Lung elastance and resistance increase in the supine posture. To evaluate the effects of change in posture on regional lung mechanics at different lung volumes, lung elastance and resistance were measured at graded volume subdivisions and three esophageal levels at seated and supine body positions, using the esophageal balloon technique. ...

Respiratory system, lung, and chest wall resistances and dynamic elastances were determined in six anesthetized, paralyzed, and mechanically ventilated guinea pigs both before and after lower transversal abdominal opening performed at the level of the spina iliaca anterosuperior. Furthermore, the resistances were also split into their two components, one reflecting ...

The aim of this study was to describe the technique of manual hyperinflation as applied by physiotherapists. Ten physiotherapists volunteered to manually hyperinflate a test lung. The protocol randomly altered resuscitation circuits (Laerdal and Macgill) and respiratory compliance conditions. Measurements of tidal volume, airway pressure, inspiratory flow rate and inflation ...

Static lung volumes, lung elasticity, and airway patency indices were measured in 47 children operated on for ventricular septal defect (VSD). Open-heart surgery was performed at the age of 0.6-12.0 years (median 4.1 years). In the first group (34 subjects), after primary repair of the VSD, there was an increase ...

The aim of our study was to test whether the supine position or the sitting position worsens static, forced expiratory flows and measurements of lung mechanics in a group of aged subjects living in a nursing home who were clinically stable and without clinical evidence of cardiorespiratory diseases. Seventeen subjects ...

METHOD: The daily changes in respiratory function were monitored in 16 healthy male road inductees at sea level (SL) and at high altitudes (HA) of 3110 m, 3445 m, and 4177 m. Identical studies were also carried out on acclimatized low landers (ALL) staying at 3110 m and at 4177 ...

OBJECTIVE: The mechanical properties of the respiratory system (i.e., elastance and resistance) depend on the frequency, tidal volume, and shape of the flow waveform used for forcing. We developed a system to facilitate accurate measurements of elastance and resistance in laboratory and clinical settings at the frequencies and tidal volumes ...

The application of negative pressure to the airway opening [called the forced-deflation (FD) technique] allows the examination of maximal expiratory flow-volume curves in intubated infants who are unable to generate a voluntary maximal expiratory maneuver. We explored the questions of effort and volume dependence of flows generated by FD in ...

Little is known of the respiratory function in patients with growth hormone (GH) deficiency. The aim of the present study was to evaluate lung volumes and respiratory muscle strength in patients diagnosed as GH deficient in childhood. Ten patients diagnosed as GH deficient in childhood and ten healthy subjects entered ...

The value of interrupter resistance measurements has been questioned because these depend on equilibration between alveolar (PA) and mouth pressure (PAO), which may not occur during airway obstruction or in measurements in children. In order to determine whether airway geometry and its interaction with the lung volume can be obtained ...

The recruitment and derecruitment of lung units is one explanation of the hysteresis observed in an excised lung during inflation and deflation. A simplified model has been proposed in which the recruitment-derecruitment process is a function of end-expiratory pressure (Frazer, D.G., K.C. Weber and G.N. Franz, Respir. Physiol. 61: 277-288, ...

A fixed orifice or a fixed upper airway obstruction (UAO) causes an expiratory and inspiratory plateau-shaped limitation on maximal flow-volume (MEFV, MIFV) curves and, according to the classic concept, a MEF50/MIF50 ratio of 0.9-1.1. However, since maximal expiratory static transrespiratory pressures (PEmax,stat) are clearly greater than the inspiratory ones (PImax,stat), ...

BACKGROUND: Ultrasound allows observation of the thickness of the diaphragm in the zone of apposition in vivo during relaxation and maximum inspiratory efforts. METHODS: Changes of diaphragm thickness were studied by B mode (two dimensional) ultrasound in 13 healthy men aged 29-54 years in the seated position. A high resolution ...

Increased abdominal mass in obesity should enhance normal gravitational effects on supine respiratory mechanics. We have examined respiratory impedance (forced oscillation over 4-26 Hz applied at the mouth during tidal breathing), maximum inspiratory and expiratory mouth pressures (MIP and MEP), and maximum effort flow-volume curves seated and supine in seven ...

We tested the hypothesis that increases in pressure in the abdomen (Pab) exerted by CO2 insufflation during laparoscopy would increase elastance (E) and resistance (R) of both the lungs and chest wall. We measured airway flow and airway and esophageal pressures of 12 anesthetized/paralyzed tracheally intubated patients during mechanical ventilation ...

The purpose of the present study was to determine the mechanical respiratory profile after the insertion of a catheter into the pleural cavity of anesthetized, paralyzed, mechanically ventilated rats, thus stimulating the common use of chest tubes in clinical situations. Using the method of end-inflation occlusion during constant inspiratory flow ...

Newborn infants with intractable respiratory failure who require extracorporeal membrane oxygenation (ECMO) experience diffuse pulmonary atelectasis shortly after initiation of ECMO. Atelectasis is likely due to the primary lung injury and the reduction of applied inspiratory ventilator pressure when the respirator settings are changed to the "rest settings." These pathophysiologic ...

The prevalence of abnormalities in lung elasticity in patients with asthma or chronic obstructive pulmonary disease (COPD) is still unclear. This might be due to uncertainties concerning the method of analysis of quasistatic deflation lung pressure-volume curves. Pressure-volume curves were obtained in 99 patients with moderately severe asthma or COPD. ...

Single-breath nitrogen wash-out and forced expirograms measured on two occasions, 8 years apart, were analysed for 24 subjects with varying degrees of peripheral airway involvement. Correlation analyses were carried out between closing volume in percentage of vital capacity (CV%), the slope of the alveolar plateau (phase III) and forced expiratory ...

In this study we examined the effects of hibernation on several aspects of pulmonary mechanics in golden mantled ground squirrels. Measurements were made on anesthetized animals that were active in late fall (FA, n = 7), maintained at 23 degrees C and normal photoperiod in mid-winter (WA, n = 0) ...

The decrease in functional residual capacity (FRC) with anesthesia may cause lung volume to decrease below closing volume, thereby impairing oxygenation. Increasing end-expiratory pressure (EEP) reexpands atelectatic areas in anesthetized, ventilated patients, but its effect on pulmonary mechanics is less well understood. We studied the effect of varying EEP on ...

Mechanical ventilation may promote overdistension-induced pulmonary lesions in patients with acute respiratory distress syndrome (ARDS). The static pressure-volume (P-V) curve of the respiratory system can be used to determine the lung volume and corresponding static airway pressure at which lung compliance begins to diminish (the upper inflection point, or UIP). ...

OBJECTIVE: In intubated, mechanically ventilated patients, inspiration is forced by externally applied positive pressure. In contrast, exhalation is passive and depends on the time constant of the total respiratory system. The expiratory time constant is thus an important determinant of mechanical ventilation. The aim of this study was to evaluate ...

We investigated the effects of the prone position on the mechanical properties (compliance and resistance) of the total respiratory system, the lung, and the chest wall, and the functional residual capacity (FRC) and gas exchange in 17 normal, anesthetized, and paralyzed patients undergoing elective surgery. We used the esophageal balloon ...

How pulmonary edema affects lung tissue and airway properties is not clear. From measurements of airway pressure and flow, we measured lung elastance (EL) and resistance (RL) in 5 anesthetized-paralyzed open-chested dogs during sinusoidal forcing in the frequency (f) and tidal volume (VT) ranges of normal breathing. RL was divided ...

Because of the anatomic association of an exceptionally bulky stomach with a striking compartmentation of the chest wall, leading to the most cranial insertion of the diaphragm among mammals, gastric overdistension in the bovine species offers a unique pathophysiological condition for the diaphragm. The purpose of the present study was ...

OBJECTIVE: To determine whether individuals with Prader-Willi syndrome (PWS) have abnormalities in pulmonary function as a result of thoracic muscle weakness. DESIGN: Testing of spirometry, flow-volume curves, lung volumes, and static respiratory pressures was performed in patients with PWS who are followed at the University of Connecticut. All tests were ...

OBJECTIVE: The relative dose potency of cumulative doses of terbutaline sulfate inhaled via Turbuhaler and via a pressurized metered dose inhaler was estimated with respect to lung efficacy and systemic effect. METHODS: The study was an open, crossover, randomized, multicenter study including 31 adult patients with asthma [forced expiratory volume ...

The aim of this work was to demonstrate that the three compartments of the lung T network and the chest wall impedance (Zcw) can be identified from input and transfer impedances of the respiratory system if the pleural pressure is recorded during the measurements. The method was tested in six ...

BACKGROUND: To increase the sensitivity of measurements of maximal inspiratory pressure (MIP) as a test of inspiratory muscle strength and endurance, software was developed to correct for variation in lung volume. METHODS: Using a body plethysmograph to determine absolute lung volume during each manoeuvre, values for MIP were expressed as ...

The essence of asthma is impairment of expiratory flow. Expiratory flow requires lung recoil forces to supply the driving pressure and to tether the airways open. Lung recoil forces arise within the parenchymal structures, particularly the air-liquid interface and elastin. Lung recoil is mainly elastic, but shows dissipative properties and ...

Chinese people have smaller total lung capacity (TLC) compared with Caucasians of similar age, sex and height. One possible reason would be a higher lung elastic recoil in Chinese. Most published values for lung elastic recoil viz static lung compliance (CLst), shape constant K, and maximal static transpulmonary pressure (PLmax) ...

A finite element model of the dog lung, heart and abdomen, consisting of three solid linearly elastic bodies, was developed to study the effects of gravity on the vertical stress distribution and lung volume in different body positions at functional residual capacity (FRC). The geometry of the lung was obtained ...

We studied the effects of head-to-foot acceleration (+Gz) on chest wall mechanics in five normal subjects seated in a human centrifuge. Results were compared with those previously obtained in the same subjects in microgravity during parabolic flights. In all subjects, end-expiratory abdominal pressure (Pga) and volume (Vab) increased with Gz. ...

Significant degrees of main-stem bronchial obstruction may not have a detectable effect on ventilation distribution at normal breathing frequencies. We determined the effect of graded left main-stem bronchial obstruction (area reduction of 50 and 70%) on the distribution of tidal volume (VT) and mean lung volume (VL) using radioactive 13NN ...

It has been demonstrated that respiratory resistance and elastance increase whilst the abdomen remains open during longitudinal laparotomy. We wished to determine whether changes also occur after abdominal closure in the same animal preparation. In 10 sedated, anaesthetized paralysed, and mechanically-ventilated rats (309 +/- 33 (SD) g), resistances and elastances ...

The purpose of this study was to investigate the effect of chronic renal failure (CRF) and continuous ambulatory peritoneal dialysis (CAPD) on respiratory muscle function. Global respiratory muscle strength was assessed by measuring mouth pressures during maximum static inspiration (PIMAX) near residual volume (RV) and expiration (PEMAX) near total lung ...

Pulmonary and airway mechanics were assessed in 30 patients with asthma bronchiale during a symptom-free interval, and with normal spirometry. Static expiratory pressure-volume (PV) curves and maximum expiratory flow-volume curves were obtained, and maximum flow-static recoil (MFSR) curves were drawn-up. In 11 patients elastic pressures were significantly lower than normal ...

It is a matter of controversy whether subjects who are heterozygous (PiMZ) for alpha 1-antitrypsin deficiency are at risk of developing pulmonary emphysema. To assess the role of MZ phenotype in the development of abnormal lung function the authors performed a 10 year follow-up study of 28 PiMZ subjects, compared ...

OBJECTIVE: To evaluate the effect of neuromuscular blockade on the elastic properties of the lungs, thorax, and total respiratory system in pigs anesthetized to suppress spontaneous breathing. DESIGN: Prospective, randomized, experimental study. SETTING: A research laboratory at a university medical center. SUBJECTS: Eight healthy, anesthetized pigs, weighing 22 to 25 ...

We quantitated the holes in alveolar walls in 11 nonemphysematous lungs and in 11 lungs with mild emphysema, all of which were removed at surgery. We found that in the nonemphysematous lungs, 94.1% of the holes were smaller than 10 microns in diameter and only 0.2% were larger than 20 ...

Although all the well-recognized muscles of expiration are paralyzed after traumatic transection of the lower cervical cord, tetraplegic subjects can still empty their lungs actively by contracting the clavicular portion of the pectoralis major. It is not known, however, whether contraction of this muscle bundle may raise pleural pressure enough ...

In a study among 194 male workers exposed to endotoxin-containing organic dust in animal feed mills, lung function was measured by flow volume curves and impedance measurements and respiratory symptoms were recorded by means of a validated questionnaire. The aims were to detect and localize airway obstruction caused by fodder ...

Gravity is known to influence the mechanical behavior of the lung and chest wall. However, the effect of sustained microgravity (mu G) on lung volumes has not been reported. Pulmonary function tests were performed by four subjects before, during, and after 9 days of mu G exposure. Ground measurements were ...

Initial observations on healthy term infants using the forced partial expiratory flow-volume technique with an inflatable jacket suggested that this technique was stimulating the Hering-Breuer deflationary reflex, a reflex which has not been systematically studied in man. To investigate this fully, esophageal pressure, jacket pressure, flow and volume at the ...

Studies on human infants suggested that thoracic gas volume (TGV) measured at end exhalation may not depict the true TGV and may differ from TGV measured from a series of higher lung volumes and corrected for the volume added. This was explained by gas trapping. If true, we should expect ...

The mixed expired nitric oxide (NO) production of the lungs of patients with primary pulmonary hypertension (PPH) and normal subjects was measured to determine the relationship between NO production and the diffusion capacity of the lung (KCO). Expired air was collected from eight patients with PPH and 20 healthy volunteers ...

Forced expiratory flow-volume (FEFV) curves can be generated from end-tidal inspiration in infants with use of an inflatable jacket. We have developed a technique to raise lung volume in the infant before generation of FEFV curves. Measurements of pressure transmission to the airway opening by use of static maneuvers have ...

The influence of suspended particulate matter, benzo(e) pyrene, benzo(e) pyrene and benzo(a) anthracene concentration on pulmonary lung functions ie, residual volume, total lung capacity, residual volume/total lung capacity, forced residual capacity were studied in 667 rubber factory workers during 1990-91. The respirable fraction of the particulate size (< 0.5 micron) ...

Progressive dyspnea that developed in a 52-year-old woman with a lifelong history of asthma did not respond to high-dose orally administered glucocorticoids. Initially, a diagnosis of allergic bronchopulmonary aspergillosis or hypersensitivity pneumonia was suggested as the cause of the worsening dyspnea. Pulmonary function tests demonstrated severe airway obstruction; substantial improvement ...