other stuff from past papers

Question 1

drugs that can be given via epidural and spinal route…

Answer 1

local anaesthetic agents - bupivacaine, lidocaine
opioids - morphine, fentanyl, diamorphine
adjuncts - clonidine, dexametomidine, ketamine
steroid

also spinal route
intrathecal antibiotics and chemotherapy agents

Question 2

what are the difference between epidural and spinal routes..

Answer 2

anatomical difference - around dura, inside dura (epidural vs subarachnoid space )
dosing differences
intrathecal has faster onset

Question 3

properties of an ideal opioid given epidurally..

Answer 3

potent
rapid onset
quick clearance but enough time to not need regulalry topping up
minimal side effects - resp depression, N&V
actions remain locally
minimal histamine release
Doesn’t need liver to active e.g codeine

diamorphine most closely resembles this

Question 4

compare fentanyl and diamorphine as opioids for epidural analgesia..

Answer 4

• fentanyl is more potent and more rapid in onset - due to highly lipophillic nature
• however diamorphine has a longer duration of action
• diamorphine has a higher incidence of resp depression and addiction

Question 5

compare the side effect profile of when opioids are given via epidural route vs systemically IV

Answer 5

IV - higher risk of resp depression, because generally larger doses used and less targetted. similarly more sedation, histamine release, hypotension and N&V

however epidural associated with risk of epidural - infection, dural headaches, haematoma, nerve injury

Question 6

where are the main opioid receptors located?

Answer 6

U - cortex, thalamus, limbic, spinal cord, GI
delta - spinal cord, cortex, limbic
kappa - hypothalamus , spinal cord
NOP - cortex, spinal cord, GI , limbic

Question 7

Why is it important to prescribe O2 and what aspects?

Answer 7

Not everyone needs O2. Can inform nurses of target sats - may be CO2 retainers and only need 88-92%

method of O2 delivery
flow rate / FiO2

Question 8

what are the different methods for O2 delivery..

Answer 8

can categorise in level of O2 requirement
1. nasal specs - up to 4L/min - around 30-40% O2
2. simple face mask - 10L/min - up to 60%
3. non-rebreathe - 15L/min - doesnt get 100% O2 and variable due to entrainment at high peak insp flow- maybe up to 90%
4. venturi - up to 60%
5. high flow nasal canula - 100%
6. . Non invasive - CPAP/ BiPAP - CPAP usually for Oxygenation / pulmonary oedema, BiPAP for ventilation e.g. COPD
7. Invasive ventilation - various modes.

Question 9

who is it important to avoid high O2 in?

Answer 9

anyone - O2 is toxic - ROS form. dont need to have excessive amounts.

however specifically COPD - CO2 retention removes hypoxic drives to respiration and may worsen V:Q mismatch

pre-term infants - risk of retinopathy from ROS

Question 10

effect of digoxin on cardiac and pacemaker potential?

Answer 10

pacemaker - vagal effect reduces phase 4. reduces phase 0 because more ca in cell (less gradient)

cardiac cell - higher resting potential (more Na in cell). hence mroe excitable