prescribing Flashcards
which abx work by binding to cell wall and inhibiting cell wall synthesis
beta lactams: penicillins and cephalosporins and carbapenems
glycopeptides also active against penicillin binding proteins
which abx work by inhibiting nucleic acid synthesis or function
metronidazole and rifampicin
which abx work by inhibiting DNA gyrase
fluroquinolones
which abx work by inhibiting ribosomal acitvity and protein synthesis
aminoglycosides, tetracyclines, lincosamides, macrolides, chloramphenicol
which abx wotk by inhibiting folate synthesis and carbon unit metabolism
sulphonamides and trimethoprim
baceriostatic
prevent growth of bacteria
abx that inhibit protein synthesis or DNA repication or metabolism
need a minimum inhibitory concentration
bactericidal
kills bacteria
abx that inhibit cell wall synthesis
needs a minimum bactericidal concentration
how to bacteria become resistant to abx
change abx target
destroy or inactivate abx with an enzyme-beta lactamase, penicillinase
prevent abx access-changing channel
remove abx from bacteria-using pump
how are bacteria abx resistance
intrinsic: equally resistant in population
acquired: spontaneous gene mutation, horizontal gene transfer( conjugation, transduction, transformation)
important gram positive resistant organisms
MRSA: staph aureus resistant to beta lactams and methicillin
VRE: enterococci resistant to vancomycin
important gram negative resistant organisms
ESBL: extended spectrum beta lactamase
AMpC beta lactamase resistance: broad spectrum penicilllin ,cephalosporin and monobactam resistnce
what to use for resistant gram negative bacteria
carbapenems
however also becoming resistant
what are beta lactams
penicillins, cephalosporins, carbapenems,
which bacteria have a bigger cell wall
gram positive
common causes skin infections
staph aureus, group a strep
common causes chest infections
strep pneumoniae
common cause throat infections
group a strep
common causes urine infection
e.coli, klebsiella sp, proteus sp
common causes gallbladder infections
e.coli, klebsiella sp, proteus sp
common causes abdo infections
e.coli, klebsiella sp, proteus sp
common causes infective diarrhoea
shigella, salmonella
why do beta lacatms work against gram positibe
target cell wall, gram positive have thick cell wall
when are vancomycin and teicoplanin useful
gram positive
MRSA
penicillin allergy
give e.g. macrolides
clarithromycin and erythromycin
what are macrolides used for
gram positives and atypical pneumonia (legionella, mycoplasma)
give e.g. lincosamides
clindamycin
use of lincosamides
gram positives-s.aureus, GAS, anaerobes
cellulitis if penicillin allergy
necrotising fascitis-as turns off toxins made by gram posive bugs
give e.g. tetracyclines
doxycycline
use doxycycline
broad spectrum but mainly gram positibe
cellulitis if penicillin allergy
chest infections
use of ciprofloxacin
gram negative > gram positibe
UTIs, gallbladder infections, abdo infections
uses of trimethoprim
broad spectrum but mainly gram negatives
UTIs
uses nitrofurantoin
gram negatives
UTIs
what beta lactams can be used for gram negatives
amoxicillin-clavulanate
piperacillin-tazobactam
meropenem
cefuroxime
ceftriaxone
cefotaxime
done first 4 recorded lectures (antivirals not useful)
difference between inhaler and nebuliser
inhaler=powder
nebuliser=aerosol
categories of bronchodilators
adrenergic (sympathetic)=cause bronchodilation
anti-cholinergic (parasympathetic)=block bronchoconstriction
how do B2 adrenoreceptor agomists work
cause smooth muscle relaxation and bronchodilation
inhibit histamine release from lung mast cells
saba
salbutamol
laba
salmeterol, formoterol
how do muscarinic receptor antagonists work
block muscarinic receptors on airway smooth muscle, glands and nerves to prevent muscle contraction, gland secretion and enhance NT release
e.g. muscarinic receptor antagonists
atropine
ipatropium bromide
what effect do glucocorticoids have on airway
anti-inflammatory
suppress production chemotactic mediators
reduce adhesion molecule expression
inhibit inflammatory cell survival
ICS e.g.
beclomethasone dipropionate
budesonide
ciclesonide
mometasone furoate
side effects ICS
loss of bone density
adrenal suppression
catacacts, glaucoma
ASA grading
1-normal healthy
2-mild systemic disease
3-severe systemic disease
4-severe systemic disease, constant threat to life
5-moribund patient, not expected to survive over 24 hrs with/without surgery
6-declared brain dead, organ retrieval
ADD E IN EMERGENCY
Pre-optimisation before theatre
bp monitoring
urinary catheter
central venous access
inotropic support
CO monitoring
maximise o2 delivery to supranormal levels
premedication before theatre
analgesia, sedatives, antiemetics, antacids
drugs omitted pre-op for elective surgery
ACEi 24-72h
angiotensin receptor anatgonists 24-72h
anti tnf 2w
platelet i 7-10d
doacs 3-4d
nsaids mechanism of action
inhibit cox enzyme
therefore reduce prostaglandins, prostacyclin and thromboxanes
nsaids adverse effects
gastric (peptic ulceration), coag, resp (can precipitate severe asthma), renal (can cause renal failure if bleeding or bp low), cardiac
COX1
constitutive form
present in tissues
inhibition leads to gi se
cox2
inducible form
present at sites of inflammation
inhibition probably responsible for anti inflammatory properties of nsaids
cox 2 inhibitor
parecoxib-dynastat
when to avoid nsaids
renal impairment
hyperkalaemia
hypovolaemia
circulatory failure
severe liver dysfunction
cardiac disease, MI, CVA
when to use nsaids with caution
> 65
dm
arteriopathy
cardiac/hepatobilliary/major vascular surgery
orthopaedics 48hr post op
intraoperative drugs
oxygen
fluids
blood products
abx
anaesthesia
anagesia
muscle relaxants
anaesthetic agents
inhalational most common
IV often used for induction
desflurane
inhalational-fluorinated hydrocarbon
v bad for environment
rapid recovery
possible reduction in post op cognitive dysfunt
TIVA
total intravenous anaesthesia
no bad greenhosue gas effects
muscle relaxation for anaethesia types
depolarising (non-competative)-suxamethonium
non-depolarising (competative)-rocuronium, atracurium
sugammadex
reversal of neuromuscular block due to rocuronium or vecuronium
rescue reversal dose 16mg/kg
time 1.5 mins
only use in emergency
post op drugs
analgesia
fluids
blood products
inotropes/vasopressors
anti-emetics, anti-coag, abx
regional anaesthesia for pain
regional blocks
epidural: local anaesthetic +/- opioid, continuous infusion
what weight should fluids be based on
IBW (M=H in cm-88, F+ h in cm - 92
blood vol in adults
70ml/kg
blood vol children
80ml/kg
blood vol neonates
90ml/kg
constituents of ECF
more sodium
Na=140, K=4, Ca=2, Mg=1, Cl=105
constituents ICF
more potassium
Na=10, K=150, Ca=3, Mg=30, Cl=3
colloids
large molecules in liquid medium e.g. blood, albumin
crystalloids
salty water e.g. saline, hartmanns, 5% desxtrose
water requied per kg
25-30ml
Na required per kg
1-2mmols
K required per kg
1 mmols
energy required per kg
30kcal
glucose required to prevent ketoacidosis
50-100g per day
loss of fluid
sensibble=visible
insensible=not e.g. sweat, 3rd spacing
signs severe dehydration
2+: lethargy, loc, sunken eyes, poor or cant drink, skin trugor >2s
obs suggesting fluid resus
BP<100, HR>90, CRT>2s, cold peripheries, RR>20, NEWS >/=5, leg lifting
principles of fluid resus
calculate deficit
ongoing requirements
monitor results
USE FLOW CHART ON FLUID CHART
check before prescribign paracetamol
liver impairment
severe cachexia (<50kg max 500mg qds)
check before nsaids
renal and platelet count
CI: GI bleeding, ulcer hx, asthma
other meds: warfarin, digoxin, steroids
bioavailability IV infusions
approx 100%
vancomicin infusion
500mg in 100mls normal saline over 2hrs
amiodarone infusion
in emergency: 300mg in 100mls over 30 mins
once stable 900mg over 24hrs
propofol infusion
total IV anaesthesia
monitor depth using EEG
heparin infusion
emergency anticoag
1000 international units per ml, 3000 units usually enough for 24h
noradrenaline infusion
septic shock
4/8/16mg in 50ml via central line at 0.01-1 microgram/kg/min
patient controlled morphine infusion
50mg morphine in 50mls
bolus 1mg, 5 min lockout, max 12mg/hr
