Closed-Circuit Halothane and Enflurane Using an in-Circle Goldman Vaporizer

Abstract

A closed-circle absorber system incorporating an in-circle Goldman vaporizer was used to administer halothane or enflurane in oxygen to adult patients. The attained inspired and end-tidal concentrations of volatile agent after a period of stabilization at each vaporizer setting were measured by mass spectrometry. During spontaneous respiration under halothane the ranges of inspired concentrations at settings 1, 11/2 and 2 were respectively 0.5-0.9%, 1.4-2.4% and 3.3-4.5%. corresponding inspired enflurane concentrations at the same settings were 0.8-1.4%, 1.9-2.8% and 3.7-5.0%. IPPV to 5% end-tidal carbon dioxide, although increasing the inspired concentrations slightly, produced considerable increases in end-tidal concentrations. Minimal pre-oxygenation was used to assess the problem of nitrogen accumulation within the circuit. The maximum nitrogen concentration was 56%.

Uptake of isoflurane during prolonged clinical anaesthesia

“…There is no conventional fresh gas supply to this system, but some of the oxygen oscillating in the trunk is retained in the circle as oxygen there is consumed by the patient. 12 Liquid iso¯urane is injected directly from a glass syringe (GT-50, SGE Europe Ltd, Milton Keynes, UK) into an in-circle vaporizing chamber ( Fig. 1).…”

Delivery of sevoflurane to dogs using a Stephens anaesthetic machine

“…Differences in vaporizer output due to dog size are seen with non‐flow compensated in‐circle vaporizers where the gas flow is generated by the dogs’ respiration. Thus, their respiratory minute volume affects the concentration of anaesthetic agent in the breathing system (Cust ; Jordan & Bushman ; Brosnan et al. ; Laredo et al.…”

The Komesaroff anaesthetic machine for delivering sevoflurane to dogs

“…As a result of this, a self‐regulating system may become established when the patient breathes spontaneously: surgery performed under ‘light’ anaesthesia increases minute volume and so increases vaporizer output, ‘deepening’ anaesthesia. These systems have been described as self‐regulating (Jordan & Bushman 1981; White 1985).…”