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Volume Control (volume + control)

Distribution by Scientific Domains

Medical Sciences	50%
Life Sciences	50%

Selected Abstracts

A Single Ventilator for Multiple Simulated Patients to Meet Disaster Surge

ACADEMIC EMERGENCY MEDICINE, Issue 11 2006
Greg Neyman MD
Objectives To determine if a ventilator available in an emergency department could quickly be modified to provide ventilation for four adults simultaneously. Methods Using lung simulators, readily available plastic tubing, and ventilators (840 Series Ventilator; Puritan-Bennett), human lung simulators were added in parallel until the ventilator was ventilating the equivalent of four adults. Data collected included peak pressure, positive end-expiratory pressure, total tidal volume, and total minute ventilation. Any obvious asymmetry in the delivery of gas to the lung simulators was also documented. The ventilator was run for almost 12 consecutive hours (5.5 hours of pressure control and more than six hours of volume control). Results Using readily available plastic tubing set up to minimize dead space volume, the four lung simulators were easily ventilated for 12 hours using one ventilator. In pressure control (set at 25 mm H2O), the mean tidal volume was 1,884 mL (approximately 471 mL/lung simulator) with an average minute ventilation of 30.2 L/min (or 7.5 L/min/lung simulator). In volume control (set at 2 L), the mean peak pressure was 28 cm H2O and the minute ventilation was 32.5 L/min total (8.1 L/min/lung simulator). Conclusions A single ventilator may be quickly modified to ventilate four simulated adults for a limited time. The volumes delivered in this simulation should be able to sustain four 70-kg individuals. While further study is necessary, this pilot study suggests significant potential for the expanded use of a single ventilator during cases of disaster surge involving multiple casualties with respiratory failure. [source]

Fluid control in elderly patients with nocturia

INTERNATIONAL JOURNAL OF UROLOGY, Issue 3 2009
Osamu Natsume
Objectives: To investigate the pathophysiology of nocturnal polyuria associated with aging. Methods: Fifty patients (mean age 67.7 years, range 50,87) with nocturia were recruited for this prospective study. Patients were classified into nocturnal polyuria (NP) and non-nocturnal polyuria (non-NP) groups based on records of their frequency-volume charts. A hypertonic saline infusion test was carried out to evaluate individual osmotic and volume control. Results: In the NP group, there was a significantly increased nocturnal diuretic rate compared with the daytime diuretic rate. In the non-NP group, there was a significantly decreased nocturnal diuretic rate compared with the daytime rate. There was also a positive correlation between systolic blood pressure and nocturnal diuretic rate, and a negative correlation between systolic blood pressure and daytime diuretic rate in those with NP, but no correlation in those without NP. Thus, a close relationship between diuretic rates and systolic blood pressure was seen in NP patients. Moreover, a slight overall shift upward from the physiological range of plasma osmolality relative to arginine vasopressin after hypertonic saline loading was seen in those with NP compared with those without. An altered circadian rhythm was also seen in diurnal plasma arginine vasopressin levels in patients with and without NP. Conclusions: Patients with nocturnal polyuria are likely to have a more hypervolemic or vasoconstrictive condition. It is considered that non-osmotic control takes on a greater meaning in patients with nocturnal polyuria, though osmotic control contributes less to diuresis within the physiological plasma osmolality range with aging. [source]

Nitrosative stress induced cytotoxicity in Giardia intestinalis

JOURNAL OF APPLIED MICROBIOLOGY, Issue 3 2003
D. Lloyd
Abstract Aims: To investigate the antigiardial properties of the nitrosating agents: sodium nitrite, sodium nitroprusside and Roussin's black salt. Methods and Results: Use of confocal laser scanning microscopy and flow cytometry indicated permeabilization of the plasma membrane to the anionic fluorophore, DiBAC4(3) [bis(1,3-dibutylbarbituric acid) trimethine oxonol]. Loss of plasma membrane electrochemical potential was accompanied by loss of regulated cellular volume control. Changes in ultrastructure revealed by electron microscopy and capacity for oxygen consumption, were also consequences of nitrosative stress. Roussin's black salt (RBS), active at micromolar concentrations was the most potent of the three agents tested. Conclusions: These multitargeted cytotoxic agents affected plasma membrane functions, inhibited cellular functions in Giardia intestinalis and led to loss of viability. Significance and Impact of the Study: Nitrosative damage, as an antigiardial strategy, may have implications for development of chemotherapy along with suggesting natural host defence mechanisms. [source]

Control of Cell Volume in Skeletal Muscle

BIOLOGICAL REVIEWS, Issue 1 2009
Juliet A. Usher-Smith
Abstract Regulation of cell volume is a fundamental property of all animal cells and is of particular importance in skeletal muscle where exercise is associated with a wide range of cellular changes that would be expected to influence cell volume. These complex electrical, metabolic and osmotic changes, however, make rigorous study of the consequences of individual factors on muscle volume difficult despite their likely importance during exercise. Recent charge-difference modelling of cell volume distinguishes three major aspects to processes underlying cell volume control: (i) determination by intracellular impermeant solute; (ii) maintenance by metabolically dependent processes directly balancing passive solute and water fluxes that would otherwise cause cell swelling under the influence of intracellular membrane-impermeant solutes; and (iii) volume regulation often involving reversible short-term transmembrane solute transport processes correcting cell volumes towards their normal baselines in response to imposed discrete perturbations. This review covers, in turn, the main predictions from such quantitative analysis and the experimental consequences of comparable alterations in extracellular pH, lactate concentration, membrane potential and extracellular tonicity. The effects of such alterations in the extracellular environment in resting amphibian muscles are then used to reproduce the intracellular changes that occur in each case in exercising muscle. The relative contributions of these various factors to the control of cell volume in resting and exercising skeletal muscle are thus described. [source]