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Biomedical subjects

D F Treacher

Publications and source records attributed to D F Treacher.

47 records · Page 3Linked to original sources
PubMed1992

Delivery of a nebulized aerosol to a lung model during mechanical ventilation. Effect of ventilator settings and nebulizer type, position, and volume of fill.

Several factors may affect the delivery of a nebulized aerosol to the lung through an endotracheal tube during mechanical ventilation. To study these factors in vitro, a model representing ventilation of an adult patient was constructed by linking a Servo 900C ventilator to a standard humidified circuit and an endotracheal (ET) tube positioned within a pipe representing the trachea. This was connected via a filter to a lung simulator. Nebulizers filled with 99mTc human serum albumin were positioned in the circuit, and the delivery of nebulized aerosol through the ET tube into the filter was measured using a gamma camera. With the use of an inspiratory phase-activated System 22 Acorn jet nebulizer, typical adult ventilator settings, and a 3-ml nebulizer solution volume, 5.4% of the nebulizer dose reached beyond the end of the ET tube. This was increased by increasing the inspiratory time, reducing the respiratory rate or respiratory minute volume, and by repositioning the nebulizer on the inspiratory limb of the Y-piece and was reduced by slowing the driving gas flow to the nebulizer. Under the same conditions, delivery was 3.1 and 4.4% using the Samsonic and Fisoneb ultrasonic nebulizers, respectively. Increasing the fill volume and the addition of an aerosol storage chamber increased delivery with all three nebulizers. These experiments suggest some simple ways of improving aerosol delivery during mechanical ventilation, including increasing the volume of nebulizer fill, repositioning the nebulizer in the ventilator circuit, adding an aerosol storage chamber, and adjusting ventilator settings to maximize delivery.

Adult↗
PubMed1992

Treatment of combined renal failure and lactic acidosis by haemofiltration.

Twelve patients with renal failure and type A lactic acidosis were treated with haemofiltration during a 30-month period. The first three patients received only lactate-buffered replacement fluid and rapidly succumbed despite the infusion of large quantities of sodium bicarbonate. Bicarbonate-buffered replacement fluid was used for the remaining nine patients, of whom three survived. Haemofiltration with bicarbonate-buffered replacement fluid is an effective method of replacing renal function for this group of critically-ill patients.

Acidosis, Lactic↗
PubMed1987

The acute haemodynamic effects of intravenous verapamil in patients with chronic obstructive airways disease.

The haemodynamic effects of a single intravenous dose of verapamil have been investigated in patients with chronic obstructive airways disease both during an acute exacerbation and when in a stable clinical condition and compared with the effects of oxygen administered by nasal cannulae. In five patients studied during an episode of acute on chronic hypoxaemia (mean PaO2 = 5.4 kPa) there was a significant fall in pulmonary vascular resistance (p less than 0.03) following intravenous verapamil (10 mg) without any reduction in PaO2, cardiac index or oxygen delivery. Subsequent administration of oxygen by nasal cannulae at 2 l/min for 30 min produced similar pulmonary haemodynamic changes: pulmonary vascular resistance fell by 17 +/- 3 per cent following oxygen and by 22 +/- 4 per cent following verapamil. In a similar group of five patients in a stable clinical condition (mean PaO2 = 7.3 kPa) neither oxygen nor verapamil administered during acute exacerbations produced any significant changes in pulmonary vascular resistance, cardiac index or oxygen delivery.

Acute Disease↗
PubMed1986

Intermittent hypoxia in patients with unexplained polycythaemia.

The aetiology of polycythaemia is unclear in up to 30% of patients. Twenty patients with unexplained polycythaemia were investigated to see whether they had an intermittent hypoxic stimulus to erythropoiesis that was undetected by conventional investigations for hypoxic secondary polycythaemia. Overnight polygraphic sleep studies showed that five patients had prolonged nocturnal hypoxaemia. Their arterial oxygen saturation was below 92%, the level at which appreciable hypoxic stimulation of erythropoiesis occurs, for 26-68% of the time for which they were studied. Considerable evidence is accumulating that intermittent hypoxia is a potent stimulus to erythropoiesis, and clinicians should consider the possibility of nocturnal hypoxia in patients with unexplained polycythaemia. Appropriate investigation will lead to the correct diagnosis of polycythaemia secondary to hypoxia in some cases previously regarded as idiopathic, and treatment may then be planned accordingly.

Adult↗
PubMed1986

Irritable bowel syndrome: is a barium enema necessary?

A retrospective analysis was made of 114 new patients attending a gastroenterology clinic, in whom the initial clinical diagnosis was irritable bowel syndrome. Barium enemas were performed in 84 patients (74%), 15 of whom were found to have significant other disease. In each case this would have been suspected from the routine haematological and biochemical screening tests. It is suggested that, in the investigation of patients under 50 years of age presenting to a gastroenterology clinic with a typical history of irritable bowel syndrome, a barium enema should only be performed if the clinical examination, sigmoidoscopy, rectal biopsy or routine blood tests are abnormal. This policy would reduce substantially the number of normal barium enemas performed.

Adult↗
PubMed1985

Homeostasis model assessment: insulin resistance and beta-cell function from fasting plasma glucose and insulin concentrations in man.

The steady-state basal plasma glucose and insulin concentrations are determined by their interaction in a feedback loop. A computer-solved model has been used to predict the homeostatic concentrations which arise from varying degrees beta-cell deficiency and insulin resistance. Comparison of a patient's fasting values with the model's predictions allows a quantitative assessment of the contributions of insulin resistance and deficient beta-cell function to the fasting hyperglycaemia (homeostasis model assessment, HOMA). The accuracy and precision of the estimate have been determined by comparison with independent measures of insulin resistance and beta-cell function using hyperglycaemic and euglycaemic clamps and an intravenous glucose tolerance test. The estimate of insulin resistance obtained by homeostasis model assessment correlated with estimates obtained by use of the euglycaemic clamp (Rs = 0.88, p less than 0.0001), the fasting insulin concentration (Rs = 0.81, p less than 0.0001), and the hyperglycaemic clamp, (Rs = 0.69, p less than 0.01). There was no correlation with any aspect of insulin-receptor binding. The estimate of deficient beta-cell function obtained by homeostasis model assessment correlated with that derived using the hyperglycaemic clamp (Rs = 0.61, p less than 0.01) and with the estimate from the intravenous glucose tolerance test (Rs = 0.64, p less than 0.05). The low precision of the estimates from the model (coefficients of variation: 31% for insulin resistance and 32% for beta-cell deficit) limits its use, but the correlation of the model's estimates with patient data accords with the hypothesis that basal glucose and insulin interactions are largely determined by a simple feed back loop.

Adult↗
PubMed1985

Yersinia colitis associated with Crohn's disease.

A previously healthy patient developed serologically-proven Yersinia pseudotuberculosis enterocolitis and made a complete recovery. Over a year later, further gastrointestinal symptoms developed and Crohn's disease was diagnosed. The possible relevance to the aetiology of Crohn's disease is discussed.

Adult↗
PubMed1985

A multinational comparison of drug treatment in patients with cerebrovascular disease.

We have compared the frequency with which various drugs were used in patients with cerebrovascular disease in five countries (UK, Italy, Indonesia, Spain and Yugoslavia). There were very large variations in the use of anti-oedema agents, 'cerebral vasodilators', and vitamins, which were not explained by differences in the populations studied. This variation has probably less to do with any scientific validation for the various treatments, which in most cases does not exist, than with medical 'fashion' and commercial pressures. Large variations in prescribing habits for what is thought to be the same disease are undesirable, and reflect a dearth of facts and adequate clinical trials.

Aged↗