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Biomedical subjects

D A Chamberlain

Publications and source records attributed to D A Chamberlain.

At least 55 records · Page 3Linked to original sources
PubMed1985

Simple mechanical methods for cardioversion: defence of the precordial thump and cough version.

A prospective study was made of the value of the precordial thump and of cough version in life threatening ventricular arrhythmias. Of about 5000 medical and surgical patients, 68 were treated for persistent ventricular tachycardia and 248 for ventricular fibrillation, 86 of whom had presented outside hospital. Mechanical intervention was successful in 26 incidents occurring in 23 patients. Electrocardiographic records were obtained in 14 instances. Ventricular fibrillation was terminated by a thump in five patients and ventricular tachycardia by either a thump or a cough in a total of 17 patients. Four additional instances were recorded of successful recovery from asystolic or unspecified circulatory arrest after a precordial thump. Fifteen patients survived to be discharged from hospital. The potential benefit of the precordial thump and cough versions greatly outweighs their risks; hence these manoeuvres should probably be reintroduced into schedules for first aid resuscitation.

Aged↗
PubMed1984

A community training scheme in cardiopulmonary resuscitation.

Community instruction in basic life support and resuscitation techniques has been offered in Brighton Health District since 1978. Classes are held frequently for the general public and businesses, schools, and other organisations. First aid care for unconscious patients, the treatment of respiratory obstruction or failure, and the recognition and management of cardiac arrest is taught in a single two hour session. Over 20 000 people have been taught, up to 40 at a time in multiple groups of six to eight, by lay instructors usually supervised by ambulancemen trained to "paramedic" standards. Fifty four incidents have been reported to us in which techniques learnt in the classes have been implemented. Five patients recovered after first aid support but subsequently did not seek medical treatment. Of the 34 patients reviewed in hospital, at least 20 survived to be discharged. We believe that intervention may have been life saving in 16 instances. The benefit of cardiopulmonary resuscitation for victims who may have been asystolic is, however, difficult to quantify because the outcome without intervention cannot be predicted accurately. Community training in basic life support should be considered in association with ambulances equipped for resuscitation and hospital intensive care and cardiac care units as an integrated service for the victims of sudden circulatory or respiratory emergencies. The results achieved so far in Brighton and in other more advanced schemes, particularly in the United States of America, may encourage other health authorities to adopt similar programmes.

Adolescent↗
PubMed1984

Automated external defibrillation: laboratory evaluation.

Twelve samples of ventricular fibrillation were fed into nine automated external defibrillator-pacemakers ( AEDP , "Heart Aid") of recent design. All the devices recognised and defibrillated ventricular fibrillation in seven of the samples within 30 sec. None of the devices reacted to two of the samples; in the remaining three there was inter-device variation ranging from an appropriate response to no response, as well as inappropriate pacing or delay in recognition and treatment. Poor recognition of some ventricular fibrillation waveforms with considerable inter-device variation limits the usefulness of this model. A new prototype responded more consistently and future models may be of value in community resuscitation. The difficulty of evaluating the diagnostic capability of AEDP devices in clinical use makes comprehensive laboratory testing essential prior to release.

Electric Countershock↗
PubMed1984

On sudden death.

Explore the source record for details and available documents.

Death, Sudden↗
PubMed1984

Routine and exercise electrocardiography in aircrew; technique, interpretation, and recommendations.

The current CAA requirements for routine electrocardiographic surveillance of flyers is outlined, and the need for care in recording techniques is stressed. Electrocardiographs should meet current standards and be in good repair. Exercise electrocardiograms should not be employed routinely, except possibly for flyers over 50 years of age engaged in single-pilot commercial operations. Exercise tests are of value for individuals with equivocal symptoms or equivocal repolarization changes but the results should be interpreted as far as possible on the basis of probability analysis: to report tests as 'positive' without amplification and with implication of high predictive accuracy is unsatisfactory. The techniques of effort testing should be standardized, should be conducted with scrupulous attention to detail, and should be performed only in centres specified and approved for the evaluation of pilots' fitness to fly.

Adult↗
PubMed1984

Single lead atrial synchronised pacing in patients with cardiogenic shock after acute myocardial infarction.

A pacing system requiring only a single lead was used to establish atrial synchronised pacing in eight patients with complete atrioventricular block and cardiogenic shock following acute myocardial infarction. Spontaneous atrial activity was sensed through electrodes positioned on the pacing lead and used to trigger ventricular demand pacing. A normal atrioventricular relation could be established in each of these critically ill patients without the complexity of inserting and finding a stable position for an additional atrial sensing lead. Atrial synchronised pacing at the spontaneous sinus rate had distinct haemodynamic advantages compared with conventional ventricular pacing at 100 beats/min. Mean cardiac output for the group was 3.3 1/min with atrial synchronised pacing compared with 2.6 1/min with conventional pacing, a significant difference of 27%. Peak systolic pressure averaged respectively 91 and 73 mm Hg in the two pacing modes. With conventional ventricular pacing a pronounced phasic alteration in blood pressure was observed, dependent on the altering relation of the paced beats to spontaneous atrial activity. Atrial synchronised pacing abolished this effect and resulted in a stable blood pressure at or above the peak pressure achieved with conventional pacing. Atrial synchronised pacing with a single lead system can be established rapidly. This mode of pacing has appreciable and significant haemodynamic superiority over conventional ventricular pacing in patients with cardiogenic shock and atrioventricular block following acute myocardial infarction.

Aged↗
PubMed1984

Combined receptor intervention and myocardial infarction.

The aims of treatment in acute myocardial infarction are to limit evolving muscle necrosis, prevent heart failure, maintain electrical stability, and preserve the coronary circulation to avoid progressive or recurrent infarction. No single treatment achieves all these objectives. The rationale for the use of adrenoceptor blocking drugs is that they will oppose the effects of the increased sympathomimetic activity which follows acute infarction and which may adversely affect outcome. More is known of the clinical use of pure beta-blockade than of combined alpha- and beta-blockade with labetalol but in theory combined receptor blockade will produce additional beneficial effects over beta-blockade alone. beta-Adrenoceptor antagonists have a theoretical role in limiting infarct size. They may reduce the oxygen deficit of jeopardised though potentially viable tissue, limiting infarct size by their favourable effect on heart rate, systolic pressure, contractility, and metabolic pathways. That beta-blockade reduces myocardial damage has been confirmed in animal studies. Studies in man using enzyme release or R wave scoring as indicators of infarct size also suggest that oral or intravenous beta-blockers after infarction encourage myocardial salvage. Few studies have been reported in which the effects of combined alpha- and beta-blockade on infarct size have been determined. The actions of a dual blocking agent are more complex and the outcome less predictable than from beta-blockade alone: the advantages of the beta-blocking component will be retained while the alpha-blocking component may conceivably further diminish oxygen demand by reducing systolic pressure and heart size. Less favourably, coronary perfusion pressure may also fall. It is apparent that further clinical studies are needed. Adrenergic blockade may be used to prevent or treat ventricular arrhythmias which develop after infarction in the face of heightened sympathetic tone and continued ischaemia. Clinical and experimental evidence points to the efficacy of beta-blockade in ischaemia-related arrhythmias, but beta-blockade alone is probably ineffective against arrhythmias arising during reperfusion. In experimental studies, alpha-blockers are effective against both forms of arrhythmia although the doses required for reperfusion effects may produce unacceptable hypotension in clinical use. It is possible that combined alpha- and beta-blockade may have broader antiarrhythmic activity than beta-blockers alone but present clinical data on the value of labetalol in controlling postinfarction arrhythmias are sparse.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenergic alpha-Antagonists↗
PubMed1983

Five hundred patients with myocardial infarction monitored within one hour of symptoms.

Of 2886 patients monitored during acute myocardial infarction, 500 were observed within one hour of the onset of symptoms. Half of the early admission group were admitted in response to emergency 999 calls and 435 of them travelled in resuscitation ambulances, where surveillance for arrhythmias was instituted. Pulmonary oedema occurred in 130 patients (26%), cardiogenic shock supervened in 60 (12%), and 115 (23%) died in hospital. Ventricular fibrillation was observed in 98 patients (20%). Forty two of them survived to be discharged, including 20 of the 24 with primary fibrillation which had occurred first in hospital. In only one case did primary ventricular fibrillation occur after the first 10 hours of onset of illness. Sinus bradycardia, atrial fibrillation, ventricular tachycardia, and ventricular fibrillation were all observed more frequently in patients admitted within one hour after the onset of symptoms than in those admitted later. An element of selection is inevitable when early admission is encouraged by the existence of a resuscitation ambulance system; this will depend in part on the early recognition of risk and the geographical location of the attack. These factors may bias the group towards relatively high risk. Nevertheless, prompt admission after myocardial infarction should improve survival by permitting successful management both of ventricular fibrillation and of other arrhythmias which may influence short term and long term prognosis.

Aged↗
PubMed1983

The nuclear stethoscope in the cardiac care unit.

The portable single-crystal scintillation probe (nuclear stethoscope) provides beat-to-beat comparisons of stroke volume and gated measurements of ejection fraction. Comparisons of ejection fractions obtained with the stethoscope and a gamma camera show acceptable correlation except for readings in the very high and very low ranges. The use of the device has been demonstrated by showing changes in ejection fraction obtained with glyceryl trinitrate.

Coronary Disease↗
PubMed1983

The advantages of a coronary care ambulance system.

It is more than a decade since the resuscitation ambulance service in Brighton was established. The value of an integrated resuscitation system in the management of coronary heart disease in the community is reviewed.

Ambulances↗
PubMed1982

Use of an automated external defibrillator-pacemaker by ambulance staff.

A new portable external device detects ventricular fibrillation and profound bradycardia or asystole by analysis of wave forms; it automatically delivers a defibrillating shock or repetitive pacing stimuli. Ambulance crews used the device on 27 cardiac-arrest patients. The initial group (16) was restricted to patients prejudged as probably beyond successful resuscitation, and none survived. The subsequent group (11) was not restricted. 5 were discharged alive from the hospital. The device is simple to use, and its application by modestly trained technicians and lay people may be feasible. Widespread use of the device as an adjunct to conventional cardiopulmonary resuscitation could reduce mortality from out-of-hospital cardiac arrest. The capability for external cardiac pacing enhances the efficacy of treatment.

Ambulances↗
PubMed1982

Comparison of haemodynamic responses to dobutamine and salbutamol in cardiogenic shock after acute myocardial infarction.

Nine patients with critically reduced cardiac output after acute myocardial infarction underwent a single cross-over comparison of dobutamine and salbutamol to compare the haemodynamic effects of these drugs, which have, respectively, predominantly beta 1-adrenergic and beta 2-adrenergic agonist activity. The responses were used to select the more appropriate treatment for individual patients. Only relatively small responses were obtained: those with poorest baseline measurements tended to show the least effect. When the results from the series were averaged, dobutamine (250-750 microgram/min) caused a small but progressive increase in cardiac index (1.8 to 2.2 1/min/m2) throughout the dose range. Systemic blood pressure was not increased, and calculated systemic vascular resistance fell from 25 to 19 units. Heart rate rose from 107 to 118 beats/min and stroke index from 17 to 19 ml/beat/m2. Pulmonary artery end-diastolic pressure fell from 18 to 15 mm Hg. Salbutamol (10-40 microgram/min) produced a similar progressive increase in cardiac index, from 1.6 to 2.21/min/m2. Systemic blood pressure was not altered, and systemic vascular resistance fell from 25 to 20 units. Heart rate rose from 105 to 119 beats/min and stroke index from 16 to 19 ml/beat/m2. Pulmonary artery end-diastolic pressure did not fall. Dobutamine and salbutamol have closely similar haemodynamic effects when used in cardiogenic shock after acute myocardial infarction. Both drugs increase cardiac index but heart rate also rises, and the increase in stroke index is relatively small. Mean arterial pressure is altered little by either agent, but dobutamine (in contrast with dopamine) tends to reduce pulmonary artery end-diastolic pressure, which may be beneficial.

Aged↗
PubMed1982

Role of labetalol in acute myocardial infarction.

1 The role of labetalol in managing acute myocardial infarction is reviewed. 2 After intravenous infusion labetalol lowers blood pressure in patients with increased blood pressure associated with acute myocardial infarction. 3 Although average heart rate was decreased, cardiac index fell only slightly and stroke index was substantially unchanged. 4 In patients whose pretreatment pulmonary artery end-diastolic pressures were increased, labetalol induced decreases, whereas in the presence of normal pressures, these were unchanged. 5 It is concluded that labetalol infusion in patients with acute myocardial infarction is unlikely to precipitate heart failure and is likely to be of value in reducing myocardial oxygen requirement.

Acute Disease↗