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Clinical experience with portable cardiopulmonary bypass in cardiac arrest patients.

To evaluate the use of portable cardiopulmonary bypass as a resuscitative tool and its impact on long-term survival of patients in cardiac arrest, we reviewed the results of 32 consecutive patients resuscitated by cardiopulmonary bypass for cardiac arrest or severe hemodynamic compromise at Northwestern Memorial Hospital over a 2-year period. Overall survival was 12.5%. Only 1 (3.4%) of the 29 patients who had cardiac arrest survived and left the hospital. All 3 patients who had severe hemodynamic compromise but not cardiac arrest were long-term survivors. Our study suggests that portable cardiopulmonary support systems used as a resuscitative tool do not prolong the survival of most cardiac arrest patients but may be useful for patients with shock due to mechanical causes and for those with profound hemodynamic compromise due to ischemia or myocardial infarction. Portable heart-lung machines can provide patients with excellent hemodynamic support; however, neurological or cardiac recovery is unlikely once cardiac arrest occurs.

Cardiopulmonary Bypass↗

Long-term survival after prehospital cardiac arrest: analysis of outcome during an 8 year study.

We analyzed long-term follow-up data accumulated during an 8 year study of survivors of prehospital cardiac arrest. All patients included in this study were primary entrants via community-based rescue systems; patients who were tertiary referrals (survivors of cardiac arrest from other hospitals) were not included in this analysis. In the group of 61 patients entering our study between 1975 and 1980, with a follow-up to 1983, there have been a total of 24 deaths (39%). Sixteen of the 24 deaths were the result of recurrent cardiac arrest; eight were nonsudden cardiac deaths or noncardiac deaths. The mean duration from entry to death in the nonsurvivors was 27.5 +/- 19.7 months, and the time from the index event to last follow-up in the long-term survivors was 59.9 +/- 19.4 months. Life table analysis demonstrated a 10% rate of recurrence of cardiac arrest in the first year, with a 5% per year rate in each of the subsequent 3 years. Left ventricular ejection fractions at entry were not significantly different between survivors (mean = 45.3 +/- 13.6%) and nonsurvivors (mean = 37.6 +/- 12.6%), and the severity of ejection fraction abnormality at entry did not correlate with time to death in the nonsurvivors. However, ejection fraction was significantly lower in patients who died from causes other than recurrent cardiac arrest than in those who died of cardiac arrest (24.5 +/- 9.1% vs 42.7 +/- 9.2%; p less than .002).(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Arrhythmia Agents↗

Central venous pH as a predictor of arterial pH in prolonged cardiac arrest.

Sixty-five patients who arrived in the emergency department in cardiac arrest were studied prospectively to determine whether central venous pH could be used as an accurate predictor of arterial pH in prolonged cardiac arrest. Central venous and arterial access were obtained as soon as possible after arrival in the emergency department. Simultaneous arterial and venous samples were drawn and sent for blood gas analysis. Under normal conditions, central venous pH (pHcv) approximates arterial pH (pHa). In prolonged cardiac arrest, however, our data reveal a mean pHa of 7.31 +/- 0.25 and a mean pHcv of 7.08 +/- 0.19. There was moderate correlation between pHa and pHcv when all patients were considered (r = .69, P less than .01). The correlation was excellent, however, in the subgroup of 15 patients who had a pulse at some point during resuscitation (r = .95, P less than .01). In 13 of these 15 patients the acid base status would have been managed correctly based on the predicted pHa (pHcv + 0.12 correction factor). The pHcv was also valuable in identifying a second subgroup of patients who required no further bicarbonate therapy; all patients who had a pHcv greater than or equal to 7.15 had a pHa greater than 7.30 (21 patients). The central venous pH was found to be a useful index of arterial pH when applied to a definable subset of patients, which in this study constituted 45% of all patients in prolonged cardiac arrest.

Acidosis↗

Selective aortic arch perfusion with hemoglobin-based oxygen carrier-201 for resuscitation from exsanguinating cardiac arrest in swine.

OBJECTIVE: The prospects for resuscitation after blunt traumatic cardiac arrest are dismal. Selective aortic arch perfusion (SAAP) with a hemoglobin-based oxygen carrier (HBOC-201) offers a potentially effective therapy. This study evaluated the acute cardiovascular and metabolic effects of SAAP with HBOC-201 in an exsanguination model of cardiac arrest. DESIGN: Randomized, controlled, laboratory investigation. SETTING: University research laboratory. SUBJECTS: Domestic swine, 25-39 kg. INTERVENTIONS: Partial resection of four liver lobes rapidly led to profound hemorrhagic shock and subsequent cardiac arrest at 10-13 mins. At 15 mins, swine were randomized to receive either SAAP with oxygenated lactated Ringer's (LR) solution (n = 6) or SAAP with oxygenated HBOC-201 (n = 6) at a rate of 10 mL x kg(-1) x min(-1) until return of spontaneous circulation with a mean aortic pressure of 60 mm Hg (8.0 kPa) was achieved. Epinephrine (0.005 mg/kg) was given via intra-aortic route every 30 secs as needed to promote return of spontaneous circulation beginning at 18 mins after onset of liver injury (3 mins after beginning SAAP). MEASUREMENTS AND MAIN RESULTS: Mean aortic pressure, cardiac output, total blood loss, and time of arrest were similar for both groups before SAAP therapy. In the SAAP-HBOC group, return of spontaneous circulation with a sustained mean aortic pressure of 60 mm Hg (8.0 kPa) was achieved in six of six swine at 1.9 +/- 0.3 mins of SAAP, and none of these swine required epinephrine. In the SAAP-LR group, no swine (from a total of six) achieved return of spontaneous circulation before intra-aortic epinephrine administration, and only two of six swine had brief return of spontaneous circulation with an mean aortic pressure of 60 mm Hg (8.0 kPa) after intra-aortic epinephrine that was sustained for <10 mins. One-hour survival was five of six in the SAAP-HBOC group and none of six in the SAAP-LR group (p <.05, Fisher's exact test). CONCLUSION: SAAP with oxygenated HBOC-201 rapidly restored viable cardiovascular function after exsanguinating cardiac arrest in this swine model of liver injury with profound hemorrhagic shock.

Animals↗

Paramedic activities, drug administration and survival from out of hospital cardiac arrest.

OBJECTIVE: To examine the impact of administration of cardioactive drugs on the outcome from out of hospital cardiac arrest. DESIGN: Longitudinal observational cohort study with historical controls before and after the introduction of drug use in cardiac arrest by paramedics. SUBJECTS: Adult patients who had sustained an out of hospital cardiac arrest of cardiac aetiology and were treated by paramedics. SETTING: Edinburgh, Scotland. OUTCOME MEASURES: Return of spontaneous circulation, admission to and discharge from hospital. RESULTS: There was no significant difference in the demographics between Period 1 (prior to drug administration) and Period 2 (after). There was no difference in outcome between Period 1 and Period 2 for all three parameters, return of spontaneous output 30.1 versus 35%, admission to hospital 18.9 versus 24.5% and discharge 5.8 versus 6.5%. If the presenting rhythm of VF/pulseless VT alone was considered survival to hospital discharge was 12.1% in Period 1 and 10.3% in Period 2. CONCLUSION: The addition of cardioactive drug administration to the treatment of out of hospital cardiac arrest does not improve survival.

Adult↗

Aetiology of unsuccessful prehospital witnessed cardiac arrest of unclear origin.

OBJECTIVES: To determine, by means of autopsy, the cause of death following unsuccessful cardiopulmonary resuscitation of patients with a witnessed prehospital cardiac arrest of unclear origin. METHOD: Observational study of all prehospital-witnessed cardiac arrest of unclear origin over a period of 19 months in the emergency medical service region of a tertiary care hospital. RESULTS: During the study period, 211 prehospital cardiopulmonary resuscitation attempts were recorded. In 144 study participants, cardiopulmonary resuscitation was not successful: there was no return of spontaneous circulation. Cardiac arrest of traumatic or other clear origin was not considered, nor were paediatric cases. Thirty out of the 114 remaining patients underwent an autopsy (26.3%). The main aetiology of cardiac arrest in this selected population was ischaemic heart disease in 16 out of 30 patients (53.3%) followed by pulmonary embolism in four patients (13.3%) and vascular disease other than coronary disease in two patients (6.7%). Other causes consisted of hypertrophic obstructive cardiomyopathy (one patient) (3.3%) and poisoning (one patient) (3.3%). The cause of death could not be identified in six cardiac arrest victims (20%). CONCLUSIONS: Ischaemic heart disease and pulmonary embolism account for 66.6% of all witnessed cardiac arrest with no return of spontaneous circulation.

Adult↗

Mild hypothermia after cardiac arrest in dogs does not affect postarrest multifocal cerebral hypoperfusion.

BACKGROUND AND PURPOSE: Although mild resuscitative hypothermia (34 degrees C) immediately after cardiac arrest improves neurological outcome in dogs, its effects on cerebral blood flow and metabolism are unknown. METHODS: We used stable xenon-enhanced computed tomography to study local, regional, and global cerebral blood flow patterns up to 4 hours after cardiac arrest in dogs. We compared a normothermic (37.5 degrees C) control group (group I, n = 5) with a postarrest mild hypothermic group (group II, n = 5). After ventricular fibrillation of 12.5 minutes and reperfusion with brief cardiopulmonary bypass, the ventilation, normotension, normoxia, and mild hypocapnia were controlled to 4 hours after cardiac arrest. Group II received (minimal) head cooling during cardiac arrest, followed by systemic bypass cooling (to 34 degrees C) during the first hour of reperfusion after cardiac arrest. RESULTS: The postarrest homogeneous transient hyperemia was followed by global hypoperfusion from 1 to 4 hours after arrest, with increased "no-flow" and "trickle-flow" voxels (compared with baseline), without group differences. At 1 to 4 hours, mean global cerebral blood flow in computed tomographic slices was 55% of baseline in group I and 64% in group II (NS). No flow (local cerebral blood flow < 5 mL/100 cm3 per minute) occurred in 5 +/- 2% of the voxels in group I versus 9 +/- 5% in group II (NS). Trickle flow (5 to 10 mL/100 cm3 per minute) occurred in 10 +/- 3% voxels in group I versus 16 +/- 4% in group II (NS). Cerebral blood flow values in eight brain regions followed the same hyperemia-hypoperfusion sequence as global cerebral blood flow, with no significant difference in regional values between groups. The global cerebral metabolic rate of oxygen, which ranged between 2.7 and 4.5 mL/100 cm3 per minute before arrest in both groups, was at 1 hour after arrest 1.8 +/- 0.3 mL in normothermic group I (n = 3) and 1.9 +/- 0.4 mL is still-hypothermic group II (n = 5); at 2 and 4 hours after arrest, it ranged between 1.2 and 4.2 mL in group I and between 1.2 and 2.6 mL in group II. CONCLUSIONS: After cardiac arrest, mild resuscitative hypothermia lasting 1 hour does not significantly affect patterns of cerebral blood flow and oxygen uptake. This suggests that different mechanisms may explain its mitigating effect on brain damage.

Animals↗

Three year longitudinal study for out-of-hospital cardiac arrest in Osaka Prefecture.

OBJECTIVE: To analyze the longitudinal changes in the treatment of out-of-hospital cardiac arrests. These analyses have focused on the time interval from the receipt of call until defibrillation of patients with ventricular fibrillation. DESIGN: Population-based, prospective longitudinal study according to the Utstein style. SETTING: Osaka Prefecture (population 8, 800, 000), served by 36 municipal fire and emergency departments. PATIENTS: Consecutive, out-of-hospital cardiac arrests occurring between May 1998 and April 2001. MAIN OUTCOME MEASURES: Change in the interval to defibrillation, and one-year survival from cardiac arrest. RESULTS: Of the 15,211 cases of confirmed cardiac arrests during the three years, resuscitation was attempted in 14,609 subjects. Of the 2957 cases of cardiac origin and witnessed by bystanders, 90 cases (3.0%) were alive 1 year following the episode. In 383 cases of defibrillation, the interval from receipt of call to defibrillation was evaluated annually. This interval decreased significantly during the three year course (14.5, 13.0, and 11.5 min expressed by the median), suggesting that this project to report the data of out-of-hospital arrests was an effective campaign for EMT. However, the outcome did not improve significantly during this period (3.0%, 2.6%, and 3.6% alive 1 year in witnessed arrests with cardiac etiology). This may be because the third year median duration of 11.5 min, is still insufficient to indicate a significant improvement in the outcome. CONCLUSIONS: This project to report the data of out-of-hospital cardiac arrest might have contributed to the reduction of the interval for defibrillation, as a campaign for the EMTs; although the decrease in this interval was still insufficient to result in a significant increase in the number of cases who are alive one year later.

Electric Countershock↗

Predictors of survival following cardiac arrest in patients undergoing noncardiac surgery: a study of 518,294 patients at a tertiary referral center.

BACKGROUND: The authors determined the incidence of cardiac arrest and predictors of survival following perioperative cardiac arrest in a large population of patients at a tertiary referral center. METHODS: Medical records of patients who experienced cardiac arrest in the perioperative period surrounding noncardiac surgery between January 1, 1990, and December 31, 2000, were reviewed. Logistic regression identified characteristics associated with immediate (>or= 1 h) and hospital survival, with P <or= 0.01 considered statistically significant. RESULTS: Cardiac arrest occurred in 223 of 518,294 anesthetics (4.3 per 10,000) during the study period. Frequency of arrest for patients receiving general anesthesia decreased over time (7.8 per 10,000 during 1990-1992; 3.2 per 10,000 during 1998-2000). The frequency of arrest during regional anesthesia (1.5 per 10,000) and monitored anesthesia care (0.7 per 10,000) remained consistent. Immediate survival after arrest was 46.6%, and hospital survival was 34.5%. Twenty-four patients (0.5 per 10,000) had cardiac arrest related primarily to anesthesia. From multivariate analysis, patients who experienced arrest due to bleeding were less likely to survive hospitalization (P = 0.001). Survival was also lower for patients who experienced arrest during nonstandard working hours (P = 0.006) and for patients who had protracted hypotension before arrest (P < 0.001). CONCLUSIONS: The overall frequency of arrest for patients receiving anesthesia decreased during the study period. Most arrests were not due to anesthesia-related causes, and most patients experiencing anesthesia-related arrest survived to hospital discharge. Although many factors determining survival may not be amenable to modification, the fact that arrests during nonregular working hours had worse outcomes may indicate that the availability of human resources influences survival.

Adolescent↗

Characteristics and outcome amongst young adults suffering from out-of-hospital cardiac arrest in whom cardiopulmonary resuscitation is attempted.

OBJECTIVES: Amongst patients suffering from out-of-hospital cardiac arrest, young adults represent a minority. However, these victims suffer from the catastrophe when they are in a very active phase of life and have a long life expectancy. This survey aims to describe young adults in Sweden who suffer from out-of-hospital cardiac arrest and in whom cardiopulmonary resuscitation (CPR) is attempted in terms of characteristics and outcome. DESIGN: Prospective and descriptive design. SUBJECTS AND METHODS: Young adults (18-35 years) who suffered from out-of-hospital cardiac arrest in whom CPR was attempted and who were included in the Swedish Cardiac Arrest Registry between 1990 and 2004. MAIN OUTCOME MEASURES: Survival to 1 month. RESULTS: In all, 1105 young adults (3.1% of all the patients in the registry) were included, of which 29% were females, 51% were nonwitnessed and 15% had a cardiac aetiology. Only 17% were found in ventricular fibrillation, 53% received bystander CPR. The overall survival to 1 month was 6.3%. High survival was found amongst patients found in ventricular fibrillation (20.8%) and those with a cardiac aetiology (14.8%). Ventricular fibrillation at the arrival of the rescue team remained an independent predictor of an increased chance of survival (odds ratio: 7.43; 95% confidence interval: 3.44-16.65). CONCLUSION: Amongst young adults suffering from out-of-hospital cardiac arrest and in whom CPR was attempted, a minority survived to 1 month. Subgroups with a higher survival could be defined (patients found in ventricular fibrillation and patients in whom there was a cardiac aetiology). However, only one independent predictor of an increased chance of survival could be demonstrated, i.e. ventricular fibrillation at the arrival of the rescue team.

Adolescent↗

Incidence of sudden cardiac arrest is higher in areas of low socioeconomic status: a prospective two year study in a large United States community.

BACKGROUND: A potential effect of socioeconomic status on occurrence of sudden cardiac arrest in the community is likely, but has not been evaluated fully. METHODS: All cases of sudden cardiac arrest in Multnomah County Oregon (population 660,486; February 2002-January 2004) were identified prospectively and categorized by census tract based on the address of residence and specific geographic location of occurrence of cardiac arrest. Each census tract was assigned to quartiles of median income, poverty level, median home value, and educational attainment. RESULTS: Of 714 cases (annual incidence 54 per 100,000), 697 (98%) had residential addresses that matched a county census tract successfully. For each socioeconomic status measure, the incidence of cardiac arrest was 30-80% higher in the lowest compared to the highest socioeconomic status census tracts. Annual incidence in census tracts in the lowest compared to the highest quartiles of median home value was 60.5 versus 35.1 per 100,000 (RR 1.7, 95% CI 1.4-2.2). This gradient was exaggerated significantly for age<65 years (34.5 versus 15.1 per 100,000, RR 2.3, 95% CI 1.6-3.3). Identical trends were observed for sudden cardiac arrest based on location, with 60% of all cases and 66% of cases age<65 years occurring in the two quartiles with lowest socioeconomic status. CONCLUSIONS: Low neighborhood socioeconomic status was associated with a significantly higher incidence of sudden cardiac arrest based on address of residence as well as location of cardiac arrest. For effective deployment of strategies for community-based prevention such as the automated external defibrillator, neighborhood socioeconomic status is likely to be an important consideration.

Adult↗

The long-term prognosis of patients with out-of-hospital cardiac arrest but no inducible ventricular tachycardia.

The long-term prognosis of patients successfully resuscitated from cardiac arrest who do not have acute precipitating factors and in whom ventricular arrhythmias cannot be induced during baseline electrophysiologic testing is controversial. The purpose of this investigation was to evaluate the long-term risk of recurrent sudden death and determine the clinical, angiographic, hemodynamic, and electrophysiologic predictors of recurrent cardiac arrest in such patients. Twenty-six (37%) of 71 consecutive patients with a single episode of aborted sudden death did not have inducible ventricular arrhythmias (less than 7 intraventricular responses) during baseline drug-free electrophysiologic study and they form the basis of this report. Their mean age was 54 +/- 13 (mean +/- SD) years and the left ventricular ejection fraction (LVEF) was 0.47 +/- 0.17. After a mean follow-up period of 16 months, 11 patients (42%) had a recurrent cardiac arrest (fatal in 10 patients). The actuarial incidence of recurrent cardiac arrest was 30 +/- 10% at 1 year and 55 +/- 13% at 3 years. Patients with LVEF less than or equal to 0.40 had a significantly higher occurrence of recurrent cardiac arrest than those with LVEF greater than 0.40 (p = 0.02; 1-year actuarial incidence of 57 +/- 17% versus 13 +/- 19%). Patients with recurrent sudden death had a significantly greater incidence of dilated cardiomyopathy (55% versus 7%; p = 0.02) and baseline frequent premature ventricular contractions (PVCs greater than 10/hr; 64% versus 17%, p = 0.036) or nonsustained ventricular tachycardia (36% versus 0%; p = 0.37) than patients without these characteristics.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Incidence of cardiac arrest: a neglected factor in evaluating survival rates.

STUDY OBJECTIVES: To add to our understanding of survival rates in out-of-hospital cardiac arrest studies, we examined the incidence of cardiac arrest in the published literature. We specifically estimated if incidence rates are uniform between communities and if any relationship exists between incidence and the reported survival rates. DESIGN: A retrospective study of nearly 100 cardiac arrest peer-reviewed articles from 1970 to 1989 was performed to identify reports that included rates for incidence and survival or provided sufficient data for the calculation of these rates. MEASUREMENTS AND MAIN RESULTS: We were able to obtain reported or calculated incidence and survival rates for 20 communities. Statistical analysis was performed to compare incidence rates between communities and examine the relationship across these 20 studies between incidence rates and reported survival rates. Incidence rates ranged significantly from 35.7 to 128.3 per 100,000, with a mean of 62. Survival rates ranged significantly from 1.6% to 20.7%. Incidence rates in these communities were negatively related to survival rates; that is, as the incidence rate increased, the survival rate decreased. We determined the regression curve that describes this inverse relationship. This nomogram can be used to identify survival/incidence rate combinations that are significantly above or below average. CONCLUSION: The marked variations in incidence and inverse relationship between incidence and survival could be due to true variation in risk among the populations reported (ie, some populations may be older or sicker than others). Also, different research methodologies may create artifactual differences among studies as standards for designing studies, terminology, and reporting data have not been uniform. Therefore, these findings may reflect methodological differences and true epidemiological differences among communities. Future reports should include a method, such as an incidence/survival nomogram, to analyze survival rates while taking into account the community incidence rate of cardiac arrest. Further analysis of incidence and survival is necessary to improve intersystem comparisons, a prerequisite to sound decisions about cardiac arrest treatment, health policy, and allocation of resources.

Heart Arrest↗

Oxidant injury occurs rapidly after cardiac arrest, cardiopulmonary resuscitation, and reperfusion.

OBJECTIVE: Investigations conducted in cellular models show that reperfusion of ischemic tissue is associated with a burst of reactive oxidant species within minutes after reperfusion. Oxidant injury may play a role in the poor outcome typical of people resuscitated from cardiac arrest. The objective of the present study was to determine the presence and timing of oxidant injury in an in vivo model of cardiac arrest. DESIGN: Randomized controlled. SETTING: University medical center laboratory. SUBJECTS: Domestic swine. INTERVENTIONS: We evaluated oxidant injury during and after 8 mins of cardiac arrest using a gas chromatography/mass spectrometry F2-isoprostane assay and compared these results with a matched control group. MEASUREMENTS AND MAIN RESULTS: Baseline mean arterial, venous, and brain tissue F2-isoprostane levels were not significantly different when the cardiac arrest group was compared with the control group. However, in the group subjected to cardiac arrest and cardiopulmonary resuscitation we found significant (p < .0006) two- to three-fold increases in venous and arterial F2-isoprostane levels, which peaked between 15 and 30 mins after reperfusion and returned to baseline within 90 mins (p < .0006). Overall mean (+/- SE) brain tissue F2-isoprostane levels increased significantly to 370 +/- 60 vs. 140 +/- 60 ng/g tissue in the cardiac arrest group compared with the control group (p = .026). CONCLUSION: This study shows that F2-isoprostane measurement could be used to assess oxidant injury in an animal model of cardiac arrest and that oxidant injury occurs rapidly after cardiac arrest and reperfusion.

Animals↗

The influence of chronic prearrest health conditions on mortality and functional neurological recovery in cardiac arrest survivors.

PURPOSE: To study the impact of chronic prearrest health conditions on mortality and neurological recovery in patients after witnessed cardiac arrest and primary successful resuscitation. PATIENTS AND METHODS: The study was set in the community of Vienna, Austria. Data concerning cardiopulmonary resuscitation of adult patients who survived a witnessed cardiac arrest were collected according to an internationally recommended protocol (Utstein-Style). Chronic prearrest health conditions and New York Heart Association (NYHA) functional classes were evaluated. All patients were followed up for 6 months after the event or death. Adverse outcome was defined as death or severe neurological impairment. A forward stepwise logistic regression model was applied to assess the impact of pre-arrest morbidity on unfavorable outcome, expressed as odds ratio (OR) with 95% confidence intervals (CI). RESULTS: Of 411 patients, 269 (66%) had one or more of the following pre-arrest diseases: coronary heart disease (45%), hypertension (26%), congestive heart failure (20%), diabetes mellitus (14%), chronic pulmonary disease (6%), and cerebrovascular disease (5%). In 22% a NYHA class of III or IV was present before cardiac arrest. At 6-month follow-up, 161 (40%) of the patients were alive with favorable neurological recovery; overall mortality was 57% (n = 233). Increasing NYHA classes (OR 1.4 per NYHA class increase; CI 1.1 to 1.7) and increasing age were independent predictors of adverse outcome (OR 1.03 per 10-year increase; CI 1.01 to 1.05), as were durations of cardiac arrest (OR 1.10 per 5-minute increase; CI 1.07 to 1.12) and the presence of ventricular fibrillation or tachycardia (OR 0.3; CI 0.2 to 0.5). The remaining health conditions, as listed above, were not independently associated with outcome. CONCLUSIONS: A large proportion of patients with cardiac arrest had chronic diseases before the event. The presence of impaired functional performance in patients with structural heart disease increased unfavorable outcome within 6 months in primary cardiac arrest survivors. However, the impact of chronic prearrest conditions on outcome seems to be very small, and should not influence decisions whether to withhold or withdraw therapy.

Aged↗

Bradycardia and asystolic cardiac arrest during spinal anaesthesia: a report of five cases.

Sudden, severe bradycardia/asystolic cardiac arrest are considered infrequent, but are certainly the most serious complications of spinal anaesthesia. We report four cases of primary asystole and one of severe bradycardia in young to middle-aged, healthy patients scheduled for minor surgery at the day surgery unit. Bradycardia/asystole were not related to respiratory depression or hypoxaemia/hypercarbia; they occurred at different time intervals after the onset of spinal anaesthesia (10-70 min) and, apparently, were not dependent on the level of sensory block, which varied between T3 and T8. One patient was nauseated seconds before the asystole, otherwise there was no warning signs. All the patients were easily resuscitated with the prompt administration of atropine and ephedrine and, in the case of cardiac arrest, cardiac massage and ventilation with oxygen. One patient was treated with a small dose of adrenaline. Four patients had the surgery, as planned; one had the surgery postponed. All the patients were discharged from hospital in good health and did not suffer any sequelae.

Adult↗

Improved out-of-hospital cardiac arrest survival through the inexpensive optimization of an existing defibrillation program: OPALS study phase II. Ontario Prehospital Advanced Life Support.

CONTEXT: Survival rates for out-of-hospital cardiac arrest are low; published survival rates in Ontario are only 2.5%. This study represents phase II of the Ontario Prehospital Advanced Life Support (OPALS) study, which is designed to systematically evaluate the effectiveness and efficiency of various prehospital interventions for patients with cardiac arrest, trauma, and critical illnesses. OBJECTIVE: To assess the impact on out-of-hospital cardiac arrest survival of the implementation of a rapid defibrillation program in a large multicenter emergency medical services (EMS) system with existing basic life support and defibrillation (BLS-D) level of care. DESIGN: Controlled clinical trial comparing survival for 36 months before (phase I) and 12 months after (phase II) system optimization. SETTING: Nineteen urban and suburban Ontario communities (populations ranging from 16 000 to 750 000 [total, 2.7 million]). PATIENTS: All patients who had out-of-hospital cardiac arrest in the study communities for whom resuscitation was attempted by emergency responders. INTERVENTIONS: Study communities optimized their EMS systems to achieve the target response interval from when a call was received until a vehicle stopped with a defibrillator of 8 minutes or less for 90% of cardiac arrest cases. Working both locally and provincially, communities implemented multiple measures, including defibrillation by firefighters, base paging, tiered response agreements with fire departments, continuous quality improvement for response intervals, and province-wide revision and implementation of standard dispatch policies. All response times were obtained from a central dispatch system. MAIN OUTCOME MEASURE: Survival to hospital discharge. RESULTS: The 4690 cardiac arrest patients studied in phase I and the 1641 in phase II were similar for all clinical and demographic characteristics, including age, sex, witnessed status, rhythm, and receipt of bystander cardiopulmonary resuscitation. The proportion of cases meeting the 8-minute response criterion improved (76.7% vs 92.5%; P<.001) as did most median response intervals. Overall survival to hospital discharge for all rhythm groups combined improved from 3.9% to 5.2 % (P = .03). The 33% relative increase in survival represents an additional 21 lives saved each year in the study communities (approximately 1 life per 120000 residents). The charges were estimated to be US $46900 per life saved for establishing the rapid defibrillation program and US $2400 per life saved annually for maintaining the program. CONCLUSION: An inexpensive, multifaceted system optimization approach to rapid defibrillation can lead to significant improvements in survival after cardiac arrest in a large BLS-D EMS system.

Aged↗

The three-phase model of cardiac arrest as applied to ventricular fibrillation in a large, urban emergency medical services system.

BACKGROUND: Cardiac arrest is responsible for significant morbidity and mortality, with consistently poor outcomes despite the rapid availability of prehospital personnel for defibrillation attempts in patients with ventricular fibrillation (VF). Recent evidence suggests a period of cardiopulmonary resuscitation (CPR) prior to defibrillation attempts may improve outcomes in patients with moderate time since collapse (4-10 min). OBJECTIVES: To determine cardiac arrest outcomes in our community and explore the relationship between time since collapse, performance of bystander CPR, and survival. METHODS: Non-traumatic cardiac arrest data were collected prospectively over an 18-month period. Patients were excluded for: age <18 years, a "Do Not Attempt Resuscitation" (DNAR) directive, determination of a non-cardiac etiology for arrest, and an initially recorded rhythm other than VF. Patients were stratified by time since collapse (<4, 4-10, > 10 min, and unknown) and compared with regard to survival and neurological outcome. In addition, patients with and without bystander CPR were compared with regard to survival. RESULTS: : A total of 1141 adult non-traumatic cardiac arrest victims were identified over the 18-month study period. This included 272 patients with VF as the initially recorded rhythm. Of these, 185 had a suspected cardiac etiology for the arrest; survival to hospital discharge was 15% in this group, with 82% of these having a good outcome or only moderate disability. Survival was highest among patients with time since collapse of less than 4 min and decreased with increasing time since collapse. There were no survivors among patients with time since collapse greater than 10 min. Among patients with time since collapse of 4 min or longer, survival was significantly higher with the performance of bystander CPR; there was no survival advantage to bystander CPR among patients with time since collapse less than 4 min. CONCLUSIONS: The performance of bystander CPR prior to defibrillation by EMS personnel is associated with improved survival among patients with time since collapse longer than 4 min but not less than 4 min. These data are consistent with the three-phase model of cardiac arrest.

Aged↗