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Biomedical subjects

A Crowther

Publications and source records attributed to A Crowther.

At least 19 recordsLinked to original sources
PubMed2000

Rapid diagnosis of massive pulmonary embolism in a district general hospital.

Effective treatment of massive pulmonary embolism is more likely if diagnostic tests are rapidly available, including during out-of-hours. An agreed protocol was implemented in November 1997, which allowed initiation of thrombolysis by junior doctors within an hour of clinical suspicion of the diagnosis of massive pulmonary embolism in six patients in the subsequent year. A similar approach could be considered by other acute hospitals.

Aged↗
PubMed1999

The effect of orientation on the clarity of Hermann grid illusory lines.

To test the hypothesis that Hermann grid illusory lines are most clear when the grid is presented at a 45 deg, each of 20 participants underwent 10 trials in each of two conditions ('make the lines least clear' and 'make the lines most clear') which were run using a method of adjustment. A matched-pairs t-test applied to the means of the two conditions was significant beyond the 0.01 level. One-group t-tests supported the claim that the illusory lines are least clear for a vertical/horizontal orientation of the grid and most clear when it is rotated 45 deg. The results substantiate, in a systematic manner, 70 years of claims about the effects of grid orientation on illusory line clarity.

Adult↗
PubMed1998

Health needs assessment in primary care: the evolution of a practical public health approach.

The purpose of the paper is to place health needs assessment in its primary care context. This is a dynamic context where changes in policies, staff roles and patient expectations have all to be considered. Given this complexity and the variations between practices, it is necessary to help primary health care teams (PHCTs) to understand their stage of development and how this will directly affect any health needs assessment. The technical and methodological aspects of health needs assessment have been explored and described by others, and that work will not be duplicated here. This paper reviews the health needs assessment (HNA) work of the Ribblesdale Total Purchasing Project (RTPP) and then sets this review against the political, organisational, professional and practical pressures that currently confront primary care. Out of this analysis emerges a diagnostic and development tool which links together, and emphasises the intimate relationships between, five stages of development needed for effective primary care-oriented health needs assessment work. The emphasis is on understanding the place of health needs assessment within the general processes and systems of the primary health care team. The paper concludes by suggesting ways in which public health practitioners and specialists might approach the task of supporting and influencing the evolution of the recently proposed Primary Care Groups and Primary Care Trusts. The overall intention of the article is to stimulate debate and action.

Family Practice↗
PubMed1996

Detection of viable and non-viable cells in connective tissue explants using the fixable fluoroprobes 5-chloromethylfluorescein diacetate and ethidium homodimer-1.

The efficacy of connective tissue explants is difficult to determine, particularly where autopsy material is required for research or clinical applications. We report here an optimised protocol using 5-chloromethylfluorescein diacetate (CMFDA) and ethidium homodimer-1 to distinguish viable and non-viable cells in a range of connective tissue explants. Biopsies and explants of corneae, arteries, cartilage and skin were loaded with fluoroprobes for extended periods (< or = 24h) at low temperatures (4 degrees C), fixed in paraformaldehyde, and processed using a variety of embedding, sectioning, autoradiographic, and immunohistochemical procedures. Detection of fluorescent green CMFDA and red ethidium homodimer was achieved using epi-illuminated light or dual channel confocal microscopy, and clearly differentiated live from dead cells throughout the explants. Furthermore, the intracellular distribution of CMFDA provided superior images of cell shape and morphology not previously available using conventional histochemical techniques. Adaptations of this protocol could prove valuable in a variety of research and clinical applications.

Adolescent↗
PubMed1994

Differences in autonomic nerve function in patients with silent and symptomatic myocardial ischaemia.

BACKGROUND: Autonomic neuropathy provides a mechanism for the absence of symptoms in silent myocardial ischaemia, but characterisation of the type of neuropathy is lacking. AIM: To characterise and compare autonomic nerve function in patients with silent and symptomatic myocardial ischaemia. METHODS AND RESULTS: The Valsalva manoeuvre, heart rate variation (HRV) in response to deep breathing and standing, lower body negative pressure, isometric handgrip, and the cold pressor test were performed by patients with silent (n = 25) and symptomatic (n = 25) ambulatory ischaemia and by controls (n = 21). No difference in parasympathetic efferent function between patients with silent and symptomatic ischaemia was recorded, but both had significantly less HRV in response to standing than the controls (p < 0.005 for silent and p < 0.01 for symptomatic). Patients with silent ischaemia showed an increased propensity for peripheral vasodilatation compared with symptomatic patients (p < 0.02) and controls (p < 0.04). Impaired sympathetic function was found in patients with pure silent ischaemia (n = 4) compared with the remaining patients with silent ischaemia whose pain pathways were presumed to be intact. CONCLUSIONS: Patients with silent ischaemia and pain pathways presumed to be intact have an enhanced peripheral vasodilator response, and if this applied to the coronary vasculature it could provide a mechanism for limiting ischaemia to below the pain threshold. Patients with pure silent ischaemia have evidence of sympathetic autonomic dysfunction.

Autonomic Nervous System↗
PubMed1994

Effects of a patent foramen ovale on arterial saturation during exercise and on cardiovascular responses to deep breathing, Valsalva manoeuvre, and passive tilt: relation to history of decompression illness in divers.

OBJECTIVE: To determine whether the presence of a patent foramen ovale could result in significant arterial desaturation and affect the responses of heart rate and blood pressure to physiological manoeuvres and to determine whether responses differed between those with and those without prior clinical events associated with a patent foramen ovale. DESIGN: Blind controlled study. SETTING: Teaching hospital. PATIENTS: Divers with a large patent foramen ovale shown by contrast echocardiography and divided into those who had neurological decompression illness that started within 30 minutes of surfacing (group 1), those who had no history of decompression illness (group 2), and age and sex matched control divers who had no evidence of intracardiac shunts (group 3). MAIN OUTCOME MEASURES: The change in percentage haemoglobin oxygen saturation during treadmill exercise and the response of heart rate and blood pressure to physiological manoeuvres. RESULTS: There were no significant differences between the three groups but two divers in group 1 showed clinically important desaturation during exercise and unusual blood pressure and heart rate responses to passive tilt. These divers were notable for having the greatest number of episodes and the most severe single episode of spinal cord decompression illness. CONCLUSION: A large patent foramen ovale may be associated with clinically significant arterial desaturation and unusual responses of heart rate and blood pressure in some healthy subjects.

Arteries↗
PubMed1993

Impedance cardiography during exercise in patients with coronary heart disease.

Impedance cardiography may be a simple way of assessing left ventricular performance during exercise. Measurements were therefore made during exercise testing in 102 consecutive male patients with suspected coronary disease prior to cardiac catheterization. These were subsequently divided into four groups: group A, normal; group B, 1- or 2-vessel disease; group C, 3-vessel disease (groups A, B, and C, left ventricular ejection fraction (LVEF) > 55%); and group D, 3-vessel disease with LVEF < 55%. Immediately after peak exercise several impedance measures were significantly correlated with resting LVEF, especially dZ/dtmax (R = 0.41, P < 0.001) and Heather index (R = 0.46, P < 0.001). Heather index was the best discriminator between the disease groups with mean values (95% confidence intervals) of 25.7 (22.2-29.2) (group A), 21.9 (20.6-23.2) (group B), 18.4 (16.2-20.6) (group C), and 15.3 (10.3-20.3) omega s-2 (group D) but there was considerable overlap between groups (risk ratios 1.17 and 3.15 for any and triple-vessel coronary disease respectively). Measurements were therefore of little diagnostic value. The majority of patients with abnormal responses could be identified more simply by their poor exercise tolerance or abnormal blood pressure response.

Adult↗
PubMed1991

Creatine phosphate (Neoton) as an additive to St. Thomas' Hospital cardioplegic solution (Plegisol). Results of a clinical study.

Experimentally, creatine phosphate (CP) added to St. Thomas' Hospital cardioplegic solution (STH) improved post-ischaemic recovery of cardiac function in the rat heart. We investigated the effect of adding CP (10.0 mmol/l) to STH. Fifty open-heart surgery patients were randomized into control (STH) and treated (STH + CP) groups (25 per group). Patients underwent (a) monitoring for peri- and postoperative arrhythmias (48-h Holter monitoring). (b) quantitative birefringence assessment of intraoperative myocardial protection in left and right ventricular biopsies sampled at start of bypass (pre-isch.), end of bypass (end-isch.) and after 10 min reperfusion (post-isch.), and (c) measurement of serum creatine kinase-MB isozyme (CK-MB) values for up to 4 days postoperatively; results were assessed with respect to (d) haemodynamics and postoperative clinical outcome. Inotropic support (adrenaline) was required in three patients (12%) from each group; no patient died. All patients required defibrillation, and the number of direct current shocks required for sinus rhythm was the same in each group. The occurrence and incidence of reperfusion-induced arrhythmias were the same in both groups. Serum CK and CK-MB values were similar throughout the sampling period in both groups of patients; one patient in the control group had raised CK-MB levels postoperatively, but perioperative infarction was not indicated by the electrocardiogram.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Choosing the pacemaker; a rational approach to the use of modern pacemaker technology.

Sophisticated pacemakers now afford greater benefit than only relief of syncope for patients with symptomatic bradyarrhythmia. For clinical reasons it is inappropriate to implant ventricular demand (VVI) pacemakers in every patient, but for both clinical and economic reasons it is also undesirable to use dual-lead or rate-responsive systems indiscriminately. However, the published guidelines for pacemaker choice and investigation are inadequate. We have analysed the clinical assessment and the investigations required in a series of 150 patients with various electrophysiological disorders, considered consecutively for pacemaker implantation using an algorithm to assist decisions. Holter electrocardiography in 77.3%, exercise testing--formal (in 9.3%) or informal (during Holter electrocardiography), electrophysiology study (EPS)--full in 15.3% and partial in 29.3%, and trial of pacing (10.7%) were all used to characterize dysfunction and to define appropriate pacing mode. 142 patients were paced--57.0% with single lead modes (12.7%) AAI, 44.3% VVI) and 43.0% dual-lead (2.8% DVI, 23.9% VDD or VAT, 16.2% DDD). Three patients received rate-responsive systems (VVIR) which, if available, would have been used in nine; four would have been suitable for AAIR and four for dual-lead responsive pacing (DVIR, DDIR or DDDR). We offer a rational approach based on published data for investigation and pacemaker choice in the management of patients with bradyarrhythmia.

Aged↗
PubMed1989

Cold-induced pulmonary oedema in scuba divers and swimmers and subsequent development of hypertension.

The effect of cold and/or a raised partial pressure of oxygen was examined in eleven people with no demonstrable cardiac abnormality but who had pulmonary oedema when scuba diving or surface swimming, and in ten normal divers. These stimuli induced pathological vasoconstriction in the pulmonary oedema group, nine of whom also showed signs of cardiac decompensation when so stimulated. The pulmonary oedema patients have been followed-up for an average of 8 years. Seven have become hypertensive. Except for the onset of lone atrial fibrillation in one normotensive female diver and development of Raynaud's phenomenon in a normotensive man, there have been no cardiovascular events and no deaths.

Acute Disease↗
PubMed1988

Assessment of coronary angioplasty: comparison of visual assessment, hand-held caliper measurement and automated digital quantitation.

Digital subtraction coronary angiograms (DSA) of 27 patients who had undergone coronary angioplasty (PTCA) to a total of 32 lesions were analyzed using an automated border-detecting computer program and hand-held caliper measurement of diameter percent stenosis. The results were compared with visual interpretation of the 35-mm cineangiograms. Visual reports significantly overestimated the pre-PTCA diameter percent stenosis (P less than .001) and underestimated the residual post-PTCA narrowing compared with the automatic computer program (P less than .001). Caliper measurements overestimated significantly the pre-PTCA stenosis in comparison with the computer (P less than .01), but post-PTCA the two methods did not differ significantly (P = .105). There was a positive but poor correlation between caliper and computer measurements (r = .43, P less than .05) performed on the pre-PTCA digital angiograms. Post-PTCA the two methods correlated better (r = 0.78, P less than .001), but further statistical analysis showed important discrepancies between them. The correlation of visual reports and computer measurements was poor pre-PTCA (Kendall's tau = 0.32, P less than .05) and not statistically significant post-PTCA (tau = 0.64, P = .5). We conclude that there is observer bias in the visual reporting of angioplasty results, so that pre-PTCA lesions are overestimated, whereas post-PTCA are underestimated. Hand-held caliper measurement improves the assessment of coronary stenoses in comparison with the visual report but still may not altogether eliminate observer bias; it may overestimate the pre-PTCA stenoses compared with automated border detection.

Analog-Digital Conversion↗
PubMed1988

Magnesium and coronary revascularization.

Twenty patients, who underwent coronary revascularization without cardioplegic arrest, were given (during cardiopulmonary bypass) either magnesium chloride 16 mmol in 10 ml of water (magnesium group) or 10 ml of water alone (control group). Plasma and urinary magnesium concentrations were measured for 24 h after operation. ECG was recorded continuously during this period. QT intervals corrected for heart rate (QTcorr) were calculated from periodic full lead ECG. The mean plasma magnesium concentrations in the control group were less than normal throughout the study, while hypomagnesaemia did not occur in the magnesium group. Urinary magnesium excretion was higher in the magnesium group, with 58% of the administered magnesium excreted in the first 24 h. The observed incidence of frequent or ventricular arrhythmias was 22% in the magnesium group compared with 63% in the control group. No significant differences in QTcorr intervals were observed between the groups.

Arrhythmias, Cardiac↗
PubMed1985

Electrocardiography and echocardiography in patients with chest pain and mitral leaflet prolapse.

34 patients with catheter verified, haemodynamically trivial mitral leaflet prolapse with chest pain and normal coronary arteries were studied. Nineteen had no auscultatory signs of MLP despite clear catheter or echocardiographic evidence of prolapse. Infero-lateral repolarisation changes on the resting electrocardiogram were present in 29%. 50% had false positive exercise tests. M-mode echocardiography proved diagnostically disappointing but sector scans revealed mitral leaflet prolapse in 62%. The apical 4 chamber acoustic window was markedly superior to the parasternal long axis acoustic window.

Adult↗