Different methods of anaesthesia Flashcards
(37 cards)
What is anaesthesia?
Means loss of sensation which is achieved with drugs called anaesthetics
Why is anaesthesia performed?
For medical reasons so that surgery/specific procedures can be carried out on patients and their pain can be controlled3
Why is sedation performed?
A premedication prior to induction of general anaesthesia or used in a combination with local anaesthetic to negate the need for general
What is a sedative drug?
One that produces drowsiness and calmness
What is general anaesthesia?
An induced, reversible state of unconsciousness & provides analgesia and muscle relaxation
What is the “triad of anaesthesia”?
Unconsciousness
Relaxation
Analgesia
What does general anaesthesia cause?
Depression of normal physiological functions
Dose-dependant depression of the CNS to reduce motor responses to noxious stimuli but also affects important functions such as breathing
How can general anaesthesia be administered?
IV or inhalation - or a combination of both
What is dissociative anaesthesia?
A state where the patient is less aware of what is happening around them, however they are not rousable
When is dissociative anaesthesia used?
As part of a sedation plan for minor procedures
What do dissociative drugs do to patients?
Produce a feeling of detachment from the environment and themselves by altering the conscious perception of sight, sound & touch from the other part of the brain
What is dissociative anaesthesia characterised into?
Catalepsy
Catatonia
Analgesia
Amnesia
What reflexes are maintained during dissociative anaesthesia?
Pharyngeal
Laryngeal
Corneal
Palpebral
Swallowing
What is the most common dissociative drug used?
Ketamine
What is Ketamine used in combination with?
An alpha-2 agonist (e.g. medetomidine) or a benzodiazepine (e.g. midazolam)
What does ketamine not provide?
Muscle relaxation
What is local anaesthesia?
When local anaesthesia drugs are administered to interrupt the signal from a specific nerve to the brain
How do local anaesthetics work?
Reversibly bind to the sodium channels on the nerve cell
The sodium channels open along the axon like a mexican-wave which allows sodium to rush into the cell and carry on the impulse (action potential)
Once the local anaesthesia binds to the sodium channel, it interrupts the transmission of the impulse it is trying to send (sensory to motor)
What is local anaesthesia considered as?
The only “true” analgesic as it is used to prevent the pains signal from reaching the brain
How can local anaesthesia be provided?
Topical
Intradermal
Local infiltration
Intra-articular
Perineural
Intravenous regional anaesthesia
Epidural
How is topical local anaesthesia used?
Has limited use and is usually confined to the eye & mucous membranes of the nasopharynx, larynx, penis, vagina, rectum & urethra
Applied as gel or a solution or by aerosol depending on the area
What are examples of topical local anaesthesia?
Lignocaine spray (cats)
Amethiocaine drops (eyes)
EMLA cream (rabbit ears, cannulation)
What is an intra-articular block?
Local anaesthetic instilled into the affect joint cavity
Commonly use post-surgery
What is infiltration local anaesthesia?
Involves the injection of local anaesthetic intradermally/subdermally