Articles: closed-circuit-anesthesia.
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Comparative Study
Performance of four carbon dioxide absorbents in experimental and clinical settings.
To evaluate the performance of four kinds of carbon dioxide (CO(2)) absorbents (Medisorb GE Healthcare, Amsorb Plus Armstrong Medical, YabashiLime Yabashi Industries, and Sodasorb LF Grace Performance Chemicals), we measured their dust production, acceptability of colour indicator, and CO(2) absorption capacity in in vitro experimental settings and the concentration of compound A in an inspired anaesthetic circuit during in vivo clinical practice. In vitro, the order of the dust amount was Sodasorb LF > Medisorb > Amsorb Plus = YabashiLime both before and after shaking. ⋯ In vivo, compound A (1.0% inspired sevoflurane) was detected only when using Medisorb. While Medisorb has the best ability to absorb CO(2), it alone produces compound A.
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Acta Anaesthesiol Belg · Jan 2009
Comparative Study Clinical TrialDesflurane consumption with the Zeus during automated closed circuit versus low flow anesthesia.
During automated closed-circuit anesthesia (CCA), the Zeus (Dräger, Lübeck, Germany) uses a high initial fresh gas flow (FGF) to rapidly attain the desired agent and carrier gas concentrations, resulting in a desflurane consumption well above patient uptake. Because both FGF and carrier gas composition can affect consumption, we determined the Zeus' agent consumption with automated CCA and with automated low flow anesthesia (LFA) (= maintenance FGF of 0.7 L min(-1)) with 3 different carrier gases. ⋯ After 50 min, desflurane consumption with automated CCA is lower than with automated LFA. However, initial agent consumption is complex, and N2O in particular may increase initial desflurane consumption (though ultimately resulting in lower desflurane usage because of its MAC sparing effect) because initial FGF is increased to rapidly reach the target concentrations. Differences in desflurane consumption only become apparent after FGF has stabilized to the target FGF.
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Anesthesia and analgesia · Oct 2008
Randomized Controlled TrialThe accuracy and clinical feasibility of a new bayesian-based closed-loop control system for propofol administration using the bispectral index as a controlled variable.
Closed-loop control of the hypnotic component of anesthesia has been proposed in an attempt to optimize drug delivery. Here, we introduce a newly developed Bayesian-based, patient-individualized, model-based, adaptive control method for bispectral index (BIS) guided propofol infusion into clinical practice and compare its accuracy and clinical feasibility under direct observation of an anesthesiologist versus BIS guided, effect compartment controlled propofol administration titrated by the anesthesiologist during ambulatory gynecological procedures. ⋯ The Bayesian-based closed-loop control system for propofol administration using the BIS as a controlled variable performed accurate during anesthesia for ambulatory gynecological procedures. This control system is clinical feasibility and can be further validated in clinical practice.
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Anaesth Intensive Care · Sep 2008
Evaluation of an Oxford Miniature Vaporizer placed in-circuit during the maintenance phase of low-flow anaesthesia.
The aim of the study was to assess Oxford Miniature Vaporizer output when mounted in-circuit during the maintenance phase of anaesthesia, using isoflurane, controlled ventilation and a fresh gas flow rate less than 1 l/min. Twenty patients of ASA Physical Status I and II were recruited from routine general surgical lists. All patients were paralysed and ventilated. ⋯ At a dial setting of 0.5, the Oxford Miniature Vaporizer produced a steady end-tidal isoflurane of 0.63% (95% confidence interval 0.60 to 0.66). However, when the dial was turned to 1.0 the output was almost always excessive and had to be reduced. These findings indicate that a stable, predictable and clinically useful output can be achieved when the Oxford Miniature Vaporizer is positioned in-circuit using low-flow and controlled ventilation.
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Randomized Controlled Trial
Pre-oxygenation in pregnancy: the effect of fresh gas flow rates within a circle breathing system.
We have investigated the effect of oxygen flow rate on pre-oxygenation in pregnant patients at term using a circle system. Twenty patients presenting for elective Caesarean section maintained tidal volume breathing through a standard circle system for 3 min. Subjects were pre-oxygenated using oxygen flow rates of 5 l.min(-1), 10 l.min(-1) and 15 l.min(-1) presented in random order. ⋯ Entrainment of air occurred in 22% of pre-oxygenation sessions. Oxygen flow rates of 10 l.min(-1) or above provide optimal pre-oxygenation using a circle system in term parturients. In our study, entrainment of air occurred in a surprisingly high percentage of cases.