4: Peri-Operative Medicine Flashcards
what are causes of hypothermia in surgery
- higher ASA
- major surgery
- low body weight
- large amount of cold IV infusions/blood transfusion
- exposure to cold theatre environment
- muscle relaxanats prevent shivering
- spinal/epidural anaesthesia
how does spinal/epidural anaesthesia cause hypothermia
prevents peripheral vasoconstriction via reduced sympathetic tone
- increased heat loss at the peripheries
ASA I
healthy
non smoker
non drinker
BMI <30kg/m
ASA II
- mild systemic disease e.g. smoke, social alcohol consumption
- pregnant
- obese BMI 30-40
- well-controlled DM, HTN, mild lung disease
ASA III
- poorly controlled DM, HTN, COPD
- morbidly obese >40
- alcohol dependence or abuse
ASA IV
- severe systemic disease e.g. ongoing cardiac ischaemia
- recent MI
- sepsis
- end-stage renal disease
ASA V
patient who are unlikely to survive without surgical intervention
- e.g. major trauma or significant bleeding
ASA VI
declared brain-dead patient whose organs are being removed for donation
what are pre-op guidannces for starvation of
- solids
- clear liquids
- solids: 6 hours
- clear liquids: 2 hours
what are the advantages of spinal anaesthetics
- conscious during procedure e.g. during birth
- can use in COPD patients as no interference with airways or ventilation
compare and contrast spinal vs epidural
spinal
- delivers drug to subarachnoid space into CSF and acts on spinal cord directly
- profound block of all motor and sensory function below level of injection
- shorter procedures
- onset of analgesia ~5 mins
- can be given at cervical, thoracic or lumbar site
epidural:
- delivers drugs outside the dura and has main effects on nerve roots leaving dura
- blocks a band of nerve roots with normal function around site of injection
- can be given as catheter
- onset of analgesia ~25-30 mins
- below L2
what is the function of glycopyrronium
decreases secretions in the airways
what is thiopental and what is its side effect
induction agent
laryngospasm
what is malignant hyperthermia/hyperpyrexia
- hereditary condition that causes an adverse reaction to anaesthetic
- mainly precipitated by halothane or suxamethonium (volatiles)
what are the symptoms/complications of malignant hyperthermia
- severe muscle rigidity/spasms
- tachycardia
- low O2, high CO2
- arrhythmias
- metabolic acidosis
how is malignant hyperpyrexia corrected
dantrolene!
- skeletal muscle relaxant
- active cooling
- ITU care
in what setting is administration of local anaesthetic not suitable
acidic e.g. abscesses as they are basic solutions
what are the symptoms of local anaesthetic toxicity and how is it treated
- peri-oral tingling
- paraesthesia
- progress to drowsiness, seziures, coma
✅ lipid emulsion
describe the features of crystalloid IV fluids
- contains electrolytes
- metabolic substrates
- small molecules able to diffuse through cap wall
- suitable if cells are dehydrated
- e.g. Hartmann’s (most similar to plasma without glucose) or NaCl
describe the features of colloid IV fluids
- large molecules that don’t readily pass through cap walls
- remain in intravascular space (blood)
how long before surgery should oral contraceptives be stopped and why
4 weeks before elective due to risk of VTE
what is the gold standard of detecting oesophageal intubation
capnography
- if tube is in the oesophagus then there will be no end-tidal carbon dioxide as there is no ventilation
what is pseudocholinesterase deficiency
- increase duration of action of muscle relaxants e.g. suxamethonium
- resp arrest inevitable unless pt mechanically ventilated
what are contraindication of neuraxial blocks
- infection at site of injection
- uncorrected hypovolaemia as it cases vasodilation
- increased intracranial pressure
what are risk of neuraxial blocks
- postudural puncture headache due to hypotension
- epidural haematoma
- cauda equina syndrome
- total spinal anaesthesia
