Evaluation of a prehospital chest pain protocol.

STUDY OBJECTIVES: To evaluate the diagnostic accuracy and outcomes for patients treated by use of a prehospital chest pain protocol (CPP). DESIGN: Consecutive case series for 1 year (1993) of prehospital nontrauma advanced life support (ALS) cases including hospital outcomes. SETTING: Nonurban two-tiered emergency medical services system. PARTICIPANTS: Patients treated under the prehospital CPP or with hospital diagnoses of ischemic heart disease (IHD; ICD-9 between 410 and 414). Patients with cardiac arrest or dysrhythmias were excluded. INTERVENTIONS: Patients were given, by standing orders, ECG monitoring, i.v. access, and sublingual nitroglycerin. Further therapy was guided by on-line medical direction. RESULTS: Of 3,122 ALS nontrauma patients, 620 (20%) were treated with the CPP. All patients underwent ECG monitoring, i.v. access was started in 83%, and 61% received nitroglycerin. Only 55% of patients completed the entire CPP; patients who failed to complete the CPP had the same prevalence of IHD as those who completed it. When compared with hospital diagnosis of IHD, the CPP had a sensitivity of 69% (95% confidence interval [CI], 64% to 74%), a specificity of 87% (95% CI, 86% to 88%), and a positive predictive value of 42%. The positive likelihood ratio of CPP for IHD was 5.31, and the negative likelihood ratio was .36. The hospital mortality rate for all patients was 2.2%; for those with IHD, it was 1.6%. CONCLUSION: This prehospital ALS CPP had good diagnostic accuracy, but only half of patients completed it, and the hospital mortality rate was low. These data challenge the efficacy of the CPP.

Effect of age on prehospital cardiac resuscitation outcome.

To compare resuscitation outcomes in elderly and younger prehospital cardiac arrest victims, we used a retrospective case series over 5 years in rural advanced life support (ALS) units and a University hospital base station. Participants included 563 adult field resuscitations. Excluded were patients with noncardiac etiologies, those less than 30 years old, and those with unknown initial rhythms. Patients were grouped by age. Return of spontaneous circulation (ROSC) and survival to hospital discharge were compared by Yates' chi-square test. ALS treatment of cardiac arrest was by regional protocols and on-line physician direction. Sixty percent (320/532) of patients were over 65 years old. The proportion with initial rhythm ventricular fibrillation (VF) was 50% in the elderly and 48% in younger patients. ROSC was achieved in 18% of elderly and 16% of younger patients; survival was 4% among the elderly and 5% for younger patients. The oldest survivor was 87 years old. Most survivors were discharged, in good Cerebral Performance Categories. There was no difference in outcome by age group when initial cardiac rhythm was considered. Early cardiopulmonary resuscitation (CPR) and ALS and initial rhythm VF were associated with the best resuscitation success. Age has less effect on resuscitation success than other well-known factors such as early CPR and ALS. Advanced age alone should probably not deter resuscitation attempts.

Comparison of interventions in prehospital care by standing orders versus interventions ordered by direct [on-line] medical command.

OBJECTIVE: The aim of this study was to compare the patient care measures provided by paramedics according to standing orders versus measures ordered by direct [on-line] medical command in order to determine the types and frequency of medical command orders. DESIGN: Prospective identification of patient care measures done as part of a prehospital quality assurance program. SETTING: An urban paramedic service in the northeast United States with direct medical command from three local hospitals. PARTICIPANTS: One thousand eight paramedic reports from October 1992 through March 1993. INTERVENTIONS: All patient care interventions recorded as done by standing orders or by direct medical command orders. Errors in patient care were determined by the same criteria as in the prior two studies of the same system. RESULTS: Direct medical command gave orders in 143/1,008 (14.2%) cases. Paramedics performed 2,453/2,624 (93.5%) of the total patient care interventions using standing orders. In 61 cases (6.1%), medical command ordered a potentially beneficial intervention not specified by standing orders or not done by the paramedic. 21/171 (12.3%) command orders were for additional doses of epinephrine or atropine in cardiac arrest cases (where the initial doses had been given under standing orders), and 59/171 (34.5%) were for interventions already mandated or permitted by standing orders. The paramedic error rate was 0.6%, and the medical command error rate was 1.8% (unchanged form the prior study of the same standing-orders system). CONCLUSION: Direct medical command gave orders in 14% of cases in this standing-orders system, but 35% of command orders only reiterated the standing orders. More selective and reduced uses of on-line command could be done in this system with no change in the types or numbers of patient care interventions performed.

Decrease in medical command errors with use of a "standing orders" protocol system.

The purpose of this study was to determine the physician medical command error rates and paramedic error rates after implementation of a "standing orders" protocol system for medical command. These patient-care error rates were compared with the previously reported rates for a "required call-in" medical command system (Ann Emerg Med 1992; 21(4):347-350). A secondary aim of the study was to determine if the on-scene time interval was increased by the standing orders system. Prospectively conducted audit of prehospital advanced life support (ALS) trip sheets was made at an urban ALS paramedic service with on-line physician medical command from three local hospitals. All ALS run sheets from the start time of the standing orders system (April 1, 1991) for a 1-year period ending on March 30, 1992 were reviewed as part of an ongoing quality assurance program. Cases were identified as nonjustifiably deviating from regional emergency medical services (EMS) protocols as judged by agreement of three physician reviewers (the same methodology as a previously reported command error study in the same ALS system). Medical command and paramedic errors were identified from the prehospital ALS run sheets and categorized. Two thousand one ALS runs were reviewed; 24 physician errors (1.2% of the 1,928 "command" runs) and eight paramedic errors (0.4% of runs) were identified. The physician error rate was decreased from the 2.6% rate in the previous study (P < .0001 by chi 2 analysis). The on-scene time interval did not increase with the "standing orders" system.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of two systems for quality assurance of prehospital advanced life support services.

INTRODUCTION: The need for quality assurance (QA) systems for review of prehospital advanced life support (ALS) care has long been recognized. However, there only have been limited published studies on the operation and cost of QA systems for prehospital care. A number of different systems currently are in use, and the relative effectiveness of different QA systems has not been well determined. OBJECTIVE: The aim of this study was to compare the personnel work-time and costs of two different systems of QA for prehospital ALS services, and thereby determine which type of system was more cost-effective in the generation of QA reports. METHODS: The quality assurance program (System 1) for three independent ALS services in a rural/suburban area and the QA program (System 2) for a nearby urban ALS service were compared. Data recorded included the training level and number of hours per year devoted exclusively to QA activities by different personnel. The annual costs for other aspects of the QA systems and apportioned salary costs for time spent on QA work were recorded. RESULTS: System 1, a computer-based system, utilized 1,116 hours per year of personnel time and required [US]$17,662 in total costs per year (average cost per run reviewed of $4.38). System 2 (a manual system) utilized 569 hours per year of personnel time and had an annual cost of [US]$8,361 (or $2.15 per run reviewed). System 1 generated 852 reports per year (21% of runs) about non-compliance with protocols or charting deficiencies. System 2 generated 284 reports per year (7.3% of runs) for similar events. CONCLUSIONS: Either a computer-based or "manual" system for QA of prehospital ALS services can be utilized. A computer-based system requires more personnel time and is more expensive, but generates more reports per year than does the manual system. A computer-based system more readily can retrieve run report data for further review.

Medication mishaps. Avoiding inappropriate use of prehospital meds.

Although we believe in the usefulness and effectiveness of certain medications used in prehospital care, there actually have been few studies conducted that prove the efficacy of medications in this environment. Use of prehospital medications should be carefully considered by EMS providers. Medications should be used when the diagnosis or cause of symptoms is clear, the medication is clearly effective in treating them, the side effects or complications are minimal, and the transport time is sufficient to allow the medication to take effect.

Effects of prehospital medications on mortality and length of stay in congestive heart failure.

HYPOTHESIS: Prehospital medications for congestive heart failure should affect hospital outcomes (survival and length of stay). STUDY DESIGN: In a retrospective case series, hospital outcomes were compared for patients treated with prehospital nitroglycerin, furosemide, and/or morphine (252) versus those given no medications (241). SETTING: A rural/suburban emergency medical services system (population 140,000) served by three paramedic units. PARTICIPANTS: Four hundred ninety-three consecutive cases of congestive heart failure or pulmonary edema were identified by hospital discharge diagnosis from a data base of 8,315 paramedic transports with known outcome. INTERVENTIONS: Oxygen was given by protocol to 489 patients. Other medications were given by order of on-line physician medical command. RESULTS: Overall mortality was 10.9% (54 of 493). Treated and untreated patients were comparable in age, sex, cardiac rhythms, prior use of cardiac medications, and response and scene times; mortality was reduced in treated versus untreated patients (odds ratio for improved survival, 2.51; 95% confidence interval, 1.37 to 4.55; P less than .01). Positive treatment effect was greatest for 58 nonhypotensive, critical patients (odds ratio for survival, 10.25; P less than .01). No single drug combination was unique in terms of treatment benefit. Patients treated in the field received medications 36 minutes earlier than patients first treated in the emergency department. No survival benefit was evidence for noncritical, nonhypotensive patients, and patients with final diagnoses of asthma, chronic obstructive pulmonary disease, pneumonia, or bronchitis had a higher than expected mortality if erroneously treated for congestive heart failure. Differences in hospital length of stay were not significant for any group. CONCLUSION: Prehospital medications improve survival in congestive heart failure, especially in critical patients. More than one combination of medications seems effective, and early treatment is associated with improved survival. However, these medications appear to increase mortality in patients misdiagnosed in the field. Factors used in paramedica and medical command assessments require further study.

Medical command errors in an urban advanced life support system.

STUDY OBJECTIVE: The aim of this study was to assist in focusing educational efforts for command physicians by identifying the most common types of errors made by on-line medical command. DESIGN: Retrospective survey of prehospital advanced life support (ALS) trip sheets. SETTING: An urban ALS paramedic service with on-line physician medical command rotating on a monthly basis among three hospitals. PARTICIPANTS: From September 1988 through December 1990, all ALS run sheets were reviewed as part of an ongoing quality assurance program. Cases were identified as deviating from regional emergency medical services protocols as judged by agreement of three physician reviewers. Cases were excluded if all three reviewers did not agree that the command rendered was inappropriate. INTERVENTIONS: Command errors were identified from the prehospital ALS run sheets and categorized. RESULTS: One hundred ninety-four command errors in 167 cases were identified from 3,839 runs (4.4% of all runs). Six types of errors accounted for 80% of the total errors, with the most common error (34%) being failure to address the possibility of hypoglycemia with altered level of consciousness. Error rate decreased from 7.9% to 2.6% of total runs during the study period. CONCLUSION: To reduce the medical command error rate, physician education should be directed at the six problem areas identified. Ongoing quality assurance review of medical command may result in a decrease of the command error rate.

Prehospital administration of inhaled metaproterenol.

STUDY OBJECTIVES: We conducted a study of the prehospital use of inhaled metaproterenol. DESIGN, SETTING, TYPE OF PARTICIPANTS, AND INTERVENTIONS: Advanced life support (ALS) providers were trained with a standardized curriculum to identify patients likely to benefit from prehospital inhaled metaproterenol administration. Unit doses of metaproterenol were used in a small-volume nebulizer. We prospectively included 122 patients in an initial study (71 men; age, 63 +/- 19 years) to evaluate the safety and effectiveness of metaproterenol in the field, and 150 patients (including the original 122) in an additional study to evaluate patient selection criteria. MEASUREMENTS AND MAIN RESULTS: The treatments resulted in an increase in peak flows, a decrease in respiratory rates, and no change in heart rates. In 62% of patients, the increase in peak flow exceeded 15%. Wheezing improved in 59% of the patients, worsened in 4%, and did not change in the remainder. Air entry by auscultation improved subjectively in 59% of patients. Mild tremor occurred in 8% of patients, moderate tremor occurred in 1%, and no tremor occurred in the remainder. Significant dysrhythmias did not occur. CONCLUSIONS: ALS providers correctly identified patients for this therapy. No technical problems were encountered in the field with this treatment approach. We conclude that ALS providers can be taught to identify patients likely to benefit from inhaled metaproterenol, that inhaled metaproterenol can be administered in the field, and that metaproterenol is both safe and effective when used in the prehospital setting.

Theoretical effects of fluid infusions during cardiopulmonary resuscitation as demonstrated in a computer model of the circulation.

Recent studies have shown the potential adverse effects of venous volume loading on blood flow during closed chest cardiopulmonary resuscitation (CPR). To examine the effect of arterial and venous infusions, we employed a published computer simulation of the circulation during CPR. This model uses computer simulated electrical networks to model the heart and great vessels. CPR was modeled with compressions at a rate of 80/min and a force of 80 mmHg. Fluid infusions, simulated as current pulses into the abdominal aorta and superior vena cava, were given to measure their effect on myocardial and cranial blood flow. With 600 ml/min infusions into the abdominal aorta, there was a 12% peak increase in myocardial flow and a 3.8% peak increase in cranial flow. Every 100 ml/min increase in infusion from 0 to 900 ml/min produced a 1.4 ml/min linear increase in myocardial flow and a 4.2 ml/min linear increase in cranial flow. In agreement with previous CPR model studies, simulated vasoconstriction of abdominal and lower extremity vessels resulted in increased myocardial and cranial flows. As resistance of these vessels was increased, abdominal aortic infusions resulted in greater flow augmentations. In contrast to arterial results, infusions at 600 ml/min into the vena cava resulted in a 2.2% decrease in myocardial flow and a 0.62% decrease in cranial flow. Rise and fall times for initiation and cessation of flow augmentations were equal to four compression cycles. We conclude that these findings demonstrate the theoretical benefits of rapid arterial infusions during CPR with increases in myocardial and cranial blood flow. This method may provide an early temporary adjunct to myocardial perfusion during CPR.

Testing visual acuity in the emergency department: a simple method of correcting refractive error by using the hand-held ophthalmoscope.

The assessment of visual acuity is an important part of the emergency ophthalmologic examination. The ability to distinguish refractive error from other etiologies of decreased visual acuity is necessary to adequately evaluate visual function. A readily available source of corrective lenses can be found in the hand-held ophthalmoscope. These lenses can be used to identify and quantitate refractive errors and assist in identifying serious ocular pathology.

Computer simulation of cardiopulmonary resuscitation: computer analysis of a simple electrical model of the circulation.

Extensive research is being conducted to study the mechanism of blood flow during cardiopulmonary resuscitation (CPR). Recently, work has been published using a simple electrical model of the circulation to simulate the hemodynamics of CPR. This analog was a hard-wired circuit consisting of the heart and great vessels modeled as a resistive-capacitive network, pressure as voltage, blood flow as current, blood inertia as inductance and vascular valves as diodes. Such a model is useful for examining the physiology of various methods and techniques of CPR administration. In this investigation, a general purpose circuit simulation program, SPICE Version 2G.6, was used to analyze previously published CPR models. With minor modifications, the program was fully able to simulate the hard-wired circuits. The program is very flexible, allowing for easy model modification and a wide range of parameter values. In addition, the program offers the advantages of increased accuracy and low cost. Suggested future applications are for rapid evaluation of new CPR concepts.

Synthesis and processing of the precursor to the major core protein of adenovirus type 2.

An isopycnic Metrizamide-detergent gradient system was developed in which the newly synthesized precursor (polypeptide P-VII) to the major core protein of adenovirus type 2 (polypeptide VII) was confined to a spectrum of complexes with densities equal to or higher than that of adenovirions. The majority of the newly synthesized P-VII was, at the beginning of the logarithmic period of virus production, present as an entity of protein density. This pool of P-VII was efficiently depleted. P-VII was also associated with high-molecular-weight structures of intermediate density, sharing some properties with empty capsids or incomplete particles. The transfer of P-VII from the intermediate-density region was not quantitative, and only particles of true virion density subsequently contained polypeptide VII. No structures equivalent to the core structure of disrupted virions or identical to incomplete particles were detected in this system. A temperature-dependent transition of radioactivity from polypeptide P-VII into polypeptide VII was also detectable after in vitro incubation of P-VII-containing complexes. Addition of Ad2-infected cell extracts was required for processing of complexes derived from regions of protein density, whereas P-VII was processed spontaneously upon incubation in complexes of virion density.