Maximal Mid-expiratory Flow Rate Research Articles

Changes in pulmonary function in patients with chronic renal failure after successful renal transplantation

Pulmonary function abnormalities have been described in patients with chronic renal failure. There are very few longitudinal studies showing the effect of renal transplantation on pulmonary function. We aimed to study the effects of renal failure on pulmonary functions and to observe the changes following successful renal transplantation. Patients with end-stage renal failure (n=25) of various etiologies who presented to the renal transplant unit of a teaching hospital were included in this prospective, longitudinal study. Patients with a prior history of pulmonary disease and chronic smokers were excluded. Pulmonary function tests were performed and blood gases evaluated before and 6 months after successful renal transplantation. Most patients showed pulmonary function abnormalities which improved significantly after transplantation. The mean vital capacity increased from 2.89 (95% CI 2.63-3.15) l pre-transplantation to 3.32 (95% CI 3.09-3.54) l post-transplantation (p<0.001), indicating that subjects had a restrictive pulmonary function defect which improved after transplantation. The large airways were normal, as evidenced by normal forced expiratory volume in the first second:forced vital capacity ratios. There was significant small airways dysfunction, as shown by low maximal mid-expiratory flow rates, which tended to improve after renal transplantation (p=0.013). There was also a highly significant (p<0.001) improvement in maximal voluntary ventilation (MVV) after transplantation. The MVV test is a composite test which measures all aspects of pulmonary function, including respiratory muscle strength. However, not all patients achieved normal pulmonary function due to uremia-induced irreversible pre-transplantation changes. Pulmonary function abnormalities are common in patients with chronic renal failure but can be significantly ameliorated following successful renal transplantation.

Reduced Lung Function at Birth and the Risk of Asthma at 10 Years of Age

Reduced lung function in early infancy has been associated with later obstructive airway diseases. We assessed whether reduced lung function shortly after birth predicts asthma 10 years later. We conducted a prospective birth cohort study of healthy infants in which we measured lung function shortly after birth with the use of tidal breathing flow-volume loops (the fraction of expiratory time to peak tidal expiratory flow to total expiratory time [t(PTEF)/t(E)]) in 802 infants and passive respiratory mechanics, including respiratory-system compliance, in 664 infants. At 10 years of age, 616 children (77%) were reassessed by measuring lung function, exercise-induced bronchoconstriction, and bronchial hyperresponsiveness (by means of a methacholine challenge) and by conducting a structured interview to determine whether there was a history of asthma or current asthma. As compared with children whose t(PTEF)/t(E) shortly after birth was above the median, children whose t(PTEF)/t(E) was at or below the median were more likely at 10 years of age to have a history of asthma (24.3% vs. 16.2%, P=0.01), to have current asthma (14.6% vs. 7.5%, P=0.005), and to have severe bronchial hyperresponsiveness, defined as a methacholine dose of less than 1.0 micromol causing a 20% fall in the forced expiratory volume in 1 second (FEV1) (9.1% vs. 4.9%, P=0.05). As compared with children whose respiratory-system compliance was above the median, children with respiratory compliance at or below the median more often had a history of asthma (27.4% vs. 14.8%; P=0.001) and current asthma (15.0% vs. 7.7%, P=0.009), although this measure was not associated with later measurements of lung function. At 10 years of age, t(PTEF)/t(E) at birth correlated weakly with the maximal midexpiratory flow rate (r=0.10, P=0.01) but not with FEV1 or forced vital capacity. Reduced lung function at birth is associated with an increased risk of asthma by 10 years of age.

A Comparative Study Between Preoperative and Postoperative Pulmonary Functions and Diaphragmatic Movements in Congenital Craniovertebral Junction Anomalies

Respiratory dysfunctions in patients with craniovertebral junction (CVJ) anomalies may occur due to compression of brainstem affecting the respiratory centers, and weakening of the muscles of respiration. We assessed pulmonary functions [forced vital capacity (FVC), forced expiratory volume in first second (FEV1), maximum mid-expiratory flow rate (FEF25%-75%), FEV1%], mouth pressures (maximum inspiratory pressure, maximum expiratory pressure), and diaphragmatic movements in 30 patients of CVJ anomalies and compared them with their mean predictive values. These parameters were also assessed in the postoperative period. It was found that the mean values of FVC, FEV1, and FEF25%-75% were significantly lower (P<0.001) than their mean predictive values (2.4+/-0.8 L, 2.0+/-0.7 L, 2.5+/-0.9 L vs. 3.7+/-0.9 L, 3.2+/-0.7 L, and 3.4+/-0.7 L, respectively). In the postoperative period there was significant reduction (P<0.05) in all these parameters (2.2+/-0.8 L, 1.7+/-0.7 L, and 2.1+/-0.8 L, respectively). The postoperative FEV1% was 78.8% compared with the preoperative value of 85.7%. A restrictive pattern of lung disease was observed which persisted in the postoperative period. The postoperative maximum inspiratory pressure and maximum expiratory pressure were comparable to their preoperative values (47.9+/-19.6 and 47.0+/-16.7 cmH2O vs. 42.6+/-17.3 and 43.9+/-18.2 cmH2O, respectively). Similarly, the diaphragmatic movements were also comparable to the preoperative values, both during quiet and deep breathing (13.7+/-3.9 and 38.0+/-9.3 mm vs. 13.8+/-3.9 and 39.0+/-9.1 mm, respectively). There was no improvement of pulmonary functions in the early postoperative period. However, a long-term follow-up is needed to determine subsequent changes of these parameters.

Volatile Organic Compounds and Pulmonary Function in the Third NationalHealth and Nutrition Examination Survey, 1988–1994

BackgroundVolatile organic compounds (VOCs) are present in much higher concentrations indoors, where people spend most of their time, than outdoors and may have adverse health effects. VOCs have been associated with respiratory symptoms, but few studies address objective respiratory end points such as pulmonary function. Blood levels of VOCs may be more indicative of personal exposures than are air concentrations; no studies have addressed their relationship with respiratory outcomes.ObjectiveWe examined whether concentrations of 11 VOCs that were commonly identified in blood from a sample of the U.S. population were associated with pulmonary function.MethodsWe used data from 953 adult participants (20–59 years of age) in the Third National Health and Nutrition Examination Survey (1988–1994) who had VOC blood measures as well as pulmonary function measures. Linear regression models were used to evaluate the relationship between 11 VOCs and measures of pulmonary function.ResultsAfter adjustment for smoking, only 1,4-dichlorobenzene (1,4-DCB) was associated with reduced pulmonary function. Participants in the highest decile of 1,4-DCB concentration had decrements of −153 mL [95% confidence interval (CI), −297 to −8] in forced expiratory volume in 1 sec and −346 mL/sec (95% CI, −667 to −24) in maximum mid-expiratory flow rate, compared with participants in the lowest decile.ConclusionsExposure to 1,4-DCB, a VOC related to the use of air fresheners, toilet bowl deodorants, and mothballs, at levels found in the U.S. general population, may result in reduced pulmonary function. This common exposure may have long-term adverse effects on respiratory health.

Same Efficacies of Ipratropium and Salbutamol in Reversing Methacholine-Induced Bronchoconstriction

Efficacy of salbutamol (S) was compared to that of ipratropium (I) or to their association, after methacholine challenge testing (MCT). MCT was performed in 4 groups of 10 patients suspected to suffer from asthma; mean changes in FEV1, maximal midexpiratory flow rate (MMFR), and airway resistance (Raw) were the same in all groups. After MCT, the group 1 patients inhaled S and then I, 10 min later; both drugs were given in the reverse order to the group 2 patients. The group 3 patients inhaled a mixture of both drugs just after MCT; the group 4 patients were not given any bronchodilator till the 20th min after MCT, when they inhaled S. Short-term (10 min) bronchodilator effects of S, I or S + I on spirometric variables were of the same magnitude and Raw returned to its baseline value. Further improvement (10–20 min) in FEV1 was mainly due to spontaneous recovery, whereas further increase in MMFR was due also to bronchodilator actions of drugs. It is concluded that ipratropium could be proposed as an alternative bronchodilator to salbutamol after MCT.

Editorial: Small Airways Disease and Asthma

Editorial: Small Airways Disease and Asthma

Gender, Environmental Tobacco Smoke, and Pulmonary Function in Rural Children and Adolescents: The Humboldt Study

We examined the gender-related association between household exposure to environmental tobacco smoke (ETS) and pulmonary function among 862 children and adolescents aged 6 to 17 years living in the town of Humboldt, Saskatchewan, in 1993. Pulmonary function tests included forced vital capacity (FVC), forced expiratory volume in one second (FEV1), maximum mid-expiratory flow rate (FEF25-75), and flow rates at 75%, 50%, and 25% of vital capacity (Vmax75, Vmax50, and Vmax25). Each pulmonary function test variable was regressed on age, height, weight, and their quadratic and cubic polynomials, with the terms significant at the alpha level of 0.10 being retained. Residuals for the pulmonary function test variables, which are the differences between the observed and predicted values, were calculated. Estimations of ETS exposure were parental smoking status, number of household smokers, total daily cigarette consumption, and number of cigarettes smoked daily at home by household members. Maternal smoking status was significantly related to residual FEF25-75, Vmax75, Vmax50, and Vmax25. Number of household smokers and daily cigarette consumption by household members were significantly associated with FEV1, FEF25-75, Vmax75, Vmax50, and Vmax25, and the association between ETS exposure and pulmonary function was stronger in girls than in boys. Interaction of gender and number of cigarettes smoked daily at home was significantly related to FEF25-75, Vmax75, Vmax50, and Vmax25 among the non-smoking subjects. We concluded that ETS exposure had a larger effect on pulmonary function in girls than in boys.

Effects of iohexol on ventilatory functions in patients undergoing diagnostic coronary angiography

Adverse respiratory reactions have been reported with intravascular radiographic contrast media. The aim of the present study is to assess the effects of iohexol on pulmonary functions in patients undergoing diagnostic coronary angiography (CA). 30 patients enrolled in the study. The respiratory functions of the patients were measured at three different stages during angiography (before, immediately after and 2 h later) and arterial blood gas analyses were performed at six stages during CA (before, immediately after the insertion of angiography catheter, 2 min after the injection of contrast agent, at the end of angiography, an hour and 2 h after angiography). A single, experienced angiographer performed the angiography procedures via radial artery route. Totally six multiple angled views of the left and right coronary arteries were recorded in all patients by hand injection. None of the patients were performed ventriculography. Angiography caused significant reduction in forced expiratory volume in 1 sec [FEV1] (from 103 +/- 15 to 95 +/- 17, p < 0.01), forced vital capacity [FVC] (from 99 +/- 13 to 95 +/- 18, p < 0.05) and maximum mid-expiratory flow rate [MMF] (from 95 +/- 33 to 84 +/- 29, p < 0.01) whereas there were no significant changes in the mean FEV1/FVC ratios at different stages of angiography. Statistically significant decrease in PaO2 (from 91 +/- 10 to 85 +/- 13 mmHg, p < 0.01) and arterial O2 saturation (from 97 +/- 1% to 96 +/- 1%, p < 0.01) were also observed. Data in present study showed a clinically insignificant but statistically significant restrictive impairment in pulmonary functions. Diagnostic CA using iohexol decreases ventilatory functions in a small but significant extent in patients without any overt pulmonary disease.

A comparison of lung function methods for assessing dose-response effects of salbutamol.

Pulmonary function methods which are able to detect small pharmacological effects may be useful for assessing the full dose-response curve of bronchodilatators. We compared the ability of impulse oscillometry (R5, R20, X5, RF), plethysmography (sGaw) and spirometry [forced expiratory volume in 1 s (FEV(1)), maximal mid expiratory flow rate (MMEF)] to measure the dose-response effects of salbutamol in 12 healthy subjects, 12 mild asthmatics (mean FEV(1) 96% predicted) and 12 moderate asthmatics (mean FEV(1) 63% predicted). The techniques were performed twice to assess variability. Then salbutamol 10, 20, 100, 200 and 800 microg was administered. The sensitivity of the methods were compared by determining the lowest dose that caused changes greater than variability. In healthy subjects significant changes (p < or = 0.05) were observed only in FEV(1) (4.1%) and MMEF (14.6%) at 100 microg and sGaw (25.6%) and R20 (8.3%) at 200 microg. In mild asthmatics significant changes were observed in sGaw (15.9%) at 10 microg, X5 (23%), RF (20.3%) and MMEF (15.7%) at 20 microg, R5 (13.9%) and R20 (9.4%) at 100 microg and FEV(1) (7.1%) at 200 microg. All measurements except R20 demonstrated significant changes at 10 micro g in moderate asthmatics. The most sensitive test for assessing bronchodilatation is different in healthy subjects and asthmatics, and varies with severity of airflow obstruction.

Airways obstruction in survivors of thoracoplasty: reversibility is greater in non-smokers.

Before the advent of antituberculous chemotherapy, thoracoplasty (TPL) was the definitive form of therapy for cavitary pulmonary tuberculosis. This study aimed to characterize the late functional sequelae of TPL, and to establish the degree of reversibility of any consequent airway obstruction. Pulmonary function was studied in 21 long-term (mean 35 years) survivors of TPL between the years 1990-2001. A mixed obstructive/restrictive defect was found in this patient cohort. After inhalation of bronchodilator, marginal increases in FEV(1) and FVC and marginal decreases in FRC, RV and TLC were observed. Maximum mid-expiratory flow rate was severely reduced (28.8% of predicted), but reversibility after inhaled beta(2)-agonist was highest for this parameter of pulmonary function (mean 11%). Smokers had a higher RV (P = 0.04), suggesting hyperinflation, while non-smokers had a larger increase in FEV(1)/FVC ratio postbronchodilator (P = 0.004), suggesting more marked reversibility of airways obstruction in this group. Long-term survivors of TPL have an obstructive as well as a restrictive ventilatory defect. These patients have partial reversibility of the obstructive defect. The degree of reversibility found suggests that bronchodilator therapy may help these patients.

Pulmonary Function, Diffusing Capacity, and Inflammation in Healthy and Asthmatic Subjects Exposed to Ultrafine Particles

Particulate air pollution is associated with asthma exacerbations and increased morbidity and mortality from respiratory causes. Ultrafine particles (particles less than 0.1 μ m in diameter) may contribute to these adverse effects because they have a higher predicted pulmonary deposition, greater potential to induce pulmonary inflammation, larger surface area, and enhanced oxidant capacity when compared with larger particles on a mass basis. We hypothesized that ultrafine particle exposure would induce airway inflammation in susceptible humans. This hypothesis was tested in a series of randomized, double-blind studies by exposing healthy subjects and mild asthmatic subjects to carbon ultrafine particles versus filtered air. Both exposures were delivered via a mouthpiece system during rest and moderate exercise. Healthy subjects were exposed to particle concentrations of 10, 25, and 50 μ g/m3, while asthmatics were exposed to 10 μ g/m3. Lung function and airway inflammation were assessed by symptom scores, pulmonary function tests, and airway nitric oxide parameters. Airway inflammatory cells were measured via induced sputum analysis in several of the protocols. There were no differences in any of these measurements in normal or asthmatic subjects when exposed to ultrafine particles at concentrations of 10 or 25 μ g/m3. However, exposing 16 normal subjects to the higher concentration of 50 μ g/m3 caused a reduction in maximal midexpiratory flow rate (−4.34 ± 1.78% [ultrafine particles] vs. +1.08 ± 1.86% [air], p =. 042) and carbon monoxide diffusing capacity (−1.76 ± 0.66 ml/min/mm Hg [ultrafine particles] vs. −0.18 ± 0.41 ml/min/mm Hg [air], p =. 040) at 21 h after exposure. There were no consistent differences in symptoms, induced sputum, or exhaled nitric oxide parameters in any of these studies. These results suggest that exposure to carbon ultrafine particles results in mild small-airways dysfunction together with impaired alveolar gas exchange in normal subjects. These effects do not appear related to airway inflammation. Additional studies are required to confirm these findings in normal subjects, compare them with additional susceptible patient populations, and determine their pathophysiologic mechanisms.

Chronic pulmonary thromboembolism. Air trapping on computed tomography and correlation with pulmonary function tests.

We evaluated lung attenuation on inspiratory/expiratory computed tomography (CT) and spiral CT angiography (CTA) from patients with chronic pulmonary embolism and correlated the CT findings with pulmonary function test (PFT) results. We retrospectively reviewed 9 patients with chronic embolism (mean age, 62.3 years; 5 women and 4 men). Paired inspiratory, expiratory CT and matching CTA images were reviewed, and lung attenuation was evaluated in each segment. Lower attenuation on inspiratory images and air trapping on expiratory images were subjectively assessed and correlated with PFT results. The relationship between the presence of clot and lung attenuation was evaluated. Nine age-matched normal subjects served as controls. Lower attenuation with mosaic perfusion and air trapping were identified in 6 and 9 patients, respectively (mean scores, 8.1 and 11.3, respectively). Air trapping was identified in 19 (42.2%) of 45 segments with lower attenuation on inspiratory images, but was also noted in 31 segments with normal inspiratory attenuation. Air trapping was associated with the presence of proximal arterial stenosis (P<0.01), and the area showed less contrast enhancement than the adjacent lung (P<0.05). Extent of air trapping correlated inversely with PFT parameters of peripheral airway obstruction such as maximum mid-expiratory flow rate (r=-0.86, P=0.003). On the other hand, extent of mosaic perfusion did not correlate with PFT. Air trapping is commonly seen in chronic embolism and is found in areas of relative hypoperfusion. The extent of air trapping correlates with parameters of peripheral airway obstruction.

Pleuropulmonary complications of esophageal variceal sclerotherapy with absolute alcohol.

Esophageal variceal sclerotherapy (EVS) is an effective means of controlling variceal hemorrhage. However, it causes a wide variety of local and systemic complications. The present study was performed to document pleuropulmonary complications of EVS with absolute alcohol. Twenty-six patients of portal hypertension of different etiologies were subjected to EVS with absolute alcohol. Baseline arterial blood gas analysis (PaO2, PaCO2, pH, HCO3, SaO2), chest X-ray and pulmonary function tests (forced expiratory volume at 1 s (FEV1), forced expiratory vital capacity (FVC), FEV1/FVC, maximum mid-expiratory flow rate (MMFR), and peak expiratory flow rate (PEFR)) were performed 4-6 h before the first session of EVS. These investigations were repeated within 24 h of EVS. Patients were asked to maintain a symptom diary and to record symptoms such as fever, chest pain, dysphagia and dyspnea during the study period. Ten patients (38.46%) had chest pain and four patients (15.68%) had fever after sclerotherapy. Eight patients (30.54%) complained of dyspnea and six patients (23.08%) developed pleural effusion. There was a significant decline in FVC and FEV1 after EVS as compared with baseline values. However, FEV1/FVC ratio, MMFR and PEFR did not have any significant change. Chest pain (38.46%), dyspnea (30.54%) and fever (15.68%) were the common symptoms after EVS while chest X-ray showed pleural effusion in 23.08%. Pulmonary function tests revealed a significant decline in FEV1 and FVC without change in FEV1/FVC ratio after EVS, suggesting a restrictive type of defect.

Comparison of Maximal Midexpiratory Flow Rate and Forced Expiratory Flow at 50% of Vital Capacity in Children

The mid-portion of the maximal expiratory flow-volume (MEFV) curve is often described by values of the mean forced expired flow as lung volume decreases from 75% to 25% of vital capacity (ie, forced expiratory flow, midexpiratory phase [FEF(25-75)]). It is common practice to report also forced expired flow at 50% of vital capacity (FEF(50)). To investigate whether FEF(50) and FEF(25-75) are highly correlated or whether the difference between them reflects a degree of airways obstruction. Also, we wanted to investigate the correlation between the two in cases of irregularly shaped MEFV curves (ie, "saw-toothing"). Analysis of the correlation between FEF(50) and FEF(25-75) in a single determination. We assessed the relationship between the FEF(50)/FEF(25-75) ratio and the degree of airways obstruction, as reflected by other traditional parameters such as FEV(1), FEV(1)/FVC ratio, and specific airway conductance (SGaw). There were 1,350 forced expiratory maneuvers performed by children with a broad range of pulmonary abnormalities. FEF(50) correlated with FEF(25-75) as follows: FEF(50) (L/s) = 0.041 + 1.136*FEF(25-75)(L/s); r(2) = 0.956; standard error of the estimate = 0.013; p < 0.0001. The FEF(50)/FEF(25-75) ratio remained stable and did not correlate with FEV(1) (r = 0.12), FEV(1)/FVC ratio (r = 0.11), or SGaw (r = 0.02; difference not significant). The correlation between FEF(25-75) and FEF(50) was similar for both the smooth curve (r = 0.97) and the irregular curve (r = 0.96). Although not identical, FEF(25-75) and FEF(50) are highly correlated, and the ratio of the two is fairly constant. Therefore, the practice of reporting both of them is unnecessary. We suggest that it is reasonable to prefer FEF(50).

The effect of ipratropium bromide on intraocular pressure in patients with chronic obstructive pulmonary disease: an open-label study

Background: After smoking cessation, bronchodilation with anticholinergics and beta 2-agonists is the keystone of pharmacologic therapy for symptomatic chronic obstructive pulmonary disease (COPD). For patients who fail to get relief from a drug delivered via a metered-dose inhaler (MDI) plus spacer, or for acute exacerbations in patients who are unable to use an MDI, a nebulized solution (NS) usually is preferred. Although ipratropium bromide (IB) has a low incidence of adverse events, anticholinergic drugs are known to produce side effects such as urinary retention, constipation, drying of secretions, and precipitation of glaucoma. Objective: In this open-label study, we aimed to assess the acute effects of IB on intraocular pressure (IOP) and tolerability of administration of IB by MDI and NS in patients with COPD and baseline values of IOP that were within normal limits. Methods: Eligible patients were aged >40 years and had a cigarette smoking history of >20 pack-years (ie, packs/d × years of smoking), a clinical history of COPD, and a ratio of forced expiratory volume in 1 second to slow vital capacity (FEV 1/VC) <89% predicted value. After baseline pulmonary function testing (PFT), IOP measurements by Goldmann applanation tonometry were performed. PFT measurements were repeated at 15 and 120 minutes after drug inhalation, and IOP measurements were repeated 120 minutes after drug inhalation. Doses were administered on 3 consecutive mornings: placebo on day 1, MDI IB 40 μg on day 2, and NS IB 250 μg on day 3. Results: Measurements are expressed as mean ± SD. Twenty-one stable patients with COPD (all men; mean age, 60.95 ± 7.90 years; mean smoking history, 47.24 ± 17.62 pack-years) were selected from a university hospital outpatient population. On MDI and NS test days (days 2 and 3), respectively, mean baseline FEV 1 measurements were 1.30 ± 0.62 L (42.74% ± 20.11% predicted value) and 1.23 ± 0.58 L (41.16% ± 18.51% predicted value); mean baseline IOPs for the MDI group were 14.24 ± 2.61 mm Hg and 14.00 ± 2.51 mm Hg (right and left eyes, respectively) and for the NS group were 14.57 ± 2.52 mm Hg and 14.00 ± 2.63 mm Hg (right and left eyes, respectively). Although improvements in forced VC, FEV 1, and maximal mid-expiratory flow rate were significant at 15 and 120 minutes for both delivery methods ( P < 0.01 for both delivery methods at both times), no significant increase in IOP was found. Conclusion: The single-dose administration of MDI and NS formulations of IB at doses producing bronchodilation had no significant effect on IOP in this study population.

The Effect of Heliox-Driven Bronchodilator Aerosol Therapy on Pulmonary Function Tests in Patients with Asthma

To compare the effects of heliox-driven (He 80:O2 20) to air-driven (N 79:O2 21) β2-agonist aerosol therapy on pulmonary function tests (PFTs) in patients with asthma, a prospective randomized crossover study was undertaken in the asthma clinic of the university-affiliated county hospital in Houston, TX. Thirty-one patients (22 female, age range 18–44) with clinically stable asthma consented. All patients were studied on two different days with both heliox and air as driving gas, therefore serving as their own controls. The PFTs including forced expiratory volume in 1 sec (FEV1), forced vital capacity (FVC), maximal mid-expiratory flow rate (FEF25–75), and maximal expiratory flow rate (FEFmax) were obtained while breathing ambient air at baseline and 30 min after the bronchodilator treatment. Albuterol sulfate 2.5 mg was nebulized with either heliox or compressed air at 8 L/min for 8 min. When heliox was used as driving agent, additional heliox was delivered via a closed system and no entrainment of external air was allowed. Primary outcome measure was absolute change in FEV1 (ΔFEV1). There were no statistically significant differences in baseline PFTs on the two days of the study. All patients had good bronchodilator response (≥12% improvement in FEV1) with either driving gas. The ΔFEV1 after heliox-driven bronchodilator (HDBD) and air-driven bronchodilator (ADBD) were 0.68±0.38 L/sec (CI: 0.54–0.82) vs. 0.51±0.26 L/sec (CI: 0.42–0.60), respectively (p=0.004). The ΔFEV1 with HDBD was 49±90% (range −36% to 433%) more than ADBD. A subgroup analysis showed this was largely due to better response rates in patients with moderate to severe obstruction. There was more improvement in both FVC and FEFmax with HDBD than ADBD (p<0.05). The changes in FEF25–75 were similar. We conclude that HDBD therapy improves FEV1, FVC, and FEFmax significantly more than ADBD in patients with asthma. Further large randomized studies are needed to better characterize responders and the impact on clinical outcomes.

Centrilobular Nodules Correlate With Air Trapping in Diffuse Panbronchiolitis During Erythromycin Therapy

Low-dose erythromycin therapy improves airflow limitation and airway inflammation in patients with diffuse panbronchiolitis (DPB). However, to our knowledge there has been no study to determine whether physiologic improvement during erythromycin therapy correlates with radiologic findings. To clarify whether improvement in pulmonary function correlates with specific changes on chest CT. The relationship between five CT findings and five pulmonary function parameters was evaluated before and 3 months after low-dose erythromycin therapy in 24 patients with DPB retrospectively. After erythromycin therapy, the predicted percentage of vital capacity (%VC; 87.0 +/- 3.07% vs 98.9 +/- 3.39%; p = 0.00006) and 50% of the maximum midexpiratory flow rate of FVC (1.41 +/- 0.26 L/s vs 1.61 +/- 0.27 L/s; p = 0.03) significantly increased, and the residual volume/total lung capacity ratio (RV/TLC%; 44.5 +/- 1.93% vs 40.7 +/- 1.83%; p = 0.0019) significantly decreased, but the FEV(1) to FVC ratio and 25% of the maximum expiratory flow rate of FVC did not. In five CT findings, centrilobular nodules (3.7 +/- 0.4 vs 1.5 +/- 0.3; p = 0.0001), peripheral bronchiolar wall thickness (3.8 +/- 0.3 vs 2.6 +/- 0.4; p = 0.0007), and peripheral bronchiolectasis (2.8 +/- 0.3 vs 2.2 +/- 0.4; p = 0.0058) had significantly improved, whereas low attenuation area and central bronchiectasis had not. There were positive correlations of improved scores of centrilobular nodules with improved %VC (r = 0.58, p = 0.0062) and RV/TLC% (r = 0.64, p = 0.0022). Decreased air trapping in DPB correlates with an improvement of centrilobular nodules, which reflects the obstructive lesions of bronchioles during the erythromycin therapy.

Respiratory symptoms and pulmonary functional changes in patients with irritable bowel syndrome.

Scientific evidence of functional interface between the immune and sensory motor systems of the gut and respiratory systems has been reported. In recent studies excess prevalence of bronchial hyper-responsiveness has been shown among patients with irritable bowel syndrome (IBS). The purpose of our study was to investigate the possible relationship between IBS and asthma. One hundred thirty-three patients with IBS (108 women, 25 men) and 137 control subjects (105 women, 32 men) were included in this study. Both for IBS and the control group, the mean ages were 41.64+/-9.45 yr and 39.94+/-10.62 yr, respectively. Patients more than 50 yr old, with any organic GI disease, acute respiratory system infection, current or ex-smokers, and patients using drugs affecting smooth muscle and autonomic nervous system were not included in the study. Respiratory symptoms were questioned and pulmonary function tests were performed for every subject. There were 45 (33.8%) and eight (5.8%) subjects with respiratory symptoms in IBS and control groups, respectively (p < 0.0001). Twenty-one (15.8%) patients from the IBS group and two (1.45%) patients from the control group had the diagnosis of asthma according to history, clinical, and PFT findings. There was no statistical difference between two groups with respect to percentage of forced vital capacity and forced expiratory volume in 1 s-to-forced vital capacity. The difference between the two groups in forced expiratory volume in 1 s, flow after 50% of the vital capacity has been exhaled, peak expiratory flow rate, and maximal mid-expiratory flow rate was statistically significant (p < 0.01). We found that the prevalence of asthma was more common in the IBS group than in controls. Our finding supports the speculation that asthma and IBS may share common pathophysiological processes.

Respiratory symptoms and pulmonary functional changes in patients with irritable bowel syndrome

OBJECTIVE: Scientific evidence of functional interface between the immune and sensory motor systems of the gut and respiratory systems has been reported. In recent studies excess prevalence of bronchial hyper-responsiveness has been shown among patients with irritable bowel syndrome (IBS). The purpose of our study was to investigate the possible relationship between IBS and asthma. METHODS: One hundred thirty-three patients with IBS (108 women, 25 men) and 137 control subjects (105 women, 32 men) were included in this study. Both for IBS and the control group, the mean ages were 41.64 ± 9.45 yr and 39.94 ± 10.62 yr, respectively. Patients more than 50 yr old, with any organic GI disease, acute respiratory system infection, current or ex-smokers, and patients using drugs affecting smooth muscle and autonomic nervous system were not included in the study. Respiratory symptoms were questioned and pulmonary function tests were performed for every subject. RESULTS: There were 45 (33.8%) and eight (5.8%) subjects with respiratory symptoms in IBS and control groups, respectively ( p < 0.0001). Twenty-one (15.8%) patients from the IBS group and two (1.45%) patients from the control group had the diagnosis of asthma according to history, clinical, and PFT findings. There was no statistical difference between two groups with respect to percentage of forced vital capacity and forced expiratory volume in 1 s-to-forced vital capacity. The difference between the two groups in forced expiratory volume in 1 s, flow after 50% of the vital capacity has been exhaled, peak expiratory flow rate, and maximal mid-expiratory flow rate was statistically significant ( p < 0.01). CONCLUSION: We found that the prevalence of asthma was more common in the IBS group than in controls. Our finding supports the speculation that asthma and IBS may share common pathophysiological processes

Diving: what to tell the patient with asthma and why?

Until a decade ago, divers with asthma were uniformly barred from diving with compressed air. This prohibition was based more on theoretical concerns for barotrauma than on actual data. Follow-up studies, although retrospective, do not support a ban on recreational or commercial diving for divers with stable asthma. These studies have noted that, despite the prohibition on diving, many divers with asthma have logged multiple dives without negative consequences. When those who have suffered diving-related barotrauma have undergone physiologic testing, measurements of small airways dysfunction (maximal mid-expiratory flow rates) have been lower than measurements for comparable divers who have never suffered diving accidents. Follow-up studies with long-term commercial divers have shown that a small percentage of individuals who have sufferred diving-related barotrauma also develop abnormal maximal mid-expiratory flow rates and even some airway hyperreactivity. These latter findings correlate with the changes that occur in chronic asthmatic patients, especially those who are not well treated. The decision as to whether an asthmatic patient should be allowed to dive rests on the individual's physiologic function, maturity, and insight into the consequences of poorly managed airway inflammation and bronchospasm.