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Biomedical subjects

R M Cherniack

Publications and source records attributed to R M Cherniack.

At least 91 records · Page 5Linked to original sources
PubMed1976

Computer analysis of the single-breath nitrogen washout curve.

A computerized system has been developed to analyze the parameters that can be derived from the nitrogen washout curve. Analog signals for air flow, volume, and nitrogen concentration are entered either on-line or off-line into a 24,000 mini-computer. The program calculates vital capacity, total lung capacity, and residual volume, as well as the slope of phase III, closing volume in liters, total lung capacity, residual volume, closing capacity, closing volume/vital capacity ratio, and closing capacity/total lung capacity ratio. Validation tests showed excellent correlation between hand- and computer-calculated values of closing volume(r=0.864), vital capacity (r=0.997), total lung capacity (r=0.991), and slope of phase III (R=0.926). We concluded that the computerized system for analysis of the expired nitrogen washout curve is as reliable as hand calculations and is immeasurably faster.

Diagnosis, Computer-Assisted↗
PubMed1976

Long-term use of intermittent positive-pressure breathing (IPPB) in chronic obstructive pulmonary disease.

The long-term use of intermittent positive-pressure breathing (IPPB) to deliver bronchodilator was compared to delivery by air compressor in 88 patients with chronic obstructive pulmonary disease who were in the home care program. There was no difference between the two groups in terms of number of hospital admissions, days spent in hospital, or mortality. The deterioration in ventilatory function was the same in both groups, althouth the patients receiving IPPB appeared to have developed greater hyperinflation. The data suggest that there is little evidence to support the long-term use of IPPB in the therapy of most patients with chronic obstructive pulmonary disease.

Aerosols↗
PubMed1976

Effect of modification of the smoking habit on lung function.

The effect of smoking cessation or modification on lung function was determined during a 48-week period. In a large number of the cigarette smokers, a disturbance of lung function was not revealed by conventional tests, such as the 1-sec forced expiratory volume; however, an abnormality was often demonstrable in tests that may reflect alterations in small airways, such as closing volume and Phase III of the single-breath expired N2 curve. There was no relation between the degree of abnormality of lung function and the presence of respiratory symptoms, but there appeared to be a relationship to lifetime smoking history, the heaviest smokers having the poorest function. Cessation, or more than 25 per cent decrease in the number of cigarettes smoked, was attened by improvement in the slope of Phase III of the N2 washout curve, closing volume, and closing capacity, as well as forced vital capacity, 1-sec forced expiratory volume, and peak flow. Resumption of smoking after cessation was attended by a deterioration in the slope of Phase III and closing capacity. The data suggest that the functional abnormalities in smokers are related to smoking and are at least partially reversible by cessation or significant modification of the smoking habit.

Adolescent↗
PubMed1976

The effect of lung volume on the ventilatory response to CO2 during resistive loading in normal subjects.

The ventilatory response to CO2 during resistive loading was determined in normal subjects when the end-expiratory level was allowed to increase and when it was restored to that present in the unloaded state. Restoration of the end-expiratory level of that seen in the unloaded state, during the resistive loading, resulted in an increase in ventilatory response to CO2. The mechanism by which increases in lung volume affect the ventilatory response to CO2 is unknown; multiple factors are likely to be involved. It is suggested that an increase in end-expiratory level plays a major role in limiting the ventilatory response to CO2 during resistive loading and may also be an important factor in the reduced ventilatory response to CO2 that is seen clinically when there is obstruction to air flow.

Adult↗
PubMed1975

Effect of gas density on dynamic pulmonary compliance.

We measured dynamic pulmonary compliance (Cdyn( in nine asymptomatic young men breathing gases of different density. When corrected for gas inertia, Cdyn was significantly lower during dense gas breathing (sulfur hexafluoride) than during air breathing. At higher breathing frequencies (60-90 breaths/min), Cdyn was greater on helium than on air. Static compliance was not different while breathing the three gas mixtures. These results may be explained by a density dependence of airways resistance in parallel lung units which contribute to frequency dependence of dynamic compliance. We conclude that most frequency-dependent behavior occurs among intraregional lung units subtended from airways between segmental bronchi and peripheral airways.

Adult↗
PubMed1975

Learning pulmonary function interpretation: deductive versus inductive methods.

Volunteer undergraduate medical students were randomly divided into 2 groups. One group were given pulmonary function data and the correct diagnoses from 18 patients. They were told to try to derive the rules by which the diagnoses were made. The other group were given the data from the same 18 patients, but were required to use a computer-assisted instructional program to arrive at the diagnoses in a deductive fashion. Both groups were pre- and post-tested. The deductive method provided higher post-test results. The inductive method took longer and produced more dropouts from the study.

Analysis of Variance↗
PubMed1975

Intraindividual variability in maximal expiratory flow-volume and closing volume in asymptomatic subjects.

The variability of the parameters derived from analysis of the forced vital capacity and the expired nitrogen trace after a vital capacity inhalation of oxygen (closing volume) within a day, from day to day, and from week to week, has been determined. Effort-dependent tests as vital capacity and peak expiratory flow showed the least variability. The greatest variability was seen in effort-independent tests of function such as the maximal expiratory flow rate at 25 per cent (75 per cent of expired vital capacity) and 50 per cent of vital capacity, as well as closing volume. The degree of variability in the tests used was uninfluenced by the periodicity of the tests or the age or smoking habits of the subjects tested. It is suggested that variability of tests of respiratory function should be taken into account in their interpretation.

Adolescent↗
PubMed1972

North American blastomycosis in Central Canada. A review of 36 cases.

Experience with 36 cases of North American blastomycosis in Central Canada is reported. Symptoms referable to the respiratory tract predominated, but no uniform clinical pattern for the disease process was evident. Cutaneous and genitourinary tract involvement was present in only a small proportion of patients. The majority of the patients resided in rural areas or were associated with some form of outdoor occupation or activity. No characteristic radiologic appearance could be identified in this series. Amphotericin B administered intravenously is the treatment of choice for this condition. North American blastomycosis is more widespread on this continent than has been previously demonstrated.

Adolescent↗