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Out-of-hospital cardiac arrest (OHCA), with its high fatality rate, is a significant public health issue. The aetiology of OHCA is reviewed, and management strategies are discussed, including the "chain of survival", the Utstein method of data collection, and recent developments in advanced cardiac life support emphasising defibrillation.
This study demonstrates the effect of different denominators on the survival rate from out-of-hospital cardiac arrest. We retrospectively analyzed data from a cardiac arrest surveillance system in King County, Washington during the years 1976 to 1988, and calculated survival rates using eight different definitions of denominators. The eight survival rates ranged from 16% to 49% discharge from hospital. The denominator for the lowest survival rate included all cases of cardiac arrest for whom emergency medical services personnel started cardiopulmonary resuscitation. The denominator for the highest survival rate included: all cases of presumed cardiac etiology; first recorded rhythm was ventricular fibrillation; collapse witnessed; cardiopulmonary resuscitation started by bystanders within 4 minutes; and definitive care provided within 8 minutes. The definition of cases included in the denominator can dramatically effect the resultant survival rate. There must be national and international agreement about definitions of denominators for valid cross community comparisons.
In a rat model of cardiac arrest and resuscitation, [(14)C]-iodoantipyrene (IAP) autoradiography was used to measure the regional variations in cerebral blood flow 15 and 60 min after reperfusion. The purpose of this study was to investigate the hypothesis that the inhibition of the Na+/H+ antiporter with methyl isobutyl amiloride (MIA) would decrease postischemic pericapillary cytotoxic edema and, therefore, improve vascular perfusion dynamics. Vehicle-treated rats responded to cardiac arrest and resuscitation as expected with initial hyperemia after 15 min of reperfusion, except for thalamic and midbrain structures which were hypoperfused. All brain structures were perfused at half the baseline blood flow at 60 min after resuscitation, and the residual blood flow in each region was proportional to the baseline flow of each region. MIA treatment was associated with decreased blood flow in every region examined at both 15 min and 60 min of reperfusion. No hyperemia was observed at 15 min in any region after MIA treatment. Sixty minutes after resuscitation in MIA-treated rats, all structures were hypoperfused (to 25+/-7% of baseline, 48+/-8% of vehicle-treated rats). These effects are unlikely to be due to prevention of cytotoxic edema, but may be due to MIA protection of capillary endothelium by prevention of neutrophil activation.
OBJECTIVE: Recent data suggest that using vasopressin in combination with epinephrine (adrenaline) may improve treatment of out-of-hospital cardiac arrest. This study examined local experience with the combination of epinephrine and vasopressin administration. METHODS: Data were obtained from an urban, municipal emergency medical service that does not include vasopressin in its formulary. A physician is dispatched to the scene of all cardiac arrest patients treated by this system. Vasopressin could be administered in addition to epinephrine to subjects with out-of-hospital cardiac arrest by the on-scene physician. Demographic information, drug administration and return of pulses were abstracted from patient care records for a 1-year interval. Multivariate logistic regression was used to assess the relationship between vasopressin use and outcomes. RESULTS: During the study period, data were available for 298 subjects receiving epinephrine-only (n=231, 78%), a combination of 40 IU vasopressin and epinephrine (n=37, 12%) or no vasopressor drugs (n=30, 10%). Among patients receiving vasopressor drugs, pulse was restored for 74 subjects (28%), and 56 subjects (21%) had a pulse on arrival at the hospital. Return of pulses was associated with witnessed collapse, bystander CPR, and an initial ECG rhythm of ventricular fibrillation or tachycardia. Subjects receiving vasopressin and epinephrine were more likely to have a return of pulses during the resuscitation (LR: 2.73; 95% CI: 1.24, 6.03) and at hospital arrival (3.85; 1.71, 8.65) than subjects treated with epinephrine alone. CONCLUSIONS: There is an association between using vasopressin in combination with epinephrine and restoration of circulation after out-of-hospital cardiac arrest.
The use of epinephrine in cardiac arrest remains an area of continuing controversy. This study was undertaken to characterize the effect of endogenous and exogenous epinephrine on plasma epinephrine levels, and the relationship between plasma epinephrine and norepinephrine and mean arterial pressure and diastolic arterial pressure. Nineteen young swine were anesthetized with ketamine and alpha-chloralose and instrumented with arterial and central venous lines. Ventricular fibrillation was induced by pacemaker. At 5 min post arrest cardiopulmonary resuscitation (CPR) was begun with a mechanical resuscitator. Animals were randomized to receive either saline placebo (n = 9), 0.01 mg/kg epinephrine (n = 5) or 0.1 mg/kg epinephrine (n = 5) via the central venous line. Plasma was drawn for high pressure liquid chromatographic analysis of catecholamines every 2 min. The resuscitation was carried on for 30 min after the arrest. Plasma epinephrine levels differed significantly between treated subjects and controls, as did mean arterial pressure and diastolic arterial pressure. There was a correlation between both mean arterial pressure and diastolic arterial pressure with plasma epinephrine and log epinephrine, but no correlation with plasma norepinephrine. The two doses of epinephrine did not differ in the degree to which they elevated the mean arterial pressure and diastolic pressure. We conclude that the endogenous catecholamine response to cardiac arrest while producing norepinephrine and epinephrine levels many times greater than those in the resting animal, is not sufficient to maintain blood pressure. There is a strong correlation between blood pressure and the log of the plasma epinephrine concentration, but epinephrine concentration alone does not solely account for changes in blood pressure during arrest.
BACKGROUND: The availability of implantable cardioverter-defibrillators (ICD) that are capable of antitachycardia pacing may lead to an increased use of ICDs in patients with haemodynamically tolerated ventricular tachycardia without a history of cardiac arrest. The frequency of potentially life-threatening fast ventricular tachycardias (cycle length < 250 ms) was investigated in patients who had a third generation ICD with endocardial leads implanted because they had haemodynamically tolerated ventricular tachycardia without a history of cardiac arrest. METHODS: Between January 1990 and October 1993, 50 patients (age (mean (SD)) 60 (11); ejection fraction 39 (16)%; 82% with coronary artery disease and 8% with dilated cardiomyopathy) with haemodynamically tolerated ventricular tachycardia (cycle length (mean (SD)) 348 (60) ms; range 250-500 ms) and without a history of cardiac arrest were treated with third generation ICDs that were capable of antitachycardia pacing. Fast ventricular tachycardia had been induced in 14 (28%) during baseline electrophysiological study. The benefit of ICD treatment was estimated as the difference between total mortality and the occurrence of fast ventricular tachycardia that would have been fatal if it had not been terminated. RESULTS: During follow up of 17 (12) months, 33 patients (66%) had a total of 3861 episodes of ventricular tachycardia. 91% of these episodes were terminated by antitachycardia pacing. 11 patients (22%) had episodes of potentially life-threatening fast ventricular tachycardia and 3 of these also had inducible fast ventricular tachycardia. One patient died suddenly 27 months after implantation. The difference between survival without fast ventricular tachycardia and total mortality was 9%, 12%, 27%, and 27% at 6, 12, 18, and 24 months, respectively. CONCLUSIONS: About a fifth of patients who had been given an ICD to treat haemodynamically tolerated ventricular tachycardia and who had no history of cardiac arrest experienced fast ventricular tachycardia during follow up requiring immediate cardioversion. Prospective studies are needed to investigate whether the prognosis of patients with a history of haemodynamically tolerated ventricular tachycardia without cardiac arrest is improved by ICD therapy.
Sudden cardiac death accounts for two thirds of death due to coronary artery disease. Advanced cardiac life support can now be brought directly to patients with out-of-hospital cardiac arrest, and in this country, as many as 30% of such patients can be discharged from the hospital annually. Certain clinical and resuscitation-related factors are predictive of mortality and morbidity. The best clinical predictors of long-term survival are absence of previous history of myocardial infarction, lack of congestive heart failure during hospitalization, and age less than 60 years. Resuscitation-related predictors of long-term survival are a short time collapse to cardiopulmonary resuscitation (CPR), and a short time from collapse to CPR combined with a short time to provision of definitive care. The majority of cardiac arrest survivors are able to resume previous levels of function.
The ability to predict outcomes of cardiac arrest before starting cardiopulmonary resuscitation (CPR) would be useful for discussions of resuscitation with elders and their families. We thought CPR outcome might be dependent on the severity of pre-existing illnesses. The APACHE II is a severity-of-illness (SOI) scale based, in part, on physiologic parameters whereby points are given for degree of deviation from normal. Additionally, up to six points are given for increased age. We hypothesized that (1) patients with the highest APACHE II would be least likely to survive, and (2) because of the blunted physiologic responsiveness, the APACHE II would underestimate the SOI of elderly patients who were sufficiently ill to have a cardiac arrest. A retrospective study of 172 arrests was carried out to evaluate these hypotheses. For the young cohort (n = 126; age, < 70; mean age, 59 +/- 8), mean admission APACHE II was 16.5 +/- 7.9 and pre-arrest APACHE II regression analysis.2+ carried out with both APACHE II scores and factors previously correlated with CPR outcome. Witnessed arrests and those requiring a low number of medications were most likely to result in immediate success (restoration of blood pressure) and in a live discharge. APACHE II score (24 h pre-arrest) was associated with live discharge in the regression analysis.(ABSTRACT TRUNCATED AT 250 WORDS)
Preventing cardiac arrests requires constant vigilance on the part of the entire perioperative team. In the preoperative phase, physicians must make careful patient selections based on the patients' risk factors, and cancel the cases or admit the patients if problems are found. In the intraoperative phase, the anesthesia personnel must carefully monitor vital signs, observe tissue perfusion, replace fluids, position the patient to maximize vital functions, and carefully select the anesthetic agents. In the postoperative phase, nurses must carefully observe and monitor the patient, especially high-risk patients, and take any necessary precautions. They must also explain instructions to the patient regarding complications after discharge. Although a manager may establish careful patient selection criteria, the day may come when the staff members must respond to a cardiac arrest in the ambulatory surgery unit. When it does, management of the patient must be the first priority. The staff members must correctly diagnose the problem, send for assistance, perform CPR, mobilize equipment, oxygen, and medications, control traffic, document interventions, and record patient responses. In an ambulatory setting, there is a high probability that family members or friends will be with the patient. A nurse should be delegated to take them to a quiet area away from the immediate crisis, and provide information and emotional support. Frequent reports will help them cope with the crisis. Public awareness and knowledge about CPR has greatly increased since it was first used in 1960. By 1977, some 12 million Americans had been CPR-trained and some 53 million more were awaiting training.(ABSTRACT TRUNCATED AT 250 WORDS)
Neurologic impairment remains a serious consequence of cardiac arrest. While current investigations are difficult to compare due to their lack of standardization, our understanding of the pathophysiology of CNS ischemia has been greatly increased. Ion fluxes, especially K and Ca, may contribute to injury by initiating a cascade of events culminating in free fatty acid, prostaglandin, and free radical formation, with their related pathogenetic potential. Treatment measures currently consist of CPR (although disagreement exists as to which form of CPR), standard supportive measures, and attention to intracranial pressure control. There is some experimental evidence to support the use of calcium channel-blockers, phenytoin, prostaglandin inhibitors, and free-radical scavengers or inhibitors; however, no human trials have been performed. Steroids and barbiturates have been investigated in human trials and do not appear to be efficacious in ameliorating CNS injury after cardiac arrest.
Non-invasive and real-time measures of neurological status after cardiac arrest are needed to be able to make an early determination of the postresuscitative outcome. We investigated whether the bispectral index (BIS) predicts the postresuscitative outcome in 10 patients with out-of-hospital cardiac arrest. We measured the BIS after return of spontaneous circulation (ROSC) in the emergency room and on admission to the intensive care unit (ICU). We determined the Glasgow Coma Scale (GCS) on admission to the emergency room and the ICU and the Glasgow Outcome Scale (GOS) on discharge from the ICU. The BIS increased after about 30 min of ROSC or reached a plateau in patients rated as achieving a good recovery or moderate disability, but it did not increase to >80 in patients rated as being in a permanent vegetative state/dead. The GCS on admission to the ICU was the same as that on admission to the emergency room. The BIS values were significantly lower in the nonsurviving group than in the surviving group. There was a positive correlation between the BIS on admission to the ICU and the GOS on discharge from the ICU. The BIS can thus be used to predict the postresuscitative outcome of patients with out-of-hospital cardiac arrest.
Twenty children who were successfully resuscitated after cardiac arrest (CA) were retrospectively studied to examine the hypothesis that children with CA may have a worse neurological outcome in hot weather than in cold weather. Of 7 children with CA in the cold season (atmospheric temperature < 14 degrees C), 4 in the warm season (14-24 degrees C) and 9 in the hot season (> 24 degrees C), 5 (71%), 2 (50%), and 1 (11%), respectively, recovered consciousness (P < 0.05). Postresuscitative hyperthermia tended to be frequently observed in the group of children who suffered CA in the hot season, and it appeared to be associated with neurological damage. This preliminary study suggests that the neurological outcome of children with CA changes with the seasons, with a worse neurological outcome for CA in hot weather than in cold weather. A prospective study is required to determine whether, in a hot season or area, cooling of pediatric cardiac arrest victims during cardiopulmonary resuscitation on the scene improves the neurological outcome.
Our objective was to evaluate a colorimetric end-tidal CO2 detector in a canine model for pediatric cardiac arrest. In a prospective unblinded study, cardiac arrest was induced in 11 anesthetized and paralyzed puppies, weighing 5.0 to 6.1 kg, by clamping the endotracheal tube (ETT) and discontinuing mechanical ventilation. During cardiopulmonary resuscitation (CPR), the detector and the capnometer were connected between the ETT and ventilator tubing. Color shades on the detector ranged from 1 (purple) to 6 (yellow) corresponding to increasing concentrations of CO2. End-tidal CO2 concentrations as indicated by detector color and capnometric reading were monitored and recorded throughout the study. The results showed that there was a significant correlation between the detector color score and capnometric readings (P < 0.001). A sudden rise in end-tidal CO2 indicated by both the capnometer and the detector occurred at return of spontaneous circulation (ROSC) in seven or < 1 minute before ROSC in four animals. This association was significant (P = 0.0009). We conclude that these results demonstrate that, in a canine model for pediatric cardiac arrest, the detector readings correlate with capnometry during CPR and indicate ROSC.
STUDY OBJECTIVE: To evaluate the effectiveness of transcutaneous cardiac pacing in out-of-hospital treatment of cardiac arrests in pediatric patients. DESIGN: We describe the outcome of patients treated during a prospective trial of transcutaneous cardiac pacing in the field. We compare their outcome with that of out-of-hospital arrests in submersion patients who were not paced. We identified patients from Seattle and King County Emergency Medical Services reports, hospitals, and medical examiner's registries. MEASUREMENTS AND MAIN RESULTS: Nine patients in cardiac arrest caused by drowning (six) and sudden infant death syndrome (three) were paced in the field. All were less than 6 years old. The one survivor was severely neurologically impaired and died six months later. Transcutaneous cardiac pacing produced electrical capture in two patients but no detectable pulse or blood pressure. Ten submersion patients less than 6 years old in cardiac arrest were not paced. One survived, with mild neurologic impairment at hospital discharge. CONCLUSION: Transcutaneous cardiac pacing was not effective and was not associated with improved survival.
Antiarrhythmic drugs may be used as primary therapy to prevent recurrent cardiac arrest or as adjunctive treatment in patients given an implantable cardioverter defibrillator. In the latter instance, drugs are given to suppress nonlethal arrhythmias that are capable of initiating defibrillator discharge or to slow and/or decrease the number of episodes of sustained ventricular tachyarrhythmias. When used as primary therapy, drug efficacy should be judged by nonempirical methods, preferably serial electrophysiological testing. Although no study has compared noninvasive with invasive testing to determine antiarrhythmic drug effectiveness in a substantial number of cardiac arrest survivors, several investigations have demonstrated that electrophysiological testing is useful for this purpose. One important limitation of serial electrophysiological testing is that nearly 40% of cardiac arrest survivors do not have a sustained ventricular tachyarrhythmia initiated at baseline study; nonpharmacological treatment would appear preferable in these patients. Further, since a relatively high arrhythmic recurrence rate has been noted in individuals with suppressible sustained ventricular tachycardia/fibrillation during drug therapy and a left ventricular ejection fraction less than 30%, we recommend serial electrophysiological/pharmacological testing primarily for patients with inducible sustained ventricular tachyarrhythmias with an ejection fraction greater than or equal to 30%.
STUDY OBJECTIVE: We determine survival for out-of-hospital cardiac arrests in Los Angeles using the Utstein method and compare these data with that reported for other urban and suburban areas. METHODS: This was a prospective observational cohort study of adult patients in Los Angeles presenting with nontraumatic, out-of-hospital cardiac arrest and with attempted out-of-hospital resuscitative efforts between July 1, 2000, and July 1, 2001. Entry criteria, time intervals, and nodal events conformed to Utstein template recommendations. The single target endpoint was neurologically intact survival at hospital discharge. RESULTS: Of 2,021 consecutive cardiac arrest patients on whom resuscitation was attempted, 1,700 (84%) met entry criteria as a primary cardiac event. Overall, neurologically intact survival was 1.4% (99% confidence interval [CI] 0.8% to 2.4%) Three patients were lost to follow-up. Survival from bystander-witnessed ventricular fibrillation was 6.1% (99% CI 3.3% to 11.0%). Absolute survival differences from witnessed ventricular fibrillation was higher but not statistically different than that from Chicago (-3%; 99% CI -8% to 2%) and New York City (-2%; 99% CI -6% to 3%). The rate of bystander cardiopulmonary resuscitation (CPR) for our population was 28%, for which the overall survival rate was 2.1%. The survival rate for patients with witnessed arrests and bystander CPR was 3.2%. Among patients with no bystander CPR, the survival rate was 1.0%. CONCLUSION: Survival from out-of-hospital cardiac arrest in Los Angeles was low but similar to that reported for New York and Chicago. This low survival rate may be due to population density, low bystander CPR rates, and traffic congestion delaying emergency response.
OBJECTIVE: To evaluate the quality of life of survivors of in-hospital and out-of-hospital cardiac arrest, and to correlate quality of life with clinically important parameters. METHODS: Cohort followed at least six months after hospital discharge. Eligible patients had survived to hospital discharge after sudden cardiac arrest in 1) EDs, wards, and intensive care units of five university hospitals and 2) all locations outside hospitals in two midsized cities. Of 126 patients discharged alive, 30 died before they could be interviewed. Of the 96 patients remaining, 86 (90% of available patients, 68% of survivors to discharge) completed the interview. Quality of life was assessed with the Health Utilities Index Mark 3, which describes health as a utility score on a scale from perfect health (equal to 1.0) to death (equal to 0.) RESULTS: Mean age (+/- SD) of interviewed survivors was 65 +/- 14 years, and 47 (55%) were male; mean time between collapse and initiation of CPR was 2.2 +/- 2.6 minutes. Mean utility was 0.72 (+/- 0.22). Utilities were significantly higher among patients who had a shorter duration of resuscitation (mean = 0.81 for those who received less than 2 minutes of CPR, 0.76 for those who received 3 to 10 minutes, and 0.65 for others, p = 0.05, r2 = 0.07). Mean utilities of survivors were worse than those of the general population (mean = 0.85 +/- 0.16, p < 0.01) and those whose activities were not limited by chronic disease (mean = 0.91 +/- 0.08, p < 0.01). CONCLUSIONS: Although overall survival was poor, most survivors had acceptable health-related quality of life. Therefore, concerns about poor quality of life are not a valid reason to abandon efforts to improve the health care system's response to victims of sudden cardiac arrest. Further research is necessary to identify effective strategies for improving both survival and quality of life after cardiac arrest.
BACKGROUND: To determine the sensitivity and specificity of the self-inflating bulb (SIB) to verify tracheal intubation in out-of-hospital cardiac arrest patients. METHODS: Sixty-five consecutive adult patients with out-of-hospital cardiac arrest were enrolled. Patients were provided chest compression and ventilation by either ba-valve-mask or the esophageal tracheal double-lumen airway by ambulance crews when they arrived at the authors' department. Immediately after intubation in the emergency department, the endotracheal tube position was tested by the SIB and end-tidal carbon dioxide (ETCO2) monitor using an infrared carbon dioxide analyzer. We observed the SIB reinflating for 10 s, and full reinflation within 4 s was defined as a positive result (tracheal intubation). RESULTS: Five esophageal intubations occurred, and the SIB correctly identified all esophageal intubations. Of the 65 tracheal intubations, the SIB correctly identified 47 tubes placed in the trachea (72.3%). Delayed but full reinflation occurred in one tracheal intubation during the 10-s observation period. Fifteen tracheal intubations had incomplete reinflation during the observation period, and two tracheal intubations did not achieve any reinflation. Thirty-nine tracheal intubations were identified by ETCO2 (60%). When the SIB test is combined with the ETCO2 detection, 59 tracheal intubations were identified with a 90.8% sensitivity. CONCLUSIONS: The authors found a high incidence of false-negative results of the SIB in out-of-hospital cardiac arrest patients. Because no single test for verifying endotracheal tube position is reliable, all available modalities should be tested and used in conjunction with proper clinical judgment to verify tracheal intubation in cases of out-of-hospital cardiac arrest.