Search results for "Respiratory Mechanics"
showing 10 items of 43 documents
Magnetic resonance imaging of dissolved hyperpolarized 129Xe using a membrane-based continuous flow system.
2009
Abstract A technique for continuous production of solutions containing hyperpolarized 129Xe is explored for MRI applications. The method is based on hollow fiber membranes which inhibit the formation of foams and bubbles. A systematic analysis of various carrier agents for hyperpolarized 129Xe has been carried out, which are applicable as contrast agents for in vivo MRI. The image quality of different hyperpolarized Xe solutions is compared and MRI results obtained in a clinical as well as in a nonclinical MRI setting are provided. Moreover, we demonstrate the application of 129Xe contrast agents produced with our dissolution method for lung MRI by imaging hyperpolarized 129Xe that has been…
Spatial and temporal heterogeneity of ventilator-associated lung injury after surfactant depletion.
2008
Volutrauma and atelectrauma have been proposed as mechanisms of ventilator-associated lung injury, but few studies have compared their relative importance in mediating lung injury. The objective of our study was to compare the injury produced by stretch (volutrauma) vs. cyclical recruitment (atelectrauma) after surfactant depletion. In saline-lavaged rabbits, we used high tidal volume, low respiratory rate, and low positive end-expiratory pressure to produce stretch injury in nondependent lung regions and cyclical recruitment in dependent lung regions. Tidal changes in shunt fraction were assessed by measuring arterial Po2 oscillations. After ventilating for times ranging from 0 to 6 h, lu…
Inspiratory Effort and Respiratory Mechanics in Patients with Acute Exacerbation of Idiopathic Pulmonary fibrosis: A Preliminary Matched Control Stud…
2022
Background: Patients with acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF) may experience severe acute respiratory failure, even requiring ventilatory assistance. Physiological data on lung mechanics during these events are lacking. Methods: Patients with AE-IPF admitted to Respiratory Intensive Care Unit to receive non-invasive ventilation (NIV) were retrospectively analyzed. Esophageal pressure swing (ΔPes) and respiratory mechanics before and after 2 hours of NIV were collected as primary outcome. The correlation between positive end-expiratory pressure (PEEP) levels and changes of in dynamic compliance (dynCRS) and PaO2/FiO2 ratio was assessed. Further, an exploratory compar…
Bronchial asthma and personality dimensions: a multifaceted association.
1994
Personality dimensions seem to play an important role in chronic diseases by maintaining or increasing the patient's physical complaints. This study examines in bronchial asthma: (a) the relationships among clinical data, baseline lung function, and personality traits; and (b) the patient's characteristics related to the physician's judgement about his or her asthma severity. Five questionnaires measuring anxiety, depression, self-consciousness, and subjective symptoms were completed by 51 asthmatic patients. Responses to questionnaires and clinical and demographic data were factor-analyzed. Factor analysis revealed that the physician's severity judgement is based on elderly age, high score…
Effect of age upon airway obstruction and reversibility in adult patients with asthma.
1998
In a cross-sectional study we evaluated the effect of aging (separately from that of duration of disease) on airway obstruction and reversibility by comparing two groups of non-smoker patients with asthma.We compared two groups of patients: group A, which had 50 subjects (8 men and 42 women) aged 59.7+/-4.6 years (mean +/- SD), and group B, comprised of 51 subjects (19 men and 32 women) who were 35.7+/-7.4 years old. The groups were selected because of comparable baseline degree of obstruction (FEV1 % of predicted, 67.8+/-20.3 in group A; 73.0+/-19.6 in group B, NS) and duration of the disease (14.0+/-11.7 years vs 11.2+/-9.1, NS). Spirometric examination, with a bronchodilator test, was pe…
A Bench Evaluation of Eight Home-Care Ventilators
2021
BACKGROUND: The growing number of patients on home mechanical ventilation has driven considerable progress in the performance and functionality of ventilators, with features comparable with those used in the ICU. However, a publication gap exists in the evaluation and comparison of their performance and each ventilator choice depends on machine characteristics defined by manufacturers. METHODS: We bench tested 8 home-care ventilators that are currently available: Monnal T50, EOVE EO-150, Puritan Bennet 560, Weinmann, PrismaVent 50, Trilogy Evo, Astral 150, and Vivo 60 by using an active lung model. These devices were tested under 18 experimental conditions that combined 3 variables: respira…
Observation of ventilation-induced Spo(2) oscillations in pigs: first step to noninvasive detection of cyclic recruitment of atelectasis?
2010
High arterial partial oxygen pressure (Pao(2)) oscillations within the respiratory cycle were described recently in experimental acute lung injury. This phenomenon has been related to cyclic recruitment of atelectasis and varying pulmonary shunt fractions. Noninvasive detection of Spo(2) (oxygen saturation measured by pulse oximetry) as an indicator of cyclic collapse of atelectasis, instead of recording Pao(2) oscillations, could be of clinical interest in critical care. Spo(2) oscillations were recorded continuously in three different cases of lung damage to demonstrate the technical feasibility of this approach. To deduce Pao(2) from Spo(2), a mathematical model of the hemoglobin dissoci…
Structural and functional evidence for the scaffolding effect of alveolar blood vessels
2017
A contribution of pulmonary blood distension to alveolar opening was first proposed more than 100 years ago. To investigate the contribution of blood distension to lung mechanics, we studied control mice (normal perfusion), mice after exsanguination (absent perfusion) and mice after varying degrees of parenchymal resection (supra-normal perfusion). On inflation, mean tracheal pressures were higher in the bloodless mouse (4.0α2.5 cmH2O); however, there was minimal difference between conditions on deflation (0.7α0.9 cmH2O). To separate the peripheral and central mechanical effects of blood volume, multi-frequency lung impedance data was fitted to the constant-phase model. The presence or abse…
Exploring Associations Between Respiratory Mechanics and Survival in Immunocompromised Patients With ARDS.
2020
Thanks to improvements in organ support strategies and to advances in the treatment of solid and hematological tumors, outcome of immunocompromised patients requiring ICU admission has improved impressively over the last decade . For this reason, the number of immunocompromised patients admitted to the ICU and deemed candidates for invasive therapies is steadily increasing. Acute respiratory failure (ARF) is the leading cause of hospital and ICU admission, but the optimal first-line reatment of respiratory failure in these patients remains to be determined
Influence of different interfaces on synchrony during pressure support ventilation in a pediatric setting: a bench study
2015
BACKGROUND: In adults and children, patient-ventilator synchrony is strongly dependent on both the ventilator settings and interface used in applying positive pressure to the airway. The aim of this bench study was to determine whether different interfaces and ventilator settings may influence patient-ventilator interaction in pediatric models of normal and mixed obstructive and restrictive respiratory conditions. METHODS: A test lung, connected to a pediatric mannequin using different interfaces (endotracheal tube [ETT], face mask, and helmet), was ventilated in pressure support ventilation mode testing 2 ventilator settings (pressurization time [Timepress]50%/cycling-off flow threshold [T…