PubMed Health⌕ Search

Biomedical subjects

R O Cummins

Publications and source records attributed to R O Cummins.

At least 91 records · Page 5Linked to original sources
PubMed1988

A new rhythm library for testing automatic external defibrillators: performance of three devices.

A library of arrhythmias obtained from patients with cardiac arrest was developed. Such a data base will permit both in vitro testing of the rhythm analysis system of automatic external defibrillators before clinical field trials are conducted and comparison of devices. Defibrillators equipped with voice/electrocardiographic tape recorders and used in the prehospital defibrillation programs in Iowa and King County, Washington provided the rhythm source. From these recordings, segments of ventricular fibrillation with minimal artifact and a duration of greater than or equal to 6 s were selected. Segments of ventricular fibrillation (n = 102) were categorized by average peak amplitude as fine (1 to less than 3 mm), medium (3 to less than 7 mm), coarse (7 to less than 12 mm) and extra coarse (greater than or equal to 12 mm), and transcribed onto high fidelity videocassette tapes. Nonventricular fibrillation cardiac arrest rhythms (n = 144), which included wide complex idioventricular rhythms, ventricular and supraventricular tachycardias, asystole and artifact, were also transcribed. Automatic external defibrillators developed by three manufacturers reached a treat (shock) decision on 88 to 93% of the ventricular fibrillation rhythms and on 5 to 10% of the nonventricular fibrillation rhythms. The latter decisions were defined as false positive, though for many rapid nonventricular fibrillation rhythms, countershock may be the appropriate treatment response. There were no statistically significant differences among the three devices in the shock/no shock decisions. A variety of ventricular fibrillation arrhythmias and terminology to express the preclinical performance of automatic external defibrillators are defined. Three commercially available automatic external defibrillators appear to successfully identify ventricular fibrillation and nonventricular fibrillation rhythms.(ABSTRACT TRUNCATED AT 250 WORDS)

Arrhythmias, Cardiac↗
PubMed1988

The frequency of 'occult' ventricular fibrillation masquerading as a flat line in prehospital cardiac arrest.

We investigated the frequency with which a "vector of ventricular fibrillation" may exist in persons in prehospital cardiac arrest. Emergency medical technicians trained in defibrillation were directed to record the rhythm in three different monitor leads whenever they noted an initial flat line. Before these lead switches, the technicians performed a flat line protocol that included inspection of the lead connections to the patient and to the defibrillator, and checks of the calibration and battery status of the devices. They performed this flat line protocol for 127 cardiac arrest patients; 118 were in confirmed asystole after technical problems were corrected. Ventricular fibrillation was detected in only three (2.5%) when the monitor lead was switched. Initial technical problems were more frequent and were identified for ten patients (8%). The frequency of occult ventricular fibrillation (three of 118 asystolic patients) yields a 95% confidence that the true frequency is no greater than 8% to 9%. This suggests that ventricular fibrillation masquerading as asystole is rare. These data do not support protocols for empiric countershocks of patients with an initial flat line on the monitor.

Diagnosis, Differential↗
PubMed1988

An innovative approach to medical control: semiautomatic defibrillators with solid-state memory modules for recording cardiac arrest events.

We evaluated the use of microprocessor-based memory modules incorporated into automatic external defibrillators. These solid-state modules store information about each clinical use, including selected segments of the ECG rhythm and notations on defibrillator operation. A playback unit provides annotated printouts of the recorded information. The purpose of our evaluation was to determine whether this memory module could adequately support medical control "run-reviews" when compared with dualfunction (voice and ECG) tape recordings. A total of 41 resuscitation attempts by emergency medical technicians trained to defibrillate (EMT-Ds) were evaluated in five preselected performance areas: defibrillation skills, command and communication at the scene, patient assessment and support, safety, and speed. When performance was reviewed using the tape recordings, the average EMT-D performance score was 16.2 (maximum, 20); when reviewed using the printouts from the medical control modules, the average score, 7.2, was significantly lower (P less than .01). The lower scores with the medical control module occurred because not all five areas of skill could be evaluated adequately by the memory module approach. Assessment of the areas of communication/command at the scene, patient assessment/support, and safety required verbal tape recordings. The medical control module appeared superior to the tape recordings at providing a quick, convenient, and accurate evaluation of rhythm assessment, shock decisions, time intervals, and defibrillator performance. They make several features of medical control review easier and more convenient, and may encourage implementation of early defibrillation programs. We conclude, however, that medical control modules cannot replace on-scene tape recordings for adequate medical control of EMT-D programs.

Automation↗
PubMed1988

Improved survival from cardiac arrest in the community.

We now know that the elements required to achieve the highest survival rates from out-of-hospital cardiac arrest include: witnessed arrest, rapid telephone notification of the emergency medical service, early initiation of cardiopulmonary resuscitation, rapid arrival within minutes of emergency personnel equipped with a defibrillator, and early advanced airway management and intravenous pharmacology. In the United States, and in several other countries innovative approaches have been tried to bring all these elements together in one system. These approaches include community-wide CPR training programs, telephone-assisted CPR instruction delivered at the time of a cardiac arrest, early defibrillation performed by family members of high risk patients, early defibrillation performed by minimally trained community responders, and early defibrillation performed by minimally trained ambulance personnel. Controlled, prospective studies have demonstrated the effectiveness and practicality of all of these approaches. New studies are in progress with the prehospital use of early transcutaneous cardiac pacing and these show promise. This article reviews the evidence that supports these multi-layered and innovative approaches to the treatment of out-of-hospital cardiac arrest.

Cardiac Pacing, Artificial↗
PubMed1988

Defibrillation.

Defibrillation has emerged as the single most effective intervention for resuscitation of patients from cardiac arrest. This article reviews the electrophysiologic basis of defibrillation, and ways to increase the effectiveness of counter-shocks, particularly for refractory ventricular fibrillation. Automatic implantable and automatic external defibrillators have been developed and are being used in many locations. In future years they will be used increasingly in the homes of high-risk patients, in community settings with limited access to emergency care, and by minimally trained pre-hospital emergency personnel.

Electric Countershock↗
PubMed1987

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.

Analysis of Variance↗
PubMed1987

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.

Adult↗
PubMed1987

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.

Aged↗
PubMed1986

Out-of-hospital cardiac arrest: significance of symptoms in patients collapsing before and after arrival of paramedics.

The authors retrospectively studied victims of sudden cardiac death who experienced cardiac arrest before and after arrival of emergency personnel in order to define possible etiologic factors. There were 265 patients in the arrest-after-arrival (AAA) group and 414 patients in the arrest-before-arrival (ABA) group. All patients in the AAA group had symptoms prior to cardiac arrest. Approximately half the patients in the ABA group had symptoms. The presence or absence of symptoms prior to cardiac arrest appeared strongly associated with the cardiac rhythm at time of collapse and with discharge. Of patients with symptoms, 61% were in ventricular fibrillation or ventricular tachycardia, as compared with 93% of patients without symptoms (P less than 0.001); 32% of patients with symptoms were discharged, as compared with 57% of patients without symptoms (P less than 0.001). These data suggest two potential etiologies for sudden cardiac arrest; thrombosis/ischemia (associated with symptoms) and electrical (associated with no symptoms). Inasmuch as the AAA group represented 14% of witnessed cardiac arrests, patients with symptoms of myocardial ischemia or infarction should be aggressively treated.

Arrhythmias, Cardiac↗
PubMed1986

Home placement of automatic external defibrillators among survivors of ventricular fibrillation.

We performed a study to determine how many patients at highest risk for an episode of ventricular fibrillation (those who have already survived such an event) are potential candidates for automatic external defibrillator placement and accepting of such a device in their homes. All VF survivors in King County, Washington, during 1984 were screened for possible enrollment in the study. Of 95 survivors of out-of-hospital VF, 63 (66%) were eligible and of 47 patients approached, 38 (81%) agreed to participate in the study. These findings suggest that approximately half (product of 66% and 81% acceptance rate equals 53%) of VF survivors potentially could use automatic external defibrillators.

Electric Countershock↗
PubMed1986

Ventilation skills of emergency medical technicians: A teaching challenge for emergency medicine.

We assessed the ability of 64 emergency medical technicians (EMTs) to ventilate a resuscitation manikin with a bag valve mask and with a pocket face mask to determine if their skill levels met the American Heart Association standard of 12 ventilations per minute, each with a tidal volume of 800 mL or more. All ventilation attempts were made during ongoing chest compressions (60 per minute). A successful ventilation was defined as a tidal volume of 800 mL +/- 40 mL. In a preliminary skills assessment, EMTs averaged 4.8 attempts with the bag valve mask and 2.9 attempts with the pocket face mask before a successful ventilation (P less than .01). In a formal skills assessment that lasted two minutes, successful ventilations per minute averaged 8.3 with the bag value mask and 9.9 with the pocket face mask (P less than 0.1). EMTs passed if they averaged ten or more successful ventilations per minute; 67% passed with the bag valve mask and 77% with the pocket face mask (NS). During a ten-minute extended skill assessment the EMTs averaged 9.6 ventilations per minute with the bag valve mask and 9.5 with the pocket face mask (NS). EMTs achieved initial success and maintained continued success better with the pocket face mask, but a reasonably high percentage (67%) met an objective standard when using the bag valve mask. We propose that objective standards be used to test the skills of EMTs for any ventilatory adjunct that they are permitted to use.

Allied Health Personnel↗
PubMed1986

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.

Allied Health Personnel↗