March 14th, 2024
Production of Halothane Ceases: Implication for Diamedica Vaporisers?
The production and supply of Halothane is to cease, Halothane has been the principle agent in many Low and Middle Income Countries (LMICs) for a long time, due to its lower cost and its tolerance when providing a gaseous induction. However another agent is available that is suitable to use in the Halothane vaporiser, that agent is Isoflurane.
The Diamedica vaporisers labelled either ‘Halothane’ or ‘Halothane/Isoflurane’ are both suitable to use with Isoflurane. The reason that this may be possible is related to the very similar Saturated Vapour Pressures (SVPs) of Halothane and Isoflurane, this leads to a similar output, in percentage, from the same device.
Changing the agent and during use:
Before use with new agent
The vaporiser should be cleared of any remaining Halothane by running gases through it until all trace is removed.
During use
The percentage output with Isoflurane will be very similar but the MAC is different and it is about 1/3 less as potent, so a higher setting will be required.
Halothane MAC = 0.73
Isoflurane MAC = 1.1
In addition, Isoflurane is less tolerated as a gaseous induction agent, particularly with paediatric patients and an IV induction may be preferable.
The vaporiser agent label should identify the agent being used and any agent specific filler would need to be changed to avoid any confusion.
Diamedica (UK) Ltd has been uniquely manufacturing and supplying a dual agent vaporiser for many years. This vaporiser was specially designed to be able to utilise Halothane or Isoflurane without the need for any modification to the vaporiser. There were two reasons for this enhanced specification, the first was to reduce costs to the end users, allowing for either agent when one was not available. The second was for the situation that we now face, the loss of one of those agents.
Unfortunately, because of the very different SVP with Sevoflurane this agent requires a separate specific vaporiser. Diamedica (UK) Ltd do produce a Sevoflurane vaporiser and have been supplying that as an option for several years; either with a single vaporiser anaesthesia machine or on a machine with two vaporisers.
An anaesthetic machine equipped with both an Isoflurane and a Sevoflurane vaporiser enables a smooth and rapid gaseous induction using Sevoflurane, followed by cost-effective maintenance with Isoflurane.
You can find more details on our vaporiser here. For support relating to your Diamedica vaporiser please email here.