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Biomedical subjects

P H Beaudry

Publications and source records attributed to P H Beaudry.

At least 37 records · Page 2Linked to original sources

Late effect of nocturnal mist tent therapy related to the severity of airway obstruction in children with cystic fibrosis.

To evaluate the long-term effect of nocturnal mist tent therapy on the progression of airway obstruction in children with cystic fibrosis (CF) of varying severity, two matched groups each consisting of 24 children with CF were studied during 18 months on mist tent therapy and 18 months of therapy. The progression in airway obstruction was measured by change in serial measurements of maximal midexpiratory flow (MMEF), from which a regression equation of MMEF against time was obtained for each individual. Changes in MMEF value with or without therapy were compared in patients matched for severity of disease as indicated by initial MMEF values. For the group as a whole no differences were found in the progression of the airway obstruction whether the patients received mist tent therapy or not. This therapy failed to benefit any of the groups of children with CF who had early, moderate, or advanced airway obstruction as judged from their initial MMEF value. It is concluded that nocturnal mist tent therapy neither decreases airway obstruction nor prevents its progression in children with CF.

Adolescent↗

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↗

Treatment of laryngotracheobronchitis (croup). Use of intermittent positive-pressure breathing and racemic epinephrine.

Use of racemic epinephrine hydrochloride (Vaponefrin), delivered by intermittent positive-pressure breathing, in the treatment of laryngotracheobronchitis (croup) produced acute beneficial results in a controlled study. However, symptoms often recurred within two hours, suggesting that this form of treatment should not be used in the emergency room and the patient then sent home. This treatment had no effect on arterial oxygen gas pressure. The changes in clinical status 24 to 36 hours after admission into the study were similar for the patients in the treatment and control groups, suggesting that the natural history of the disease was not drastically altered by this form of treatment.

Acute Disease↗

Early versus late introduction of continuous negative pressure in the management of the idiopathic respiratory distress syndrome.

To evaluate the effectiveness of the early application of continuous negative pressure about the thorax, 23 infants with the idiopathic respiratory distress syndrome who had adequate alveolar ventilation were assigned to early or late application of CNP. There were 11 infants in the early CNP and 12 in the late CNP group. There were no differences between the two groups with respect to birth weight, gestational age, age at admission to the study, initial FIO2 requirements, or initial PaO2, PaCo2, and AaPO2. None of the ENCP patients required mechanical ventilation, whereas four of the LCNP group did so. The FIO2 requirements were significantly less for the ECNP infants when compared to the LCNP ones. The mean duration of FIO2 requirements greater than 0.6 was 28.3 hours for those receiving ECNP and 60.7 hours for those in LCNP (P LESS THAN 0.05). This study suggests that the course of RDS may be modified by the early application of CNP.

Carbon Dioxide↗

The effect of age on arterial--alveolar nitrogen difference in normal adults.

The arterio--alveolar nitrogen difference (aADN2) has been associated in 27 normal adult subjects aged 20--60 years. As it may be assumed that venous and arterial PN2 are identical, we have used a sample of venous blood. There is a significant positive correlation between aADN2 and age. As the increase of aADN2 with age resembles that found in the literature for AaDO2, we concluded that the latter may be explained by increasing VA/Qc inequality within the lung.

Adult↗

Effect of positive-pressure breathing on aADN2 in hyaline membrane disease.

In seven subjects with hyaline membrane disease and breathing 40-70% oxygen in nitrogen, the effect of continuous positive-pressure breathing (CPPB) was examined by application of a continuous negative pressure (10 cm water) about the thorax and assessment of the alveolar-arterial tension differences for nitrogen (aADn2) and oxygen (AaDo2). On CPPB, there was a decrease in the aADn2 by a mean 9 mmHg and a decrease in the AaDo2 by a mean 44 mmHg. This corresponded to a decrease in the total venous admixture (Qva/Qt) of 0.20 and to a decrease in the venous admixture due to a true right-to-left shunt (Qs/Qt) of 0.19. These data were interpreted to mean a significant improvement in Va/Qc imbalance within open ventilated parts of the lung, which could be responsible, particularly by relief of local alveolar hypoxia, for reduction of the pulmonary vascular resistance and the true right-to-left shunt.

Carbon Dioxide↗

Contribution of inhomogeneity of lung units to the maximal expiratory flow-volume curve in children with asthma and cystic fibrosis.

Normal children as well as those with asthma and cystic fibrosis were studied to assess the contribution of lung zones emptying at different rates to the curvilinearity of the maximal expiratory flow-volume curve. Lung volumes, maximal expiratory flow-volume curves breathing air and then breathing a helium-oxygen mixture, and single-breath nitrogen washouts were measured. Forced expiratory maneuvers from lung volumes near functional residual capacity were performed to produce transients of flow exceeding maximal flow defined by the full flow-volume curve. Normal children and those with asthma and mild cystic fibrosis had small or no transients. Those with severe cystic fibrosis had large transients as well as increased phase I on the nitrogen washout curves. These large transients were associated with increased curvilinearity of the maximal expiratory flow-volume curve and smaller than normal flow response breathing helium. In severe cystic fibrosis, the large transients suggest sequential emptying of fast and slow spaces, which influences the shape of the maximal expiratory flow-volume curve. The fast space could be due to compression of an enlarged anatomic dead space. Any time constant inequality between parenchymal units present in asthma and mild cystic fibrosis does not appear to contribute significantly tof the shape of the maximal expiratory flow-volume curve.

Adolescent↗

The timing of tuberculin tests in relation to immunization with live viral vaccines.

The validity of the recommendation that routine screening for tuberculosis precede the administration of live viral vaccines was tested in a field study. One hundred and ten children already known to be tuberculin-positive, mostly on the basis of prior vaccination with BCG, were immunized with live viral vaccine and retested with tuberculin at the same time. Reversion to a negative tine test occurred in 3% of children given measles, mumps, or rubella vaccine, and 3.6% of controls who received no vaccine but had the tuberculin test repeated at the same interval. Very few Mantoux reactions (two of 68) reverted to negative in children given one of the three vaccines, singly or in combination; some became smaller, but there was no significant difference in the changes in the size of the Mantoux reaction between the vaccinated group and the control group, with the exception of an unexplained increase in the size of the reaction in many of those who received rubella vaccine. Screening for tuberculosis by tine or Mantoux test is not invalidated by simultaneous administration of vaccines against measles, mumps, or rubella, given singly or in combination, as part of preventive care programs.

Adolescent↗

Prevalence of mycobacterial sensitivity in Montreal children.

The prevalence of sensitivity to atypical mycobacteria was found to be low in 2152 Montreal first-grade children tested with tuberculin and one of four atypical antigens randomly allocated. Forty-nine had positive reactions to an atypical antigen. PPD-G produced more reactions than PPD-A, -B or -K. In Greater Montreal there was a higher prevalence of sensitivity to atypical mycobacteria than in the two suburban areas studied. The range of this prevalence, standardized for the type of antigen, was from 0.86 to 2.92% according to region. The highest prevalence of sensitivity to any single atypical antigen, 5.3%, was found for PPD-G in Greater Montreal.Tuberculous infection was found in 1.35% of the children. Small tuberculin reactions (5 to 9 mm to stabilized PPD 5 TU) require clarification by differential tuberculin testing. More of them are caused by M. tuberculosis than by atypical mycobacteria in this particular age group and region.Routine BCG immunization is not indicated for the particular population studied; when given to individuals at risk, its effectiveness should not be impaired by atypical sensitivity at the low level found locally. Future BCG plans require more epidemiologic data.

Child↗

Preventive treatment of tuberculin-negative contacts.

Five children who had been in close contact with highly infectious tuberculous individuals presented recently to the tuberculosis service of The Montreal Children's Hospital. Four had developed serious pulmonary tuberculosis and one tuberculous meningitis, all within the three months which followed a post-contact negative tuberculin test.The management of tuberculin-negative children recently exposed to active infectious tuberculosis by repeated skin tests and chest radiography alone is inadequate for their protection. These children are at high risk of developing disease by the time their tuberculin sensitivity has become evident. It is inadvisable to vaccinate them with BCG until three months after their last exposure to the disease. A plea is made for preventive chemotherapy in these cases.

Aminosalicylic Acids↗

Response to disodium cromoglycate in children with chronic asthma.

Twenty-three children with chronic severe perennial asthma received randomly-allocated disodium cromoglycate or placebo four times a day for 12 weeks, and the alternative regimen for the subsequent 12 weeks. More than half the patients improved while on DSCG according to clinical assessment. There was a significant increase in the mean FEV(0.75 second) during the drug period, largely owing to dramatic improvement in nine patients. No reduction in the mean decrease of FEV after exercise was demonstrated. Response, when it occurred, was evident within four weeks. The effect of the medication was consistent in individual patients throughout the 12-week period. No evidence of toxicity was discovered during the period of study.

Adolescent↗