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Biomedical subjects

C S Beardsmore

Publications and source records attributed to C S Beardsmore.

At least 37 records · Page 2Linked to original sources
PubMed1994

Pulmonary function in infants with cystic fibrosis: the effect of antibiotic treatment.

Since 1982 all infants born within the East Anglian Regional Health Authority have been screened for cystic fibrosis. Between April 1985 and April 1992 infants identified in this way have been entered into a randomised prospective controlled trial of antibiotic prophylaxis. Approximately half the infants received continuous oral flucloxacillin and the remainder received antibiotics when clinically indicated. Infants underwent tests of respiratory function at 3-4 months and at 1 year of age. Measurements of thoracic gas volume and airway conductance were made with an infant whole body plethysmograph, and maximum expiratory flow by the 'squeeze' technique. A total of 73 tests was performed of 42 infants. To facilitate comparisons, measurements were expressed as scores. The mean values of the scores for the two groups of infants fell within normal limits. There was no difference between the treatment groups at either age. A reduction in airways conductance was observed between the two tests.

Administration, Oral↗
PubMed1994

Clinical findings and respiratory function in infants following repair of oesophageal atresia and tracheo-oesophageal fistula.

Survival rates for infants undergoing surgical repair of oesophageal atresia with tracheo-oesophageal fistula (OA-TOF) have improved dramatically, but this condition remains associated with substantial morbidity. Most studies of patients following OA-TOF repair have concentrated on school-age and older people; whereas, the most hazardous period is infancy. We aimed to assess respiratory function in a group of infants following primary operative repair, and to relate the results to clinical findings during the first year of life. We studied 16 infants within 3 months of primary repair of OA-TOF. Measurements were made of maximum expiratory flow at functional residual capacity (VmaxFRC), thoracic gas volume (TGV) and airways resistance (Raw). Ten infants had tests repeated, usually to assess progress alongside continuing symptoms, or to ascertain improvement following additional surgery. Seven infants had essentially normal initial respiratory function tests, and six remained either symptom-free or developed only minor clinical problems. One infant subsequently developed stridor, with spontaneous improvement towards the end of the first year. The remaining nine infants had abnormal initial respiratory function tests: one was symptom-free at that time. The remainder developed respiratory and/or gastro-oesophageal symptoms. The functional abnormalities appeared to reflect the severity of the clinical problems encountered. We conclude that respiratory function testing in infants following OA-TOF repair may augment the value of clinical appraisal, help define postoperative respiratory status, and provide a general guide to likely clinical progress.

Airway Resistance↗
PubMed1993

Comparison of peripheral chemoreceptor responses in monozygotic and dizygotic twin infants.

The peripheral chemoresponses of infant twin pairs were determined using a single-breath hyperoxic stimulus. A total of 43 twin pairs of comparable gestation and birth weight were studied during sleep at a mean (SD) age of 8 wk (1.4) while alternately breathing either air or 16% oxygen in nitrogen. Infants responded to a single breath of 100% oxygen by a reduction in ventilation; the mean (SEM) reduction in air was 273 ml/min (10.6) and in 16% oxygen 560 ml/min (18.4). Within-pair variances were compared in 14 monozygotic and 28 dizygotic pairs utilizing combined responses (air + 16% oxygen) computed for measurements made in behavioral quiet sleep and in 9 monozygotic and 20 dizygotic pairs for whom data were complete in polygraphically confirmed quiet sleep. The variance of responses within dizygotic twin pairs was greater than in monozygotic pairs when expressed in ml/min: F ratio 4.11 (p = 0.005) for all data and F ratio 7.67 (p = 0.003) in quiet sleep. Expressed in ml/min/kg the difference was less significant: F ratio 1.83 (p = 0.126) for all data and F ratio 3.46 (p = 0.039) in quiet sleep. Gender, birth weight, and birth order had no effect on these findings. This closer similarity of response in monozygotic twin pairs is explained by proposing a high degree of heritability for the response.

Chemoreceptor Cells↗
PubMed1992

A scoring system for lung function tests in infants.

Measurements of thoracic gas volume (TGV), airway resistance (Raw), and airway conductance (Gaw) were calculated in a group of 42 normal infants using a whole-body plethysmograph. Maximum expiratory flow at functional residual capacity was measured in a separate group of 108 normal infants. Using data obtained from these infants the following regression equations were calculated: Gaw (L.s-1.cmH2O) = -0.0475 + 0.00164 x length (cm) square root of TGV (mL1/2) = -3.22 + 0.263 x length (cm) VmaxFRC (mL.s-1) = -173 + 5.2 x length (cm). The standard errors of prediction are a measure of the scatter of individual results from the normal population about the true regression line. They were used to define limits of the normal ranges for these tests of lung function, and to develop a scoring system. This approach is preferable to expressing results as percent predicted, which gives no indication of how likely a measurement is to be within normal limits.

Age Factors↗
PubMed1991

Asthma severity at night during recovery from an acute asthmatic attack.

This study was undertaken to investigate the severity of night time asthma in children in hospital recovering from an acute attack of asthma. Twenty two children aged 5-14 years were studied. Coughing 'epochs' overnight varied from one to 156 (median 39.5) and mean overnight arterial oxygen saturation (Sao2) from 82 to 98% (mean 91.3). Log values for cough showed a correlation with Sao2. An Sao2 of less than 90% was invariably associated with coughing but Sao2 above 95% did not preclude cough. Peak flow measured in the morning or evening correlated with Sao2 but not with log cough, and clinical examination scores showed no correlation with overnight measurements. Night time Sao2 correlated better with daytime tests of lung function than log cough. In general, night time indices of severity reflected daytime pulmonary function status but night cough was sometimes prominent in less severely affected cases. At the time of discharge, clinical indices of severity underestimated the degree of functional impairment at night.

Acute Disease↗
PubMed1991

Gastro-oesophageal reflux and respiratory function in infants with respiratory symptoms.

This study aimed to define the incidence and severity of gastro-oesophageal reflux (GOR), as measured using 24 hour oesophageal pH monitoring, in 38 infants with recurrent respiratory symptoms and to relate these findings to measures of respiratory function. Twenty one infants had a pH under 4 for more than 5% of the time (one definition of abnormal GOR) and nine had GOR exceeding age related normal values. Maximum expiratory flow at functional residual capacity was reduced in 37 infants, airways resistance was raised in 19 infants, and thoracic gas volume was abnormal in 11 infants. There was no association between indices of GOR and measures of lung function whether assessed by correlation or by chi 2 analysis for normal versus abnormal values. However, individual infants appeared to have respiratory symptoms produced by GOR. This suggests that host responsiveness to GOR may be of greater relevance than the amount of GOR.

Female↗
PubMed1991

The effect of a single breath of 100% oxygen on breathing in infants at 1, 2, and 3 months of age.

Sequential measurements of the ventilatory response to a single breath of oxygen delivered during quiet sleep were made in 16 healthy infants between 1 and 3 months of age, alternately breathing air and 16% oxygen in nitrogen. At 1 month the response to a single breath of oxygen during normoxia was a decrease in minute ventilation of 264 +/- 34.2 (SEM) ml.min-1 during the 10-s period following the stimulus (p less than 0.001). During mild hypoxia the decrease in ventilation averaged 471 +/- 49.1 (SEM) ml.min-1 (p less than 0.001). The difference in response between measurements in air and mild hypoxia was significant (p less than 0.001). By the age of 3 months, the absolute ventilatory response to a single breath of oxygen increased significantly in normoxia by 118 +/- 35.2 ml.min-1 (p less than 0.01); the test response to breathing 16% oxygen paralleled the response to normoxia and was on average 254 +/- 26.6 ml.min-1 larger than the response when breathing air (p less than 0.001). When the three age groups were compared, calculating the response per killigram body weight showed that the response was similar at all three ages tested. These data provide a reference baseline for normal infants.

Chemoreceptor Cells↗
PubMed1990

Airway function in infants with vascular rings: preoperative and postoperative assessment.

Aortic arch anomalies in infancy often cause intrathoracic airway obstruction. Airway function was assessed as part of the diagnostic evaluation in six symptomatic infants both by plethysmography and using a chest compression technique to obtain partial flow-volume loops. Two infants had normal intrathoracic airway function and their symptoms were unrelated to aortic arch abnormalities. The remaining four had complete vascular rings (three double aortic arch, one pulmonary sling) and had increased expiratory airway resistance (Raw) (mean Raw = 700% predicted) and greatly decreased maximum flow rates at functional residual capacity (VmaxFRC; mean VmaxFRC = 34% predicted) with gross shape abnormalities of the flow-volume loop. Postoperatively airway function was substantially improved (mean Raw = 175% predicted, VmaxFRC = 79% predicted) but some abnormality of flow-volume loop shape remained, suggesting that tracheal dynamics were not completely normal in the early postoperative period.

Airway Obstruction↗
PubMed1990

Latent sensitisation to respiratory syncytial virus during acute bronchiolitis and lung function after recovery.

To determine whether latent sensitivity to respiratory syncytial virus antigen(s) occurs after infection, 27 infants with acute bronchiolitis were studied and compared with 15 hospital controls. Blood was collected for whole blood challenge, and histamine release was measured by a high performance liquid chromatography technique with fluorometric detection. There was a significantly greater histamine release to respiratory syncytial virus antigen(s) in those with bronchiolitis than in controls, expressed either in amount (median 154 nmol/l compared with 104 nmol/l) or percentage release (median 20% compared with 3%). There was a significant difference between index and control groups in terms of individual histamine responses. These findings strongly suggest that infants develop latent sensitivity to respiratory syncytial virus antigen(s) during the course of acute bronchiolitis. Serial lung function tests were performed in 15 infants. All infants had abnormalities of lung function at some stage, but the small numbers of subjects precluded comparison between 'sensitised' and 'non-sensitised' infants. Further study is indicated to define the relation of latent sensitisation and subsequent bronchial hyper-responsiveness after respiratory syncytial virus infection in infants.

Acute Disease↗
PubMed1989

Cough flow-volume relationships in normal and asthmatic children.

The flow-volume profile of a maximum voluntary cough resembles that of a maximum expiratory flow-volume (MEFV) curve with superimposed transient peak flows at the onset of each cough effort and portions of zero flow corresponding to periods of glottis closure. A straight line (the cough slope) can be drawn through the transient peak flows, and the ratio of MEFV-equivalent flow to the cough peak flow can be calculated. This cough ratio has been shown to fall during adult life and may be related to changes in airway compliance and cross-sectional area with age. The present study investigated the cough ratio, cough slope, and maximum flows measured from the cough flow-volume curve in a group of normal children aged 7 to 16 years. Maximum flows and the cough slope increased with height, but the cough ratio did not change with growth or age. In a similar group of asthmatic children, baseline measurements of cough showed a reduction in cough peak flow rates, MEFV-equivalent flow, and the cough ratio. These changes are related to alterations in airway compliance and cross-sectional area and are partly reversed following inhalation of a bronchodilator.

Adolescent↗
PubMed1989

Measurement of lung volumes during active and quiet sleep in infants.

The question of whether functional residual capacity (FRC) falls in infants during active sleep has been clouded by studies using different subject groups and techniques for measurements of lung volume and determination of sleep state. Twenty healthy full-term infants within the first week of life participated in the present study. Neurophysiological and behavioral criteria were used to define sleep state, and measurements of FRC were made using a specially constructed closed-circuit helium dilution system. Regularity of respiration was recorded using magnetometers on the chest and a modified respirator monitor. Results showed that no significant changes in FRC occurred, related either to sleep state or to regularity of respiration. In addition, we failed to detect any differences in FRC between the sexes.

Body Weight↗
PubMed1989

Respiratory control in infants at increased risk for sudden infant death syndrome.

There is much debate relating to possible abnormalities in respiratory control mechanisms in infants considered at increased risk for sudden infant death syndrome (SIDS). The P0.1 occlusion technique was used to assess the central respiratory response to hyperoxic hypercapnia during quiet sleep in 21 normal infants, 13 siblings of SIDS victims, and 17 infants with apparent life threatening events. The slope of P0.1 plotted against carbon dioxide concentration increased exponentially with age, independent of body weight in each group. Birth weight has a significant effect on slope with a lower weight predisposing to a lower slope. Siblings as a group had a significantly lower slope at any given age than normal infants, whereas the infants who had had apparent life threatening events were not significantly different from the controls. As intragroup variation in both siblings and control groups greatly exceeded the significant intergroup differences observed, the technique cannot identify individual infants as belonging to one or other group.

Age Factors↗
PubMed1988

Lung function in infants with cystic fibrosis.

Lung function was measured in 28 infants with cystic fibrosis and repeated in 17 of the infants during the first year of life. Thoracic gas volume (TGV) and specific airway conductance (sGaw) were measured plethysmographically and maximum forced expiratory flow at functional residual capacity (VmaxFRC) was derived from the partial expiratory flow-volume curve. At the time of the initial evaluation respiratory function was correlated with the clinical condition of the infants but not with age. There was a good correlation between sGaw and VmaxFRC when both were expressed as percentages of the predicted normal values. On the basis of the normal range for sGaw the infants were divided into two groups. Group A (n = 9), who had normal sGaw, were younger and had a lower clinical score and normal VmaxFRC and TGV values. Group B (n = 19), who had low sGaw, had increased TGV and decreased VmaxFRC. There was no correlation with age for any measure of lung function for the population as a whole. Repeat testing was undertaken at intervals in 17 representative infants. In most of these infants the relation between sGaw and VmaxFRC was maintained; there was no evidence that VmaxFRC was affected before sGaw. There was no functional evidence that the earliest changes in cystic fibrosis occur in small airways, as reflected by changes in VmaxFRC in infancy.

Airway Resistance↗