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Biomedical subjects

S Godfrey

Publications and source records attributed to S Godfrey.

At least 235 records · Page 13Linked to original sources
PubMed1975

Generalized pulmonary hyperinflation and Fallot's tetralogy in a neonate investigated by pulmonary physiological and radioisotopic methods.

An infant is described who presented a complex cardiopulmonary problem which was evaluated with the help of new physiological techniques. the infant was born at term after an emergency Caesarian section for fetal distress and was found to have meconium aspiration. He remained persistently tachypnoeic and hypoxic despite high ambient oxygen. Chest radiography suggested cystic lesions at the lung bases, and lung function tests confirmed hyperinflation with delayed nitrogen washout. In addition the child had signs of Fallot's tetralogy, and this diagnosis was confirmed by cardiac catheterization. Because of persistent hypoxia and tachypnoea disproportionate to the cardiac condition, the possibility of localized lung disease was considered. Regional lung function tests were carried out in the neonatal period and again at six months of age useing radioisotopic 13N given by both inhalation and injection. These studies showed gross ventilation/perfusion imbalance in the lungs, particularly marked at the bases, but with enough generalized abnormality to preclude the possibility of surgical intervention. The principles of the measurement of lung mechanics in the newborn by whole-body plethysmography, nitrogen washout, and regional radioisotopic spirometry are outlined. The particular value of these techniques in the evaluation of complex disorders is discussed, especially where both cardiac and pulmonary abnormalities are present.

Airway Resistance↗
PubMed1975

Cardiopulmonary responses to exercise in obese girls and young women.

A study of exercise performance was carried out in 17 obese girls and young adults. During submaximal steady-state bicycle exercise oxygen intake (Vo2) for a given work output (W) was raised in obese subjects but minute ventilation at a fixed carbon dioxide output, gas exchange, blood gases, and cardiac output at a given VO2 were similar to the values previously found for normals. In obese subjects high levels of VO2 for fixed W were also obtained on the treadmill but when these were standardized for body weight (unlike the bicycle test) it was shown that the obese girls and women exercised within the normal (expected) range of aerobic energy expenditure. During maximal performance the absolute VO2 max was the same in obese and nonobese subjects but for a given body weight, lean body mass, and leg muscle (plus) bone volume, VO2max was reduced by 23.8, 16.3, and 24.5% respectively, in the former group. It was concluded that obesity though having minimal affect on responses to submaximal exercise is nevertheless associated with a marked reduction in physiological performance at or near maximal effort.

Body Composition↗
PubMed1975

An analysis of a rebreathing method for measuring lung volume in the premature infant.

Functional residual capacity (FRC) and thoracic gas volume (TGV) were measured in 20 infants, of whom 11 were healthy preterm infants, 5 were recovering from the respiratory distress syndrome (RDS), and 4 had other pulmonary problems. In addition, some of the theoretical aspects of rebreathing techniques, including the lung to bag N2 difference at equilibrium, were studied by constructing a simple digital computer model of the system. In both the normal preterm infants and the post-RDS group, the TGV was significantly greater than the FRC (0.02 greater than P greater than 0.01), indicating the presence of trapped gas (Fig. 2). The mean time taken to reach equilibrium during rebreathng was 44 sec in the normal infants and 52 sec in the post-RDS group (Table 2). In one infant with generalized cystic lung disease, equilibrium was not achieved even after 3 min of rebreathing (Fig. 1). The computer-generated analysis of rebreathing for a normal 3-kg infant is shown in Figure 3, with an in vivo curve for comparison. The rapid equilibration of N2 was completed within 55 sec but, as in the in vivo experiments, there was a change in slope of the line afer 1.7 min. It can be seen from Table 3 that, if a small initial bag volume (11 ml) is used, 30 sec of rebreathing is adequate for equilibration only when FRC and dead space are normal, and errors would occur if either were enlarged. The computer study showed that the gradient for N2 between bag and lung at equilibrium is of the order of 0.2-0.37% which would cause a negligible error when calculating FRC and assuming that lung N2 is equal to the measured bag N2. The combined in vivo and computer studies served to validate the rebreathing technique as a method for measuring FRC, and have enabled it to be modified for use even in small or very sick infants with poor ventilation. The most useful procedure to employ would seem to be to use an initial bag volume of 150-200 ml and to continue the rebreathing for 1.5-2 min, with samples being taken for analysis at approximately 20-sec intervals.

Computers↗
PubMed1975

Exercise-induced bronchial lability in wheezy children and their families.

Studies have been caried out to investigate bronchial lability as assessed by means of standardized running exercise tests. It was found that children who had been wheezy as infants had an abnormal degree of bronchial lability, even if they were asymptomatic, and closely resembled children who had continued to wheeze. The relatives of asthmatic children displayed a high incidence of bronchial lability, atopic diseases, and positive skin tests, and a similar incidence was found in the relatives of babies with wheezy bronchitis. The difference from a control population was particularly noticeable in the healthy relatives of wheezy children. Studies in monozygotic twins have shown a very high incidence of concordance for asthma, particularly when bronchial lability is taken into account. These studies suggest a common genetic basis for wheezing in childhood, based on the inheritance of bronchial lability. The difference in responses of the actively asthmatic subject from that of other labile subjects suggests that additional environmental factors are necessary to interact with the inherited bronchial lability.

Adolescent↗
PubMed1975

The use of the treadmill for assessing exercise-induced asthma and the effect of varying the severity and duration of exercise.

Running produces a greater amount of post-exercise bronchoconstriction than other forms of exercise carried out a similar metabolic rates. The treadmill can be used to provide a standardized form of exercise when studying the asthmatic child. The severity of post-exercise bronchoconstriction depends upon the rate of working on the treadmill and the duration of exercise. A maximum response is obtained by six minutes of running at an uphill slope of 10% at a speed of 5 kmph (3 mph). Even with this type of test, there is still considerable variation in the response from time to time and greatest reporducibility is obtained by repeating the test within one week. Treadmill exercise tests may be used in the diagnosis of asthma and in the assessment of its likely severity.

Adult↗
PubMed1975

Suppression of exercise-induced asthma by salbutamol, theophylline, atropine, cromolyn, and placebo in a group of asthmatic children.

A number of drugs are known to inhibit exercise-induced asthma (EIA), but the results in some cases have been difficult to interpret due to the techniques employed. A comparative study was carried out in a group of children to investigate the effects of salbutamol, choline theophyllinate, cromolyn sodium, atropine, and placebo. The exercise test took the form of six minutes of standardized treadmill running. All the drugs, but not the placebo, were able to inhibit EIA ti a significant degree, the effect being most marked with salbutamol. Cromolyn sodium caused no bronchodilatation at rest, while all the other drugs were brondhocilators, the effect being most marked with the atropine during exercise. It was impossible to distinguish the type of drug used for inhibition of EIA if it caused bronchodilatation at rest. The manner in which an exercise test can be used to investigate the duration of action or site of action of drugs is noted.

Adolescent↗