Size matching in lung transplantation using predicted total lung capacity.

Height is used in allocation of donor lungs as an indirect estimate of thoracic size. Total lung capacity (TLC), determined by both height and sex, could be a more accurate functional estimation of thoracic size. Size-matching criteria based on height versus predicted TLC was retrospectively evaluated, and, furthermore, whether a TLC mismatch was related to clinical and functional complications. The ratio of donor and recipient height, as well as the ratio of predicted TLC in donors and recipients, were calculated in 80 patients after bilateral lung transplantation. Complications evaluated included persistent atelectasis, persistent pneumothorax and increased number of days in intensive care, occurrence of bronchiolitis obliterans syndrome and limitation of exercise capacity. Median height donor/recipient ratio was 1.01 (0.93-1.12). Median predicted TLC donor/recipient ratio was 1.01 (with a clearly broader range 0.72-1.41). Neither sex mismatch nor TLC mismatch were related to clinical or functional complications. Allocation of donor lungs based upon height alone leads to a substantial mismatch in total lung capacity caused by sex mismatch. The absence of complications suggests that a greater height donor/recipient discrepancy can be accepted for allocation than previously assumed.

Pulmonary diffusion abnormalities in relation to cytomegalovirus antigenemia and cytomegalic endothelial cells in blood.

The pathophysiology of HCMV infection may involve many different organs including the lungs. In this study we investigated HCMV antigenemia levels and cytomegalic endothelial cells (CEC) in blood in relation to the pulmonary diffusion capacity. Patients with high HCMV antigenemia (> or = 100 pp65+ PMNs/50.000) (n = 8) showed a more extensive decrease in the membrane factor (Dm) than patients with lower levels of HCMV antigenemia (n = 7). The decline of the diffusion capacity of the alveolar capillary membrane (KCOc) and of the pulmonary capillary volume (Vcap) was the same in both groups. Four out of nine patients had CEC in the range of 0.22 CEC/ml to 30.26 CEC/ml. All the HCMV patients showed a decreased KCOc together with a decrease of Dm and Vcap but no difference was observed between patients with and without CEC. We conclude that a higher viral load is associated with a more extensive decrease in the membrane factor and therefore with more subclinical pneumonitis. No relation was observed between CEC and pulmonary dysfunction. Therefore, we postulate that CEC levels are related indirectly to subclinical pneumonitis mediated via the viral load.

Diffusion capacity and haemodynamics in primary and chronic thromboembolic pulmonary hypertension.

The transfer factor of the lung for carbon monoxide (TL,CO) is decreased in patients with pulmonary hypertension. The pulmonary membrane diffusion capacity (Dm) and pulmonary capillary blood volume (Vc), were studied to establish: 1) the relative contribution of the components of the transfer factor to the decrease in TL,CO; 2) whether differences exist between primary pulmonary hypertension (PPH) and chronic thromboembolic pulmonary hypertension (CTEPH); and 3) the relationship between these parameters and haemodynamic parameters. Dm and Vc were determined in 19 patients with PPH and in eight patients with CTEPH. The patients had been referred for consideration for lung transplantation. Haemodynamic parameters were assessed by heart catheterization. In the PPH group, Vc was reduced in 12 of 19 patients (mean+/-SD Vc 72+/-14% of the predicted value) and Dm in 17 of 19 patients (60+/-22% pred). In the CTEPH group, Vc was reduced in six of eight patients and Dm in seven of eight patients. The mean TL,CO Dm and Vc values were similar to those in the PPH group. The reduction in pulmonary membrane diffusion capacity was significantly greater than that in pulmonary capillary blood volume. No differences in pulmonary and cardiovascular functional values were found between the groups. Right atrial pressure showed a significant negative correlation with pulmonary capillary blood volume and an increased pulmonary vascular resistance was associated with a decrease in pulmonary membrane diffusion capacity. These results suggest pronounced functional impairment of the alveolocapillary membrane in these patients.

Airway inflammation and hyperresponsiveness to adenosine 5'-monophosphate in chronic obstructive pulmonary disease.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is often accompanied by bronchial hyperresponsiveness (BHR). Measurement of BHR may give information about airway inflammation. OBJECTIVE: To investigate the role of airway inflammation in hyperresponsiveness to adenosine 5'-monophosphate (AMP) in COPD. METHODS: We investigated inflammatory indices in induced sputum, bronchoalveolar lavage (BAL) fluid and bronchial biopsies in subjects with COPD with and without hyperresponsiveness to AMP. Twelve nonatopic subjects with COPD with hyperresponsiveness to AMP (mean +/- SD, age 63 +/- 8 years, FEV1% predicted 56 +/- 13%), six without BHR (age 60 +/- 6 years, FEV1% predicted 65 +/- 11%) and 11 healthy nonatopic controls without BHR (age 58 +/- 8 years, FEV1% predicted 104 +/- 11%) participated in the study. RESULTS: Subjects with COPD with BHR had significantly higher numbers of mucosal CD8 + and higher percentages of sputum eosinophils than those without BHR (median, 550 cells/mm2; range, 30-1340 vs 280 cells/mm2; range, 110-450, P = 0.045; and median, 2.7%; range, 0.5-8.5 vs 0.6%; range, 0-0.8 %, P = 0.0036, respectively). No differences were observed in BAL fluid. CONCLUSION: We conclude that hyperresponsiveness to AMP in COPD is associated with airway inflammation that is characterized by increased numbers of mucosal CD8 + cells and percentages of sputum eosinophils. Hyperresponsiveness to AMP may be used as a marker of airway inflammation in COPD, but its significance in the clinical course remains to be determined.

Cartilaginous airway wall dimensions and airway resistance in cystic fibrosis lungs.

It is not clear how airway pathology relates to the severity of airflow obstruction and increased bronchial responsiveness in cystic fibrosis (CF) patients. The aim of this study was to measure the airway dimensions of CF patients and to estimate the importance of these dimensions to airway resistance using a computational model. Airway dimensions were measured in lungs obtained from CF patients who had undergone lung transplantation (n=12), lobectomy (n=1), or autopsy (n=4). These dimensions were compared to those of airways from lobectomy specimens from 72 patients with various degrees of chronic obstructive pulmonary disease (COPD). The airway dimensions of the CF and COPD patients were introduced into a computational model to study their effect on airway resistance. The inner wall and smooth muscle areas of peripheral CF airways were increased 3.3- and 4.3-fold respectively compared to those of COPD airways. The epithelium was 53% greater in height in peripheral CF airways. The sensitivity and maximal plateau resistance of the computed dose/response curves were substantially increased in the CF patients compared to COPD patients. The changes in airway dimensions of cystic fibrosis patients probably contribute to the severe airflow obstruction, and to increased bronchial responsiveness, in these patients.

Comparison of induced sputum with bronchial wash, bronchoalveolar lavage and bronchial biopsies in COPD.

It is unclear how cellular and soluble inflammatory markers in induced sputum relate to markers in lavage fluid and biopsies in chronic obstructive pulmonary disease (COPD). This was investigated and also the possible differences between subjects with COPD and healthy controls assessed. Eighteen nonatopic subjects with COPD and 11 healthy controls were studied. Sputum was induced by inhalation of hypertonic saline. The airways were lavaged, using the first 50 mL for bronchial wash (BW) and the subsequent 150 mL for bronchoalveolar lavage (BAL), and biopsies were taken from subsegmental carinae. Neutrophils were the predominant cell type in sputum in COPD (median 77.3%) but not in BW (5.5%) and BAL fluid (1.7%). Differential cell counts in sputum did not correlate with the counts in BW or BAL fluid or biopsies, whereas sputum eosinophil cationic protein (ECP) levels correlated with BW fluid ECP levels (p=0.66, p=0.007) and sputum interleukin-8 (IL-8) concentration with BAL fluid IL-8 concentration (p= 0.52, p=0.026). Subjects with COPD had a higher percentage of sputum neutrophils and eosinophils and higher concentrations of ECP and IL-8 than healthy controls. The higher percentages of eosinophils and concentrations of ECP were also seen in BW and BAL fluid. Finally, higher numbers of macrophages and eosinophils were found in biopsies. In conclusion, induced sputum is derived from a different compartment from BW and BAL fluid and biopsies. Induced sputum may be useful for studying the contribution of luminal neutrophils and eosinophils in chronic obstructive pulmonary disease.

Ongoing airway inflammation in patients with COPD who do not currently smoke.

BACKGROUND: Inflammatory changes in the airways in chronic obstructive pulmonary disease (COPD) are largely attributed to smoking, yet they may be present even if patients do not currently smoke. The differences in inflammatory cells and the factors contributing to these differences were examined in the airways of patients with COPD who do not currently smoke. METHODS: Eighteen non-atopic subjects with COPD (14 men) of mean (SD) age 62 (8) years and forced expiratory volume in one second (FEV(1)) 59 (13)% predicted and 11 non-atopic healthy subjects (eight men) of mean (SD) age 58 (8) years, FEV(1) 104 (11)% predicted were studied. Sputum induction and bronchoscopy with bronchoalveolar lavage (BAL) and biopsies were performed. RESULTS: Patients with COPD had more mucosal EG2+ cells (eosinophils) (median (range) 40 (0-190) versus 5 (0-40) cells/mm(2), p = 0.049) and CD68+ cells (1115 (330-2920) versus 590 (450-1580) cells/mm(2), p = 0.03), and a tendency towards more CD4+ but not CD8+ lymphocytes than healthy controls. Furthermore, patients with COPD had higher percentages of sputum neutrophils (77 (29-94) versus 36 (18-60)%, p = 0.001) and eosinophils (1.2 (0-8.5) versus 0.2 (0-3.1)%, p = 0.008), BAL fluid eosinophils (0.4 (0-1.7) versus 0.2 (0-0.5)%, p = 0.03), and higher concentrations of sputum eosinophilic cationic protein (ECP) (838 (115-23 760) versus 121 (35-218) ng/ml, p<0.001). Concentrations of ECP expressed per eosinophil were not higher. Patients with COPD with high mucosal EG2+ cell numbers also had high mucosal CD4+ cell numbers. Sputum eosinophilia was associated with a decrease in FEV(1)/VC and BAL fluid eosinophilia with a decrease in mucosal NP57+ cells (neutrophils). CONCLUSIONS: Subjects with COPD who do not currently smoke have increased numbers of inflammatory cells. Eosinophils are increased in number in the airways in COPD but do not seem to be activated. The increased eosinophil numbers are probably due to recruitment as a result of ongoing inflammation. Macrophages and lymphocytes may play a part in this inflammation.

[Nitric oxide and asthma]. / Stikstofmonoxide en astma.

Nitric oxide (NO) is a universal signalling molecule, involved in many physiological and pathophysiological processes, including asthmatic airway inflammation. Nitric oxide synthases (NOS) are newly identified enzyme systems active in airway epithelial cells, macrophages, neutrophils, mast cells, non-adrenergic non-cholinergic neurons, smooth muscle cells and endothelial cells. Two functional classes of NOS can be identified: the inducible form temporarily leading to large amounts of NO, and the constitutive form continuously leading to small amounts of NO. Large amounts of NO contribute to airway inflammation and killing of micro-organism, whereas small amounts of NO lead to smooth muscle relaxation. Asthmatic airway obstruction is induced by various bronchoconstricting factors (like allergens, pharmacological spasmogens, physical stimuli, infectious disease state) and is inhibited by NO. The development of specific inhibitors for the inducible form of NOS might open up a new era of antiasthmatic drugs.

Protective effect of oral terfenadine and not inhaled ipratropium on adenosine 5'-monophosphate-induced bronchoconstriction in patients with COPD.

BACKGROUND: Inhalation of adenosine 5'-monophosphate (AMP) causes bronchoconstriction in patients with asthma and in many patients with chronic obstructive pulmonary disease (COPD). In asthma, AMP-induced bronchoconstriction has been shown to be determined mainly by release of mast cell mediators, and possibly by vagal nerve stimulation, since oral terfenadine (H1-receptor antagonist) and inhaled ipratropium bromide (muscarinic receptor antagonist) both increase PC20AMP. OBJECTIVE: To investigate the mechanism of AMP-induced bronchoconstriction in COPD. METHODS: We performed a randomized, double-blind, placebo-controlled, crossover trial. Forty-four nonatopic hyperresponsive smokers with COPD (mean age +/- SD: 60+/-7 years, FEV1 61+/-12% of predicted and FEV1/VC 51+/-8%, geometric mean [GM] PC20methacholine 0.62 mg/mL and GM PC20AMP 6.77 mg/mL) participated. PC20methacholine and PC20AMP were assessed on 3 days. Before the challenges they used either 180 mg of oral terfenadine, 120 microg of inhaled ipratropium bromide, or placebo. RESULTS: GM PC20AMP was 5.44 mg/mL after placebo, increasing with 0.9 doubling concentration (P<0.0001) after terfenadine and decreasing 0.3 doubling concentration after ipratropium bromide (NS). GM PC20methacholine was 0.75 mg/mL after placebo, increasing 0.4 doubling concentration after terfenadine (NS) and 3 doubling concentrations after ipratropium bromide (P<0.0001). CONCLUSION: These findings indicate that histamine release is important in the pathophysiology of AMP-induced bronchoconstriction in smokers with COPD, whereas vagal nerve stimulation does not play a role. Therefore, PC20AMP may be a valuable tool in evaluation of treatments which affect airway histamine release.

Detection of muscarinic receptors in the human lung using PET.

UNLABELLED: The characterization of pulmonary muscarinic receptors with PET is still in its infancy. Because approximately 70% of the lungs consists of air and pulmonary muscarinic receptor densities are low, ligands with high receptor affinity are required to obtain reasonable signal-to-noise ratios on PET images. Therefore, the potent 11C-labeled muscarinic antagonist N-methyl-piperidin-4-yl 2-cyclohexyl-2-hydroxy-2-phenylacetate methiodide ([R]-VC-002) was developed. We administered this radioligand to four healthy human volunteers to examine its suitability for studying pulmonary muscarinic receptors in vivo. METHODS: [11C]VC-002 (185 MBq, specific activity > 7.4 TBq/mmol) was intravenously injected on 2 separate days, with an interval of at least 1 wk. On the first day the volunteers were not pretreated, but on the second day they received the anticholinergic glycopyrronium bromide (Robinul; 2 x 0.1 mg intravenous) 25 and 30 min before the injection of the radiopharmaceutical. C[15O]O scans (approximately 740 MBq [20 mCi] by inhalation) were acquired before the receptor scan to calculate pulmonary blood volume. RESULTS: On PET images of the thorax, the lungs were clearly visible. After the volunteer was pretreated with glycopyrronium bromide, pulmonary uptake of the radioligand was reduced to 32%+/-12% of the control value at 60 min postinjection and the lungs could no longer be seen. (R)-[11C]-VC-002 was rapidly cleared from plasma and was slowly metabolized during the time course (60 min) of the PET scan. The fraction of radioligand representing parent compound decreased from 99.9% at the time of injection to 82% at 40-60 min postinjection, both in the presence and absence of Robinul. Pulmonary tissue-to-plasma ratios, calculated on a count-per-minute-per-gram basis, reached a plateau value of 17.8+/-1.2 at 40-50 min postinjection. CONCLUSION: [11C]VC-002 appears to be suitable for in vivo studies of pulmonary cholinoceptors.

Markers of nitric oxide metabolism in sputum and exhaled air are not increased in chronic obstructive pulmonary disease.

BACKGROUND: Nitric oxide (NO) is involved in inflammation and host defence of the lung. It has been found in increased concentrations in the airways in asthmatic subjects but its levels in patients with chronic obstructive pulmonary disease (COPD) have not been investigated. A study was undertaken to determine whether markers of NO metabolism (NO in exhaled air, iNOS expression in sputum cells, and nitrite + nitrate (NO2-/NO3-) in sputum supernatant) are increased in subjects with COPD, and whether they correlate with inflammatory indices in induced sputum. The associations of these markers with smoking were also assessed. METHODS: Sixteen subjects with COPD (median age 66 years, median forced expiratory volume in one second (FEV1) 63% predicted, eight current smokers) and 16 healthy subjects (median age 63 years, median FEV1 113% predicted, eight current smokers) participated in the study. NO was measured during tidal breathing and sputum was induced by inhalation of hypertonic saline. RESULTS: No differences were observed between subjects with COPD and healthy controls in exhaled NO excretion rate (median 5.15 and 6.25 nmol/min), sputum macrophage iNOS expression (14% and 12%), and sputum supernatant NO2-/NO3- (46 and 73 microM). NO in exhaled air correlated with the percentage of sputum eosinophils in patients with COPD (rho = 0.65, p = 0.009) but not in healthy individuals. Exhaled NO and supernatant NO2-/NO3- levels were lower in healthy smokers than in healthy non/ex-smokers. CONCLUSIONS: Our findings indicate that NO metabolism is not increased in patients with stable COPD. The close association between exhaled NO levels and sputum eosinophils suggests a role for NO in airway inflammation in COPD. Studies performed during exacerbations may clarify this role.

Respiratory ammonia output and blood ammonia concentration during incremental exercise.

The aim of this study was to investigate whether the increase of ammonia concentration and lactate concentration in blood was accompanied by an increased expiration of ammonia during graded exercise. Eleven healthy subjects performed an incremental cycle ergometer test. Blood ammonia, blood lactate and the amount of expired ammonia were measured until 30 minutes post exercise. The expired air was guided through a flow chamber filled with a sulphuric acid solution to trap the expired ammonia. Blood ammonia, blood lactate increased more than proportionally and the amount of expired ammonia (in micromol/min) increased exponentially with the workload. Post-exercise the amount of expired ammonia decreased within a few minutes back to pre-exercise levels while the concentrations of lactate and ammonia in blood decreased much more slowly and were still elevated after 30 minutes of recovery. We conclude that the more than proportional increase of ammonia and lactate during graded exercise, is accompanied with an exponential increase of expired ammonia output. Faster and more accurate ammonia gas detection techniques are necessary to quantify more precisely the respiratory ammonia output during graded exercise.

Cytomegalovirus pneumonitis after kidney transplantation is not caused by plugging of cytomegalic endothelial cells only.

In addition to life-threatening pneumonia, cytomegalovirus (CMV) may also cause subclinical pulmonary dysfunction after kidney transplantation. To investigate the role of plugging of cytomegalic endothelial cells in the pulmonary capillary bed, we prospectively determined specific carbon monoxide diffusion capacity (KCOc) and its components: the pulmonary diffusing membrane factor (Dm) and pulmonary capillary blood volume (Vcap) before and during CMV infection in 13 kidney transplant recipients and 13 controls. During CMV infection, mean KCOc decreased significantly by 28 % of the initial value (mean KCOc 79 vs 109; P < 0.005 ) due to a decrease in both Vcap and Dm. The KCOc in controls showed a significantly smaller decrease due to a slightly lower Vcap. We conclude that kidney transplant recipients with CMV infection have significant pulmonary diffusion disturbances due to a combination of lower Vcap and lower Dm. The most likely explanation for this phenomenon is a local inflammatory process due to CMV and not plugging of cytomegalic endothelial cells only.

Characterisation of beta2-adrenoceptors, using the agonist [11C]formoterol and positron emission tomography.

The agonist radioligand N-[2-hydroxy-5-[1-hydroxy-2-[[2-(4-[11C]-methoxyphenyl)-1-methylethyl]am ino]ethyl]phenyl]formamide ([11C]formoterol) was synthesised in order to test its ability to visualise pulmonary beta2-adrenoceptors in vivo, with positron emission tomography (PET). Formoterol was labelled via reaction of a dibenzyl-protected precursor with [11C]CH3I. Subsequent deprotection with Pd/C and H2 yielded [11C]formoterol in 5-15% (corrected for decay) and the specific activity ranged from 5.5-22.2 TBq mmol (150-600 Ci mmol(-1)), 60-70 min after end of bombardment. Biodistribution studies with [11C]formoterol were performed in male Wistar rats which were either untreated or predosed with (D,L)-propranolol hydrochloride (2.5 mg kg(-1), beta-adrenoceptor antagonist), erythro-DL-1-(7-methylindan-4-yloxy)-3-isopropylaminobuta n-2-ol hydrochloride (ICI 118551, 0.15 mg kg(-1), beta2-adrenoceptor antagonist), isoprenaline (15 mg kg(-1), non-subtype selective beta-adrenoceptor agonist) or (+/-)-(2-hydroxy-5-[2-((2-hydroxy-3-(4-((1-methyl-4-trifluoromethyl)1H-i midazol-2-yl-)phenoxy)propyl)amino)ethoxy]benzamide)monomethane sulfonate (CGP 20712A, 0.15 mg kg(-1), beta1-adrenoceptor antagonist). Lungs, heart, liver and plasma were analysed for radioactive metabolites. The kinetics of [11C]formoterol in the lungs of male Wistar rats were investigated by means of a dynamic PET study. The biodistribution studies showed significant specific binding in tissues known to contain beta2-adrenoceptors (lungs, spleen, and heart). Binding in these organs was blocked by ICI 118551 and isoprenaline, but not by CGP 20712A. [11C]Formoterol was rapidly metabolised in rats but lungs and heart did not substantially take up the labelled metabolites. The binding of [11C]formoterol in various tissues of rats is consistent with the beta2-selectivity of formoterol. Whether [11C]formoterol selectively binds to the high affinity state of beta2-adrenoceptors remains to be elucidated. [11C]Formoterol is potentially useful for studying beta2-adrenoceptors with PET and this radioligand may provide new insights in the mechanisms underlying prolonged sympathomimetic action.

Nitric oxide measured with single-breath and tidal-breathing methods in asthma and COPD.

Nitric oxide (NO) can be measured in exhaled air with the single-breath (SB) and tidal-breathing (TB) methods. To allow comparison between different laboratories, a European Respiratory Society task force recently reported guidelines for standardization of both methods. To facilitate comparison between laboratories further, this study investigated whether there is a difference between NO values measured with SB and TB methods in subjects with asthma or chronic obstructive pulmonary disease (COPD), and in healthy subjects. Moreover, the differences between groups were studied and the influence of smoking in asthma was assessed. Sixteen atopic nonsmoking asthmatics, 16 atopic currently smoking asthmatics, 16 nonatopic nonsmoking healthy controls, 16 nonatopic exsmokers with COPD and 16 nonatopic exsmoking healthy controls were studied. NO concentrations differed substantially between both methods. Mean NO concentrations were higher with the SB than with the TB method in nonsmoking and in smoking asthmatics and especially so with the higher NO values. Furthermore, NO values with both methods were higher in nonsmoking asthmatics than in nonsmoking healthy subjects. NO was not significantly different between exsmokers with COPD and healthy exsmokers. In conclusion nitric oxide values of the single-breath and tidal-breathing methods are not interchangeable. Both methods can be used to measure differences between groups.

Exhaled nitric oxide is higher both at day and night in subjects with nocturnal asthma.

Nitric oxide in exhaled air is thought to reflect airway inflammation. No data have been reported so far on circadian changes in NO in subjects with nocturnal asthma. To determine whether exhaled NO shows a circadian rhythm inverse to the circadian rhythm in airway obstruction in subjects with nocturnal asthma, we conducted a study involving six healthy controls, eight individuals without nocturnal asthma (4-h to 16-h variation in peak expiratory flow [PEF] <= 15%), and six individuals with nocturnal asthma (4-h to 16-h PEF variation > 15%). Smoking, use of corticosteroids, and recent respiratory infections were excluded. NO concentrations were measured at 12, 16, 20, and 24 h, and at 4, 8, and 12 h of the next day, using the single-breath method. At the same times, FEV1 and PEF were also measured. Mean NO concentrations were significantly higher in subjects with nocturnal asthma than in subjects without nocturnal asthma, and higher in both groups than in healthy controls at all time points. Mean exhaled NO levels over 24 h correlated with the 4-h to 16-h variation in PEF (r = 0.61, p < 0.01). Exhaled NO did not show a significant circadian variation in any of the three groups as assessed with cosinor analysis, in contrast to the FEV1 in both asthma groups (p < 0.05). At 4 h, mean +/- SD NO levels were higher than at 16 h in subjects with nocturnal asthma; at 50 +/- 20 ppb versus 42 +/- 15 ppb (p < 0.05); other measurements at all time points were similar. Differences in NO and FEV1 from 4 h to 16 h did not correlate with one another. We conclude that subjects with nocturnal asthma exhale NO at higher levels both at night and during the day, which may reflect more severe diurnal airway-wall inflammation. A circadian rhythm in exhaled NO was not observed. NO levels did not correspond to the circadian rhythm in airway obstruction. The small increase in NO at 4 h may indicate an aspect of inflammation, but it is not associated with increased nocturnal airway obstruction.

Short-term treatment with budesonide does not improve hyperresponsiveness to adenosine 5'-monophosphate in COPD.

The role of inhaled corticosteroids in the treatment of chronic obstructive pulmonary disease (COPD) is unclear. We investigated the effects of budesonide on airway hyperresponsiveness (AHR) to methacholine (MCh) and adenosine 5'-monophosphate (AMP), to which we hypothesized the existence of greater sensitivity. Additionally, we studied the effects of budesonide on terfenadine and ipratropium bromide and on serum levels of interleukin-8 (IL-8) and histamine. Forty-four hyperresponsive smokers with moderate to severe COPD participated in the study. MCh and AMP challenges were given on three study days, after pretreatment with single doses of ipratropium bromide, terfenadine, or placebo. Thereafter, subjects were randomized to 6 wk treatment with either 1,600 microg budesonide or placebo, and the same three study days were repeated. Budesonide, as compared with placebo, did not significantly change PC20AMP, PC20MCh, or FEV1 after placebo pretreatment. Budesonide increased PC20MCh after ipratropium bromide pretreatment, from 5.05 to 10.20 mg/ml (p = 0.036). Budesonide decreased serum IL-8 from 9.2 +/- 3.7 to 6.2 +/- 2.1 pg/ml (p < 0.001). We conclude that AMP did not elicit greater sensitivity than MCh in assessing short-term effects of budesonide on AHR in smokers with COPD. We suggest that long-term treatment with inhaled corticosteroids might be beneficial, by reducing neutrophil load in the airways and improving the action of anticholinergic drugs.

Water vapour and carbon dioxide decrease nitric oxide readings.

Measurement of nitric oxide levels in exhaled air is commonly performed using a chemiluminescence detector. However, water vapour and carbon dioxide affect the chemiluminescence process. The influence of these gases at the concentrations present in exhaled air, has not yet been studied. For this in vitro study, mixtures of 50, 100 and 200 parts per billion (ppb) NO in air were prepared and fed into the NO analyser either directly or bubbled through water. Mixtures with CO2 were prepared by adding 0-10% CO2 to the diluent air. We found a significant decrease in NO readings in the water-saturated samples compared to the dry gas (p < 0.001), strongly dependent on the partial pressure of water. NO levels in exhaled air (mean 10 +/- 2 ppb) showed a decrease of 17 +/- 3% when water vapour was not absorbed. From the experiments with CO2 we found a decrease in NO reading of 1.04 +/- 0.07% per volume CO2 (%). Presence of water vapour, thus, leads to a systematic underestimation of NO levels. Insertion of a water absorber might, therefore, be advantageous. The influence of CO2 concentrations in the normal respiratory range is negligible. With high expiratory CO2 levels as applied in permissive hypercapnia, the effects may be substantial.