Cardiac arrest: use of a cardiac monitor-pacemaker in diagnosis and management.
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Cardiology↗
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Suspended animation for delayed resuscitation from prolonged cardiac arrest that is unresuscitable by standard cardiopulmonary-cerebral resuscitation.
Standard cardiopulmonary-cerebral resuscitation fails to achieve restoration of spontaneous circulation in approximately 50% of normovolemic sudden cardiac arrests outside hospitals and in essentially all victims of penetrating truncal trauma who exsanguinate rapidly to cardiac arrest. Among cardiopulmonary-cerebral resuscitation innovations since the 1960s, automatic external defibrillation, mild hypothermia, emergency (portable) cardiopulmonary bypass, and suspended animation have potentials for clinical breakthrough effects. Suspended animation has been suggested for presently unresuscitable conditions and consists of the rapid induction of preservation (using hypothermia with or without drugs) of viability of the brain, heart, and organism (within 5 mins of normothermic cardiac arrest no-flow), which increases the time available for transport and resuscitative surgery, followed by delayed resuscitation. Since 1988, we have developed and used novel dog models of exsanguination cardiac arrest to explore suspended animation potentials with hypothermic and pharmacologic strategies using aortic cold flush and emergency portable cardiopulmonary bypass. Outcome evaluation was at 72 or 96 hrs after cardiac arrest. Cardiopulmonary bypass cannot be initiated rapidly. A single aortic flush of cold saline (4 degrees C) at the start of cardiac arrest rapidly induced (depending on flush volume) mild-to-deep cerebral hypothermia (35 degrees to 10 degrees C), without cardiopulmonary bypass, and preserved viability during a cardiac arrest no-flow period of up to 120 mins. In contrast, except for one antioxidant (Tempol), explorations of 14 different drugs added to the aortic flush at room temperature (24 degrees C) have thus far had disappointing outcome results. Profound hypothermia (10 degrees C) during 60-min cardiac arrest induced and reversed with cardiopulmonary bypass achieved survival without functional or histologic brain damage. Further plans for the systematic development of suspended animation include the following: a) aortic flush, combining hypothermia with mechanism-specific drugs and novel fluids; b) extension of suspended animation by ultraprofound hypothermic preservation (0 degrees to 5 degrees C) with cardiopulmonary bypass; c) development of the most effective suspended animation protocol for clinical trials in trauma patients with cardiac arrest; and d) modification of suspended animation protocols for possible use in normovolemic ventricular fibrillation cardiac arrest, in which attempts to achieve restoration of spontaneous circulation by standard external cardiopulmonary resuscitation-advanced life support have failed.
Advanced Cardiac Life Support↗
Intra-operative cardiac arrests.
This is a review of patients who had cardiac arrest in the operating suites at the University College Hospital (UCH), Ibadan between January 1994 and December 1998. The main objectives of the study were to evaluate the incidence of intraoperative cardiac arrests, identify associated factors and, in particular, those factors that might be essential for better prognosis. The study was retrospective, descriptive and cross-sectional. The figures were retrieved from the theatre records, the intensive care records, case notes and pathology reports. During the study period, 6,356 operations were performed. There were 35 cardiac arrests giving an incidence of 55 per 10,000 operations. Of the 35 cases, 18(51.4%) were males while 17(48.6%) were females. The age range was 4 months to 84 years (mean 32.5 years) with wide distribution through the decades. Of the twenty-four patients (68.6%) that were done as emergency cases, four patients (17.1%) recovered fully. Of the 11(31.4%) elective cases, 5 (41.7%) made full recovery. Ten patients (28.6%) were ASA I & II, while 25 (71.4%) were graded ASA status III to V. The factors associated with cardiac arrest in this study included emergency operation and the ASA status.
Adult↗
Use of implantable cardioverter defibrillators after out-of-hospital cardiac arrest: a prospective follow-up study.
BACKGROUND: Survivors of out-of-hospital cardiac arrest are at high risk of recurrent arrests, many of which could be prevented with implantable cardioverter defibrillators (ICDs). We sought to determine the ICD insertion rate among survivors of out-of-hospital cardiac arrest and to determine factors associated with ICD implantation. METHODS: The Ontario Prehospital Advanced Life Support (OPALS) study is a prospective, multiphase, before-after study assessing the effectiveness of prehospital interventions for people experiencing cardiac arrest, trauma or respiratory arrest in 19 Ontario communities. We linked OPALS data describing survivors of cardiac arrest with data from all defibrillator implantation centres in Ontario. RESULTS: From January 1997 to April 2002, 454 patients in the OPALS study survived to hospital discharge after experiencing an out-of-hospital cardiac arrest. The mean age was 65 (standard deviation 14) years, 122 (26.9%) were women, 398 (87.7%) had a witnessed arrest, 372 (81.9%) had an initial rhythm of ventricular tachycardia or ventricular fibrillation (VT/VF), and 76 (16.7%) had asystole or another arrhythmia. The median cerebral performance category at discharge (range 1-5, 1 = normal) was 1. Only 58 (12.8%) of the 454 patients received an ICD. Patients with an initial rhythm of VT/VF were more likely than those with an initial rhythm of asystole or another rhythm to undergo device insertion (adjusted odds ratio [OR] 9.63, 95% confidence interval [CI] 1.31-71.50). Similarly, patients with a normal cerebral performance score were more likely than those with abnormal scores to undergo ICD insertion (adjusted OR 12.52, 95% CI 1.74-92.12). INTERPRETATION: A minority of patients who survived cardiac arrest underwent ICD insertion. It is unclear whether this low usage rate reflects referral bias, selection bias by electrophysiologists, supply constraint or patient preference.
Age Distribution↗
Modeling the occurrence of cardiac arrest as a poisson process.
STUDY OBJECTIVE: A statistical model for the occurrence of cardiac arrest has not been described in the literature. Independent events occurring along the time axis may constitute a Poisson process, described by the Poisson and exponential probability distributions. This statistical model defines the probability distribution of events occurring within time intervals and enables construction of confidence intervals for the mean rate. Moreover, the probability that 2 or more events will occur close in time can be estimated from knowledge of the mean rate. We investigated whether the occurrence of cardiac arrests constitutes a Poisson process. METHODS: Time and date for cardiac arrests requiring CPR out of hospital (county population, 155,000) or in hospital (850 beds) during 5 years were analyzed. Goodness of fit was assessed by comparing the observed weekly counts of cardiac arrests and the observed time intervals between such events with the values predicted from the model. RESULTS: The Poisson parameter estimates (mean weekly rates) for out-of-hospital and in-hospital cardiac arrest were 2.02 and 1.09 events per week, respectively. There was close agreement between observed and predicted values, indicating an adequate model fit. CONCLUSION: Occurrence of cardiac arrest along the time axis constitutes a Poisson process and may be adequately modeled by the Poisson and exponential distributions. The model provides information about the nature of these events and allows for probability calculations based on the mean rate of events. Examples of such calculations are given.
Cardiopulmonary Resuscitation↗
Continuous electrocardiographic monitoring and cardiac arrest outcomes in 8,932 telemetry ward patients.
OBJECTIVE: To estimate the benefit of routine electrocardiographic (ECG) telemetry monitoring on in-hospital cardiac arrest survival. METHODS: In a tertiary care hospital, all telemetry ward admissions and cardiac arrests occurring over a five-year period were reviewed. Ward location and survival to discharge were determined for all patients outside of critical care areas. RESULTS: During the study period, 8,932 patients were admitted to the telemetry ward, and 20 suffered cardiac arrest (0.2%; 95% CI = 0.1 to 0.3). Telemetry monitors signaled the onset of cardiac arrest in only 56% (95% CI = 30 to 80) of monitored arrests. Three patients survived to discharge, and in two of these three patients the arrest onset was signaled by the monitor. This yields a monitor-signaled survival rate among telemetry ward patients of 0.02% (95% CI = 0 to 0.05). All survivors suffered significant arrhythmias prior to their cardiac arrests. CONCLUSIONS: Cardiac arrest is an uncommon event among telemetry ward patients, and monitor-signaled survivors are extremely rare. Routine telemetry offers little cardiac arrest survival benefit to most monitored patients, and a more selective policy for telemetry use might safely avoid ECG monitoring for many patients.
Aged↗
Electrophysiologic testing in the management of survivors of out-of-hospital cardiac arrest.
Forty-five patients survived a cardiac arrest due to ventricular tachycardia (VT) or ventricular fibrillation (VF). Programmed ventricular stimulation was performed with the patients taking no antiarrhythmic medications. Sustained VT was induced in 26 patients (58%) and nonsustained VT in 8 (18%). With treatment aimed at the underlying heart disease (plus empiric antiarrhythmic therapy in 2 patients), the 11 patients who had no inducible VT have had no recurrence of symptomatic VT or cardiac arrest over a follow-up period of 19 +/- 9 months (mean +/- standard deviation). Conventional antiarrhythmic drugs suppressed the induction of VT and were used for chronic treatment in 9 of 34 patients (26%) with inducible VT. Three of these 9 patients had recurrent VT or sudden death, whereas 6 have had no recurrence over follow-up of 20 +/- 7 months. In the 25 of 34 patients in whom the induction of VT was not suppressed by conventional antiarrhythmic drugs, 23 were treated with amiodarone (daily dose 550 +/- 120 mg), and 2 underwent coronary artery bypass grafting with either aneurysmectomy or map-directed endocardial resection. One of the latter 2 patients died suddenly 12 months after surgery. Among the 23 patients treated with amiodarone, 2 had fatal VT or sudden death and 21 (91%) did not, over 18 +/- 14 months of follow-up. In survivors of a cardiac arrest, the chief value of electrophysiologic testing is in identifying patients without inducible VT, who appear to have a low risk of recurrent sudden death with treatment directed at the underlying heart disease. Serial electropharmacologic testing with conventional antiarrhythmic drugs is disappointing, with a low incidence of arrhythmia suppression.
Adult↗
Characteristics of cardiac arrest in cancer patients as a predictor of survival after cardiopulmonary resuscitation.
BACKGROUND: Despite advances in cardiopulmonary resuscitation and the education of its providers, survival remains dismal for cancer patients suffering in-hospital cardiac arrest. In an effort to determine if characteristics of cardiac arrest would represent a useful parameter for prognostication and recommendations regarding the suitability of ongoing resuscitation for various groups, this review was undertaken for patients who experienced in-hospital cardiac arrest. METHODS: A retrospective study of data gathered between January 1993 and December 1997 was undertaken in a 518-bed comprehensive cancer center. The records of 243 inpatients who experienced cardiac arrest and received cardiopulmonary resuscitation were reviewed, and their course observed until hospital discharge or death. RESULTS: Sixteen of 73 patients (22%) who had sudden, unanticipated cardiac arrests survived to be discharged from the hospital; however, none (0 of 171) of the patients who experienced an anticipated cardiac arrest survived (P < 0.001). Logistic regression analysis revealed that anticipated cardiac arrest associated with metabolic derangement was an independent predictor of hospital mortality. CONCLUSIONS: Patients experiencing an anticipated cardiac arrest, the course of which could not be interrupted through aggressive management in an intensive care unit, have an extremely poor prognosis. Ongoing resuscitative measures in these patients need not be routinely provided. The authors suggest an algorithm for resuscitation that evaluates the characteristics of the arrest as a prognostic factor. This algorithm should be implemented once progressive deterioration spirals toward cardiac arrest that cannot be prevented. Such an approach should avoid painful and costly interventions that are futile with the present techniques of cardiopulmonary resuscitation.
Algorithms↗
Methodology-dependent variation in documentation of outcome predictors in out-of-hospital cardiac arrest.
OBJECTIVE: To identify variation in outcome predictor documentation in out-of-hospital cardiac arrest associated with two different methods of data collection: concurrent questioning of personnel following a resuscitation attempt and archival report review. METHODS: All patients > or = 18 years old who had out-of-hospital cardiac arrests, verified using the New York City 911 telephone system, between October 1, 1990, and April 1, 1991, were eligible for inclusion. The authors reviewed the first 200 cases of presumed primary cardiac arrest involving a resuscitation attempt among 3,243 consecutive ambulance call reports for cardiac arrest occurring during the study period. This archival data set was compared with data for the same 200 cases gathered through direct interview of field personnel by trained paramedics. The two data sets had been compiled independently by different individuals, using the same data collection instrument, which conformed to the Utstein template. RESULTS: Comparison of the data obtained from ambulance records with the data obtained from interviews of prehospital personnel revealed several areas of variance. Of note was a significantly lower proportion of bystander-witnessed ventricular fibrillation (VF) in the data set gathered from written reports (7% vs 18%; 95% CI for the difference 4-18%; p = 0.001). CONCLUSION: differences in methods of collection of out-of-hospital cardiac arrest data are associated with a more than twofold variation in the reported incidences of witnessed cardiac arrests manifesting as VF. Methodology-dependent variation in this important "denominator" may produce substantially different estimates of survival within the same cohort of patients.
Adult↗
The cerebral 'no-reflow' phenomenon after cardiac arrest in rats--influence of low-flow reperfusion.
OBJECTIVE: Experimental data indicate that early microcirculatory reperfusion is disturbed after cardiac arrest. We investigated the influence of prolonged cardiac arrest and basic life support (BLS) procedures on the quality of cerebral microcirculatory reperfusion. MATERIALS AND METHODS: In mechanically ventilated male Wistar rats anesthetized with N2O and halothane, cardiac arrest was induced by electrical fibrillation. Ten animals (group I) were subjected to 17 min of cardiac arrest (no-flow). Nine additional animals (group II) underwent only 12 min of cardiac arrest (no-flow), which was followed by a 5-min phase of BLS (i.e. mechanical ventilation and external cardiac compressions). In both groups, advanced resuscitation procedures including mechanical ventilation, external cardiac massage, 0.2 mg kg-1 epinephrine, 0.5 mmol kg-1 NaHCO3, and defibrillation were started 17 min after induction of cardiac arrest. The perfusion of the cerebral microcirculation was visualized by injection of 0.3 g kg-1 15% fluorescein isothiocyanate (FITC)-albumin 5 min after restoration of spontaneous circulation (ROSC), and the animals were decapitated 2 min later. The left hemispheres were fixed in 4% formalin, and coronal sections of 200 microns thickness at three different standard levels of the rat brain were investigated using fluorescence microscopy. Areas without capillary filling (cerebral 'no-reflow') were identified and calculated. RESULTS: ROSC could be achieved in five of 10 animals (50%) of group I, and in six of nine animals (67%) of group II (P = n.s.). The severity of cerebral 'no-reflow' was higher in group II compared with group I (6.9 +/- 7.6 vs. 0.7 +/- 0.7% of total sectional areas; P < or = 0.05). Two sham-operated animals showed homogeneous reperfusion. CONCLUSIONS: Wistar rats did not develop a marked cerebral 'no-reflow' phenomenon after circulatory arrest. A relevant degree of cerebral 'no-reflow' occurred, however, in animals subjected to a phase of BLS before circulatory stabilization. Therefore, low-flow states following prolonged cardiocirculatory arrest may aggravate early cerebral microcirculatory reperfusion disorders.
Animals↗
Hypothermia and ERK activation after cardiac arrest.
Mild hypothermia improves survival and neurological outcome after cardiac arrest, as well as increasing activation of the extracellular-signal-regulated kinase (ERK) in hippocampus. ERK signaling is involved in neuronal growth and survival. We tested the hypothesis that the beneficial effects of hypothermia required ERK activation. ERK activation was measured by immunoblotting with phosphorylation-specific antibodies. Rats (n = 8 per group) underwent 8 min of asphyxial cardiac arrest and were resuscitated with chest compressions, ventilation, epinephrine and bicarbonate. At 30 min after resuscitation, vehicle (50% saline:50% DMSO) or the ERK kinase inhibitor U0126 (100 microg) was infused into the lateral ventricle. Cranial temperature was kept at either 33 degrees C (hypothermia) or 37 degrees C (normothermia) between 1 and 24 h. Neurological function was assessed daily for 14 days. Surviving neurons were counted in the hippocampus. A dose of 100 mug U0126 inhibited ERK bilaterally for 12 to 24 h and decreased phosphorylation of the ERK substrates ATF-2 and CREB. As in previous studies, hypothermia improved survival, neurological and histological outcome after cardiac arrest. However, survival, neurological score and histology did not differ between U0126 and vehicle-treated rats after cardiac arrest. Therefore, a dose of U0126 sufficient to inhibit biochemical markers of ERK signaling in hippocampus does not alter the beneficial effects of hypothermia induced after resuscitation in rats and did not affect recovery of normothermia-treated rats. These results suggest that hypothermia-induced improvement in outcomes does not require ERK activation.
Animals↗
Paediatric out-of-hospital cardiac arrests: epidemiology and outcome.
INTRODUCTION: Little information is available regarding the outcome of children in our local population who sustained pre-hospital cardiac arrest. This study was performed to determine the survival rate among children after out-of-hospital cardiac arrest, to describe the epidemiology, and to identify predictors of survival. METHODS: The records of 85 children who presented to a paediatric emergency department in cardiac arrest, between 1 June 1997 and 31 September 2001, were reviewed. The characteristics of the patients, cardiac arrest circumstances, and the outcomes of arrest were analysed. RESULTS: 85 children presented to the emergency department in cardiac arrest during the 52-month study period. 26 out of 85 children (30.6 percent) with cardiac arrest had return of spontaneous circulation (ROSC) after resuscitation efforts at the emergency department. Only four (4.7 percent) survived to be discharged from hospital and three of them survived beyond one year. Two of the cardiac arrest survivors had no change in the neurological status, with the remaining two sustaining severe neurological deficits. Emergency medical service was activated in only 63.7 percent of the patients. 34 percent of the arrests were witnessed, and only 22.9 percent of the children received bystander cardiopulmonary resuscitation (CPR). The positive predictors for survival to hospital discharge in a bivariate analysis were witnessed arrest (p-value is equal to 0.012), presence of bystander CPR (p-value is equal to 0.003), and duration of resuscitation (p-value is equal to 0.028). None who had more than 30 minutes of resuscitation in the emergency department survived. In a multivariate analysis with a logistic regression model, the only two independent predictors of ROSC were witnessed arrest (odds ratio is 3.049; 95% confidence interval [CI] is 1.101-8.444; p-value is equal to 0.032) and duration of resuscitation (odds ratio is 0.353; 95% CI is 0.146 - 0.854; p-value is equal to 0.021). CONCLUSION: Out-of-hospital cardiac arrest in children has a poor prognosis and prolonged resuscitation at the emergency department beyond 30 minutes does not improve survival.
Adolescent↗
Case conference. A 55-year-old man develops ventricular tachycardia and cardiac arrest during non-cardiac vascular surgery.
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Anesthesia, General↗
Prospective observational survey of the utilisation of anaesthetists and the outcome following cardiac arrest calls.
BACKGROUND AND AIMS: We wanted to determine whether the practice of routinely sending an anaesthetist to cardiac arrests is common within Scotland. We also wished to evaluate the interventions performed by our intensive care anaesthetist when responding to cardiac arrest calls. METHODS: We performed a telephone survey of the 26 Scottish hospitals with an intensive care unit. We conducted a prospective observational survey over a period of six months in one Scottish teaching hospital. Structured interviews with the anaesthetist who responded to the cardiac arrest call were undertaken. RESULTS: Routine attendance of an anaesthetist at cardiac arrests occurs in 25 of the 26 hospitals surveyed. We analysed 68 of 73 arrest calls. In 28 calls (41%) there was no requirement for anaesthetic intervention. In 40 (59%) the anaesthetist intervened. The interventions were for cardiac arrest procedures in 33 cases and ventilatory failure in the remaining 7 cases. One patient survived to hospital discharge: a mortality of 98%. CONCLUSIONS: Patients who remain in cardiac arrest upon the arrival of the anaesthetist have a very high mortality. The practice of routinely sending an anaesthetist to cardiac arrest calls is not justified.
Anesthesiology↗
Public locations of cardiac arrest. Implications for public access defibrillation.
BACKGROUND: The purpose of this study was to describe the public locations of cardiac arrest and to estimate the annual incidence of cardiac arrest per site to determine optimal placement of automatic external defibrillators (AEDs). This was a retrospective cohort study. METHODS AND RESULTS: Locations of cardiac arrest were abstracted from data collected by emergency medical service programs in Seattle and King County, Washington, from January 1, 1990, through December 31, 1994. Types of commercial and civic establishments were tallied and grouped into 23 location categories consistent with Standard Industrial Codes, and the number of sites within each location category was determined. With the addition of "public outdoors" and "automobiles" as categories, there were 25 location categories. During the study period, 7185 arrests occurred, 1130 (16%) of which were in public locations. An annual incidence of cardiac arrest per site was calculated. Ten location categories with 172 sites were identified as having a higher incidence of cardiac arrest (> or = .03 per year per site). Thirteen location categories had a lower incidence of arrest (< or = .01 per year per site). There were approximately 71,000 sites within these categories. CONCLUSIONS: Placement of 276 AEDs in the 172 higher-incidence sites would have provided treatment for 134 cardiac arrest patients in a 5-year period, 60% of whom were in ventricular fibrillation. We estimate between 8 and 32 lives could be saved in 5 years. To cover the remaining 347 arrests occurring in public in a 5-year period, defibrillators would have to be placed in 71,000 sites, not including outdoors and automobiles. Placement of AEDs in public locations can be guided by the site-specific incidence of arrest.
Electric Countershock↗
Evaluation of the use of automatic external defibrillation in out-of-hospital cardiac arrest in Hong Kong.
A retrospective 6-month audit of out-of-hospital cardiac arrests in Hong Kong following the introduction of automatic external defibrillators is presented. During the 6-month period from 1 July 1995 to 31 December 1995, resuscitation was attempted on 754 patients. Of the 744 patients with cardiac arrest whose records were available, 53.6% had a witnessed arrest. Few cardiac arrest patients (8.9%) received bystander cardiopulmonary resuscitation (CPR) and the majority (80%) of arrests occurred at home. Six hundred and forty-three (86.4%) patients were declared dead on arrival at hospital or in the Accident and Emergency department; 89 (12%) died in hospital and only 12 (1.6%) were discharged alive. The average ambulance response interval (call receipt to arrival of ambulance at scene) was 6.42 min. The average arrest-to-first-shock interval was 23.77 min. Factors predicting survival included initial rhythm and arrest-to-first-shock interval. The survival rate of 1.6% is low by world standards. To improve the survival rates of people with out-of-hospital cardiac arrest, the arrest-to-call interval must be reduced and the frequency of bystander CPR assistance increased. Once these changes are in place, a beneficial effect from the use of pre-hospital defibrillation might be seen.
Adolescent↗
Cardiac arrest in medical and dental practices: implications for automated external defibrillators.
BACKGROUND: To determine the need for placing automated external defibrillators (AEDs) in medical and dental practices, we identified cardiac arrests at these locations. METHODS: Locations of cardiac arrest were abstracted from Emergency Medical Services data from January 1, 1990, through December 31, 1996. We calculated the annual incidence of cardiac arrest per type of practice. RESULTS: There were 142 cardiac arrests in medical or dental practices. Dialysis centers had a relatively high incidence of cardiac arrest (>/=0.746 per practice annually). Cardiology, internal and family medicine, and urgent care centers had a medium incidence (>/=0.01 per practice annually). All other medical and dental practices had a low incidence (</=0.002 annually). CONCLUSIONS: Placement of 779 AEDs in the high- and medium-incidence practices would have provided treatment for 112 patients with cardiac arrest in 7 years. To provide for the 16 cardiac arrests in low-incidence practices, an additional 1928 AEDs would be required.
Age Distribution↗
Prolonged cardiac arrest and resuscitation in dogs: brain mitochondrial function with different artificial perfusion methods.
Clinical techniques for artificial perfusion have not previously been examined directly for their effects on brain high-energy metabolism. Our study involved 24 large mongrel dogs that were anesthetized, instrumented for central venous intravenous access, and subjected to craniotomy to expose the dura and underlying parietal cortex. The animals were divided into the following six experimental groups of four animals each: nonischemic controls; 15-minute cardiac arrest without resuscitation; 45-minute cardiac arrest without resuscitation; 15-minute cardiac arrest plus 30 minutes resuscitation with conventional cardiopulmonary resuscitation (CPR); 15-minute cardiac arrest plus 30 minutes resuscitation with interposed abdominal compression (IAC) CPR; and 15-minute cardiac arrest plus 30 minutes resuscitation with internal cardiac massage. Cardiac arrest was induced by central venous injection of KCl 0.6 mEq/kg, and it was confirmed by continuous ECG monitoring. The three active resuscitation models included administration of NaHCO3 and epinephrine, but no attempt was made to restart the heart by defibrillation during resuscitation. At the indicated time in each group, a 4- to 5-g sample of brain was removed through the craniotomy, immediately cooled to 0 C and processed for isolation of mitochondria. The mitochondria were studied for their content of superoxide dismutase and for quantitative oxygen consumption with glutamate/malate substrate during resting and ADP-stimulated respiration. Our results show a significant drop in brain mitochondrial superoxide dismutase activity during the first 15 minutes of cardiac arrest. There is minimal injury to brain mitochondrial oxygen consumption during both 15 and 45 minutes of complete ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗