Eric A. Davis

Use of Automated External Defibrillators by Police Officers for Treatment of Out-of-Hospital Cardiac Arrest

OBJECTIVE To determine the feasibility of police officers providing defibrillation with automated external defibrillators (AEDs) and to assess the effectiveness of this strategy in reducing time to defibrillation of victims of out-of-hospital sudden cardiac arrest. METHODS This was a prospective, interventional cohort study with historical controls conducted in 7 suburban communities in which police usually arrived at the scene of medical emergencies before EMS personnel. All adult patients who suffered cardiac arrest before EMS arrival and on whom EMS personnel attempted resuscitation were enrolled. Police officers who were trained to use and equipped with AEDs during the intervention phase were dispatched simultaneously with EMS to medical emergencies. Police were instructed to use the AED immediately on determination of pulselessness. Outcome measures were the difference between control and intervention phases in interval from the time the call was received at dispatch to the time of first defibrillation and in rate of survival to hospital discharge for patients initially in ventricular fibrillation. RESULTS EMS personnel attempted 183 resuscitations in the control phase and 283 during the intervention; of these, 80 (44%) and 127 (45%), respectively, involved patients with initial ventricular fibrillation rhythms. Mean time to defibrillation decreased from 11.8+/-4.7 minutes in the control phase to 8.7+/-3.7 minutes in the intervention phase (P<.0001). Survival to hospital discharge of patients in ventricular fibrillation did not differ between phases (6% control versus 14% intervention, P=.1). When police arrived before EMS personnel, shock administered by police compared with shock administered by EMS was associated with improved survival (26% [12/46] versus 3% [1/29], P=.01). Logistic regression analysis revealed AED use was an independent predictor of survival to hospital discharge. CONCLUSION In 7 suburban communities, police use of AEDs decreased time to defibrillation and was an independent predictor of survival to hospital discharge.

The effects of graded doses of epinephrine on regional myocardial blood flow during cardiopulmonary resuscitation in swine

Although epinephrine has been shown to improve myocardial blood flow during cardiopulmonary resuscitation (CPR), the effects of standard as well as larger doses of epinephrine on regional myocardial blood flow have not been examined. In this study we compared the effects of various doses of epinephrine on regional myocardial blood flow after a 10 min arrest in a swine preparation. Fifteen swine weighing greater than 15 kg each were instrumented for regional myocardial blood flow measurements with tracer microspheres. Regional blood flow was measured during normal sinus rhythm. After 10 min of ventricular fibrillation, CPR was begun and regional myocardial blood flow was determined. Animals were then randomly assigned to receive 0.02, 0.2, or 2.0 mg/kg epinephrine by peripheral injection. One minute after drug administration, regional myocardial blood flow measurements were repeated. The adjusted regional myocardial blood flows (ml/min/100 g) for animals given 0.02, 0.2, and 2.0 mg/kg epinephrine, respectively, were as follows: left atrium, 0.9, 67.4, and 58.8; right atrium, 0.3, 46.2, and 38.5; right ventricle, 0.7, 82.3, and 66.9; right interventricular septum, 1.7, 125.5, and 99.1; left interventricular septum, 2.8, 182.8, 109.5; mesointerventricular septum, 16.8, 142.2, and 79.2; left ventricular epicardium, 19.2, 98.5 and 108.7; left ventricular mesocardium, 22.8, 135.0, and 115.8; and left ventricular endocardium, 2.5, 176.1, and 132.9). All comparisons between the groups receiving 0.02 and 0.2 mg/kg epinephrine were statistically significant (p less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative effect of graded doses of epinephrine on regional brain blood flow during CPR in a swine model

Cerebral blood flow (CBF) with conventional closed-chest cardiopulmonary resuscitation (CCPR) has been measured at only 2% to 11% of prearrest values. The purpose of our study was to determine whether the peripheral administration of higher doses of epinephrine than currently recommended during CCPR following a prolonged cardiac arrest improves CBF compared to CCPR using a standard dose of epinephrine. Fifteen swine were randomized to receive CCPR plus 0.02 mg/kg, 0.2 mg/kg, or 2.0 mg/kg epinephrine through a peripheral IV line following a ten-minute cardiopulmonary arrest and three minutes of CCPR. Regional CBF measurements were made by radionuclide microsphere technique during normal sinus rhythm (NSR), CCPR, and following epinephrine administration. The adjusted regional blood flows (in mL/min/100 g) following epinephrine administration for the 0.02-, 0.2-, and 2.0-mg/kg groups were, respectively, left cerebral cortex (3.3, 13.1, 11.8); right cerebral cortex (3.9, 13.8, 12.2); cerebellum (9.2, 32.0, 33.1); midbrain/pons (9.9, 32.1, 32.3); medulla (10.6, 61.5, 54.2); and cervical spinal cord (12.2, 53.8, 35.8). In this swine model, 0.2 mg/kg and 2.0 mg/kg epinephrine significantly increased regional CBF over that seen with standard doses. Because neuronal survival is dependent on flow rates of 10 to 15 mL/min/100 g, this preliminary evidence suggests that these higher doses of epinephrine may help improve neurological outcome in CCPR.

Emergency department sonography by emergency physicians

A retrospective study was conducted to examine whether emergency physicians can perform accurate ultrasonography that influences the diagnosis and treatment of selected disorders in the emergency department (ED). The physicians acquired a moderate level of expertise in sonography using a series of practical demonstrations and lectures. Patients with symptoms suggestive of cardiac, gynecologic, biliary tract, and abdominal vascular disease periodically underwent ED sonography. The initial interpretation was used as a diagnostic adjunct to subsequent therapy. The accuracy of positive sonographic findings was assessed by confirmatory testing, formal review, or confirmatory clinical course. Emergency physicians were able to diagnose correctly (1) the presence and approximate size of pericardial effusions, (2) the presence or absence of organized cardiac activity in patient with clinical electrical mechanical dissociation, (3) the presence or absence of intrauterine pregnancy in pregnant patients with lower abdominal/pelvic complaints, (4) the position of intrauterine devices in patients with suspected uterine perforation, (5) the presence of gallstones in patients with suspected biliary tract disease, and (6) the presence and size of abdominal aortic aneurysms in patients with pulsatile masses or unexplained abdominal pain. It was concluded that reliable sonography which influences diagnosis and therapy can be performed by emergency physicians and that sonography should become a standard procedure in EDs.

The effect of epinephrine versus methoxamine on regional myocardial blood flow and defibrillation rates following a prolonged cardiorespiratory arrest in a swine model

Recent studies in swine have shown that larger doses of epinephrine than those currently employed for cardiopulmonary resuscitation (CPR) significantly improve regional myocardial blood flow following prolonged cardiac arrest. The dose-response effect of a pure alpha-adrenergic agonist, methoxamine, on regional myocardial blood flow has not been investigated in this setting. This study compared the effect of high-dose epinephrine with graded doses of methoxamine on regional myocardial blood flow, oxygen delivery/utilization, and defibrillation rates during CPR. Twenty swine were instrumented for regional myocardial blood flow measurements using radiolabeled tracer microspheres. Measurements of regional myocardial blood flow, oxygen delivery, and oxygen consumption were made during normal sinus rhythm. Ventricular fibrillation was then induced. Following 10 minutes of ventricular fibrillation, CPR was initiated with a pneumatic compressor. Regional myocardial blood flow, oxygen delivery, and oxygen consumption were then measured during CPR. Following 3 minutes of CPR, the swine were allocated to one of four treatment groups (five per group): group I, epinephrine 0.2 mg/kg; group II, methoxamine 0.1 mg/kg; group III, methoxamine 1.0 mg/kg; and group IV, methoxamine 10.0 mg/kg. One minute after drug administration, regional myocardial blood flow, oxygen delivery, and oxygen consumption measurements again were made. Three and one half minutes after drug administration, defibrillation was attempted. Regional myocardial blood flow following drug administration was compared using an analysis of covariance. Epinephrine (0.2 mg/kg) significantly improved myocardial blood flow (P less than .002) for all tissues examined compared with all doses of methoxamine.(ABSTRACT TRUNCATED AT 250 WORDS)

Performance of police first responders in utilizing automated external defibrillation on victims of sudden cardiac arrest.

OBJECTIVE Rates of resuscitation from cardiac arrest are directly tied to time to defibrillation. To maximize results, the first arriving care provider should be equipped and trained to defibrillate. This would include police in those systems where they serve this function; to date, no training program has been examined for effectiveness in this group. The purpose of this study was to evaluate a training program designed to train police first responders in the use of an automated external defibrillator (AED). METHODS One hundred seventy police officers previously trained to the level of first responders underwent a four-hour course to teach incorporation of the AED in their practice. The evaluation of police performance was assessed by written tests prior to, immediately after, and six months post initial training. Actual field use was evaluated by using separate data collection forms filled out at the time of the resuscitation by both police and EMS providers. Each trip sheet was also reviewed. Cassette tapes from the AED were reviewed for continuous ECG tracings and audio recordings to validate and confirm the previous data. RESULTS One hundred twenty-eight police cases were reviewed. The officers performed with few errors in AED operation, with the only problem areas being incorrect airway management and delay in performance of CPR to use the AED to reanalyze a nonshockable rhythm. These results were compared with those of the only two other studies examining the performance of first responders, which were EMTs and firefighters. The police results compared favorably with, and in some instances exceeded, those results. CONCLUSION Police first responders trained in the use of AEDs performed at a level equivalent or superior to that in other reported studies. Future training strategies should stress proper integration of airway and CPR skills.

Methoxamine versus epinephrine on regional cerebral blood flow during cardiopulmonary resuscitation.

The improvement in cerebral blood flow (CBF) during CPR after epinephrine administration has been attributed to epinephrines alpha-adrenergic properties. Methoxamine, a pure alpha-1 agonist, has only been shown to be comparable to epinephrine in restoring circulation after cardiac arrest in a canine model. This study compares the effectiveness of equipotent doses of epinephrine and methoxamine in improving CBF during CPR after a prolonged cardiac arrest in a swine model.Twenty-five swine, weighing 15.9 to 28.2 kg, underwent instrumentation for regional CBF using tracer microspheres. CBF was determined during normal sinus rhythm. After 10 min of ventricular fibrillation, CPR was begun with a pneumatic compressor. CBF measurements were again made during CPR. After 3 min of CPR, the swine were randomized to receive 0.02 or 0.2 mg/kg epinephrine, 0.1,1.0, or 10.0 mg/kg methoxamine. Five swine were allocated to each group. CBF measurements were determined after drug administration and compared using a Bonferroni multiple comparison procedure. A p-value less than .05 was considered statistically significant.This study demonstrated that, after a 10-min cardiac arrest, CBF was extremely low, averaging less than 7 ml/min 100 g during external CPR. There were no clinically significant improvements in regional CBF after 0.02 mg/kg of epinephrine, or the two lowest doses of methoxamine. The addition of 10 mg/kg of methoxamine clinically improved blood flow only to the most caudal CNS structures, including the pons, medulla, and cervical spinal cord. On the other hand, with 0.2 mg/kg of epinephrine, regional CBF averaged approximately 12 to 13 ml/min-100 g to the cerebral cortex, and surpassed 29 ml/min 100 g to more caudal CNS structures. All blood flow comparisons between the epinephrine and methoxamine-treated animals were statistically significant (p = .0001). This study suggests that epinephrine in larger doses than currently recommended significantly improves regional CBF compared to equipotent doses of methoxamine during CPR.

The Effect of High.Dose Phenylephrine Versus Epinephrine on Regional Cerebral Blood Flow During CPR

Prior studies have not found the alpha agonist phenylephrine, in a dose of 0.1 mg/kg, to be as effective as 0.20 mg/kg of epinephrine in improving regional cerebral blood flow (CBF) during CPR in swine. We undertook this study to assess whether higher doses of phenylephrine might improve regional CBF. Fifteen swine were allocated to receive either epinephrine 0.2 mg/kg, phenylephrine 1.0 mg/kg, or phenylephrine 10 mg/kg. Regional CBF measurements were made during normal sinus rhythm, during CPR, and during CPR following drug administration. Epinephrine 0.2 mg/kg was significantly better in improving regional CBF to the left and right cerebral cortices, cerebellum, midbrain, and cervical cord than was phenylephrine 1.0 mg/kg. There was no significant difference in regional CBF between the animals receiving epinephrine 0.2 mg/kg and phenylephrine 10 mg/kg. The study shows that large doses of epinephrine and phenylephrine may be required during CPR to improve regional cerebral blood flow following a prolonged arrest.

An experimental algorithm versus standard advanced cardiac life support in a swine model of out-of-hospital cardiac arrest

STUDY OBJECTIVE To compare an experimental algorithm with standard advanced cardiac life support in a swine model of out-of-hospital cardiac arrest. DESIGN Randomized, controlled experimental trial. SETTING/TYPE OF PARTICIPANT: Animal laboratory using swine. INTERVENTIONS Eighteen swine (17.8 to 23.7 kg) were sedated, intubated, anesthetized, and instrumented for monitoring of arterial and central venous pressures and ECG. Ventricular fibrillation was induced using a bipolar pacing catheter. Animals were randomized to treatment with the experimental algorithm or standard advanced cardiac life support therapy after eight minutes of untreated ventricular fibrillation. The experimental algorithm consisted of starting CPR; giving high-dose epinephrine (0.20 mg/kg), lidocaine (1.0 mg/kg), bretylium (5.0 mg/kg), and propranolol (0.5 to 1.0 mg) by peripheral IV; hyperventilating (20 to 25 breaths per minute); and delaying countershock (5 J/kg) 60 seconds after completion of drug delivery. Data were analyzed with the Students t-test and Fishers exact test. MEASUREMENTS AND MAIN RESULTS Outcome variables were arterial and central venous pressures, return of spontaneous circulation, and one-hour survival. Hemodynamics were not different between groups during CPR. Return of spontaneous circulation occurred in seven of nine swine (77%) in the experimental algorithm group versus two of nine swine (22%) in the advanced cardiac life support group (P = .057). Four of nine swine (44%) in the experimental algorithm group survived to one hour versus none of the animals in the advanced cardiac life support group (P = .041). CONCLUSION In this swine model of out-of-hospital cardiac arrest, animals treated with an experimental algorithm had a significant improvement in one-hour survival compared with those treated with advanced cardiac life support.

The comparative effects of epinephrine versus phenylephrine on regional cerebral blood flow during carciopulmonary resuscitation

Epinephrine in larger doses than currently recommended during cardiopulmonary resuscitation (CPR) has been shown to improve cerebral blood flow (CBF) following a 10-min arrest in a swine model. The purpose of this pilot study was to measure CBF during CPR, comparing high-dose epinephrine to a pure alpha-1 agonist, phenylephrine. Ten swine each weighing greater than 15 kg, were instrumented for regional CBF measurements using tracer microspheres. CBF was measured during normal sinus rhythm (NSR). Following 10 min of ventricular fibrillation, CPR was begun and regional CBF was again measured. Following 3 min of CPR, the swine were randomized to receive either epinephrine (0.2 mg/kg), or phenylephrine (0.1 mg/kg), through a peripheral intravenous line. Regional CBF was again measured 1 min after drug administration. Regional CBF following drug administration was compared using an analysis of covariance. Adjusted CBFs are expressed in ml/min per 100 g for epinephrine and phenylephrine, respectively: left cerebral cortex (12.5 vs. 2.3, P = 0.002); right cerebral cortex (13.0 vs. 2.8, P = 0.003); cerebellum (32.9 vs. 4.1, P = 0.004); midbrain (35.7 vs. 2.6, P = 0.0004), pons (30.3 vs. 2.9, P = O.006); medulla (49.5 vs. 13.6, P = 0.02) and cervical spinal cord (49.6 vs. 14.1, P = 0.003).