Determination of anaesthetic agent concentration by refractometry

174

SummaryThe 'Diprifusor' target controlled infusion system has been developed as a standardised infusion system for the administration of propofol by target controlled infusion. A preferred set of pharmacokinetic parameters for propofol was selected using computer simulation of a known infusion scheme with pharmacokinetic parameters described in published literature. The selected model was included in a 'Diprifusor' module that was interfaced with, and later incorporated into, a computer-compatible infusion pump. Clinical trials with such systems led to guidance on appropriate target concentrations for the administration of propofol by 'Diprifusor' target controlled infusion for inclusion in drug prescribing information. Standardisation of the delivery performance (Ϯ 5%) of commercial systems has been achieved with a laboratory performance specification. Clinical studies indicate that the actual blood concentrations achieved were about 16% greater than the calculated values displayed by the system. In an individual patient, titration of the target concentration is required in the same manner as an anaesthetic vapouriser is adjusted to obtain a specific pharmacodynamic effect.

mentioning

confidence: 70%

The development of ‘Diprifusor’: a TCI system for propofol

Glen

1998

174

“…The interlock between the vaporisers was removed and they were calibrated using the method described by Allison et al . [16]. Bispectral index (BIS) and spectral edge frequency (SEF) monitoring was conducted using BIS Aspect Medical Systems (Newton, MA, USA) (DSC‐XP) electroencephalographic (EEG) monitor.…”

Section: Methodsmentioning

confidence: 99%

A comparison of 8% and 12% sevoflurane for inhalation induction in adults

Goodwin¹,

Campbell²,

Hall³

et al. 2004

SummarySevoflurane is a non-pungent volatile anaesthetic agent with a low blood-gas solubility coefficient. It has been studied in concentrations of up to 8% for induction of anaesthesia. Previous work has suggested that there may be a ceiling effect with increasing concentration of sevoflurane above 6%, but there are no published studies using 12% sevoflurane. This study compared 8 and 12% sevoflurane to induce anaesthesia in adults. Sevoflurane was administered using two adapted datum vaporisers with the interlock removed. Induction with 12% sevoflurane compared to 8% sevoflurane produced a significant decrease in the time to achieve central pupils, corresponding to surgical anaesthesia and the third part of Guedel's stage 3 of anaesthesia (mean time (SD) 201 s (81) and 247 s (39), respectively, p < 0.05). Twelve-percent sevoflurane produced a similar stable cardiovascular profile to 8% sevoflurane, and there was no increase in respiratory complications.

“…We stored 30 s of data for subsequent analysis for each challenge. The vaporisers and monitor were calibrated using the method described by Allison et al [16]. The procedure was explained to each volunteer on each visit.…”

Section: Methodsmentioning

confidence: 99%

Adverse airway events during brief nasal inhalations of volatile anaesthetics: the effect of humidity and repeated exposure on incidence in volunteers preselected by response to desflurane*

Wilkes¹,

Raj²,

Hall

2003

SummaryTwelve volunteers known to have airways that responded adversely to 2.0 MAC desflurane were recruited. Each volunteer inhaled three single breaths of each of 0.5, 1.0 and 2.0 MAC of sevoflurane, halothane, isoflurane, desflurane and balance air, with breaths of air between, whilst breathing nasally through a face mask attached to one of three filters that provided three different levels of humidification. The incidence of any adverse airway events was recorded. The anaesthetic inhaled significantly affected the incidence of adverse airway events (p < 0.001), with the least to most irritant being sevoflurane, halothane, isoflurane and desflurane. Increasing the concentration of anaesthetic also significantly increased the incidence of adverse airway events (p < 0.001). The filter used, and hence the level of humidification, did not affect the incidence of adverse airway events (p ¼ 0.09), but repeated exposure caused a significant reduction in the incidence of adverse airway events (p < 0.001).