Accuracy of computer-interpreted electrocardiography in selecting patients for thrombolytic therapy. MITI Project Investigators

A prehospital computer-interpreted electrocardiogram (ECG) was obtained in 1,189 patients with chest pain of suspected cardiac origin during an ongoing trial of prehospital thrombolytic therapy in acute myocardial infarction. Electrocardiograms were performed by paramedics 1.5 +/- 1.2 h after the onset of symptoms. Of 391 patients with evidence of acute myocardial infarction, 202 (52%) were identified as having ST segment elevation (acute injury) by the computer-interpreted ECG compared with 259 (66%) by an electrocardiographer (p less than 0.001). Of 798 patients with chest pain but no infarction, 785 (98%) were appropriately excluded by computer compared with 757 (95%) by an electrocardiographer (p less than 0.001). The positive predictive value of the computer- and physician-interpreted ECG was, respectively, 94% and 86% and the negative predictive value was 81% and 85%. Prehospital screening of possible candidates for thrombolytic therapy with the aid of a computerized ECG is feasible, highly specific and with further enhancement can speed the care of all patients with acute myocardial infarction.

Dispatcher-assisted telephone CPR: common delays and time standards for delivery

STUDY OBJECTIVES

To determine the rate of bystander CPR before and after implementation of a telephone CPR program in King County; to determine the reasons for dispatcher delays in identifying patients in cardiac arrest in delivering CPR instructions over the telephone; and to suggest time standards for delivery of the telephone CPR message.

DESIGN

An ongoing cardiac arrest surveillance system to calculate the annual bystander CPR rates from 1976 through 1988. Two hundred sixty-seven taped recordings of calls reporting cardiac arrests to nine emergency dispatch centers during 1988 were reviewed and timed.

SETTING

King County, Washington, excluding the city of Seattle.

PARTICIPANTS

Two hundred sixty-seven persons with out-of-hospital cardiac arrests receiving emergency medical services. Arrests in doctors' offices, clinics, or nursing homes were excluded.

INTERVENTIONS

Dispatcher-assisted telephone CPR.

MEASUREMENTS AND MAIN RESULTS

The rate of bystander CPR increased from 32% (1976 through 1981) to 54% (1982 through 1988) after implementation of the dispatcher-assisted telephone CPR program, although an increase in survival could not be demonstrated. The median time for dispatchers to identify the problem was 75 seconds; to deliver the early protocols, 19 seconds; to deliver the ventilation instructions, 25 seconds; and to deliver compression instructions, 30 seconds. The total time to deliver the entire CPR message was 2.3 minutes. The most frequent cause for delay was unnecessary questions (57%) with questions about patient age asked most frequently (32%). Other causes included the caller not being near the patient (29%) and deviations from protocol (22%).

CONCLUSION

In a metropolitan emergency medical services system, a dispatcher-assisted telephone CPR program was associated with an increase in bystander CPR. Delays in proper delivery of telephone CPR can be minimized through training.

Two unusual gait disturbances: astasia abasia and camptocormia

The physiatrist frequently encounters gait abnormalities in his daily practice. Commonly, there is an obvious organic basis for the disturbance. However, on rare occasions, the gait abnormality is the consequence of a functional conversion reaction. This represents both a diagnostic and therapeutic dilemma, in extreme cases leading to unnecessary diagnostic tests and their associated complications and costs. Early suspicion and knowledge of functional gait disorders may expedite the correct diagnosis and the institution of appropriate therapy, shortening hospital stay and eliminating unnecessary procedures. This case study reviews two patients with unique gait disturbances-astasia abasia and camptocormia. Astasia abasia is the inability to stand or walk in the absence of other neurologic abnormalities. Camptocormia is characterized by exaggerated trunk flexion of functional etiology. Both patients demonstrated rapid resolution of symptoms after psychiatric intervention.

Survival rates from out-of-hospital cardiac arrest: recommendations for uniform definitions and data to report

Survival rates for out-of-hospital cardiac arrest vary widely among locations. We surveyed the definitions used in published studies of out-of-hospital cardiac arrest. Data from 74 studies involving 36 communities showed survival rates ranging from 2% to 44%. There were five different case definitions and 11 different definitions of survivors. The absence of uniform definitions prevents meaningful intersystem comparisons, prohibits explorations of hypotheses about effective interventions, and interferes with the efforts of quality assurance. The most satisfactory numerator for a survival rate appears to be survival to hospital discharge; the most appropriate denominator appears to be witnessed adult cardiac arrest of presumed heart disease etiology, with ventricular fibrillation as the initial identified rhythm. Proposed definitions for the data emergency medical services systems should report as they examine their cardiac arrest survival rates are presented.

Synthesis and biological activity of guanylhydrazones of 2- and 4-pyridine and 4-quinoline carboxaldehydes

A series of guanylhydrazones derived from 2- and 4-pyridine and 4-quinoline carboxyaldehydes was synthesized from S-methylisothio-semicarbazide hydroiodide using known procedures. The compounds are analogous to anticancer and antiviral thiosemicarbazones, but several of the guanylhydrazones derived from 4-quinoline carboxaldehyde showed no activity against P388 lymphocytic leukemia in mice. Guanylhydrazones derived from all three heterocyclic aldehydes revealed significant blood pressure lowering effects in the rat, however.

Enantiomers of phenylpropanolamine suppress food intake in hyperphagic rats

Phenylpropanolamine (PPA, d,l-norephedrine), available in many over-the-counter nasal decongestants and appetite suppressants, is a racemic mixture of the enantiomers d- and l-norephedrine. The present study evaluates the effects of the individual PPA enantiomers on a variety of nondrug (food deprivation) and drug-induced hyperphagias (2-deoxyglucose and insulin). Racemic PPA has been shown to significantly suppress food intake in these hyperphagic models. Both l-norephedrine (5-50 mg/kg) and d-norephedrine (5-150 mg/kg), administered intraperitoneally, significantly suppressed feeding after a 4-hr fast during the dark cycle. During the light period, l-norephedrine (7.5, 10, 15 mg/kg) and d-norephedrine (75, 100, 150 mg/kg) significantly reduced food intake at the 1-hr and 3-hr time intervals in the 24-hr food deprivation-, insulin- and 2-deoxyglucose-induced hyperphagic models. Only 7.5 mg/kg l-norephedrine in the insulin-induced hyperphagia at 3 hr failed to significantly suppress feeding. These results indicate that each individual PPA enantiomer possesses the ability to suppress food intake in rats made hyperphagic by various stimuli.

Myocardial Infarction Triage and Intervention Project--phase I: patient characteristics and feasibility of prehospital initiation of thrombolytic therapy

Prehospital initiation of thrombolytic therapy by paramedics, if both feasible and safe, could considerably reduce the time to treatment and possibly decrease the extent of myocardial necrosis in patients with acute coronary thrombosis. Preliminary to a trial of such a treatment strategy, paramedics evaluated the characteristics of 2,472 patients with chest pain of presumed cardiac origin; 677 (27%) had suitable clinical findings consistent with possible acute myocardial infarction and no apparent risk of complication for potential thrombolytic drug treatment. Electrocardiograms (ECGs) of 522 of the 677 patients were transmitted by cellular telephone to a base station physician; 107 (21%) of the tracings showed evidence of ST segment elevation. Of the total 2,472 patients, 453 developed evidence of acute myocardial infarction in the hospital; 163 (36%) of the 453 had met the strict prehospital screening history and examination criteria and 105 (23.9%) showed ST elevation on the ECG and, thus, would have been suitable candidates for prehospital thrombolytic treatment if it had been available. The average time from the onset of chest pain to prehospital diagnosis was 72 +/- 52 min (median 52); this was 73 +/- 44 min (median 62) earlier than the time when thrombolytic treatment was later started in the hospital. Paramedic selection of appropriate patients for potential prehospital initiation of thrombolytic treatment is feasible with use of a directed checklist and cellular-transmitted ECG and saves time. This strategy may reduce the extent and complications of infarction compared with results that can be achieved in a hospital setting.

Cardiac arrest and resuscitation: a tale of 29 cities

Published reports of out-of-hospital cardiac arrest give widely varying results. The variation in survival rates within each type of system is due, in part, to variation in definitions. To determine other reasons for differences in survival rates, we reviewed published studies conducted from 1967 to 1988 on 39 emergency medical services programs from 29 different locations. These programs could be grouped into five types of prehospital systems based on the personnel who deliver CPR, defibrillation, medications, and endotracheal intubation; the five systems were three types of single-response systems (basic emergency medical technician [EMT], EMT-defibrillation [EMT-D], and paramedic) and two double-response systems (EMT/paramedic and EMT-D/paramedic). Reported discharge rates ranged from 2% to 25% for all cardiac rhythms and from 3% to 33% for ventricular fibrillation. The lowest survival rates occurred in single-response systems and the highest rates in double-response systems, although there was considerable variation within each type of system. Hypothetical survival curves suggest that the ability to resuscitate is a function of time, type, and sequence of therapy. Survival appears to be highest in double-response systems because CPR is started early. We speculate that early CPR permits definitive procedures, including defibrillation, medications, and intubation, to be more effective.

Administration of activated charcoal or sodium polystyrene sulfonate (Kayexalate) as gastric decontamination for lithium intoxication: an animal model

To determine whether sodium polystyrene sulfonate (SPS; Kayexalate) is effective in decreasing the absorption of lithium (Li) and to test the assumption that Li is poorly adsorbed by activated charcoal, 130 mice were administered an orogastric dose of LiCl (250 mg/kg) followed immediately by orogastric SPS (10 g/kg, SPS Group), activated charcoal (6.7 g/kg, AC Group), or water in an equivalent volume (Control Group). Subgroups of each of the 3 groups were sacrificed at 1, 2, 4 and 8 hr after treatment and serum analyzed for Li concentration. Statistical analyses revealed no overall difference between the AC Group and the Control Group. However, the SPS Group differed from both the Control and the AC Group at each time interval, with Li concentrations significantly lower in the SPS Group. These results demonstrate that: 1) SPS, in this study, effectively reduced serum Li concentrations in an in vivo model, and 2) activated charcoal did not.

A community survey of the potential use of thrombolytic agents for acute myocardial infarction

We surveyed all patients admitted to nine community hospital coronary care units to determine what proportion could be candidates for thrombolytic therapy. During the 12-month study period, there were 4,115 admissions for possible acute myocardial infarction, and 1,076 (26%) had a discharge diagnosis of myocardial infarction. Patients with myocardial infarction had the following characteristics: 60% had ST elevation seen on the first ECG, 17% had ST depression without ST elevation, 75% were less than 75 years old, 75% had no contraindications to thrombolytic therapy, 78% arrived at hospital within six hours of onset of symptoms, and 94% arrived within 24 hours of symptoms. Criteria for administration of thrombolytic therapy can be grouped as restrictive (arrival within six hours of symptoms and ST elevation) or liberal (arrival within 24 hours of symptoms and ST elevation or ST depression). Applying these characteristics, 26% met restrictive criteria for treatment with thrombolytic therapy, and 36% met liberal criteria. Until liberal criteria (therapy up to 24 hours and ST depression) are convincingly shown to be of benefit, we believe clinicians should apply restrictive criteria to potential candidates for thrombolytic therapy.

Delay between onset of chest pain and seeking medical care: the effect of public education

Thrombolytic therapy for acute myocardial infarction (AMI) is now routinely given in the emergency department and is being considered for pre-hospital care. Its effectiveness is dependent on how early it can be given after the onset of AMI. Maximal benefit, however, is not realized in many patients due to delay in seeking care. The effect of a public media education campaign (message) to shorten patient delay and increase use of emergency medical services (EMS) was evaluated prospectively in King County, Washington. We interviewed 401 patients admitted with possible AMI in the premessage period (4.5 months) and 489 in the postmessage period (4.5 months). The two groups were comparable in all factors except for discharge diagnosis of AMI (premessage, 34%; postmessage, 25%; P less than .01) and history of myocardial infarction or angina (premessage, 52%; postmessage, 43%; P less than .01). The proportion of patients who heard new information on AMI increased significantly in the postmessage period (premessage, 53%; postmessage, 74%; P less than .0001). The campaign, however, did not significantly shorten patient delay in seeking care (median delay: premessage, 2.6 hours; postmessage, 2.3 hours) or alter the distribution of patients in the less-than-two-hour, two-to-four-hour, and more-than-four-hour intervals. The rate of EMS use also was not significantly changed (premessage, 42%; postmessage, 44%). We conclude that a short-duration education campaign may increase AMI knowledge but does not seem to significantly alter patient behavior.

Disagreeable physical characteristics affecting bystander CPR

We determined the frequency of certain disagreeable physical characteristics (presence of vomitus, dentures, blood and/or alcohol on the breath) of a cardiac arrest patient and the effect these characteristics have on a bystander's willingness to perform CPR. Data were collected prospectively on 121 nontraumatic cardiac arrest patients, of whom 35 received bystander-initiated CPR involving a total of 42 bystanders. Seventy-one (59%) patients had one or more disagreeable characteristics identified. Forty (33%) patients vomited; 39 (33%) wore dentures; five (4%) had alcohol on their breath; and nine (7%) had visible blood. Of the 42 bystanders involved, 14 were exposed to one or more of the disagreeable characteristics. No bystander interviewed indicated hesitancy in performing CPR when encountering disagreeable characteristics. Seven bystanders stated they felt inadequately prepared to handle patients who vomited. Because of the high incidence of disagreeable characteristics, notably vomitus, in patients suffering a cardiac arrest, specific training in handling such characteristics seems justified.

Use of the automatic external defibrillator in homes of survivors of out-of-hospital ventricular fibrillation

This 57-month study evaluated the use of automatic external defibrillators (AEDs) in the homes of high risk cardiac patients (survivors of out-of-hospital ventricular fibrillation [VF]). The goal was to determine the utility of these devices by trained lay persons in actual cardiac arrest episodes. Ninety-seven survivors of out-of-hospital VF were enrolled in the study; 59 patients received AEDs, and 38 patients served as a control group. During the study period, 7 deaths occurred in the hospital without preceding out-of-hospital cardiac arrest or from noncardiac causes. There were 14 out-of-hospital cardiac arrests, 10 in the AED group and 4 in the control group. There was 1 long-term survivor in the control group. In the AED group, among the 10 cardiac arrests for which the device was available, it was used in 6. Only 2 patients were in VF; 1 was resuscitated with residual neurologic deficits and survived several months. This study observed a small potential for AEDs to save high risk patients.

Sudden cardiac arrest in Israel: factors associated with successful resuscitation

Out-of-hospital cardiac arrests were studied in Israel from 1984 to 1985. More than 3,500 patients in cardiac arrest received paramedic care. Eighty-three percent of cases were caused by underlying heart disease. Overall, 17% of patients with arrest caused by heart disease were admitted and 7% were discharged from the hospital. There was a wide variation in the percent discharged among the 15 paramedic service areas, ranging from 0% to 13%. Factors associated with successful resuscitation included witnessed collapse, rhythm of ventricular fibrillation, short interval from collapse to cardiopulmonary resuscitation (CPR) and delivery of advanced cardiac life support, collapse at public location, and bystander initiation of CPR. Improvements in survival are likely to result if CPR is more frequently and promptly initiated and the time to arrival of definitive paramedic care can be improved.

A comparison of the effects of phenylpropanolamine, d-amphetamine and d-norpseudoephedrine on open-field locomotion and food intake in the rat

d,l-Norephedrine (PPA) is available as an over-the-counter appetite suppressant and nasal decongestant in the U.S.A. The pseudoisomer d-norpseudoephedrine, is available as an appetite suppressant in Europe, and has been isolated as one of the stimulatory components (cathine) of the Khat plant. Some authors have misidentified cathine as PPA and this confusion in the literature has resulted. PPA and d-norpseudoephedrine possess significantly different pharmacological properties despite having identical structural formulae. Anorectic activity was determined in a food-deprived rat model. PPA and d-norpseudoephedrine were approximately one-tenth as potent as d-amphetamine with all compounds producing a dose-dependent decrease in food intake. Locomotor activity in an open-field apparatus was determined as an index of CNS stimulation. Male Sprague-Dawley rats treated with d-norpseudoephedrine, in doses between 10 and 50 mg/kg, exhibited significantly increased locomotor scores compared to saline (control) treated animals, an increase similar to that caused by 2 mg/kg d-amphetamine. PPA (5-50 mg/kg) failed to increase locomotion significantly. These results indicate that although each compound tested decreased food intake in a dose-dependent fashion, significant differences in open-field locomotion do exist between PPA, d-norpseudoephedrine, and d-amphetamine. Stereoisomeric compounds, although structurally similar, frequently have different pharmacological effects. Thus extreme care must be taken to properly identify these compounds in the literature.

The location of collapse and its effect on survival from cardiac arrest

Survival from cardiac arrest is higher when the collapse occurs outside the home. Of 781 patients collapsing at home, 101 (13%) survived to hospital discharge. This compared with 66 survivors among 248 (27%) patients arresting outside the home (P less than .001). Patients collapsing outside the home were younger and more frequently were men. Cardiac arrests outside the home were more often witnessed, more likely to have bystander CPR, less often preceded by symptoms, and the collapsing rhythm was more frequently ventricular fibrillation. Mean time to CPR was shorter. Multivariate logistic regression showed that the effect of location on survival was still statistically significant, although diminished, after adjusting for the above variables (P less than .01). We speculate that comorbidity, underlying etiology, and activity level may explain the remaining difference. Because 76% of arrests occur in the home, efforts to increase the frequency of bystander-CPR through targeted and dispatcher-assisted CPR programs are warranted.

Lay person use of automatic external defibrillation

The ability of lay persons to learn and retain defibrillation skills using an automatic external defibrillator (AED) was assessed. Thirty-four family members of cardiac arrest survivors were trained in CPR techniques and defibrillation, and evaluated for performance of skills immediately following training and at six-week and three-month follow-ups. All but two were successfully trained to complete three cycles of CPR interspersed with three defibrillatory shocks in an average of four minutes with the first shock delivered in an average of two minutes. Although there were decrements in the speed and quality of performance at each follow-up period (P less than .01), we conclude that most lay persons can learn to operate an AED safely and under simulated conditions provide defibrillatory shocks an average of eight minutes faster than typical response times of emergency medical technicians. These results suggest that AEDs can be placed in many homes of patients at high risk for cardiac arrest.

Automatic external defibrillators used by emergency medical technicians. A controlled clinical trial

In a randomized controlled clinical trial, the effectiveness of emergency medical technician (EMT) use of automatic external defibrillators (AEDs) was compared with EMT use of standard defibrillators for patients in cardiac arrest. A total of 321 cardiac arrest patients were treated during the study: 116 were treated by EMTs using the AED (AUTO group), 158 were treated by EMTs using the standard defibrillators (standard group), and 47 were treated by EMTs using the standard defibrillator when they were assigned to use the AED. There was no significant differences in hospital admission or discharge rates between the AUTO group (54% admitted, 28% discharged) and the standard group (52% admitted, 23% discharged) for patients in ventricular fibrillation (VF), for patients in non-VF rhythms, or for all patients combined. The only significant difference observed was in the time from power ON to first shock: 1.1 minutes average AUTO group and 2.0 minutes average standard group. The treatment groups did not differ significantly in sensitivity for VF (78% AED, 76% standard), specificity for non-VF rhythms (100% AED, 95% standard), or rates of defibrillation to a non-VF rhythm (62% AED, 57% standard). We conclude that in clinical outcomes and device performance, AEDs are comparable with standard defibrillators and should be considered an acceptable alternative. Automatic external defibrillators appear to have advantages over standard defibrillators in training, skill retention, and faster operation. Such devices can make early defibrillation available for a much larger portion of the population. They are a major innovation for the prehospital care of cardiac arrest patients.

Defibrillation performed by the emergency medical technician

As a means of providing defibrillation as soon as possible for those suffering out-of-hospital ventricular fibrillation, numerous communities have trained and authorized emergency medical technicians (EMTs) to provide defibrillatory shocks (EMT-D). The findings of four controlled studies and the experience of various communities have answered important questions. EMT-D programs have been shown effective in urban, suburban, and rural communities with and without paramedic backup. EMT-D programs appear safe, with errors of commission being extremely rare and errors of omission being of acceptably low incidence. Issues still to be resolved include the degree and amount of training that should be given and whether manual or automatic defibrillators should be used. Medical supervision and quality control is the most important aspect of EMT-D programs. At its core, the success of EMT-D programs is confirmation of the principle of early defibrillation. Wider dissemination of early defibrillation will improve survival from sudden cardiac death.