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Results for “Forced Expiratory Flow Rates”

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PubMed1987

Nifedipine in asthma. Dose-related effect on resting bronchial tone.

In order to study the dose-related effect of nifedipine on expiratory flow rates, 15 asthmatic patients were given sublingually 10 mg and 20 mg of the drug on two different days and the FVC and FEV1 were measured during 90 minutes. Then they received 2.5 mg albuterol (Salbutamol) by inhalation, and the two parameters were measured again after 30 minutes. It was found that the drug has a dose-related effect on expiratory flow rates. Indeed, 20 mg nifedipine produced a mild (less than 10 percent) but significant improvement in FVC (p less than 0.01) and FEV1 (p less than 0.05), while the response to 10 mg was mild, not significant and manifested rather by a decrease in both parameters. In three patients, the forced expiratory flow rates markedly worsened. No correlation could be established between the effect of nifedipine and the severity of the disease. In contrast, the improvement produced by albuterol was strongly related to the degree of airway obstruction (p less than 0.001). Nifedipine in both doses did not potentiate the bronchodilatation induced by albuterol.

Adolescent↗

PubMed1981

Influence of breath holding at total lung capacity on maximal expiratory flow measurements.

1. Forced exhalations performed from volumes below total lung capacity, so-called partial expiratory flow-volume curves, are suggested to be more sensitive in detecting airways bronchoconstriction than maximal expiratory flow-volume curves begun at total lung capacity. 2. In eight healthy men both maximal and partial expiratory flow-volume curves were measured where breath was held at total lung capacity of 70% of vital capacity respectively, for either 0 or 15 s before performing the forced exhalation. An histamine aerosol was used to provoke bronchoconstriction. 3. The results showed that the 15 s breath hold caused greater reduction in expiratory flow rates after histamine for both maximal and partial expiratory flow-volume curves than either manoeuvres performed with no breath hold. 4. A breath hold of 15 s at total lung capacity appeared to make the maximal expiratory flow-volume curve as sensitive as a partial expiratory flow-volume curve in detecting the response to histamine as well as providing measurements of forced expiratory volume in 1 s and vital capacity. Forced spirometry after a 15 s breath hold at total lung capacity therefore provides an easy and sensitive technique for detecting bronchoconstriction.

Airway Obstruction↗

PubMed1996

Pulmonary function changes during epidural anesthesia for cesarean delivery.

Although changes in pulmonary function in parturients are documented, little is known about effects of regional anesthesia on these changes. This study was undertaken to determine if two local anesthetics, often used for epidural anesthesia for cesarean delivery, have different effects on pulmonary function testing. Nineteen ASA physical status I parturients undergoing elective cesarean delivery with epidural anesthesia were randomly assigned in double-blind fashion to receive either 0.5% bupivacaine or 2% lidocaine with epinephrine (1/200,000). Pulmonary function tests were measured using a calibrated spirometer with computer-recorded flow volume loops. Peak inspiratory pressure and peak inspiratory flow rate, peak expiratory pressure (PEP) and peak expiratory flow rate, forced vital capacity (FVC), and forced expiratory volume in 1 s (FEV1) were measured. Measurements were taken prior to epidural placement and at T-10 and T-4 levels. Peak inspiratory pressure, FEV1/FVC, FEV1, FVC, peak expiratory flow rate, and peak inspiratory flow rate did not differ from baseline in either group. Patients receiving lidocaine showed a significantly greater decrease in PEP at both T-10 and T-4 levels. Pep is largely dependent on abdominal musculature. If a denser motor block is provided by 2% lidocaine with epinephrine than by 0.5% bupivacaine, these muscles would be more affected, resulting in a greater decrease in PEP. These results may have implications regarding choice of local anesthetic for epidural anesthesia in parturients with some degree of respiratory compromise undergoing cesarean delivery.

Adult↗

PubMedDate not supplied

Emotionally induced decreases in pulmonary flow rates in asthmatic children.

This study found that vividly remembered incidents of intense anger and similarly recalled fear decreased 1-sec forced expiratory flow rates (FEV1)in 35 male and 25 female chronic asthmatic children who had no psychopathology. FEV1 increased with relaxation. Changes in FEV1 following anger correlated with changes following fear as highly as the reliabilities of the responses permitted, although anger produced a greater decrease than fear. FEV1 decrease following anger and fear correlated with FEV1 increase due to relaxation. The amount of change in each of the three conditions correlated with history of emotionally precipitated asthma. This pattern was interpreted to mean that the same phenomenon underlies emotional-bronchoconstriction, relaxation-bronchodilitation, and emotionally triggered asthma. No relationship was found between degree of allergic sensitivity (atopy) and FEV1 changes in any of the three conditions nor did atopy correlate with history of emotionally triggered asthma. These results do not support the view that psychological and allergic factors are inversely related, alternative causes of asthma.

Adolescent↗

PubMed1995

Loratadine in the treatment of cough associated with allergic rhinoconjunctivitis.

BACKGROUND: Antihistaminic treatment of allergic asthma or cough-type asthma, including cough associated with allergic rhinocojunctivitis, has been recently reconsidered prospectively since new very potent compounds, nonsedating with anti-allergic properties, are available. OBJECTIVE: The possible effectiveness of loratadine in the treatment of allergic cough was assessed in 20 patients with allergic rhinoconjunctivitis and cough due to Parietaria judaica during the pollen season (April to July 1993). METHODS: Allergic patients were enrolled in a double-blind, placebo-controlled, parallel-group, randomized study, and received loratadine 10 mg/d or placebo in oral tablets for 4 weeks. Occurrence and severity of conjunctival and nasal symptoms, severity and frequency of cough attacks were assessed daily by the patients together with peak expiratory flow evaluation performed twice a day, ie, in the morning and in the evening. Physicians evaluated conjunctival and nasal signs, and spirometry on admission (before treatment), 2 and 4 weeks after treatment. On admission methacholine challenge was also performed to assess PD20. Pollen counts were assessed during the study. RESULTS: According to patients' diary cards, ocular and nasal symptoms were progressively reduced by loratadine treatment (respectively P < .05 and P < .01), as well as cough frequency (P < .05) and cough intensity (P < .01). Peak expiratory flow rate, forced vital capacity, and forced expiratory volume in one second significantly decreased in the placebo-treated group (P < .01), while they were not modified in loratadine-treated patients, who remained normal. CONCLUSIONS: The study suggests that loratadine may be beneficial in the treatment of allergic cough, as well as in rhinoconjunctivitis. Further studies of this may be warranted.

Adult↗

PubMed1982

Effects of smoking and occupational exposure on peripheral airway function in young cereal grain workers.

We studied two groups of young male cereal grain elevator workers: 82 lifetime nonsmoking grain workers (2.5 +/- 1.2 yr of dust exposure) who were 22.7 +/- 3.5 yr of age, and 82 smoking grain workers (6.1 +/- 4.1 pack-years of smoking) individually matched to the nonsmoking grain workers for age (22.7 +/- 3.3 yr) and years of work in the grain industry (2.6 +/- 1.3 yr). We also studied the following groups of community control subjects: 82 nonsmoking community control subjects individually matched to the nonsmoking grain workers for age (22.8 +/- 3.7 yr), and 82 smoking community control subjects individually matched to the smoking grain workers for age (22.7 +/0 3.6 yr) and smoking history (6.0 +/- 4.0 pack-years). We measured forced expiratory volume in one second (FEV1), forced vital capacity (FVC), FEV1/FVC %, the maximal mid-expiratory flow rate (FEF25-75), the flow at 50% (Vmax50) and 25% (Vmax25) of a maximal expiratory flow-volume maneuver, the percent increase in the maximal expiratory flow at 50% FVC breathing a mixture of 80% helium-20% oxygen as compared with air (delta Vmax50), and the slope of Phase III of the single breath nitrogen test (delta N2/L). We also assessed the prevalence of respiratory symptoms from responses to a standardized questionnaire. Smoking was associated with an increased prevalence of cough, wheezing, and dyspnea, and a mildly decreased FEV1/FVC %. Two variables were used as indexes of small airway dysfunction, a lower delta Vmax50 and a higher delta N2/L. Only the group of workers who both smoked and were occupationally exposed to grain dust had evidence of small airway dysfunction. The differences in delta N2/L and delta Vmax50 were greater than was expected from an additive model, suggesting that the combined effects of occupational exposure to grain dust and inhalation of cigarette smoke may have a synergistic effect leading to small airway dysfunction in young cereal grain workers.

Adult↗

PubMed1987

The bronchoconstrictor properties of platelet-activating factor in humans.

Platelet-activating factor (PAF) is an inflammatory mediator that causes bronchial smooth muscle contraction in vitro and in vivo in experimental animals. To characterize the effect of PAF on human airways, 6 normal subjects and 6 subjects with mild asthma inhaled PAF using a standard bronchoprovocation protocol and nebulizer concentrations ranging from 0.1 to 1000 micrograms/ml. Aerosolized PAF produced bronchoconstriction in 5 of 6 normal and 3 of 6 asthmatic subjects as defined by at least a 35% decrease in specific airway conductance (SGaw). However, in these same subjects, flow rates measured at 30% of vital capacity from a partial forced expiratory maneuver (V30P) did not decrease at least 30% nor did the FEV1 decrease by 20%. The 8 PAF responders were 5 to 836 times more sensitive to PAF than to methacholine when SGaw was used to assess the airway response. The relative airway sensitivity of the PAF nonresponders could not be assessed. Normal and asthmatic subjects could not be differentiated by their airway response to PAF, and there were no clinical features that differentiated PAF responders from nonresponders. The maximal airway response to PAF occurred within 2 to 3 min and lasted 15 to 45 min. There were no late reactions. Both normal (p less than 0.01) and asthmatic (p less than 0.05) subjects exhibited tachyphylaxis to PAF. Finally, PAF sensitized the airways of all normal subjects to methacholine, including the one PAF nonresponder (p less than 0.02), but it did not sensitize the airways of the asthmatic subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMedDate not supplied

Air trapping in primary Sjögren syndrome: correlation of expiratory CT with pulmonary function tests.

PURPOSE: The purpose of our study was to correlate the extent of air trapping on expiratory CT scans with results of pulmonary function tests (PFTs) in a large group of patients with primary Sjögren syndrome and to determine whether these techniques may be complementary in assessing small airways obstruction. METHOD: Thirty-four nonsmoking patients with proven primary Sjögren syndrome and 10 healthy nonsmokers underwent paired inspiratory-expiratory thin section CT and PFTs. Expiratory scans were scored for the presence and extent of areas of air trapping. Extent of air trapping was assessed visually and given a score. The functional significance of the extent of air trapping was evaluated in both groups and then correlated with the results of PFTs. RESULTS: Bronchiolar abnormalities were seen in 11 (32%) of 34 patients with primary Sjögren syndrome. On the expiratory CT scans, a mosaic pattern of lung attenuation was identified in 17 patients. Air trapping was found in 44 of 204 lobar observations on the expiratory scans. The median point scale score at end-expiration was 3.6 (20%, Grade 1), ranging from 1 (5.5%, Grade 1) to 9 (50%, Grade 2). The mean total score of air trapping was more prevalent in lower (46/68) lobes (22.4%) than in upper (22/136) lobes (5.3%) (p < 0.001). PFTs were normal in the primary Sjögren syndrome patients as well as the healthy subjects. Air trapping was found more frequently in patients with primary Sjögren syndrome than in the healthy group. Only during exhalation was there evidence of minimal lobular-sized areas or air trapping (Grade 1) in three of the healthy subjects. We did not find any correlation between air trapping and PFTs including the forced expiratory flow rate between 25 and 75% of the forced vital capacity (FEF25-75). CONCLUSION: Expiratory high resolution CT revealed the extent of bronchiolar disease in patients with primary Sjögren syndrome. We also found that the extent of air trapping did not correlate with PFTs, which suggests the existence of a subclinical bronchiolar inflammatory process that may precede detectable abnormalities in lung function tests.

Adult↗

PubMed2000

Interrupter technique versus plethysmography for measurement of respiratory resistance in children with asthma or cystic fibrosis.

The purpose of the present study was to compare measurements of respiratory system resistance by the interrupter method (Rrsint) with those of airway resistance by plethysmography (Raw) in nonobstructed children with asthma or cystic fibrosis (ratio of forced expiratory volume in 1 sec to vital capacity, FEV(1)/VC >/=80% with a forced expiratory flow rate between 25-75% of forced vital capacity, FEF(25-75) >/=75% of normal values) and in obstructed children with the same diseases (FEV(1)/VC <80% and/or FEF(25-75) <75% of normal values). Eighty-one children (47 asthmatics and 34 suffering from cystic fibrosis) aged 5-18 years (mean 11.2 +/- SD 3.4 years) were included in the study. For the overall group, we observed generally lower values for Raw (4.7 +/- 2. 8 cmH(2)O.L(-).s) than for Rrsint20 (extrapolation of the mouth pressure during occlusion to 40 ms after interruption) (5.6 +/- 1.7 cmH(2)O.L(-1).s) (P < 0.02), or for Rrsint40 (extrapolation of the mouth pressure during occlusion to 60 ms after interruption) (6.6 +/- 2.2 cmH(2)O.L(-1).s) (P < 0.001), but there was no difference between Rrsint20 and Raw in the obstructed subgroup. Moreover, we observed a correlation between the difference (Rrsint20 - Raw) expressed in percentage of predicted values and the degree of obstruction estimated by FEV(1)/VC (r = 0.56, P < 0.001). The differences between the specific resistances (sRrsint20 - sRaw, sRrsint40 - sRaw) were also correlated with the severity of the obstruction (r = 0.65, P < 0.001 and r = 0.57, P < 0.001, respectively). We observed also that the tendency to underestimate resistance by Rrsint in obstructed children was not the same in children with asthma and cystic fibrosis. We conclude that the tendency of Rrsint, as measured with our method, to underestimate airway obstruction appears to increase in proportion to the severity of the airway obstruction.

Adolescent↗

PubMed1989

Relationship of byssinosis to the generation of oxygen radicals by bract tissues of cotton plants.

Byssinosis is a hazardous respiratory disorder of workers in natural fiber processing industries and, in the case of cotton, is caused by exposure to respirable dust generated from leafy trash associated with raw fibers. To understand the chemical characteristics of involucral trash components that might contribute to bysinosis, we examined the human airway constricting activity and oxygen radical generating activity of dry, frost-killed cotton bracts. In response to inhalation of aerosolized bract extracts, the expiratory flow rates of human volunteers at 40% of vital capacity during partial forced expiration decreased by 3 to 32%. These values enabled us to identify two potentially byssinogenically active bract specimens, a specimen virtually inactive, and a fourth intermediately so. Using spin trapping techniques of electron spin resonance spectrometry, we found that all specimens catalyzed the generation of hydroxyl (preponderantly) and superoxide radicals from hydrogen peroxide. However, the weakest constrictor was the most potent catalyst, and vice versa. This was consistent with transition metal content of the specimens; the most potent catalyst also contained the largest amounts of those metals, suggesting a Fenton-type reaction mechanisms. Other possibilities for the inverse relationship of airway constricting (byssinogenic) activity with oxygen radical generation are discussed. We also found that neither aflatoxin nor endotoxin, contingent contaminants of bracts, catalyzed oxygen radical production from hydrogen peroxide.

Aflatoxin B1↗

PubMed2000

[Clinical and experimental study on effect of Chanbei Kechuanping in treating bronchial asthma].

OBJECTIVE: To observe the clinical effect of Chanbei Kechuanping (CBKCP) on bronchial asthma and to explore its mechanism. METHODS: Ninety-six patients of bronchial asthma were randomly divided into two groups, the CBKCP treated group and the control group (treated by Guilong Kechuanning). The changes on symptoms and signs of asthma, pulmonary function, T-lymphocyte subsets, plasma soluble interleukin-2 receptor (sIL-2R), thromboxane B2(TXB2) and 6-keto-prostaglandin F1 alpha(6-keto-PGF1 alpha) were observed before and after treatment. RESULTS: (1) The markedly effective rate and effective rate in the CBKCP treated group were higher than those in the control group. The pulmonary function, including 1 second forced expiratory volume, maximum expiratory flow rate and forced lung expiratory vital capacity were all improved in both groups, but the effect was more obvious in the CBKCP treated group. (2) As compared with the control group, CBKCP showed more obvious effect in lowering sIL-2R, T-lymphocyte subset and raising 6-keto-PGF1 alpha. Experimental study of guinea pig with asthma model showed that CBKCP could markedly prolong the latent time of asthma attack, lower the percentage of mast cells in total cells in the alveoli lavage solution, blood acidophic cell count and degranulation rate of mast cells, and decrease IgE, IL-4 and TXB2 levels as well as increase the 6-keto-PGF1 alpha level. CONCLUSION: CBKCP has favorable therapeutic effect on asthma attack, it might play the role partly by regulating the functional T-lymphocyte subsets, reducing the level of IgE, sIL-2R, IL-4 and TXB2, and increasing the level of 6-keto-PGF1 alpha.

Adolescent↗

PubMed1995

Airway obstruction during exercise in asthma.

Airway obstruction (AO) in exercise-induced asthma (EIA) is considered a postexercise phenomenon. However, many with EIA complain of respiratory distress during exercise. We evaluated AO in six asthmatic subjects during a short (SX = 6 min) and a long (LX = 20 min) exercise session. We measured peak expiratory flow (PEF) rate, forced expiratory volume in one second (FEV1), and forced expiratory flow at 50% of vital capacity (Vmax50) and calculated expiratory and inspiratory pulmonary resistance (RLe and RLi). Rated perceived exertion (RPE) was evaluated as a measure of dyspnea. All three indices of airflow significantly decreased following SX and LX, but RLi and RLe increased. During SX, PEF, FEV1, and Vmax50 did not decrease, but RLi decreased. During LX, PEF, FEV1, and Vmax50 decreased (20.0, 26.0, and 17.7%, respectively), whereas RLi and RLe significantly increased (74.0 and 53.0%). Rated perceived exertion correlated highly with RLi during exercise (r = 0.95). In summary, there was little or no AO during SX but a frank AO during LX in asthmatic subjects. We conclude that AO occurs during LX and that the manifestation of dyspnea is associated with AO during exercise, as well as in recovery.

Adult↗

PubMed1993

The decrease in severity of asthma in children of parents who smoke since the parents have been exposing them to less cigarette smoke.

BACKGROUND: In 1985 we became aware that the smoking of parents aggravates their children's asthma. Since then we have advised all referring doctors to urge parents not to expose their asthmatic children to smoke. METHODS: We investigated 807 nonsmoking asthmatic children, from 1 through 17 years of age, who were consecutively referred between 1983 and 1990. We compared the children who were seen before July 1986 with those seen after that date. RESULTS: Those seen in the later period had intimate exposure to a far smaller number of cigarettes smoked per day, both by mothers (7 vs 3, p = 0.005) and by fathers (5 2, p = 0.001). A concurrent improvement was observed in adjusted measures of asthma severity in their children (asthma score 7.5 vs 6.5, p = 0.047; forced expiratory volume in 1 second as a percent of predicted [FEV1%] 79.2 vs 93.7, p = 0.000; and forced expiratory flow rate during middle half of forced vital capacity [FEF25%-75%] 67.3 vs 82.0, p = 0.009), and for every cigarette less smoked in the room with the child the FEV1 increased by 3%. When parents of those seen in the later period were asked whether they had been told that smoke would aggravate their child's asthma, 80% affirmed that they had. The difference in asthma severity between the two time periods was much less in children of nonsmokers than in children of smokers. CONCLUSION: It appears that if parents are aware that smoke will aggravate their child's asthma, the child will be exposed to fewer cigarettes, and the asthma will be less severe.

Adolescent↗

PubMed2002

A comparative study of effects of cigarette and bidi smoking on respiratory function tests.

The effects of cigarette and bidi smoking on pulmonary function tests have been studied in 90 healthy males from North India Forced vital capacity (FVC), peak expiratory flow rate (PEFR), forced expiratory volume in 1 sec (FEV) were determined in 30 nonsmokers (as control group), 30 cigarette smokers and 30 bidi smokers. All the above pulmonary function parameters were found to be lower among smokers as compared to nonsmokers. Moreover, the decrease in the pulmonary function tests was greater in cigarette smokers as compared to bidi smokers.

Adult↗

PubMed1973

Interrelation between alterations in pulmonary mechanics and hemodynamics in acute myocardial infarction.

Pulmonary mechanics were evaluated in 30 patients with acute myocardial infarction by measuring forced expiratory flow rates and total pulmonary resistance (R(T)) with the oscillometric method at the resonant frequency of the chest (6-8) cycle/s). During the first 3 days after infarction, forced expiratory volume (FEV) and forced mid-expiratory flow rate (FEF(25-75%)) were 69% and 60% of predicted values, respectively. 10 or more wk later these values were 95% and 91%. Initially, R(T) was 52% greater than predicted, but was only 4% greater 10 or more wk later. In 11 patients R(T) was measured at both resonant frequency and at 3 cycle/s. Five of these patients had no clinical signs of heart failure, but nine had abnormally high values of pulmonary artery pressure, "wedge" pressure and pulmonary extravascular water volume. All of these patients recovered. Initially, R(T) at resonance was 50% and R(T) at 3 cycle/s was 130% greater than predicted values. 2-3 wk later these figures were -3% and +6% of those predicted, respectively. At 10 wk or more, significant frequency dependence of R(T) had disappeared (R(T) at 3 cycle/s was 7% greater than R(T) at resonance). Isoproterenol inhalation in six patients caused no change in flow rates, R(T) at resonance, or R(T) at 3 cycle/s. R(T) at resonance and at 3 cycle/s, FEV, and FEF(25-75%) correlated significantly with the pulmonary vascular pressures. Patients with more marked arterial hypoxia and larger values for extravascular water volume had greater elevations of R(T) and depression of FEF(25-75%), but linear correlations were not significant. Clinical signs of congestive heart failure significantly correlated with a fall in FEV and FEF(25-75%), the development of frequency dependence of R(T), and elevation of the pulmonary wedge pressure. The initial elevation of R(T) and low flow rates indicate a modest degree of airway obstruction in acute myocardial infarction. Lack of response to isoproterenol suggests that bronchial muscular constriction is not a major factor. Frequency dependence of R(T) accompanied by elevated pulmonary vascular pressures and extravascular water volume indicates that pulmonary congestion causes the development of uneven time constants in the airways. Vascular engorgement and interstitial edema from elevated vascular pressures causing narrowing of the peripheral airways and closure of collateral airways could account for the above findings.

Acute Disease↗

PubMed2003

Pulmonary functional abnormalities in asymptomatic patients with systemic sclerosis.

BACKGROUND: Systemic sclerosis (SSc) is a disease characterized by widespread fibrosis of the skin and multiple organs, including the lungs. This study was designed to evaluate pulmonary function in SSc patients without symptoms of lung involvement. METHODS: Spirometric measurements were done in 26 female SSC patients without symptoms of pulmonary involvement. RESULTS: Maximal voluntary ventilation was found to be decreased in half of the patients, and forced vital capacity was decreased in 23% of the patients. Forced expiratory flow rate was impaired in about half of the SSc patients, especially the flow at 50-75% of forced vital capacity. Peak expiratory flow rate was decreased in 77% of asymptomatic patients. CONCLUSIONS: A functional defect, mainly of the restrictive type, was observed in the majority of asymptomatic patients with SSc. Pulmonary function testing is recommended for all SSc patients.

Journal Article↗

PubMed1995

Lung function measurement in general practice: a comparison of the Escort spirometer with the Micromed turbine spirometer and the mini-Wright peak flow meter.

It is important that new types of spirometer for widespread clinical use are pragmatically evaluated in primary care. This study compared measurements taken by a new portable Fleisch pneumotachograph spirometer (known as the Escort) with those of the commonly used mini-Wright peak flow meter and the Micromed Pocket turbine spirometer. A pragmatic study was conducted in two phases during routine surgeries at Aldermoor Health Centre, Southampton. Phase I compared the new spirometer with the mini-Wright peak flow meter and Phase 2 compared the new spirometer and the turbine spirometer. One hundred patients aged 5-88 years (56 patients with a history of chronic respiratory complaints and 44 patients without) entered Phase 1, and 100 patients aged 6-82 years (62 patients with a history of chronic respiratory complaints and 38 patients without) entered Phase 2. Each patient contributed only once to each phase, but some entered both phases on separate occasions. Ninety-five percent limits of agreement (mean +/- SD) were wide for all comparisons. Graphical plots revealed trends towards higher Escort values as mean values rose compared with both mini-Wright and turbine readings for peak expiratory flow rate and forced expiratory volume in one second. Possible over-reading of peak expiratory flow rate with the mini-Wright meter at low mean values was also seen. Readings taken with these different types of meter cannot be interchanged with confidence in clinical practice. The clinical significance of the theoretically more accurate measures of lung function produced with the new meter, and indeed of spirometry itself, needs further investigation.

Adolescent↗

PubMed1979

Human response to controlled levels of inert dust.

We studied nasal mucous flow, airway resistance, and subjective response in 16 young healthy subjects during 5-hour exposures to 2, 10, and 25 mg of inert dust per m3 in an environmental chamber. The dust was a fully polymerized plastic dust containing carbon black. The number of these particles in room air, expressed as a per cent of the total number of particles was 36, 41, 14, 7, and 2, respectively, for the aerodynamic size ranges less than or equal to 1.8, 1.9 to 5.3, 5.4 to 8.9, 9.0 to 12.4, and greater than or equal to 12.5 micron. No significant changes in nasal mucociliary clearance rate or nasal resistance were observed. At all dust concentrations there was a decrease in 1-sec forced expiratory volume, but not in the forced vital capacity or the forced expiratory flow during the middle half of the forced vital capacity. The nasal penetration fraction of particles was approximately 55 per cent for the smallest particles and 20 per cent for the largest particles. Discomfort was proportional to the concentration of dust, but lagged almost 2 hours behind the changes in dust concentration. The discomfort was never excessive; the main complaints were dryness in the nose and pharynx.

Adult↗