Anaesthetics Flashcards
side effects of propofol?
resp depression
cardiac depression
pain on injection
side effects of volatile agents e.g. isoflurane?
nausea and vomiting
cardiac and resp depression
vasodilatation
hepatotoxicity
why does anaesthesia cause a drop in BP?
results in vasodilatation, reducing TPR
why are the eyes taped closed when under GA?
as loss of muscle power, so reduce risk of corneal abrasion
CI to spinal blocks?
anticoagulation
local infection
what to do at the end of anaesthesia?
change inspired gases to 100% O2 only
discontinue any anaesthetic infusions and reverse muscle paralysis
place ptnt in recovery position once spontaneously breathing, and give O2 by face mask.
signs of LA toxicity?
perioral tingling and paraesthesia
progressing to drowsiness, seziures, coma and CR arrest.
causes of post-op confusion?
hypoxia e.g. from atelectasis, pneumonia drugs- opioids, sedatives urinary retention infection MI/stroke alcohol withdrawal liver/renal failure
why might ptnts BP be increased post-op?
pain
idiopathic hypertension e.g. missed medication
urinary retention
inotropic drugs
what can precipitate decrease in Na+ post-op?
peri-op nausea, opioids, pain and chest infection
agents used to reverse muscle relaxation?
anticholinesterase e.g. neostigmine
BUT cannot reverse blockage induced by suxamethonium, and would actually potentiate its action!
how can therapeutic effect of local anaesthetic be prolonged?
injection of adrenaline- vasoconstriction and so reduce blood flow at site of LA injection to reduce rate of absorption of LA, reduce toxicity and extend duration of action.
why are ptnts NBM pre-op ( at least 6 hrs for food, and 2 hrs for fluids)?
to reduce risk of regurgitation and aspiration of gastric acid at anesthesia induction
** if risk ptnt has eaten before op, must do rapid induction?**
why must ptnt be sat upright in recovery room?
allow diaphragm to flatten to ease breathing and so maintain appropriate SpO2
reduce risk of regurgitation and aspiration
which ptnts may be given antacids as premed to reduce risk of regurgitation and aspiration of gastric acid at induction of anaesthesia?
pregnant women- *progesterone, SM relaxation, increase reflux?
ptnts requiring emergency surgery
ptnts with hiatus hernia
morbidly obese ptnts
rationale behind giving analgesia as a pre-med?
stop sensitisation of pain-conduction pathways that occurs with tissue damage during surgery, so postop pain will be reduced, AND prevent chronic pain.
in which ptnts might antibiotics be given as a pre-med?
prosthetic or diseased heart valves
undergoing joint replacement
or bowel surgery
thiopental can be used for rapid induction. what dose is given, speed of induction and duration of action?
2-6mg/kg, propofol= 1.5-2.5 mg
20.30s
lasts 9-10 mins
considerations with use of thiopental for IV induction
ptnts may taste garlic or onions!
cumulative, delayed recovery after repeat doses
why are barbiturates NOT used for TIVA?
prolonged recovery as accumulate in body e.g. thiopental
why should LAs containing vasoconstrictors NOT be used around extremities e.g. fingers and penis?
risk of vasoconstriction causing tissue necrosis
difference in speed of onset and duration of action between lidocaine and bupivacaine?
bupivacaine has slower onset but longer duration of action, widely used in nerve blocks, epidural and spinal anaesthesia, part. in obstetrics.
define atelectasis *
state of lung collapse, can be partial or whole
alveolar collapse, usually due to bronchial secretions
prevent by physio pre and post op
+ve pressure ventilation may be required if severe
