This CPD session is sponsored by Chanelle Pharma and is designed to provide an overview of the use of sevoflurane and isoflurane in general anaesthesia of dogs and cats. It explores the differences between these agents and factors to consider when selecting the type of gas. The presentation also explores MAC, anaesthetic maintenance, patient factors and monitoring. 

Dr Jonathan starts the webinar by explaining the different types of anaesthesia that exist and how, why and the benefit of using inhalation anaesthetics, as well as explaining their effect on patients. 

The most used inhalation anaesthetics are isoflurane and sevoflurane. One of the objectives of the webinar is to understand when to use which anaesthetic, which Dr Jonathan emphasises that it depends on several factors.    

The first being MAC, which is used to compare the potency of the anaesthetic vapour. Taking this into account, sevoflurane will need a higher anaesthetic vapour setting compared to isoflurane. 

Then we are faced with induction, maintenance and recovery speed. Sevoflurane reaches the equilibrium point faster than isoflurane, so it will enter and leave the body faster when the flow enters or stops, making both induction and recovery faster. 

Regarding cost, sevoflurane costs more and higher volume is needed, although the webinar also covers generic sevoflurane which makes its use more affordable. 

Adverse effects that may be observed in patients when using inhalation anaesthetics include: 

  • Respiratory Depression 
  • Depression of central nervous system 
  • Hypotension 
  • Muscle relaxation 
  • Vasodilatation 
  • Myocardial depression 
  • Depression of body temperature regulating centres 
  • GI effects 
  • Malignant hypothermia: occurs rarely   

All these effects are to be expected when using a CNS depressant anaesthetic, but it is when too much of this anaesthetic is used that they are adverse. 

Another factor that we must consider when choosing an anaesthetic are the patient factors. Dr Jonathan gives a list of factors that we can observe in our patients and explains that if any of our patients have any of the factors mentioned in the webinar, we should decrease the dose of the anaesthetic agent, as the agent will be more potent to that patient. 

The webinar continues with how patient factors affect the MAC and anaesthetic procedures, where several cases are shown, with their clinical history and an explanation from Dr Jonathan on their effects on the MAC. The webinar becomes a very dynamic and interesting webinar. 

Controlling the depth of anaesthesia is a subject that Dr Moore touches on. We are given a list of factors with explanations, and warnings of what to be aware of. The ones that need to be constantly monitored are also mentioned and how we can adapt to the different changes we have to make according to our patient. 

If you are interested in learning and understanding more about inhalation anaesthesia, this is the perfect webinar for you, it gives many resources for further learning and is remarkably interesting.