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Biomedical subjects

C Mittman

Publications and source records attributed to C Mittman.

At least 19 recordsLinked to original sources
PubMed1993

A study on the lung function in alpha 1-antitrypsin-deficient (PiMZ) patients.

Laurel and Eriksson published the first report indicating that alpha 1-antitrypsin deficiency predisposed patients to the development of Chronic Obstructive Pulmonary Disease (COPD). For the purpose of early detection, disturbances of pulmonary function in alpha 1-antitrypsin mild deficiency cases (PiMZ) were compared with those of normal cases (PiMM) in caucasian Americans. The marked results are as follows. 1) Parameters of flow-volume curves were more disturbed in PiMZ cases than in PiMM cases. 2) Volumes of isoflow are specially different between PiMZ and PiMM cases. 3) Mechanical properties, like lung work of breathing, were larger in PiMZ cases than in PiMM cases.

Adult↗
PubMed1992

Reversibility of airways injury over a 12-month period following smoking cessation.

In this investigation, we examined changes in exfoliated tracheobronchial cells in sputum in 46 individuals (mean age = 49.2 years; mean packyears = 48.7) who discontinued smoking and 37 individuals (mean age = 54.9 years; mean packyears = 65.2) who continued to smoke over a 12-month period after participation in the St. Helena Hospital and Health Center one-week residential smoking cessation program. Before the beginning of the smoking cessation program, those who went on to quit were not different from those who did not quit with respect to baseline cytomorphology ratings. In those individuals with a minimum of three follow-up tests, results indicated significant reductions from precessation levels in macrophages, pigmented macrophages, and neutrophils after adjustment for differences in age, packyears, and pulmonary function (FEV1/FVC). Over the course of follow-up, quitters, in comparison with nonquitters, also had significantly lower mean levels of columnar cells, mucus, mucous spirals, and metaplasia. These results indicate a consistent effect of smoking cessation on cytomorphology and demonstrate that on cessation, some of the measured elements promptly return toward a more normal pattern.

Forced Expiratory Volume↗
PubMed1988

Bolus technique for assessing distribution of inspired gas during tidal breathing.

The washout of an insoluble tracer from the lung may be represented by a model with two ventilatory compartments representing poorly and better-ventilated regions. Using boli of a second insoluble gas delivered at a given point during inspirations of a multibreath washout test, the proportions of labeled inspired ventilation reaching the poorly and well-ventilated regions may be determined by analyzing the kinetics of the exhaled tracer. We studied eight normal subjects breathing through large-bore solenoid valves controlled to maintain tidal volume at 600 or 900 ml. Boli consisting of 15 ml of 80% He-20% O2 were delivered over 75 ms; this labeled approximately 125 ml of inspired gas. Boli were delivered after 50 ml had been inspired to mark early inspiration and after 300 ml had been inspired to mark midinspiration. Using 900-ml tidal breaths, late inspiration was marked by boli delivered at 600 ml. Subjects were studied in the seated and the supine positions. In both positions, significantly more of the early breath went to the poorly ventilated compartment. Several possible physiological mechanisms, singly or in combination, could account for these observations, but differences in dead space path length are most likely involved.

Adult↗
PubMed1986

Aging of the lungs: speculation on the role of oxidants and proteases.

In most regards, aging of the human lungs mimics the development of emphysema. Various lines of evidence suggest that oxidants and proteases play an important role in the pathogenesis of emphysema. The disease seems to arise through a complex interplay of genetic and environmental factors. This paper explores the possibility that normal aging of the lungs, as it has been defined by various cross-sectional and longitudinal studies, is part of a pathological continuum ending with frank emphysema. It is not clear if these are "normal" aging effects or the result of the accumulation of disease.

Aging↗
PubMed1985

A new pendant storage oxygen-conserving nasal cannula.

With increasing interest in reducing the cost of oxygen therapy, we recently designed an oxygen-conserving cannula. It reduces the oxygen supply flow necessary to achieve adequate oxygen saturation, but because it requires the use of a reservoir situated under the nose, some patients find it obtrusive. We therefore designed a similar system but displaced the reservoir away from the face and onto the anterior chest wall where it could be hidden from view by the patient's clothing. We evaluated this pendant conserving nasal cannula (PNC) in seven hypoxemic patients with chronic obstructive pulmonary disease. We compared oxygen saturations achieved using the PNC vs the standard steady flow nasal cannula (SNC) at 0.5 through 4 L/min. The mean improvement in oxygen saturation using the PNC vs the SNC was 3.3 percent at 0.5 L/min, 4.3 percent at 1 L/min and 3.1 percent at 2 L/min. These differences were statistically significant (p less than 0.001). The saturation achieved by the PNC at 0.5 L/min was equivalent to that achieved by the SNC at 1.8 L/min. We conclude that the PNC provides effective oxygen delivery to patients at supply flows substantially less than the SNC. The device is aesthetically acceptable to patients and its widespread use in patients requiring chronic oxygen therapy could bring about significant financial savings.

Adult↗
PubMed1984

Respiratory impairment in coke oven workers: relationship to work exposure and bronchial inflammation detected by sputum cytology.

Coke oven workers are at excess risk of developing lung cancer and may be at risk for chronic obstructive lung disease (COLD). We have studied 3799 male workers to assess the relationship between the two diseases. Repeated lung function and sputum cytology tests were obtained over a 3-year period. Sputum samples were assessed using standardized methods; in addition to metaplastic and neoplastic changes, we reproducibly assessed the presence and extent of acute and chronic inflammatory changes. Spirometric flow rates (FEV1) were significantly reduced in workers most exposed to coke oven emissions, particularly in those with excessive inflammatory cells and regular metaplasia in sputum. The presence of reactive bronchial epithelial cells and metaplasia were potent predictors of an abnormal FEV1/FVC. Studies like these may offer a means to investigate the relationship between COLD and lung cancer. Such changes in sputum may identify individuals at risk of developing both diseases.

Bronchi↗
PubMed1984

Factors affecting expired waveform for carbon monoxide.

We previously presented a method based on a computer lung model for determining the distribution of both specific ventilation and specific diffusing capacity. These argon and carbon monoxide (CO) washin and washout studies were obtained in 12 normal subjects and 24 patients with varying degrees of obstructive lung disease. In addition to end-tidal and mixed expired gas concentrations, the expired waveform for both gases was sampled. In patients we found that this method failed to adequately describe CO dynamics during the early part of expiration; predicted concentrations were higher than actual data. Modifications of the original model that satisfy all data are presented. This new model suggests that CO uptake occurs in spaces with ventilatory properties of dead space. The accuracy and reliability of these observations were established by computer simulation studies as well as by repeated testing in one subject. These proved to be highly reproducible over a period of 5 mo. Standard parameter sensitivity tests showed parameters to vary by less than 10% and to be stable even when realistic levels of noise were added to the data. We conclude that studies involving ventilation of insoluble gases are insufficient to describe gas exchange in the lung. The addition of an exchangeable gas adds significant understanding of lung function, particularly in disease.

Adult↗
PubMed1984

Collaborative study to assess risk of lung disease in Pi MZ phenotype subjects.

We studied 143 Pi MZ heterozygous (MZ) subjects from random populations that had been examined previously for alpha 1-antitrypsin phenotype. Each Pi MZ subject was closely matched with a Pi M control subject from the same population at each of 6 centers. An expanded National Heart, Lung and Blood Institute (NHLBI) respiratory symptom questionnaire was completed by each subject. Pulmonary function tests designed to detect established as well as early obstructive airway abnormalities were administered. Multivariate analysis of the variance of data from the questionnaire and pulmonary function tests corrected for age, race, sex, and smoking history showed no significant difference (p less than 0.05) between subjects of Pi MZ and Pi M phenotype. The size of the populations studied and number of observations made for each variable were sufficient to assure that small differences could be detected with 95% power. We conclude that MZ phenotype alone carries no greater risk of developing lung disease than M phenotype.

Adult↗
PubMed1984

Evaluation of a low-flow oxygen-conserving nasal cannula.

Oxygen therapy is one of the most frequently ordered therapies for patients with chronic obstructive pulmonary disease (COPD). In a large percentage of these cases, oxygen therapy is supplied via nasal cannula. With the rising cost of medical care and the search for more effective means of oxygen delivery, a new oxygen-conserving nasal cannula (CNC) that incorporates a closely coupled 20-ml reservoir was developed. Oxygen is stored in the reservoir during exhalation so that 20 ml of approximately 85% oxygen is the first gas inhaled. To test the hypothesis that the CNC is more efficient than the standard nasal cannula (SNC), 20 patients with COPD were evaluated. All patients were chronically hypoxemic at rest. Results indicate that when the CNC was compared with the SNC, arterial oxygen saturation levels were significantly different (p less than 0.001) at flow rates of 0.5, 1.0, and 2.0 L/min. Oxygen saturation were 2.9% higher at 0.5 L/min, 2.9% higher at 1 L/min, and 2.6% higher at 2 L/min for the CNC than for the SNC. In summary, the CNC offers a more efficient oxygen delivery system for those patients requiring supplemental oxygen administration by nasal cannula.

Aged↗
PubMed1982

Optimal inputs for parameter determination of inert gas washout from the lung.

The nitrogen washout test will yield more information about the distribution of pulmonary ventilation if a pattern of inspired gas concentrations is utilized other than the standard series of 100% oxygen breaths. The input breathing pattern which yields optimal results will vary with the specific features of the lung being studied but typically includes breaths of air, particularly in the last third of the washout. Using computerized, mathematical techniques, optimal inputs were selected for washout tests of duration 10, 20, 30 and 40 breaths for each of six lung models, ranging from a unicompartmental to a highly non-uniform 'diseased' lung. Knowing these optimal inputs we were able to devise a nominal input which was similar to the optimal inputs for all models. For a 10 breath test this nominal input pattern utilized a breath of air at breath 7. For a 20 breath test, air is utilized at breaths 12, 14, 15, 19; for 30, air at 19, 21, 22, 23, 29 and for a 40-breath test, air at breaths 19, 24, 28, 30, 31, 32 and 39. The 30-breath nominal sequence was compared with the conventional oxygen-only washout and a 31-breath pseudo-random binary (PRB) input. Comparisons were made using computer simulated washouts as well as actual tests on human subjects. The 30-breath nominal input was always superior to the standard washout and was superior to the PRB input for all models except the lung ventilated with vital capacity breaths. We conclude that a significant advantage is gained by substituting the recommended sequences of breaths in studies of the dynamics of gas exchange in the lung.

Humans↗
PubMed1981

Competitive inhibition of carbon monoxide transport: evidence against a carrier.

The existence of a saturable carbon monoxide (CO) carrier in the lung remains controversial. The carrier hypothesis was invoked to explain data that indicated that pulmonary diffusing capacity for CO (DLCO) decreases with increasing CO concentration. To test this hypothesis, we measured DLCO in 14 normal adult subjects at three alveolar CO concentrations (60, 660, and 2,060 ppm). Each mixture contained a constant amount of labeled C18O (60 ppm) and a balance of unlabeled C16O. If a saturable carrier exists at increasing CO concentrations, the unlabeled CO would compete for most of the sites on the carrier molecule, effectively inhibiting the uptake of the labeled C18O. C18O diffusing capacities (mean +/- SD) for the three levels of CO were 34.9 +/- 5.6, 33.0 +/- 6.0, and 34.7 +/- 7.8. There were no significant differences (P greater than 0.2) among the three levels. In another group of subjects we repeated the study using a gas mixture containing 130 ppm C18O. No significant differences were found. As a result, we find no evidence to support a CO carrier hypothesis.

Adolescent↗
PubMed1981

Distribution of ventilation and diffusing capacity in the normal and diseased lung.

Conventional tests of diffusing capacity (DL) consider the lung to be a uniform structure with regard to both ventilation and diffusion. These assumptions are incorrect even in normal subjects. We present a method for determining the distribution of both specific ventilation (SV) and DL from the washin and washout of C18O and simultaneous washout of argon. Both end-tidal and mixed-expired data are fit to a two-compartment lung model; parameters that define SV and DL are assigned to each compartment. From data generated by a model, the parameters recovered were found to be relatively insensitive to realistic levels of noise. Measurements in one subject were highly repeatable. We examined 15 normal subjects and 16 subjects with varying degrees of obstructive lung disease. In both groups the better ventilated spaces generally showed a higher DL. The sum of the total two-compartmental DL's correlated with, but was found to exceed, the value obtained using the steady-state method and generally exceeded the single-breath result. We conclude that this method has potential advantages over conventional methods and is worthy of further study.

Adolescent↗
PubMed1981

Risk factors for obstructive lung disease.

To assess the role of various risk factors in the pathogenesis of chronic obstructive lung disease (COLD), 163 men and women were followed for approximately 6 yr. Subjects were either community volunteers or relatives of patients with antitrypsin deficiency (PiZ or MZ phenotype). At the onset of the study no subject was receiving medical care for COLD. Covariance analysis revealed that expiratory airflow rates declined excessively in male subjects who had the PiMZ phenotype and reported a family history of lung disease. In subjects with the combination of characteristics, loss of lung function approximated that reported in subjects who have established COLD. In several such subjects, abnormalities have progressed so that they now require treatment. Changes in lung function were less striking in the presence of only 1 or 2 of the 3 risk factors studied. These findings demonstrated that the characteristics of the population being studied can influence the outcome of an investigation. This effect may help account fo the conflicting results of previous investigations designed to assess the role of the PiMZ phenotype in the pathogenesis of COLD.

Adult↗