Read by QxMD icon Read


Mehrdad Behnia, Courtney M Wheatley, Alberto Avolio, Bruce D Johnson
Background: Factors limiting exercise in patients with COPD are complex. With evidence for accelerated pulmonary vascular aging, destruction of alveolar-capillary bed, and hypoxic pulmonary vasoconstriction, the ability to functionally expand surface area during exercise may become a primary limitation. Purpose: To quantify measures of alveolar-capillary recruitment during exercise and the relationship to exercise capacity in a cohort of COPD patients. Methods: Thirty-two subjects gave consent (53% male, with mean ± standard deviation age 66±9 years, smoking 35±29 pack-years, and Global Initiative for Chronic Obstructive Lung Disease (GOLD) classification of 0-4: 2...
2017: International Journal of Chronic Obstructive Pulmonary Disease
Howard Stein, Kimberly Firestone, Peter C Rimensberger
The electrical activity of the diaphragm (Edi) is measured by a specialized nasogastric/orogastric tube positioned in the esophagus at the level of the crural diaphragm. Neurally adjusted ventilatory assist (NAVA) uses the Edi signal as a neural trigger and intrabreath controller to synchronize mechanical ventilatory breaths with the patient's respiratory drive and to proportionally support the patient's respiratory efforts on a breath-by-breath basis. NAVA improves patient-ventilator interaction and synchrony even in the presence of large air leaks, and might therefore be an optimal option for noninvasive ventilation in neonates...
September 2012: Clinics in Perinatology
Victy Y W Wong, Stewart Y Tung, Alice W Y Ng, Francis A S Li, Joyce O Y Leung
PURPOSE: In this article, the breath-hold and gating concepts were combined for application of lung cancer radiation treatment. The tumor movement was immobilized based on deep inspiration breath hold (DIBH), in which the breath-hold consistency and stability were monitored by infrared (IR) tracking and controlled by gating with a predefined threshold. The authors' goal is to derive the benefits from both techniques, namely, the minimized treatment margin and the known advantages of deep inspiration...
September 2010: Medical Physics
N Bougaci, F Costes, L Bertoletti
The in vivo study of the pulmonary microcirculation, and its recruitment, is currently not common, although it may be of interest. The intrabreath analysis (IB) of the carbon monoxide (CO) and acetylene (C(2)H(2)) diffusion is used to study the transfer of CO (TLCO) and the pulmonary capillary blood flow (Qs), particularly during exercise. The evolution of the Qs during different stages of exercise has never been reported in healthy subjects. The authors measured the Qs and TL at rest and then during and after short bouts of exercise in 12 healthy subjects...
June 2010: Revue de Pneumologie Clinique
Shuyi Ma, Ariel Hecht, Janos Varga, Mehdi Rambod, Sarah Morford, Shinichi Goto, Richard Casaburi, Janos Porszasz
During heavy exercise in chronic obstructive pulmonary disease (COPD), dynamic airways compression leads to a progressive fall in intrabreath flow. This is manifested by concavity in the spontaneous expiratory flow-volume (SEFV) curve. We developed a method to quantify the SEFV curve configuration breath-by-breath during incremental exercise utilizing a computerized analysis. The flow signal was digitized at 100Hz. For each breath's SEFV curve, points of highest flow (V (max)) and end-expiration (V (EE)) were identified to define a rectangle's diagonal...
March 2010: Respiratory Medicine
Gaea Schwaebe Moore, Stewart C Wong, Chantal Darquenne, Tom S Neuman, John B West, G Kim Prisk
Venous gas bubbles occur in recreational SCUBA divers in the absence of decompression sickness, forming venous gas emboli (VGE) which are trapped within pulmonary circulation and cleared by the lung without overt pathology. We hypothesized that asymptomatic VGE would transiently increase ventilation-perfusion mismatch due to their occlusive effects within the pulmonary circulation. Two sets of healthy volunteers (n = 11, n = 12) were recruited to test this hypothesis with a single recreational ocean dive or a baro-equivalent dry hyperbaric dive...
November 2009: European Journal of Applied Physiology
A Charloux, I Enache, R Richard, M Oswald-Mammosser, E Lonsdorfer-Wolf, F Piquard, B Geny
The aims of this study were to evaluate the feasibility of successive diffusing capacity of the lung for carbon monoxide (DLCO) measurements during two different exercise tests (upright cycling), and to compare the relationships between DLCO and pulmonary blood flow (Qc). Eight healthy subjects performed an incremental test (1-min step) and a strenuous 30-min intermittent-work exercise test (4 min at low and 2 min at high workload). Intrabreath DLCO and Qc were calculated by assessing the uptake of CO and C2H2 during exhalation...
February 2010: Scandinavian Journal of Medicine & Science in Sports
Cynthia Eccles, Kristy K Brock, Jean-Pierre Bissonnette, Maria Hawkins, Laura A Dawson
PURPOSE: To measure the intrabreath-hold liver motion and the intrafraction and interfraction reproducibility of liver position relative to vertebral bodies using an active breathing coordinator (ABC) in patients with unresectable liver cancer treated with hypofractionated stereotactic body radiation therapy (SBRT). METHODS: Tolerability of ABC and organ motion during ABC was assessed using kV fluoroscopy in 34 patients. For patients treated with ABC, repeat breath-hold CT scans in the ABC breath-hold position were acquired at simulation to estimate the volumetric intrafraction reproducibility of the liver relative to the vertebral bodies...
March 1, 2006: International Journal of Radiation Oncology, Biology, Physics
Yuh-Chin T Huang, Sharon R O'brien, James Vredenburgh, Rodney J Folz, Neil R Macintyre
The single exhalation analysis of carbon monoxide, acetylene, and methane allows the determination of intrabreath (regional) DL, pulmonary capillary blood flow and ventilation inhomogeneities during rest and exercise. We reasoned that this technique might be more sensitive in detecting regional pulmonary capillary abnormalities than resting single breath DL (DL(sb)). We selected a group of breast cancer patients in high-dose chemotherapy (HDCT) protocols who were at risk for pulmonary injury. We grouped the patients into pre-HDCT and post-HDCT, and used resting DL(sb) to further categorize the latter into those with and without pulmonary injury...
July 2006: Respiratory Medicine
G Kim Prisk, Janelle M Fine, Trevor K Cooper, John B West
Extravehicular activity (EVA) during spaceflight involves a significant decompression stress. Previous studies have shown an increase in the inhomogeneity of ventilation-perfusion ratio (VA/Q) after some underwater dives, presumably through the embolic effects of venous gas microemboli in the lung. Ground-based chamber studies simulating EVA have shown that venous gas microemboli occur in a large percentage of the subjects undergoing decompression, despite the use of prebreathe protocols to reduce dissolved N(2) in the tissues...
December 2005: Journal of Applied Physiology
Tsutomu Suzuki, Kaku Yoshimi, Jun Ueki, Yoshinosuke Fukuchi
The diffusing capacity of the lung for carbon monoxide (DLco) is usually measured by the single breath method with a 10-second breath hold. With the introduction of rapid gas analyzers, an alternative method for measurement of DLco, the intrabreath method, has been developed. The intrabreath method does not depend upon length of time or other conditions during either breath holding or expiration. The aim of this study was to compare the single breath method and intrabreath method of DLco measurement. DLco measured by the intrabreath method (DLco IB) was compared with DLco measured by the single breath method (DLco SB) in 32 normal subjects, 88 patients with obstructive impairment and 39 patients with restrictive impairment...
June 2005: Nihon Kokyūki Gakkai Zasshi, the Journal of the Japanese Respiratory Society
Mackenzie Quantz, Steven Wilson, Charles Smith, Larry Stitt, Richard Novick, Dildar Ahmad
BACKGROUND: Pulmonary function testing is an integral part of evaluating patients who are being considered for cardiac transplantation. The accurate measurement of diffusing capacity (DLCO) and alveolar volume (VA) is dependent on a 10-s breath-holding maneuver that may be difficult for patients with congestive heart failure to perform. The intrabreath (IB) technique is not dependent on a breath-holding maneuver and may provide more accurate pulmonary function testing results in chronically debilitated patients...
November 2003: Chest
G Kim Prisk, Harold J B Guy, John B West, James W Reed
The analysis of the gas in a single expirate has long been used to estimate the degree of ventilation-perfusion (Va/Q) inequality in the lung. To further validate this estimate, we examined three measures of Va/Q inhomogeneity calculated from a single full exhalation in nine anesthetized mongrel dogs under control conditions and after exposure to aerosolized methacholine. These measurements were then compared with arterial blood gases and with measurements of Va/Q inhomogeneity obtained using the multiple inert gas elimination technique...
March 2003: Journal of Applied Physiology
Yuh-Chin T Huang, Sharon R O'Brien, Neil R MacIntyre
BACKGROUND: Traditional approaches to measuring the diffusing capacity of the lung for carbon monoxide (DLCO) treat the lung as a single, well-mixed compartment and produce a single value for DLCO to represent an average diffusing capacity of the lung (DL). Because DL distribution in the lung is inhomogeneous, and changes in the DL in diseased lungs may be regional, measuring regional DL, especially during exercise, may be more sensitive in detecting pulmonary vascular diseases. OBJECTIVES: To characterize regional changes in DL in healthy individuals from rest to exercise, and to provide normal references for future studies in pulmonary vascular disorders...
July 2002: Chest
T Abe, T Yamada, T Tomita, P A Easton
In humans during stimulated ventilation, substantial abdominal muscle activity extends into the following inspiration as postexpiratory expiratory activity (PEEA) and commences again during late inspiration as preexpiratory expiratory activity (PREA). We hypothesized that the timing of PEEA and PREA would be changed systematically by posture. Fine-wire electrodes were inserted into the rectus abdominis, external oblique, internal oblique, and transversus abdominis in nine awake subjects. Airflow, end-tidal CO2, and moving average electromyogram (EMG) signals were recorded during resting and CO2-stimulated ventilation in both supine and standing postures...
June 1999: Journal of Applied Physiology
S H Mitchell, W G Teague
School-age children who survive bronchopulmonary dysplasia (BPD) may have a permanent reduction in alveolar surface area that could limit gas transfer both at rest and during exercise. To test this hypothesis, 10 survivors of BPD, 10 children born prematurely without BPD, and 10 healthy children born at term, 6 to 9 yr of age, underwent treadmill exercise studies. During a three-phase protocol we measured intrabreath acetylene (C2H2) and carbon monoxide (CO) transfer, pulmonary function, and SaO2. Both at rest and during exercise, C2H2 transfer corrected for body surface area was lower in survivors of BPD than it was in children born prematurely without BPD or children born at term...
May 1998: American Journal of Respiratory and Critical Care Medicine
G K Prisk, A R Elliott, H J Guy, J M Kosonen, J B West
We measured resting pulmonary gas exchange in eight subjects exposed to 9 or 14 days of microgravity (microG) during two Spacelab flights. Compared with preflight standing measurements, microG resulted in a significant reduction in tidal volume (15%) but an increase in respiratory frequency (9%). The increased frequency was caused chiefly by a reduction in expiratory time (10%), with a smaller decrease in inspiratory time (4%). Anatomic dead space (VDa) in microG was between preflight standing and supine values, consistent with the known changes in functional residual capacity...
October 1995: Journal of Applied Physiology
P A Easton, J W Fitting, R Arnoux, A Guerraty, A E Grassino
If costal and crural diaphragm segments can perform as separate muscles, then CO2-stimulated ventilation may elicit differential segmental function. We studied diaphragm segmental length, shortening, and electromyogram (EMG) activity in 10 awake dogs chronically implanted with sonomicrometer transducers and EMG electrodes. During CO2 rebreathing, segmental shortening and EMG activity per whole tidal breath progressively increased, but segmental responses could not be differentiated at any level of CO2. With increasing CO2, resting end-expiratory length of both diaphragm segments increased...
March 1993: Journal of Applied Physiology
D J Cotton, M B Prabhu, J T Mink, B L Graham
In normal seated subjects we increased single-breath ventilation inhomogeneity by changing both the preinspiratory lung volume and breath-hold time and examined the ensuing effects on two different techniques of measuring the diffusing capacity of the lung for carbon monoxide (DLCO). We measured the mean single-breath DLCO using the three-equation method (DLCOSB-3EQ) and also measured DLCO over discrete intervals during exhalation by the "intrabreath" method (DLCOexhaled). We assessed the distribution of ventilation using the normalized phase III slope for helium (SN)...
August 1993: Journal of Applied Physiology
P A Easton, T Abe, R N Young, J Smith, A Guerraty, A E Grassino
During natural panting for thermal regulation, the pattern of activation of the major respiratory muscles, including costal and crural diaphragm segments, is not known. We measured diaphragm segmental length, shortening, and electromyographic (EMG) activity in five chronically implanted canines awake and breathing spontaneously at rest and during a mild dry heat stress. During panting, minute ventilation increased fourfold from 5.07 l/min and respiratory rate increased from 16.9 to 192.8 breaths/min or 3.2 Hz...
October 1994: Journal of Applied Physiology
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"