The clinical application of transdiaphragmatic twitch pressure (Pdi,tw) response to phrenic nerve stimulation has been hindered by the requirement for placement of oesophageal and gastric balloons. Investigators have reported that mouth twitch pressure (Pmo,tw) estimates Pdi,tw accurately at lung volumes above and below functional residual capacity (FRC). However, it is ...

The effects of inspiratory flow and inflation volume on the mechanical properties of the respiratory system in eight sedated and paralyzed postoperative morbidly obese patients (aged 37.6 +/- 11.8 yr who had never smoked and had normal preoperative seated spirometry) were investigated by using the technique of rapid airway occlusion ...

A canine model of unilobar papain-induced emphysema was used to examine the extent to which differences in alveolar pressures (PA) would develop between an emphysematous right lower lobe (RLL) and normal left lower lobe (LLL) during forced vital capacity (FVC) deflation. RLL and LLL PA (PARLL and PALLL, respectively) were ...

In emphysema, the diaphragm shortens by losing sarcomeres. We hypothesized that unless capillaries undergo a similar shortening, capillary geometry must be altered. Without quantifying this geometry, capillary length and surface area per fiber volume, which are critical measurements of the structural potential for blood-tissue exchange, cannot be resolved. Five months ...

Airway hyperresponsiveness is characterized by an increase in sensitivity and excessive airway narrowing to inhaled bronchoconstrictor stimuli. There is experimental evidence that maximal airway narrowing is related to lung elasticity in normal and asthmatic subjects. We hypothesized that reduced lung elasticity by parenchymal destruction increases the level of maximal airway ...

OBJECTIVE: To analyze the relationship between disease progression, pulmonary volumes, respiratory muscle strength (maximum inspiratory [MIP] and expiratory [MEP] pressure), and arterial blood gases for patients with Duchenne muscular dystrophy (DMD). DESIGN: An inception cohort study of pulmonary volumes, MIPs, and MEPs, correlated with age and PaCO2 levels and with ...

In an open, randomized crossover study two different types of dry powder inhalers (DPIs) were compared. Twenty-five adult asthmatic patients inhaled a single dose of 200 micrograms of salbutamol (CAS 18559-94-9) on two separate days. Salbutamol was administered either from a novel multidose DPI (Easyhaler, test DPI) or from another ...

Maturational changes in the specific compliance could potentially contribute to the development or clinical presentation of respiratory diseases in infants and children. Changes in the specific compliance during development and its structural basis have been well characterized, but changes in bronchial compliance and the mechanisms involved have received little attention. ...

This study aimed to determine the relationship between pulmonary function, respiratory muscle function and neurological function in multiple sclerosis (MS). Sixty patients (27 males and 33 females) aged 27-75 yrs (mean +/- SD 48 +/- 12 yrs) were prospectively studied. The Kurtzke Expanded Disability Status Scale (EDSS; range 0-10) score ...

The purpose of this study was to examine ventilatory muscle strength as represented by static respiratory pressures in 30 tetraplegic patients with a complete lesion between the fifth and the eighth cervical vertebrae. The Inspiratory/Expiratory Pressure Meter was used to obtain maximum static expiratory mouth pressure (PEmax) and maximum static ...

Workers of a chemical plant department producing dust and liquid pesticides (37 males and 17 females) exposed to dust containing free silica, organic solvents and active substances, among others: organophosphate compounds, pyrethroids, triazines, carbamates and dithiocarbamates, 2,4-D, captan, carboxine, carbendazim and dodine were studied. Spirometric investigations, including evaluation of vital ...

STUDY OBJECTIVE: To determine pulmonary function test (PFT) profile and respiratory muscle strength (RMS) of a group of obese individuals who did not have evidence of obstructive airway disease or other underlying diseases affecting their respiratory system. DESIGN: Prospective, open. SETTING: PFT laboratory, VA Medical Center. PARTICIPANTS: Sixty-three consecutive obese ...

Respiratory mechanics was studied in 11 rabbits at tidal volumes (VT) of 6.7, 10, and 20 ml/kg. Flow interruptions were performed during the full respiratory cycle. The viscoelastic pressure (Pve) was measured as the dynamic elastic pressure (Pel(dyn)) after flow cessation minus the static elastic pressure (Pel(st)). Static elastic and ...

In a 3-year survey, respiratory symptoms, spirometry, and methacholine reactivity were measured annually in welders (n = 51) and non-welder controls subjects (n = 54) to determine whether welding-related symptoms are associated with accelerated decline in lung function or changes in airway reactivity. In the cross-workshift study, maximal midexpiratory flow ...

OBJECTIVE: To investigate the mechanism of airflow limitation before and 6 and 12 months after targeted emphysematous resection in 10 male patients aged 67 +/- 8 years (mean +/- SD) with very severe COPD undergoing bilateral thoracoscopic stapling techniques. DESIGN: Lung function, including static lung elastic recoil, was measured 2 ...

PURPOSE: The literature describing the pulmonary mechanisms of increased PA-PaO2 during general anaesthesia was examined to define the role of airway closure and sub-radiological atelectasis. SOURCE: A Medline search was designed to include articles dealing with the stated purpose, which is thus selective rather than a meta-analysis. The MeSH consisted ...

We have described impairment of the respiratory function in adult patients with childhood-onset 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 before and after 6 and 12 months of recombinant GH treatment. Ten ...

Ventilatory mechanics were measured at rest and during steady-state (25%, 50%, 75%) and maximal exercise (W-Max) on a cycle-ergometer in eight adult patients (FEV1 22 to 114% of predicted) with cystic fibrosis (CF). Tidal flow-volume loops were measured at rest and during exercise and placed within the maximal pre- and ...

To understand the pathophysiology of dyspnoea in patients with hyperthyroidism, lung function, maximum inspiratory, expiratory respiratory muscle pressures (MIP and MEP) and intensity of dyspnoea (after six minutes walking test) were recorded in 12 consecutive patients with active Graves' disease. Reassessment was done after achieving euthyroidism with 8-12 wk of ...

Recently, lung volume reduction [LVR] removal of about 20% of lung volume), has been performed to treat severe emphysema. Little is known, however, about the mechanism and time course of functional improvement, and the reasons that such patients can be tracheally extubated very early. Therefore, we studied changes in ventilatory ...

We prospectively investigated the mechanism of airflow limitation before and after targeted emphysematous resection in 12 consecutively studied adult patients 68 +/- 4 yr of age (mean +/- SD) with very severe COPD undergoing bilateral thoracoscopic stapling techniques. Lung function, static lung elastic recoil, and airway conductance was measured 2 ...

Intrinsic positive end-expiratory pressure (PEEPi) due to dynamic hyperinflation has been measured as a plateau airway opening pressure during airway occlusion (PEEPi,stat). PEEPi has also been dynamically determined as a fall in esophageal pressure (Pes) before the inspiratory flow starts (PEEPi,dyn). The aims of the current study were to systematically ...

Using the parenchymal marker technique in normal anesthetized dogs, we compared the dynamics of regional lung expansion between two ventilation strategies designed to increase mean thoracic volume. Dynamic hyperinflation (DH was produced by ventilating the lungs at a rate of 50 breaths/min and with a duty cycle of 0.5. Static ...

Respiratory muscle weakness is the primary cause of respiratory dysfunction in neuromuscular disease (NMD), but structural abnormalities of the chest wall also play a role. In adults with NMD, restrictive lung disease is in part caused by reduced chest wall compliance (C(W)), believed to reflect stiffening of connective tissue resulting ...

Lung volume reduction surgery (LVRS) in patients with severe lung emphysema restores the thoracic configuration to a more normal functional capacity. The aim of this study was to investigate whether reduction in intrathoracic volume by LVRS improves the inspiratory muscle force generation of the respiratory pump. Pulmonary function tests, maximal ...

Pulmonary function changes in interstitial lung disease are characterized by loss of lung volume, increase in ratio of forced expiratory volume in 1 second to forced vital capacity, and decrease in carbon monoxide diffusion capacity. Recent developments in the assessment of respiratory mechanics in infiltrative lung disease have elucidated volume ...

We investigated the effects of prone position on functional residual capacity (FRC), the mechanical properties (compliance and resistance) of the total respiratory system, lung and chest wall, and the gas exchange in 10 anesthetized and paralyzed obese (body mass index more than 30 kg/m2) patients, undergoing elective surgery. We used ...

To assess the airway response to inhaled tobramycin we measured flow volume curves in 12 patients with cystic fibrosis. Immediately and/or 2 min after tobramycin inhalations there was a significant fall in lung function regardless of the concentration used; isotonic saline caused similar obstruction but not a complete cessation of ...

OBJECTIVE: To determine the contributions of (1) chest wall (Pcw) and (2) lung elastic recoil pressure (PL) to (3) total elastic recoil pressure exerted by the respiratory system (Prs) in 18 patients (12 men) aged 66 +/- 6 years (mean +/- 1 SD) with severe emphysema who underwent video-assisted thoracoscopic ...

In five normal men, we divided the rib cage into lung-apposed [pulmonary rib cage (RCp)] and diaphragm-apposed [abdominal rib cage (RCab)] compartments and calculated their absolute cross-sectional areas (Arc,p and Arc,ab) by anteroposterior and lateral dimensions measured by magnetometry. Distortion was quantified as the displacement of RCp and RCab produced ...

BACKGROUND: A diaphragmatic phonomyogram (PMG) evoked by maximal phrenic nerve stimulation at end expiratory lung volume (FRC) has been previously described as a good index of changes in diaphragmatic contractility with fatigue. A study was undertaken to assess whether this conclusion could be extended to different lung volumes. METHODS: Diaphragmatic ...

PURPOSE: To test the hypothesis that a physiological compensatory mechanism maintains respiratory gas exchange during normovolaemic haemodilution. METHODS: Pulmonary gas exchange capacity was evaluated in seven healthy subjects by measuring the lung diffusion of carbon monoxide (DLCO). During the measurement, various breath-holding times, inspiratory volumes, and sitting or supine positions, ...

Forced expiratory maneuvers generated by rapid thoracic compression have been used to assess airway function in infants. It remains unclear whether flow limitation can be achieved in healthy infants because low pressure transmission across the chest wall and inspiratory effort may limit the maximum transpulmonary pressure developed during the maneuver. ...

An alveolar capsule oscillation technique was used to determine 1) the lobe pressure and volume at which airways close and reopen, 2) the effect of expiration rate on closing volume and pressure, 3) the phase in the breathing cycle at which airway closure occurs, and 4) the site of airway ...

Functional residual capacity (FRC) is an important oxygen reserve that is often depleted in acute respiratory failure. Recent interest in the mechanisms of liquid ventilation and limited experience in measuring FRC in paralyzed, mechanically ventilated, normal and lung-injured animal models have mandated development of accurate laboratory techniques. Eight sheep, from ...

The diffusing capacity for carbon monoxide is partially dependent on lung volume at which it is measured. As a consequence, the diffusing capacity for carbon monoxide is often indexed to the simultaneously measured lung volume (VA), giving rise to the term DL/VA. This reflects the diffusing capacity of carbon monoxide ...

STUDY OBJECTIVE: To test whether the Trendelenburg ("head-down") or reverse Trendelenburg ("head-up") postures change lung and chest wall mechanical properties in a clinical condition. DESIGN: Unblinded study, each patient serving as own control. SETTING: University of Maryland at Baltimore Hospital, Baltimore, Maryland. PATIENTS: 15 patients scheduled for laparoscopic surgery. INTERVENTIONS: ...

The volume dependence of respiratory elastance makes it difficult to recognize actual changes in lung and chest wall elastic properties in artificially ventilated subjects. We have assessed in six anesthetized, tracheotomized, and paralyzed rabbits whether reliable information on the static pressure-volume (PV) curve could be obtained from recordings performed during ...

BACKGROUND: Pulmonary function may improve after surgical resection of the most severely affected lung tissue (lung-reduction surgery) in patients with diffuse emphysema. The basic mechanisms responsible for the improvement, however, are not known. METHODS: We studied 20 patients with diffuse emphysema before and at least three months after either a ...

The aim of this prospective study was to confirm whether and when a fall in gas transfer occurs following heart transplantation (HT); and to examine the potential relationship between gas transfer and haemodynamic change, immuno-suppression and cytomegalovirus (CMV) infection. The lung physiology of 34 heart transplant recipients (HTR) and 14 ...

Parenchymal markers were placed in the left caudal lobes of anesthetized dogs, and the three-dimensional positions of the markers were tracked by biplane videofluoroscopy during expiration from total lung capacity (TLC) to approximately 30% TLC at steady expiratory flows of 0.3-7% TLC/s. Regional volumes of samples of parenchyma with volumes ...

BACKGROUND: Recognition of the potential for ventilator-associated lung injury has renewed the debate on the importance of the inspiratory flow pattern. The aim of this study was to determine whether a ventilatory pattern with decelerating inspiratory flow, with the major part of the tidal volume delivered early, would increase functional ...

To understand how the parietal pleurae affect the mechanical behavior of the human respiratory system after the chest wall is opened by median sternotomy, we studied 18 anesthetized/paralyzed patients immediately before coronary artery bypass grafting surgery. Elastances and resistances of the total respiratory system (ETr, Rrs) were calculated from measurements ...

Previously we have reported that large increases in lung and chest wall elastances as well as lung resistance occur with abdominal insufflation of carbon dioxide during laparoscopic surgery. To examine whether these effects were reversible with abdominal deflation, we calculated lung and chest wall elastances and resistances from measurement of ...

Rapid thoracoabdominal compression (RTC) and forced deflation (FD) allow the examination of maximal expiratory flow-volume (MEFV) curves in animals and human infants unable to generate a voluntary maximal expiratory maneuver. We compared flows generated by these two techniques and by constructing isovolume pressure-flow (IVPF) curves examined each method's potential to ...

Physical training in water might be included in a comprehensive pulmonary rehabilitation programme, but data on the feasibility and safety of this technique in chronic obstructive pulmonary disease (COPD) patients are lacking. We studied cardiorespiratory parameters of 20 stable COPD patients (10 with forced expiratory volume in one second (FEV1) ...

The forced vital capacity (FVC) maneuver is the most common lung function test. One of its major prerequisites is that it be performed with sufficient effort to achieve the maximal flows that are due to expiratory flow limitation. To verify this, in nine normal subjects, short (0.25-s) pulses of negative ...

The parenchymal marker technique was used to measure regional tidal volumes of samples of lung parenchyma in four open-chest supine dogs. Radiopaque markers that had been implanted in the lower lobe were tracked by biplane video fluoroscopy during sinusoidal volume oscillations at tidal volumes of approximately 20% of total lung ...

OBJECTIVE: To study the relative contribution of the lung and the chest wall on the total respiratory system mechanics, gas exchange, and work of breathing in sedated-paralyzed normal subjects and morbidly obese patients, in the postoperative period. SETTING: Policlinico Hospital, University of Milan, Italy. METHODS: In ten normal subjects (normal) ...

Total lung capacity (TLC), inspiratory capacity (IC), functional residual capacity (FRC), and deflation pressure-volume (P-V) curves were studied in 16 intubated neonates (540-3300 g), 10 with severe respiratory distress syndrome (RDS) and 6 air-ventilated with normal chest radiograms. FRC was measured using washout of a tracer gas (sulfur hexafluoride), and ...