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Results for “Forced Expiratory Flow Rates”

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PubMed1981

Sensitivity of forced expiration indices to induced changes in peripheral airway resistance.

To assess the actual sensitivity of forced expiration indices to changes in the resistance of peripheral airways, maximal expiratory flow-volume curves were obtained in 30 normal subjects breathing air and breathing an O2-Ne-SF6 gas mixture having the same density as air but a 45% larger viscosity. The measurements were made using a bag-in-box system to circumvent calibration problems, and the data were processed digitally. Besides the usual forced expiration indices, slope ratios, as described by Mead (J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 44: 156-165, 1978), and transit time indices were also computed. Breathing the viscous mixture, the largest changes were seen with the slope ratio measured at 60% forced vital capacity, followed by other slope ratios, the standard deviation of transit times, and maximal flows at low lung volumes. However, when the data were compared using the t test for paired measurements, the most significant changes were found with the forced expiratory volumes at 1 and 2 s, due to their low within-subject variability. These indices may therefore by considered as the most suitable for detecting changes in individuals.

Adult↗

PubMed1985

Lack of effect of airway anesthesia on hypoxic ventilation.

Airway anesthesia causes an increase in ventilation (VE) during hypercapnia. However, it is unclear if that is related to an effect of the anesthesia on all forms of stimulated V.E or just hypercapnic VE. After airway anesthesia, an increase in hypoxic VE would suggest the former, whereas absence of an increase would suggest the latter. Thus we compared VE before and after airway anesthesia during hypoxic VE. Normal subjects performed hypoxic rebreathing plus additional periods of sham hyperoxic rebreathing. There was no effect of airway anesthesia on the slope of the line relating VE and arterial O2 saturation. However, there was an upward shift in the line, attributable to an effect of anesthesia on hypercapnic VE present during rebreathing. Additional normal subjects performed eucapnic hypoxic breathing, and there was no effect of airway anesthesia on VE. We conclude that airway anesthesia has little or no effect on hypoxic VE. To date, only hypercapnic VE has been shown to be increased after airway anesthesia.

Adult↗

PubMed1987

Cardiac output by rebreathing in patients with cardiopulmonary diseases.

Noninvasive estimates of cardiac output by rebreathing soluble gases (Qc) can be unreliable in patients with cardiopulmonary diseases because of uneven distribution of ventilation to lung gas volume and pulmonary blood flow. To evaluate this source of error, we compared rebreathing Qc with invasive measurements of cardiac output performed by indicator-dilution methods (COID) in 39 patients with cardiac or pulmonary diseases. In 16 patients with normal lung volumes and 1-s forced expiratory volumes (FEV1), Qc measured with acetylene [Qc(C2H2)] overestimated COID insignificantly by 2 +/- 9% (SD). In subjects with mild to moderate obstructive lung disease, Qc(C2H2) slightly overestimated COID by 6 +/- 15% (P = 0.11). In patients with restrictive disease or combined obstructive and restrictive disease, Qc(C2H2) underestimated COID significantly by 9 +/- 14% (P less than 0.04). The magnitude of the discrepancy between Qc and COID correlated with size of the volume rebreathed and an index of uneven ventilation calculated from helium mixing during rebreathing that determined a dead space to inspired volume ratio (VRD/VI). Rebreathing volumes less than 40% of the predicted FEV or VRD/VI of 0.4 or greater identified all subjects with a discrepancy between Qc(C2H2) and COID of 20% or greater.

Cardiac Output↗

PubMed1993

Expiratory airflow limitation and hyperinflation during methacholine-induced bronchoconstriction.

To investigate the role of airflow limitation on the increase of end-expiratory lung volume (EELV) during bronchoconstriction, nine stable asthmatic subjects and seven healthy subjects were challenged with inhaled methacholine (MCh). Changes in airway caliber were assessed by using forced expiratory volume in 1 s, partial forced expiratory flow at 50% of control forced vital capacity, and specific airway conductance. To detect airflow limitation, tidal flow-volume curves were superimposed on partial forced flow-volume curves at absolute lung volume. The electromyogram of the diaphragm was recorded by surface electrodes in four asthmatic and four healthy subjects, and the electrical diaphragmatic activity (DIA) during expiration was expressed as a percentage of the duration of expiratory time. In 10 subjects (9 asthmatic and 1 healthy) the partial forced expiratory flow recorded after some MCh dose impinged on tidal expiratory flow recorded before MCh. When this occurred it was associated with an increase in EELV by 0.54 +/- 0.07 (SE) liter (P < 0.001), which was larger than that occurring when lower MCh doses (0.11 +/- 0.04 liter, P < 0.05) were used, and with a moderate increase in DIA of 15 +/- 2.5% (P < 0.01). Six healthy subjects did not increase EELV after MCh despite a significant degree of bronchoconstriction; in these subjects tidal expiratory flow never impinged on forced expiratory flow, and DIA never increased. These results suggest that hyperinflation during MCh-induced bronchoconstriction is triggered by dynamic compression of the airways and is associated with moderate increase of DIA during expiration.

Adolescent↗

PubMed1999

Effect of negative expiratory pressure on respiratory system flow resistance in awake snorers and nonsnorers.

In spontaneously breathing subjects, intrathoracic expiratory flow limitation can be detected by applying a negative expiratory pressure (NEP) at the mouth during tidal expiration. To assess whether NEP might increase upper airway resistance per se, the interrupter resistance of the respiratory system (Rint,rs) was computed with and without NEP by using the flow interruption technique in 12 awake healthy subjects, 6 nonsnorers (NS), and 6 nonapneic snorers (S). Expiratory flow (V) and Rint,rs were measured under control conditions with V increased voluntarily and during random application of brief (0.2-s) NEP pulses from -1 to -7 cmH(2)O, in both the seated and supine position. In NS, Rint,rs with spontaneous increase in V and with NEP was similar [3.10 +/- 0.19 and 3.30 +/- 0.18 cmH(2)O x l(-1) x s at spontaneous V of 1.0 +/- 0.01 l/s and at V of 1.1 +/- 0.07 l/s with NEP (-5 cmH(2)O), respectively]. In S, a marked increase in Rint,rs was found at all levels of NEP (P < 0.05). Rint,rs was 3.50 +/- 0.44 and 8.97 +/- 3.16 cmH(2)O x l(-1) x s at spontaneous V of 0.81 +/- 0.02 l/s and at V of 0.80 +/- 0.17 l/s with NEP (-5 cmH(2)O), respectively (P < 0.05). With NEP, Rint,rs was markedly higher in S than in NS both seated (F = 8.77; P < 0.01) and supine (F = 9.43; P < 0.01). In S, V increased much less with NEP than in NS and was sometimes lower than without NEP, especially in the supine position. This study indicates that during wakefulness nonapneic S have more collapsible upper airways than do NS, as reflected by the marked increase in Rint,rs with NEP. The latter leads occasionally to an actual decrease in V such as to invalidate the NEP method for detection of intrathoracic expiratory flow limitation.

Adult↗

PubMed2000

Forced expiration: a test for airflow obstruction in horses.

The purpose of this study was to assess whether our method of inducing forced expiration detects small airway obstruction in horses. Parameters derived from forced expiratory flow-volume (FEFV) curves were compared with lung mechanics data obtained during spontaneous breathing in nine healthy horses, in three after histamine challenge, and in two with chronic obstructive pulmonary disease (COPD) pre- and posttherapy with prednisone. Parameters measured in the healthy horses included forced vital capacity (FVC = 41.6 +/- 5.8 liters; means +/- SD) and forced expiratory flow (FEF) at various percentages of FVC (range of 20.4-29.7 l/s). Histamine challenge induced a dose-dependent decrease in FVC and FEF at low lung volume. After therapy, lung function of the two COPD horses improved to a point where one horse had normal lung mechanics during tidal breathing; however, FEF at 95% of FVC (4.9 l/s) was still decreased. We concluded that FEFV curve analysis allowed the detection of induced or naturally occurring airway obstruction.

Animals↗

PubMed2001

Saline aerosol bolus dispersion. II. The effect of conductive airway alteration.

In a companion study (Verbanck S, Schuermans D, Vincken W, and Paiva M, J Appl Physiol 90: 1754-1762, 2001), we investigated whether saline aerosol bolus tests could also be used to detect proximal, as opposed to peripheral, airway alterations. We studied 10 never-smokers before and after histamine challenge, obtaining, for various volumetric lung depths (VLD), saline bolus-derived indexes computed by discarding aerosol concentrations below either 50% of the exhaled bolus maximum (half-width, H) or below cutoffs ranging from 5 to 25% (standard deviation, sigma(5%)-sigma(25%)) and skew (sk(5)-sk(25%)). Multiple-breath N(2) washout-derived indexes of conductive (S(cond)) and acinar (S(acin)) ventilation inhomogeneity were also determined. After histamine, S(cond) significantly increased (P = 0.008) whereas S(acin) remained unaffected, indicating purely conductive airway alteration. Consistent with this observation, sk(5%) (or sk(25%)) was increased to the same extent at all VLD, and sigma(5%) was increased preferentially at low VLD. By contrast, H and sigma(25%) displayed preferential increases at high VLD, a pattern similar to that induced by peripheral alterations. The present work shows that proximal airway alteration can be reliably identified by saline bolus tests only if these include measurements at low and high VLD and if bolus dispersion is quantified as a standard deviation with a low cutoff.

Aerosols↗

PubMed2006

Restrained whole body plethysmography for measure of strain-specific and allergen-induced airway responsiveness in conscious mice.

The mouse is the most extensively studied animal species in respiratory research, yet the technologies available to assess airway function in conscious mice are not universally accepted. We hypothesized that whole body plethysmography employing noninvasive restraint (RWBP) could be used to quantify specific airway resistance (sRaw-RWBP) and airway responsiveness in conscious mice. Methacholine responses were compared using sRaw-RWBP vs. airway resistance by the forced oscillation technique (Raw-FOT) in groups of C57, A/J, and BALB/c mice. sRaw-RWBP was also compared with sRaw derived from double chamber plethysmography (sRaw-DCP) in BALB/c. Finally, airway responsiveness following allergen challenge in BALB/c was measured using RWBP. sRaw-RWBP in C57, A/J, and BALB/c mice was 0.51 +/- 0.03, 0.68 +/- 0.03, and 0.63 +/- 0.05 cm/s, respectively. sRaw derived from Raw-FOT and functional residual capacity (Raw*functional residual capacity) was 0.095 cm/s, approximately one-fifth of sRaw-RWBP in C57 mice. The intra- and interanimal coefficients of variations were similar between sRaw-RWBP (6.8 and 20.1%) and Raw-FOT (3.4 and 20.1%, respectively). The order of airway responsiveness employing sRaw-RWBP was AJ > BALBc > C57 and for Raw-FOT was AJ > BALB/c = C57. There was no difference between the airway responsiveness assessed by RWBP vs. DCP; however, baseline sRaw-RWBP was significantly lower than sRaw-DCP. Allergen challenge caused a progressive decrease in the provocative concentration of methacholine that increased sRaw to 175% postsaline values based on sRaw-RWBP. In conclusion, the technique of RWBP was rapid, reproducible, and easy to perform. Airway responsiveness measured using RWBP, DCP, and FOT was equivalent. Allergen responses could be followed longitudinally, which may provide greater insight into the pathogenesis of chronic airway disease.

Administration, Inhalation↗

PubMed2004

Attenuation of induced bronchoconstriction in healthy subjects: effects of breathing depth.

The effects of breathing depth in attenuating induced bronchoconstriction were studied in 12 healthy subjects. On four separate, randomized occasions, the depth of a series of five breaths taken soon (approximately 1 min) after methacholine (MCh) inhalation was varied from spontaneous tidal volume to lung volumes terminating at approximately 80, approximately 90, and 100% of total lung capacity (TLC). Partial forced expiratory flow at 40% of control forced vital capacity (V(part)) and residual volume (RV) were measured at control and again at 2, 7, and 11 min after MCh. The decrease in V(part) and the increase in RV were significantly less when the depth of the five-breath series was progressively increased (P < 0.001), with a linear relationship. The attenuating effects of deep breaths of any amplitude were significantly greater on RV than V(part) (P < 0.01) and lasted as long as 11 min, despite a slight decrease with time when the end-inspiratory lung volume was 100% of TLC. In conclusion, in healthy subjects exposed to MCh, a series of breaths of different depth up to TLC caused a progressive and sustained attenuation of bronchoconstriction. The effects of the depth of the five-breath series were more evident on the RV than on V(part), likely due to the different mechanisms that regulate airway closure and expiratory flow limitation.

Adult↗

PubMedDate not supplied

Newly diagnosed chronic obstructive pulmonary disease. Clinical features and distribution of the novel stages of the Global Initiative for Obstructive Lung Disease.

BACKGROUND: The new guidelines of the Global Initiative for Obstructive Lung Disease (GOLD) propose a novel staging system for COPD. This study describes the frequency distribution of GOLD stages in newly diagnosed COPD patients in a large city pulmonary practice. METHODS: All patients newly admitted between 1995 and 1996 were analyzed retrospectively. Incident COPD cases were classified according to GOLD criteria. RESULTS: Among 1,434 patients, 210 were diagnosed with chronic obstructive pulmonary disease (COPD) (60% males, age 55 years, range 20-82 years). 67.5% of the patients were current smokers, 27% ex-smokers, and 5.5% nonsmokers. Based on GOLD criteria, 37% had stage 0, 5% stage I, 46% stage II, and 12% stage III COPD. Symptoms leading patients to seek medical advice were cough (84%), exertional dyspnea (70%), and sputum (45%), with a median symptom duration of 12 months (range 1-240 months). Compared with patients with GOLD stages 0-1, those with stages 2-3 were older (60 vs. 47 years, p < 0.001), heavier smokers (40 vs. 20 pack-years, p < 0.001), had a longer duration of symptoms (24 vs. 6 months, p < 0.001), and elevated IgE (stage 3 only, p < 0.04 vs. stages 0-2). Interestingly, stage 0 COPD patients did not have 'normal' spirometry, as indicated by significantly lower FEV(1) (% predicted) and FEF(25-75) (% predicted), compared with age-matched nonsmoking controls (93.1 +/- 1.8 vs. 99 +/- 1.6, p = 0.004; and 76.2 +/- 2.8 vs. 91.2 +/- 2.9, p = 0.0003, respectively). CONCLUSIONS: The majority of COPD patients seek medical advice at advanced disease stages, and smoke actively despite severe symptoms and functional impairment. However, nearly every second patient presents at stages 0-1, thus opening a window for therapeutic or behavioral intervention. GOLD guidelines are a useful basis to reinforce screening programs aimed at early detection and prevention of progressive COPD in individuals at risk and smoking cessation.

Adult↗

PubMedDate not supplied

Airflow limitation and breathing strategy in congestive heart failure patients during exercise.

BACKGROUND: Congestive heart failure (CHF) patients experience dyspnea on exertion and therefore have decreased exercise tolerance. OBJECTIVE: This study explores the hypothesis that stable New York Heart Association (NYHA) class III CHF patients without a history of pulmonary disease exhibit airflow limitation with increasing exercise. METHODS: We characterized flow limitations and breathing reserves at baseline, during exercise before anaerobic threshold (pre-AT), and after anaerobic threshold (post-AT) in CHF patients and normal subjects. Data were collected in the form of maximal flow volume loops and subsequent tidal flow volume loops at baseline and during exercise. Expiratory flow limitation was expressed as percent of tidal volume that corresponded with overlap of the tidal flow volume loops and maximal flow volume loops during expiration. The area directly between the maximum flow volume loops and the tidal flow volume loops during the expiratory phase is expressed as expiratory flow volume reserve (EFVR). RESULTS: CHF patients experienced expiratory flow limitation during exercise (pre-AT and post-AT) that was significantly increased compared to baseline and to normal subjects at similar exercise levels (CHF, baseline 8.5 +/- 7, pre-AT 37 +/- 10, post-AT 38 +/- 8%, n = 9, p < 0.05). Both CHF patients and normal subjects increased EFVR during exercise, but only the normal subjects increased EFVR to a significantly different value at post-AT exercise levels (normal subjects, 9.5 +/- 2, 11 +/- 2, 32 +/- 4%, n = 7, p < 0.05). Both CHF patients and normal subjects increased end inspiratory lung volume (EILV) during exercise, but only the normal subjects significantly increased EILV at post-AT exercise levels (normal subjects, 49 +/- 4, 55 +/- 5, 76 +/- 4%, p < 0.05). Inspiratory capacity (IC)/forced vital capacity (FVC) ratios were increased in CHF patients compared to normal subjects. However, IC/FVC values did not change during exercise in either group. CONCLUSIONS: CHF patients cannot utilize their full respiratory capacity during exercise secondary to expiratory flow limitation and an inability to increase EILV and EFVR.

Exercise↗

PubMed2005

Association between beta2-adrenergic receptor genetic polymorphisms and nocturnal asthmatic patients of Chinese Han nationality.

BACKGROUND: As a result of the finding that the mutation of Arg into Gly at beta(2)-adrenergic receptor (beta(2)-AR)16 loci could promote the downregulation effect triggered by the beta(2)-agonist, it was supposed that Gly16 might be associated with the downregulation of beta(2)-AR in patients with nocturnal asthma. OBJECTIVE: It was the aim of this study to analyze the association between beta(2)-AR genetic polymorphisms and nocturnal asthmatic patients of Chinese Han nationality. METHODS: A polymerase chain reaction allele-specific oligonucleotide hybridization assay was used to determine 16 and 27 loci alleles of beta(2)-AR genetic polymorphisms in 25 nocturnal asthmatic patients (nocturnal asthma group), 22 non-nocturnal asthmatic patients (non-nocturnal asthma group), and 72 healthy people (control group). All people investigated were of Chinese Han nationality. RESULTS: The distribution frequency of genotype Arg/Arg, Arg/Gly, and Gly/Gly at beta(2)-AR 16 loci was 12, 16 and 72% in the nocturnal asthma group; and 27, 41 and 32% in the non-nocturnal asthma group. There was a significant increase in the frequency of genotype Gly/Gly and allele Gly in the nocturnal asthma group compared with the non-nocturnal asthma group (p < 0.01). However, there was no significant difference in the frequency of genotype Gly/Gly and allele Gly in the non-nocturnal asthma group, compared with the control group. There was no significance in the frequency of the genotypes and alleles of beta(2)-AR 27 loci among the three groups (p > 0.05). CONCLUSION: The Gly16 polymorphism of beta(2)-AR was overrepresented in nocturnal asthmatic patients, correlated with nocturnal asthma, and therefore appeared to be an important genetic factor in the expression of this asthmatic phenotype.

Adult↗

PubMed1975

Evaluation of a new oral beta2-adrenoceptor stimulant bronchodilator, terbutaline.

A double-blind crossover comparison was made of the effect of orally administered terbutaline (a new adrenergic drug with major action on beta2-receptors), ephedrine, and placebo in 15 patients with obstructive airways disease. Serial determination of ventilatory tests, arterial gas tensions, arterial blood pressure, ECG, blood chemistries, and urinalysis were made before and after administration of the tested drug. Terbutaline (5 mg) was found to be an effective bronchodilator with minimal side effects and an earlier onset and longer duration of action than ephedrine (25 mg).

Administration, Oral↗

PubMed1984

Influence of an extension tube on the bronchodilator efficacy of terbutaline delivered from a metered dose inhaler.

Pressurized aerosols of sympathomimetic drugs are widely used in the treatment of bronchial asthma. The efficacy of this form of treatment is diminished in a number of patients by difficulties in coordination between the aerosol actuation and the inhalation. In order to improve the intrapulmonary deposition of terbutaline, an extension tube has been adapted to the regular pressurized aerosol device. In a cross-over randomized study we compared the bronchodilatory effect of increasing doses of terbutaline (250, 500 and 750 micrograms at 25-min intervals) either delivered by the regular pressurized aerosol device or by the device with the extension tube. The study was performed on 11 adult patients with reversible airways obstruction. Spirometry, body plethysmography and flow volume curves were performed. The onset of the bronchodilatory effect of a single dose of 250 micrograms terbutaline was more rapid after delivery via the extension tube. The addition of the extension tube caused a significantly higher bronchodilator efficacy of aerosolized terbutaline on the small airways. Our results show that the addition of an extension tube improves the bronchodilator efficacy of terbutaline delivered from a pressurized aerosol.

Adolescent↗

PubMed1986

Changes of volume of trapped gas after bronchodilation in subjects with suspected subclinical emphysema.

We studied the volume of trapped gas (VTG), using a nitrogen washout method, before and after bronchodilation in four groups with theoretically increasing risk of developing pulmonary emphysema: (1) nonsmoking healthy controls (PiMn), (2) nonsmoking subjects with an intermediate alpha 1-antitrypsin deficiency (PiMZn), (3) smoking subjects with normal concentration of alpha 1-antitrypsin, and (4) smoking PiMZ subjects. VTG was the only lung function variable that showed a significant difference between PiMZn and PiMn subjects but only after bronchodilation. Some conventional lung function tests also distinguished smokers from nonsmokers of both genotypes but VTG was the most sensitive test. VTG decreased after salbutamol inhalation in the control group but showed a consecutively larger increase with more risk factors of developing emphysema. An increase in VTG after bronchodilation may be a sign of alveolar abnormality preceding development of clinical lung emphysema.

Albuterol↗

PubMed1989

Responses of upper-airway dilating muscles and diaphragm activity to end-expiratory pressure loading in anesthetized dogs.

The steady-state responses of upper-airway dilating muscles and diaphragm activity to elevation of lung volume induced by positive end-expiratory pressure loading were studied in 9 pentobarbital-anesthetized dogs with vagus nerves intact. The early and late effects of 5 min of expiratory threshold loads upon upper airway dilating muscle activity (the alae nasi, the genioglossus and the posterior cricoarytenoid) were compared to their effects on diaphragm activity. During resting O2 breathing, application of 5 and 10 cm H2O of positive end-expiratory pressure produced no significant change in the peak electrical activity of the upper-airway dilating muscles and diaphragm (p greater than 0.05). No qualitative differences were found in the upper-airway dilating muscles and diaphragm responses to expiratory threshold loads when the animals breathed 3 or 7% CO2 in O2, compared to when they inspired 100% O2. Furthermore, no differences were found in the electrical activity of the upper-airway dilating muscles and diaphragm at any given end-tidal CO2 when unloaded responses were compared with loaded responses during progressive hypercapnia. However, positive end-expiratory pressure loading caused significant prolongation of expiratory duration, which gradually returned toward control levels when the loads were maintained. In animals who developed periodic breathing by increasing levels of anesthesia, positive end-expiratory pressure loading eliminated the periodicity and made the pattern of breathing regular. Based on these results, it can be concluded that under the conditions of these experiments, increases in lung volume produced by expiratory threshold loads do not reduce the activity of upper-airway dilating muscles. The maintenance of the electrical activity of the upper-airway dilating muscles might be caused by excitatory reflex mechanisms or central habituation.

Animals↗

PubMed1991

Influence of weight on pulmonary function in the adult guinea pig.

We examined a group of 63 adult female Hartley strain guinea pigs with weight ranging from 625 to 1,200 g in order to ascertain whether pulmonary function tests including lung volumes, pressure-volume curves, and flow-volume curves were affected by the weight of the animal. We found that there was a weight effect on total lung capacity, vital capacity, residual volume, and the forced expiratory flow between 25 and 75% of total lung capacity, although there was no effect on other parameters of airflow. Flow-volume curves for each animal could be accurately fitted to a mathematical equation, and this equation did not vary with the animals' weight. Pressure-volume curves were affected by animal weight, but could be accurately fitted to a weight-corrected equation. We conclude that when pulmonary function tests are performed on adult guinea pigs, lung volumes may be altered in proportion to the weight of the animal. When pressure-volume or flow-volume curves are being considered, although weight can either be corrected for or has no bearing on the shape of the curve, there is a large between-animal variation, and it may be necessary to use large experimental groups when it is impossible to use the same animal as its own control.

Animals↗

PubMed1994

Indices of upper airway obstruction in patients with simultaneous chronic airflow limitation.

In patients with chronic airflow limitation (CAL), the detection of upper airway obstruction (UAO) by analysis of forced flows can be difficult due to the masking of conventional UAO indices. We analyzed five indices: maximum inspiratory flow at 50% of forced vital capacity (FIF50), the ratio of maximum expiratory to inspiratory flow at 50% of forced vital capacity (FEF50/FIF50), the ratio FEV1/PEFR, the ratio FEV1 to forced expiratory volume in 0.5 s (FEV1/FEV0.5), and the ratio maximum voluntary ventilation (MVV)/FEV1, to determine their usefulness in evaluating patients with simultaneous UAO and CAL. One hundred and thirty-seven patients participated: 54 had UAO alone, 23 presented simultaneous UAO and CAL and 60 suffered from CAL with no evidence of UAO. The patients with UAO and CAL on the average presented fewer abnormal indices and these were less severely altered. Twenty-seven of the 60 with CAL alone presented at least one abnormal index, but in no case were more than two present. FEF50/FIF50 and FEV1/PEFR were significantly less sensitive in patients with both UAO and CAL than in those with UAO alone (35 vs. 85% and 52 vs. 72%, respectively). In all patients the most specific indices (100%) were FEF50/FIF50 and MVV/FEV1. The index MVV/FEV1 was the most accurate in patients with UAO and CAL. We conclude that when patients with CAL present 3 or more abnormal UAO indices, or have FEF50/FIF50 > or = 1 or MVV/FEV1 < or = 25, the possibility of simultaneous UAO must be strongly considered.

Adult↗