusion would further improve haemodynamics during CPR, resuscitability and 24 h survival. In 16 anaesthetised dogs intravascular catheters were placed for hemodynamic and blood gas monitoring. An aortic balloon catheter was placed by femoral artery insertion with its tip just distal to the left subclavian artery. Ventricular fibrillation for 7.5 min without CPR, 2.5 min of Basic Life Support with chest compressions and ventilation with 100% oxygen were followed by 30 min of Advanced Cardiac Life Support (ACLS) with systemic canine drug dosages. The intra-aortic balloon was inflated when ACLS started and gradually deflated shortly after restoration of spontaneous circulation (ROSC). Epinephrine, in 100 microg/kg boluses every 5 min until the heart was restarted or 30 min had elapsed was administered through the intra-aortic catheter in the experimental group (n = 8) and via a central venous catheter in the control group (n = 8). Coronary perfusion pressure increased during the ACLS period in both groups (P < 0.05) with no difference between the groups and there was no difference in the frequency of ROSC (experimental group 5/8, control group 4/8). Furthermore with respect to 24 h survival, there was no difference between the experimental group (2/8) and the control group (3/8). Severe macroscopic haemorrhagic necrosis of the myocardium in the dogs with ROSC was found in 4/5 in the experimental group compared to 1/4 in the control group. In conclusion, intra-aortic administration of 100 microg/kg epinephrine doses combined with aortic occlusion during experimental CPR did not alter outcome.

Epinephrine and sodium bicarbonate during CPR following asphyxial cardiac arrest in rats.

Although high-dose epinephrine during CPR improves coronary perfusion pressure (CoPP) and rate of return of spontaneous circulation (ROSC) in some models, its impact on long term outcome (> or = 72 h) has not been evaluated. Previous studies of sodium bicarbonate (NaHCO3) therapy during CPR indicate that beneficial effects may be dependent on epinephrine (EPI) dose. We hypothesized that EPI and NaHCO3 given during CPR have a significant impact on long term outcome. One hundred male Sprague-Dawley rats were prospectively studied in a block randomized placebo controlled trial. Rats were anesthetized, paralyzed, mechanically ventilated, instrumented, and each underwent 10 min of asphyxia, resulting in 6.8 +/- 0.4 min of circulatory arrest. Resuscitation was performed by mechanical ventilation and manual external chest compressions. EPI 0.0 (placebo), 0.01, 0.1, or 1.0 mg/kg IV was given at the onset of CPR, followed by NaHCO3 0.0 (placebo) or 1.0 mEq/kg IV. Successfully resuscitated rats were monitored and ventilated for 1 h without hemodynamic support. Neurologic deficit scores (NDS), cerebral histopathologic damage scores (CHDS) and myocardial histopathologic damage scores (MHDS) were determined in rats that survived 72 h. EPI improved CoPP and ROSC in a dose-dependent manner up to 0.1 mg/kg. Rats receiving EPI 0.1 and 1.0 mg/kg during CPR exhibited prolonged post-ROSC hypertension and metabolic acidemia, increased A-a O2 gradient, and an increased incidence of post-ROSC ventricular tachycardia or fibrillation. Overall survival was lower with EPI 0.1 and 1.0 mg/kg compared to 0.01 mg/kg. Although NDS was significantly less with EPI 0.1 mg/kg compared to placebo, there was no difference in CHDS between groups. In contrast, MDS was significantly higher with EPI 0.1 mg/kg compared to placebo or EPI 0.01 mg/kg. There was an overall trend toward improved survival at 72 h in rats that received NaHCO3 which was most evident in the EPI 0.1 mg/kg group. We conclude that (1) EPI during CPR has a biphasic dose/response curve in terms of survival, when post-resuscitation effects are left untreated and (2) NaHCO3 doses greater than 1.0 mEq/kg may be necessary to treat the side-effects of high-dose EPI. Further work is needed to determine if treating the immediate post-resuscitation effects of high-dose EPI can prevent detrimental effects on long-term outcome.

Future directions for resuscitation research. IV. Innovative advanced life support pharmacology.

The topics discussed in this session include a partial review of laboratory and clinical studies examining the effects of adrenergic agonists on restoration of spontaneous circulation after cardiac arrest, the effects of varying doses of epinephrine, and the effects of novel vasopressors, buffer agents (NaHCO3, THAM, 'Carbicarb') and anti-arrhythmics (lidocaine, bretylium, amiodarone) in refractory ventricular fibrillation. Novel therapeutic approaches include titrating electric countershocks against electrocardiographic power spectra and of preceding the first countershocks with single or multiple drug treatments. These approaches need to be investigated further in controlled animal and patient studies. Epidemiologic data from randomized clinical outcome studies can give clues, but cannot document pharmacologic mechanisms in the dynamically changing events during attempts to achieve restoration of spontaneous circulation from prolonged cardiac arrest. Also, rapid drug administration by the intraosseous route was compared with intratracheal and intravenous (i.v.) drug administration. Many studies on the above treatments have yielded conflicting results because of differences between healthy hearts of animals and sick hearts of patients, differences in arrest (no-flow) times and cardiopulmonary resuscitation (CPR) (low-flow) times, different pharmacokinetics, different dose/response requirements, and different timing of drug administration during low-flow CPR versus during spontaneous circulation. The need to stabilize normotension and prevent rearrest by titrated novel drug administration, once spontaneous circulation has been restored, requires research. Most of the above topics require some re-evaluation in clinically realistic animal models and in cardiac arrest patients, especially by titration of old and new drug treatments against variables that can be monitored continuously during resuscitation.

Future directions for resuscitation research. II. External cardiopulmonary resuscitation basic life support.

In sudden cardiac deaths outside hospitals, the present performance of external cardiopulmonary resuscitation-basic life support (CPR-BLS), as a bridge to advanced life support (ALS) attempts for restoration of spontaneous circulation (ROSC), still yields suboptimal results. Therefore, future education research should develop more effective, simpler and quicker ways to enable everyone to acquire the necessary BLS skills. Individualized self-training by lay persons is being revived. Although airway control and direct mouth-to-mouth ventilation skills are difficult to acquire, they must continue to be taught to the lay public and health professionals, primarily for use on relatives and friends where infection risk is not a problem. In children and trauma victims, steps A and B alone may be lifesavers. The best way to ventilate and oxygenate during the initiation of brief external CPR-BLS should be re-evaluated. There is a great difference between animals and humans in the behavior of the airway and thorax during coma, and thus in the need for added positive pressure ventilation. During chest compressions in humans, steps A and B are needed. Details deserve re-evaluation. The low perfusion pressures (borderline blood flows) produced by standard external CPR remain the most serious limitation of this method. In spite of extensive efforts so far, novel laboratory research to remedy this limitation is important for the development of more effective emergency artificial circulation. The results of such studies are greatly influenced by different details in animal models. Active compression-decompression (ACD) external CPR, also called 'push-pull' CPR, with a plunger-type device used by hand or a machine, and intermittent abdominal compression (IAC) external CPR are both promising modifications of standard external CPR. Both need further experimental and clinical clarification. For BLS, developing a more effective purely manual CPR-BLS method for help in rapid ROSC should be given high priority. Portable external CPR machines need improvements. They will serve for bridging ROSC-resistant cases through transport and ALS attempts, primarily by freeing the hands of health professionals for more effective sophisticated ALS measures.

Future directions for resuscitation research. III. External cardiopulmonary resuscitation advanced life support.

This discussion about advanced cardiac life support (ACLS) reflects disappointment with the over 50% of out-of-hospital cardiopulmonary resuscitation (CPR) attempts that fail to achieve restoration of spontaneous circulation (ROSC). Hospital discharge rates are equally poor for in-hospital CPR attempts outside special care units. Early bystander CPR and early defibrillation (manual, semi-automatic or automatic) are the most effective methods for achieving ROSC from ventricular fibrillation (VF). Automated external defibrillation (AED), which is effective in the hands of first responders in the out-of-hospital setting, should also be used and evaluated in hospitals, inside and outside of special care units. The first countershock is most important. Biphasic waveforms seem to have advantages over monophasic ones. Tracheal intubation has obvious efficacy when the airway is threatened. Scientific documentation of specific types, doses, and timing of drug treatments (epinephrine, bicarbonate, lidocaine, bretylium) are weak. Clinical trials have failed so far to document anything statistically but a breakthrough effect. Interactions between catecholamines and buffers need further exploration. A major cause of unsuccessful attempts at ROSC is the underlying disease, which present ACLS guidelines do not consider adequately. Early thrombolysis and early coronary revascularization procedures should also be considered for selected victims of sudden cardiac death. Emergency cardiopulmonary bypass (CPB) could be a breakthrough measure, but cannot be initiated rapidly enough in the field due to technical limitations. Open-chest CPR by ambulance physicians deserves further trials. In searches for causes of VF, neurocardiology gives clues for new directions. Fibrillation and defibrillation thresholds are influenced by the peripheral sympathetic and parasympathetic nervous systems and impulses from the frontal cerebral cortex. CPR for cardiac arrest of the mother in advanced pregnancy requires modifications and outcome data. Until more recognizable critical factors for ROSC are identified, titrated sequencing of ACLS measures, based on physiologic rationale and sound judgement, rather than rigid standards, gives the best chance for achieving survival with good cerebral function.

Neurologic management following cardiac arrest.

Optimal neurologic outcome after cardiac arrest requires careful attention to the details of both intracranial and extracranial homeostasis. A high index of suspicion regarding the potential causes and complications of cardiac arrest facilitates discovery and treatment of problems before they adversely affect neurologic outcome. The future is bright for resuscitation research: Our fundamental understanding of cerebral ischemia and its consequences has dramatically improved, and this knowledge can hopefully be transferred to clinical useful modes of therapy. However, the transition from a promising, therapeutically effective intervention in animals to the demonstration that treatment is effective following cardiac arrest in humans is an important and difficult step. The patient population is heterogeneous before the insult, the duration and severity of the insult are variable, and the effectiveness of cardiopulmonary resuscitation varies among institutions. Therefore, the only means of demonstrating clinical efficacy is the performance of a large clinical trial. The Resuscitation Research Center at the University of Pittsburgh has developed and coordinated a multicenter, multinational team of investigators who have completed one definitive trial of postarrest barbiturate therapy and are currently completing a similar trial using a calcium entry blocker. Despite the formidable obstacles posed by such comprehensive efforts, they provide the mechanism for determining whether the cost of a new treatment modality is justified by the likelihood of improved mortality or morbidity.

A comparison of techniques for placement of double-lumen endobronchial tubes.

STUDY OBJECTIVE: To compare two methods of double-lumen endobronchial tube placement for thoracic surgery and to identify factors that provide a rational basis for placement method selection. DESIGN: Prospective, randomized study. SETTING: Teaching hospital. PATIENTS: 58 ASA physical status II, III, and IV patients scheduled for surgical procedures requiring elective left-sided endobronchial intubation. INTERVENTIONS: Patients were assigned randomly to either a group in which the initial placement method was the traditional approach of placing the endobronchial tube through the larynx and then advanced blindly into the left mainstem bronchus, or to a second group in which the left mainstem bronchus was intubated under direct vision using the fiberoptic bronchoscope. MEASUREMENTS AND MAIN RESULTS: Of the 32 patients who underwent the traditional approach, primary success occurred in 27 patients and eventual success in 30. In 27 patients undergoing the directed approach, primary success occurred in 21 patients and eventual success in 25. Two patients in each group required the alternative method. The blind approach took 88 (+/- 91) seconds and the directed approach took 181 (+/- 193) seconds (p = 0.029). Timing data were analyzed using analysis of variance with respect to method and secretions and then t-tests as appropriate. Categorical data were analyzed using the Kruskal-Wallis and Fisher's exact tests as appropriate. All values are reported as means +/- SD. CONCLUSION: Both the blind and directed approaches resulted in successful left mainstem placement of the endobronchial tube in the majority of patients but either method may fail when used alone. More time was required using the directed approach. Operator experience with both methods will increase the likelihood of success. The choice of the initial approach may be influenced by patient factors as well as available equipment and personnel.

Guidelines for the use of an insulin infusion for the management of hyperglycemia in critically ill patients

Objective: To evaluate the literature and identify important aspects of insulin therapy that facilitate safe and effective infusion therapy for a defined glycemic end point. Methods: Where available, the literature was evaluated using Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) methodology to assess the impact of insulin infusions on outcome for general intensive care unit patients and those in specific subsets of neurologic injury, traumatic injury, and cardiovascular surgery. Elements that contribute to safe and effective insulin infusion therapy were determined through literature review and expert opinion. The majority of the literature supporting the use of insulin infusion therapy for critically ill patients lacks adequate strength to support more than weak recommendations, termed suggestions, such that the difference between desirable and undesirable effect of a given intervention is not always clear. Recommendations: The article is focused on a suggested glycemic control end point such that a blood glucose ≥150 mg/dL triggers interventions to maintain blood glucose below that level and absolutely <180 mg/dL. There is a slight reduction in mortality with this treatment end point for general intensive care unit patients and reductions in morbidity for perioperative patients, postoperative cardiac surgery patients, post-traumatic injury patients, and neurologic injury patients. We suggest that the insulin regimen and monitoring system be designed to avoid and detect hypoglycemia (blood glucose ≤70 mg/dL) and to minimize glycemic variability. Important processes of care for insulin therapy include use of a reliable insulin infusion protocol, frequent blood glucose monitoring, and avoidance of finger-stick glucose testing through the use of arterial or venous glucose samples. The essential components of an insulin infusion system include use of a validated insulin titration program, availability of appropriate staffing resources, accurate monitoring technology, and standardized approaches to infusion preparation, provision of consistent carbohydrate calories and nutritional support, and dextrose replacement for hypoglycemia prevention and treatment. Quality improvement of glycemic management programs should include analysis of hypoglycemia rates, run charts of glucose values <150 and 180 mg/dL. The literature is inadequate to support recommendations regarding glycemic control in pediatric patients. Conclusions: While the benefits of tight glycemic control have not been definitive, there are patients who will receive insulin infusion therapy, and the suggestions in this article provide the structure for safe and effective use of this therapy.

Ischemic brain protection.

Despite advances in the understanding of the pathophysiology of cerebral ischemia, no single brain resuscitation therapy has yet been shown to be clinically superior to brain-oriented intensive care. Basic concepts in cardiopulmonary-cerebral resuscitation (CPCR) are discussed, as are two specific phases of CPCR, cerebral preservation and cerebral resuscitation. Cerebral preservation is initiated during cardiac arrest (ie, prior to restoration of spontaneous circulation [ROSC]) and includes use of artificial perfusion techniques and drugs to produce cerebral perfusion during this phase. Cerebral resuscitation is brain-oriented therapy initiated after ROSC. Pharmacologic agents currently under study for cerebral resuscitation include the barbiturates, calcium antagonists, and iron chelators. With respect to defining efficacy of the pharmacologic agents, the concept of therapeutic window is important. Although no agent has been proven clinically, several appear to be promising.

Cerebral preservation during cardiopulmonary resuscitation.

Thirty-two dogs subjected to 4 min of ventricular fibrillation were equally divided into four treatment groups: (a) immediate defibrillation (control); or 30 min of (b) standard CPR (SCPR), (c) simultaneous ventilation-compression CPR (SVC-CPR), or (d) open-chest CPR (OCCPR). After 30 min of CPR, restoration of spontaneous circulation was attempted using drug therapy and countershocks and the animals maintained for 24 h or until refractory hypotension occurred. During CPR, OCCPR yielded higher mean arterial and lower central venous pressures than either external method. Circulation was restored in all control dogs, and by 24 h they had nearly normal neurologic deficit scores. In the SCPR group, the heart was restarted in six dogs. Five of these dogs had severe neurologic damage and did not survive 24 h. The animal that survived 24 h, however, was nearly normal neurologically. Although circulation was restored in five SVC-CPR dogs, all were brain-dead and none survived 24 h. In the OCCPR group, seven animals survived 24 h and their neurologic deficit scores were not significantly different from control values. We conclude that OCCPR is greatly superior to SCPR and SVC-CPR with respect to preservation of the brain during resuscitation.