Sudden death from cardiac causes, often due to ventricular fibrillation, claims at least 250,000 persons annually in the United States.
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The American Heart Association guidelines for advanced ...cardiac life support state that antiarrhythmic medications are “acceptable, probably helpful” for the treatment of ventricular fibrillation or pulseless ventricular tachycardia that persists after three or more shocks from an external defibrillator (often called “shock-refractory” ventricular fibrillation or tachycardia).
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This guarded recommendation reflects the limited evidence supporting the use of these agents, none of which have been convincingly demonstrated to improve the success of attempted resuscitation after cardiac arrest.
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CONTEXT Use of automated external defibrillators (AEDs) by
first arriving emergency medical technicians (EMTs) is advocated to
improve the outcome for out-of-hospital ventricular fibrillation (VF).
...However, adding AEDs to the emergency medical system in Seattle, Wash,
did not improve survival. Studies in animals have shown improved
outcomes when cardiopulmonary resuscitation (CPR) was administered
prior to an initial shock for VF of several minutes' duration. OBJECTIVE To evaluate the effects of providing 90 seconds of CPR
to persons with out-of-hospital VF prior to delivery of a shock by
first-arriving EMTs. DESIGN Observational, prospectively defined, population-based
study with 42 months of preintervention analysis (July 1, 1990-December
31, 1993) and 36 months of postintervention analysis (January 1,
1994-December 31, 1996). SETTING Seattle fire department–based, 2-tiered emergency medical
system. PARTICIPANTS A total of 639 patients treated for out-of-hospital
VF before the intervention and 478 after the intervention. INTERVENTION Modification of the protocol for use of AEDs,
emphasizing approximately 90 seconds of CPR prior to delivery of a
shock. MAIN OUTCOME MEASURES Survival and neurologic status at hospital
discharge determined by retrospective chart review as a function of
early (<4 minutes) and later (≥4 minutes) response intervals. RESULTS Survival improved from 24% (155/639) to 30% (142/478)
(P=.04). That benefit was predominantly in
patients for whom the initial response interval was 4 minutes or longer
(survival, 17% 56/321 before vs 27% 60/220 after;
P = .01). In a multivariate logistic model, adjusting for
differences in patient and resuscitation factors between the periods,
the protocol intervention was estimated to improve survival
significantly (odds ratio, 1.42; 95% confidence interval, 1.07-1.90;
P = .02). Overall, the proportion of victims who survived
with favorable neurologic recovery increased from 17% (106/634) to
23% (109/474) (P = .01). Among survivors, the proportion
having favorable neurologic function at hospital discharge increased
from 71% (106/150) to 79% (109/138) (P<.11). CONCLUSION The routine provision of approximately 90 seconds of
CPR prior to use of AED was associated with increased survival when
response intervals were 4 minutes or longer.
To evaluate the feasibility, safety, and efficacy of interventions aimed at improving neurologic outcome after cardiac arrest.
The authors conducted a double-blind, placebo-controlled, randomized ...clinical trial with factorial design to see if magnesium, diazepam, or both, when given immediately following resuscitation from out-of-hospital cardiac arrest, would increase the proportion of patients awakening, defined as following commands or having comprehensible speech. If the patient regained a systolic blood pressure of at least 90 mm Hg and had not awakened, paramedics injected IV two syringes stored in a sealed kit. The first always contained either 2 g magnesium sulfate (M) or placebo (P); the second contained either 10 mg diazepam (D) or P. Awakening at any time by 3 months was determined by record review, and independence at 3 months was determined by telephone calls. Over 30 months, 300 patients were randomized in balanced blocks of 4, 75 each to MD, MP, PD, or PP. The study was conducted under waiver of consent.
Despite the design, the four treatment groups differed on baseline variables collected before randomization. Percent awake by 3 months for each group were: MD, 29.3%; MP, 46.7%; PD, 30.7%; PP, 37.3%. Percent independent at 3 months were: MD, 17.3%; MP, 34.7%; PD, 17.3%; PP, 25.3%. Significant interactions were lacking. After adjusting for baseline imbalances, none of these differences was significant, and no adverse effects were identified.
Neither magnesium nor diazepam significantly improved neurologic outcome from cardiac arrest.
Abstract Objective Conduct of emergency research under waiver of consent produces special challenges. Moreover, the act of performing research may have unintended effects, potentially beneficial or ...detrimental. The Dispatcher-Assisted Randomized Trial (DART) was designed to compare 2 types of dispatcher cardiopulmonary (CPR) instruction, but not intended to affect the proportion of arrest victims that received bystander CPR. We sought to determine whether odds of receiving bystander CPR were higher during DART than during the periods before and after. Methods We conducted an observational cohort study of 8626 adults who suffered non-traumatic out-of-hospital cardiac arrest prior to emergency medical services (EMS) arrival in greater King County, Washington, between January 1, 1999, and December 31, 2011. Bystander CPR status was assessed through review of dispatch recordings and EMS reports to classify any bystander CPR (any B-CPR), and further categorized as bystander CPR with or without dispatcher assistance (DA-CPR and B-CPR, no DA). We used multivariable logistic regression to evaluate odds of B-CPR before, during, and after DART. Results The proportions receiving any B-CPR were 52% before DART (1817/3468), 59% during DART (2093/3527), and 54% after DART (885/1631). Compared to the period before DART, odds of receiving any B-CPR were higher during DART (OR = 1.35, 95% CI = 1.23–1.49), but no different after (OR = 1.10, 0.98–1.24). Compared to the before period, odds of DA-CPR were higher during DART (OR = 1.79, 1.59–2.02) but no different after (OR = 0.94, 0.80–1.10). Conclusions Odds of bystander CPR were higher during the trial, an increase related to higher likelihood of DA-CPR. The finding suggests a possible indirect community-wide benefit due to the interventional trial.
The incidence of sudden cardiac death is roughly 3 times greater in men than in women. However, in patients treated for out-of-hospital cardiac arrest, the relationships between sex and survival ...after adjustment for age and cardiac rhythm are unclear.
In this retrospective cohort study, we examined 7069 men and 2582 women who were treated for out-of-hospital cardiac arrest in Seattle and suburban King County between 1990 and 1998. We compared successful prehospital resuscitation (hospital admission) and survival from event to discharge in men and women. Women had markedly reduced rates of ventricular fibrillation (VF), slightly older age, fewer witnessed arrests, and fewer arrests in public locations than men. Although their unadjusted resuscitation rate was lower (29% versus 32%, P<0.0001), women had a greater likelihood of resuscitation than men after adjustment for VF (odds ratio OR 1.13; 95% confidence interval CI, 1.03 to 1.25) and after adjustment for VF plus additional factors (OR, 1.27; 95% CI, 1.14 to 1.41). The difference in resuscitation rates between men and women decreased as they aged (test for trend, P<0.0001). Unadjusted survival rates were also lower in women than in men (11% versus 15%, P<0.0001). Women had similar survival after adjustment for VF (OR, 0.97; 95% CI, 0.85 to 1.11) and after adjustment for VF plus additional factors (OR, 1.09; 95% CI, 0.93 to 1.27).
The lower unadjusted resuscitation and survival rates observed in women were primarily due to women's lower incidence of VF, a relatively favorable cardiac rhythm. After adjustment for VF and other factors, women had higher resuscitation rates than men, but similar rates of survival from event to discharge.
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.
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.
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.
Patterns of temporal variation of cardiac arrests may be important for understanding mechanisms leading to the onset of acute cardiovascular disorders. Previous studies reported diurnal variation of ...the onset of cardiac arrests, with high incidence in the morning and in the evening, lack of daily variation during the week, and some seasonal variation. The association between the time of day and recurrent cardiac arrests has not been previously examined.
We explored temporal variation in 6603 out-of-hospital cardiac arrests attended by the Seattle Fire Department. The data exhibit diurnal variation, with a low incidence at night and two peaks of approximately the same size (at 8 to 11 AM and 4 to 7 PM). The evening peak is attributed primarily to the patients found in ventricular fibrillation, whereas arrests that show other rhythms exhibit mainly a morning peak. Cardiac arrests associated with survival have more pronounced diurnal variation than episodes in which survival did not occur. This difference persists after adjustment for rhythm. For 597 patients who had at least two separate cardiac arrests, we found no overall association between the times of day of the recurrent arrests. For women, however, the times of day of the first and second arrests were closer to each other than one would expect if the times were entirely unrelated.
Cardiac arrests do not occur randomly during the day, but rather follow certain periodic patterns. These patterns are probably associated with patterns of daily activities. The hypothesis that cardiac arrests are triggered by a person's activity rather than by some underlying characteristics of his or her disease is supported by the lack of association between the times of the first and second arrests in the patients with recurrent arrests.
Background Patterns of temporal variation of cardiac arrests may be important for understanding mechanisms leading to the onset of acute cardiovascular disorders. Previous studies have reported ...diurnal variation of the onset of cardiac arrests, with high incidence in the morning and in the evening, lack of daily variation during the week, and some seasonal variation.
Methods and Results We explored weekly and yearly (seasonal) temporal variation in 6603 out-of-hospital cardiac arrests attended by the Seattle Fire Department. We observed daily variation that peaks on Monday and seasonal variation that peaks in the winter.
Conclusions Cardiac arrests do not occur randomly during the week or year but follow certain periodic patterns. These patterns are probably associated with patterns of activities. (Am Heart J 1999;137:512-5.)
Out-of-hospital sudden cardiac arrest is a key area in which to study the dual problem of the poorer health status of minority populations and their poorer access to the health care system. We ...proposed to examine the relationship between race (Black/White) and survival.
We determined the incidence and outcome of cardiac arrests in Seattle for which medical assistance was requested.
Over a 26-month period, the age-adjusted incidence of out-of-hospital cardiac arrest was twice as great in Blacks than in Whites (3.4 vs 1.6 per 1000 aged 20 and over). The initial resuscitation rate was markedly poorer in the Black victims (17.1% vs 40.7%), and rates of survival to hospital discharge were also lower in Blacks (9.4% vs 17.1%). Both effective initial resuscitation and survival were significantly related to White race following adjustment for other covariates.
The differences in outcomes were not fully explained by features of the collapse or relevant service factors. Possible explanations include delays in instituting therapy, less bystander-initiated cardiopulmonary resuscitation, poorer levels of health, and differences in the underlying cardiac disorders.
The automatic external defibrillator is a simple device that can be used by nonprofessional rescuers to treat cardiac arrest. In 1287 consecutive patients with out-of-hospital cardiac arrest, we ...assessed the results of initial treatment with this device by firefighters who arrived first at the scene, as compared with the results of standard defibrillation administered by paramedics who arrived slightly after the firefighters. Of 276 patients who were initially treated by firefighters using the automatic defibrillator, 84 (30 percent) survived to hospital discharge (expected rate according to a logistic model, 17 percent; P less than 0.001), as compared with 44 (19 percent) of 228 patients when fire-fighters delivered only basic cardiopulmonary resuscitation and the first defibrillation was performed after the arrival of the paramedic team. Few patients with conditions other than ventricular fibrillation survived. In a multivariate analysis of characteristics that influenced survival after ventricular fibrillation, a better survival rate was related to a witnessed collapse (odds ratio, 3.9; 95 percent confidence interval, 2.0 to 7.6), younger age (odds ratio, 1.2; 95 percent confidence interval, 1.0 to 1.4), the presence of "coarse" (higher-amplitude) fibrillation (odds ratio, 4.2; 95 percent confidence interval, 1.6 to 11.0), a shorter response time for paramedics (odds ratio, 1.4; 95 percent confidence interval, 1.0 to 2.1), and initial treatment by firefighters using an automatic external defibrillator (odds ratio, 1.8; 95 percent confidence interval, 1.1 to 2.9). These findings support the widespread use of the automatic external defibrillator as an important part of the treatment of out-of-hospital cardiac arrest, although the overall impact of the use of this device on community survival rates is still uncertain.
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