Peak expiratory flow ("peak flow") predicts important outcomes in older persons. Nevertheless, its clinical application is uncertain because prior strategies for reporting peak flow may not be valid. We thus determined the frequency distribution of peak flow by the conventional strategy of percent predicted (%predicted) and by an alternative method ...

To our knowledge, there is no data on the effect of tiotropium on pulmonary gas exchange in healthy subjects. The aim of this study was to assess the effects of tiotropium on pulmonary diffusing capacity. Twenty-one healthy volunteers were enrolled for a prospective, randomized, double-blind, placebo-controlled study. Spirometric measurements, including ...

There is increasing concern that airborne particles are critical risk factors for adverse health conditions in susceptible populations. The objective of this panel study is to investigate an association between particulate matter and the peak expiratory flow rate (PEFR) in the elderly and to compare estimated risks using PM10 or ...

Injection laryngoplasty restores voice in subjects with unilateral vocal fold paralysis, but knowledge of its effects on airflow dynamics is limited. Impulse oscillometry (IOS) is a non-invasive technique to investigate airway resistance. It is easily performed during normal breathing. A prospective study was conducted in order to investigate the effects ...

Air exhaled by cigarette smokers contains reduced amounts of nitric oxide (NO). Measurement of NO at different expiratory flow rates permits calculation of NO production by the conducting airways (Vaw(NO)) and alveolar concentration of NO (P(ALV)). An independent measurement of diffusing capacity of the alveolar compartment (D(LNO)) multiplied by P(ALV) ...

Flow limitation in the airways is a fundamental process constituting the maximal expiratory flow-volume curve. Its location is referred to as the choke point. In this work, expressions enabling the calculation of critical flows in the case of wave-speed, turbulent or viscous limitation were derived. Then a computational model for ...

BACKGROUND: Acquired tracheobronchomalacia (TBM) can cause central airway collapse in patients with COPD and may worsen airflow obstruction and symptoms. It is usually not known whether central airway malacia contributes to airflow obstruction. This study was undertaken to quantify central airway collapsibility and relate it to expiratory flow limitation in ...

BACKGROUND: The physicochemical properties of propofol could allow diffusion across the alveolocapillary membrane and a measurable degree of pulmonary propofol elimination. The authors tested this hypothesis and showed that propofol can be quantified in expiratory air and that propofol breath concentrations reflect blood concentrations. This could allow real-time monitoring of ...

OBJECTIVES/HYPOTHESIS: A model of airway obstruction was developed to study the impact of changes in airway resistance on ventilatory mechanics. This was used to derive quantitative indices of airway obstruction to aid in the objective diagnosis and physiological monitoring of adult patients with laryngotracheal stenosis (LTS). METHODS: Six airway resistors, ...

Few studies are available concerning correlations between pulse oximetry and peak expiratory flow in children and adolescents with acute asthma. Although the Global Initiative for Asthma states that measurements of lung function and oximetry are critical for the assessment of patients, it is not clear if both methods should necessarily ...

OBJECTIVE: The objective of this study was to determine whether long-term steroid therapy is associated with increased peak cough flow in patients with Duchenne muscular dystrophy and to determine which pulmonary function test variable is most predictive of peak cough flow. METHODS: In this case-control study, the medical charts of ...

AIM: To identify pollen types in southern Croatia and investigate the impact of sensitization to Ambrosia elatior (A. elatior) on symptoms and treatment of patients with seasonal allergic rhinitis and/or asthma. METHODS: The study recruited 120 patients from Split-Dalmatian County with seasonal rhinitis and asthma symptoms and positive skin prick ...

BACKGROUND: Inhaled asbestos fibres can cause inflammation and fibrosis in the lungs called asbestosis. However, there are no non-invasive means to assess and follow the severity of the inflammation. Exhaled nitric oxide (NO) measured at multiple exhalation flow rates can be used to assess the alveolar NO concentration and bronchial ...

Distribution patterns of odorant molecules in the rat nasal olfactory region depend in large part on the detailed airflow patterns in the nasal cavity, which in turn depend on the anatomical structure. To investigate these flow patterns, we constructed an anatomically accurate finite element model of the right nasal cavity ...

The influence of particle size upon deposition in the human airways is well understood. Pharmaceutical aerosol formulators strive to generate fine aerosols with the potential to penetrate into the deep lung. However, flow rate can also have a major influence on deposition, particularly with coarse aerosols. This study investigated the ...

Chronic obstructive pulmonary disease is attaining alarming proportions that requires more objective and quantitative ways for the diagnosis and the evaluation / stratification of, both, the disease and the therapeutic outcomes. Within this context, the present study explores the possibility to increase the effectiveness of spirometry through signal analysis. Expiratory ...

OBJECTIVE: To study the changes in pulmonary function of human male volunteers from 2 different populations: Indians and Kyrgyzis before and after ascent to 3,200 m and during a 4-week stay at that altitude. METHODS: Ten healthy soldiers of the Indian army (22-25 years of age) and 10 Kyrgyzis recruits ...

BACKGROUND: Horses with recurrent airway obstruction (heaves) are described as exhibiting "increased abdominal effort," but it is unknown whether this translates to an effective contribution to ventilation. HYPOTHESIS: We hypothesized that heaves is characterized by asynchrony between rib cage and abdominal motions, and that the abdominal component is the major ...

The urinary flow patterns and the Toguri nomogram were compared in the intermediate functional results of the tubularized-incised plate urethroplasty (TIPU) to repair distal and midpenile hypospadias by using uroflowmetry. 28 children who were toilet trained, were able to void volitionally, and had no fistulas following hypospadias repair were eligible ...

AIM: Exhaled ethane, pentane and isoprene have been proposed as biomarkers of oxidative stress. The objectives were to explore whether ethane, pentane and isoprene are produced within the airways and to explore the effect of different sampling parameters on analyte concentrations. METHODS: The flow dependency of the analyte concentrations, the ...

PURPOSE: The purpose of the study was to determine how air flow profiles affect fine particle fractions (FPF) (<5 microm) from dry powder aerosol formulations and whether laser diffraction (LD) could be used to measure FPF of aerosols generated by variable flows. MATERIALS AND METHODS: Carrier-based formulations containing 1.5% w/w ...

Human ventilation is aperiodic, exhibiting a breath-by-breath variability and a complexity of which the characteristics may be interesting physiologically and clinically. In the present study, we tested the ability of respiratory inductive plethysmography (RIP) to describe these properties. Indeed, RIP does not have the effects on ventilation described with mouthpiece ...

BACKGROUND: The contribution of the metal components of particulate pollutants to acute respiratory effects has not been adequately evaluated. Moreover, little is known about the effects of genetic polymorphisms of xenobiotic metabolism on pulmonary function. OBJECTIVES: This study was conducted to assess lung function decrement associated with metal components in ...

The transient airflow in a rigid, asymmetric monopodial sheep (ovine) tracheobronchial tree of up to 13 generations was investigated numerically. The lung geometry was segmented and reconstructed from computed-tomographic (CT) images. The flow characteristics in the image-based sheep airway were compared with the flow patterns produced by a Weibel-based model ...

The pattern of breathing was studied in 13 premature newborns treated by variable-flow Nasal Continuous Positive Airway Pressure (NCPAP), conventional NCPAP, and nasal cannulae. Compared to constant-flow NCPAP and nasal cannulae, the variable-flow NCPAP increases tidal volume and improves thoraco-abdominal synchrony, suggesting that variable-flow NCPAP provides more effective ventilatory support ...

Peak flow monitoring of asthma came into vogue with the advent of asthma self-management programs. Because it offered an objective way to gauge asthma severity, it promised improvement in the accuracy of asthma monitoring over that attainable by symptom monitoring. This promise has not been fulfilled. The ensuing years have ...

Volutrauma caused by artificial ventilation represents a major morbidity risk for premature infants. Our working group has recently developed an innovative "split-flow ventilation" system aiming at the reduction of tidal volumes (TVs). The main problem for the practical use of this system is the fact that conventional measurements of commercially ...

It has been proposed that a titration of the mandibular positioner would be a promising method for predicting the outcome of nasal continuous positive airway pressure (CPAP) therapy. This study was carried out to test the hypothesis that mandible advancement could be evaluated by analysis of inspiratory flow limitation using ...

We investigate flows on graphs whose links have random capacities. For binary trees we derive the probability distribution for the maximal flow from the root to a leaf, and show that for infinite trees it vanishes beyond a certain threshold that depends on the distribution of capacities. We then examine ...

OBJECTIVE: To assess whether Ramadan fasting affects the expiratory flow rates in healthy subjects, and to know if these effects correlate to a change in other variables. METHODS: This unmatched case-control longitudinal study includes 46 non-smoking healthy subjects who undertook lung function testing at the Aga Khan University, Pakistan. Expiratory ...

OBJECTIVES: The aim of this prospective study was to verify whether vocal fold fat augmentation (VFFA) modifies upper airway patency. To the best of our knowledge, this is the first study analyzing the impact of VFFA on laryngeal resistance to airflow. METHODS: Twenty-one consecutive patients 16 to 74 years of ...

The within-breath change in reactance (Delta(rs)) measured by forced oscillation technique (FOT) at 5 Hz reliably detects expiratory flow limitation in chronic obstructive pulmonary disease (COPD). The present study compared this approach to the standard negative expiratory pressure (NEP) method. In total, 21 COPD patients were studied by applying both ...

Although normal lungs may be represented satisfactorily by symmetrical architecture, pathological conditions generally require accounting for asymmetrical branching of the bronchial tree, since lung heterogeneity may be significant in respiratory diseases. In the present study, a recently proposed symmetrical dynamic morphometric model of the human lung, based on Weibel's regular ...

The authors (Eiser et al 2005 Physiol. Meas. 26 143-56) have undertaken a much needed investigation into the extent of the flow dependence of resistance, as measured by the interrupter technique (Rint). The clear explanations of the general principles should prove invaluable to the readers. However, I should like to ...

BACKGROUND: Acute rejection, a vascular-based disorder, has been identified as the major risk factor for obliterative bronchiolitis (OB), an airway-based pathology. This study investigated the hypothesis that changes to the microvascular blood supply of small airways were associated with the development of OB, thus providing a possible link between an ...

This study determines the impact of provider knowledge and attitude on implementation of guidelines: spirometry, peak flows, patient assessments, action plans, severity assessment, and anti-inflammatories. A self-administered survey conducted in academic family practice sites in Buffalo, NY assessed knowledge, self-reported use, and perceived usefulness. Knowledge was associated with regular use ...

BACKGROUND: Due to economic and ethical problems, virtual organs may appear more convenient than experiments on animals or limited investigations on patients. In particular, a virtual respiratory system (VRS) may be useful for tasks such as respirators and support methods testing, education, staff (medical and technical) training, (initial) testing of ...

Studies of the efficacy of heliox in patients with severe asthma have shown mixed results. Among the factors that are responsible for variable outcomes, the failure of heliox delivery systems to prevent room air entrainment (RAE) during beta-agonist delivery is probably the most critical. While keeping the rotameter flow rate ...

There has been a long-standing debate regarding the adequacy of airflow rates used in respirator certification testing and whether these test flow rates underestimate actual values. This study investigated breath by breath inspiratory peak flow rate, minute ventilation, and instantaneous flow rates of eight young, healthy volunteers walking on a ...

PURPOSE: To quantify the unknown relative sensitivities of semiquantitative measures from dynamic contrast-enhanced (DCE) MRI to variations in the volume fraction V(e) of the extravascular extracellular space (EES), and the duration of the contrast injection. MATERIALS AND METHODS: Tissue-uptake curves were simulated across various values of F, PS, V(e), and ...

The primary objective of this study is to investigate the maintenance difference in basic anthropometric characteristics and to outline the dynamics of respiratory function change in youngsters athletes exposed to passive smoking (PS) and athletes not exposed to passive smoking in their families (NPS). High and weight were determined as ...

OBJECTIVE: To determine whether peak flow monitoring has value above and beyond symptom monitoring when used as part of an asthma management plan. METHODS: From a large managed-care organization, 296 adults, aged 50-92 yr, were recruited and randomly assigned in equal numbers to either use of symptoms or peak flow ...

Dispersion characteristics of expiratory aerosols were investigated in an enclosure with two different idealized airflow patterns: the ceiling-return and the unidirectional downward. A multiphase numerical model, which was able to capture the polydispersity and evaporation features of the aerosols, was adopted. Experiments employing optical techniques were conducted in a chamber ...

OBJECTIVE: The purpose of this study was to use phase-contrast MRI to evaluate the influence of various breathing maneuvers on the hemodynamics of the pulmonary and systemic arterial circulation. SUBJECTS AND METHODS: Twenty-five volunteers were examined with phase-contrast MRI. Flow measurements were acquired in the aorta, pulmonary trunk, and left ...

BACKGROUND: Some cellular and soluble markers of inflammation in induced sputum have been used for studying airway inflammation in asthma. The aim of this study was to assess the usefulness of systemic inflammation marker serum amyloid A (SAA) in blood and induced sputum to monitor the airway inflammation in asthmatic ...

This study evaluated the respiratory effects of a single dive in children. Eighteen young divers and 18 controls participated in our study (age range: 9 - 13 years). Volumes and expiratory flow rates were measured 20 minutes before and 10 minutes after one air dive (3 meters, 25 minutes). Before ...

The study was done to assess the influence of smoking on respiratory symptoms and respiratory function in sawmill workers in Benin City. 150 sawmill workers who were all males and aged between 18 and 50 years, and had been in continuous employment in sawmill factories for a minimum of one ...

BACKGROUND: Endotoxin was proposed to increase the severity of asthma. Endotoxin levels greatly differ according to settings. In domestic environments, airborne concentrations may be dramatically low compared with levels reported in occupational settings. OBJECTIVE: Our first objective was therefore to assess the effect of inhalation of low-level lipopolysaccharide (LPS) on ...

In this study, we investigate the beat-to-beat respiratory fluctuations in pulse wave transit time (PTT) and its subcomponents, the cardiac pre-ejection period (PEP) and the vessel transit time (VTT) in ten healthy subjects. The three transit times were found to fluctuate in pace with respiration. When applying a simple breath ...

OBJECTIVE: We compared two methods of delivering high-flow gas therapy by nasal cannula, applied immediately after planned endotracheal extubations of NICU patients. STUDY DESIGN AND METHODS: Thirty NICU patients who were about to be extubated from mechanical ventilation were randomized into two groups; Group 1 received Vapotherm for the first ...