anaesthetics 2 - The conduct of general anaesthesia Flashcards
What does the anaesthetist actually do?
pre-op assessment and care critical and intensive care pain management anaesthesia post-op care
Process of anaesthesia
pre-op assessment preparation induction maintenance emergence recovery post op care and pain management
Preparation for anaesthesia
planning - right patient - right operation - correct side - pre medication - right equipment - right personnel - drugs drawn up - IV access - monitoring
Induction of anaesthesia
quietness with a gas or IV agent
IV agent used in induction of anaesthesia
Propofol and thiopentone
IV induction of anaesthesia
rapid, 1 arm brain circulation time 20s, no obvious planes, easy to overdose, rapid loss of airway reflexes, apnoea common
Gas induction of anaesthesia
halothane in young children, obvious planes of anaesthesia, venous access hard - IVDA
Planes of anaesthesia
analgesia/sedation
excitation
anaesthesia
overdose
Induction - monitoring conscious level
loss of verbal contact movement respiratory processed EEG - BIS stages/planes of anaesthesia
Is airway management required in GA?
yes always
Simple airway manoeuvres
head tilt, chin life, jaw thrust - triple airway manoeuvre
Anaesthetic face mask
identical to those in resus
contoured to face for gas tight seal
size from neonatal to large adult
oropharyngeal airway
Guedel in US - rigid plastic
only tolerated if unconscious
What would an oropharyngeal airway cause in an awake patient?
laryngospasm
Laryngeal mask airway
cuffed tube with mask over glottis
maintains but not protect airway
Resuscitation device - LMA
I-gel
easy insertion
not protect from aspiration
Airway complications - obstruction
ineffective triple airway manoeuvre
airway device malposition
laryngospasm
laryngospasm
forced reflex adduction of vocal cords
complete airway obstruction
airway stimulation in light patients
often unrelieved by simple manoeuvres
Airway complications - aspiration
anaesthesia means loss of protective airway reflexes egg gag, cough
foreign material in lower airway eg gastric content
Difference between maintained and protected airway
maintained - open and unobstructed
protected - only cuffed tube in trachea protects airway
Endotracheal intubation
cuffed tube in trachea - oral route
laryngeal reflexes must be abolished
laryngoscope, muscle relaxant, position
Is endotracheal intubation able in awake patients?
yes with LA and fibre optics
5 reasons to intubate
- protect airway from gastric contents
- muscle relaxation, artificial ventilation
- shared airway with risk of blood contamination
- tight control of blood gases needed
- restricted airway access
Risks to unconscious patient
airway - temperature - pressure areas - consent and identify - VTE - loss of protective reflex eg corneal - patient position
Continuing anaesthesia
care, muscle relaxation and analgesics
monitor, fluid, documentation
Monitoring patient includes…
basic: SpO2, ECG, FiO2, ETCO2, Nibp respiratory, temperature, urine output, NMJ invasive venous/arterial processed EEG, agent monitoring ventilator disconnect
Anaesthetic complications
ABC, technique/position, awareness
risk factors for being awake during surgery
paralysed and ventilated, previous episode of awareness, chronic CNS depressant, cardiac and trauma surgery
Emergence/awakening
muscle relaxation reversed anaesthetic agents off resume spontaneous respiration return airway reflexes/control extubation
conduct of LA
same level of care
IV access, monitoring, presence of anaesthetist
spinal, epidural, plexus block, nerve block
Recovery
a dedicated area with trained staff
many not regained consciousness or airway control
ABC, pain, N&V, discharge back to ward
