PubMed Health⌕ Search

Biomedical subjects

A Crowther

Publications and source records attributed to A Crowther.

36 records · Page 2Linked to original sources
PubMed1984

Cardiac arrhythmias during anaesthesia for laparoscopy.

Fifty-six patients undergoing elective laparoscopy were allocated randomly to two groups. Group H received alcuronium and were ventilated artificially using 0.5% halothane and nitrous oxide in oxygen. Group E breathed spontaneously a mixture of enflurane and nitrous oxide in oxygen. Arterial pressure, heart rate, tidal volume, respiratory rate and end-tidal carbon dioxide tension (PECO2) were monitored. The electrocardiogram (ECG) was recorded continuously using magnetic tape, from before induction until the patient left the recovery area. The incidence of arrhythmias was similar in the two groups. No arrhythmias occurred after the insufflated carbon dioxide had been removed from the abdomen. Spontaneous ventilation with enflurane anaesthesia is a simple and safe, technique for routine laparoscopy, providing the intra-abdominal pressure does not exceed 25 mm Hg.

Adolescent↗
PubMed1984

Cellular sodium concentration and vasoconstrictor state in hypertension.

The sodium content of peripheral blood leucocytes was estimated in two separate investigations of the relationship between cellular sodium content and the vasoconstrictor state. In the first study various parameters of forearm blood flow were measured in a group of 31 normal subjects. A positive correlation was found between peripheral vascular resistance and leucocyte sodium content (p less than 0.05), and a negative correlation between venous compliance (VV60) and leucocyte sodium content (p less than 0.001). In the second study the leucocyte sodium content of 14 patients with essential hypertension was investigated before and after treatment with the calcium antagonist verapamil. The sodium content was found to be abnormally high, as previously described, and treatment with verapamil was found to reverse the defect. Both studies indicate a link between cell sodium content and the vasoconstrictor state, and the results are discussed in light of current theory.

Adult↗
PubMed1983

Cardiac arrhythmias during outpatient dental anaesthesia: comparison of halothane with enflurane.

In 75 young female patients undergoing extraction of 3rd molar teeth during halothane or enflurane anaesthesia, the electrocardiogram was recorded on magnetic tape and analysed subsequently for arrhythmias, using a high-speed analyser. Enflurane induced a much lower frequency of arrhythmia during surgery than halothane, but there was otherwise little difference between the two drugs in the quality of anaesthesia or recovery. Many arrhythmias occurred before exposure of the patient to enflurane or halothane; the significance of this is discussed.

Adolescent↗
PubMed1983

The effects of oral digoxin therapy in primary mitral leaflet prolapse.

The effects of oral digoxin on symptoms, arrhythmias, exercise tolerance and echocardiographic function in primary mitral leaflet prolapse were studied in 23 patients using a double-blind crossover protocol. Digoxin reduced the incidence and severity of chest pain compared with both the control (P = 0.0002) and placebo (P = 0.0005) periods. We found a high (83%) incidence of predominantly minor arrhythmias on continuous ambulatory monitoring. Digoxin favourably affected the incidence of frequent supraventricular ectopic beats and supraventricular tachycardia but was associated with a significant number (P less than 0.0025) of asymptomatic bradyarrhythmias. In patients with frequent ventricular ectopics, digoxin had no consistent effect. No difference in exercise tolerance between treatment periods was found on maximal treadmill stress testing, but digoxin administration resulted in an increase in echocardiographic mean circumferential fibre shortening velocity (P less than 0.01) and fractional shortening percent (P less than 0.01). This study demonstrates the efficacy of oral digoxin therapy in ameliorating chest pain in patients with primary mitral leaflet prolapse and suggests a favourable effect on supraventricular arrhythmias in such patients.

Administration, Oral↗
PubMed1982

The effect of hyperacetatemia on cardiac output during regular hemodialysis.

We used impedance cardiography to monitor changes in cardiac output in 22 adult patients with terminal renal failure during hemodialysis against a dialyzate containing acetate. In 7 patients arterial acetate levels rose progressively during dialysis while in the remainder they remained low and steady. Patients who developed hyperacetatemia were able to maintain an elevated cardiac output during dialysis in contrast to the patients with stable acetate levels in whom cardiac output fell. These results strengthen our previous conclusion that acetate as used in conventional regular hemodialysis does not have a cardiodepressant action. The reported benefits of bicarbonate dialysis therefore involve other factors.

Acetates↗
PubMed1981

The effects of chronic oral cimetidine therapy on the cardiovascular system in man.

1 The demonstration of histamine (H2) receptors in the cardiovascular system in man and the widespread use of the specific H2 receptor antagonist cimetidine for the treatment of peptic ulcer has necessitated assessment of the cardiovascular effects of this drug during oral therapy in man. 2 Consequently, nineteen patients with a history of peptic ulcer but in symptomatic remission underwent a double-blind crossover trial of oral cimetidine v placebo, each treatment period lasting 4 weeks. No significant difference in various cardiac parameters at rest (heart rate, blood pressure, ECG) or following a maximal treadmill exercise test (time-into-protocol, maximum heart rate and blood pressure) was found between the groups. Similarly, cimetidine produced no change in the incidence of ventricular ectopics or in heart rate on 24 h ambulatory monitoring and had no effect on left ventricular volume or contractility as measured by echocardiography. 3 Thus oral administration of cimetidine in a dose of 400 mg four times daily was associated with no demonstrable cardiovascular changes. In addition, since this dose is thought compatible with cardiovascular H2 receptor blockade this study favours the lack of a physiological role for these receptors in man.

Cardiovascular Diseases↗
PubMed1980

Assessment of prognostic factors in patients undergoing surgery for non-rheumatic mitral regurgitation.

Twenty-four patients who had undegone mitral valve surgery for pure non-rheumatic mitral regurgitation were studied non-invasively six months to six years postoperatively. The long-term results of operation were assessed on the basis of clinical history, echocardiography, and treadmill stress testing using a points scoring system. The score so obtained was used to divide the patients into those with a good response to surgery (group 1) and those responding poorly (group 2). The effects on the long-term surgical outcome of several intraoperative and preoperative factors were then analysed both together and separately. A short symptomatic history (less than 1 year), a normal left ventricular end-diastolic volume index (less than or equal to 100 ml per m2), and a large post-ectopic potentiation of KV max (greater than 50 s-1) were found to be favourable prognostic factors when analysed independently. An angiographic ejection fraction less than 0.5 was uniformly associated with a poor outcome, and 71 per cent of patients in atrial fibrillation at the time of operation also responded badly. In those patients with good long-term function, cold potassium cardioplegia was more commonly used than intermittent aortic cross clamping as the means of intraoperative myocardial preservation, though this difference did not reach conventional significance. A standard analysis of variance allowed assessment of length of history, left ventricular end-diastolic volume index, and type of valve prosthesis simultaneously. This indicated that both length of history and left ventricular end-diastolic volume index were highly significant prognostic factors. The use of a Björk-Shiley as opposed to a Starr-Edwards prosthesis also emerged as significantly favouring a good long-term result. The state of the left ventricular myocardium before operation and the type of valve prosthesis used were thus shown to be the prime determinants of surgical outcome in these patients. The optimum time for operation was shown to be within one year of the onset of symptoms, and before the left left ventricular end-diastolic volume index exceeds 100 ml per m2, or the ejection fraction falls to less than 0.5. At such a time, irreversible changes in myocardial function sufficient to negate the beneficial effects of mitral valve surgery have not yet occurred.

Angiocardiography↗
PubMed1980

Controlled study of 24-hour ambulatory electrocardiographic monitoring in patients with transient neurological symptoms.

Sixty unselected patients with transient neurological symptoms underwent 24-hour ambulatory electrocardiographic (ECG) monitoring. Haemodynamically significant arrhythmias were observed in 32% of patients, but in only 3% of an age- and sex-matched control group. Nine patients received specific anti-arrhythmic therapy, which resulted in marked symptomatic improvement in each case. It is argued that 24-hour ECG monitoring is a valuable diagnostic tool in the investigation of transient neurological symptoms.

Adolescent↗
PubMed1979

A computerised dichromatic earpiece densitometer for the measurement of cardiac output.

This study assesses a precalibrated dichromatic earpiece densitometer and microprocessor for the measurement of cardiac output by indocyanine green dye dilution. The measured cardiac output is compared with values of cardiac output simultaneously determined using a cuvette densitometer. The microprocessor computation of cardiac output agreed very closely with the cardiac output determined by manual calculation from the same dye dilution curves (standard deviation +/- 1.47%). The reproducibility of the earpiece densitometer (standard deviation +/- 5.2%) was virtually identical to that of the cuvette densitometer (+/- 5.3%). In a comparison of earpiece and cuvette densitometers for 60 measurements of cardiac output following pulmonary arterial injection of dye and for 50 measurements following femoral venous injection of dye, correlation coefficients were 0.83 and 0.78 and the standard deviations of the differences of simultaneous measurements were 7.2% and 8.3% respectively. The instrument offers an accurate reproducible and relatively noninvasive technique for measuring cardiac output.

Cardiac Output↗
PubMed1979

Echocardiographic and exercise evaluation of results of mitral valvotomy operations.

M-mode echocardiography was performed in 54 patients 1 month to 3 years after mitral valvotomy for dominant mitral stenosis. The mitral valve closure index (MVCI), an index previously shown to correlate well with the calculated mitral valve area, was used to diagnose residual mitral stenosis. Using the equation MVCI = 33 MVC--12, 12 patients (22%) were deemed to have mild, 4 (7%) moderate, and 2 (4%) severe residual stenosis. Repeat cardiac catheterisation confirmed the diagnosis in 7 patients. The postoperative mitral valve closure index correlated significantly with patients' subjective symptoms and objective exercise indices. It was higher in patients in whom the posterior mitral leaflet movement became normal after valvotomy, and was lower in patients in whom the anterior mitral leaflet excursions below 14 mm before operation. The mitral valve closure index is a sensitive index for diagnosing residual mitral stenosis after valvotomy.

Adolescent↗
PubMed1979

Thallium-201 myocardial imaging in assessment of results of aortocoronary bypass surgery.

Thirty-six patients were assessed by thallium-201 myocardial imaging before and after aortocoronary bypass operations and the results were compared with evaluation based on symptomatic assessment, exercise testing, and electrocardiography. After operation, the majority of patients were free from symptoms or symptomatically improved with increased exercise duration. Perioperative myocardial damage was shown in eight patients and myocardial ischaemia in 15 patients when assessed by thallium imaging during exercise. Thallium imaging proved more sensitive than electrocardiography in the demonstration of perioperative infarction and in the detection of postoperative ischaemia. Exercise electrocardiography may be misleading after aortocoronary bypass operations. Thallium imaging offers a simple, objective evaluation of the results of revascularisation procedures, throws light on the mechanisms of relief of angina by operation, and helps in the assessment of the patient whose progress is unsatisfactory after operation.

Adult↗
PubMed1978

The effect of propranolol on thyroid hormones and oxygen consumption in thyrotoxicosis.

The possibility that propranolol may exert its beneficial actions in thyrotoxicosis by an effect on thyroid hormone concentrations has been investigated by measuring these and oxygen consumption in a group of thyrotoxic patients before and after treatment with propranolol. Following treatment a significant fall in plasma T3 concentration and oxygen consumption occurred and a direct correlation was found between these two variables. Propranolol may, therefore, exert some of its beneficial effects in thyrotoxicosis by an action on T3 metabolism.

Adult↗
PubMed1976

Three-day and ten-day chemotherapy for urinary tract infections in general practice.

The length of a course of antibiotic treatment for urinary tract infection varies with the habits of the prescriber. Many patients do not complete a course of treatment once their symptoms have subsided. In uncomplicated urinary tract infection among women seen in general practice a three-day course of amoxycillin was as effective as a 10-day course of the same drug in the same dose. Relief of symptoms was equal in both groups and bacteriuria was eliminated equally successfully in both regimens. There was no significant difference between the two groups in the incidence of side effects from the drugs. The financial saving which could accrue from adopting this therapeutic regimen would be significant.

Amoxicillin↗
PubMed1975

Letter: SI units.

Explore the source record for details and available documents.

Group Practice↗