Module 1: overview of anaesthesia Flashcards
True or false. Anaesthesia includes acute pain management but not chronic
False, anesthesia includes acute and chronic pain management
what part of the operation/surgery do anesthesiologists form part of
pre-operative, intra-operative and post-operative
Who forms part of the team in surgery
surgeons, anesthetists, nurses and porters
what are the 2 types of anesthesia?
General and local/regional
what is general anaesthesia
it is an unconscious patient (induced coma) with inhalational or IV drugs. Depending on surgery the patient may need to have assisted ventilation. ANALGESIA NEEDS TO BE ADMITTED SEPERATELY
What is local/regional anaesthesia?
part of the body is rendered insensitive to pain/sensation by blocking nerves. PATIENT IS FULLY CONCIOUS. specific nerves may be blocked or whole sections, includes neuraxial blocks
what is in the triad of anaesthesia
hypnosis, analgesia and immobility
what does hypnosis entail
Loss of consciousness achieved by inhalation or IV drugs. Usually induced by IV and maintained by inhalational. Does not cause anaelgesia, only hypnotic. If there is pure regional anesthesia the patient will still be awake.
What does analgesia ential
Body still experiences pain under general anaesthesia. Additional analgesics are given (usually IV). Typically fentanyl or morphine is used (strong opiates), REGIONAL ANAESTHESIA (NERVE BLOCKS) ADDED.
Why is it necessary to add analgesia when inducing
Pain activates the sympathetic nervous system which can be deleterious.
What does immobility entail?
Immobile surgical field is essential esp in large body cavity surgeries like abdomen or thorax or delicate microsurgeries. Large body cavity surgeries require neuromuscular blockers which results in patient being intubated and assisted ventilation.
what type of anaesthesia causes a degree of muscle relaxation without need to be assisted with ventilation
deep general anesthesia
what forms part of the perioperative journey?
induction, maintanace and emergence
What happens during pre-induction
patient is assessed, consent given, theatre prepped, equipment checked.
IV access achieved in adults
Pre-induction drugs given (sedatives) for anxiolysis
Patient connected to monitor
Pre-oxygenated
given opiods pre-emptively
What happens during induction
Usually with IV drugs/ some inhalational drugs.
LOC confirmed
Anaethetist responsible for maintaining airway with definitive airway strategy like supraglottic device, mask ventilation or endotracheal tube.
If intubation is required give neuromuscular blocker 1-5min before
What happens during maintenance?
Done by inhalational drugs(propofol can given via infusion instead).
ventilator settings adjusted if used
Additional monitoring may be sited or be used
surgical area is prepared + cleaned
WHO surgical safety checklist
monitor throughout surgery
What happens during emergence
surgery is concluded
returning control of respiration is crucial prior to emergence
muscle relaxant =reversed
respiration and oxygenation must be adequate
anesthetic is discontinued
airway devices removed
what are the 4 stages of general anaesthesia
Stage 1: “Analgesia” → from induction to loss of consciousness
Stage 2: Excitatory phase → paradoxical disinhibition (excitement, hiccupping,
swallowing, writhing about)
Stage 3: Surgical anaesthesia → eyeballs become fixed, diaphragmatic respiration
Stage 4: Overdose: diaphragmatic paralysis, loss of all reflexes → death
In what order are reflexes lost in anaesthesia
Voluntary control of eye movement
Eyelash reflex
Lid reflex
Swallowing, retching and vomiting
Conjuctival reflex
Muscular tone
Corneal reflex
Glottic reflexes and control of respiration
Pupillary light reflex
What entails recovery from anaesthesia
patient regains consciousness
anaesthetic drugs dissociates from binding site-no specific antidote for IV or inhalational drugs
Neuromuscular blockers require antidote
what forms part of the post-operative management
majority will wait in recovery area and moved to ward
day cases go home
special care required goes to ICU
What are the 3 main areas to focus on in pre-operative assessment
medicolegal requirement(Consent)
Identifying chronic diseases or risk factors
Identifying areas which may require optimization before surgery
What is the end goal of pre-operative assessment?
appropriate anesthetic plan
What are the aims of preoperative visit?
anaesthetic plan
baseline physiological state
risk factors
optimizing conditions
prepare patient psychologically
What patient considerations should you take into account?
Medicolegal documents
History: coexisting disease, allergies, medications, prior surgeries
examination esp airway
When is a patient for elective surgery seen?
day before in ward or morning of surgery
when is a patient seen for urgent/emergency surgery?
in front room/induction room
when is a critical ill patient seen?
rushed to theatre with very little time to be seen
what surgical considerations do you need to take into account?
Urgent/elective surgery: urgent has less time to assess=> RISK
Type of procedure: superficial or deep
Location of surgery
Positioning
what is the required fasting period for solid foods/formula milk?
6hrs
what is the fasting period for breast milk?
4hrs
What is the fasting period for clear fluid?
2hrs
What are the risk factors for aspiration?
full stomach
Pregnancy
Increased abdo pressure: masses, ascites, obesity
Autonomic neuropathy in diabetes
renal failure
Gastric pathology like GERD, hernia, PUD
what special investigations might be needed?
FBC
Blood cross match
U&E: hpt, renal disease, elderly
ECG: elderly, cardiac pathology, IHD
CXR: resp/cvs disease
ECHO: valve disease
What is ASA classification I
normal healthy patient. Mortality rate: 0.06%-0.08%
What is ASA classification II
mild systemic disease and no functional limitations. Mort rate: 0.27%-0.4%
What is ASA class III?
moderate to severe systemic disease that results in some
functional limitation, but not incapacitating
MORT RATE: 1.8-4.3%
What is ASA IV?
severe systemic disease that is a constant threat to life and
incapacitating
MORT RATE: 7.8-23%
What is ASA V
moribund patient that is not expected to live for more than 24 hours with or
without the surgery
MORT RATE: 9.4-51%
What is ASA VI?
brain-dead patient whose organs are being harvested
What is ASA E?
EMERGENCY
What are the four parts of an anesthetic plan
Premedication: sedation, anxiolysis, regular medication, preemprive analgesia, antiemetics
Type of analegesia: general, local, regional, conscious sedation
Intraoperative management: monitoring, positioning, fluid management, airway management
Post-operative care: pain control, placement
In a patient who received neuromuscular blocker as analgesia, what is used to check depth of analgesia?
Activation of sympathetic nervous system
What is the most important reflex for anesthetists to look for?
Loss of glottic reflex. In deep anesthesia it is the loss of medullary respiration
