Adverse hemodynamic effects of interrupting chest compressions for rescue breathing during cardiopulmonary resuscitation for ventricular fibrillation cardiac arrest.

BACKGROUND: Despite improving arterial oxygen saturation and pH, bystander cardiopulmonary resuscitation (CPR) with chest compressions plus rescue breathing (CC+RB) has not improved survival from ventricular fibrillation (VF) compared with chest compressions alone (CC) in numerous animal models and 2 clinical investigations. METHODS AND RESULTS: After 3 minutes of untreated VF, 14 swine (32+/-1 kg) were randomly assigned to receive CC+RB or CC for 12 minutes, followed by advanced cardiac life support. All 14 animals survived 24 hours, 13 with good neurological outcome. For the CC+RB group, the aortic relaxation pressures routinely decreased during the 2 rescue breaths. Therefore, the mean coronary perfusion pressure of the first 2 compressions in each compression cycle was lower than those of the final 2 compressions (14+/-1 versus 21+/-2 mm Hg, P<0.001). During each minute of CPR, the number of chest compressions was also lower in the CC+RB group (62+/-1 versus 92+/-1 compressions, P<0.001). Consequently, the integrated coronary perfusion pressure was lower with CC+RB during each minute of CPR (P<0.05 for the first 8 minutes). Moreover, at 2 to 5 minutes of CPR, the median left ventricular blood flow by fluorescent microsphere technique was 60 mL. 100 g(-1). min(-1) with CC+RB versus 96 mL. 100 g(-1). min(-1) with CC, P<0.05. Because the arterial oxygen saturation was higher with CC+RB, the left ventricular myocardial oxygen delivery did not differ. CONCLUSIONS: Interrupting chest compressions for rescue breathing can adversely affect hemodynamics during CPR for VF.

Defining, identifying, and measuring error in emergency medicine.

The findings of a consensus committee created to address the definition, measurement, and identification of error in emergency medicine (EM) are presented. The literature of error measurement in medicine is also reviewed and analyzed. The consensus committee recommended adopting a standard set of terms found in the medical error literature. Issues surrounding error identification are discussed. The pros and cons of mandatory reporting, voluntary reporting, and surveillance systems are addressed, as is error reporting at the clinician, hospital, and oversight group levels. Committee recommendations are made regarding the initial steps EM should take to address error. The establishment of patient safety boards at each institution is also recommended.

Advance directives.

Different types of advance directives invite varying interpretation from emergency care professionals. As informed consent of a patient is not always possible to procure in emergency situations, advance directives can provide useful guidelines for clinicians' decision-making processes regarding individual patient care. Specifically communicated instructions establish a course of aggressive or nonaggressive treatment, while general wishes leave the emergency department physician to assume an innate understanding of individual patients while undertaking an active role in decision-making for that patient's care. This article explores the relationship between advance care directives and the emergency department.

Supporting emergency medicine research: developing the infrastructure.

The long-term goals of developing research within the specialty of emergency medicine (EM) include the following: 1) to continue to improve the quality and quantity of EM research in order to ultimately improve emergency patient care; 2) to maximize the research potential of emergency health care professionals in order to develop new emergency research talent and enthusiasm; and 3) to establish the academic research credentials of the specialty of EM in order to become competitive for federal research funding, and further improve emergency patient care. This article addresses the process by which the infrastructure for EM research can be developed at academic medical centers and provides recommendations. The roles of the academic chair, research director, senior researcher, and departmental faculty are discussed.

Supporting emergency medicine research: developing the infrastructure.

The long-term goals of developing research within the specialty of emergency medicine include the following: (1) to continue to improve the quality and quantity of emergency patient care; (2) to maximize the research potential of emergency health care professionals to develop new emergency research talent and enthusiasm; and (3) to establish the academic research credentials of the specialty of emergency medicine to become competitive for federal research funding, and further improve emergency patient care. This article addresses the process by which the infrastructure for emergency medicine research can be developed at academic medical centers and provides recommendations. The roles of the academic chair, research director, senior researcher, and departmental faculty are discussed.

Postresuscitation left ventricular systolic and diastolic dysfunction. Treatment with dobutamine.

BACKGROUND: Global left ventricular dysfunction after successful resuscitation is well documented and appears to be a major contributing factor in limiting long-term survival after initial recovery from out-of-hospital sudden cardiac death. Treatment of such postresuscitation myocardial dysfunction has not been examined previously. METHODS AND RESULTS: Systolic and diastolic parameters of left ventricular function were measured in 27 swine before and after successful resuscitation from prolonged ventricular fibrillation cardiac arrest. Dobutamine infusions (10 micrograms.kg-1.min-1 in 14 animals or 5 micrograms.kg-1.min-1 in 5 animals) begun 15 minutes after resuscitation were compared with controls receiving no treatment (8 animals). The marked deterioration in systolic and diastolic left ventricular function seen in the control group after resuscitation was ameliorated in the dobutamine-treated animals. Left ventricular ejection fraction fell from a prearrest 58 +/- 3% to 25 +/- 3% at 5 hours after resuscitation in the control group but remained unchanged in the dobutamine (10 micrograms.kg-1.min-1) group (52 +/- 1% prearrest and 55 +/- 3% at 5 hours after resuscitation). Measurement of the constant of isovolumic relaxation of the left ventricle (tau) demonstrated a similar benefit of the dobutamine infusion for overcoming postresuscitation diastolic dysfunction. The tau rose in the controls from 28 +/- 1 milliseconds (ms) prearrest to 41 +/- 3 ms at 5 hours after resuscitation whereas it remained constant in the dobutamine-treated animals (31 +/- 1 ms prearrest and 31 +/- 5 ms at 5 hours after resuscitation). CONCLUSIONS: Dobutamine begun within 15 minutes of successful resuscitation can successfully overcome the global systolic and diastolic left ventricular dysfunction resulting from prolonged cardiac arrest and cardiopulmonary resuscitation.

Assisted ventilation does not improve outcome in a porcine model of single-rescuer bystander cardiopulmonary resuscitation.

BACKGROUND: Mouth-to-mouth rescue breathing is a barrier to the performance of bystander cardiopulmonary resuscitation (CPR). We evaluated the need for assisted ventilation during simulated single-rescuer bystander CPR in a swine model of prehospital cardiac arrest. METHODS AND RESULTS: Five minutes after ventricular fibrillation, swine were randomly assigned to 8 minutes of hand-bag-valve ventilation with 17% oxygen and 4% carbon dioxide plus chest compressions (CC + V), chest compressions only (CC), or no CPR (control group). Standard advanced life support was then provided. Animals successfully resuscitated received 1 hour of intensive care support and were observed for 24 hours. All 10 CC animals, 9 of the 10 CC + V animals, and 4 of the 6 control animals attained return of spontaneous circulation. Five of the 10 CC animals, 6 of the 10 CC + V animals, and none of the 6 control animals survived for 24 hours (CC versus controls, P = .058; CC + V versus controls, P < .03). All 24-hour survivors were normal or nearly normal neurologically. CONCLUSIONS: In this model of prehospital single-rescuer bystander CPR, successful initial resuscitation, 24-hour survival, and neurological outcome were similar after chest compressions only or chest compressions plus assisted ventilation. Both techniques tended to improve outcome compared with no bystander CPR.

The development and evaluation of a geriatric emergency medicine curriculum. The SAEM Geriatric Emergency Medicine Task Force.

OBJECTIVE: To summarize the processes used to develop a curriculum and model of care for the emergency medical treatment of elder patients and to assess the efficacy of the teaching material in a pilot course. METHODS: A survey of emergency medicine (EM) residency directors and geriatric fellowship directors was used to identify key topics for inclusion in the didactic material. An interdisciplinary consensus process was used to develop didactic as well as teaching material in geriatric EM. Pretests and posttests were administered to 46 participants in the initial course to assess knowledge gain. Subjective course evaluations were also done. RESULTS: Test scores significantly increased from 54% correct on the pretest to 77% correct on the posttest (p < 0.001). Significant improvement in knowledge as judged by pretest and posttest results occurred in 6 of the 7 teaching modules. Subjective evaluations demonstrated good to excellent ratings for each module as well as the overall workshop. CONCLUSIONS: The process of developing a curriculum for geriatric EM is described. The initial training of instructors was effective in improving participants' knowledge of geriatric issues in EM. Participants considered the training to be effective. The effect of the training on the emergency care of elder persons remains to be determined.

Ventricular fibrillation in a swine model of acute pediatric asphyxial cardiac arrest.

STUDY OBJECTIVE: To determine cardiac rhythms in a swine model of acute pediatric asphyxial cardiac arrest. DESIGN: Prospective electrocardiographic evaluation of 36 piglets. SETTING: University hospital laboratory. INTERVENTION: Piglets were acutely asphyxiated by endotracheal tube clamping until 10 min after loss of aortic pulsations. Resuscitative efforts were then provided. RESULTS: None of the animals had ventricular fibrillation (VF) when loss of aortic pulsations occurred (11 +/- 2 min after clamping). Fourteen of the 36 piglets exhibited VF during the asphyxial insult. VF converted to asystole in four piglets prior to resuscitation. Immediately prior to resuscitation, VF occurred in 10 piglets, asystole in 19 piglets, and bradyarrhythmias in seven piglets. CONCLUSION: VF occurs frequently in this piglet model of prolonged asphyxial cardiac arrest, consistent with recent observations in pediatric prehospital cardiac arrests. VF occurred late in the asphyxial process.

Active compression-decompression versus standard cardiopulmonary resuscitation in a porcine model: no improvement in outcome.

Active compression-decompression cardiopulmonary resuscitation (CPR) is a new innovative basic life-support technique during which the anterior chest wall is actively decompressed by a suction device. CPR techniques were studied in 36 swine to test the hypothesis that active compression-decompression CPR improves coronary perfusion pressure, myocardial blood flow during CPR, and 24-hour survival. After 30 seconds of untreated ventricular fibrillation, CPR was begun and continued for 12.5 minutes by one of the three following methods: (1) active compression-decompression CPR with a suction device modified to include a precision force transducer; (2) standard CPR performed with a force transducer device; and (3) standard manual CPR performed without a force transducer device. CPR-generated coronary perfusion pressure, myocardial blood flow, and the force of compression were measured at 3 and 10 minutes of resuscitation effort. Initial return of spontaneous circulation, 24-hour survival, and trauma scores were also evaluated. Active compression-decompression CPR produced consistently better results than did standard CPR performed with a force transducer, but not better than standard CPR performed manually without a force transducer. The use of a force-measuring device with standard CPR may compromise hemodynamic response and outcome.

Research directions in emergency medicine.

The goal of emergency medicine is to improve health while preventing and treating disease and illness in patients seeking emergency medical care. Improvements in emergency medical care and the delivery of this care can be achieved through credible and meaningful research efforts. Improved delivery of emergency medical care through research requires careful planning and the wise use of limited resources. To achieve this goal, emergency medicine must provide appropriate training of young investigators and attract support for their work. Promotion of multidisciplinary research teams will help the specialty fulfill its goals. The result will be the improvement of emergency medical care which will benefit not only the patients emergency physicians serve but also, ultimately, the nation's health.

A randomized, blinded trial of high-dose epinephrine versus standard-dose epinephrine in a swine model of pediatric asphyxial cardiac arrest.

OBJECTIVE: To determine whether high-dose epinephrine administration during cardiopulmonary resuscitation (CPR) in a swine pediatric asphyxial cardiac arrest model improves outcome (i.e., resuscitation rate, survival rate, and neurologic function) compared with standard-dose epinephrine. DESIGN: A randomized, blinded study. SETTING: A large animal cardiovascular laboratory at a university. SUBJECTS: Thirty domestic piglets (3 to 4 months of age) were randomized to receive standard-dose epinephrine (0.02 mg/kg) or high-dose epinephrine (0.2 mg/kg) during CPR after 10 mins of cardiac standstill with loss of aortic pulsation after endotracheal tube clamping. INTERVENTIONS: Two minutes of CPR were provided, followed by advanced pediatric life support. Successfully resuscitated animals were supported in an intensive care unit (ICU) setting for 2 hrs and then observed for 24 hrs. MEASUREMENTS AND MAIN RESULTS: Electrocardiogram, thoracic aortic blood pressure, and right atrial blood pressure were monitored continuously until the intensive care period ended. Survival rate and neurologic outcome were determined. Return of spontaneous circulation was obtained in 13 of 15 high-dose epinephrine piglets vs. ten of 15 standard-dose epinephrine piglets (p < .20). Four of 13 high-dose piglets died in the ICU period after initial resuscitation vs. 0 of ten standard-dose piglets (p < or = .05). Nine high-dose piglets survived 2 hrs vs. ten standard-dose piglets. Three piglets in each group survived for 24 hrs, but all were severely neurologically impaired. Two minutes after resuscitation, piglets treated with high-dose epinephrine had higher heart rates (210 +/- 24 vs. 189 +/- 40 beats/min, p < .05) and higher aortic diastolic pressures (121 +/- 39 vs. 74 +/- 40 mm Hg, p < .01). Within 10 mins of return of spontaneous circulation, severe tachycardia (> 240 beats/min) was more frequently noted in the high-dose group than in the standard-dose group (p < .05). All four high-dose piglets that died in the ICU period experienced ventricular fibrillation within 10 mins of return of spontaneous circulation. CONCLUSIONS: High-dose epinephrine did not improve 2-hr survival rate, 24-hr survival rate, or neurologic outcome. High-dose epinephrine resulted in severe tachycardia and hypertension immediately after resuscitation and in a higher mortality rate immediately after resuscitation.