Anaesthetics are a routine part of the day at the Ark Veterinary Centre. We regularly administer anaesthetics to everything from small kittens to large dogs, with occasional small furries and the odd reptile or bird. While it is part of our normal day, we appreciate that being told your animal needs a procedure involving a general anaesthetic is scarey for every owner.
There is always a small risk with any animal (or human) being given a general anaesthetic. We do everything we can to minimise this risk. A full pre-anaesthetic health check, often involving blood tests for the older animal, use of the most up to date anaesthetics and pain relief, and close monitoring throughout the anaesthetic help to ensure safe and speedy recovery.
From the time your pet goes to sleep until they wake up many parameters in their body are constantly monitored and recorded on a chart. The values entered on this chart help us to decide if the depth of anaesthesia is correct for your pet and for the procedure that they require. Some procedures (e.g. x-rays or minor lump removals) do not require as deep an anaesthetic as others such as fixing a broken leg. Every animal is an individual and their reaction to anaesthetic will also vary. Their anaesthetic chart helps us decide on the correct level of anaesthetic for them.
A pulse oximeter is a machine with a small probe which is placed on your pet’s ear, toe or tongue (you may have had on on your finger at some point). It measures the amount of oxygen in the red blood cells that circulate in the blood. It is essential that the blood carries enough oxygen to the brain at all times, and this machine will give us an early warning if the levels start to fall, long before they reach a point that could be dangerous. This will allow us to make changes and help with ventilation until things settle.
The body is designed to regulate its blood pressure and keep it within a certain range. Staying within this range ensures that enough blood is delivered to the major organs (brain, kidneys, heart) to keep them functioning correctly. When an animal (or human) is under anaesthetic, some of this fine tuning is lost and if they go too deep their blood pressure will drop too low. If this happens, not enough blood will get to the important organs and damage will occur. During your pet’s anaesthetic, we continually monitor their blood pressure and perform any adjustments to the anaesthetic required, to ensure it stays within the range needed.
The ECG monitors the electrical activity in the heart and shows us if the heart is beating normally. It is particularly important in certain breeds of dog that are prone to abnormal heart rhythms, or certain procedures what may have an effect on the heart rhythm.
The capnograph measures the amount of carbon dioxide that the body is breathing out as well as the number of breaths per minute. It is crucial not only to know the respiration rate but also that the lungs are working well, bringing oxygen and anaesthetic gas into your pet’s body, and removing the waste gas (carbon dioxide) from their body.
Monitoring body temperature is a crucial part of anaesthetic monitoring. Once an animal (or human) is asleep their ability to prevent heat loss and generate extra heat (e.g. by shivering) is removed. If nothing is done then their body temperature will drop just from being asleep. Shaving off hair and wetting them (as we clean the skin in preparation for surgery) will further increase the rate of heat loss. We use lots of measures to prevent heat loss (heated table, hot dog warmer, socks, toweling robes, bubble wrap etc) and it is crucial that we monitor that these measures are being effective. Keeping your pet’s body at the correct temperature ensures that the recover quickly from the anaesthetic and reduces the chance of infection or other complications. Once they are awake enough to be moved to recovery, they are placed in a thermal bed (still wearing their towelling robe) to ensure their comfort and warmth.
On top of all the monitoring equipment, your pet’s nurse will be watching them throughout, checking their pulse, respiration, heart. Ensuring everything is going according to plan and keeping the vet informed every step of the way. Once they are happy that your pet has woken up fully, they will then phone you with an update and confirm a time for your pet to be collected.