1. Overview Of Anaesthesia Flashcards
Role of anaesthetists
Anaesthetists are responsible for the peri- operative care of a surgical patient m. This implies that they should be involved in the pre-, infra- and postoperative management of patients, in consultation with other clinicians e.g surgeon, physicians, intensivists, the primary care physician etc.
Define general anaesthesia
General anaesthesia can be defined as a reversible drug induced coma-like state that is characterised by loss of consciousness, loss of recall and variable loss of somatic and autonomic reflexes
What does “anaesthesia” in Greek mean
Without sensation
Division of anaesthetic into three distinct periods
Pre- operative
Anaesthetic
Post- operative
Pre- operative period
pre-operative visit or consultation where the anaesthetist meets the patient, examines them, and plans an anaesthetic appropriate for the specific procedure the patient is undergoing.
Sub-Division of the anaesthetic period
Induction phase
Maintenance phase
Emergence phase
Post- operative
postoperative or recovery period where the patient returns to full physiological functioning.
Anaesthetists as peri- operative physicians
They care for their patients during their operative journey
Anaesthetists are the patient’s guardian during this period and must endeavor to maintain normal physiological functioning whilst administering the anesthetic
things done in the pre- operative visit
- relevant history
- examination of the patient
- special investigations
- inform the patient about the attendant anaesthetic risks
- give outline of the journey through the surgical period
- premedication orders
division of the anesthetic period
- pre induction
- induction
pre induction
- machine, monitoring and equipment check
- identifying the presence of emergency equipment and drugs
- drawing up the drugs to be used
- patient is prepared for anaesthesia
how is the patient prepared for anaesthesia
by establishing venous access and administering pre- induction drugs
what does the administration of induction drugs depend on
on patient-, medical-, or surgical- factors ad well as the knowledge and technical skills of the anaesthetic team
risk of induction
the risks of induction come from:
it is a high risk period
the risks of induction come from:
*equipment and monitor malfunctions,
*failure to recognize airway problems
* untoward reactions to administered drugs
what does induction mean
the transition from an awake to an anaesthetized state
classification of anaesthesia
regional (local)
general
maintenance period
the anaesthesia must be administered adequately to the appropriate level and maintained until the surgery is complete
what must the anaesthetist monitor the patient on
- clinical grounds
- non invasive and invasive monitoring device
- “point of care” blood test
problems that may arise during the maintenance period
- peri operative fluid shifts
- blood loss
-aggravation of pre- existing medical or surgical conditions
how is the reversal period induced
removing maintenance drugs or administering antidotes
emergence or reversal
the patient is allowed to “lighten”, regain spontaneous ventilation and the ability to maintain their own airway and protective reflexes
examples of post- operative placement of the patient
- a recovery area or post anaesthesia care unit prior to returning to the ward (or home)
- a high care unit for more intensive monitoring or pain/fluid management
- the intensive care unit (ICU) for further invasive monitoring and organ support
post operative period
no anaesthetic is complete until the patient is fully recovered from the effects of the anesthetic drugs
patients must be monitored until able to cope will all basic physiological functions
pain management
it is crucial for relieving the patient from discomfort, both physical and psychological
Three main objectives of general anaesthesia
hypnosis
analgesia
immobility/ muscle relaxation
advantage of treat each angle of the triad of anaesthesia with specific drugs
allows a lower total dose of each drug due to synergism and therefore less chance of severe side effects
aim of hypnosis
patients want to be awareness free
aim of immobility/ muscle relaxation
surgeons want patients to be movement free
aim of analgesia
Anaesthetists want the patient to be reflex free
define synergism
an interaction between two or more drugs that causes the total effect of the drugs to be greater than the sum of the individuals effects of each drug
define analgesia
medication that acts to relieve pain
classification of hypnosis
psychological hypnosis
chemical hypnosis
psychological hypnosis
-time consuming
-unreliable (only 10-30% of patients can tolerate surgery)
-expertise not available
division of chemical hypnosis
general anaesthesia
sedation
division of general anaesthesia
intravenous anaesthesia
inhalation anaesthesia
intravenous anaesthesia: one dose
induction agent
intravenous anaesthesia: continuous doses
total intravenous anaesthesia (TIVA)
division of sedation
non- anaesthetic agents
neuroleptic anaesthesia
non- anaesthetic agents
- all general CNS depressants may causes unconsciousness depending on the dose
- benzodiazepines, alcohol, phenothiazine, barbiturates have all been used
-in low doses, some general anaesthetic agents (such as Propofol) can cause reliable sedation without suppressing reflexes or respiration
neuroleptic anaesthesia
-partial sedation whereby consciousness is altered enough to lose comprehension or resistance to procedure
* ketamine
*butyrophenones (droperidol or haloperidol -rarely used nowadays)
how can immobility of the patient be achieved
restraints
deep general anaesthesia
neuromuscular blocking drugs
local anaesthetic
restraints
Some patients, once rendered unconscious, are physically restrained to assist the
surgeon’s view. Be aware of patients’ neurovascular bundles to prevent injury.
deep general anaesthesia
This can be used alone to prevent movement, but this may result in high doses of
drugs causing side effects
neuromuscular blocking drugs
These drugs work on the neuromuscular junction and are divided into two groups:
(a) Depolarising
(b) Non-depolarising
these agents also paralyze the muscles used for respiration, and this artificial ventilation (manual or automatic) is mandatory
local anaesthetic
In the correct place and at the correct strength, local anaesthetics are sufficient to
cause motor nerve blockade with adequate muscle relaxation for surgery
multimodal approach to analgesia
combining several methods of pain
simple analgesics
. paracetamol per os, per rectum or intra-venous (Perfalgan®)
NSAIDs
for surgical inflammatory pain, e.g.
diclofenac
opiates
reduce pain inputs, i.e. inhibit the nociceptive pathway, e.g. morphine.
Many
routes of delivery, e.g. oral, intramuscular, subcutaneous, transcutaneous, epidural
or spinal
local anesthetics
block pain pathways
Serotonin and / or Noradrenaline agonists,
Tramadol
Monitoring
ALL PATIENTS MUST BE MONITORED WHILE RECEIVING PERIOPERATIVE CARE, which
could be seen as adding a fourth corner to the triangle., making it a square or diamond.
