Does an individualized feedback mechanism improve quality of out-of-hospital CPR?

BACKGROUND: Despite its prevalence, survival from out-of-hospital cardiac arrest remains low. High quality CPR has been associated with improved survival in cardiac arrest patients. In early 2014, a program was initiated to provide feedback on CPR quality to prehospital providers after every treated cardiac arrest. OBJECTIVE: To assess whether individualized CPR feedback was associated with improved CPR quality measures in the prehospital setting. METHODS: This before and after retrospective review included all treated adult out-of-hospital cardiac arrest in patients in an urban community. Data was compared prior to and after the initiation of the CPR feedback program. We compared the percent of encounters reaching the system defined benchmarks as well as the average values for compression fraction, compression rate, compression depth, and pre-shock pause in the before period compared to the after period. RESULTS: There were 159 encounters in the before period and 117 in the after. Compared to the before group, the after group had higher average compression rates (111.2/min vs 113.8/min; p=0.042), increased compression depths (4.9cm vs 5.6cm; p<0.001), and increased rates of benchmark achievement for compression depth greater than 5cm (48.1% vs 72.6%; p<0.001). No significant difference was noted in pre-shock pause (21.4s vs 14.7s; p=0.068). Additionally, no difference was noted between groups for compression fraction, though goal achievement was high in both groups. CONCLUSION: We found that individual CPR feedback is associated with marginally improved quality of CPR in the prehospital setting. Further investigation with larger samples is warranted to better quantify this effect.

Comparison of elderly and younger patients with out-of-hospital chest pain. Clinical characteristics, acute myocardial infarction, therapy, and outcomes.

BACKGROUND: Acute myocardial infarction is associated with significantly higher mortality in elderly patients compared with younger patients. OBJECTIVES: To determine clinical differences in elderly and younger patients with acute myocardial infarction. To assess differences in therapies and outcomes between the age groups. METHODS: Over a 3.5-year period, 2482 consecutive adult emergency medical services patients with chest pain received prehospital electrocardiograms and were entered in the Milwaukee Prehospital Chest Pain Database in Milwaukee, Wis. Clinical characteristics that included cardiac history, description of chest pain, time of onset to presentation, and prevalence of acute myocardial infarction were obtained for all patients. Patients with acute infarction were further analyzed in reference to type of infarction (Q wave vs non-Q wave), therapeutic interventions, and mortality. Patients were stratified in 3 age groups: younger than 70 years (younger), 70 years or older (elderly), and 80 years or older (very elderly); differences were compared among the age groups. RESULTS: Even though more than 50% had a history of documented coronary artery disease, elderly patients with ischemic chest pain delayed more than 6 hours in seeking medical assistance after onset of pain. In elderly patients whose chest pain represented an acute myocardial infarction, hospital mortality was double that of younger patients. Thrombolytic therapy reduced hospital mortality by approximately 50% in both younger and elderly patients, although thrombolytic therapies were used in only 17% of the elderly patients compared with 50% of the younger patients (P < .001). Revascularization procedures were also beneficial in elderly patients as well as in younger patients, although this procedure, as with thrombolytic therapy, was less frequently used in elderly patients (48% vs 32%, P < .001). CONCLUSIONS: Effective methods for reducing time delays from onset of chest pain to accessing health care for elderly persons deserve investigation. Physicians should be aware of the benefits of thrombolytic and revascularization therapies in elderly patients with acute myocardial infarction.

Outcomes of cardiopulmonary resuscitation in nursing homes: can we predict who will benefit?

PURPOSE: To determine the benefits of cardiopulmonary resuscitation (CPR) in nursing home patients and assess possible prearrest and arrest predictors of survival. PATIENTS AND METHODS: During a 4-year period (1986 to 1989), consecutive nursing home patients from Milwaukee, Wisconsin, who sustained cardiac arrest and received CPR by paramedics were studied. The patients' prearrest clinical characteristics were determined including age, length of stay in nursing home, medical diagnoses, medications, circumstances surrounding the arrest, laboratory studies, and baseline functional status. Cardiac arrest data were obtained from a paramedic computer data base and included whether the arrest was witnessed, initial cardiac rhythm, and success of CPR. Survival was defined as the discharge of the patient alive from the hospital, and the patient's pre- and post-arrest functional status was compared. Possible predictors of survival were analyzed from the patient's prearrest characteristics and arrest characteristics. RESULTS: Of the total 196 patients who received CPR, 37 (19%) were successfully resuscitated and hospitalized, and 10 (5%) survived to be discharged. However, 27% of patients survived whose arrests were witnessed and who demonstrated ventricular fibrillation at the time of the arrest. In comparison, only 2.3% of all other nursing home patients who received CPR survived (p < 0.0002). Age, mental or functional status, hematocrit, renal dysfunction, pulmonary disease, cancer, and cardiovascular disease were not significant predictors of survival. At the time of hospital discharge, the functional status of the majority (80%) of the survivors was comparable to their prearrest status and 40% of the survivors lived for greater than 12 months. CONCLUSION: We conclude that only a small percentage of nursing home patients who sustain cardiac arrest will benefit from CPR. However, greater than 25% of nursing home patients whose arrest is witnessed and who demonstrate ventricular fibrillation will survive. This is comparable to the survival rate of elderly community-dwelling persons who sustain cardiac arrest. Our data suggest that CPR should be initiated only in nursing home patients whose cardiac arrest is witnessed and should only be continued in patients whose initial documented cardiac rhythm is ventricular fibrillation or ventricular tachycardia.

Comparison of outcome of paramedic-witnessed cardiac arrest in patients younger and older than 70 years.

To obtain further information concerning differences in the mechanism of out-of-hospital cardiac arrest between elderly and younger patients, 381 consecutive patients who experienced out-of-hospital cardiac arrest, and whose arrest was witnessed by paramedics, were studied. In 91% of cases the arrest occurred at the time the patient's cardiac rhythm was monitored. Patients were divided into 2 age groups: elderly patients were greater than 70 years (187) and younger patients were less than 70 years (194). Elderly patients more commonly had a past history of heart failure (25 vs 10%, p less than 0.003) and were more commonly taking digoxin (40 vs 20%, p less than 0.005) and diuretics (35 vs 25%, p less than 0.004). Before the cardiac arrest, elderly patients were more likely to be complaining of dyspnea (53 vs 40%, p less than 0.009), whereas younger patients were more likely to complain of chest pain (27 vs 13%, p less than 0.001). Forty-two percent of younger patients demonstrated ventricular fibrillation as the initial out-of-hospital rhythm associated with the arrest, compared to only 22% of elderly patients (p less than 0.001). Besides patient age, initial cardiac rhythm varied according to the patient's complaint preceding the arrest. Sixty-eight percent of patients with chest pain demonstrated ventricular fibrillation, whereas only 21% of patients with dyspnea demonstrated ventricular fibrillation. Elderly patients could be as successfully resuscitated as younger patients; however, 24% of younger patients survived, compared to only 10% of elderly patients (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Milwaukee Prehospital Chest Pain Project--phase I: feasibility and accuracy of prehospital thrombolytic candidate selection.

This study prospectively determined the feasibility and accuracy of prehospital thrombolytic therapy candidate selection by base station emergency physicians. During a 6-month period, paramedics acquired and transmitted prehospital 12-lead electrocardiograms (ECGs) and then applied a thrombolytic therapy contraindication checklist. Emergency physicians interpreted prehospital ECGs and prospectively selected candidates for thrombolytic therapy. A safety committee of cardiologists reviewed prehospital ECGs, checklists and hospital records to determine accuracy independently. Six hundred-eighty stable adult prehospital patients with a chief complaint of nontraumatic chest pain were initially evaluated. Two hundred forty-one patients were excluded because of (1) unsuccessful electrocardiographic transmission (149), (2) transport to nonparticipating facilities (72), and (3) unavailable medical records (20). No prehospital thrombolytic therapy was administered in this study. Of 439 cases, 91 (21%) had the final diagnosis of acute myocardial infarction, 38 (8.7%) had diagnostic prehospital ECGs, and 12 (2.7%) were selected by emergency physicians as candidates for thrombolytic therapy. Seventy percent of patients with myocardial infarction had checklist exclusions for thrombolytic therapy. Prehospital evaluation increased mean scene time (paramedic arrival on scene to scene departure) by 4 minutes. The median time from chest pain onset to paramedic arrival in patients with myocardial infarction was 60 minutes. The estimated average time saved if prehospital thrombolytic therapy had been available was 101 +/- 81 minutes. The safety committee concluded that acceptable accuracy of emergency physician prehospital electrocardiographic interpretation, checklist and case selection was achieved. It is concluded that emergency physicians can accurately identify candidates for prehospital thrombolytic therapy.

The efficacy of atropine in the treatment of hemodynamically unstable bradycardia and atrioventricular block: prehospital and emergency department considerations.

OBJECTIVE: To determine the efficacy of atropine therapy in patients with hemodynamically compromising bradycardia or atrioventricular block (AVB) in the prehospital and emergency department settings. DESIGN: Retrospective review of prehospital, emergency department, and hospital records. PARTICIPANTS: Prehospital patients with hemodynamically compromising bradycardia or AVB with evidence of spontaneous circulation who received atropine as delivered by emergency medical services personnel (advanced life support level). SETTING: Urban/suburban fire department-based emergency medical service system with on-line medical control serving a population of approximately 1.6 million persons. DEFINITIONS: Hemodynamic instability was defined as the presence of any of the following: ischemic chest pain, dyspnea, syncope, altered mental status, and systolic blood pressure less than 90 mmHg. Bradycardia was defined as sinus bradycardia, junctional bradycardia, or idioventricular bradycardia (grouped as bradycardia) while AVB included first-, second- (types I and II), or third-degree (grouped as AVB). The response that occurred within one minute following each dose of atropine was defined as none, partial, complete, or adverse. MAIN RESULTS: Of 172 patients meeting entry criterion complete data was available for 131 (76.1%) and constitutes the study population. The mean age was 71 years. Fifty-one percent were female. Forty-five patients had AVB and 86 bradycardia. Patients with AVB were more likely to have a presenting systolic blood pressure less than 90 mmHg than those with bradycardia. In the 131 patients, responses to atropine were as follows: 26 (19.8%) = partial, 36 (27.5%) = complete, 65 (49.6%) = none, and 4 (2.3%) = adverse. Patients presenting with bradycardia (compared to AVB) more commonly: (1) received a single dose of atropine; (2) a lower total dose of atropine in the prehospital interval; (3) were more likely to arrive in the ED with a normal sinus rhythm; and (4) were less likely to receive additional atropine or isoproterenol in the ED. Those patients who achieved normal sinus rhythm over the total course of care were likely to have achieved that rhythm during the prehospital interval. There was no difference between groups in the likelihood of leaving the ED with a normal sinus rhythm achieved during the ED interval. Acute myocardial infarction was more common in patients presenting with AVB (55.5%) than with bradycardia (23.2%, P = 0.001). CONCLUSIONS: Approximately one-half of patients who received atropine in the prehospital setting for compromising rhythms had either a partial or complete response to therapy. Adverse responses were uncommon. Those patients who presented with hemodynamically unstable bradycardia to EMS personnel responded more commonly to a single dose and a lower total dose of atropine compared to similar patients with AVB. Those patients who achieve normal sinus rhythm by ED discharge were likely to have achieved it during the prehospital interval.

Electrocardiographic characteristics in EMD.

Little has been written concerning the initial electrocardiographic (EKG) characteristics and/or changes which occur as the result of treatment in the electromechanical dissociation (EMD) patient. The purpose of this retrospective study was to determine predictive indicators of successful resuscitation in EMD by evaluating various EKG parameters. During 72 months, ending December 31st, 1985, there were 503 non-poisoned, prehospital adult cardiac arrest patients whose initial rhythm was EMD. All patients had their initial prehospital EKG rhythm strip evaluated for rhythm type, rate, the presence of P waves, QT interval and QRS interval. In successfully resuscitated patients, the prehospital initial rhythm analysis and the rhythm analysis on emergency department presentation were compared. Successfully resuscitated patients presenting with EMD had significantly faster initial rates, higher incidences of P waves and average QRS and QT intervals shorter than patients not responding to therapy. Furthermore, successfully resuscitated patients had significantly increased heart rates, developed new onset of P waves, and shortened QT intervals in response to treatment. Successfully resuscitated and save patients had average initial and final QRS complex lengths within normal limits. Organized atrial activity on the initial EKG was also correlated with successful resuscitation. No patient with an initial EKG rhythm of second or third degree AV block survived to hospital discharge. No patient who presented to the emergency department with atrial fibrillation survived to hospital discharge. Similarly, supraventricular tachycaydia following resuscitative efforts appeared to be associated with a negative outcome. Rate normalization following treatment was correlated with save rate. Wide complex rhythms without atrial activity were most highly associated with unsuccessful resuscitation. We believe these observed electrocardiographic characteristics and/or changes in response to treatment may have predictive value in evaluating patients with EMD.

Left bundle branch block pattern complicating the electrocardiographic evaluation of acute myocardial infarction.

The ECG diagnosis of ischemic heart disease is made more difficult in the setting of left bundle branch block (LBBB). The ECG diagnosis of prior or remote myocardial infarction (MI) is extremely difficult in this setting. Furthermore, the associated--and expected--ST-segment--T-wave abnormalities of LBBB may mimic acute ischemic change. However, ECG detection of abnormalities arising from acute ischemic cardiac disease in the setting of LBBB can be valuable. Several strategies are available to the emergency physician (EP) to assist in the correct interpretation of this ECG pattern, including: a knowledge of the anticipated ST-segment--T-wave changes of LBBB and, consequently, the ability to recognize ischemic morphologies; the performance of serial ECGs demonstrating dynamic changes encountered in ischemic patients; and a comparison with previous ECGs. Three cases are reported in which an analysis of the 12-lead ECG in the setting of LBBB assisted the EP in establishing the correct diagnosis of acute MI and applying timely, appropriate therapy.

Standard and higher doses of atropine in a canine model of pulseless electrical activity.

OBJECTIVE: To determine whether standard or increased doses of atropine improve the return of spontaneous circulation (ROSC) rate in a canine model of pulseless electrical activity (PEA). METHODS: A prospective, controlled, blinded laboratory investigation was performed using an asphyxial canine cardiac arrest model. After the production of asphyxial PEA, 75 dogs remained in untreated PEA for 10 minutes and then were randomized to receive placebo (group 1) or one of four doses of atropine (group 2, 0.04 mg/kg; group 3, 0.1 mg/kg; group 4, 0.2 mg/kg; group 5, 0.4 mg/kg). All the animals received mechanical external CPR and epinephrine (0.02 mg/kg every 3 minutes) throughout resuscitation. RESULTS: The ROSC rates were not significantly different between the groups (group 1, 73%; group 2, 67%; group 3, 40%; group 4, 47%; group 5, 27%; p = 0.06). The heart rates and hemodynamics during resuscitation were not significantly different between the groups. CONCLUSION: In this canine model of asphyxial PEA cardiac arrest, standard-dose atropine did not improve ROSC rates, compared with placebo. Increasing doses of atropine tended to decrease ROSC rates, compared with placebo and standard-dose atropine.

The electrocardiographic diagnosis of acute myocardial infarction in patients with ventricular paced rhythms.

Use of the ECG for diagnosis of ischemic heart disease is more difficult in the setting of ventricular paced rhythms (VPRs). ST-segment/T-wave configuration are changed by the altered intraventricular conduction associated with ventricular pacing. The anticipated, or expected, morphology in patients with VPRs is one of QRS-complex-ST-segment to T-wave discordance. Several strategies are available to the physician to assist in the correct interpretation of the 12-lead ECG in patients with permanent ventricular pacemakers, including: a knowledge of the anticipated ST-segment-T-wave changes of VPRs and consequently the ability to recognize acute, ischemic morphologies; the performance of serial ECGs or ST-segment trend monitoring demonstrating dynamic changes encountered in acutely ischemic patients; a comparison with previous ECGs; and, if appropriate, an analysis of the native, underlying rhythm. The first strategy, an awareness of the anticipated ST-segment morphologies of VPRs, is the most important and not dependent on additional diagnostic testing, past medical records, or additional expertise in pacemaker function. Two cases are reported in which an analysis of the ECG in the setting of VPR assisted the treating physicians in establishing the correct diagnosis of acute myocardial infarction.

Emergency echocardiographic evaluation of penetrating chest trauma.

Penetrating chest trauma is the most common cause of acute cardiac tamponade. Clinical recognition of this potentially life threatening condition may be difficult despite well described physical signs. Failure to repair the injury causing acute cardiac tamponade may result in sudden decompensation with poor clinical outcome. Emergent use of two-dimensional echocardiography can be an extremely valuable tool in evaluating the presence of cardiac tamponade and directing subsequent clinical management.

Arrhythmias associated with acute myocardial infarction and thrombolysis.

Ninety percent of patients with acute myocardial infarction have some cardiac rhythm abnormality, and approximately twenty-five percent have cardiac conduction disturbance within 24 hours following infarct onset. Almost any rhythm disturbance can be associated with acute myocardial infarction, including bradyarrhythmias, supraventricular tachyarrhythmias, ventricular arrhythmias, and atrioventricular block. With the advent of thrombolytic therapy, it was found that some rhythm disturbances in patients with acute myocardial infarction may be related to successful coronary artery reperfusion. This article addresses the role and treatment of arrhythmias and conduction disturbances that complicate the course of patients with acute infarction and thrombolysis.

Electrocardiographic diagnosis of acute myocardial infarction.

The widely recognized benefits of early diagnosis and treatment of acute myocardial infarction (AMI) have only emphasized the importance of emergency physician (EP) competence in electrocardiographic interpretation. As such, the EP must be an expert in the interpretation of the electrocardiogram (ECG) in the emergency department chest pain center patient. The ECG is a powerful clinical tool used in the evaluation of patients, assisting in making the diagnosis of AMI and other syndromes, selecting appropriate therapies (including thrombolysis and primary angioplasty), securing the location of an adequate inpatient disposition, and predicting the risk of cardiovascular complications and death. This article will discuss the appropriate uses of the ECG in the patient with possible or confirmed AMI and review the typical electrocardiographic findings of AMI, diagnostically confounding patterns, mimickers of infarction, and new techniques.

Planning, implementation, and process monitoring for prehospital 12-lead ECG diagnostic programs.

Prehospital 12-lead electrocardiographic (ECG) diagnostic strategies have been proven feasible and effective, provided they are designed and implemented properly. The authors of this communication have expended considerable time and effort in determining appropriate planning, implementation, and process monitoring necessary for successful implementation of a variety of prehospital diagnostic strategies. Many of these issues may not be obvious to an emergency medical services (EMS) director initiating a 12-lead ECG program. This level of attention to protocol development, education, training, inservice education, coordination of the health-care community, objective program assessment, monitoring and continuous quality improvement can serve as a model for other diagnostic EMS programs that may develop as an expanded role for EMS.

Evaluation of ST segment elevation criteria for the prehospital electrocardiographic diagnosis fo acute myocardial infarction.

STUDY OBJECTIVE: To determine retrospectively the diagnostic accuracy of various ECG ST segment elevation criteria for the prehospital ECG diagnosis of acute myocardial infarction. DESIGN AND SETTING: During a six-month period, paramedics acquired prehospital 12-lead ECGs on adult chest pain patients. Investigators interpreted ECGs independently, retrospectively, and blinded to patient outcome. ECGs were classified as meeting or not meeting the six ST segment elevation criteria regardless of ECG morphology if the criteria were present in two or more anatomically contiguous leads: 1 mm or more ST segment elevation; 2 mm or more ST segment elevation; 1 mm or more ST segment elevation in the limb leads or 2 mm or more ST segment elevation in the precordial leads; and the first three criteria with the simultaneous presence of reciprocal changes. ECGs that did not meet any ST segment elevation criteria were classified as normal, nonspecific ST/T wave changes, abnormal but not ischemic, and ischemic. Hospital charts were reviewed for final cardiac diagnosis. TYPE OF PARTICIPANT: Four hundred twenty-eight stable adult prehospital chest pain patients in whom paramedics acquired prehospital 12-lead ECGs. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Of the 428 cases, 123 (29%) met 1 mm or more ST segment elevation criteria. Sixty-three (51%) of these 123 patients did not have myocardial infarctions. ECG characteristics most frequently associated with these non-myocardial infarction ECGs were left bundle branch block (21%) and left ventricular hypertrophy (33%). The three criteria that required the presence of reciprocal changes had the highest positive predictive values (93% to 95%), with sensitivities ranging from 20% to 33%. The criteria of 1 mm or more ST segment elevation with the simultaneous presence of reciprocal changes had a positive predictive value of 94% and included 18 of the 21 (86%) myocardial infarction patients who had ST segment elevation and received thrombolytic therapy within five hours after hospital arrival. Of the 428 cases, 305 (71%) did not meet any ST segment elevation criteria and had a sensitivity of 81% and a negative predictive value of 49% for the absence of acute myocardial infarction. CONCLUSION: Fifty-one percent of patients whose prehospital 12-lead ECG met 1 mm or more ST segment elevation criteria had non-myocardial infarction diagnoses. ST segment elevation alone lacks the positive predictive value necessary for reliable prehospital myocardial infarction diagnosis. Inclusion of reciprocal changes in prehospital ECG myocardial infarction criteria improved the positive predictive value to more than 90% and included a significant majority (62% to 86%) of acute myocardial infarction patients with ST segment elevation who received thrombolytic therapy within five hours after hospital arrival. ST segment elevation criteria that include reciprocal changes identify patients who stand to benefit most from early interventional strategies.

Continuous pulse oximetry during emergency endotracheal intubation.

STUDY OBJECTIVE: To determine whether continuous pulse oximetry improves the recognition and management of hypoxemia during emergency endotracheal intubation. DESIGN: A prospective, serial 14-month study. SETTING: Emergency department, Level I trauma center. TYPE OF PARTICIPANTS: All adult patients requiring emergency intubation for whom data collection would not compromise patient care. INTERVENTIONS: All samples were obtained from a finger site at a five-second sampling interval and stored in computer memory. Patients were intubated by the nasotracheal or orotracheal route. MEASUREMENTS AND MAIN RESULTS: One hundred ninety-one consecutive adult patients qualified for the study and 211 intubation attempts were analyzed. Hypoxemia (O2 saturation, less than 90%) occurred during an intubation attempt in 30 of 111 nonmonitored versus 15 of 100 monitored attempts (P < .05), and the duration of severe hypoxemia (O2 saturation, less than 85%) was significantly greater for nonmonitored attempts (P < .05). CONCLUSION: Continuous pulse oximetry monitoring reduces the frequency and duration of hypoxemia associated with emergency intubation attempts.

The role of implantable cardioverter defibrillators in non VT/VF sudden deaths.

Implantable cardioverter defibrillator (ICD) therapy has been an impressive success in preventing sudden cardiac death (SCD). Electrocardiographic documentation of SCD in ICD patients has been rare, but usually arrhythmias other than ventricular tachycardia/ventricular fibrillation (VT/VF; asystole and electromechanical dissociation [EMD]) have been implicated. This raises the question whether backup bradycardia pacing can prevent deaths due to asystole and EMD in such patients. We studied the outcome of 88 patients with permanent bradycardia pacemakers and compared them to 500 consecutive nonpacemaker patient controls, sustaining out-of-hospital cardiac arrest and undergoing resuscitation by paramedics. Mean age of the pacemaker patients was 73.5 +/- 10.3 years and 64% males, compared to mean age of 68.2 +/- 6.7 years and 67% males in the control group. Overall success of resuscitation and survival rates were similar. When the documented rhythm was VT/VF or asystole there were no differences in resuscitation or survival rates for the pacemaker or nonpacemaker patients. However, resuscitation rate was significantly higher in pacemaker patients than nonpacemaker patients with EMD: 47% versus 20% (P < 0.03). For EMD, survival rate for the pacemaker patients was 13% compared to 5% in the nonpacemaker patients, but this difference was not statistically significant. Backup bradycardia pacing in future generation devices may improve the outcome of non VT/VF sudden cardiac death in at least some of the ICD recipients.