Zab Mohsenifar

Pulmonary Physiologic Changes of Morbid Obesity

OBJECTIVE Our objective was to study the effects of extreme obesity on pulmonary function tests and the effects of smoking on these variables in a population group larger than has previously been reported. DESIGN Retrospective data analysis. SETTING Academic medical center. PATIENTS Forty-three patients with extreme obesity [ratio of weight in kilograms to height in centimeters greater than 0.9 (W/H)] who underwent pulmonary function testing at Cedars-Sinai on an out-patient or in-patient basis during the period of 1979 to 1 997. MEASUREMENTS AND RESULTS Patients underwent standard pulmonary function testing. The patients were divided into 2 groups based on the W/H ratio: group A (0.9-0.99) and group B (greater than 1.0). Chart review was performed to identify pertinent history/co-morbidities. The independent effects of smoking between each groups patients were assessed. Forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), expiratory reserve volume (ERV), functional residual capacity (FRC), maximum voluntary ventilation (MVV), and forced expiratory flow during midexpiratory phase (FEF25-75%,) were significantly reduced in both groups. Single-breath diffusing capacity for carbon monoxide (DLCO) and the volume of gas into which the single-breath of carbon monoxide and helium was diluted were not elevated. Smoking did not account for the results in group A but did seem to partially explain the decrease in FVC, FEV1, and FEF25-75% in group B. CONCLUSIONS Extreme obesity is associated with a reduction in ERV, FVC, FEV1, FRC, FEF25-75%, and MVV. However, contrary to prior reports, D(LCO) is not elevated. These effects are only partially explained by smoking.

Computed tomographic-based quantification of emphysema and correlation to pulmonary function and mechanics.

Computed tomographic based indices of emphysematous lung destruction may highlight differences in disease pathogenesis and further enable the classification of subjects with Chronic Obstructive Pulmonary Disease. While there are multiple techniques that can be utilized for such radiographic analysis, there is very little published information comparing the performance of these methods in a clinical case series. Our objective was to examine several quantitative and semi-quantitative methods for the assessment of the burden of emphysema apparent on computed tomographic scans and compare their ability to predict lung mechanics and function. Automated densitometric analysis was performed on 1094 computed tomographic scans collected upon enrollment into the National Emphysema Treatment Trial. Trained radiologists performed an additional visual grading of emphysema on high resolution CT scans. Full pulmonary function test results were available for correlation, with a subset of subjects having additional measurements of lung static recoil. There was a wide range of emphysematous lung destruction apparent on the CT scans and univariate correlations to measures of lung function were of modest strength. No single method of CT scan analysis clearly outperformed the rest of the group. Quantification of the burden of emphysematous lung destruction apparent on CT scan is a weak predictor of lung function and mechanics in severe COPD with no uniformly superior method found to perform this analysis. The CT based quantification of emphysema may augment pulmonary function testing in the characterization of COPD by providing complementary phenotypic information.

Inhaled or Intravenous Pentamidine Therapy for Pneumocystis carinii Pneumonia in AIDS: A Randomized Trial

OBJECTIVE To compare inhaled pentamidine with intravenous pentamidine for the treatment of Pneumocystis carinii pneumonia in the acquired immunodeficiency syndrome (AIDS). DESIGN A randomized trial. SETTING Community teaching hospital and hospital-based outpatient treatment center. PATIENTS Twenty-one homosexual men with pneumocystis pneumonia; 11 received inhaled pentamidine and 10 received intravenous pentamidine. INTERVENTION Inhaled (8 mg/kg body weight) or intravenous (4 mg/kg body weight) pentamidine administered daily for 21 days. MEASUREMENTS AND MAIN RESULTS All patients responded to intravenous pentamidine, whereas 6 of 11 (55%; 95% CI, 23% to 83%; P = 0.02, Fisher exact test) responded to inhaled pentamidine therapy. Two patients who failed inhaled pentamidine therapy eventually died despite appropriate intravenous therapy (mortality rate, 18%; CI, -6% to 42%). Nonresponders to inhaled pentamidine had a greater severity of illness compared with responders to this therapy, as shown by a lower mean (+/- SE) Pao2 (8.0 +/- 0.4 kPa compared with 10.8 +/- 0.6 kPa; P = 0.005) and higher alveolararterial Po2 difference (6.8 +/- 0.6 kPa compared with 2.8 +/- 0.8 kPa; P = 0.003). CONCLUSIONS Inhaled pentamidine is probably as effective as intravenous pentamidine in patients with mild pneumocystis pneumonia. However, its use as sole therapy in patients with moderate to severe pneumocystis pneumonia is not supported by the results of our study and is not warranted.

Diagnostic value of fiberoptic bronchoscopy in metastatic pulmonary tumors.

The fiberoptic bronchoscopic procedure (with brushings, washings, and biopsies) was performed and specimens of sputum were obtained before the procedure in 37 patients with cancer metastatic to the lung. Of the 37 patients studied, endobronchial lesions were visualized at bronchoscopic examination in 14 (group 1), and no endobronchial lesion was seen in 23 (group 2). The yield of bronchial brushing and washings was not significantly different in group 1 and 2, whereas examination of sputum obtained before the bronchoscopic procedure and bronchial biopsy in group 1 yielded higher results than the same procedures in group 2. The radiographic findings did not influence the yield with any of the bronchoscopic procedures. The overall positive diagnostic yield from fiberoptic bronchoscopic procedures among these patients was 54 percent (20/37), regardless of their bronchoscopic or radiologic findings.

The effect of abnormal levels of hematocrit on the single breath diffusing capacity

In order to study the effect of different levels of hematocrit on the single breath diffusing capacity (DLCO), we studied 90 lifelong nonsmokers with either iron deficiency anemia, polycythemia vera or normal hematocrits, age range 9 to 81 years, with expiratory normal flow rates and lung volumes. The DLCO ranged from 10.6 to 41.3 ml/min/mmHg and hematocrit ranged from 28%–64%. We noted a significant relationship between the DLCO and age, height, and hematocrit. We recommend that DLCO measured in the conventional manner be corrected for anemia and polycythemia by incrementing or decrementing the measured value, if expressed as a percent of predicted, by 1.35% for each percent of measured hematocrit below or above the normal values of 44%.

Role of exercise testing in assessing functional respiratory impairment due to asbestos exposure.

To evaluate the complaint of exertional dyspnea in asbestos-exposed shipyard workers, pulmonary function tests were performed at rest and during exercise on 90 subjects with pleural plaques. We divided the subjects into four groups based on resting pulmonary function studies. Group I subjects (eight) had a restrictive defect; group II subjects (30) had an obstructive defect; group III subjects (six) had an isolated reduction in diffusing capacity; and group IV subjects (46) had a normal study. Subjects with a restrictive defect demonstrated minor physiologic abnormalities during exercise. Subjects with an obstructive defect demonstrated abnormalities consistent with their obstructive defect. Subjects in groups III and IV demonstrated an abnormally elevated wasted ventilation fraction, which may be an early indicator of interstitial disease due to asbestos exposure. We believe exercise testing was a useful tool in excluding the presence of significant functional exercise limitation due to asbestos exposure in the majority of subjects and also in disclosing some physiologic abnormalities in some of the subjects in our study.

Lymphocytic pleural effusion in postpericardiotomy syndrome

Postpericardiotomy syndrome has been recognized as a frequent complication following coronary artery bypass graft (CABG) surgery. We observed five cases of postpericardiotomy syndrome resulting in exudative pleural effusions with white blood cell differential counts greater than 80% lymphocytes. Tuberculosis, lymphoma, and other neoplasma have been major diseases associated with lymphocytic exudative pleural effusions. We feel postpericardiotomy syndrome is another important etiology that should be considered in post-CABG patients with lymphocytic pleural effusion.

Regional distribution of lung perfusion and ventilation in patients with chronic congestive heart failure and its relationship to cardiopulmonary hemodynamics

To study the relationship between the distribution of pulmonary blood flow, pulmonary ventilation, and pulmonary capillary wedge pressure, we studied six patients with chronic congestive heart failure (CHF) (New York Heart Association classes II and III) at rest and during exercise. We used krypton 81m (81mKr) and technetium 99m (99mTc) to assess lung ventilation and perfusion at rest and during exercise. Hemodynamic measurements were obtained with a balloon floatation thermodilution catheter. At rest, the upper lung zones of patients with CHF received significantly higher proportions of the blood flow compared with previously published data in normal volunteers. During exercise, however, the fractional perfusion to apices did not change, which suggests that apical flow redistribution is already maximized at rest. Measured pulmonary capillary wedge pressure failed to correlate with the upper zone or the ratio of upper-to-lower zone perfusion counts. Our findings suggest that upper zone flow redistribution may be associated with high, normal, or low capillary wedge pressure and therefore does not correlate with the pulmonary capillary wedge pressure in patients with chronic CHF.

Asbestos and airflow limitation.

To assess the effect of asbestos on the airways, researchers studied 45 shipyard workers who were lifelong nonsmokers and had asbestos-related abnormalities seen on their chest roentgenograms. Patients with interstitial lung disease, bronchial asthma prior to asbestos exposure, recurrent pneumonias, or significant cardiovascular disease were excluded from the study. In addition to chest films, they had spirometry performed before and after bronchodilator inhalation, lung volumes, diffusing capacity, and arterial blood gases. Forced vital capacity and forced expired volume in one second were normal in all patients. Maximum midexpiratory flow rates (MMFR) were abnormal (MMFR less than 75% of predicted) in 13 patients (29%). Therefore, 29% of lifetime nonsmokers with asbestos exposure exhibited evidence of small airways dysfunction. An abnormal MMFR in these workers may be due, in part, to asbestos exposure and could conceivably indicate a population at risk for pulmonary fibrosis and/or obstructive airways disease.

Effect of Breathing Pattern on Dead Space Ventilation VD/VT during Exercise

In order to assess the effect of breathing pattern on measurements of dead space ventilation (VD/VT) during exercise, we studied 6 patients with the complaint of exertional dyspnea. They had essentially normal resting pulmonary function studies and the only abnormality noted during an initial exercise study was an elevated VD/VT associated with a rapid respiratory rate. A second exercise study was then performed during which they were coached to breathe at a slower rate and larger tidal volume. During the exercise study with coaching, the VD/VT response was normal. We conclude that breathing pattern during exercise influences VD/VT and that an increase in total minute ventilation which is accomplished by a preferential increase in respiratory rate may result in an abnormally high VD/VT.