Low-flow anaesthesia – underused mode towards “sustainable anaesthesia”

Abstract

Any technique that employs a fresh gas flow that is less than the alveolar ventilation can be classified as low-flow anaesthesia. The complexities involved in the calculation of uptake of anaesthetic agents during the closed-circuit anaesthesia made this technique less popular. However, the awareness of the dangers of theatre pollution with trace amounts of the anaesthetic agents and the prohibitively high cost of the new inhalational agents, have helped in the rediscovery of low-flow anaesthesia. Moreover, the time has arrived for each of us, the practicing anaesthesiologists, to move towards the practice of low-flow anaesthesia, to achieve lesser theatre and environmental pollution and also to make anaesthesia more economical. The article also reviews low-flow anaesthesia (LFA) in paediatrics, recent advances such as automated LFA and updates on currently undergoing research to retrieve and reuse anaesthetic agents.

A randomised prospective comparison of equilibration point and changing gas composition during low-flow anaesthesia with sevoflurane vs desflurane

“…[9] In LFA, N 2 O usually shows an increasing trend of its concentration while O 2 shows a decreasing trend because the body consumes O 2 and not N 2 O. [1] In our study, O 2 was kept at 50% after shifting to LFA. A higher concentration of O 2 compared with conventional technique is recommended in LFA to prevent undesirable fall in FiO 2 especially, while using N 2 O.…”

“…One of the techniques includes giving high FGF of 6–10 L/min initially for about 3–6 min to reach a high level of alveolar gas concentration to achieve surgical anaesthesia (loading) which is followed by a reduction in total gas flows during maintenance. [1] An alternative technique is using low FGF from the beginning with very high vaporiser setting to achieve target alveolar concentration. [2] Haemodynamic stability during this phase may be a challenge.…”

The Effect of Sevoflurane Low Flow Anesthesia on Preserving Patient Core Temperature 

“…Low ow anesthesia reduces the fresh gas ow (FGF) entering the anesthesia circuit and saves on volatile agent used, which saves on inhaler gas and prevents unnecessary waste gas emissions into the atmosphere. Ventilation applied with fresh gas addition less than alveolar ventilation can be called low ow anesthesia [1]. Repeated use of unused volatile anesthetic in expiratory gas saves on use without changing the level of anesthesia in patients [2].…”

Desflurane with Isoflurane under low flow anaesthesia: A prospective randomized clinical comparative trial

“…Various techniques and endpoints are in use to shift from high-flow to low-flow anaesthesia. One of the techniques includes giving high FGF of 6-10 L/min initially for about 3-6 min to reach a high level of alveolar gas concentration to achieve surgical anaesthesia (loading) which is followed by a reduction in total gas flows during maintenance [1] . An alternative technique is using low FGF from the beginning with very high vaporiser setting to achieve target alveolar concentration [2] .…”