Perioperative Care Flashcards
Name some induction agents
Propofol, sodium thiopentone, ketamine, etomidate
Describe the indications for the various induction agents
Propofol: ITU sedation and day case surgery
sodium thiopentone: RSI
ketamine: haemodynamic instability
Suxamethonium - RSI (muscle relaxant)
What are the pros and cons of propofol
- myocardial depression
- vasodilator
+ antiemetic properties
+ quickly metabolised
What are the pros and cons of sodium thiopentone
- marked myocardial depression
- no analgesic effects
- poorly metabolised
+ rapid onset
What are the pros and cons of ketamine
- causes dissociative nightmares
+ not much myocardial depression
+ strong analgesic
What are the pros and cons of Etomidate
- no analgesic properties
- vomiting
- adrenal suppression
+ not much myocardial depression
What are the 2 types of neuromuscular blocking agents.
Give examples
State their MOA
Depolarizing: Suxamethonium
- acts by binding to the nicotinic ACh receptor and repeatedly depolarizing it
Non-depolarizing: rocuronium, atracurium, vecuronium
- competitive antagonist at the nicotinic ACh receptor
What are the contraindications to using a depolarizing paralytic agent?
penetrating eye injury
acute closed angle glaucoma
burns
cord injury/paraplegia
What are the ADRs of depolarizing paralytic agents?
Malignant hyperthermia
Hyperkalaemia
In which group of patients should you be cautious with when using non-depolarizing paralytic agents
Myasthenia gravis - they will be over sensitive and so have a prolonged recovery
What are the ADRs of non-depolarizing agents?
Hypotension
What are the risk factors/ causes of lidocaine toxicity? Why?
hepatic dysfunction (hepatic metabolism)
metabolic acidosis (causes detachment from protein)
Low protein state (protein bound)
Given IV
How does lidocaine toxicity present?
CNS overactivity and then depression
Arrhythmia’s
What common drugs does lidocaine interact with?
b-blockers
Ciprofloxacin
Phenytoin
What is the reversal agent used in lidocaine toxicity?
20% lipid emulsion IV
Compare the maximum lidocaine you can use with or without adrenaline
without: 3mg/kg up to 200mg
with: 7mg/kg up to 500mg
What are the contraindications to using adrenaline with lidocaine?
in hand surgery (as end arteries)
MAOs or TCAs
What is an indication and a contraindication to using Bupivacaine as a LA agent?
Often used in wounds at the end of surgery as it is long acting
Not to be used in regional blocks as is cardiotoxic so too risky if the tourniquet fails
When is cocaine used as a LA agent?
ENT surgery as it is rapid acting and causes marked vasoconstriction
When and why is Prilocaine used as a LA agent?
Regional blocks as it is the least cardiotoxic of all agents in case the tourniquet fails
How is hypothermia prevented?
Don’t take to theatre unless >36
Bair Hugger used
Warmed fluids
Why is hypothermia bad?
- causes coagulopathy
- causes vasoconstriction which leads to poor healing and wound infection as reduced white cell delivery
- prolongs drug actions meaning a longer recovery
What is a Kochers incision?
Under right subcostal margin used for cholecystectomy
What is a Lanz and a Gridiron incision?
RLQ
Lanz is horizonal
Gridiron is oblique
What is a Pfannensteil incision?
Suprapubic transverse
What is a McEvedy’s incision?
In the groins - used for emergency hernia repair
What is malignant hyperthermia?
Autosomal dominant condition in which there is excessive release of Ca from the SR of skeletal muscle in reaction to volatile agents such as Suxamethonium and halothane
How does malignant hyperthermia present?
Hyperpyrexia Muscle rigidity \+++ CK Tachycardia and arrhythmias Raised ETCO2
How is malignant hyperthermia managed?
Dantrolene
What can cause a paralytic ileus?
Bowel handling Leak or intra-abdominal collection MI Stroke AKI Pneumonia
What examination finding is key in paralytic ileus?
Absent bowel sounds
What drugs slow wound healing?
NSAIDs
Steroids
Immunosuppressants and cancer drugs
Describe the VTE prophylaxis used for
a) NOF fracture
b) hip replacement
c) knee replacement
a) 1 month LMWH
b) 10 days LMWH then 1 month aspirin
c) 14 days aspirin
Aside from drugs, what other measures can minimise VTE risk?
Pneumatic compression devices
Anti-embolism stockings
Describe the grades of ASA physical status classification
1: no limitations
2: mild systemic disease with no limitations
(smoking, alcohol, BMI 30-40)
3: systemic disease resulting in limitations
(alcohol dependant, BMI >40)
4: severe disease with constant threat to life
(MI <3 months ago)
5: won’t live without surgery
6: brain dead - surgery is for organ removal
What are your differentials for post-op pyrexia?
Infection
- catheter
- wound
- lines
- collection or leak
What are your differentials for post-op confusion?
hypoglycaemia
electrolyte imbalance
infection
drugs
What can cause post-op hyponatraemia?
How does it present?
Paralytic ileus (due to third spacing) Fluid overload
Confusion and hypotension
What can cause post-op oligouria?
pre: Hypovolaemia and sepsis
renal: NSAIDs and IV contrast
post: Catheter blocked
What cause cause post-op hypotension? What would you be looking for to point towards these causes?
hypovolaemia: abdo distension, drains
cardiogenic: raised JVP, ECG abnormalities
septic: fever, flushed
What can cause post-op reduced saturations?
respiratory depression
fluid overload
acidotic due to AKI
atelectasis
What is atelectasis? What does it lead to?
basal small airway collapse leads to secretions accumulating causing hypoxaemia and infection
How does atelectasis present?
Within 24 hours post-op
Increased RR, reduced saturations
Fine crackles
Low grade fever
What are the advantages and disadvantages of a central line at the femoral vein?
+ easier insertion
+ iatrogenic vessel damage easier to manage as compressible
- infection
