BACKGROUND Most portable bi-level positive airway pressure devices are not equipped with air-oxygen blenders for precisely regulating oxygen concentrations, and supplemental oxygen must be added to increase the F(IO2). Very few studies have investigated the factors that affect F(IO2), and their conclusions have been inconsistent. We investigated in vitro noninvasive ventilation (NIV) parameters...

1. Airway resistance was measured close to functional residual capacity before and after a full inhalation of total lung capacity, as well as before and after a full exhalation to residual volume. 2. The effects of these volume manoeuvres upon airway resistance (and associated lung volume) were determined in four resting normal male subjects and in six normal men during experimentally induced b...

INTRODUCTION Spirometry is the basic method used to diagnose and monitor obstructive diseases. Spirometric tests are performed in more and more people of advanced age (more than 65 years old). The objective of the study was to assess the quality of spirometry (measurement of the flow-volume curve) in subjects of the aforementioned age group, with reference to applicable quality criteria specifi...

was identifi ed in 1 sample. These results enabled us to compare DHPS genotypes for 6 pairs of samples. A full match was found for these 6 pairs. DHPS and ITS genotype matches were found for 4 pairs. Several lines of evidence suggest that P. jirovecii is exhaled by infected patients and transmitted by the airborne route to susceptible persons (4). In the study reported here, ITS or DHPS genotyp...

The exchange characteristics of a highly soluble gas with the pulmonary airways during a single-exhalation maneuver were analyzed using a mathematical model previously described by our group (M. E. Tsu et al. Ann. Biomed. Eng. 16: 547-571, 1988). The model integrates the simultaneous exchange of water, heat, and a soluble gas with the pulmonary airways. The purpose of this paper is to provide e...

Radon (222Rn) is a naturally occurring radioactive gas that originates from the decay of radium (226Ra) in the primordial uranium (238U) decay series. As a noble gas, it easily migrates through inter-granular spaces; then, because of advection, diffusion and convection with other gasses or with water, it moves through fi ssures and faults until it reaches the outdoor atmosphere. Its half-life i...

The diffusing capacity, DL, is a critical physiological parameter of the lung used to assess gas exchange clinically. Most models developed to analyze experimental data from a single breath maneuver have assumed a well-mixed or uniform alveolar region, including the clinically accepted Jones-Meade method. In addition, all previous models have assumed a constant DL, which is independent of alveo...

Current techniques to estimate nitric oxide (NO) production and elimination in the lungs are inherently nonspecific or are cumbersome to perform (multiple-breathing maneuvers). We present a new technique capable of estimating key flow-independent parameters characteristic of NO exchange in the lungs: 1) the steady-state alveolar concentration (C(alv,ss)), 2) the maximum flux of NO from the airw...

PURPOSE To image respiratory dynamics and three-dimensional (3D) ventilation during inhalation, breath-hold, and exhalation for evaluation of obstructive lung disease using a single dose of hyperpolarized (HP) He-3 during MRI. MATERIALS AND METHODS A single 2D-3D projections inside Z encoding (PRIZE)-2D acquisition was performed that consisted of a rapid 2D radial acquisition phase during inh...

We aimed to optimize internal margin (IM) determination for respiratory-gated radiotherapy using end-expiratory phase assessments using a motion phantom. Four-dimensional computed tomography (4D CT) data were acquired using a GE LightSpeed RT CT scanner, a respiratory-gating system, and a motion phantom designed to move sinusoidally. To analyze the accuracy of 4D CT temporal resolution, a 25.4 ...