Xenon measurement in breathing systems: a comparison of ultrasonic and thermal conductivity methods

King, R.; Bretland, M.; Wilkes, A. R.; Dingley, John

doi:10.1111/j.1365-2044.2005.04379.x

Cited by 12 publications

(8 citation statements)

References 29 publications

(31 reference statements)

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“…An alternative, more accurate method can be based on the speed of sound which is far lower in xenon than in oxygen and nitrogen. 9 Xenon does not impair paramagnetic and galvanic measurements or infrared analysis of oxygen, carbon dioxide and volatile concentrations. 10 Because limitation of gas expenditure has a high priority when using xenon, a closed circuit anesthesia machine with electronically controlled gas dosage is the best technical solution (eg, the former PhysioFlex, built by Draeger, Germany).…”

Section: Xenon Techniquesmentioning

confidence: 99%

Xenon-based anesthesia: theory and practice

Baumert¹

2009

OAS

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Xenon has been in use as an anesthetic for more than 50 years. Although it exhibits some of the properties of an ideal anesthetic, the technical complexity of xenon equipment and the high cost of the gas have prevented widespread use of xenon anesthesia. The main beneficial features of xenon anesthesia are fast induction and emergence because of low solubility in blood and tissues, along with remarkably stable hemodynamics even in patients with impaired cardiac function. Xenon has proven to be a safe and well-tolerated anesthetic in clinical trials. The primary mechanism by which xenon produces anesthesia-antagonism at the neuronal N-methyl-D-aspartate receptor-and the absence of vasodilating effects distinguish xenon from most other inhaled and intravenous anesthetics. In addition, xenon can protect cells from ischemia-reperfusion damage. This effect was demonstrated in myocardium and neuronal cells as well. Myocardial and cerebral infarction sizes after ischemia can be reduced substantially by xenon, even when administered after the initial insult. Because of its high cost, routine xenon anesthesia may be justified only if it is associated with fewer perioperative complications, shorter duration of hospital stay or significant reduction of perioperative risk. Clinical studies to identify a specific group of patients in which these requirements are met are still lacking.

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Section: Xenon Techniquesmentioning

confidence: 99%

Xenon-based anesthesia: theory and practice

Baumert¹

2009

OAS

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“…The measurement error of the thermal conductivity for xenon averages about 5% when compared with laser refractometry. 18 The use of low flow anaesthesia enhances this error by causing a larger accumulation of humidity in the tubing, which can be avoided by water traps and a small chamber of silica-gel desiccant placed in the sampling line. 18 The correct measurement of the xenon concentration is a prerequisite to judgements regarding the accumulation of strange gas, which often serves as a trigger for flushing the system, a procedure that will then dramatically increase the total xenon consumption.…”

Section: Discussionmentioning

confidence: 99%

“…Although precise xenon sensors are not available, the fresh gas flow of xenon and oxygen should be strictly controlled by the system volume and the oxygen concentration to avoid hypoxic gas mixtures and low xenon concentrations. 18 Automated protocols using the expiratory oxygen concentration as the control value are suitable for preventing low inspiratory oxygen concentrations and thus increasing safety.…”

Section: Discussionmentioning

confidence: 99%

A practical rule for optimal flows for xenon anaesthesia in a semi-closed anaesthesia circuit

Röhl

Goetzenich

Rossaint

et al. 2010

European Journal of Anaesthesiology

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The current study showed that, by optimization of the electronic regulation of the wash-in procedure for xenon anaesthesia, the consumption of the valuable gas can be reduced by up to 75% in a semi-closed circuit. The additional maintenance of anaesthesia under low flow conditions by coupling the xenon flow to the oxygen consumption is the most effective way to technically reduce the amount of xenon needed for anaesthesia.

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“…2,3 Therefore measurement of Xe (%): O2 (%) mixtures usually requires two different devices: a thermal conductivity meter (TCM) and a fuel cell respectively. 4,5 Anesthetic gas flow is typically measured using the pneumotachograph principle; however the high density of Xe renders these devices inaccurate. Ultrasonic Flow Meters (UFM) are unaffected by gas density and provide a low cost, robust, sterilizable alternative.…”

Section: Discussionmentioning

confidence: 99%

Real-Time Measurement of Xenon Concentration in a Binary Gas Mixture Using a Modified Ultrasonic Time-of-Flight Anesthesia Gas Flowmeter: A Technical Feasibility Study

Williams

Hallewell

Chakkarapani

et al. 2019

Anesthesia &Amp; Analgesia

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BACKGROUND: Xenon (Xe) is an anesthetic gas licensed for use in some countries. Fractional concentrations (%) of gases in a Xe:oxygen (O2) mixture are typically measured using a thermal conductivity meter and fuel cell, respectively. Speed of sound in such a binary gas mixture is related to fractional concentration, temperature, pressure, and molar masses of the component gases. We therefore performed a study to assess the feasibility of developing a novel single sterilizable device that uses ultrasound time-of-flight to measure both real-time flowmetry and fractional gas concentration of Xe in O2. METHODS: For the purposes of the feasibility study, we adapted an ultrasonic time-of-flight flowmeter from a conventional anesthetic machine to additionally measure real-time fractional concentration of Xe in O2. A total of 5095 readings of Xe % were taken in the range 5%–95%, and compared with simultaneous measurements from the gold standard of a commercially available thermal conductivity Xe analyzer. RESULTS: Ultrasonic measurements of Xe (%) showed agreement with thermal conductivity meter measurements, but there was marked discontinuity in the middle of the measurement range. Bland-Altman analysis (95% confidence interval in parentheses) yielded: mean difference (bias) 3.1% (2.9%–3.2%); lower 95% limit of agreement −4.6% (−4.8% to −4.4%); and upper 95% limit of agreement 10.8% (10.5%–11.0%). CONCLUSIONS: The adapted ultrasonic flowmeter estimated Xe (%), but the level of accuracy is insufficient for clinical use. With further work, it may be possible to develop a device to perform both flowmetry and binary gas concentration measurement to a clinically acceptable degree of accuracy.

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Xenon measurement in breathing systems: a comparison of ultrasonic and thermal conductivity methods

Cited by 12 publications

References 29 publications

Xenon-based anesthesia: theory and practice

Xenon-based anesthesia: theory and practice

A practical rule for optimal flows for xenon anaesthesia in a semi-closed anaesthesia circuit

Real-Time Measurement of Xenon Concentration in a Binary Gas Mixture Using a Modified Ultrasonic Time-of-Flight Anesthesia Gas Flowmeter: A Technical Feasibility Study

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