PubMed Health⌕ Search

Biomedical subjects

D Denison

Publications and source records attributed to D Denison.

10 recordsLinked to original sources
PubMed1993

Lung function in white children aged 4 to 19 years: I--Spirometry.

OBJECTIVE: A study was performed to produce reference standards for spirometric lung function in white children and to calculate standard deviation scores adjusted for gender and pubertal stage. METHODS: A cross sectional study was made of 772 white children aged 4.6 to 18.8 years (455 male) tested on an OHIO 840 spirometer and assessed anthropometrically and pubertally. RESULTS: Before puberty there was a linear increase in all lung function measurements with height. During puberty a sudden increase occurred, but subsequently the relationship was again linear. No simple single equation described this pattern. Advanced puberty in younger children conferred a respiratory advantage, whilst delayed puberty resulted in the converse. Girls had poorer volumes per unit height, but young girls had superior airflow/unit lung volume. In both sexes lung volumes and flows bore a constant relationship to external thoracic dimensions. CONCLUSIONS: Puberty has a dramatic effect on lung function. Regression equations for predicted values of lung function measurements and for calculation of standard deviation scores are given (with pubertal correction factors) for each gender.

Adolescent↗
PubMed1993

Lung function in white children aged 4 to 19 years: II--Single breath analysis and plethysmography.

OBJECTIVE: A study was performed to determine reference ranges for whole body plethysmographic gas volumes and single breath gas transfer in healthy prepubertal and pubertal schoolchildren. METHODS: The study was performed in 772 white London schoolchildren (455 male) who were clinically examined, assessed auxologically and, in 63% of cases, pubertally staged. Regression equations for the calculation of standard deviation scores were derived. RESULTS: Male lung function variables showed a discontinuous pattern of increase with standing height. Linear increases until puberty were followed by a sudden pubertal rise and a further increase with height which was more marked than before puberty. Correction for varying thoracic dimensions eliminated these changes. In females a smoother curvilinear relationship was observed with no correction possible for thoracic size. CONCLUSIONS: Male puberty leads to profound changes in pulmonary function mostly related to thoracic size, an effect not observed in females.

Adolescent↗
PubMed1985

Some observations on the role of the abdomen in breathing in patients on peritoneal dialysis.

We studied a total of 29 patients on continuous ambulatory peritoneal dialysis (CAPD), who had no present or past respiratory impairment, before and after drainage of dialysate (2.324 +/- SE 0.033 litres). We measured spirometry, lung volumes and carbon monoxide transfer sitting and supine in 20 patients. The only statistically significant changes on drainage were a small increase in supine functional residual capacity (+214 +/- SE 61 ml, P less than 0.01) and a small fall in supine peak expiratory flow rate (-26.6 +/- SE 12.1 litres/min, P less than 0.05). Measurement of maximal mouth and transdiaphragmatic pressures in ten patients made under the same circumstances showed no statistically significant changes on drainage. A model of the abdomen demonstrates that fluid distension is likely to be better tolerated than gaseous distension, and review of previous studies suggests that a wide range of changes in intraabdominal fluid volume can be tolerated without respiratory embarrassment. These results suggest that fluid volumes used for CAPD do not interfere with breathing in patients with previously normal lungs. The nature of the mechanisms compensating for the fluid suggests that patients with chest disease should be able to tolerate this form of dialysis.

Abdomen↗
PubMed1984

Temperature corrections in routine spirometry.

Forced expiratory volume (FEV1) and forced vital capacity (FVC) were measured in nine normal subjects with three Vitalograph and three rolling seal spirometers at three different ambient temperatures (4 degrees C, 22 degrees C, 32 degrees C). When the results obtained with the rolling seal spirometer were converted to BTPS the agreement between measurements in the three environments improved, but when the Vitalograph measurements obtained in the hot and cold rooms were converted an error of up to 13% was introduced. The error was similar whether ambient or spirometer temperatures were used to make the conversion. In an attempt to explain the behaviour of the Vitalograph spirometers the compliance of their bellows was measured at the three temperatures. It was higher at the higher temperature (32 degrees C) and lower at the lower temperature (4 degrees C) than at the normal room temperature. These changes in instrument compliance could account for the differences in measured values between the two types of spirometer. It is concluded that the ATPS-BTPS conversion is valid and necessary for measurements made with rolling seal spirometers, but can cause substantial error if it is used for Vitalograph measurements made under conditions other than normal room temperature.

Forced Expiratory Volume↗
PubMed1980

Clinical and haemodynamic effects of diazoxide in primary pulmonary hypertension.

Diazoxide was injected into the pulmonary artery in nine patients with primary pulmonary hypertension. There was no significant change in pulmonary artery pressure, which fell by more than 10 mmHg in only two patients. The pulmonary blood flow increased in all patients as a result of a fall in pulmonary vascular resistance (by 4 to 17 units). Systematic vasuclar resistance also fell as expected in all patients. Oral diazoxide was given to seven patients, two of whom showed sustained clinical improvement while remaining on treatment (400 to 600 mg daily). Five patients were unable to tolerate the drug, because of nausea and sickness (two), peripheral oedema requiring large doses of diuretics (four), diabetes (three), and postural hypotension (one). Hirsutes was troublesome in the two patients remaining on treatment. Diazoxide may be useful in the management of some patients with primary pulmonary hypertension, but its use is limited by the frequency of side effects. Our results suggest that examination of othe potent vasodilators may be worth while.

Administration, Oral↗
PubMedDate not supplied

Optical measurement of the change in trunk volume with breathing.

Optical mapping provides three-dimensional information about the size and shape of the trunk. We have used the technique to measure and partition the volume change of the trunk with breathing in upright subjects. In 13 subjects, 12 of whom were normal and one scoliotic, respired volume could be measured with an average error (+/- SEM) of 170 +/- 20 ml. In one of the normal subjects, 24 measurements of respired volume were in error by, on average, 120 +/- 20 ml. In a further eight normal subjects, partitioning of ventilation showed that the anterior trunk contributed 91 +/- 12%, the back 9 +/- 12%, the upper trunk 43 +/- 4%, the lower trunk 57 +/- 4% and the right and left sides 50 +/- 2% each, to a vital capacity expiration. The measurements of respired volume suggest that the technique is sufficiently accurate for clinical purposes, but it offers the added advantage that the information generated can be used to determine the spatial distribution of each breath.

Adult↗