Cost-effectiveness of Basal Flow Sevoflurane Anaesthesia Using the Komesaroff Vaporizer inside the Circle System

Abstract

After ethics committee approval, 51 consenting ASA physical status 1 or 2 adult patients were given basal flow sevoflurane anaesthesia using fresh gas flows of 150 to 300 ml.min-1 oxygen. A Komesaroff vaporizer was placed on the inspiratory limb of the circle system. Basal flows were introduced immediately following intravenous induction of anaesthesia. The vaporizer was set to deliver the maximum concentration until the inspired sevoflurane concentration (FSI) reached 3%. The dial was then adjusted to maintain the FSI at 3%. After every 60 minutes, the circuit was washed out with 100% oxygen at a flow rate of 10 l.min-1 for one minute. The FSI reached 3% after an average of 8.5 (3.8) [mean (SD)] minutes. The trends in FSI and the expired sevoflurane concentrations were significantly different (P<0.05) between the mechanically ventilated patients (n=21) and the spontaneously ventilating patients (n=30) and demonstrated a more gradual build-up in the former group. The consumption of sevoflurane was found to be 9.2 (2.8) ml.h-1. This represented a 52.5% cost saving over the clinical application of the Mapleson's ideal fresh gas flow sequence for low-flow anaesthesia.

Compound A, formaldehyde and methanol concentrations during low‐flow sevoflurane anaesthesia: comparison of three carbon dioxide absorbers

“…In addition to economy, CO 2 absorption during low‐flow anaesthesia provides excellent conditioning of the humidification of the inspiratory gas with regard to heat and moisture and allows for a significant decrease in operating room pollution. Nevertheless, little change has taken place in the use of soda lime or its variants as CO 2 absorbers since their introduction (5–7).…”

Population pharmacokinetics of sevoflurane in conjunction with the AnaConDa®: toward target‐controlled infusion of volatiles into the breathing system

“…Before a steady state, agent saving may be minimally higher. The sevoflurane consumption with AnaConDa s was also low in comparison with systems with a vaporizer within the circle system (17,18).…”

“…Based on existing empirical recommendations, the initial infusion rate of liquid sevoflurane into the AnaConDa s was 40-60 ml/h until sevoflurane could be detected in the breathing system, which took approximately 30 s. The infusion rate was then reduced to about half the initial for approximately 1 min, and thereafter it was halved again. Later, the infusion rate was changed to yield 0.5-1.0% stepwise alterations of end-tidal concentrations, unless anesthesia was deemed to be unsatisfactory [440% change of the pre-operative systolic blood pressure, or 4160, or o80 mmHg, or an AAI index lower than 10, or exceeding 30 (recommended range: [15][16][17][18][19][20][21][22][23][24][25]]. The different concentration steps were maintained for at least 15 min.…”

Low Flows Revisited

“…This issue of the Journal contains an article highlighting another simple technique to provide low-flow anaesthesia 1 . Since the symposium issue in August 1994 2 , the Journal has published only a few articles on low flow or closed-circuit anaesthesia [3][4][5][6][7] , suggesting that this form of general anaesthesia is still not very popular in this region, despite its well recognised financial and environmental advantages 8,9 .…”