book and course Flashcards
which infusion in critically ill is most likely to cause hyperglycaemia?
adrenaline
Also raised lactate
what has a faster clearance alfentanil or fentanyl? and elimination half life?
fentanyl
the elimination half life of alfentanils is shorter despite having a slower clearance rate.
this is because its Vd is smaller than fentanyl
whats the armitage rule for caudal anaesthesia in paeds?
bupivacaine 0.25%
0.5 ml kg 1 for sacro-lumbar block,
1 ml kg 1 for abdominal block,
1.2 ml kg 1 for mid-thoracic block
what is the bowman principle?
low potency, more drug, quicker onset
what are the properties of a drug that can be used to measure gastric emptying? example?
100% Bio oral availability
zero stomach absorption
rapid GI absorption
paracetamol - well and rapidly absorbed from small inttestine
how is renal clearance calculated?
[U]x V / [P]
check units
what is the best measure of LV contractility?
LV ejection fraction
during exercise what has the biggest influence on increased O2 delivery?
relaxation of pre capillary sphincters - 20 to 30 fold in skeletal blood flow
(cardiac output is only 5-10 fold)
what is the most important factor contributing to increased oxygen delivery in pregancy?
increased venous return (due to increased vasodilation (progesterone) and increased circulatory volume (oestrogen)
leads to increased CO
in giant squid axon what make resting membrane potential less negative?
permeable only to potassium
using nernst
if you increase outside conc of potassium this will make it more similar to inside - hence less negative .
overall increase K OUTSIDE
how is SVR calculated?
SVR = k x (MAP-CVP)/CO
how is O2 conc of venturi mask calculated of entrainment ratio 1:10?
1:10 = 1 of 100%, 9 parts 21%
if 6L/min this will be increased to 60 L by the entrainment
6L = pure
60L = 21%
(6x1.0) + (60x0.21)
when increasing depth on USS, what happens to wave to optimise image?
longer wavelength, lower frequency
can penetrate to a greater depth
why cant n20 cylinder gauge pressure be read as a measure of contents?
the pressure gauge will read SVP at ambient temp regardless of cylinder contents
if CO2 baseline is raised on anaesthetic machine, what is the most immediate action?
increase fresh gas flow - get rid of CO2 and prevent rebreathing
(then replace soda lime)
what is the most important safety feature of electrical equipment connected to patients in theatre?
avoidance of earth leakage currents
what type of damping is best for real time accuracy?
optimal damping = greatest real time accuracy
which part of arterial waveform is the best indicator of ventricular contractility?
the slope of the upstroke
how does LV compare to RV?
LV much thicker and circular
RV cresent shaped
when LV contracts, it bulges and reduces efficiency of RV.
what is the relative density of helium and xenon compared to air (1)
helium = 0.14
xenon = 4.5
For succinylcholine when can it be used safely in burns? whats the best agent for RSI
Succinylcholine is safe for the first 24h after thermal injury.
best agent for RSI when needing rapid trachea intubation due to full stomach
equation for kinetic energy?
KE = 1/2 m x v2
equation for potential energy?
E = Mgh
m=mass
g = gravity = 9.81
height = m
equation for electical energy?
current x volts x seconds
Watts x time
Coulomb x volts
1/2 capacitance x V2
what type of antibiotic is clarithromycin?
how do these work?
macrolide
inhibit 50S
how much conc of drug in plasma after 2 mins - what do you need to calculate and how?
clearance = vd x k
gives you litre/min
times this by number of mins
e.g. 2x clearance
remove this value from the Vd
work out new conc with new Vd
OR
if k=0.1min-1 = 10% of conc removed from drug
so X x 0.9 = Y
again in second minute
Y x 0.9 = answer
