Time course of inhaled anaesthetic drug delivery using a new multifunctional closed-circuit anaesthesia ventilator. In vitro comparison with a classical anaesthesia machine †

Abstract

A combination of the fastest time course and lowest consumption of sevoflurane and desflurane was found when using the Zeus apparatus in AC uptake mode.

Assessing the clinical or pharmaco‐economical benefit of target controlled desflurane delivery in surgical patients using the Zeus® anaesthesia machine*

“…Our result that TCA did not reach a chosen target (i.e. the initial end tidal target of 4% desflurane) faster than MCA differs from the finding of Struys et al's [4] in vitro study, where TCA reached its target more than 1 min faster than did manual mode. However, Struys et al simulated volatile anaesthetic uptake by a continuous, fixed sampling of the breathed mixture of 0.2 l.min )1 and assumed a constant uptake over time and between patients, which is not true in clinical practice where uptake varies both in time (Fig.…”

“…Like both Struys et al [4] and Kennedy et al [9], we could not demonstrate a significant difference in the magnitude of the initial overshoot between both delivery modes. This result may be due to an insufficient statistical power or because MCA was especially carefully executed in our study.…”

“…All patients had a warming blanket to maintain a body temperature > 36°C throughout surgery. Desflurane consumption was recorded from the integrated Zeus Ò delivery system [4]. Anaesthesia was induced with thiopentone (5-8 mg.kg ), and a remifentanil effect-site TCI (Base Primea TM ; Fresenius, Brezins, France, Minto's pharmacokinetic model [5]) set at an initial target concentration of 5 ng.ml .…”

“…This Target Controlled Anaesthesia Ò (TCA), is expected to 1 Minimise the time required to achieve a desired endtidal anaesthetic concentration, 2 Reduce overshoot and fluctuations, 3 Reduce gas and vapour consumption and 4 Reduce the number of adjustments needed -all in a similar manner to target controlled infusion (TCI) for intravenous agents. These expectations have been confirmed in vitro: TCA achieved equilibration as fast as conventional manual delivery with a high FGF, but without overshoot, and markedly reduced volatile agents consumption [4]. However, TCA performance has not been assessed in a clinical setting.…”

Porównanie zużycia gazów anestetycznych oraz stabilności znieczulenia przy użyciu automatycznej i ręcznej kontroli przebiegu znieczulenia

“…In their study, the automated control module abruptly adjusted the desired flows, which increased the saturation time. Otherwise, the study by Struysa et al [10] revealed that the desired level of anaesthetic was achieved more rapidly in the group with automated measurements of EtAA. However, the study was performed with an in vitro model confined to the respiratory system, which did not consider the phase of anaesthetic redistribution.…”