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Biomedical subjects

A L Coates

Publications and source records attributed to A L Coates.

At least 91 records · Page 5Linked to original sources
PubMed1984

Relationship between the partial pressure of arterial oxygen and airflow limitation in children with cystic fibrosis.

To assess whether it would be possible to avoid repeated arterial blood sampling in children with cystic fibrosis, the relation between the forced expiratory flow at 25% to 75% of the vital capacity (FEF25%-75%) and the partial pressure of arterial oxygen (PaO2) was examined. The PaO2 and the logarithm of the FEF25%-75% (expressed as a percentage of that predicted) showed the strongest correlation (r = 0.89, p less than 0.001). Although this relation cannot be used when an accurate value for the PaO2 is required, it can sometimes be useful for determining the need for an arterial puncture.

Carbon Dioxide↗
PubMed1984

Short-term clinical, nutritional, and functional effects of continuous elemental enteral alimentation in children with cystic fibrosis.

Ten children with cystic fibrosis, aged 3.5 to 12 years, whose weights were lower than 90% of the expected weight for height, received high-calorie elemental enteral alimentation for four weeks. Clinical, anthropometric, and biochemical evaluations as well as blood gas analyses and chest radiograph scoring were performed in all. Pulmonary function tests were performed in the five older children, and progressive exercise tests in three. These evaluations were done before, immediately after, and two months after termination of therapy. Nutritional therapy resulted in an increase of caloric intake and in dramatic weight gain, which persisted only for a short time and was mainly related to adipose tissue accretion. No functional improvement accompanied the amelioration in nutritional status. This short-term nutritional therapy in malnourished children with cystic fibrosis was effective in increasing relative weight and energy stores, but there was no evidence of any long-term functional benefit.

Blood Chemical Analysis↗
PubMed1983

Immediate and long-term effects of chest physiotherapy in patients with cystic fibrosis.

Both the immediate and long-term effects of chest physical therapy administered by a parent were evaluated in eight children with cystic fibrosis. Spirometric and plethysmographic evaluations were performed pre-CPT and at 5 and 30 minutes post-CPT. The pre-CPT measurements after a three-week period with no CPT were compared with the values while receiving CPT on a regular twice daily basis. There was a significant decrease after three weeks without CPT for FVC (P less than 0.025), FEV1 (P less than 0.005), FEF25-75 (P less than 0.005), and Vmax60TLC (P less than 0.025). When the patients had been receiving CPT on a regular basis, the only immediate effect was an increase in PEFR after 30 minutes post-CPT (P less than 0.05). After three weeks without CPT, there were increases at 30 minutes post-CPI for FVC (P less than 0.005) and Vmax60TLC (P less than 0.05). These findings indicate that although there may be little immediate functional improvement when CPT is received on a regular basis, a three-week period without CPT leads to a worsening of the functional status, which is reversed with renewal of regular CPT.

Adolescent↗
PubMed1983

An evaluation of rebreathing with the bain system during anaesthesia with spontaneous ventilation.

Data from 12 anaesthetized patients breathing spontaneously from the Bain system were used to calculate the degree of rebreathing occurring when the fresh gas flowrate (VF) was equal to 2, 1 and 0.7 times the estimated normal minute ventilation (Vtot). Measurements of the expired minute volume (VE) and end-tidal carbon dioxide tension (PE'CO2) were made to determine the effects of this rebreathing. No rebreathing occurred when VF was equal to twice Vtot. When VF was equal to Vtot rebreathing was usually small in amount and produced no changes in VE or PE'CO2. Changes attributable to rebreathing occurred in only two patients when VF was reduced to 0.7 Vtot. These results are explained by the presence of anaesthesia-induced ventilatory depression and favourable changes occurring in the respiratory wave forms in the majority of patients studied. In some patients, greater values of VE and rebreathing occurred in response to strong surgical stimulation. The net result of increased ventilation in these patients was a decrease in PE'CO2. It is concluded that during anaesthesia, when the Bain system is used with VF equal to Vtot, any increase in PE'CO2 which may result from rebreathing is likely to be small and seldom of clinical importance.

Adolescent↗
PubMed1983

Histamine inhalation challenge in children: a comparison of two methods.

Airway reactivity in children is often assessed using a histamine inhalation challenge test. The bronchoconstrictor agents are usually delivered by five slow inspiratory capacity (IC) maneuvers, the IC method. We compared the IC method with a tidal breathing (TB) method in 30 children; 11 were normal, six were under investigation for asthma and 13 were known asthmatics. None of the normal children responded to either method, whereas 18 out of the 19 (95%) known or suspected asthmatics responded to the TB method while only 13 out of 19 (68%) showed a significant reduction in FEV1 when the IC method was used. The concentration of histamine necessary to cause a 20% reduction in FEV1 was less for the TB method, suggesting that in children the TB method will produce airway reactivity more quickly than the IC method.

Adolescent↗
PubMed1982

Primary lung abscess in childhood: the long-term outcome of conservative management.

Fourteen cases of primary lung abscess in childhood were treated with antibiotics alone. The only organism discovered was Staphylococcus aureus. All the children recovered. Roentgenographic abnormalities took from six weeks to more than five years to resolve. Recently, follow-up of 11 of the 14 children was performed an average of nine years after treatment of the abscess. In all children, the clinical status, lung volumes, and expiratory flow rates were normal, except in two with asthma. A conservative approach to the management of primary lung abscess in children is recommended.

Adolescent↗
PubMed1982

Oxygen therapy and long-term pulmonary outcome of respiratory distress syndrome in newborns.

A previous report has shown no difference between the clinical outcome of infants exposed to a high oxygen (O2) regimen and those exposed to a low O2 regimen for the treatment of respiratory distress syndrome (RDS). Mechanical ventilation was not used in either group. In the present study, pulmonary function tests were performed on 14 survivors receiving the low O2 regimen (low O2 group) and on nine receiving the high O2 regimen (high O2 group) ten years after their initial illness. Similar evidence of abnormalities of large airways was found in both groups of prematurely born children that was comparable with that previously reported for normal prematurely born children. There was evidence in the high O2 group similar to that reported for ventilated survivors with RDS exposed to a high concentration of O2. From these data, it was concluded that neonatal exposure to high O2 concentrations in the absence of mechanical ventilation is capable of causing long-term change in small airways.

Airway Resistance↗
PubMed1982

Measurement of pleural pressure in neonates.

The indirect measurement of pleural pressure in neonates is obtained from measurements of esophageal pressure (Pes) with either a liquid-filled catheter or an esophageal balloon-catheter system. The purpose of this investigation was to assess the validity of the water-filled esophageal catheter by comparing the simultaneous changes in Pes and airway opening pressure (Pao) during occluded respiratory efforts. Equal changes in Pes and Pao under this condition indicate that Pes is a valid measurement of pleural pressure. In six healthy unsedated term neonates (aged 2-3 days) we measured Pes in the lower third of the esophagus with a water-filled catheter of eight French gage (FC), which has a 2-mm internal diameter. During occlusions, changes in Pes and Pao were almost identical in magnitude and timing in each body position studied (right lateral, prone, and supine). We conclude that the water-filled 8-FG esophageal catheter gives an accurate measurement of pleural pressure changes in healthy neonates.

Catheterization↗
PubMed1982

The effects of inspiratory muscle training in patients with cystic fibrosis.

This study evaluated whether inspiratory muscle training (IMT) could increase inspiratory muscle strength and endurance and exercise performance in 11 patients with cystic fibrosis (CF) with moderately severe airflow limitation. The IMT consisted of breathing through an inspiratory resistance (IR) for 15 min twice daily for 4 wk, preceded or followed by a 4-wk control period. After IMT, there was an increase in inspiratory muscle strength measured by maximal inspiratory mouth pressure at functional residual capacity: 74 +/- 18 cmH2O before training to 81 +/- 12 cmH2O after training, mean +/- 1 SD, p less than 0.025, and in inspiratory muscle endurance measured by the maximal IR tolerated for 10 min. Limitation of performance in the progressive exercise test was related to increased airflow limitation and possibly to poor nutrition. Mean exercise performance during progressive or submaximal exercise testing did not change after training. It is concluded that this form of IMT improved inspiratory muscle strength and endurance, but had little effect on exercise performance in patients with CF.

Adolescent↗
PubMed1982

The effect of digoxin on exercise capacity and exercising cardiac function in cystic fibrosis.

The ability of digoxin to increase exercise capacity and stroke volume (SV) during exercise was evaluated in ten patients with cystic fibrosis (CF) ages 12 to 20 years with moderate to severe degrees of airway obstruction but no history of heart failure. A double-blind crossover trial of digoxin versus placebo was carried out. An evaluation of exercise performance was undertaken upon entry into the study, and after each of the one-week periods in which digoxin 0.25 mg/day or placebo was taken. Exercise testing consisted of a progressive exercise test on a cycle ergometer to measure maximum work capacity (Wmax) and a steady state test at 2/3 of the baseline Wmax. During the steady state test, the oxygen consumption and carbon dioxide production were measured and cardiac output (Q) was calculated by the indirect Fick (CO2) method. From Q and heart rate (HR), SV was derived. After digoxin, Wmax was unchanged. On steady state exercise HR was unchanged, but there was a slight but significant fall in Q due to a fall in SV. The decrease in SV was associated with exercising hypoxemia. We conclude that digoxin did not increase exercise capacity or improve exercising cardiac function in patients with moderate to severe airway obstruction due to CF.

Adolescent↗
PubMed1981

Relationship between the chest radiograph, regional lung function studies, exercise tolerance, and clinical condition in cystic fibrosis.

This study evaluated the accuracy of the interpretation of the chest film in delineating localised abnormalities of ventilation and perfusion, as well as the overall severity of airways obstruction, exercise tolerance, and clinical condition in children with cystic fibrosis. Radiographic findings in various regions of the chest film were compared with the functional values obtained with regional lung function tests which evaluated the arrival and disappearance of boluses of radioactive nitrogen given by inhalation and infusion. While the more severely affected areas on the chest radiograph were found to correlate with similar regions on the lung function tests, as did overall scores, errors occurred in some cases if the x-ray film alone was used as a judge of regional physiological derangement. In addition the degree of airways obstruction, the exercise tolerance on a cycle ergometer, and clinical grading, each correlated significantly with the radiographic score. We conclude that the chest radiograph is a good indicator of the overall severity of the lung disease and that it correlates well with exercise tolerance and clinical condition in cystic fibrosis.

Adolescent↗
PubMed1981

Ventilation, respiratory center output, and contribution of the rib cage and abdominal components to ventilation during CO2 rebreathing in children with cystic fibrosis.

Although there has been extensive research into the control of breathing in adults with chronic obstructive lung diseases, there is little information in this area in children with cystic fibrosis (CF). The purpose of this study was to investigate the respiratory response of children with CF to CO2 under hyperoxic conditions. Using a standard CO2 rebreathing technique, we studied 14 children with CF. We evaluated their response to CO2 in terms of ventilation (VE), mean inspiratory flow rate (VT/TI), and the pressure generated at the mouth after 0.1 s of an inspiratory effort against an occlusion (P0.1). In order to understand the contributions of the rib cage and abdominal components to ventilation, we assessed the volume change in each compartment by attaching magnetometers to the chest and abdomen. Overall changes in lung volume were assessed in a volume displacement plethysmograph. We found that, when corrected for the height of the child, the slope of VE versus end tidal CO2 (PETCO2), as well as the slope of VT/TI versus PETCO2 correlated significantly with the degree of airway obstruction as expressed by the forced expiratory flow between 25 and 75% of vital capacity. The values for P0.1 were all within the normal range and showed no correlation with the degree of airway obstruction. The contribution of the rib cage and abdomen to ventilation during rebreathing was similar to that previously reported for adults. No changes were observed in functional residual capacity during rebreathing. We showed that tests involving a mechanical response to CO2 correlated with the degree of airway obstruction, but there was no evidence that the neuromuscular drive was abnormal.

Adolescent↗
PubMed1980

The role of nutritional status, airway obstruction, hypoxia, and abnormalities in serum lipid composition in limiting exercise tolerance in children with cystic fibrosis.

Previous work has shown that impaired exercise tolerance in children with cystic fibrosis (C.F.) is related to the severity of airway obstruction without elucidating the possible roles of hypoxia or malnutrition. It has been suggested that poor nutrition leads to abnormalities in serum fatty acids composition, which may lead to tissue hypoxia. We investigated the roles of hypoxia, pulmonary mechanics, nutritional status, and serum fatty acid composition in limiting exercise tolerance in C.F. In 20 children with C.F., exercise tolerance, while breathing air and while breathing oxygen, was evaluated on a cycle ergometer and compared to pulmonary function tests, anthropometric data, serum lipid compostition, and clinical condition. The mean percent work expected from height (Wmax) was 75, and was unchanged by O2. Wmax correlated significantly with the degree of respiratory impairement, the discrepancy between height and weight, and the clinical score but not serum fatty acid composition. Where measured, no child at any time had an elevated end tidal CO2(PetCO2). We conclude that nutritional status and airway obstruction are closely correlated with exercise tolerance in C.F. and that, unlike the case in adults with chronic obstructive pulmonary disease, exercise-limiting dyspnea occurs in the presence of a normal PetCO2.

Adolescent↗
PubMed1980

Upper airway obstruction in children. The value of inspiratory-expiratory flow-volume curves.

The physiological assessment of upper respiratory tract obstruction using inspiratory-expiratory flow-volume curves is a valuable non-invasive procedure in children. The technique employed at the Montreal Children's Hospital with appropriate case material is presented. Although flow-volume curves can reliably diagnose and localize a large airway obstruction, these lesions are readily monitored by spirometric testing.

Airway Obstruction↗
PubMed1978

Long-term pulmonary sequelae of the Wilson-Mikity syndrome.

Five children born prematurely, eight to ten years ago, who survived the Wilson-Mikity syndrome were compared with six apparently normal prematurely born children and eight normal children born at term, by means of flow volume curves obtained while breathing air and while breathing a mixture of 80% helium and 20% oxygen. The flow rates in air of the group who survived the Wilson-Mikity syndrome were significantly lower than those of the prematurely born normal children (P less than 0.01), and than those of the eight normal children (P less than 0.001). The volume of isoflow while breathing air compared to that while breathing HeO2 was highly variable, but not significantly different in the three groups. Three of the five survivors of the Wilson-Mikity syndrome had a marked concavity in the shape of their flow volume curves. It is concluded that these abnormalities are due to focal increases of compliance or resistances or both of terminal lung units and result in adjacent areas of the lung emptying at different rates. The relationship between physiologic and anatomic abnormalities seen at autopsy in those who die to the disease suggests that they are due to the same pathologic process. Whether or not these abnormalities will disappear with future lung growth remains to be seen.

Female↗
PubMed1977

Long-term pulmonary sequelae of premature birth with and without idiopathic respiratory distress syndrome.

Seven children born prematurely who survived the respiratory distress syndrome, seven children born prematurely who had no neonatal lung disease, and seven normal children born at term were studied by comparison of flow volume curves obtained while breathing air to those obtained while breathing 80% helium and 20% oxygen. Expiratory flow rates in air both groups of prematurely born children were lower than flow rates of the children born at term, and the volumes of iso-flow were higher in the survivors of RDS than those of the children born at term. The differences in flow rates in air suggest an increase in large airway resistance in both groups of prematurely born children. It is speculated that this may be secondary to growth retardation related to prematurity. The elevated Viso V in the RDS group suggests an increase in small airway resistance secondary to the disease or to its therapy.

Airway Resistance↗