Search results for "Dead space"
showing 8 items of 8 documents
Alveolar Gas Mixing in Chronic Pulmonary Hyperinflation
1991
It is well known that in chronic pulmonary hyperinflation defects in intrapulmo-nary gas mixing and in V/Q ratio are likely to occur.
Differential contribution of dead space ventilation and low arterial pCO2 to exercise hyperpnea in patients with chronic heart failure secondary to i…
2003
In chronic heart failure (CHF), the abnormally large ventilatory response to exercise (VE/VCO(2) slope) has 2 conceptual elements: the requirement of restraining arterial partial pressure of carbon dioxide (pCO(2)) from increasing (because of an increased ratio between increased physiologic dead space and tidal volume [VD/VT]) and the depression of arterial pCO(2) by further increased ventilation, which necessarily implies an important non-carbon dioxide stimulus to ventilation. We aimed to assess the contribution of these 2 factors in determining the elevated VE/VCO(2) slope in CHF. Thirty patients with CHF underwent cardiopulmonary exercise testing (age 65 +/- 11 years, left ventricular e…
Measurement of phase I volume breath by breath in spontaneously breathing guinea pigs.
1990
A new method to determine phase I volume in tracheotomized spontaneously breathing guinea pigs is presented. Measurements were performed in three animals weighing 567-896 g. In simultaneous tracings of tidal volume (VT) and expiratory profiles of endogenous gases (PO2 or PCO2), the phase I volume of each breath was determined graphically as the volume expired up to the end of phase I of the expirogram. The mean phase I volume of different animals ranged from 0.29 to 0.43 ml with an arithmetic dispersion between 0.014 and 0.021 ml. Spontaneous sighs sometimes with doubling of the VT caused a significant rise of phase I volume up to 50% of the normal values. The linear regression curve was c…
Über die klinische Anwendbarkeit der Methode des Totluftplateaus zur Messung des anatomischen Totraumes
1976
Die neue Methode des sogenannten Totluftplateaus lies von der Konzeption her erwarten, das sie auch bei Patienten mit gestorter Lungenfunktion richtige Werte fur das anatomische Totraumvolumen liefert. Es wird daher die neue Methode intraindividuell mit der bekannten Methode nach Bohr und der Totraumbestimmung mit Hilfe der graphischen Auswertung nach Fowler (O2 als Mesgas) an 6 mannlichen Patienten mit unterschiedlichen Lungenerkrankungen verglichen. Es zeigt sich, das nur die neue Methode den anatomischen Totraum richtig, d. h. unvergrosert, mist. Die gemessenen Volumina zeigen zudem die bei Lungengesunden vorhandene Korrelation zur Korpergrose. Es wird die Schwierigkeit der Definierung d…
Eine neue Methode zur Messung des anatomischen Totraumes mit Hilfe des Totluft-Plateaus
1975
Im Exspirationsrohr eines Atemventils, welches sich nahe am Mund des Probanden befindet werden gleichzeitig O2-Partialdruck mit einer O2-Elektrode und exspiriertes Volumen mit einem Pneumotachographen gemessen. Die PO2-Anzeige hat eine 90%-Einstellzeit von 40 ms. Wahrend der Totluft-Bolus die O2-Elektrode passiert, wird das sogenannte Totluft-Plateau gemessen. Das bis zum Ende des (korrigierten) Totluft-Plateaus exspirierte Volumen entspricht dem Totraumvolumen. Das Totluft-Plateau wird durch Stromungs- und Diffusionsverbreiterung im Respirationstrakt verkurzt. Die Verbreiterung wird im Exspirationsrohr simuliert, sowie mit einer zweiten O2-Elektrode gemessen und als Korrektur berucksichtig…
Theoretical Analysis of Factors Influencing Recovery of Ventilation Distributions from Inert Gas Washout Data
1990
For the quantitative analysis of intraregional ventilation inhomogeneities, one classically applies the inert gas washout method [7,24] in which an inert gas of negligible solubility in blood and tissue is washed into the lungs. After washin is complete, the inspiratory inert gas fraction is set to a smaller value and the time course of the mixed endexpiratory inert gas fraction during the subsequent inert gas washout is recorded. The determinants of this time course are: The endexpiratory alveolar volume at the instant of change in inspiratory inert gas fraction, the anatomical dead space, the gas exchange ratio, the respiratory frequency, the in- and expiratory tidal volumes, and the inho…
Hipertensión endocraneal asociada a la sedación con sevoflurano mediante el dispositivo AnaConDa®en un paciente con traumatismo craneoencefálico seve…
2013
Sedation in neurocritical patients remains a challenge as there is no drug that meets all the requirements. Since the appearance of the AnaConDa® device, and according to the latest recommendations, sevoflurane has become an alternative for patients with brain injury. The use of AnaConDa® produces an increase in the anatomical dead space that leads to a decrease in alveolar ventilation. If the decrease in the alveolar ventilation is not offset by an increase in minute volume, there will be an increase in PaCO2. We report the case of a patient with severe traumatic brain injury who suffered an increase in intracranial pressure as a result of increased PaCO2 after starting sedation with the A…
Ein Mikro-Atemstromventil für spontan atmende narkotisierte Kleintiere - A Respiratory Micro-Valve for Spontaneously Breathing Anaesthetized Small An…
1994
For the accurate functional analysis of the gas exchange in the lungs or evaluation of artificial oxygen carriers in spontaneously breathing anaesthetized small animals, we developed a new respiratory micro-valve. The body of the valve is made of aluminium, and the flaps are made of silicone rubber. The maximum flow rate in a rat measured with a pneumotachograph and the micro-valve was an average of 19.9 ml/s during inspiration, and 17.8 ml/s during expiration. The pressure measured in the tracheal tube was -0.85 during inspiration, and +0.39 cm H2O during expiration; the end-expiratory pressure in the tube was zero. In two experiments with anaesthetised rats lasting 4-5 hours, ventilation,…