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Biomedical subjects

G Walters

Publications and source records attributed to G Walters.

At least 19 recordsLinked to original sources
PubMed1992

Automated external defibrillators: implications for training qualified ambulance staff.

STUDY OBJECTIVE: To investigate the performance of basic trained ambulance personnel using an automated external defibrillator (AED) after a short training program. METHODS: One hundred ninety ambulance attendants working in London received six and one-half hours training in the use of an AED, with written feedback and continuing education regarding performance after training. Performance was assessed over a period of 15 months by analysis of report forms and ECG/audible cassette tapes from the patients who were treated. RESULTS: Staff were able to operate the defibrillator correctly in 96% of cases and followed the protocol sequence taught in 34% of cases. The median time taken to activate the defibrillator following arrival of the ambulance at the scene of cardiac arrest was four minutes (range, one to 13 minutes). In 32% of cases, patients were intubated erroneously or moved to the ambulance before the AED was attached. CONCLUSION: The short course with continuing education was sufficient to train staff in AED operation, but errors in protocol compliance occurred throughout the trial.

Clinical Protocols↗
PubMed1992

Body space measurements in the hyponatraemia of carcinoma of the bronchus: evidence for the chronic 'sick cell' syndrome?

Body space measurements using simultaneous multiple isotope dilution techniques were made in both hyponatraemic and normonatraemic patients with carcinoma of the bronchus and wasting, and compared with those in a group of normal volunteers. Both groups of patients showed osmolal loss from cells. The significance of these findings in relation to the development of hyponatraemia is discussed.

Adult↗
PubMed1992

Studies of acquired sustained hypernatraemia occurring in a diabetic patient.

We describe studies undertaken in a diabetic patient with acquired sustained severe hypernatraemia. Arginine vasopressin levels and thirst scores were grossly subnormal in the presence of marked hypernatraemia but arginine vasopressin increased normally under the influence of negative pressure-induced hypovolaemia. Despite very low levels of arginine vasopressin, polyuria was not a feature suggesting acquired renal hyper-responsiveness. This patient is an additional case of acquired osmoregulatory dysfunction, whose features do not fall neatly into previously described categories.

Arginine Vasopressin↗
PubMed1991

Magnetic resonance imaging of acute symptomatic Schmorl's node formation.

The intraspongious herniation of intervertebral disk material into the endplate of a vertebral body was first described by Schmorl in 1927. Any process which weakens the cartilaginous endplate or the subchondral cancellous bone may predispose to the development of Schmorl's nodes. These include Scheuermann's disease, infection, metabolic disorders, neoplastic disorders, and degenerative disease. In the young individual, however, trauma may precipitate an acute focal and symptomatic endplate herniation by the well-hydrated and delineated nucleus pulposus. Magnetic resonance imaging (MRI) is the most sensitive imaging method for the detection of intervertebral disk disease and, thus, has facilitated the diagnosis of traumatic Schmorl's nodes. MRI was very helpful in diagnosing an acute, traumatic, symptomatic Schmorl's node when plain film radiographs and nuclear medicine bone scan were unremarkable.

Adolescent↗
PubMed1990

Controlled trial of automated external defibrillators in the London ambulance service.

This controlled trial was performed in London and compared outcomes of patients treated by ambulance staff using either basic life support alone or an automated external defibrillator (AED) as an adjunct to basic life support. Five of the 212 (2%) patients were successfully resuscitated by crews using basic life support alone, compared with seven of 186 (4%) patients treated by crews equipped with the AED. Neurological outcomes in the AED group were better. However, meaningful statistical comparisons are not possible with so few survivors. The AED used (Lifepak 200, PhysioControl Corp) was found to be sensitive and specific, and ambulance staff operated the defibrillator correctly. The use of AEDs in an option to maximize the provision of defibrillators in the community and could readily be incorporated into basic ambulance training.

Aged↗
PubMed1989

Urinary excretion of HMMA in children.

In two centres urinary excretion of HMMA was measured in a total of 359 children, aged from birth to 17 years, who were suspected of having a neuroblastoma; the diagnosis was subsequently confirmed in 39. Measurements were made on 24 h urine samples in 246 children, and on random samples in a further 113. The urinary excretion of HMMA relative to creatinine declined progressively with increasing age. After the age of four years the rate of decline was such that some age groups could be combined for statistical analysis. The range of values for each group was similar whether 24 h or random urine collections were used. It is concluded that the latter are adequate for the initial assessment of HMMA excretion.

Adolescent↗
PubMed1987

Hypoglycaemia due to an insulin-receptor antibody in Hodgkin's disease.

Severe fasting hypoglycaemia developed in a patient with Hodgkin's disease after many courses of chemotherapy. Her serum contained a factor which stimulated glucose uptake by rat adipocytes, and this factor was found in the immunoglobulin fraction. The serum also displaced insulin bound to human erythrocytes and both precipitated and phosphorylated insulin receptors extracted from human placenta. The insulin-like substance is probably an antibody to the insulin receptor.

Adipose Tissue↗
PubMed1986

Impaired sodium excretion in response to volume expansion induced by water immersion in insulin-dependent diabetes mellitus.

The renal response to volume expansion produced by water immersion to the neck at 35 degrees C was examined in eight young normotensive uncomplicated insulin-dependent diabetic subjects and in eight matched normal control subjects. Both the diabetic and normal subjects manifested a renal response of natriuresis and kaliuresis on immersion, but the natriuretic response was reduced in the diabetic group. Thus the induced excretion of sodium over the 4 h of immersion was 40 +/- 5 mmol (mean +/- SEM) in the normal group compared with 22 +/- 4 mmol in the diabetic group (P less than 0.02). In the normal subjects creatinine clearance did not change during immersion compared with pre-immersion control values while in the diabetic group it rose from pre-immersion control values of 112 +/- 11 ml/min to a mean value of 127 +/- 11 ml/min during immersion (P less than 0.01). The diabetic subjects thus excreted less sodium despite an increased filtered load during water immersion. Fractional excretion of sodium was significantly reduced in the diabetic subjects compared with the normal control subjects (P less than 0.05). The suppression of plasma renin and aldosterone was similar in normal and diabetic groups. Tubular sodium retention could be an early functional change in the diabetic kidney, and be implicated in the development of diabetic nephropathy.

Aldosterone↗
PubMed1986

Plasma catecholamine levels during water immersion in man.

In ten normal subjects thermoneutral neck-out water immersion produced a highly significant natriuresis and diuresis mediated via an induced central hypervolaemia. During immersion suppression of plasma noradrenaline and adrenaline was observed but no change occurred in plasma dopamine levels. No correlation was found between the suppression of noradrenaline and the diuresis and natriuresis. The reduction in plasma noradrenaline observed may reflect a widespread diminution of sympatho-adrenal activity during water immersion. This reduction could be a consequence of the cardiovascular changes of immersion and may not be directly involved in the mechanism of the renal response.

Adult↗
PubMed1986

Arginine infusion blocks the action of parathyroid hormone but not arginine vasopressin on the renal tubule in man.

Six male volunteers were infused with arginine (0.5 g/kg body weight) over 30 min, after an overnight fast and water deprivation. There was a significant decrease in renal phosphate clearance (P less than 0.025) and urinary cyclic adenosine monophosphate (cAMP) output (P less than 0.025) during the 60- to 90-min period after the beginning of the infusion; both returned to the preinfusion basal levels within 150 min. The plasma levels of parathyroid hormone (PTH) were not affected by the infusion and remained unchanged during the subsequent 150 min. Plasma levels of arginine vasopressin (AVP) were also not significantly affected although plasma osmolality increased by 6-9 mmol/kg in all subjects. The infusion resulted in a diuresis, and a fall in urine osmolality but a decrease in free-water clearance; creatinine clearance was not affected. Six other subjects were given a bolus of 230 i.u. PTH intravenously, and 20 days later this was repeated during an infusion of arginine (0.5 g/kg body weight). There was a significant decrease in urinary phosphate (P less than 0.025) and cAMP excretion (P less than 0.05) when PTH was given with arginine. It is suggested that arginine blocks the action of PTH on the proximal renal tubule but not that of vasopressin on the distal nephron and collecting ducts.

Arginine↗
PubMed1986

Sodium retention in response to saline infusion in uncomplicated diabetes mellitus.

The response to a 21 infusion of physiological saline infusion was studied in 7 male uncomplicated insulin-dependent diabetics and in 7 non-diabetic male controls. The urinary sodium excretion in the diabetics in each of the 4 hr following the infusion was approximately half that of the controls. The total induced sodium excretion in controls was 34 +/- 4 mmols (mean +/- SEM) but only 14 +/- 4 mmols in the diabetics (p less than 0.005). The hourly creatinine clearance rate was higher in diabetics than in controls indicating a mechanism of reduced sodium excretion via enhanced tubular reabsorption rather than impaired filtration. This propensity to sodium retention in diabetics may play a role in the tendency to cardiovascular and renal complications.

Blood Glucose↗
PubMed1985

Abrupt withdrawal of atenolol in patients with severe angina. Comparison with the effects of treatment.

The effects of abrupt withdrawal of atenolol, a long acting cardioselective beta blocker, were studied in 20 patients with severe stable angina pectoris admitted to hospital for coronary arteriography. During the 144 hour postwithdrawal period no serious coronary events occurred. Mean and maximal daily heart rates rose steadily for at least 120 hours. No important arrhythmias were noted on ambulatory electrocardiographic monitoring. Treadmill exercise testing at 120 hours showed little reduction in the times to angina, ST depression, and maximal exercise when compared with those recorded at 24 hours. This deterioration was small when contrasted with the improvements in these indices produced by atenolol treatment in a similar group of patients not admitted to hospital. No change in catecholamine concentrations or acceleration of the heart rate response to exercise occurred after atenolol withdrawal, suggesting that rebound adrenergic stimulation or hypersensitivity was absent or insignificant. Catastrophic coronary events after beta blockade withdrawal (the beta blockade withdrawal syndrome) have occurred almost exclusively in patients taking propranolol, many of whom had unstable angina at the time of withdrawal. This study showed that in patients with stable angina, even when severe, the abrupt withdrawal of atenolol can be expected to result in only minor clinical consequences. The risk to any patient of so called rebound events after withdrawal of beta blockade seems to be related to both the clinical setting and the agent being used.

Adult↗