Hemodynamic and catecholamine stress responses to insertion of the Combitube, laryngeal mask airway or tracheal intubation.
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OBJECTIVE: To compare the prognostic ability of sensory evoked potentials in cardiac arrest survivors with the outcome predicted by a panel of experienced emergency physicians based on detailed prehospital, clinical, and laboratory data. DESIGN: Inception cohort study. SETTING: Medical intensive care unit and department of emergency medicine at a university hospital. PATIENTS: A total of 162 unconscious, mechanically ventilated patients who survived > or =24 hrs after resuscitation from cardiac arrest. INTERVENTIONS: Recording of sensory evoked potentials and outcome prediction after review of detailed clinical and laboratory data by emergency physicians within 24 hrs after cardiac arrest. MEASUREMENTS AND MAIN RESULTS: At 6 months, the outcome of 36 patients was classified as favorable and 126 patients were rated as poor. After review of prehospital data, emergency physicians predicted favorable vs. poor outcome with a sensitivity of 70% and a specificity of 65%. After additional assessment of data 1 hr after cardiac arrest, the sensitivity of emergency physician predictions increased to 80%, whereas the specificity decreased to 48%. Outcome prediction by emergency physicians was most accurate after obtaining detailed patient data 24 hrs after cardiac arrest (sensitivity, 81%; specificity, 58%). In 35 of 36 patients with favorable outcomes, the cortical evoked potential N70 peak was detected between 72 and 128 msec. Of 113 patients with an N70 peak latency >130 msec or an absent N70 peak, all except one had a poor outcome. By using a cutoff of 130 msec, the N70 peak latency alone had a sensitivity of 94% and a specificity of 97%. The predictive accuracy of the N70 peak latency was significantly higher than the clinical assessment 24 hrs after cardiac arrest (91% vs. 76%, p = .0003). CONCLUSION: In unconscious cardiac arrest survivors, a recording of long-latency sensory evoked potentials is more accurate in predicting individual outcome than an emergency physician review of clinical data.
OBJECTIVE: To compare plasma concentrations and cardiovascular effects of epinephrine after application via a conventional endotracheal airway and via the esophageal lumen of a new emergency airway, the esophageal tracheal Combitube. DESIGN: Prospective, randomized study. SETTING: Center for Biomedical Research, University of Vienna. SUBJECTS: Fourteen juvenile swine received either an endotracheal tube (Group A) or a Combitube in esophageal position (Group B). INTERVENTIONS: In Part I of the study, epinephrine was administered during spontaneous beating of the heart; in Part II, epinephrine was administered during cardiopulmonary resuscitation, using a ten-fold higher dosage in Group B, respectively. MEASUREMENTS: Plasma epinephrine levels were measured 1, 2, 3, 5, 7, 10, 15, and 30 mins after application. Systolic arterial blood pressure and cardiac output in Part I, and end-tidal CO2 and coronary perfusion pressure in Part II were recorded. MAIN RESULTS: In Part I, increased levels of plasma epinephrine and systolic arterial pressure were maintained significantly longer in Group B when compared with Group A. In Part II, no significant differences between the groups were found with regard to plasma epinephrine levels and hemodynamic variables. CONCLUSION: Epinephrine applied via the esophageal lumen of the Combitube in a ten-fold higher dosage has similar effects on plasma epinephrine levels and hemodynamic variables compared to endotracheal administration.
The efficacy, pharmacokinetics, safety, and tolerability of E 047/1, an amiodarone derivative, were evaluated in patients with acute supraventricular or ventricular arrhythmia. In an open, nonrandomized prospective multicenter trial, 20 patients were treated with three different i.v. dosage regimens of E 047/1. Arrhythmia termination indicated efficacy. Pharmacokinetics were determined by measurements of drug plasma levels. Safety was judged by changes of blood pressure, heart rate, ECG parameters, and appearance of adverse events. For local tolerability, effects at the site of infusion were assessed. In patients with atrial fibrillation and/or atrial flutter, drug plasma levels and prolongation of QT interval were correlated with efficacy. In 10 (50%) patients, therapeutic intervention with E 047/1 was successful. Drug plasma levels rapidly decreased within 1 h after administration. Blood pressure values and ECG parameters stayed constant during the observation period. Proarrhythmic effects were not observed. As adverse events, vertigo, vomiting, and nausea in three (15%) and hypotension in one (5%) patient, respectively, occurred in the high-dose bolus regimen only. At the site of infusion, no adverse effects were found. No dependency between drug plasma levels and arrhythmia termination was found. E 047/1 has proven to be efficient and safe in the treatment of arrhythmia. E 047/1 is characterized by rapid plasma elimination, absence of proarrhythmic or cardiodepressive effects, mild adverse events, and excellent local tolerability. For further investigation, we recommend a combined bolus- and weight-adapted infusion regimen.
BACKGROUND AND PURPOSE: Recent animal studies showed that mild resuscitative hypothermia improves neurological outcome when applied after cardiac arrest. In a 3-year randomized, prospective, multicenter clinical trial, we hypothesized that mild resuscitative cerebral hypothermia (32 degrees C to 34 degrees C core temperature) would improve neurological outcome after cardiac arrest. METHODS: We lowered patients' temperature after admission to the emergency department and continued cooling for at least 24 hours after arrest in conjunction with advanced cardiac life support. The cooling technique chosen was external head and total body cooling with a cooling device in conjunction with a blanket and a mattress. Infrared tympanic thermometry was monitored before a central pulmonary artery thermistor probe was inserted. RESULTS: In 27 patients (age 58 [interquartile range [IQR] 52 to 64] years; 7 women; estimated "no-flow" duration 6 [IQR 1 to 11] minutes and "low-flow" duration 15 [IQR 9 to 23] minutes; admitted to the emergency department 36 [IQR 24 to 43] minutes after return of spontaneous circulation), we could initiate cooling within 62 (IQR 41 to 75) minutes and achieve a pulmonary artery temperature of 33+/-1 degrees C 287 (IQR 42 to 401) minutes after cardiac arrest. During 24 hours of mild resuscitative hypothermia, no major complications occurred. Passive rewarming >35 degrees C was accomplished within 7 hours. CONCLUSIONS: Mild resuscitative hypothermia in patients is feasible and safe. A clinical multicenter trial might prove that mild hypothermia is a useful method of cerebral resuscitation after global ischemic states.
BACKGROUND AND PURPOSE: The apolipoprotein E 3/3 (apoE 3/3) genotype is associated with a reduced risk of developing Alzheimer's disease and with a favorable neurological outcome after traumatic head injury. In vitro studies suggest that the most common genotype, apoE 3/3, may be involved in neuroprotective and neuroregenerative mechanisms. The aim of this study was to determine whether the apoE 3/3 genotype has an impact on survival and neurological outcome after cardiopulmonary resuscitation. METHODS: Eighty patients with cardiac arrest were investigated prospectively for their apoE genotype. Epidemiological data were assessed according to recommended guidelines. Patients were divided into 2 groups, ie, with the apoE 3/3 genotype present or absent, and tested for differences in survival and neurological outcome. Further statistical analysis with respect to survival and neurological outcome was performed by using a stepwise logistic regression analysis. RESULTS: Patients with the apoE 3/3 genotype had a significantly higher survival rate (64% versus 33%, P:=0.007) and more often a favorable neurological outcome (55% versus 27%, P:=0. 013) compared with patients with other apoE genotypes. The apoE 3/3 genotype was shown to be a substantial predictive factor for a favorable neurological outcome (odds ratio 3.2) and was, apart from other essential factors, predictive for survival (odds ratio 4.4) after cardiopulmonary resuscitation. CONCLUSIONS: These data give evidence that patients with the apoE 3/3 genotype have a better chance of recovery after cardiopulmonary resuscitation than do patients with apoE genotypes other than 3/3.
OBJECTIVE: To describe our experience with the use of percutaneous cardiopulmonary bypass as a therapy for cardiac arrest in an adult patient intoxicated with verapamil. DESIGN: Case report. SETTING: Emergency department of a university hospital. PATIENT: A patient with cardiac arrest after severe verapamil intoxication. INTERVENTIONS: Percutaneous cardiopulmonary bypass and theophylline therapy. CASE REPORT: A 41-yr-old white male had taken 4800-6400 mg of verapamil in a suicide attempt. On arrival of the ambulance physician, the patient was conscious with weak palpable pulses and was transported to a nearby hospital. The patient developed a pulseless electrical activity, and cardiopulmonary resuscitation was started. Despite all advanced life support efforts, the patient remained in cardiac arrest. Therefore, he was transferred under ongoing cardiopulmonary resuscitation to our department, where percutaneous cardiopulmonary bypass was initiated immediately (2.5 hrs after cardiac arrest). The first verapamil serum concentration obtained at admittance to our institution was 630 ng/mL. After several ineffective intravenous epinephrine applications, the administration of 0.48 g of theophylline as an intravenous bolus 6 hrs and 18 mins after cardiac arrest led to the return of spontaneous circulation. The patient remained stable and was transferred to an intensive care unit the same day. He woke up on the 12th day and was extubated on the 18th day. After transfer to a neuropsychiatric rehabilitation hospital, he recovered totally. CONCLUSION: In patients with cardiac arrest attributable to massive verapamil overdose, percutaneous extracorporeal cardiopulmonary bypass can provide adequate tissue perfusion and sufficient cerebral oxygen supply until the drug level is reduced and restoration of spontaneous circulation can be achieved.
BACKGROUND AND PURPOSE: The prediction of neurological outcome in comatose cardiac arrest survivors has enormous ethical and socioeconomic implications. The purpose of the present study was to investigate the prognostic relevance of the time course of serum neuron-specific enolase (NSE) as a biochemical marker of hypoxic brain damage. METHODS: Serial analysis of serum NSE levels was performed in 56 patients resuscitated from witnessed, nontraumatic, normothermic, in- or out-of-hospital cardiac arrest. The neurological outcome was evaluated with the use of the cerebral performance category (CPC) within 6 months after restoration of spontaneous circulation (ROSC). The Mann-Whitney U test was used to compare patients with good (CPC 1 to 2) and bad (CPC 3 to 4) neurological outcome. The diagnostic performance at different time points after ROSC was described in terms of areas under receiver operating characteristic curves according to standard methods. RESULTS: Patients with a bad neurological outcome (CPC 3 to 4) had significantly higher NSE levels than those with a good neurological outcome at 12 (P=0.004), 24 (P=0.04), 48 (P<0.001), and 72 hours (P<0.001) after ROSC. The maximum NSE level measured within 72 hours after ROSC was also significantly higher in patients with a bad neurological outcome (P<0.001). The NSE value at 72 hours after ROSC was the best predictor of neurological outcome (area under the curve=0.92+/-0.04). In addition, we also found a significant difference in the time course of NSE concentrations during the first 3 days after ROSC. CONCLUSIONS: Serum NSE levels are valuable adjunctive parameters for assessing neurological outcome after cardiac arrest.
Opioids are well known to cause cardiovascular depression. The aim of the present investigation was to determine whether an interaction of opioid derivatives with catecholamines might be involved in these hemodynamic alterations. Six comatose patients were enrolled into a prospective, nonrandomized pilot trial. All patients first received a continuous i.v. infusion of dobutamine (10 microgram. kg-1. min-1) paralleled by continuous administration of midazolam (0.4 mg. kg-1. h-1); thereafter, fentanyl was added i.v. (4 microgram. kg-1. h-1). Hemodynamic parameters as well as dobutamine and endogenous catecholamines plasma levels were determined. The mean arterial blood pressure did not change significantly during the whole study period. The continuous administration of dobutamine (steady-state plasma concentrations: 217 +/- 118 ng. ml-1) increased the beta1-adrenergic receptor-mediated hemodynamic parameters such as heart rate, stroke volume index, cardiac index, and oxygen delivery index (p <.05). The concomitant administration of fentanyl decreased the heart rate-dependent hemodynamic parameters (p <.05), suggesting that fentanyl antagonizes the chronotropic effects of dobutamine. In parallel, dobutamine plasma levels increased significantly (275 +/- 165 ng. ml-1; p <.05). Noteworthy, after administration of fentanyl, oxygen delivery and consumption index returned to baseline values. Radioligand binding experiments on rat cardiac ventricular microsomes ruled out a direct interaction of fentanyl with beta-adrenergic receptors and, more importantly, a fentanyl-induced inhibition of beta-adrenergic receptor G protein coupling. Our observations suggest that fentanyl inhibits the frequency-related hemodynamic changes induced by dobutamine. The underlying mechanism is independent of beta-adrenergic receptors, but is powerful enough to abolish the salutary effect of dobutamine on oxygen delivery and consumption.
A questionnaire was sent to 97 Austrian intensive care units to define the current practises of predicting neurologic outcome in patients with anoxic encephalopathy after cardio-pulmonary resuscitation. All relevant prognostic predictors, such as clinical scales, electrophysiological techniques and laboratory tests were included to examine if these procedures influence the decision to withdraw life support. The answers of 68 (70%) units were collected and analysed. The results show that tests such as somatosensory evoked potential of the determination of brain cell-specific cytosolic enzymes are without any practical importance in Austria. In addition, the methods of reducing life support were evaluated. According to the controversial discussion in the literature, there is no common approach to this problem, especially in the question of withdrawing controlled mechanical ventilation. The result of our survey show, that there is a need for general guidelines to determine the prognosis and the methods of withdrawing life support which could be used in all intensive care units regardless of their size and technical infrastructure.
BACKGROUND: Epinephrine is the drug of choice in advanced cardiac life support, but it can have deleterious side effects after restoration of spontaneous circulation. OBJECTIVE: To investigate the association between the cumulative epinephrine dose used in advanced cardiac life support and neurologic outcome after cardiac arrest. DESIGN: Retrospective cohort study. SETTING: University hospital. PATIENTS: Adults admitted to the emergency department with witnessed, nontraumatic, normothermic ventricular fibrillation cardiac arrest and unsuccessful initial defibrillation. MEASUREMENTS: Functional neurologic outcome was regularly assessed by cerebral performance category (CPC) within 6 months after cardiac arrest. A CPC of 1 or 2 was defined as favorable recovery. RESULTS: Among 178 enrolled patients, the median cumulative epinephrine dose administered was 4 mg (range, 0 to 50 mg). In 151 patients (84%), spontaneous circulation was restored; 63 of these 151 patients (42%) had favorable neurologic recovery. Patients with an unfavorable CPC received a significantly higher cumulative dose of epinephrine than did patients with a favorable CPC (4 mg compared with 1 mg; P < 0.001). This finding persisted after stratification by duration of resuscitation. After possible cofounders were controlled for, the cumulative epinephrine dose remained an independent predictor of unfavorable neurologic outcome. CONCLUSIONS: The results indicate that an increasing cumulative dose of epinephrine administered during resuscitation is independently associated with unfavorable neurologic outcome after ventricular fibrillation cardiac arrest.
BACKGROUND: International guidelines recommend differentiation between cardiac and noncardiac causes of cardiac arrest. The aim of this study was to find the rate of agreement between primarily postulated and definitive causes of cardiac arrest. METHODS AND RESULTS: We retrospectively analyzed the primarily presumed cause of cardiac arrest as determined by the emergency room physician on admission in all patients admitted to the emergency department of one urban tertiary care hospital. This was compared with the definitive cause as established by clinical evidence or autopsy. Within 4 years, the initially presumed cause was unclear in 24 (4%) of 593 patients. In the remaining 569 patients, the presumed cause was correct in 509 (89%) and wrong in 60 (11%) cases. Cardiac origin was presumed in 421 (71%) and the definitive cause in 408 (69%) cases. Noncardiac origin was presumed in 148 (25%) and the definitive cause in 185 (31%) patients. Presumed cardiac cause was sensitive (96%) but less specific (77%). Noncardiac causes such as pulmonary embolism, cerebral disorders, or exsanguination were those most frequently overlooked. Asystole occurred significantly more often in patients in whom presumed cause remained undetermined or differed from the definitive cause. CONCLUSIONS: Cause of cardiac arrest is not as easily recognized as anticipated, especially when the initial rhythm is different from ventricular fibrillation. This might affect comparability of study results, therapeutic strategies, prognosis, and outcome. Patients in whom the presumed cause was confirmed as being correct had significantly better survival and neurological outcome.
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.
A 79-year 65 kg male called the ambulance service 4 h after ingestion of 100 tablets of digoxin 0.1 mg complaining of nausea and vomiting. The ECG showed an idioventricular escape rhythm with a heart rate of 30/min. After 0.5 mg atropine, heart rate increased to 80/min. Soon after admission to the emergency department, the patient developed electromechanical dissociation. Due to persistent cardiac arrest, percutaneous cardiopulmonary bypass was started, and the ECG rhythm changed to ventricular fibrillation. Several attempts to terminate ventricular fibrillation by electrical defibrillation failed. Fifty-eight minutes after cardiac arrest, antidigoxin-Fab was administered and 1 h 25 min after cardiac arrest, ventricular fibrillation was terminated by the tenth electrical defibrillation attempt. Initially, the patient's overall status improved over the next 2 days, but then he developed a severe adult respiratory distress syndrome and died of unresponsive septic shock 12 days after ingestion of digoxin. This case demonstrates that percutaneous cardiopulmonary bypass may provide support in patients with cardiac arrest due to massive digoxin overdose. This temporary support can maintain adequate tissue perfusion during the time required for drug neutralization in order to achieve successful defibrillation. Percutaneous cardiopulmonary bypass should be considered in patients with severe, but temporary cardiac dysfunction due to a life-threatening drug overdose.
The purpose of this study was to describe the life of survivors after successful resuscitation and to see if there was an association with the type of emergency cardiac care. The 'Utstein-style' data of patients surviving non-traumatic cardiac arrest 24 (14-32) months were prospectively collected. The everyday activities and psychological concerns of patients with a cerebral performance category (CPC) of 1 and 2 using a questionnaire were analyzed. The chi2-square test was used for statistical analysis. The questionnaires of 92 patients (median age 59, IQR 51-68; females 36) were evaluated. Patients enjoy life (84%; n=73), have depression (36%; n=31), consider their survival a 'second chance' (84%; n=73) and fear that they may suffer cardiac arrest again (56%; n = 45). The average quality of life is 7 on a scale from 0 (worst) to 10 (perfect). The majority of cardiac arrest survivors have a satisfactory life. No significant correlation between the type of emergency cardiac care and post cardiac arrest life was found. The fact that there was no association with the type of emergency cardiac care may be due to the narrow selection of patients (CPC 1 and 2), the small number of patients or factors contributing to post cardiac arrest life other than emergency treatment.
OBJECTIVES: This study sought to determine the influence of resuscitative procedures, such as chest compressions and external defibrillation, on the release of creatine kinase (CK)-MB and cardiac troponin T (cTnT). METHODS: In 87 patients with out-of-hospital cardiac arrest and successful cardiopulmonary resuscitation (CPR), the initial ECG rhythm, the duration of cardiac arrest and CPR, and the number of defibrillations were assessed on arrival in the hospital. The serum CK-MB and cTnT were measured 12 h after the event. We also assessed whether the patient developed cardiogenic shock within 12 h, and if the patient had acute myocardial infarction (AMI), which was confirmed or eliminated by of typical ECG findings, thallium-201 myocardial scintigraphy, or autopsy within the hospital stay. A backward stepwise linear regression model was applied to assess the association between the markers of myocardial injury (CK-MB and cTnT) and the above clinical variables. RESULTS: CK-MB concentrations were independently associated with the presence of AMI [B 68.5 (SE 28.5, P = 0.018)], the duration of CPR (as a measure of trauma to the chest by means of chest compressions) [B 2.07 (SE 1.01, P = 0.045)] and cardiogenic shock [B 52.3 (SE 23.4, P = 0.03)]. The remaining clinical variables listed were excluded by the model. Cardiac troponin T concentrations were only associated with the presence of AMI [B 4.86 (SE 1.34, P = 0.0005)]. There was a non-significant association between increasing serum cTnT concentrations and the presence of cardiogenic shock [B 2.51 (SE 1.46, P = 0.09)]. The remaining clinical variables were excluded by the model. CONCLUSION: The release of CK-MB appears to be influenced by the duration of resuscitation and the presence of cardiogenic shock. This has to be considered when interpreting serum CK-MB concentrations after CPR. The release of cTnT seems to be only associated with acute myocardial infarction, but not with the duration of chest compressions, or with the number of defibrillations administered.
OBJECTIVE: To assess the association between arterial lactate concentration on admission and the duration of human ventricular fibrillation cardiac arrest, and to what degree the arterial lactate concentration on admission is an early predictor of functional neurological recovery in human cardiac arrest survivors. DESIGN: Cohort study. Arterial lactate concentrations and out-of-hospital data concerning cardiac arrest and cardiopulmonary resuscitation were collected retrospectively according to a standardized protocol. Functional neurological recovery was assessed prospectively at regular intervals for 6 months. SETTING: Emergency department of an urban tertiary care hospital. PATIENTS: A total of 167 primary survivors of witnessed out-of-hospital ventricular fibrillation cardiac arrest. MEASUREMENTS: The association between arterial lactate concentration on admission, the duration of cardiac arrest, and functional neurological recovery was assessed. Further, we assessed whether admission concentrations of arterial lactate and duration of cardiac arrest can predict unfavorable functional neurological recovery. Functional neurological recovery was measured in cerebral performance categories (CPC). No or minimal functional impairment (CPC 1 and 2) was defined as favorable outcome; the remaining categories (CPC 3, 4 and 5) were defined as unfavorable functional neurological recovery. RESULTS: In 167 patients, a weak association between total duration of cardiac arrest and admission levels of lactate (r = 0.49, P < 0.001) could be shown. With increasing admission concentrations of arterial lactate functional neurological recovery was more likely to be unfavorable (OR 1.15 per mmol/l increase, 95% CI 1.04-1.27). Nevertheless, only at very high levels of lactate (16.3 mmol/l) could unfavorable neurological recovery be detected with 100% specificity, yielding a very low sensitivity of 16%. CONCLUSIONS: The arterial admission lactate concentration after out-of-hospital ventricular fibrillation cardiac arrest is a weak measure of the duration of ischemia. High admission lactate levels are associated with severe neurological impairment. However, this parameter has poor prognostic value for individual estimation of the severity of subsequent functional neurological impairment.
The aim of the study was to compare the effect of a 30 and 50% duty cycle on coronary perfusion pressure (CPP) and end tidal carbon dioxide (ETCO2) and to determine whether a duty cycle of 30% can be achieved manually. After 3 min of ventricular fibrillation cardiac arrest, pigs were resuscitated in two groups with changing duty cycles every 3 min: group A starting with 50 and then 30%; and group B starting with 30 and then 50%. After administration of epinephrine, duty cycles in group A were 50 and then 30%, in group B initially 30% and then 50% Before administration of epinephrine, no significant differences in CPP between the 30 and 50% duty cycles were found; after epinephrine CPP increased with both duty cycles. ETCO2 did not vary before epinephrine; after epinephrine, there were statistically significant differences but there is doubt regarding the clinical relevance of these differences. Survival was 4/6 in group A and 3/5 in group B (NS). It is possible to perform a manual duty cycle of 30%. However, our data do not support the use of a 30% duty cycle during cardiopulmonary resuscitation (CPR).