Anaesthesia and how it works
Hello wonderful people of the internet. If you are new here I'm Sam, I'm an aspiring vet currently taking a year out hoping to get a place at university next year! I hope you enjoy this post it's not going to be super long I don't want to put you off, but if you do get bored at any point you can just click off this page, the joys of free will, thank you for taking time to read this and I hope you are having a great day wherever you are in the world. So on with the post.
This week scrolling through Facebook a video kept popping up on my feed and so I watched it the whole way through, it was a short 3 minute video about how anaesthetic works, it was made for a Ted-Ed talk about a year ago and I found it very informative so I'm going to relay the information for you today.
I myself have had 3 general anaesthetics in my life and I've witnessed many more with all of the work experience I carried out. So when you or the animal goes under general anaesthesia they will suddenly become unconscious then afterwards they will wake up as if they'd just been asleep and the operation will have been completed.
This all may seem very simple however when an anaesthetist is calculating a dosage for an animal before an operation, they must take a few things into account, for example the weight of the animal the length of the procedure and the age of the animal. The drug mixture that is made up for the anaesthetic is specific to each animal and can be changed during the procedure which is why checks on vital signs are taken constantly throughout the procedures.
When deciding on anaesthetics there are a few different methods of application that can be used on a patient, these are;
The regional works by blocking the nervous communications between one specific part of the body and the brain, so that the patient can't feel that specific part of the body, because the electrical impulses that would have sent pain messages to the brain are blocked by the anaesthetic acting as a barrier. The barrier works by preventing the carrier proteins in the neurones from transporting the positive particles which therefore means that the membrane remains constantly polarised so no waves of depolarisation can occur hence no nervous impulses. A substance that has been proven to do this is cocaine, nowadays it is sometimes still used however the more common ones often have a very similar chemical structure to cocaine and have the same effect.
For major surgeries a simple regional anaesthetic won't cut it. In these cases inhalation is used because it will block out the entire nervous system. The reason that inhalation works so well for this is because the air breathed in goes straight to the lungs where it diffuses into the circulatory system. Which will then travel to all of the areas of the body and block the nervous communications to the brain. In the past Diethyl Ether was discovered to have these properties because it was taken as a recreational drug, but doctors started noticing that in some cases the people using it couldn't remember what they had done during the episode or explain an injuries obtained during the episode. This then moved onto Nitrous oxide which is still used today however ether derivatives are more common like sevoflurane.
Intravenous often accompanies inhalational, it was developed in the 1870's, some of the key components of this are propofol which increases unconsciousness and an opium derivative like fentanyl to reduce pain. They work on the brain, by changing the brains electrical signals, normally these electrical signals are very chaotic with all of the different parts of the brain communicating with each other. However with these anaesthetics the signals become more organised and less chaotic suggesting that not all parts of the brain are communicating. There is still a lot not known about how this fully works but some anaesthetics bond to the GABAa receptors in the cell membrane of the brains neurones which causes the channel proteins for the negative ions flow into the intermembrane space of the neurone, this negative charge acts as a blanket barrier so that the neurone can't transmit electrical signals, this will be because the equilibrium between the sodium and potassium ions has been distorted.
All the these types combined will deem the patient unconscious and unable to feel pain, the anaesthetics will also work not only on the nervous system but also on vital organs like the heart, lungs and other vital organ. It's surprising to think that we can date early anaesthetics back to ancient Egypt where they used opium poppies, alcohol and mandrake fruit, some other anaesthetics used are some common poisons like hemlock and aconite, these can have major side effects and so can every anaesthetic which is why the combination of the three types and the mixture of drugs has to be carefully calculated for each individual patient. I was watching supervet the other day and they had a dog sedated for some scans, the query was an unexplained pain in this large dogs back right leg, now after the scan Noel manipulated the joints in the back leg, at this the dogs heart rate went up indicating that this was painful, this is the difference between sedation and general anaesthetic and the different levels of general anaesthetic. With this dog they had it under so that it wouldn't move but it could still feel pain so they could see the exact cause of the unexplained pain.
All of this development of anaesthetics has allowed surgeries to become routine and to be carried out quickly and safely, I myself have had three surgeries that have all been keyhole so my scars are very small and it meant I could heal quicker. Having surgeries and putting patients under anaesthetic has become so much safer and common and allowed medicine to develop to save more lives, I think its incredible.
Thank you for reading, hope it wasn't too long and it was informative. I hope you all have an amazing week and remember to count your blessing and be thankful for what an amazing life you have. Again thank you for reading and I'll see you next week.
This week scrolling through Facebook a video kept popping up on my feed and so I watched it the whole way through, it was a short 3 minute video about how anaesthetic works, it was made for a Ted-Ed talk about a year ago and I found it very informative so I'm going to relay the information for you today.
I myself have had 3 general anaesthetics in my life and I've witnessed many more with all of the work experience I carried out. So when you or the animal goes under general anaesthesia they will suddenly become unconscious then afterwards they will wake up as if they'd just been asleep and the operation will have been completed.
This all may seem very simple however when an anaesthetist is calculating a dosage for an animal before an operation, they must take a few things into account, for example the weight of the animal the length of the procedure and the age of the animal. The drug mixture that is made up for the anaesthetic is specific to each animal and can be changed during the procedure which is why checks on vital signs are taken constantly throughout the procedures.
When deciding on anaesthetics there are a few different methods of application that can be used on a patient, these are;
- Regional
- Inhalational
- Intravenous
The regional works by blocking the nervous communications between one specific part of the body and the brain, so that the patient can't feel that specific part of the body, because the electrical impulses that would have sent pain messages to the brain are blocked by the anaesthetic acting as a barrier. The barrier works by preventing the carrier proteins in the neurones from transporting the positive particles which therefore means that the membrane remains constantly polarised so no waves of depolarisation can occur hence no nervous impulses. A substance that has been proven to do this is cocaine, nowadays it is sometimes still used however the more common ones often have a very similar chemical structure to cocaine and have the same effect.
For major surgeries a simple regional anaesthetic won't cut it. In these cases inhalation is used because it will block out the entire nervous system. The reason that inhalation works so well for this is because the air breathed in goes straight to the lungs where it diffuses into the circulatory system. Which will then travel to all of the areas of the body and block the nervous communications to the brain. In the past Diethyl Ether was discovered to have these properties because it was taken as a recreational drug, but doctors started noticing that in some cases the people using it couldn't remember what they had done during the episode or explain an injuries obtained during the episode. This then moved onto Nitrous oxide which is still used today however ether derivatives are more common like sevoflurane.
Intravenous often accompanies inhalational, it was developed in the 1870's, some of the key components of this are propofol which increases unconsciousness and an opium derivative like fentanyl to reduce pain. They work on the brain, by changing the brains electrical signals, normally these electrical signals are very chaotic with all of the different parts of the brain communicating with each other. However with these anaesthetics the signals become more organised and less chaotic suggesting that not all parts of the brain are communicating. There is still a lot not known about how this fully works but some anaesthetics bond to the GABAa receptors in the cell membrane of the brains neurones which causes the channel proteins for the negative ions flow into the intermembrane space of the neurone, this negative charge acts as a blanket barrier so that the neurone can't transmit electrical signals, this will be because the equilibrium between the sodium and potassium ions has been distorted.
All the these types combined will deem the patient unconscious and unable to feel pain, the anaesthetics will also work not only on the nervous system but also on vital organs like the heart, lungs and other vital organ. It's surprising to think that we can date early anaesthetics back to ancient Egypt where they used opium poppies, alcohol and mandrake fruit, some other anaesthetics used are some common poisons like hemlock and aconite, these can have major side effects and so can every anaesthetic which is why the combination of the three types and the mixture of drugs has to be carefully calculated for each individual patient. I was watching supervet the other day and they had a dog sedated for some scans, the query was an unexplained pain in this large dogs back right leg, now after the scan Noel manipulated the joints in the back leg, at this the dogs heart rate went up indicating that this was painful, this is the difference between sedation and general anaesthetic and the different levels of general anaesthetic. With this dog they had it under so that it wouldn't move but it could still feel pain so they could see the exact cause of the unexplained pain.
All of this development of anaesthetics has allowed surgeries to become routine and to be carried out quickly and safely, I myself have had three surgeries that have all been keyhole so my scars are very small and it meant I could heal quicker. Having surgeries and putting patients under anaesthetic has become so much safer and common and allowed medicine to develop to save more lives, I think its incredible.
Thank you for reading, hope it wasn't too long and it was informative. I hope you all have an amazing week and remember to count your blessing and be thankful for what an amazing life you have. Again thank you for reading and I'll see you next week.
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