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Biomedical subjects

R T Abboud

Publications and source records attributed to R T Abboud.

At least 19 recordsLinked to original sources
PubMed1992

The effect of postural drainage positioning on ventilation homogeneity in healthy subjects.

Body position is known to have significant effects on oxygen transport. These effects, however, are seldom considered during postural drainage (PD). The purpose of this study was to examine the effect of modified PD positions on ventilation homogeneity (the evenness of the distribution of ventilation), which is a key component of oxygen transport. The single-breath nitrogen washout test was used to obtain an index of ventilation homogeneity (slope of phase 3 [SBN2/L%]). Seventeen healthy individuals, ranging from 22 to 40 years of age ( mean = 28.4, SD = 5.6), performed the single-breath nitrogen test while sitting, lying supine with the bed tipped head down, right side lying, and right side lying with the bed tipped head down. Within-subject one-way analyses of variance and Tukey's post hoc analyses were used to compare differences in SBN2/L% across the four positions. The distribution of ventilation was significantly less homogeneous in the side-lying positions compared with the supine and sitting positions. Although these results reflect a position-induced change in pleural pressure gradient, they also reflect the effect of gravity-independent, intraregional changes on ventilation distribution. Thus, modified PD positioning has a significant effect on ventilation homogeneity, which may predispose a patient to arterial desaturation. Given the complexity of the factors involved, patients considered for PD positioning should be monitored for arterial saturation.

Adult↗
PubMed1992

Acute effect of cigarette smoking on the carbon monoxide diffusing capacity of the lung.

To determine the acute effect of smoking on DLCO, we studied 12 smokers (mean age, 36 yr; range, 19 to 52 yr, six men and six women) before and after they had smoked as many cigarettes as they could (mean, 6.0; SD, 1.9) over a period of 1 h. Blood COHb was estimated using a rebreathing-breathholding technique after a vital capacity inhalation of O2. Capillary blood volume (VC) was determined from DLCO performed at inspired O2 concentrations of 25 and 90%. DLCO (in ml/min/mm Hg) corrected for COHb back pressure decreased from 22.5 (SD, 6.6) before smoking to 21.0 (SD, 6.6) after smoking (p = 0.003). After correction for the "anemia effect" of COHb, DLCO still significantly decreased, from 22.8 (SD, 6.3) before smoking to 21.8 (SD, 6.4) after smoking p = 0.01). VC (corrected for the reduction in hemoglobin by COHb) was 52.0 (SD, 20.1) ml before smoking and 46.4 (SD, 22.7) ml after smoking; this difference did not achieve statistical significance (p = 0.056). There was no significant change in DLCO or VC in six control subjects tested before and after 1 h of sham smoking of an unlit cigarette. In 12 control subjects studied before and after inhalation of 0.1% CO to result in mean COHb levels of 10.6% (SD, 1.4%), there was a slight but significant decrease in VC (mean change, 21%) and in DLCO (mean change, 4%) after correction for COHb back pressure and reduction in available hemoglobin, suggesting that CO inhalation may have a direct effect on DLCO by reducing VC.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Effect of smoking cessation on pulmonary carbon monoxide diffusing capacity and capillary blood volume.

We studied 16 smokers, with a mean age of 41 yr (SD, 12 yr) and a mean DLCO of 81% predicted (SD, 19%), before and after smoking cessation. Two subjects were able to stop smoking for only 24 h, whereas 14 subjects abstained for 1 wk, 11 for 1 month, and five for 3 months. The initial mean DLCO in ml/min/mm Hg was 18.9 (SD, 4.6) after correction for COHb back pressure and the reduction in hemoglobin because of COHb. A week after smoking cessation there was a significant increase in DLCO, to 20.8 (SD, 5.4), p = 0.001. There was no further increase in DLCO at 1 month or at 3 months. In four subjects tested while they were still smoking and 24 h after smoking cessation, there was a significant increase in DLCO after correction for COHb, from 17.4 (SD, 1.5) to 19.8 (SD, 1.3), p = 0.02. These results indicate that after smoking cessation there is a rapid improvement in DLCO, suggesting that smoking had previously decreased DLCO. However, there may also be an irreversible component to the reduction of DLCO in some of the subjects in whom the DLCO remained abnormal even after continued smoking cessation for 1 month.

Adult↗
PubMed1992

Interlaboratory and intralaboratory variability in pulmonary function testing. A 13-year study using a normal biologic control.

The purpose of this study was to document the precision with which measurements can be made on a normal subject as a "biologic control" when comparisons are made both on an intralaboratory and interlaboratory basis. One individual had a total of about 300 routine pulmonary function measurements in 22 laboratories during a 13-year period. In this study, significant variation was found in interlaboratory testing, while less variation was found in intralaboratory measurements. This technique of periodic testing of normal individuals as biologic controls is useful for documenting reproducibility and precision; evaluation of accuracy will require a check of the physical calibration of the equipment. The testing (on at least a monthly basis) of a normal nonsmoking subject as a biologic control is recommended as an integral component of quality assurance in the pulmonary function laboratory.

Humans↗
PubMed1992

Discordance of airflow limitation and ventilatory inhomogeneity in asthma and cystic fibrosis.

Although it is known that both airflow rates and gas distribution are impaired in asthma and cystic fibrosis (CF), the concordance of the change in these defects between two points in time has not been studied. On two separate occasions, the FEV1, FVC and slope of Phase III (SBN2/L%) of the single breath nitrogen test were determined, as well as the concordance between the change in these indices in 14 healthy subjects, 14 subjects with asthma, and seven subjects with CF. The coefficient of variation within a test session averaged less than 5% for the FEV1 and less than 10% for the SBN2/L% within each group. The change in FEV1 correlated with the change in FVC in all three groups, but did not correlate with the change in SBN2/L% in any group. In seven of the 14 cases of asthma and six of the seven cases of CF (outliers), the differences in the indices (expressed as the change in percent predicted) were greater than the differences observed in the control group. In three of the asthmatic and four of the CF outliers, the changes were as predicted, that is, both tests returned toward normal, or both became more abnormal. In two of the asthmatic and CF outliers both the FEV1 and SBN2/L% increased, while both decreased in the other two asthmatic outliers. Although some of the same factors will affect both indices, a worsening of ventilation inhomogeneity, which will affect the SBN2/L%, could occur with an improvement in ventilatory flow rate. Alternatively, airflow limitation could worsen but be accompanied by an improvement in ventilation homogeneity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

A sensitive double-sandwich ELISA for neutrophil elastase. Assay results in unconcentrated bronchoalveolar lavage fluid.

We developed a sensitive double-sandwich ELISA assay for neutrophil elastase (NE) using affinity-purified NE antibody. The assay was capable of detecting NE levels of 0.2 ng/ml and was used to determine NE in bronchoalveolar lavages (BAL) of 12 healthy subjects (6 nonsmokers and 6 smokers) with a mean age of about 27 yr. NE levels in the unconcentrated cell-free supernatant of BAL, subjected to high-speed centrifugation (17,000 x g for 30 min) to sediment subcellular debris, were similar in the smokers who abstained overnight from smoking and in the nonsmokers (24.4 +/- 13.9 versus 23.7 +/- 12.3 ng/mg [SD] albumin). NE levels were significantly higher in lavage fluid not subjected to high-speed centrifugation, reflecting the presence of NE bound to subcellular debris that was sedimented by high-speed centrifugation. Concentration by ultrafiltration through a Millipore CX-10 filter was accompanied by loss of protein with a relatively greater loss of NE than albumin, resulting in lower NE/albumin ratios in concentrated than in unconcentrated lavage. It is therefore recommended that NE levels be determined on unconcentrated BAL after high-speed centrifugation to sediment subcellular debris.

Adult↗
PubMed1991

Relationship between severity of rheumatoid arthritis and serum alpha 1-antitrypsin.

We determined serum alpha 1-antitrypsin phenotypes and levels in 281 patients with classical or definite rheumatoid arthritis (RA). The prevalence of the MZ phenotype in our patients with RA was not increased, as there were only 3 MZ cases (1.1% of all cases and 1.4% of seropositive cases) compared to the 3% prevalence in controls. The FM phenotype was detected in 6 cases, a prevalence rate of 2.1%, significantly higher than in controls (prevalence less than 0.4%). Increased serum levels of alpha 1-antitrypsin were independently associated (p less than 0.01) with the presence of wrist joint erosions and the use of gold and/or penicillamine for treatment; this association may represent a serum antitrypsin response to more severe disease.

Adult↗
PubMed1990

A comparison of enprofylline and theophylline in the maintenance therapy of chronic reversible obstructive airway disease.

To compare the efficacy and side effects of two xanthine derivatives in the maintenance therapy of reversible obstructive airway disease, 242 patients were assigned in randomized, double-blind fashion to receive either oral enprofylline or theophylline for 5 weeks in addition to their usual maintenance regimens. After a week of placebo xanthine therapy, enprofylline-treated patients received 150 mg of this drug twice daily (b.i.d.) for 3 days, 300 mg b.i.d. for 2 weeks, and 450 mg b.i.d. for 2 weeks. Theophylline was administered in identical doses, except that the final dosage increase was not made if plasma theophylline was 12 mg/ml or higher. At 300 mg b.i.d., both drugs significantly increased morning peak expiratory flow rate (PEFR), the mean increase above baseline being significantly higher for theophylline-treated patients (29.9 +/- 37.2 L/min) than for enprofylline-treated patients (17.4 +/- 36.9 L/min) (p = 0.023). At 450 mg b.i.d., improvement in morning PEFR was not significantly different between theophylline-treated (31.5 +/- 44.4 L/min) and enprofylline-treated groups (23.5 +/- 48.4 L/min). Evening PEFR, FEV1, and asthma symptom scores also improved significantly, demonstrating no significant difference between groups. The incidence of side effects was also similar between groups. We conclude that both enprofylline and theophylline offer useful bronchodilatation in the maintenance therapy of asthma, enprofylline, 450 mg b.i.d., being approximately equivalent to theophylline, 300 or 450 mg b.i.d.

Adolescent↗
PubMed1990

Pulmonary capillary blood volume in emphysema.

We determined single breath diffusing capacity (DLCO) and pulmonary capillary blood volume (Vc) in a total of 110 patients, who were being evaluated for resectional lung surgery for a localized tumor or lesion. Pathologic assessment of emphysema was obtained in 55 cases who had resection of a lung or an upper lobe, based on a standard reference panel for emphysema grading. In 86 cases, the extent of emphysema was quantitated by computed tomography (CT) of the chest. There was a significant negative correlation between Vc and emphysema assessed by either pathology or CT (r = about -0.5, p less than 0.001) similar to the correlation between DLCO and the extent of emphysema. Results of Vc were significantly lower in cases with moderate emphysema (pathologic grade greater than or equal to 30) than those with no emphysema (grade less than or equal to 5) (p less than 0.001) or mild emphysema (grade 10 to 25) (p less than 0.05), and they were significantly lower (p less than 0.05) in the group with mild emphysema compared with the group with no emphysema on pathologic assessment similar to DLCO results. Although Vc was reduced in emphysema, determination of Vc did not result in improved discrimination in separating cases with emphysema from those without emphysema when compared with DLCO.

Adult↗
PubMed1990

Emphysema in silicosis. A comparison of smokers with nonsmokers using pulmonary function testing and computed tomography.

The presence of emphysema in silicosis is believed to be secondary to the development of progressive massive fibrosis (PMF). However, it is difficult to separate out other causative factors, particularly cigarette smoking. In order to attempt to distinguish these factors, we examined 30 patients with silicosis by means of pulmonary function testing and computed tomography (CT) scans of the chest. Eighteen of these patients were either exsmokers or current smokers, and 12 of them were nonsmokers. The CT scans were read independently by two observers on two separate occasions. Silicosis was graded on a 5-point scale from 0 to 4; emphysema was graded as a percentage of lung involved. Percent emphysema was associated with level of pulmonary function (FEV1, FVC, and DLCO) independent of its association with either cigarette smoking or silicosis grade (p less than 0.01). Silicosis grade was associated with DLCO (p less than 0.05) independent of its association with either cigarette smoking or percent emphysema, but was not associated with level of FEV1 or FVC. In the group without PMF (silicosis Grade 0, 1, or 2), smokers had worse emphysema than nonsmokers (p less than 0.01); there was no such difference among the patients with PMF (silicosis Grade 3 or 4). Only one of the nonsmoking subjects with silicosis but without PMF had any emphysema detected on CT. Our data suggest that silicosis, in the absence of PMF, does not cause significant emphysema, and that it is primarily the degree of emphysema rather than the degree of silicosis that determines the level of pulmonary function.

Adult↗
PubMed1990

Quantitation of emphysema by computed tomography using a "density mask" program and correlation with pulmonary function tests.

We used a CT program "density mask" outlining areas with attenuation values less than -910 HU, to indicate areas of emphysema on a chest CT and to provide an overall percentage of lung involvement by emphysema. The "density mask" quantitation of emphysema was previously shown to correlate well with the pathologic assessment of emphysema in patients undergoing lung resection. We compared the CT quantitation of emphysema with mean lung density, overall lung volume on CT and pulmonary function tests in 85 patients. There was a significant correlation between the extent of emphysema on CT and FEV/FVC percent of predicted, functional residual capacity percent predicted and Dsb percent predicted. Determination of the percentage of lung with areas of low attenuation by CT provides a useful method for quantitating emphysema in life and correlates significantly with pulmonary function tests.

Adult↗
PubMed1989

Comparison of single breath carbon monoxide diffusing capacity and pressure-volume curves in detecting emphysema.

To evaluate the sensitivity of diffusing capacity (DLCO) and pressure-volume (P-V) curves in the detection of emphysema, these tests were compared with pathologic assessment of emphysema in patients undergoing lung resection for a localized tumor, and with the overall extent of emphysema as assessed by computed tomography (CT). The resected lung specimens were fixed in the inflated state and cut at 1-cm intervals in the horizontal plane. The pathologic extent of emphysema was quantitated by comparison with a standard reference panel of emphysema grading. The overall extent of emphysema on CT was assessed by a visual scoring system in a total of 55 patients, 19 undergoing lung resection and 36 not undergoing lung resection. Analysis of 37 patients by pathology scores revealed 18 with no or trivial emphysema (emphysema grades less than or equal to 5; mean grade, 2.2 +/- SD 2.6) and 19 with emphysema (grades greater than or equal to 10; mean grade, 33.2 +/- SD 24.2). Diffusing capacity, the ratio of DLCO to alveolar volume (DLCO/VA), maximal lung elastic recoil (PLmax), and lung elastic recoil at 90% of total lung capacity (PL90) were significantly different between the two groups, whereas K (the exponential constant describing the shape of the P-V curve) was not. The pathology grade of emphysema showed a significant correlation with (DLCO) (r = -0.53) and DLCO/VA (r = -0.55), which was greater than the correlation with PLmax (r = -0.42) and PL90 (r = -0.43).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Goodpasture's syndrome: recurrence after a five-year remission. Case report and review of the literature.

Herein is reported the case of a man who has had a recurrence of Goodpasture's syndrome following a five-year remission. The patient presented initially in 1977 at the age of 28 with Goodpasture's syndrome manifested by pulmonary hemorrhage without clinical evidence of renal disease, and positive antiglomerular basement membrane antibody. Following treatment with corticosteroids, remission occurred and the serum antiglomerular basement membrane antibody became negative. In 1983, he experienced a relapse with the reappearance of serum antiglomerular basement membrane antibody, the development of severe life-threatening intrapulmonary hemorrhage, and hematuria. This case illustrates that life-threatening relapse may occur in Goodpasture's syndrome despite a prolonged remission and the disappearance of detectable antiglomerular basement membrane antibody in the circulation.

Adrenal Cortex Hormones↗
PubMed1988

Bronchial leukocyte proteinase inhibitor levels in bronchial washings in asthma patients.

To evaluate whether epithelial damage of airways in asthma could be related to diminished levels of the low molecular weight bronchial leukocyte proteinase inhibitor (BLPI) in airways, we determined BLPI in bronchial washings of 13 asthma patients and 13 healthy subjects, using a sensitive enzyme-linked immunoassay. The patients had asthma due to western red cedar and had bronchial washings done 24 to 48 hours after a mild to moderate asthmatic reaction induced by inhalation challenge. We did not find significant differences in BLPI concentrations in lavage fluid of asthma patients and healthy control subjects. The ratios of BLPI to albumin levels in bronchial washings appeared to be lower among asthmatic patients, but this difference was mainly due to an increase in albumin levels in lavage fluid in asthma. In addition, there were no significant differences in BLPI levels in washings obtained from main and segmental bronchi in both control subjects and asthma patients.

Adult↗
PubMed1988

"Density mask". An objective method to quantitate emphysema using computed tomography.

We used a computed tomography (CT) scanner program ("density mask") that highlights voxels within a given density range to quantitate emphysema by defining areas of abnormally low attenuation. We compared different density masks, mean lung attenuation, visual assessment of emphysema and the pathologic grade of emphysema in 28 patients undergoing lung resection for tumor. In each patient, a single representative CT image was compared with corresponding pathologic specimens of tissue. There was good correlation between the extent of emphysema as assessed by the density mask and the pathologic grade of emphysema. The optimal attenuation level to define areas of emphysema may vary in different scanners, but, once determined for a particular scanner, the density mask accurately assesses the extent of emphysema and eliminates interobserver and intraobserver variability. It has the added advantage of determining the exact percentage of lung parenchyma showing changes consistent with emphysema.

Adult↗
PubMed1987

Noncardiogenic pulmonary edema caused by decompression sickness: rapid resolution following hyperbaric therapy.

Noncardiogenic pulmonary edema is a recognized but uncommon manifestation of type 2 decompression sickness. It typically occurs within 6 hours of a dive. Because the adult respiratory distress syndrome in this setting is believed to be due to microbubbles in the pulmonary vasculature, recompression in a hyperbaric chamber has been recommended as a form of therapy. A patient developed noncardiogenic pulmonary edema following a seawater dive to 75 feet. There was complete radiologic and clinical resolution within 5 hours of hyperbaric therapy.

Adult↗
PubMed1987

Effect of smoking on functional activity of plasma alpha 1-protease inhibitor.

We determined the levels of alpha 1-protease inhibitor, the plasma trypsin-inhibiting capacity (TIC), and elastase-inhibiting capacity (EIC) in 29 nonsmokers and 30 smokers, who were healthy volunteers matched for age (mean age, 39 +/- 12 years [+/- SD]). The functional activity of plasma alpha 1-protease inhibitor (in micrograms of enzyme inhibited per microgram of alpha 1-protease inhibitor) was slightly but significantly lower in smokers, compared with nonsmokers, both for TIC and EIC (smokers' TIC and EIC were 88.0 +/- 16.2 percent (+/- SD) and 90.4 +/- 17.9 percent of the respective mean values in nonsmokers; p less than 0.05). Among smokers, there was a significant negative correlation (r = -0.37; p less than 0.05) between the average number of cigarettes smoked per day and the functional activity of plasma alpha 1-protease inhibitor; the seven subjects who smoked 40 or more cigarettes per day had significantly lower EIC and TIC than the remaining smokers. In 12 smokers tested before and after a two-hour period of intense smoking of eight cigarettes, there was a statistically significant decrease (p less than 0.05) in EIC one hour after smoking to 93.9 +/- 2.5 percent (+/- SE) of the initial value prior to smoking. It is concluded that there is a slight but significant decrease in the functional activity of plasma alpha 1-protease inhibitor in smokers, both for TIC and EIC.

Adult↗