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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
PubMed2006

Stability of housekeeping genes in alveolar macrophages from COPD patients.

The stability of housekeeping genes is critical when performing gene expression studies. To date, there have been no studies that look at the stability of commonly used housekeeping genes in alveolar macrophages. Expression levels may be affected by culture, stimulation or disease severity. The present study investigated the expression level of 10 housekeeping genes and analysed the stability of their expression in alveolar macrophages from chronic obstructive pulmonary disease patients (n = 22) who were classified according to disease severity. Guanine nucleotide-binding protein, beta polypeptide 2-like 1 (GNB2L1), hypoxanthine phosphoribosyl transferase 1 (HPRT1) and ribosomal protein L32 (RPL32) were the most stably expressed in alveolar macrophages, irrespective of disease severity. There was no difference in the expression levels of 10 housekeeping genes between mild and moderate/severe patients. GNB2L1, HPRT1 and RPL32 were also stably expressed in alveolar macrophages cultured with no stimulation, or with interleukin-1beta, lipopolysaccharide or tumour necrosis factor-alpha stimulation. In conclusion, as fluctuations in the expression of some housekeeping genes were observed, including glyceraldehyde-3-phosphate dehydrogenase, it is recommended that guanine nucleotide binding protein, beta polypeptide 2-like 1 be used as a reference gene for alveolar macrophages in similar study designs, or that the stability of housekeeping genes be validated in alveolar macrophages prior to expression studies.

Aged↗
PubMed2001

Impaired exercise performance after successful liver transplantation.

BACKGROUND: Recipients of heart, lung, and kidney transplants have impaired peak exercise performance (peak Vo2 40% to 60% predicted, reduced anaerobic threshold [AT]) without evidence of ventilatory or cardiac limitations. The aim of this study was to determine whether similar exercise impairment occurs in liver transplant recipients. METHODS: We studied eight healthy liver transplant recipients (age 42+/-9 [SD] years, 6 male, 31+/-13 months posttransplant). Immunosuppression included FK506 or cyclosporine, azathioprine or mycophenolate mofetil, and prednisone. Subjects underwent lung function testing and cardiopulmonary exercise testing on a cycle ergometer. RESULTS: Peak exercise oxygen consumption (Vo2) was 22+/-8 ml/min/kg (66+/-20% predicted maximum). No subject demonstrated exercise desaturation or ventilatory limitation (peak minute ventilation 55+/-8% predicted maximum voluntary ventilation). Peak heart rate was 87+/-8% of predicted maximum. Early AT was evident (1.2+/-0.34 L/min, 48+/-11% predicted Vo2max). CONCLUSIONS: Liver transplant recipients exhibit impaired peak exercise performance similar to that observed after other solid organ transplants, possibly as a result of chronic deconditioning or myopathy related to immunosuppressive medications.

Adult↗
PubMed2000

Role of CO diffusing capacity during exercise in the preoperative evaluation for lung resection.

We conducted a prospective study to evaluate whether lack of an adequate increase in diffusing capacity for carbon monoxide (DL(CO)) during exercise is associated with a greater postoperative complication rate after lung resection. We used the three-equation method (3EQ-DL(CO)), a modification of the single breath DL(CO) technique to determine DL(CO) during exercise in 57 patients undergoing lung resection at Vancouver General Hospital from October 1998 to May 1999. 3EQ-DL(CO) was determined during steady-state exercise at 35% and 70% of the maximal workload reached in a progressive exercise test. Maximal oxygen uptake (VO(2)max), DL(CO) at rest, and the increase in DL(CO) during exercise were compared in relation to postoperative complications. Patients with complications had lower resting values of DL(CO) (R-DL(CO)), a smaller increase in DL(CO) from rest to 70% of maximal workload expressed as a percent of the predicted DL(CO) at rest ([70% - R]-DL(CO)%), and a lower VO(2)max than did patients without complications. Results suggested that (70% - R)-DL(CO)% was the best preoperative predictor of postoperative complications; a cutoff limit of 10% was the best index to identify complications, yielding a complication rate of 100% in patients with (70% - R)-DL(CO)% < 10% as compared with a complication rate of 10% in patients with (70% - R)-DL(CO)% >/= 10% (sensitivity = 78%, specificity = 100%). Patients who do not increase their DL(CO) sufficiently during exercise ([70% - R]-DL(CO)% < 10%) have a greater complication rate after lung resection.

Aged↗
PubMed1999

Effects of side lying on lung function in older individuals.

BACKGROUND AND PURPOSE: Body positioning exerts a strong effect on pulmonary function, but its effect on other components of the oxygen transport pathway are less well understood, especially the effects of side-lying positions. This study investigated the interrelationships between side-lying positions and indexes of lung function such as spirometry, alveolar diffusing capacity, and inhomogeneity of ventilation in older individuals. SUBJECTS AND METHODS: Nineteen nonsmoking subjects (mean age=62.8 years, SD=6.8, range=50-74) with no history of cardiac or pulmonary disease were tested over 2 sessions. The test positions were sitting and left side lying in one session and sitting and right side lying in the other session. In each of the positions, forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), single-breath pulmonary diffusing capacity (DLCO/VA), and the slope of phase III (DN2%/L) of the single-breath nitrogen washout test to determine inhomogeneity of ventilation were measured. RESULTS: Compared with measurements obtained in the sitting position, FVC and FEV1 were decreased equally in the side-lying positions, but no change was observed in DLCO/VA or DN2%/L. CONCLUSION AND DISCUSSION: Side-lying positions resulted in decreases in FVC and FEV1, which is consistent with the well-documented effects of the supine position. These findings further support the need for prescriptive rather than routine body positioning of patients with risks of cardiopulmonary compromise and the need to use upright positions in which lung volumes and capacities are maximized.

Aged↗
PubMed1998

Airway wall thickness in patients with near fatal asthma and control groups: assessment with high resolution computed tomographic scanning.

BACKGROUND: Airway wall thickening has been observed in post mortem studies of patients with asthma. Assessment of airway wall thickening by high resolution computed tomographic (HRCT) scanning has been reported in experimental studies. We have used HRCT scanning to measure airway wall thickness at the segmental and subsegmental levels in 40 patients with asthma and 14 normal controls. METHODS: The subjects were prospectively divided into four age and sex matched groups: 14 patients with a history of near fatal attack of asthma (NFA; group 1), 12 patients with moderate asthma (group 2), 13 patients with mild asthma (group 3), and 14 normal controls (group 4). All subjects were non-smokers. High resolution (1 mm collimation) CT scans of the chest were done at five different levels. RESULTS: The mean (SD) forced expiratory volume in one second (FEV1) was 68 (20)% of predicted for group 1, 73 (12)% for group 2, 102 (12)% for group 3, and 103 (12)% for group 4. The ratio of airway wall thickness to outer diameter (T/D) and the percentage wall area (WA%) defined as (wall area/total airway area) x 100 were used to compare airway wall thickness between the groups. The mean (SD) T/D and WA% were 0.27 (0.05) and 78.0 (9.2)% for group 1, 0.27 (0.05) and 78.8 (9.2)% for group 2, 0.25 (0.04) and 74.2 (7.5)% for group 3, and 0.23 (0.04) and 70.9 (8.2)% for group 4. T/D and WA% were not significantly different between groups 1 and 2. However, both groups 1 and 2 had higher T/D and WA% than either group 3 or 4 (p < 0.001) and group 3 had a higher T/D and WA% than group 4 (p < 0.03). The differences (95% CI) between the groups in WA% were 7.1% (0 to 14.4) for groups 1 and 4, 3.8% (-3.4 to 10) for groups 1 and 3, and 3.3% (-4.4 to 10) for groups 3 and 4. The differences between the groups in T/D and WA% were noted both for those with airways with a luminal diameter of > 2 mm and those with a luminal diameter of < or = 2 mm. CONCLUSIONS: All the patient groups had greater airway wall thickening than the normal subjects as assessed by HRCT scanning, but patients with more severe asthma had greater airway wall thickening than those with mild asthma. The methodology described in this study may be useful in assessing airway calibre in early intervention studies with anti-inflammatory therapy.

Adult↗
PubMed1998

Time course of neutrophil and macrophage elastinolytic activities in cigarette smoke-induced emphysema.

The aim of this study was to compare the time course of neutrophil and macrophage elastinolytic potentials in the lungs of rats exposed daily to cigarette smoke inhalation for 1-6 mo in relation to the onset and progression of cigarette smoke-induced emphysema. Normal room air-exposed rats served as controls. Morphometric data of lung histological sections showed evidence of emphysema lesions in the lungs of smoke-exposed rats at month 2 and continuing to month 6. Data of total and differential cell counts in bronchoalveolar lavage fluid and collagenase-dissociated lung showed an increased number of lung neutrophils at month 1 of smoke exposure, but this was reduced to control levels at months 2-6. In contrast, an increased number of lung macrophages was evident in the smoke-exposed rats at month 2 of exposure and continued to month 6. Data of the elastinolytic activities of the neutrophils and macrophages, determined in [3H]elastin-coated culture wells, showed that the elastinolytic activity of lung neutrophils in the smoke-exposed rats was similar to that of the control air-exposed rats at months 1-6 of exposure. In contrast, the elastinolytic activity of lung macrophages in the smoke-exposed rats was increased at month 2 of exposure and remained increased at month 6. Excessive in vivo lung elastin breakdown (judged by increased levels of elastin-derived peptides and desmosine in lavage fluid, determined immunologically) was observed in the smoke-exposed rats at months 2-6 of exposure. These data indicate that the time course of increased macrophage-directed elastinolytic activity in the lung, not that of neutrophils, is more closely associated with the evolution of cigarette smoke-induced emphysema.

Animals↗
PubMed1998

Relationship of alveolar macrophage plasminogen activator and elastase activities to lung function and CT evidence of emphysema.

OBJECTIVE: To evaluate the relationship between alveolar macrophage (AM) elastase and plasminogen activator (PA) activities (considered to be potential pathogenetic factors in emphysema) and the development of emphysema in smokers. PARTICIPANTS: Thirty-four healthy smokers >35 years of age (mean+/-SD, 46+/-7 years), with a mean+/-SD of 33+/-10 pack-years of smoking, who were recruited as volunteers. METHODS: Subjects had lung function testing and BAL to obtain AMs; limited high-resolution CT scans of the chest were obtained in 32 subjects to assess the presence of emphysema. Macrophage PA and elastase were determined using AM cultured on (131)I-fibrin-coated plates and 3H-elastin-coated plates, respectively. RESULTS: The number of AMs recovered per milliliter of BAL was significantly greater in the 16 subjects with CT evidence of mild emphysema than the 16 subjects without evidence of emphysema (669+/-301 x 10(3)/mL vs 414+/-268x 10(3)/mL; p=0.01). There was no significant difference between AM elastase or PA activities in the 16 subjects with CT evidence of mild emphysema, when compared with the 16 subjects who had no CT evidence of emphysema (elastase, 2.72+/-1.35 microg vs 2.49+/-0.91 microg elastin per 10(6) AMs per first 24 h; PA, 0.375+/-0.126 vs 0.344+/-0.096 urokinase units/10(6) AMs). There was no significant correlation between levels of PA or elastase activities and FEV1, FEV1/FVC, forced expiratory flow rate between 25% and 75% of the FVC; PA activity but not elastase activity had a significant negative correlation (r=-0.47, p<0.01) with diffusion of carbon monoxide (DCO). The macrophage count in BAL had a significant negative correlation with DCO percent predicted (r=-0.61, p<0.001). CONCLUSIONS: The findings suggest that the number of AMs recovered per milliliter of BAL (presumably indicating the number in the alveolar spaces) is related to the development of emphysema in smokers as indicated by CT scan of the chest and DCO. The results also suggest that the level of PA enzyme activity in AMs may be a pathogenetic factor in the decrease in DCO in smokers.

Adult↗
PubMed1997

Albuterol via Turbuhaler versus albuterol via pressurized metered-dose inhaler in asthma.

BACKGROUND: Inhaled albuterol is most commonly self-administered by patients using a pressurized metered-dose inhaler (pMDI) but patients often have difficulty using the device. Dry powder devices such as the multi-dose, inspiratory flow driven inhaler (Turbuhaler) are often better handled by patients. OBJECTIVE: We sought to compare the efficacy and tolerability of 100 micrograms of albuterol delivered by a multi-dose, inspiratory flow driven inhaler (Turbuhaler) to a standard dose (200 micrograms) delivered by a pMDI (Ventolin) in chronic reversible obstructive airways disease. METHOD: In 6 centers, we studied 37 adults [19 men and 18 women, mean age 39 +/- 12 years; mean baseline forced expiratory volume in one second (FEV1) 72 +/- 13% (% predicted)] with stable but symptomatic reversible obstructive airways disease as demonstrated by 15% or greater increase in FEV1 following two puffs (200 micrograms) albuterol by pMDI. The crossover design comprised a 1-week run-in and two 2-week treatment periods separated by a 1-week washout. At the start and end of each treatment period, FEV1 was measured at the clinic. Patients self-administered albuterol 100 micrograms (2 x 50 micrograms) via Turbuhaler or 200 micrograms (2 x 100 micrograms) via pMDI in a double-blind fashion four times daily. Morning and evening peak expiratory flow (PEF) was noted daily. All non-study bronchodilators were withheld while open-label albuterol pMDI was offered for rescue. RESULTS: Of the 37 patients, 30 used inhaled steroids in constant doses throughout the study, one used inhaled cromoglycate and six used no anti-inflammatory therapy. There was no difference between treatment periods in morning PEF, diurnal fluctuation in PEF, increase in PEF following study drug, baseline FEV1 and FEV1 increase following study drug. Although there was no difference in symptom scores between treatments, the use of rescue beta 2-agonist was slightly but significantly higher during the Turbuhaler treatment period (1.34 versus 1.08 inhalations/ day, P = .04). Compliance with study drug was slightly but significantly lower during the Turbuhaler treatment period (87 versus 95%) such that the total number of beta 2-agonist puffs inhaled (scheduled plus rescue) was similar between treatments. With regard to adverse events, both treatments were well tolerated. CONCLUSIONS: These results suggest that the efficacy and tolerability of albuterol 100 micrograms qid inhaled via Turbuhaler is similar to albuterol 200 micrograms qid, inhaled via pMDI in stable reversible obstructive airways disease.

Adult↗
PubMed1997

Effect of exposure of guinea pigs to cigarette smoke on elastolytic activity of pulmonary macrophages.

STUDY OBJECTIVE: To determine the effect of exposure to cigarette smoke on the elastolytic activity of guinea pigs' alveolar macrophages (AMs), and to compare elastolytic activity of AMs obtained by BAL with that of lung macrophages (LMs) obtained from minced lung tissue. METHODS: AMs were obtained by BAL from seven adult guinea pigs exposed to cigarette smoke for 5 d/wk during 6 weeks, as well as from age-matched control guinea pigs. From each animal, one lung was used to obtain LMs by mincing and teasing the lung, followed by enzymatic digestion and isolation of mononuclear cells by Hypaque-Ficoll separation. The other lung was inflated and fixed to quantitate emphysema by the destructive index (DI). Elastolytic activity (microgram of elastin degraded by 10(6) macrophages) was determined at 24, 48, and 72 h, by culturing AMs and LMs (1 x 10(6) cells in 1 mL of medium) in 3H-elastin-coated wells. RESULTS: In animals exposed to cigarette smoke, the total number of BAL cells (8.6+/-2.1 x 10(6)) and DI (21.8+/-8.1) were significantly higher than in nonexposed animals (6.4+/-1.8 x 10(6), p<0.05 for cells, and 12.1+/-4.1, p<0.01 for DI). Elastolytic activity of AMs from smoke-exposed guinea pigs was significantly higher at 24, 48, and 72 h than elastolytic activity of AMs from control animals (19.0+/-9.4 vs 10.0+/-5.3, p<0.05 at 72 h). Likewise, elastolytic activity of LMs was significantly higher in exposed than nonexposed guinea pigs (11.8+/-7.7 vs 7.4+/-5.0 at 72 h, p<0.05). Elastolytic activity of LMs was not significantly different from elastolytic activity of AMs, both in exposed guinea pigs (11.8+/-7.7 vs 19.0+/-9.4 at 72 h) and nonexposed animals (7.4+/-5.0 vs 10.0+/-5.3 at 72 h). CONCLUSIONS: These results indicate that elastolytic activity of both AMs and LMs of guinea pigs increases significantly after exposure to cigarette smoke and that AMs and LMs have similar elastolytic activities.

Animals↗
PubMed1996

Cardiovascular safety of high doses of inhaled fenoterol and albuterol in acute severe asthma.

BACKGROUND: It has been suggested that overuse of fenoterol metered-dose inhalers (MDIs) may increase the risk of death from asthma due to cardiac arrhythmias. Our primary objective was to compare the cardiovascular safety of fenoterol and albuterol MDIs when administered in maximal bronchodilating or maximal tolerated doses to an absolute maximum of 16 puffs, for the emergency department (ED) treatment of acute severe asthma. METHODS: Asthmatic patients presenting to the ED with acute severe asthma (FEV1 less than 50% of predicted) were enrolled in a multicenter, randomized, double-blind, parallel-group study. Following baseline measurements, (medical history, physical examination, determination of serum potassium and serum theophylline levels, oximetry, 12-lead ECG, and spirometry), each patient received 4 puffs of either fenoterol, 200 micrograms per puff, or albuterol, 100 micrograms per puff, 1 puff every 30 s via an MDI attached to a holding chamber. Additional doses of inhaled beta 2-agonist were administered by dose titration, 2 puffs every 10 min to a maximal cumulative dose of 16 puffs of albuterol or fenoterol, side effects were intolerable to the patient, or an FEV1 plateau (i.e., < 10% improvement for 2 consecutive doses) occurred. ECG was recorded continuously via Holter monitor, and respiratory rate, BP, dyspnea (Borg scale), and FEV1 were assessed after each dose. RESULTS: 128 patients were randomized to receive fenoterol and 129 to receive albuterol. Overall, fenoterol increased FEV1 160 mL more than albuterol. The mean (SEM) FEV1 increase from baseline was 0.75 +/- 0.06 L in the fenoterol group and 0.59 +/- 0.06 L in the albuterol group (p < 0.03). Both beta 2-agonists caused a decrease in serum potassium level that was significantly greater in the fenoterol (0.23 +/- 0.04 mmol/L) than in the salbutamol (0.06 +/- 0.03 mmol/L) group (p = 0.0002). There was also a greater increase in the Q-Tc interval in the fenoterol group, 0.011 +/- 0.003 s compared with 0.003 +/- 0.003 s in the albuterol group (p < 0.05). Differences in hypokalemia and Q-Tc prolongation associated with fenoterol and albuterol were significantly different only after 8 puffs of fenoterol had been given. 32 patients exhibited ventricular premature beats, 14 in the fenoterol group and 18 in the albuterol group. There were 34 patients with episodes of supraventricular premature beats, 17 in each group. No episodes of sustained ventricular tachycardia were detected in either group. CONCLUSIONS: In adequately oxygenated patients, using dose titration of fenoterol, in a formulation of 200 micrograms per puff by MDI valved holding chamber and mask, to a total dose of 3,200 micrograms and salbutamol (100 micrograms per puff) to a total dose of 1,600 micrograms over 90 min, showed cardiovascular safety in acute severe asthma. This was evidenced by absence of cardiovascular mortality or clinically significant arrhythmias in either group. The 100% greater dose of fenoterol improved FEV1 significantly more than salbutamol and was associated with a relatively small but significantly greater prolongation of the Q-Tc interval and decrease in serum potassium level. This study does not exclude the possibility that adverse cardiac events could occur with severe hypoxemia.

Acute Disease↗
PubMed1995

Assessment of the antielastase activities in bronchoalveolar lavage fluid: effect of assay buffer ionic strength.

OBJECTIVE: To evaluate the effect of assay buffer ionic strength on assessment of the antielastase activities in bronchoalveolar lavage fluid. METHOD: An improved assay protocol in which elastase (in Tris-HCI buffer) is added to increasing volumes of test samples (made up to equal volume with phosphate-buffered saline) was used. RESULTS: The percent NE activity inhibited by BALF decreased with increasing NaCl concentration of the buffer. Inhibition of pancreatic elastase (PE) was not affected. One hundred percent inhibition of NE by pure AAT and SLPI standards occurred at molar ratios of 0.91 +/- 0.03 for AAT-to-NE and 0.83 +/- 0.02 for SLPI-to-NE when assayed in buffer with < or = 0.15 mol NaCl/L, compared to ratios of 0.99 +/- 0.02 and 1.06 +/- 0.02, respectively, for assays in buffers with 0.50-1.00 mol NaCl/L (p < 0.05 for AAT-to-NE; p < 0.02 for SLPI-to-NE). The AAT-to-PE molar ratio at 100% inhibition of PE was not affected. Assays in buffer with < or = 0.15 mol NaCl/L indicated that 86.9 +/- 4.1% of AAT and 100.9 +/- 4.9% of SLPI in BALF were active against NE, while assays in buffer with 0.50-1.00 mol NaCl/L showed that 84.4 +/- 3.5% of AAT and 81.6 +/- 5.9% of SLPI present were active. AAT inhibited NE and PE equally only in buffer with 0.50-1.00 mol NaCl/L. CONCLUSIONS: The results of assays of BALF antielastase activities depend on the assay buffer NaCl concentration, which may account for the conflicting reports in the literature. The buffer with 0.50-1.00 mol NaCl/L appear to be optimal for valid quantitation of anti-NE activities in BALF.

Adsorption↗
PubMed1995

The effect of menstruation on the pulmonary carbon monoxide diffusing capacity.

We studied variations in DLCO during the menstrual cycle in 14 healthy women with a mean age of 29 (SD, 7) yr. Eight were using oral contraceptives, and six were not. DLCO was determined 1 to 7 d before the onset of menses, daily during each of the first 4 d of menses, and 5 to 10 d after onset of menses. In both groups of subjects, the highest values for DLCO were obtained before menses, the lowest were on the third day of menses, whereas after completion of menses the values increased but were not as high as prior to menses. The mean DLCO for all subjects was 23.1 (SD, 3.2) ml/min/mm Hg before menses, 20.9 (SD, 3.0) on the third day of menstruation, and 21.6 (SD, 3.3) 5 to 10 d after onset of menses. The mean percent difference between DLCO before and on the third day of menses in all 14 subjects was 9.2 (SD, 4.4) %. There were no significant changes in hemoglobin on these days to account for the changes in DLCO. Pulmonary capillary blood volume determined in 10 of the subjects did not show a significant change. It is concluded that DLCO can vary significantly during the menstrual cycle, with the highest values occurring prior to menses and the lowest values occurring on the third day of menses, with a mean difference between them of 9%. These variations need to be considered when evaluating DLCO in female patients in the menstrual age group.

Adult↗
PubMed1994

Effect of assay conditions on measurement of elastolytic activity of alveolar macrophages in culture and characterization with proteinase inhibitors.

We have investigated whether varied assay conditions account for the conflicting reports on measured elastolytic activity of alveolar macrophages (AM) cultured in direct contact with the 3H-elastin substrate coated onto 16-mm wells in serum-containing media. The data indicate that measured elastolytic activity in this assay system was dependent on the amount of 3H-elastin/culture well. 3H-elastin > 350 micrograms/well, in contrast to the < or = 200 micrograms/well commonly used in this assay system, resulted in optimal measurement of elastolytic activity that was linear with respect to culture time (up to 72 h examined) and was directly proportional to number of AM/well (up to 1.0 x 10(6) examined). The sensitivity of measured elastolytic activity to tissue inhibitor of metalloproteinases (TIMP) and to Z-phe-phe (a specific cysteine proteinase inhibitor) was not affected by amount of 3H-elastin/well, but appears to be dependent on the time period of AM culture. TIMP (at 5 microM, maximal dose examined) inhibited the measured elastolytic activity by 25% in 24-h cultures compared to 69% in 72-h cultures; Z-phe-phe (at 10 microM, dose at which maximal effect was obtained) inhibited the elastolytic activity by 45% in the 24-h cultures compared to 34% in the 72-h cultures. These findings indicate that differences in substrate levels and in culture time have a significant effect on the results obtained in measurement of AM-mediated elastolytic activity in culture, which may account for the conflicting reports in the literature. Thus standard optimal assay condition are required for valid interpretation of results of AM-mediated elastolytic activity measurements.

Biological Assay↗
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↗