Heart-to-heart talk. Roundtable discussion.

This past August the American Heart Association (AHA) released a major revision of its recommendations for emergency cardiovascular care (ECC). The 2000 guidelines simplify CPR techniques for the layperson and strongly promote the use of community early defibrillation. What repercussions can we expect from these changes? We asked five experts to join a roundtable discussion of the BLS aspects of these new guidelines. Their conversation follows.

Prehospital 12-lead ECG. An evolving standard of care in EMS systems.

The prehospital 12-lead ECG has evolved from an unproven "luxury" item to a standard of care for contemporary EMS systems. The initial impact of transmitted ECGs was to dramatically reduce door-to-drug or door-to-lab intervals by giving a "heads-up" to the receiving facility. With better reperfusion drugs and techniques and the development of committed cardiac specialty centers, the prehospital ECG now plays an important role in screening for field therapy or directing patients to the most appropriate facility for definitive care. EMS systems should critically evaluate their role in establishing a community-wide standard for management of patients with acute coronary syndromes.

Resuscitation in the out-of-hospital setting: medical futility criteria for on-scene pronouncement of death.

The complete and irreversible cessation of life is often difficult to determine with complete confidence in the dynamic environment of out-of-hospital emergency care. As a result, resuscitation efforts often are initiated and maintained by emergency medical services (EMS) providers in many hopeless situations. Medical guidelines are reviewed here to aid EMS organizations with respect to decisions about: 1) initiating or waiving resuscitation efforts; 2) the appropriate duration of resuscitation efforts; and 3) recommended procedures for on-scene or prehospital pronouncement of death (termination of resuscitation). In cases of nontraumatic cardiac arrest, few unassailable criteria, other than certain physical signs of irreversible tissue deterioration, exist for determining medical futility at the initial encounter with the patient. Thus, the general medical recommendation is to attempt to resuscitate all patients, adult or child, in the absence of rigor mortis or dependent lividity. Conversely, wellfounded guidelines now are available for decisions regarding termination of resuscitation in such patients once they have received a trial of advanced cardiac life support. In practice, however, the final decision to proceed with on-scene pronouncement of death for these patients may be determined more by family and provider comfort levels and the specific on-scene environment. For patients with posttraumatic circulatory arrest, the type of injury (blunt or penetrating), the presence of vital signs, and the electrocardiographic findings are used to determine the futility of initiating or continuing resuscitation efforts. In general, patients who are asystolic on-scene are candidates for on-scene pronouncement, regardless of mechanism. With a few exceptions, blunt trauma patients with a clearly associated mechanism of lethal injury are generally candidates for immediate cessation of efforts once they lose their pulses and respirations. Regardless of the medical futility criteria, specialized training of EMS providers and targeted related testing of operational issues need to precede field implementation of on-scene pronouncement policies. Such policies also must be modified and adapted for local issues and resources. In addition, although the current determinations of medical futility, as delineated here, are important to establish for societal needs, the individual patient's right to live must be kept in mind always as new medical advances are developed.

Results of report cards for patients with congestive heart failure depend on the method used to adjust for severity.

BACKGROUND: The validity of outcome report cards may depend on the ways in which they are adjusted for risk. OBJECTIVES: To compare the predictive ability of generic and disease-specific survival prediction models appropriate for use in patients with heart failure, to simulate outcome report cards by comparing survival across hospitals and adjusting for severity of illness using these models, and to assess the ways in which the results of these comparisons depend on the adjustment method. DESIGN: Analysis of data from a prospective cohort study. SETTING: A university hospital, a Veterans Affairs (VA) medical center, and a community hospital. PATIENTS: Sequential patients presenting in the emergency department with acute congestive heart failure. MEASUREMENTS: Unadjusted 30-day and 1-year mortality across hospitals and 30-day and 1-year mortality adjusted by using disease-specific survival prediction models (two sickness-at-admission models, the Cleveland Health Quality Choice model, the Congestive Heart Failure Mortality Time-Independent Predictive Instrument) and generic models (Acute Physiology and Chronic Health Evaluation [APACHE] II, APACHE III, the mortality prediction model, and the Chadson comorbidity index). RESULTS: The community hospital's unadjusted 30-day survival rate (85.0%) and the VA medical center's unadjusted 1-year survival rate (60.9%) were significantly lower than corresponding rates at the university hospital (92.7% and 67.5%, respectively). No severity model had excellent ability to discriminate patients by survival rates (all areas under the receiver-operating characteristic curve < 0.73). Whether the VA medical center, the community hospital, both, or neither had worse survival rates on simulated report cards than the university hospital depended on the prediction model used for adjustment. CONCLUSIONS: Results of simulated outcome report cards for survival in patients with congestive heart failure depend on the method used to adjust for severity.

Pharmacologic treatment of cardiac arrest.

Antiarrhythmic drugs currently recommended in the American Heart Association's Advanced Cardiac Life Support (ACLS) guidelines for the treatment of cardiac arrest have not been proved in controlled clinical trials to improve survival in patients with ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT). Intravenous amiodarone is a promising agent for the treatment of VF and VT. Based on available evidence, amiodarone should be considered for use in patients with shock-refractory ventricular arrhythmias.

An international comparison of physicians' judgments of outcome rates of cardiac procedures and attitudes toward risk, uncertainty, justifiability, and regret.

OBJECTIVE: Compare U.K. and U.S. physicians' judgments of population probabilities of important outcomes of invasive cardiac procedures; and values held by them about risk, uncertainty, regret, and justifiability relevant to utilization of cardiac treatments. DESIGN: Cross-sectional study. SETTING: University hospital and VA medical center in the United States; two teaching hospitals in the United Kingdom. PARTICIPANTS: 171 housestaff and attendings at U.S. teaching hospitals; 51 physician trainees and consultants at U.K. hospitals. MEASURES: Judgments of probabilities of severe complications and deaths due to Swan-Ganz catheterization, cardiac catheterization, percutaneous transluminal coronary angioplasty (PTCA), and coronary artery bypass grafting (CABG); judgments of malpractice risks for case vignettes; Nightingale's risk-aversion instrument; Gerrity's reaction-to-uncertainty instrument; questions about need to justify decisions; responses to case vignettes regarding regret. RESULTS: The U.S. physicians judged rates of two bad outcomes of cardiac procedures (complications due to cardiac catheterization; death due to CABG) to be significantly higher (p < or = 0.01) than did the U.K. physicians (U.S. medians, 5 and 3.5, respectively; U.K. medians 3 and 2). The median ratio of (risk of malpractice suit I error of omission)/(risk of suit I error of commission) judged by U.K. physicians, 3, was significantly (p=0.0006) higher than that judged by U.S. physicians, 1.5. The U.K. physicians were less often risk-seeking in the context of possible losses than the U.S. physicians (odds ratio for practicing in the U.K. as a predictor of risk seeking 0.3, p=0.003). The U.K. physicians had significantly more discomfort with uncertainty than did the U.S. physicians, as reflected by higher scores on the stress scale (U.K. median 48, U.S. 42, p=0.0001) and the reluctance-to-disclose-uncertainty scale (U.K. 40, U.S. 37, p < 0.0001) of the Gerrity instrument. There was no clear international difference in perceived need to justify decisions, or in regret. CONCLUSIONS: The results were not clearly consistent with the uncertainty hypothesis that international practice variation is due to differences in judged rates of outcomes of therapy or with the imperfect-agency hypothesis that practice variation is due to differences in physicians' personal values. The causes and implications of practice variations remain unclear.

Synchronization of timepieces to the atomic clock in an urban emergency medical services system.

STUDY OBJECTIVE: Erroneous time documentation of emergency treatment caused by the variation in the accuracy of timepieces has profound medical, medicolegal, and research consequences. The purpose of this study was to confirm the variation of critical timepiece settings in an urban emergency care system noted in previous studies and to implement and monitor the results of a prospective program to improve time synchronization. METHODS: Timepieces (n = 393) used by firefighters, paramedics, and emergency physicians and nurses were randomly sampled immediately before and at two time intervals (1 and 4 months) after attempted synchronization to the US atomic clock standard. The setting on each timepiece was compared with the atomic clock. From the data, a mathematical simulation estimated the number of time-related documentation errors that would occur in 2,500 simulated cardiac arrest cases using timepieces with accuracy similar to those found in the EMS system before and after attempted synchronization. RESULTS: Before attempted synchronization, the timepieces had a mean error of 2.0 (95% confidence interval 1.8 to 2.3) minutes. One month after attempted synchronization, the mean error decreased significantly to .9(.8 to 1.1) minute. However, it increased to 1.7 (1.5 to 1.9) minutes within 4 months. Mathematical simulation before attempted synchronization predicted that 93% of cardiac arrest cases would contain a documentation error of 2 minutes or more and that 41% of cases would contain a documentation error of 5 minutes or more. Attempted synchronization cut the 2-minute documentation error rate in half and reduced the 5-minute documentation error rate by three fourths. However, the error rates were predicted to return to baseline 4 months after attempted synchronization. CONCLUSION: Emergency medical timepieces are often inaccurate, making it difficult to reconstruct events for medical, medicolegal, or research purposes. Community synchronization of timepieces to the atomic clock can reduce the problem significantly, but the effects of a one-time attempted synchronization event are short-lived.

Physicians' judgments of the risks of cardiac procedures. Differences between cardiologists and other internists.

OBJECTIVES: The authors compared judgments of the population risks of invasive cardiac procedures made by cardiologists and other internal medicine physicians. Our main hypotheses were that cardiologists' judgments would differ from those made by the other physicians and that cardiologists' judgments would be more accurate than those of other physicians. METHODS: This was a cross-sectional survey of senior staff and physician-trainees at two teaching hospitals affiliated with a US medical school, Emergency Department physicians at a community hospital in the same metropolitan area, and senior staff and trainees at two teaching hospitals affiliated with a UK school. Judgments of the risks of severe morbidity and death due to Swan-Ganz catheterization, cardiac catheterization, percutaneous coronary angioplasty, and coronary artery bypass grafting were assessed. RESULTS: Nineteen cardiologists judged the risks of severe morbidity due to all procedures and the risks of death due to all procedures except coronary artery bypass grafting to be significantly lower than did the 78 other internists. Cardiologists more frequently made accurate judgments of the rates of morbidity and death due to cardiac catheterization than did the other internists; other internists more frequently made accurate judgments for the rates of morbidity due to Swan-Ganz catheterization. CONCLUSIONS: Disagreements about the risks of procedures may arise from a paucity of published data, or from an over-supply of confusing data.

Physicians' survival predictions for patients with acute congestive heart failure.

BACKGROUND: Current guidelines suggest that patients with low likelihoods of survival may be excluded from intensive care. Patients with new or exacerbated congestive heart failure are frequently but not inevitably admitted to critical care units. OBJECTIVE: To assess how well physicians could predict the probability of survival for acutely ill patients with congestive heart failure, and in particular how well they could identify patients with small chances of survival. METHODS: This was a prospective cohort study done in the emergency departments of a university hospital, a Veterans Affairs medical center, and a community hospital. The study population was consecutive adults for whom new or exacerbated congestive heart failure, diagnosed clinically, was a major reason for the emergency department visit. Physicians caring for the study patients in the emergency departments recorded their judgments of the numeric probability that each patient would survive for 90 days and for 1 year. The patients vital status at 90 days and 1 year was ascertained by multiple means, including interview, chart review, and review of hospital and state databases. RESULTS: By calibration curve analysis, the physicians underestimated survival probability at both 90 days and 1 year, particularly for patients they judged to have the lowest probabilities of survival. Their predictions had modest discriminating ability (receiver operating characteristic curve areas, 0.66 [SE = 0.020] for 90 days; 0.63 [SE = 0.017] for 1 year). The physicians identified only 15 patients they judged to have a 90-day survival probability of 10% or less, whose survival rate was actually 33.3%. CONCLUSIONS: Physicians have great difficulty predicting survival for patients with acute congestive heart failure and cannot identify patients with poor chances of survival. Current triage guidelines that suggest patients with poor chances of survival may be excluded from critical care may be impractical or harmful.

Inappropriate electrical countershocks by an automated external defibrillator.

A 79-year-old man who was in normal sinus rhythm with a palpable pulse was inappropriately shocked twice by a fully automated external defibrillator. The second shock resulted in ventricular tachycardia. The device then countershocked a third time, restoring normal sinus rhythm. The problem occurred primarily because the rescuers did not follow the device's instructions warning against applying the device in analysis mode to a patient with a palpable pulse, and they attempted to analyze the rhythm in a moving vehicle. Motion artifact and T waves that were relatively tall compared with the QRS amplitude were misinterpreted as ventricular fibrillation by the device. This example of inappropriate countershocks delivered by rescuers using a fully automated device illustrates the importance of proper training and continuing education.

Multicenter study of a portable, hand-size, colorimetric end-tidal carbon dioxide detection device.

STUDY OBJECTIVES: To evaluate continuous, semiquantitative end-tidal carbon dioxide (ETCO2) monitoring in the prehospital and emergency department setting for confirming proper endotracheal tube placement and assessing prognosis and blood flow during CPR. TYPE OF PARTICIPANTS: Adult patients were included if an endotracheal tube was inserted by prehospital care providers or emergency physicians for cardiac arrest, respiratory arrest, respiratory insufficiency, or airway protection. DESIGN AND INTERVENTIONS: A small, portable, colorimetric ETCO2 detector was attached to the endotracheal tube immediately after each attempted endotracheal tube insertion. The color of the detector membrane was noted at the seventh breath following intubation. The color also was noted and recorded if there was return of spontaneous circulation (defined as a palpable pulse) immediately prior to and following conversion from manual to mechanical CPR. Survival to hospital admission was used as an end point to assess the prognostic value of the initial ETCO2 reading. MAIN RESULTS: A total of 227 patients (144 with cardiopulmonary arrest) were studied. In the 83 patients intubated but not in cardiopulmonary arrest, a reading on the ETCO2 detector signifying more than 0.5% ETCO2 was 100% sensitive and 93% specific in detecting proper endotracheal tube placement (100% specific with the endotracheal tube cuff inflated). In cardiac arrest patients, a longer period of estimated arrest appeared to be associated with a lower ETCO2 detector reading. A reading signifying more than 0.5% ETCO2 was 69% sensitive and 100% specific in detecting proper endotracheal tube placement. After proper endotracheal tube placement, all cardiac arrest patients who survived to hospital admission had an initial ETCO2 measurement signifying more than 0.5% ETCO2. Return of spontaneous circulation was usually accompanied by an improved ETCO2 value. Mechanical CPR always produced an ETCO2 value that was as high or higher than that produced by manual CPR. CONCLUSION: The colorimetric ETCO2 device is highly accurate for confirming endotracheal tube position in nonarrest patients. CONCLUSION: The colorimetric ETCO2 device is highly accurate for confirming endotracheal tube position in nonarrest patients. In cardiac arrest patients, a reading signifying more than 0.5% ETCO2 confirms correct endotracheal tube placement, while a value signifying less than 0.5% ETCO2 during resuscitation suggests that something is wrong (eg. esophageal intubation, inadequate circulatory flow, prolonged down-time interval, hypothermia, or significant ventilation/perfusion mismatch).

Multi-agency, prehospital evaluation of the pharyngeo-tracheal lumen (PTL) airway.

INTRODUCTION: The purpose of this study was to assess subjectively the performance of the pharyngeo-tracheal lumen (PTL) airway in a multi-agency, prehospital emergency medical service (EMS) environment. METHODS: Data were recorded by the EMS provider on 167 [corrected] adult patients (age range 16-92 years) in whom a PTL or endotracheal (ET) airway insertion was attempted. Analysis of variance and Fisher's Exact tests were used for statistical analysis. RESULTS: There were no significant differences between the PTL and ET groups, either in patient demographics or in rates of successful ventilation with either airway overall or in trauma-related versus non-trauma-related cases, male versus female patients, or volunteer versus paid EMS providers. Basic life support (BLS) providers were able to ventilate successfully with the PTL as frequently as were ALS providers using the ET tube. CONCLUSIONS: The PTL appears to be a useful primary airway for BLS providers and for ALS providers who are called upon infrequently to manage an airway acutely. The PTL also may be used as an alternate airway for ALS providers when tracheal intubation cannot be accomplished. Further study is needed to define the effectiveness of the PTL in the management of patients with trauma-related injuries.

Dose-response evaluation of oral labetalol in patients presenting to the emergency department with accelerated hypertension.

STUDY OBJECTIVE: Dose-response evaluation of oral labetalol (100, 200, or 300 mg) on heart rate and systemic blood pressure in emergency department patients with hypertensive urgency (diastolic blood pressure, 110 to 140 mm Hg, and no end-organ evidence of hypertensive emergency). METHODS: This acute-treatment, dose-ranging study used a randomized, double-blind, parallel design. Patients with supine diastolic blood pressure of 110 to 140 mm Hg after 30 minutes of bedrest received an oral dose of labetalol. Supine blood pressure and heart rate were measured manually and recorded hourly for four hours after dose. Diastolic blood pressure of 100 mm Hg or less or a 30-mm Hg reduction in diastolic blood pressure was considered a treatment success. RESULTS: Two hundred fifty-five patients were evaluated for inclusion, and 36 patients (19 women and 17 men; mean age, 44 years; age range, 23 to 67 years) were studied. The most frequent reason for exclusion was a spontaneous decrease in diastolic blood pressure to less than 110 mm Hg (31%) with bedrest. There were 12 patients in each treatment group. Compared with baseline, the 100-mg dose significantly (P less than .05) reduced heart rate at three and four hours after dose, and the 300-mg dose significantly (P less than .05) reduced heart rate at one, two, and three hours after dose; the 200-mg dose did not significantly affect heart rate. All doses produced a significant decrease in systolic and diastolic blood pressures at one, two, three, and four hours after dose compared with baseline. There were no statistically significant differences between treatment groups with regard to systolic or diastolic blood pressure or heart rate at baseline or one, two, three, or four hours after dose. At two hours after dose, diastolic blood pressure control was observed in 75%, 58%, and 67% of patients receiving 100, 200, and 300 mg, respectively (P = .903). At four hours after dose, diastolic blood pressure control was observed in 50%, 64%, and 67% of patients receiving 100, 200, and 300 mg, respectively (P = .755). A comparison of treatment success rates between the two time periods showed a waning of response with the 100-mg dose of labetalol at hour 4 compared with hour 2 (P less than .05). No adverse effects were observed. CONCLUSION: Labetalol provides safe and effective treatment for hypertensive urgencies when administered orally in doses of 100 to 300 mg.

Clinical prediction rule for pulmonary infiltrates.

OBJECTIVE: To derive and validate a clinical rule for predicting pneumonic infiltrates in adult patients with acute respiratory illness. DESIGN: Prevalence studies in three settings. SETTING: Emergency departments of the University of Illinois Hospital at Chicago, the University of Nebraska Medical Center at Omaha, and the Medical College of Virginia at Richmond. PATIENTS: Symptoms, signs, comorbidity data, and chest roentgenogram results were recorded for 1134 patients from Illinois (the derivation set), 150 patients from Nebraska, and 152 patients from Virginia (the validation sets). All patients presented to the emergency department and had a chest roentgenogram to evaluate fever or respiratory complaints. MEASUREMENTS AND MAIN RESULTS: Within the training set, temperature greater than 37.8 degrees C, pulse greater than 100 beats/min, rales, decreased breath sounds, and the absence of asthma were identified as significant predictors of radiographically proved pneumonia in a stepwise logistic regression model (P = 0.001). The logistic rule discriminated patients with and without pneumonia in the training set with a receiver operating characteristic (ROC) area of 0.82. In the validation sets, the rule discriminated pneumonia and nonpneumonia with ROC areas of 0.82 and 0.76 after adjusting for differences in disease prevalence (P greater than 0.2 compared with the training set). The predicted probability of having pneumonia for patients with different clinical findings corresponded closely with the incidence of pneumonia among patients with such findings in the three settings. CONCLUSIONS: Among adults presenting with acute respiratory illness, a prediction rule based on clinical findings accurately discriminated patients with and without radiographic pneumonia, and was used in two other samples of patients without significant decrement in discriminatory ability. This rule can be used by physicians to develop more effective strategies for detecting pneumonia and for helping to determine the need for radiologic study among patients with acute respiratory disease.

Influence of an antacid containing aluminum and magnesium on the pharmacokinetics of cefixime.

Interaction studies in dogs have indicated that antacids significantly decrease the oral bioavailability of cefixime. Twelve healthy adult male volunteers participated in a randomized, four-way crossover trial to evaluate the influence of an aluminum-magnesium antacid (Maalox; 20 ml) on the pharmacokinetics of cefixime (400 mg). Regimens were (i) cefixime alone; (ii) cefixime simultaneous with antacid; (iii) cefixime 2 h before antacid; and (iv) cefixime 2 h after antacid. Serial blood and urine samples were collected over a 24-h period following each dose of cefixime. There was a 1-week washout interval between regimens. Cefixime concentrations in serum and urine were analyzed by high-performance liquid chromatography. Maximum cefixime concentrations in serum for regimens i through iv were (mean +/- standard deviation) 4.9 +/- 1.4, 5.7 +/- 1.3, 5.1 +/- 1.0, and 5.5 +/- 1.5 micrograms/ml, respectively. Corresponding values for area under the serum concentration-time curve extrapolated to infinity were 38.3 +/- 14.5, 42.8 +/- 13.9, 38.5 +/- 9.8, and 41.6 +/- 16.7 micrograms.h/ml. There was a trend toward increased concentrations in serum and area under the curve of cefixime when it was administered concomitantly with antacid; however, these differences were not statistically significant (P greater than 0.05; analysis of variance). We conclude that single-dose administration of an aluminum-magnesium antacid does not significantly decrease the oral bioavailability of cefixime.

Dose-dependent vasopressor response to epinephrine during CPR in human beings.

The optimal dose of epinephrine during CPR in human beings is unknown. We studied ten prehospital cardiac arrest patients (six men and four women; mean age, 54 +/- 5 years) to determine the vasopressor response and change in the end-tidal carbon dioxide concentration (PetCO2) after incremental (1-, 3-, and 5-mg) doses of IV epinephrine given five minutes apart during closed-chest CPR. All patients were in ventricular fibrillation on arrival of the paramedics and did not respond to standard advanced cardiac life support. CPR was performed with a computerized Thumper; all patients were intubated and ventilated at 12 times a minute at an FiO2 of 0.8. Radial artery pressure was measured with a 20 angiocath inserted by radial artery cutdown. Paramedic response time was 4.3 +/- 0.5 minutes; elapsed time to emergency department arrival was 40.0 +/- 9.5 minutes. Initial blood gases were paO2, 241 +/- 50 mm Hg; pH, 7.23 +/- 0.08; paCO2, 27 +/- 5 mm Hg; and HCO3, 11 +/- 2 mEq/L. Baseline systolic and diastolic blood pressures were 47 +/- 5 mm Hg and 18 +/- 2 mm Hg, respectively. Systolic blood pressure was directly related to the dose of epinephrine (P less than .0001), rising to 69 +/- 7 mm Hg, 74 +/- 8 mm Hg, and 85 +/- 8 mm Hg after 1-, 3-, and 5-mg doses of epinephrine, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of applied chest compression force on systemic arterial pressure and end-tidal carbon dioxide concentration during CPR in human beings.

Twelve adult (nine men and three women) cardiac arrest patients were studied as they received CPR by a computerized Thumper to determine the influence of the applied chest compression force on blood flow (as assessed by the end-tidal carbon dioxide concentration) and arterial pressure. At the end of a resuscitation when the decision was made by the senior physician to cease resuscitative efforts, the applied force on the CPR Thumper was decreased from 140 to 0 pound-force (lbf) in 20-lbf increments at 30-second intervals. Radial artery cutdown blood pressure and end-tidal carbon dioxide (ETCO2) were recorded continuously. Arterial systolic blood pressure was linearly related (r = .59, P less than .0001) to applied force (systolic blood pressure, 31 +/- 6 mm Hg at 20 lbf to 60 +/- 7 mm Hg at 140 lbf). ETCO2 (r = .42, P less than .0001) was also linearly related to applied force (ETCO2, 0.7 +/- 0.1% at 20 lbf to 1.5 +/- 0.2% at 140 lbf). Diastolic pressure did not change significantly with change in applied force (17 +/- 2 mm Hg from 20 to 140 lbf). Our findings indicate that higher compression force than that currently recommended may improve arterial systolic pressure and flow in human beings receiving closed-chest compression during CPR.