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Biomedical subjects

A Bush

Publications and source records attributed to A Bush.

At least 145 records · Page 8Linked to original sources
PubMed1998

Complications of modified Blalock-Taussig shunts mimicking pulmonary disease.

The modified Blalock-Taussig shunt is commonly performed as early palliation in cyanotic congenital heart disease. To highlight unusual diagnostic problems in such patients, two cases are reported in whom shunt complications were initially diagnosed as lobar pneumonia and tuberculosis, respectively. The children, an 8 month old boy and a 3 year old boy, had false aneurysm secondary to infection of the graft and dilatation of the left pulmonary artery caused by blood flow through the shunt, respectively.

Cardiac Surgical Procedures↗
PubMed1998

Distal 10q trisomy syndrome with unusual cardiac and pulmonary abnormalities.

Since its description in 1965, distal 10q trisomy has become recognised as a well defined, although rare syndrome, almost always the result of an unbalanced translocation. Typical features consist of psychomotor delay, a distinctive dysmorphic appearance, growth retardation, and, in some cases, cardiac, renal, and ocular abnormalities.

Abnormalities, Multiple↗
PubMed1998

Haemodynamics in children during rest and exercise: methods and normal values.

Measuring haemodynamic performance in children is either invasive, and thus unacceptable, or noninvasive when the measured variable is often remote from the true variable. Measuring only maximum performance variables relies too heavily on motivation, especially in disease groups. We describe a method for the measurement of haemodynamic performance using respiratory mass spectrometry during rest, exercise and recovery therefrom. One hundred and six healthy children (55 male, 51 female) aged 8-16.9 yrs underwent an identical exercise protocol. Following studies at rest, they initially bicycled at 25 W x m(-2), increasing every 3 min by 15 W x m(-2) until exhaustion, after which measurements were made during recovery. Effective pulmonary blood flow, stroke volume, oxygen consumption, arteriovenous oxygen difference and functional residual capacity (FRC) together with estimates of pulmonary capillary blood volume and transit time were assessed at every exercise stage using inert gas rebreathing techniques. Haemodynamic performance is highly dependent on surface area, age, gender and pubertal stage. Many parameters, for example transfer factor, demonstrate pubertal stage-dependent differences at identical workloads even after correction for size. Females have a lower capillary blood volume at rest compared to age and size-matched males, but it is equalized during exercise. FRC unexpectedly rose with exercise, and peak exercise was associated with a falling stroke volume in 91% (95% CI 84-96%) of children, a possible demonstration of Starling's law of the heart. Oxygen pulse (oxygen consumption/cardiac frequency) is a very poor marker for pulmonary blood flow. Normal values are provided for all haemodynamic parameters for rest and every exercise stage for all subgroups of children. This should allow accurate comparison of normal and disease groups in future.

Adolescent↗
PubMed1998

Airway response of children with primary ciliary dyskinesia to exercise and beta2-agonist challenge.

In primary ciliary dyskinesia (PCD), chest physiotherapy for airway clearance is essential. Exercise and inhaled beta2-agonists can produce bronchodilation thereby augmenting physiotherapy. However, both can also cause bronchoconstriction, and the effects of these stimuli in PCD are not known. In a preliminary study, the mean coefficients of variation for forced expiratory volume in one second (FEV1), forced vital capacity (FVC) and peak expiratory flow rate (PEFR) in children with PCD were determined. They were 5.4%, 4.4% and 8.4%, respectively. Twelve children with PCD and 12 normal children performed pulmonary functions under resting conditions; during and after a validated treadmill exercise test; and before and 15 min after 200 microg of inhaled salbutamol. At baseline, FEV1, FVC, forced mid-expiratory flow (FEF25-75%) and PEFR were significantly reduced in the PCD group compared with the control group. Exercise produced a significant increase in PEFR in the PCD group. There was no significant difference between the groups in response to salbutamol. Within the PCD group, exercise produced a significantly greater increase in PEFR than beta2-agonist therapy. In conclusion, in children with primary ciliary dyskinesia there is evidence of obstructive pulmonary disease. In these children, exercise is a more potent stimulus for bronchodilation than by inhaled beta2-agonists. Enhancement of airway clearance may best be achieved by encouraging patients to exercise before physiotherapy rather than by inhaling beta2-agonists, but the effects of each should be assessed for each individual before instigating treatment.

Administration, Inhalation↗
PubMed1998

Holding the baby: head downwards positioning for physiotherapy does not cause gastro-oesophageal reflux.

The head-downwards tipped position for physiotherapy has been claimed to exacerbate gastro-oesophageal reflux (GOR) in infants with cystic fibrosis (CF). This was investigated using lower oesophageal pH monitoring during physiotherapy. Twenty-one infants (age range 1-27 months) with respiratory disorders (CF=11), undergoing lower oesophageal pH monitoring were recruited. Subjects received two physiotherapy episodes in random order, A/B or B/A, 12 h apart. A began the gravity-assisted positioning head downward tip for: right lower lobe, middle lobe, left lower lobe and lingula; then supine with no tip for anterior segments of the upper lobes followed by apical segments of upper lobes in a sitting position. B was in the reverse order. Intermittent chest clapping was carried out for 4 min in each position by a physiotherapist blinded to the pH data. During episode A, the median change in pH from baseline was -0.32 (range -2.07 to +1.0) in non-CF subjects (NS) and -0.52 (range -2.7 to +0.52) in CF subjects (p<0.02). During episode B, the median change in non-CF subjects was -0.1 (NS; range - 1.7 to -0.15) and in CF subjects was -0.05 (NS; range -0.67 to +0.5). There was no order effect for positioning. In the CF subjects the sitting position was twice as likely to have the lowest pH measurement during physiotherapy than the other positions (p<0.04). In conclusion, the head-downward tipped positioning for physiotherapy treatment neither induces nor aggravates gastro-oesophageal reflux. There is no justification for routinely changing the way in which infant physiotherapy is carried out.

Analysis of Variance↗
PubMed1998

Primary ciliary dyskinesia: diagnosis and standards of care.

Primary ciliary dyskinesia (PCD) is characterized by disease of the upper and lower respiratory tract, in association with visceral mirror image arrangement in 50% of cases, due to abnormal structure and/or function of cilia. The purpose of this paper is to review the clinical features, diagnosis and management of PCD. Presentations include neonatal respiratory distress, recurrent lower respiratory tract infection, chronic rhinosinusitis and male infertility. PCD enters the differential diagnosis of bronchiectasis, atypical asthma, and unusually severe upper airway disease. Diagnosis is by a cascade of investigations, starting with the saccharin test in patients older than 10 yrs; ciliary beat frequency and pattern on light microscopy; and electron microscopy to assess ciliary morphology and orientation. It is important not to confuse primary and secondary ciliary abnormalities. Nasal nitric oxide is low in PCD, and this measurement shows promise as a screening test for PCD. Diagnosis is important, in order to prevent the development of bronchiectasis and to avoid any unnecessary otorhinolaryngological procedures. Regular follow-up is essential, and management should be multidisciplinary, with input from centres with a special interest in PCD, having access to paediatric and adult chest physicians, otolaryngologists and audiological physicians, physiotherapists, counselling services and fertility clinics. The prognosis is good, but morbidity can be considerable if PCD is incorrectly managed.

Adult↗
PubMed1998

Effect of hand dominance on bone mass measurement in sedentary individuals.

The aim of this study was to determine in healthy sedentary subjects the effect of hand dominance on side-to-side difference in bone area and bone mass for upper and lower extremities. Dual-energy X-ray absorptiometry (DXA) measurements of both forearms and hips were performed on 193 right-handed and 20 left-handed subjects as determined by self-report. Scan acquisition and scan analyses were performed by one investigator, but all scan pairs were independently assessed for symmetry of positioning and movement artifacts by three investigators. Results show that DXA measurements between sides may be highly correlated regardless of the symmetry of the scan pair. However, asymmetric DXA scan pairs may have more than twice the side-to-side difference found in symmetric DXA scan pairs at the hip. Side-to-side differences between subregions were greater than the differences between measurements at the total radius, ulna, or hip. For symmetric pairs of DXA scans, the dominant forearm has significantly higher bone area and bone mineral content (BMC). Bone mineral density (BMD) was significantly higher only in the ulna of the dominant forearm. However, the nondominant forearm has higher values than dominant forearm in at least one DXA measurement in >24% of the subjects. There were no significant differences in any DXA measurements between hips, and higher DXA measurements did not occur significantly more frequently at the hip corresponding to the dominant hand. We conclude that healthy sedentary subjects tend to have proportionally higher bone area and BMC in the dominant forearm that results in similar BMD between dominant and nondominant forearms. This relationship does not appear to be applicable to measurements at the hip. In addition, there is a significant proportion of subjects with higher bone area and BMC in the nondominant extremities. Thus, in sedentary subjects, the consistency in the use of same extremity and the consistency in scan acquisition techniques and scan analyses is of greater importance than the selection of an extremity based on hand dominance in DXA studies.

Journal Article↗
PubMed1997

Cardiopulmonary interactions after Fontan operations: augmentation of cardiac output using negative pressure ventilation.

BACKGROUND: The low-output state is the chief cause of morbidity and mortality after Fontan operations. An alternative hemodynamic tool would be a welcome addition for these patients, who are typically resistant to conventional therapeutic measures. METHODS AND RESULTS: The hemodynamic effects of conversion from conventional intermittent positive pressure ventilation (IPPV) to cuirass negative pressure ventilation (NPV) was investigated in nine acute postoperative Fontan patients on the pediatric intensive care unit and nine anesthetized patients undergoing cardiac catheterization in the convalescent phase after Fontan operations. Pulmonary blood flow was measured using the direct Fick method during IPPV and after a brief period of NPV. In one subgroup of patients, pulmonary blood flow was measured again after reinstitution of IPPV, and in a second subgroup, pulmonary blood flow was measured after an extended period of NPV. A brief period of NPV increased pulmonary blood flow from 2.4 to 3.5 L x min(-1) x /m(-2), with a mean increase of 42%. Pulmonary blood flow continued to improve, with a total increase of 54% after an extended period of NPV. Values fell toward baseline after reinstitution of IPPV. Heart rate was unchanged during NPV, and the improvement in pulmonary blood flow was achieved by an increase in stroke volume from 25 mL/m2 to 37 mL/m2. CONCLUSIONS: Through improvement of the stroke volume alone, NPV brought about a marked increase in the pulmonary blood flow and, hence, cardiac output of Fontan patients. An improvement in cardiac output of this order, and by this mechanism, is currently unmatched by any therapeutic alternatives.

Adolescent↗
PubMed1997

Retrospective review of the effects of rhDNase in children with cystic fibrosis.

Trials of rhDNase in mixed groups of adults and children with cystic fibrosis (CF) have demonstrated improvements in lung function and well-being. This has led to many pediatric CF patients receiving regular rhDNase therapy although their response to treatment may not be the same as that seen in adults. We have retrospectively reviewed the effects of rhDNase during the first year of therapy in 65 children receiving the drug at two tertiary referral centers. Outcome measures included changes in lung function, oxygen saturation, use of intravenous antibiotics, and subjective improvement. Median baseline lung function (% of predicted) was 45% for forced expiratory volume in 1 second (FEV1) and 58% for forced vital capacity (FVC). At 3-4 months following initiation of therapy the group demonstrated median (95% CI) increases of 14.2% (95% CI 7.3; 21.1%) in FEV1 and 7% (0; 14%) in FVC. Within this wide scatter of responses, one-quarter of children deteriorated, but almost 50% showed significant improvements of > 10%. A similar pattern was seen at 9 months, with median increases for the group of 11.1% (0; 18.8%) in FEV1 and 5.6% (0; 17%) in FVC, again with approximately one-third of the group deteriorating and one-half improving significantly. Intravenous antibiotic use decreased significantly. Almost all the children (89%), including those with a fall in lung function, described subjective improvement. There were no predictive markers at baseline of a good response to the drug. However, there was a good correlation between lung function response at 3 months and that at 6, 9, and 12 months. Thus, children respond to rhDNase at least as well as adults, and a therapeutic trial is justified in those over 5 years with significantly impaired lung function. Response is highly variable, making careful individual assessment mandatory. Baseline characteristics are not useful in predicting those children who will respond well to treatment, but long-term response to the drug can be predicted on the basis of spirometric improvement at 3 months. Therefore, this would be a useful time period for a therapeutic trial.

Adolescent↗
PubMed1997

Congenital diaphragmatic hernia misdiagnosed as tension pneumothorax.

Drainage of the pleural space is undertaken as an emergency when there is respiratory distress and the radiological appearance of mediastinal shift. We present two cases in which the initial diagnosis was tension pneumothorax and chest drains were inserted. In both cases, the diagnosis turned out to be congenital diaphragmatic hernia.

Child↗
PubMed1997

Exhaled nitric oxide measurements in normal and asthmatic children.

The aim of this study was to determine whether we could measure exhaled nitric oxide (NO) levels in children, and whether the same pattern of exhaled NO concentrations was observed in asthmatic and normal children as had been seen in adults. Using a chemiluminescence NO analyzer, we measured NO in exhaled air both directly and through a T-piece allowing us to measure carbon dioxide (CO2), mouth pressure, and expiratory flows. In 39 normal children the mean peak exhaled NO was 49.6 parts per billion (ppb) (SD 37.4) when all expired gas passed directly through the NO analyzer, and 29.7 ppb (SD 27.1) when expiration occurred through a T-piece. The results were significantly higher in 15 asthmatic subjects on bronchodilator therapy only [126.1 ppb (SD 77.1) direct (P < 0.001), and 109.5 ppb (SD 106.8) via T-piece (P < 0.001)]. In 16 asthmatics on regular inhaled corticosteroids the mean peak exhaled levels were significantly lower 48.7 ppb (SD 43.3) direct (P < 0.001) and 45.2 ppb (SD 45.9) via T-piece (P < 0.01). There was no difference between the normal children and the asthmatic children on regular inhaled corticosteroids (P = 0.9 direct, P = 0.2 via T-piece). There were no significant differences in carbon dioxide levels, mouth pressure, duration of expiration and expiratory flows between the different groups, and no difference between carbon dioxide levels, mouth pressure and duration of expiration between the two methods (direct and T-piece). In 6 asthmatic children mean peak exhaled levels on NO fell from a median peak level of 124.5 ppb to 48.6 ppb when measured before and 2 weeks after commencement of inhaled corticosteroid treatment. The measurement of exhaled NO levels may be useful as a noninvasive means of monitoring children with asthma.

Adolescent↗
PubMed1997

Cardiopulmonary physiology after surgical closure of asymptomatic secundum atrial septal defects in childhood. Exercise performance is unaffected by age at repair.

AIMS: Most secundum atrial septal defects, once diagnosed, are corrected at a young age. The evidence to justify early vs delayed or even non-closure is equivocal and little is known regarding long-term effects of later closure. This is particularly pertinent to those patients awaiting transcatheter closure of their defect for whom a device is only just becoming available. We examined the exercise cardiorespiratory physiology of children surgically treated for an isolated secundum defect. METHODS AND RESULTS: One hundred and six healthy control children and 22 children more than 6 months after surgical repair for an isolated secundum atrial septal defect were studied. All were asymptomatic. Measurements of effective pulmonary blood flow, stroke volume, arteriovenous oxygen difference, minute ventilation, heart rate, oxygen consumption and carbon dioxide production were made using a quadrupole mass spectrometer during rest and graded exercise. Data from the normal children allowed calculation of z scores for the atrial septal defect group matched for age, sex, pubertal stage and surface area. Maximal exercise performance was equal between control and atrial septal defect groups, however, the atrial septal defect group had a significantly greater effective pulmonary blood flow and stroke volume but a lower heart rate than controls at a given exercise stage. Stroke volume abnormalities were most closely related to duration of follow-up (29% of the variance explained, P < 0.01) rather than age at surgery. CONCLUSIONS: We were unable to show a medium term benefit from early surgery for an asymptomatic secundum atrial septal defect during exercise. The clinical relevance of the haemodynamic differences that do exist remains unclear.

Adolescent↗
PubMed1997

Attitudes toward standardized data collection.

BACKGROUND AND PURPOSE: Clinical databases will gain importance as physical therapists need to determine the effectiveness and justify the expense of treatment. Obstacles impeding participation in standardized data collection need to be identified and addressed to construct high-quality databases. SUBJECTS: Subjects were clinicians involved in patient care in a multisite physical therapy/occupational therapy practice that had initiated a standardized data collection program. METHODS: Questionnaires, asking about participation in the data collection project, were distributed to participating clinics. Factor analysis identified attitudes toward standardized data collection. Relationships between efforts to learn standardized methods, attitudes, clinic and clinician characteristics, and levels of participation in the project were investigated. RESULTS: Most respondents (66%) had made some effort to learn the standardized procedures. Five attitudes were identified: inconvenience, acceptance of operational definitions, automation, paperwork, and training. CONCLUSION AND DISCUSSION: Inconvenience of data collection and training in standardized methods need to be addressed to construct large, high-quality databases.

Adult↗
PubMed1997

Cardiovascular effects of intravenous midazolam after open heart surgery.

Midazolam is the sedating agent of choice in many paediatric intensive care units, and is usually administered as a continuous intravenous infusion with or without a preceding bolus dose. Ten haemodynamically stable children, ventilated in the early postoperative period after cardiac surgery and receiving intravenous morphine infusions, were given an intravenous bolus followed by a continuous infusion of midazolam. Haemodynamic data were recorded before the bolus, and 15 minutes and one hour later. A bolus of midazolam lowered the cardiac output by 24.1%. Arterial blood pressure, oxygen consumption, and mixed venous oxygen content fell significantly. There was a tendency for all variables subsequently to recover towards baseline values, within one hour, during a continuous infusion. An intravenous bolus of midazolam causes a transient but unwanted fall in cardiac output. It is suggested that in children who are receiving intravenous opiates, its use in the early postoperative period be limited to a continuous infusion.

Adolescent↗
PubMed1997

Relation between insulin-like growth factor-I, body mass index, and clinical status in cystic fibrosis.

OBJECTIVES: Despite improved nutrition and intensive treatment, subjects with cystic fibrosis have difficulty in maintaining anabolism during intercurrent infections, which can result in reduced body mass index and impaired skeletal growth. Insulin-like growth factor-I (IGF-I) and its binding protein IGFBP3 are sensitive to changes in nutritional status. The aim of this study was to determine the relation between circulating concentrations of these peptides, body mass index, and clinical status in cystic fibrosis. METHODS: Serum concentrations of IGF-I and IGFBP3 were measured in 197 subjects (108 males, 89 females; mean age 9.69 years, range 0.41-17.9 years) and these data were analysed with respect to body mass index, pubertal stage, and clinical status as assessed by Shwachman score and forced expiratory volume in one second (FEV1). RESULTS: The mean height SD score of the children studied was -0.2 (SD 1.14) and the body mass index SD score -0.26 (1.4). The body mass index SD score declined with increasing age (r = -0.18) and paralleled changes in IGF-I concentrations, which also declined. The IGF-I SD score (calculated from control data) correlated with age (r = -0.53). The abnormalities were most obvious during late puberty, when IGF-I and IGFBP3 concentrations were significantly reduced compared with those in control subjects matched for pubertal stage. The IGF-I SD score correlated with height SD score (r = 0.14) and the decline in IGF-I concentrations with the fall in body mass index SD score (r = 0.42). IGF-I SD scores also correlated with the Shwachman score (r = 0.33) and FEV1 (r = 0.17). CONCLUSIONS: The close relation between declining IGF-I and IGFBP3 concentrations and body mass index in patients with cystic fibrosis may simply reflect poor nutritional status and insulin hyposecretion. Nevertheless, IGF-I deficiency could also contribute towards the catabolism observed in these patients, and IGF-I SD scores correlated with other measures of clinical status such as the Shwachman score and FEV1.

Adolescent↗