We measured respiratory input impedance (1-25 Hz) in mice and obtained parameters for airway and tissue mechanics by model fitting. Lung volume was varied by inflating to airway opening pressure (Pao) between 0 and 20 cm H2O. The expected pattern of changes in respiratory mechanics with increasing lung volume was ...

OBJECTIVES: To evaluate the use of specific compliance (static compliance/functional residual capacity) to adjust mean airway pressure, resulting in optimal gas exchange during high-frequency oscillatory ventilation in a surfactant-deficient newborn piglet. DESIGN: Prospective controlled animal study. SETTING: Laboratory. SUBJECTS: Eight newborn piglets at 5 days of age. BACKGROUND: High-frequency oscillatory ...

The administration of rapacuronium increases the risk of severe bronchospasm. There have been no studies of pulmonary function directly demonstrating airway constriction with rapacuronium in children. In this study, 10 ASA physical status I or II patients (aged 2-6 yr) were randomly divided into 2 equal groups, receiving either rapacuronium ...

The purpose of this prospective study was to measure lung attenuation at paired HRCT obtained at full inspiratory/expiratory position, to correlate with pulmonary function tests (PFTs) and to characterize different types of ventilatory impairment. One hundred fifty-five patients with and without pulmonary disease underwent paired HRCT obtained at full inspiratory/expiratory ...

STUDY OBJECTIVES: To determine the effect of emphysema and lung volume reduction surgery (LVRS) on diaphragm length (Ldi) and its capacity to generate transdiaphragmatic pressure (Pdi). DESIGN: Prospective clinical trial with a parallel group design. SETTING: Laboratory investigations in normal volunteers recruited by advertisement and in emphysema outpatients being evaluated ...

OBJECTIVE: The pressure-volume (P/V) curve has been proposed as a tool to adjust the ventilatory settings in cases of acute respiratory distress syndrome (ARDS). The aim of this study was to test the influence of P/V tracing methodology on the presence and value of the upper inflection point (UIP). METHODS: ...

Long term effects on respiratory function have been found in adult professional divers and have indicated the development of small-airway disease. The aim of this report was to investigate pulmonary lung function and breathing pattern of recreational divers, especially in young subjects. Pulmonary function was measured in 84 air divers ...

Recently, it has been suggested that peak expiratory flow (PEF) may be determined by the wave speed flow-limiting mechanism. In six normal male subjects (age = 33 +/- 8 years) performing expiratory forced vital capacity (FVC) maneuvers, a negative expiratory pressure (NEP) of -10 cm H2O was randomly applied at ...

STUDY OBJECTIVES: To assess the safety of frequent pressure-volume (PV) curve measurement in patients with acute lung injury (ALI)/ARDS. DESIGN: Prospective observational study. SETTING: Academic medical-surgical critical care unit. PATIENTS: Consecutive patients with ALI or ARDS. INTERVENTIONS: Static inspiratory PV curves of the respiratory system were determined twice on day ...

Cystic fibrosis (CF) eventually leads to hyperinflation linked to tidal expiratory flow limitation (FL) and ventilatory failure. Presence of FL was assessed at rest in 22 seated children and adults with CF (forced expiratory volume in one second (FEV1) range: 16-92% predicted), using both the negative expiratory pressure (NEP) technique ...

Lung volume reduction surgery (LVRS) has been shown to improve respiratory mechanics in selected patients with severe emphysema. This is thought to be due to an improvement in lung elastic recoil. This study was aimed at gaining further understanding about the effects of LVRS on respiratory mechanics and airway function. ...

The raised lung volume technique is increasingly used to measure forced expiratory maneuvers in infants. However, there is no consensus regarding the optimal airway inflation pressure (P(inf)) required for such maneuvers, or the influence of small changes in P(inf) within and between infants. The aim of this study was to ...

STUDY OBJECTIVES: To determine which respiratory function tests best predicted diaphragmatic strength in patients with amyotrophic lateral sclerosis. PATIENTS AND METHODS: Patients referred for pulmonary evaluation were included (n = 25) if they underwent measurement of transdiaphragmatic pressure (Pdi) and one or more of the following on the same day: ...

It is well known that bronchial obstruction causes an increase in negative pressure in the pleural cavity and is considered to be one of the factors giving rise to pleural fluid. We suggest that a reduction in the compliance of the lung parenchyma, whatever its cause (apart from bronchial obstruction), ...

New evidence requires a reinterpretation of the inflation pressure-volume curve and suggests that neither the lower nor the upper inflection point provides reliable information to determine safe ventilator settings in the acute respiratory distress syndrome. Recruitment probably continues throughout the inflation pressure-volume curve, and studies of the deflation pressure-volume curve, ...

Seventeen calves were inoculated intratracheally with Pasteurella multocida 0 on three consecutive days with 10 ml of an inoculum containing 10(9) colony forming units/ml per day per calf. Before the first inoculation and 24 hours after the third, each calf was examined non-invasively by means of a clinical examination, chest ...

BACKGROUND: High altitude pulmonary oedema (HAPE) that is severe enough to require urgent medical care is infrequent. We hypothesised that subclinical HAPE is far more frequent than suspected during even modest climbs of average effort. METHODS: We assessed 262 consecutive climbers of Monte Rosa (4559 m), before ascent and about ...

Preliminary feedback from physicians and pharmacists in Trinidad suggests that generic pressurized metered dose inhalers (pMDIs) of salbutamol are not as effective as Ventolin and that they have poor patient acceptance. This study was designed to compare the clinical efficacy and tolerance of two generic inhalers available in Trinidad (Asthalin ...

This review emphasizes the mechanisms responsible for maximum expiratory airflow limitation in acute and chronic persistent asthma. The phenomenon of acute but reversible loss of lung elastic recoil during acute asthma is reviewed, although no plausible physiologic explanations are offered. The authors have recently studied adult chronic, stable asthmatics with ...

The effect of pulmonary resection on the maximal emptying of the remaining lobes was examined in an open-chest preparation in normal canine lungs and in a unilobar papain emphysema model. The objectives were to determine whether, compared with when both lungs were deflated (BL), maximal emptying of the normal lower ...

The respiratory system is an elastic structure changing volume when pressures are generated by inspiratory or expiratory muscles. If the muscles are relaxed the respiratory system returns to its relaxation volume (Vr) (referred to in the pediatric literature as the elastic equilibrium volume [EEV]), which in normal subjects is the ...

BACKGROUND: We measured the three-dimensional ballistocardiogram (BCG) in a free-floating subject in sustained microgravity during spaceflight to test the usefulness of such measurements for future non-invasive monitoring of cardiac function, and to examine the effects of respiratory movement on the BCG in three axes. METHODS: Acceleration was measured using a ...

BACKGROUND: Short periods of sustained increase in airway pressures (Press(up)) are believed to re-open lung areas that collapsed upon induction of anaesthesia. Recruitment of alveolar surface is usually assessed in terms of changes in the pressure-volume (PV) curve. The purpose of this study was to analyse PV-curves before and after ...

Among the possible techniques to obtain the pressure-volume (P x V) curve at the bedside the low constant flow (CF) is the easiest and quickest one. However, the best value for CF to perform a good semi-static P x V curve is still to be determined. The purpose of this ...

A previous volume history should be established prior to pressure- volume (P-V) curve measurement, however the effect of the volume history and the peak inspiratory pressure (PIP) during the P-V measurement has not been explored. Lung injury was created by lavage in nine sheep (25-35 kg). After stabilization, four P-V ...

STUDY OBJECTIVES: Lung volume reduction surgery (LVRS) for emphysema has a variable effect on spirometry with improvement linked to increases in lung elastic recoil. The mechanism by which recoil increases following LVRS has not been described completely. This study examines preoperative and postoperative pulmonary function to describe a mechanism for ...

BACKGROUND: Bronchodilator reversibility testing is recommended in all patients with chronic obstructive pulmonary disease (COPD) but does not predict improvements in breathlessness or exercise performance. Two alternative ways of assessing lung mechanics-measurement of end expiratory lung volume (EELV) using the inspiratory capacity manoeuvre and application of negative expiratory pressure (NEP) ...

Whether the growth of the lungs in acromegaly is due to alveolar hypertrophy or alveolar hyperplasia is a subject of debate. To discriminate these hypotheses, we compared pulmonary distensibility and diffusing capacity among 11 patients with active acromegaly and 11 matched control subjects, evaluating the response of pulmonary distensibility and ...

The hypothesis that the changes in the respiratory system pressure- volume (PV) curve during pulmonary edema mainly reflect distal airway obstruction was investigated in rats. Normal rats had a well-defined upper inflection point (UIP) at low airway pressure. Airway occlusion by liquid instillation decreased compliance (Crs) and the volume (Vuip) ...

The aim of this paper is to evaluate the function of respiratory muscles in-patients with chronic moderate left ventricular failure (LVF), and its contribution to the pathophysiology of dyspnea and fatigue. We have studied 20 male patients with LVF, classes II and III of New York Heart Association (NYHA), mean ...

The beating heart naturally oscillates the lung because of the close juxtaposition between these organs producing cardiogenic oscillations in flow that can be measured at the mouth when the glottis is open. Correspondingly, if the mouth is occluded, the same phenomenon produces cardiogenic pressure oscillations that can be measured just ...

Our objectives were to characterize colonic viscoelastic properties of the human descending colon by assessing pressure-volume (P-V) relationships during barostatic balloon distension. In 16 healthy subjects, a balloon was inflated to 44 mmHg and then deflated to 0 mmHg in 4-mmHg steps at 10, 30, and 60 ml/min, allowing volume ...

Forced expiratory volumes are reduced in chronic obstructive pulmonary disease (COPD), mainly as a result of inflammatory and morphological changes in the small airways (with a diameter < 2 mm) and in the alveoli. However, it is difficult to detect minor changes in small airways by spirometry measurements. To study ...

Gravity-dependent changes of regional lung function were studied during normogravity, hypergravity, and microgravity induced by parabolic flights. Seven healthy subjects were followed in the right lateral and supine postures during tidal breathing, forced vital capacity, and slow expiratory vital capacity maneuvers. Regional 1) lung ventilation, 2) lung volumes, and 3) ...

PURPOSE: This study was designed to investigate whether rectal compliance is altered in females with obstructed defecation. METHODS: Eighty female patients with obstructed defecation and 60 control subjects were studied. Rectal compliance was measured with an "infinitely compliant" polyethylene bag. This bag was inserted in the rectum and inflated with ...

INTRODUCTION: Chronic measurement of respiratory function in the conscious monkey has been limited by the ability to monitor pleural pressure. Previous attempts to measure pleural pressure chronically in conscious animals have involved surgical implantation of pressure-sensitive catheters directly into the pleural cavity. The success of these techniques has been limited ...

BACKGROUND: Sarcoidosis is a systemic granulomatous disorder that is estimated to involve the skeletal muscles in up to 50% of patients. There is little information on the relationship among respiratory muscle strength, lung volumes, and the degree of dyspnea in patients with sarcoidosis. Design and patients: Lung function and maximal ...

Using the parenchymal marker technique, we measured pressure (P)-volume (P-V) curves of regions with volumes of approximately 1 cm3 in the dependent caudal lobes of oleic acid-injured dog lungs, during a very slow inflation from P = 0 to P = 30 cmH2O. The regional P-V curves are strongly sigmoidal. ...

The elastic pressure/volume (P/V) curve obtained by the multiple linear regression (MLR) technique using a new model, was compared with the quasi-static P/V points obtained by the rapid airway occlusion technique. Seven infants were studied during mechanical ventilation using a pressure controlled mode. The resistive pressure was subtracted from airway ...

The purposes of this cross-sectional study of 75 outpatients of a general oncology clinic were to assess the subjective and objective factors associated with dyspnea in cancer patients and to characterize factors that might contribute to respiratory muscle weakness demonstrated in a previous study. Patients with moderate to severe shortness ...

Understanding of the elastic pressure/volume (Pel/V) curve is still limited in health and disease. The aim of the present study was to elucidate the Pel/V curve and elastance of the respiratory system (ERS) lung (EL) and chest wall (ECW) in healthy pigs. Six young (20.8 kg) and seven adult (58.9 ...

Lung and chest wall mechanics were studied during fits of laughter in 11 normal subjects. Laughing was naturally induced by showing clips of the funniest scenes from a movie by Roberto Benigni. Chest wall volume was measured by using a three-dimensional optoelectronic plethysmography and was partitioned into upper thorax, lower ...

Spirometry and pulmonary mechanics were measured pre- and postoperatively in 37 patients undergoing bilateral lung volume reduction surgery (LVRS). The relative contributions of changes in compliance (CL), recoil pressures (PTLC), small airway conductance (Gu), and airway closing pressures (Ptm') to changes in expiratory flows were examined with a Taylor series ...

Pulmonary fibrosis is a common complication in progressive systemic sclerosis (PSS). Physical examination and/or routine pulmonary function tests can, however, detect only relatively advanced disease. We assessed the utility of static lung pressure-volume analysis in detecting lung involvement in patients of PSS without obvious clinical, radiological or spirographic evidence of ...

Expiratory muscle strength is a determinant of cough function. Mouth pressures during a maximal static expiratory effort (PE,max) are dependent on patient motivation and technique and low values are therefore difficult to interpret. This study hypothesized that a short, sharp and maximal expiration through a narrow aperture, a "whistle", might ...

The pressure-volume curve of the respiratory system is a physiological method used for diagnotic purposes to describe the static mechanical properties of the respiratory system. A renewal of interest in the pressure-volume curve has recently appeared because of experimental evidence regarding the information conveyed by the curve, a better understanding ...

The response to deep inspiration (DI) has been reported in terms of specific airway conductance (SGaw) pre- and post-DI, and by comparing forced expiratory flows following both maximal and partial inspiration (M/P ratio). The lung volume at which M/P has been obtained has varied between studies. We have investigated how ...

BACKGROUND: The computerized noninvasive measurement of respiratory mechanics enables new prospects in the study of respiratory physiopathology in surgical repair of large incisional hernias. STUDY DESIGN: We studied 10 patients with COPD ventilated with a Servo Ventilator 900C. We measured inspiratory flow by means ofa pneumotacograph, the volume by integrating ...

BACKGROUND: Dopamine exerts inhibitory and excitatory effects on different systems. Its effect on human bronchial tone is controversial. It has been reported that dopamine has no acute effect on human airways from normal subjects or those with asthma background. However, inhaled or infused dopamine decreased histamine-induced bronchoconstriction in both normal ...

The impact of noninvasive positive-pressure ventilation (NIPPV) on pulmonary function studies, quality of life, and survival was assessed in patients with amyotrophic lateral sclerosis. NIPPV did not change the rate of decline of the forced vital capacity (FVC) and forced expiratory volume in the first second (FEV(1)) (2.31 and 2.09 ...