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Biomedical subjects

J Rawles

Publications and source records attributed to J Rawles.

At least 19 recordsLinked to original sources
PubMed1999

Latitude-related changes in the amplitude of annual mortality rhythm. The biological equator in man.

There is extensive literature describing the effect of season on mortality rates, especially in cardiovascular and respiratory disease. This study compares latitude with the extent of seasonal variation of monthly deaths from all causes. In developed countries, there is a peak of deaths in winter and a trough in summer. Monthly numbers of deaths were established in 89 countries in the Northern and Southern Hemisphere. Using cosinor analysis, the extent of seasonal variation (amplitude) was established and correlated with latitude. The amplitude of seasonality was greatest in mid-latitude around 35 degrees, but low or absent near the equator and subpolar regions. The amplitude can differ at the same latitude. The weather in equatorial regions and in habitations near the Arctic Circle is very different, but death has a similar seasonal rhythm. The purpose is to record this epidemiological finding even though no simple explanation is provided. Weather alone cannot explain it, and it is possible that day length (photoperiod) has an important, but complex, underlying role.

Biometry↗
PubMed1998

Call to needle times after acute myocardial infarction in urban and rural areas in northeast Scotland: prospective observational study.

OBJECTIVE: To determine call to needle times and consider how best to provide timely thrombolytic treatment for patients with acute myocardial infarction. DESIGN: Prospective observational study. SETTING: City, suburban, and country practices referring patients to a single district general hospital in northeast Scotland. SUBJECTS: 1046 patients with suspected acute myocardial infarction given thrombolytic treatment. MAIN OUTCOME MEASURES: Time from patients' calls for medical help until receipt of opiate or thrombolytic treatment, measured against a call to needle time of 90 minutes or less, as proposed by the British Heart Foundation. RESULTS: General practitioners were the first medical contact in 97% (528/544) of calls by country patients and 68% (340/502) of city and suburban patients. When opiate was given by general practitioners, median call to opiate time was about 30 minutes (95% within 90 minutes) in city, suburbs, and country; call to opiate delay was about 60 minutes in city and suburban patients calling "999" for an ambulance. One third of country patients received thrombolytic treatment from their general practitioners with a median call to thrombolysis time of 45 minutes (93% within 90 minutes); this compares with 150 minutes (5% within 90 minutes) when this treatment was deferred until after hospital admission. In the city and suburbs, no thrombolytic treatment was given outside hospital, and only a minority of patients received it within 90 minutes of calling; median call to thrombolysis time was 95 (46% within 90 minutes) minutes. CONCLUSIONS: The first medical contact after acute myocardial infarction is most commonly with a general practitioner. This contact provides the optimum opportunity to give thrombolytic treatment within the British Heart Foundation's guideline.

Acute Disease↗
PubMed1998

Non-invasive assessment of cardiac output in children.

BACKGROUND: Stroke distance, the systolic velocity integral of aortic blood flow, is a linear analogue of stroke volume; its product with heart rate is minute distance, analogous to cardiac output. OBJECTIVE: To investigate the feasibility of assessing cardiac output in children with a simple non-invasive Doppler ultrasound technique, and to determine the normal range of values. METHODS: Peak aortic blood velocity, stroke distance, and minute distance were measured through the suprasternal window in 166 children (mean age 9.6 years, range 2-14) using a portable non-imaging Doppler ultrasound instrument. RESULTS: The technique was well tolerated by all the children participating. Mean peak aortic blood velocity was 138 cm/s and was independent of age. Mean stroke distance was 31.8 cm and showed a small but significant increase with age; mean minute distance was 2490 cm and fell with age, as did heart rate. CONCLUSIONS: Suprasternal Doppler ultrasound measurement of stroke distance is a convenient, well tolerated, non-invasive technique for the assessment of cardiac output in children. The normal range of values during childhood has been established. The technique has great potential for assessing hypovolaemia in children.

Adolescent↗
PubMed1998

Audit of prehospital thrombolysis by general practitioners in peripheral practices in Grampian.

BACKGROUND: In the Grampian region early anistreplase trial (GREAT), domiciliary thrombolysis by general practitioners was associated with a halving of one year mortality compared with hospital administration. However, after completion of the trial and publication of the results, the use of this treatment by general practitioners declined sharply. OBJECTIVE: To increase the proportion of eligible patients receiving timely thrombolytic treatment from their general practitioners. SETTING: Practices in Grampian located > or = 30 minutes' travelling time from Aberdeen Royal Infirmary, where patients with suspected acute myocardial infarction were referred after being seen by general practitioners. AUDIT STANDARD: A call-to-needle time of 90 minutes, as proposed by the British Heart Foundation (BHF). METHODS: Findings of this audit of pre-hospital management of acute myocardial infarction were periodically fed back to the participating doctors, when practice case reviews were also conducted. RESULTS: Of 414 administrations of thrombolytic treatment, 146 (35%) were given by general practitioners and 268 (65%) were deferred until after hospital admission. Median call-to-needle times were 45 (94% < or = 90) and 145 (7% < or = 90) minutes, respectively. Survival at one year was improved with prehospital compared with hospital thrombolysis (83% v 73%; p < 0.05). The proportion of patients receiving thrombolytic treatment from their general practitioners did not increase during the audit. CONCLUSIONS: In practices > or = 30 minutes from hospital, the BHF audit standard was readily achieved if general practitioners gave thrombolytic treatment, but not otherwise. Knowledge of the benefits of early thrombolysis, and feedback of audit results, did not lead to increased prehospital thrombolytic use. Additional incentives are required if general practitioners are to give thrombolytic treatment.

Aged↗
PubMed1997

An economic evaluation of thrombolysis in a remote rural community.

OBJECTIVES: To assess the cost effectiveness of community thrombolysis relative to hospital thrombolysis by investigating the extra costs and benefits of a policy of community thrombolysis, then establishing the extra cost per life saved by community thrombolysis. DESIGN: Economic evaluation based on the results of the Grampian region early anistreplase trial. SETTING: 29 rural general practices and one secondary care provider in Grampian, Scotland. SUBJECTS: 311 patients recruited to the Grampian region early anistreplase trial. INTERVENTIONS: Intravenous anistreplase given either by general practitioners or secondary care clinicians. MAIN OUTCOME MEASURES: Survival at 4 years and costs of administration of thrombolysis. RESULTS: Relative to hospital thrombolysis, community thrombolysis gives an additional probability of survival at 4 years of 11% (95% confidence interval 1% to 22%) at an additional cost of 425 pounds per patient. This gives a marginal cost of life saved at 4 years of 3,890 pounds (1,990 pounds to 42,820 pounds). CONCLUSIONS: The cost per life saved by community thrombolysis is modest compared with, for example, the cost of changing the thrombolytic drug used in hospital from streptokinase to alteplase.

Anistreplase↗
PubMed1996

Magnitude of benefit from earlier thrombolytic treatment in acute myocardial infarction: new evidence from Grampian region early anistreplase trial (GREAT)

OBJECTIVE: To generalise from the results of the Grampian region early anistreplase trial (GREAT) and to express the benefit of earlier thrombolysis in terms of lives saved per hour of earlier treatment. DESIGN: Multivariate analysis of a randomised double blind trial. SETTING: 29 rural practices in Grampian region and teaching hospitals in Aberdeen. SUBJECTS: 311 patients with suspected acute myocardial infarction and without contraindications to thrombolysis who were seen by their general practitioners within four hours of the start of symptoms. INTERVENTIONS: Anisterplase 30 units given intravenously, either by general practitioners before hospitalisation or later in hospital. MAIN OUTCOME MEASURE: Death within 30 months of entry into trial. RESULTS: Death within 30 months was positively related to age (P < 0.0001) and to delay between start of symptoms and thrombolytic treatment (P = 0.0004). However, the probability of dying rose exponentially with earlier presentation, so death within 30 months was negatively related to the logarithm of the time of randomisation (P = 0.0163). In patients presenting two hours after start of symptoms each hour's delay in receiving thrombolysis led to the loss of 21 lives per 1000 within 30 days (95% confidence interval 1 to 94 lives per 1000) (P = 0.03) and 69 lives per 1000 within 30 months (16 to 141 lives per 1000) (P = 0.0004). CONCLUSIONS: The magnitude of the benefit from earlier thrombolysis is such that giving thrombolytic treatment to patients with acute myocardial infarction should be accorded the same degree of urgency as the treatment of cardiac arrest.

Anistreplase↗
PubMed1996

An investigation of the changes in aortic diameter and an evaluation of their effect on Doppler measurement of cardiac output in pregnancy.

Measurement of cardiac output by means of Doppler ultrasound is based on the velocity of aortic blood flow and therefore requires that aortic diameter should not change between measurements. Work has been published which suggests that, in pregnancy, aortic diameter varies significantly with systemic blood pressure. The implication of this is that aortic diameter must be remeasured for each determination of cardiac output in pregnant patients. This study investigated the changes in aortic diameter with blood pressure in patients having spinal anaesthesia for caesarean section. Aortic diameter did appear to vary with blood pressure but this variation was within the error of the measurement and did not significantly affect the accuracy of the technique.

Journal Article↗
PubMed1995

Impact of resuscitation and thrombolysis on mortality rate from acute myocardial infarction.

Our objective was to estimate the saving of life by thrombolysis and resuscitation in acute myocardial infarction (AMI) before and after hospital admission. We studied all 1516 patients admitted to a Scottish teaching hospital in 1990 and 1992 who had a final diagnosis of AMI, and 311 patients enrolled in the Grampian region early anistreplase trial (GREAT). Cardiac arrest occurred in 250/1516 (16%) hospital patients. Of these, 77 (31%) were discharged alive--a saving of 51 lives per thousand cases. 797 (53%) patients received thrombolysis, of whom 114 (14%) died. Assuming the same relative reduction in mortality as in the second international study of infarct survival (ISIS-2; 23%), 34 lives were saved by thrombolytic therapy, representing 22 lives per thousand cases. Of 311 patients in GREAT, 15 (5%) had prehospital cardiac arrest, with 7 patients surviving to discharge (48%)--a saving of 23 lives per thousand cases. Those patients given domiciliary thrombolysis had a one month mortality of 6.7% (11/163) compared with 12.2% (18/148) for those receiving hospital thrombolysis--a saving of 55 lives per thousand cases for prehospital thrombolysis. This is additional to 28 lives per thousand estimated for thrombolytic therapy in hospital, totalling 83 lives saved per thousand cases of AMI receiving thrombolytic therapy prehospital. In hospital, more lives were saved by resuscitation than by thrombolytic therapy, but this ratio was reversed in the period before hospital admission. These results emphasise the paramount importance of resuscitation in hospital, and the enhanced efficacy of thrombolysis when given at the earliest opportunity.

Aged↗
PubMed1995

The risks of thrombolysis in patients without acute myocardial infarction.

The risk of administering thrombolysis to patients with suspected myocardial infarction who subsequently do not sustain an infarct, but develop complications associated with thrombolysis is of concern to all physicians. The objective of this study was to ascertain the effect of altering the criteria for the administration of thrombolysis on the number of patients who received thrombolysis in the absence of infarction. During 1990 and 1992 details of all admissions with chest pain were recorded. During 1991 the policy for the administration of thrombolysis was altered so that only patients with ST elevation were eligible. A total of 1473 patients were admitted with chest pain in 1990 and 1967 in 1992. Of the patients admitted in 1990, 663 (45%) had confirmed infarction of whom 378 (57.0%) received thrombolysis. In 1992, 855 (43%) were admitted with infarction and of these 450 (52.6%) had thrombolytic therapy. 118 patients had no evidence of myocardial infarction, but received thrombolysis. 91 (77.1%) were admitted in 1990 and 27 (22.9%) in 1992 (P < 0.01). Of these only 24 (20%) subjects had ST elevation or bundle branch block on the admission electrocardiograph and 41 (35%) had normal tracings. Four (3%) subjects had serious complications of whom one (0.8%) died. The implementation of ECG criteria resulted in a significant reduction in the number of patients without infarction who received thrombolysis, but did not significantly alter the rate of thrombolysis in those with definite myocardial infarction.

Arrhythmias, Cardiac↗
PubMed1995

Guidelines for general practitioners administering thrombolytics.

Acute myocardial infarction (AMI) recognises no boundaries, and the patient's greatest need occurs at the interface between primary care and hospital system. Ideally, the general practitioner, if summoned, should be able to provide resuscitation, analgesia with opiates, and thrombolytic therapy. Thrombolytics should certainly be given to eligible patients by the general practitioner if an hour could be saved by so doing. Optimising the risk-benefit ratio for thrombolytic therapy given in the community is a challenge to clinical judgement. Experience with this potent treatment is best obtained under a degree of supervision, which could take the form of an audit of the prehospital management of suspected AMI. With prehospital administration of thrombolytic therapy at the first opportunity, the chances of saving a life are better than 1 in 10, while the excess risk of a disabling stroke is about 1 in 1000.

Family Practice↗