Biomedical subjects

J A Leech

Publications and source records attributed to J A Leech.

25 records · Page 2Linked to original sources

PubMed1985

Diffusing capacity for carbon monoxide. The effects of different derivations of breathhold time and alveolar volume and of carbon monoxide back pressure on calculated results.

The effect of deriving breathhold time and alveolar volume in different ways and of subtracting the back pressure of carbon monoxide on the calculated diffusing capacity (DLCO) was examined in 398 young adult smokers, ex-smokers, and nonsmokers. Significantly higher values were obtained when the recommendations of the ATS-DLD Epidemiology Standardization Project were followed for calculating breathhold time and alveolar volume, respectively, compared to following those of the ECCS Standardized Lung Function Testing Project. We therefore recommend that in reporting DLCO results, an explicit statement be included on the methods used to calculate both. Significantly higher values for DLCO were also obtained when CO back pressure was taken into account. The magnitude of this effect in smokers makes it difficult not to recommend its inclusion in epidemiologic studies. In clinical laboratories, however, when correction for CO back pressure is omitted, it is unlikely to result in an underestimate of DLCO of more than 5%, even in smokers.

Adult↗

PubMed1985

Relationship between pulmonary function and sleep-induced respiratory abnormalities.

The relationships between pulmonary function and sleep-induced respiratory events were studied in 34 consecutive male patients with suspected sleep apnea syndrome. In view of the effects of obstructive airway disease on pulmonary volume and airway resistance (Raw), patients were divided into two groups, those with and those without obstructive airway disease. Percent predicted functional residual capacity (FRC) correlated significantly with the apnea-plus-hypopnea index (AHI) in patients with and without obstructive airway disease (r = -0.62 and p less than 0.01; and r = -0.57 and p less than 0.01, respectively) whereas percent predicted total lung capacity had a significant relationship with AHI only in patients with obstructive airway disease (r = -0.80; p less than 0.001). In patients without such disease, a significant correlation between inspiratory airway conductance (Gaw) and AHI (r = -0.47; p less than 0.05) was also present, while percent predicted FRC and Gaw did not correlate with normalized weight. These findings suggest that decreased pulmonary volume and increased Raw contribute to the severity of sleep-induced respiratory abnormalities in patients with sleep apnea syndrome regardless of the degree of obesity.

Adolescent↗

PubMed1984

Short-course chemotherapy for mycobacteriosis kansasii?

The success of short-course chemotherapy for tuberculosis, the similarity between Mycobacterium tuberculosis and M. kansasii and the effectiveness of rifampin against the latter organism prompted a comparison of the diseases due to these organisms to assess the feasibility of a prospective trial of short-course chemotherapy in patients with mycobacteriosis kansasii. The two groups of patients were matched for age, sex and time of diagnosis. The patients with mycobacteriosis kansasii more frequently had underlying obstructive pulmonary disease. The clinical course of mycobacteriosis kansasii was more indolent, with a slower rate of improvement according to the chest x-ray films and a longer time before sputum smears and cultures became negative. M. kansasii was significantly more resistant to all the antibiotics, including rifampin. Although these differences from tuberculosis suggest that an equally short course of therapy may not be effective for patients with mycobacteriosis kansasii, the outcome was good in compliant patients who were given the three most effective major drugs for 12 months after the sputum smears and cultures had become negative. Therefore, a trial of modified short-course chemotherapy is recommended for patients with mycobacteriosis kansasii.

Clinical Trials as Topic↗

PubMed1984

Pulmonary toxicity of amiodarone.

Mild pleuroparenchymal fibrosis associated with amiodarone pulmonary toxicity is reported in a 63-year-old white man; partial radiographic resolution and complete symptomatic resolution with decreasing the daily dosage to 200 mg permitted continued anti arrhythmic therapy.

Amiodarone↗

PubMed1983

Respiratory pressures and function in young adults.

The relationships of lung functions to maximal respiratory pressure relative to the role of other recognized determinants (height, weight, age, and smoking status) were examined in 924 healthy Caucasian urban residents, 369 males 15 to 35 yr of age and 555 females 13 to 35 yr of age. In subjects no longer thought to be growing in stature, height was the main determinant of most functions. After height, respiratory pressures were the main determinant of forced vital capacity (FVC), forced expiratory volume in one second (FEV), and peak flow in men and women, with weight also an important determinant in women. Age had no consistent effect, and, although functions in smokers were lower than in nonsmokers for several tests, the effects were only significant for FEV and forced expiratory flow during the middle half of the FVC in women. These findings indicate that, if required, between-subject variation in this age group can be reduced by taking into account the relatively simple measurement of maximal inspiratory and expiratory pressures.

Adolescent↗

PubMed1981

Superior vena caval obstruction. Is it a medical emergency?

With the question in mind is superior vena caval obstruction a medical emergency, we reviewed 107 cases of superior vena caval obstruction in adult patients. We sought details of the time duration between the onset of symptoms and the treatment, and examined the complication and survival of patients with this disorder. Fifteen percent of the cases developed from benign causes. In 41 percent there was a previously recognized disease as the etiology. Benign disorders required longer to make the diagnosis. No serious complication resulted from the superior vena caval obstruction itself nor investigative procedures leading to the diagnosis despite, in some cases, a prolonged period between the onset of symptoms and the initiation of therapy. Prognosis and response to treatment were dependent on the underlying cause of the superior vena caval obstruction. Although several cases of tracheal obstruction were included in this series, we did not address the question of whether tracheal obstruction is or is not a medical emergency. No support was found for the notion that superior vena caval obstruction in itself represents a radiotherapeutic emergency.

Adult↗

PubMedDate not supplied

Environmental tobacco smoke exposure patterns: a subanalysis of the Canadian Human Time-Activity Pattern Survey.

This subanalysis of the Canadian Human Activity Pattern Survey examines environmental tobacco smoke (ETS) exposure in non-smoking respondents relative to age, sex, socioeconomic status and prevalence of asthma. 2,381 respondents (response rate 64.5%) from Toronto, Vancouver, Edmonton and Saint John completed a 24-hour recall time-activity diary. For each activity and location, respondents were asked, "was there any smoking during the activity?" Among non-smoking adults, youth, children and asthmatics, the rates of ETS exposure were 32%, 34%, 30% and 42% respectively. Regarding the location of exposure, adults reported ETS exposure in various locations (work, bars and restaurants), including home. Children experienced the most exposure at home, primarily between 4 p.m. and midnight. Adults reported ETS mainly in the living room (16%) and vehicles (13%); for children, the living room (22%) and the bedroom (13%) were the most common locations. Determining characteristic time and location patterns for ETS exposure underpins educational strategies to help non-smokers avoid ETS exposure.

Adolescent↗