Anaesthetics Flashcards
Define general anaesthesia
Drug induced, controlled, reversible LOC
Premedication - examples used in anxious patients
Temazepam
Midazolam
Premedication - what may you give to reduce gastric activity?
Ranitidine
When is pre-oxygenation used?
When ventilation - difficult
Anaesthetics used for IV induction (2)
Propofol
Fentanyl
What is placed after IV induction?
LMA/ETT
Agents used in gas maintenance
Volatile agents
e.g. isoflurane/halothane
what is TIVA
Total Intra Venous anaesthesia
What drug is most commonly used in TIVA
Propofol
What are the 4 stages of anaesthesia
Anaesthesia stage
Excitement stage
Surgical anaesthesia
Emergence
2 groups of adjuncts used in anaesthetics
Mm relaxants (NM blocking agents) Anti-nociception
E.g.s of NM blocking agents (3)
Atracurium
Suxamethonium
Rocuronium
Anti-noception Dx e.g.s
Opioids
Paracetamol
NSAIDS
How is the potency of inhalation induction quantified?
MAC - Minimum alveolar concentration
Indications inhalation inductions (2)
Children/needle phobias
Spontaneous resp maintained (when difficult intubation expected)
How are volatile agents in inhalation induction delivered?
Vaporizer
How are volatile agents in TIVA delivered?
Microprocessor-controlled syringe pump
Indications TIVA (4)
Preference
Rapid recovery
Decr PONV
Laryngoscopy where volatile agents may ppt airway irritation
What is RSI
Delivery of rapid acting mm relaxant immediately after induction agent
When is RSI used?
To rapidly prod optimum conditions for intubation in ER situations
How does LA work
Blocks conduction of nn impulses along axons
What can you use as an adjunct to LA to vasoconstrict
Adrenaline
Why use adrenaline w/ LA?
Increases potency and duration
2 types of regional anaesthesia
Central/neuraxial
Major nn/regional blocks
E.g.s of central regional anaesthesia
Spinal
Epidural
e.g.s of major nn regional anaesthesia
Brachial plexus
Femoral
Sciatic
Max safe dose in regional anaesthesia?
3mg/kg lignocaine
Where is spinal anaesthesia injected?
Into CSF in subarachnoid space
Duration spinal anaesthesia
1-4hrs
How to measure the level anaesthetised in spinal anaesthetics?
Ice spray
Continuous Monitoring during spinal anaesthesia (4)
ECG
BP
RR
SPo2
C/I spinal anaesthesia (5)
Incr ICp Hypovolaemia Surgery above thorax Local/systemic infection > 2hrs long
How are epidurals performed
Epidural catheter inserted into epidural space
LA injected via pump
In an epidural, how long does it take for anaesthesia to be achieved?
45 minutes
Monitoring epidural anaesthesia (4)
Continuous ECG, BP, RR, SPo2
Complications epidural anaesthesia (3)
Decr BP,
resp depression
CSF puncture –> headache –> total spinal affect
Advantages of regional anaesthesia over GA (5)
Decr risk infections Decr CV complications Decr PONV Decr pain Decr DVT risk
Affects of GA on the CV system (4)
Decr myocardial comtractility hence decr CO
HOTN
Reduction in O2 delivery + demand
Arrythmias
Affect of GA on the resp system (5)
Resp depression --> reduced FRC Worse VQ matching Atelectasis Laryngospasm --> airway obstruction Prolonged pain + inflamm
Affect of GA on airway (2)
Loss of tone
Loss of reflexes
Affect of spinal on CV system (2)
Vasodilatation
Decr HR
Affect of spinal on resp system
Resp depression b/c intercostal mm relax
Risks - GA - common (4)
PONV
Pain
Sore throat
Teeth knocked out
Other, less common risks GA (5)
Anaphylaxis Awareness when under GA Aspiration CV issues Stroke
RF Awareness when under GA (3)
Emergencies
Prev awareness
Use of mm relaxants
RF spinal anaesthesia (5)
Neuro disorder due to trauma If high spinal block - depression of BS Urinary retention + bladder damage CV issues Spinal headache
Current health questions to ask a patient in pre-op assessment (5)
Recent/current illness ET + what makes them stop Sleep apnoea Smoking/alcohol Pregnant
Relevant med/DHx to ask in anaesthetics Hx (7)
DM HTN IDA Asthma/COPD CVD IHD Allergies
Anaesthetics Hx to ask (2)
Prev anaesthetics + reactions
Any FHx
O/E pre-op assessment (5)
Neck movement Jaw opening Dentures/crowns.caps Airway assessment BMI
What classification is used in Ananaesthesia for airway
Mallampati
What classification is used to determine risk?
ASA
ASA grade 1
Normal healthy pt
ASA grade 2
Mild systemic disease
e.g. smoker, pregnant, >30BMI
ASA grade 3
Severe systemic disease
(Isnt incapacitating)
E.g. COPD, BMI >40, ESRD
ASA grade 4
Severe systemic disease
Constant threat to life
E.g. DIC, sepsis, recent MI
ASA grade 5
Moribound patient not expected to survive 24 hrs w/o op
E.g. ruptured AAA
ASA grade 6
Brain dead
Why would you take a pre-op FBC?
IDA - higher risk of post-op transfusion after surgery
For which patients do you need to take a pre-op U+E?
Those on: digoxin, diuretics + steroids
DM, renal disease, V+D
For what patients do you need to take LFT’s pre-op?
Known hepatic disease
Alcohol Hx
Metastatic disease
Which patients do you take BM for pre-op?
Diabetics
LT steroid users
Which pt do you take clotting bloods for pre-op?
FH/PMH bleed
Current anticoagulation
Which patients do you take a CXR for pre-op?
Hx cardio/resp disease or known malignancy
Suspect chest infection
What screening tool is used to screen OSA pre-op?
STOP BANG
Why must patients be starved before surgery?
Due to loss of protective cough reflex during anesthesia
How long before an op must a patient be starved of solid food?
6 hours
How long before an op must a patient stop being breastfed?
4 hours
How long before an op must a patient be starved of fluids?
2 hours
Things that delay gastric emptying (4)
Pain
Illness
Obstruction
Opioids
Patients that lose barrier pressure and hence are more at risk of aspirating? (2)
Hiatus hernia
Symptomatic reflux
Pre-op things to be aware of - diabetic patient
Minimise fasting - 1st on list
If well controlled DM - omit meds on day of op
If poor controlled DM/ER - variable rate infusion needed
Pre-op assessment DM patient (4)
BM
Urinalysis
CK
Electrolytes
Peri-op things to be aware of - DM (3)
Consider RSI to reduce aspiration risk
Reg monitor BM
If gluc >10 - insulin regimen
