osce stuff , anatomy, positioning Flashcards
which artery is most likely responsible for extradural haematoma? what do they look like and why?
middle meningeal
found at pterion - junction between temporal, parital and ethmoid
extradural haematomas arise between dura and skul and are bounded by attachment sites of dura and skull hence give a classic concave shape.
ich
what type of vessel and patient group is a subdural haematoma seen in?
venous - slow bleed
elderly, chronic alcohol , coagulopathies
What are the indications for jugular venous cannulation …
Medications - norad, high concentration pottasium , long term abx
Difficult access
Measurement of CVP , CO monitoring and swan ganz
Measurement of venous saturations and paO2
which type of brain bleed, classically presents with a lucid period?
extra dural
where are subdural haematomas found
between dura and arachnoid
limited by the one side of brain by falx cerebri
cresent shape
how would a chronic subdural appear on CT?
less bright, darker area of bleed.
which 3 views of C spine are needed to assess?
Lateral view - should be able to see all 7 vertebrae
Anteroposterior view
Open mouth odontoid view - good for diagnosing fracture or lateral displacement of odontoid process
how is a C spine Xray systematically reviews?
allignment:
a line should pass through anterior vertebral bodies
a line should pass through anterior and posterior aspect spinal canal
a line passing through the tips of spinous process
bony
assess height of the bodies
contours
pedicles
transverse and spinous processes
cartilages - invertebral disc space.Vertebral malalignment of more than 3mm suggests vertebral dislocation.
what is the normal space between anterior arch of atlas and odontoid process
less than 3mm
what should be considered when optimising patients positon
patient
* avoid nerve injuries
* avoid dislogment of ET tube
surgery
* correct positon for surgery - may need to be a compromise
access for anaesthetist e.g. IV cannula, NMBA monitoring
what patients are most at risk of poor positioning?
elderly - less mobile joints, poor skin integrity, less fat to pad nerves
obesity - more likely to be difficult to position and therefore may lead to poor positoning
diabetic - poor skin
arthritis
what are the factors that can result in positional harm
tourniquets
abnormal positons e.g. prone, head down (cerebral oedema)
long operations
anaesthesia - patient cant feedback
what are the mechanism of nerve injury from poor positoning ?
compression
ischaemia
direct truama - cutting
tension - stretch
what are the different types of nerve injury ?
Neuropraxia - mild tempory from compression
axonetmesis - axon damaged but epineurium and perineureum intact. wallerian regeneration 1-2mm/day
neuronetmesis - complete sethering, hard to recover from
consequence of ulnar nerve damage
loss of sensation medial 1 1/2 fingers palmer and dorsal surface
motor - finger abduction and adduction, adduction of the thumb. hypothenar weakness (little finger)
what are the anaesthetic consequences of laparoscopic surgery
A: dislogement of tube - endobronchial intubation. LMA doesnt sit well - should avoid LMA. increased risk of aspiration due to raised gastric pressures
B: reduced FRC, closing volume may now exceed FRC, atlectasis and shunting, hypoxaemia. can add PEEP to overcome. increased airway pressures, risk of barotrauma.
CO2 absorption - respiratory acidosis
C: increased thoracic pressures, reduce preload and hence CO.
increased PVR
D: raised ICP, can get cerebral oedema
E: poor renal perfusion due to low CO, AKI, poor clearance of drugs
G: poor GI and liver perfusion - affects metabolism of anaesthetic drugs. increased N&V
what are the contraindications to laparoscopic surgery?
known raised ICP
haemodynamic instabilty
patent FO - increased PVR and pressure on right side may reverse shunt.
how can patient injury be minimised in surgery
secure to table
use padding
tape eyes closed
tourniquet timer
awareness of positoning e.g. how long been in trendelburg - have a break
what is well leg compartment syndrome?
if a leg is raised
there is reduced perfusion especially in pneumoperitoneum
can mimic compartment syndrome
more likely in long operation, large muscle mass, hypotension.
can flatten every 2 hours to re-establish circulation
Which drugs have to be given via central line?
NORAD , vasopressin
Chemotherapy drugs
High conc pottasium
TPN
In what situations may a DINIMAP be inaccurate ?
Incorrect cuff size
Arrhythmias
Movement
External pressure
How are risks to patient having laser airway surgery minimised
Low FiO2
Special ET non flammable tube
Double cuff
Filled with saline or methyl blue dye
Non reflective Matt surgical instruments
How are risks to patient having laser airway surgery minimised
Low FiO2
Special ET non flammable tube
Double cuff
Filled with saline or methyl blue dye
Non reflective Matt surgical instruments
What is the definition of ultrasound?
Sound waves above the frequency of human hearing (>20kHz)
What frequency of ultrasound is used in medical ultrasound
5 MHz (ultrasound is 20KHz )
What is the piezoelectric effect ?
The phenomenon whereby piezoelectric crystals are able to convert current of a specific frequency into sound waves of a corresponding frequency and vice versa. It occurs because current will cause crystals to vibrate and emit sound waves
What is the name of these probes , give examples of when they are used
Linear probe - e.g for nerve blocks - brachial plexus
Curved linear to do a spinal in obese patient and view the ligamentum flavum
Phased array probe - subcostal imaging of the heart
what is this..
von recklinghaus oscilonometer
(2 wires)
what is this..
sphygomomanometer
s fig mo man o meter
what is this
DINAMAP
device for indirected non invasive automated MAP monitoring
what are the causes of ultrasound signal attenuation?
Ultrasound signal attenuation refers to the reduction in the strength (amplitude) of an ultrasound wave as it travels through tissue or other media
absorption of waves by tissue
reflection and scattering of waves
divergence and refraction of sound waves as they pass through tissues.
what can an erector spinae block be used for? what is an alternative block?
rib fractures, breast surgery
paraspinal block is an alternative as more likely to get ventral rami - more effective but riskier - treated like neuroaxial e.g. cant do if on anti-coagulants.
(the ventral rami go all the way around to the front and cover sensory up to sternum, dorsal rami only cover the back area)
where do you inject in an interscalene block?
between C5 and C6
what other nerves can be found near middle scalene in a interscalene block?
long thoracic
dorsal scapular
(could damage these when needling)
Reasons for needing a tracheostomy?
weaning on ITU
upper airway surgery - inserted by ENT
someone cant clear secretions - risk of aspiration
What is the RAS score used on ITU?
Richmond agitation sedation scale
from +4 to -5
normal is 0
+4 - very aroused e.g. fighting
-5 - very sedated / unarousable
What are the reasons for tracheostomy weaning on ITU?
Can reduce sedation - assess neurology better, able to get back to more normality
passy mure valve and talking
mouth hygeine
what is the difference between surgical and percutaneous trachy
surgical tracheostomies are usually in more complex cases - improtant to know when assessing as this can tell you if this is a complex case.
infection rates much higher with surgical.
at what level is tracheostomy inserted?
usually between 2nd and 3rd tracheal ring
how do you descibe a tracheostomy tube..
size - internal diameter
cuffed/ uncuffed
fenestrated?
inner tube?
adjustable length?
what is this..
passy muir valve
inspiration allowed but valve shuts on expiration, expired air diverted to upper airway for phonation
MUST have cuff down!
what are the complications of tracheostomies?
immediate - bleeding, failure, ventilation issues, reactions to drugs given (roc, proporfol), damage to posterior tracheal wall
early - secretions blocking tube, dislodged tube
later - innonimate artery erosion and bleed, infections
how long can a percutaneous trachy be left in?
30 days
in an emergency for someone with a trachy, what 2 things can be found at the bedside?
blue box - trachy equiptment e.g. paeds face mask , suction catheter
trachy algorithm
what spinal levels mediate pain in labour?
T10 to L1 - contractions
S3 to S5 - delivery
how common are some of the complications of epidurals..
NAP3
Failure to work- 1 in 20
Hypotension - 1 in 50
Headache - 1 in 150
Nerve damage - temporary 1 in 2000, permanent 1 in 15000
paralysis 1 in 250,000
risk of meningitis also rare
for spinal anaesthesia in C section, what level do you want to block up till?
T4 - nipple line
describe the mallampati scoring system..
scored from 1 to 4 depending on view of oropharynx. correlated with ease of intubation
1 = PUSH - tonsillar Pillar, uvula, soft palate, hard palate
2 = USH = uvula, soft palate, hard
3 - SH = soft and hard
4- H = hard palate only
class 3 and 4 - should suggest difficult intubation
what is the thyromental distance?
tip of thyroid cartilage to tip of chin
should be more than 6cm, less than this makes laryngoscopy hard
what sternomental distance suggests difficult laryngoscopy?
less than 12.5cm
what scoring systems do you know to test difficulty of intubation..
mallampati
thyromental and sternomental distance
wilson score - takes into account BMI, head and neck movement, jaw movmeent , receeding mandible and buck teeth - each scored on a three-point
scale (0-2). A total score of 2 or more is associated with an increased incidence of difficult intubation
how is a mallampati performed?
patient sits opposite the anaesthetist with their head in a neutral position,
the mouth open as wide as possible and the tongue protruded maximally
what are the predictors of difficult mask ventilation?
BMI >25
age >55
beard
dentures
history of OSA
facial abnormalites
clinical signs of tension pneumothorax
dyspnoea / respiratory distress
low sats
hypotension
tachycardia
why may stridor develop post thyroid surgery?
tracheal compression from haematoma
vocal cord paralysis - recurrent laryngeal nerve palsy
why may a patient become breathless post subclavian central line insertion?
higher risk of pneumothorax or haemothorax
what is a normal JVP?
less than 4cm above manubrium when sat at 45 degrees
how are murmurs attenuated?
aortic - sit patient up , hold in expiration , over aortic area
mitral - roll onto left, listen in mitral area, hold in expiration.
clinical signs of aortic stenosis..
hx - syncope, chest pain , breathlessness
clinical signs - narrow pulse pressure, ejection systolic murmur radiating to carotids, slow rising pulse
how is muscle power graded?
what can character of a pulse indicate?
thready - weak pulse , difficult to palpate - hypovolaemia, heart failure, cardiogenic shock, peripheral arterial disease
bounding - a large volume with forceful upstroke - early sepsis, hyperthyroid, aortic regurgitation
slow rising - slow upstroke and low amplitude e.g. aortic stenosis
pulsus alternans - AF - varying strength
how do you measure JVP?
Determine the upper level of the JVP and measure the vertical distance between this point and the sternal angle.
normally around 3cm which equates to 8cmH20
how do you distinguish carotid pulse and jugular pulse?
carotid is palpable
JVP colapses on palpation
however JVP better seen
JVP - double waveform
also hepatojugular reflux - increases JVP
course of JVP
earlobe
between 2 heads of SCM
to middle third of clavicle
how would you do a pre-op assessment in a smoker?
history - pack years, any CVS or resp disease , check for symptoms - persistent cough, breathless, chest pain
resp and CVS examination
IX - CXR , pulmonary function tests i.e. spirometry , ABG, ECG
what are the C spine indicators of difficult intubation …
Reduced neck mobility- reduced atlanto-occipital extension
narrowing of prevertebral space - swellings
osteophytes
kyphosis / scoliosis
Traumatic changes like fractures, subluxations,
what does the swining of a chest drain indicate?
correct position
fluid level is moving as patient breathes in and out creating negative intrapleural pressures etc.
patency of the drain - can tell you if it suddenly gets blocked.
During inspiration, the negative pressure in the pleural cavity increases, leading to increased flow of air or fluid into the pleural space through the drain. This causes the level of fluid in the drain’s collection chamber to rise. expiration, level drops
what does rinnes and webers demonstrate?
Rinnes test
Strike a 512 Hz tuning fork
Place on left mastoid process until sound disappears
Then hold in front of same ear, sound should be heard again because air conducts > bone
If sound is better through bone = conductive hearing loss
Webers
Same tuning fork, now on midline of forehead
Sound should be equal on both sides.
Conductive hearing loss = sound will localise to bad side - less interference from surrounding.
Sensorineural hearing loss = sound better on good side
what is the difference between a dermatome and peripheral cutenous nerve territory?
cutaneous nerve distribution – area of skin innervated by single peripheral nerve
dermatomal nerve distribution – area of skin supplied predominantly by a single spinal nerve.
what are the 3 techniques for regional?
Landmark
Nerve stimulator
Uss
what does PREP - STOP- BLOCK involve?
safety check list before any regional technique
Prep = drugs, position, clean
Stop = check consent / site – i.e. stop before block
Block
what do the following terms in USS mean? depth, gain, focus, anisotrophy
Depth
Gain – amplification of returning signal – makes image more white
Focus – optimises lateral resolution
Anisotropy – angle of ionisation
This is how well a nerve respond to USS and is optimised when probe is 90 degrees to nerve. If the nerve is curved the probe angle needs to be altered as it tracts the nerve down.
what is this..
water circuit
what is this
bain circuit
what is this…
magils circuit
what checks would you do before transfering a ventilated patient..
I would look up the local trust transfer check list…
- O2 cylinder - full and back up available
- emergency drugs available
- ongoing sedation - enough propofol
- back up ventilation device - water circuit and face mask
- emergency airway equiptment - laryngscope, guedel, LMA
- portable suction
- sufficient personale
- monitoring and capnography
- A to E
What is this device
Fuel cell - measures 02
What is this device
Fuel cell - measures 02
What is this device
Pulsed field paramagnetic O2 device
A = differential pressure transducer
B = rapidly alternating magnetic field
what are the indications for using a throat pack?
stops blood entering the stomach in ENT / max fax surgery. blood is emetogenic
stabilising ET tube when patient is in prone position.
name the parts..
A = bevel
B = murpheys eye
C = cuff
D= vocal cord guide
E = internal diameter mark
F = 15mm connector
G = spring loaded one way valve
H = pilot balloon
markers for how far deep.
what is the difference between wide bore and small bore chest drain?
small-bore drains are advantageous for less invasive procedures and smaller fluid collections. seldinger technique
, while large-bore drains are necessary for more significant or urgent drainage needs. larger incision, more painful, more infection risk.
what are the two methods of chest drains…
water seal drainage - not an active process, air is pushed out during expiration
dry suction drainage - one way valve and applies suction effect
what rates do high flow O2 devices work at?
up to 60L/min
what is this..
CPAP machine
uses pressures - 5,10,12 and 15 cmH20
in invasive ventilation what variables increase oxygenation vs ventilation?
MV - ventilation and CO2 levels
areas for gas exchange and less shunting = oxygenation hence adding PEEP
when using a 15L non rebreathe mask will 100% O2 be delivered?
no , peak inspiratory flow rates are much higher and will entrain air from sides of mask.
venturi devices - are fixed O2 devices and have higher flows
what are the 2 main categories of indications for invasive ventilation
AIRWAY - e.g. low GCS, burns, epiglottitis , vomitting
BREATHING e.g. improve oxygenation / remove CO2, no resp effort (opioids)
how does APRV work?
airway pressure release ventilation
keeping airway pressures at 30cmH20
opens up small alveoli, less atelectotrauama from opening and closing, improves oxygenation
however less ventilation - just small period of releasing this to blow off CO2
what is a precordal thump?
if no defib immediately available
can hit chest with fist
if witnessed arrest, how is it managed?
if pads already on 3 successive shocks can be given and look for rosc.
start CPR if 3rd shock unsuccessful
how far should O2 be kept away in shock during defib
1 meter
what is meant by the chain of survival?
systematic approach to improve survival chances
early recognition - NEWS
early CPR
early defib
good post resus care
how is the airway managed in a cardiac arrest
initially bag valve mask device 2 person technique
aim to get an LMA or tube in with capnography
can an LMA be used in an arrest over a tube?
yes if ventilating well and low aspiration risk. however ET tube will protect airway better
more risk of gastric inflation with I gel - this will extend stomach, can split diaphragm and increase risk of vomitting.
what are the uses of capnography in an arrest?
gives info on quality of ventilation and chest compression
gives indication of ROSC and return of circulation
what is the post cardiac arrest syndrome?
hypoxic brain injury
myocardial dysfunction - usually recovers in 3 days. manifests as low CO and arrhtyhmias
systemic ischaemic repurfusion response - activation of immune and coaf pathways - can result in multiorgan failure
what temp and glucose may be seen post arrest and what is this associated with?
hyperthermia and hyperglycaemia - correlated with poor neuro outcome
what is the role of sedation post cardiac arrest?
reduces O2 consumption
allows for intubation and controlled ventilation
allows more controlled state to help return to homeostasis
when is prognostication post arrest reliable
72 hours
how is death post arrest diagnosed?
leader makes a call on if appropriate to continue or not.
no central pulse
no heart sounds
asystole on ECG or ECHO showing no contraction or no pulsatile activity on arterial line.
observe for 5mins
which rhythms have worse outcome
non-shockable
what are the signs of a basal skull fracture?
rhinorrhoea, ottorhea
bruising under both eyes and behind ears
what is a flail chest?
rib broken in 2 or more places . such that there is a floating segment.
significance - pain on ventilation, shallow breaths and V:Q mismatch, inadequate cough
what is MILS?
manual in line stabilisation
with hands before collar/ block
methods of assessing consciousness..
GCS
AVPU
mini mental state exam
richmond agitation sedation scale
which induction agent could you use to anaesthetise trauma patient?
thio - quicker RSI, neuroprotective - reduces O2 consumption
what are the different huber tips on an epidural?
this is the type of needle tip - It is blunt and curved (non-cutting), designed to separate the tissues rather than cut through them
what is the name of the markings on an epidural needle?
lee’s lines
how long is a standard epidural needle
9cm
what is the role of the stylet in an epidural needle?
The stylet is a solid, metal wire inserted inside the hollow needle before insertion. It helps the needle maintain its shape and prevent any tissue from clogging the needle’s lumen during advancement.
what is meant by gauge and french when describing needle size?
both units of measure of diameter
gauge = 1 guage is 44mm, the number of wires that can fit into 1 gauge gives you the size e.g. higher the number the smaller the canula
1 french = 1/3 mm in diameter
what is the pH electrode also known as?
Sanz electrode
what levels need to be blcoked for C section? vs 1st and 2nd stage of labour
T4 to S1- C section
1st stage of labour = T10 to L1
2nd stage (delivery)= S3-S5
what would you see on CXR if phrenic nerve paralysed on one side
raised hemidiaphragm
reduced lung vol on that side
what is the boyles davis gag? (needed to know this for exam)
thing to keep mouth open in ENT surg e.g. tonsillectomy
ensure it doesnt obstruct the ET tube and ventilation
what factors increase success with DC cardioversion?
good pad placement
correction of electrolytes
AF < 48hrs responds better
synchronised shock
young patients better
what is the specificity and sensitivity of mallampati and most airway test
mallampati - good specificity but poor sensitivity i.e. can be more sure someone is a difficult intubation than someone is a easy intubation. i.e. mallampati 1 could still be bad.
what is risk of a pharyngeal pouch for anaesthesia?
risk of reflux - contains food
also risk of mechanical airway obstruction from pouch
may distort anatomy and make intubation difficult
pre op - thorough hx and fasting times. pre op imaging - barium swallow (size and location)
could be emptied - gentle suction under guidance
RSI or awake fibreoptic - head up position, ET tube
signs of orbital blow out fracture..
proptosis (exopthalmos) or enopthalmos
sweling / bruising
diplopia
Numbness or decreased sensation over the distribution of the infraorbital nerve
limited eye movement
pain
CT face - is gold standard
what does the infraorbital nerve do?
branch of maxillary nerve of trigememinal
upper lip, cheeks , nasal cavity, lower lid
what can SSRIs do to bleeding risk?
increase it
serotonin plays a role in hemostasis
what is the post exposure prophylaxis for HIV (prev question)
start within 72 hours
consult occupational health
28 days of ART
testing for HIV at the time, 6 weeks, 12 weks, 6 month
what is the post exposure prophylaxis for hepatitis C
no prophylaxis
just need to test at regular intervals
then can start treatment
likelihood of transmission post needle stick injury
HIV = 0.3% if source is positive
hep C = 2%
hep B = higher
how would you detect a misconnection in a breathing circuit?
visually see the disconnection
loss of capnography
machine alarms - ventilator disconnection alarm
what are the settings for a ventilator disconnection alarm?
low tidal volume
low pressure
what factors increase the difficulty of airway management in truama patients?
normal stuff - beard, anatomy
swelling and bleeding
facial fractures and abnormal anatomy
risk of aspitation
Manual inline stability - keeping neck straight cant manipitlate
mechanical trismus
what forms of shock may be seen in trauma patients?
hypovolaemic
cardiogenic - tamponade
spinal e.g. neurogenic
what strength of adrenaline is given in cardiac arrest?
10ml
1 in 10, 0000
how much adrenaline is in 1 in 1000
1mg in 1ml
how much adrenaline in anaphylaxis?
0.5mg
as 0.5ml of 1 in 1000 usually
what is the threshold for which O2 doesnt work in shunts (previously asked)
if a 30% shunt of more, increase in FiO2 doesnt not have much effect
what categories of C section are there?
Cat 1 -immediate threat to life, delivery within 30 mins e.g. fetal distress, uterine rupture, placental abruption
cat 2 - maternal / fetal compromise, delivery within 60-75 mins e.g. failure of instrumental delivery, fetal heart rate non reassuring
cat 3 - no immediate risk but early delivery indicated e.g. within hours, e.g. failed induction
cat 4 - planned elective e.g. prev C section, twins
management of a bleed post tonsillectomy?
assess patient
A to E - IV , X match
bleeding profuse or just oozing
sit them up to prevent aspiration
surgeons
consider TXA
how is a fibreoptic scope sterilised?
cant be autoclaved due to sensitive material and damage including electronics
cleaned chemically - ethylene glycol
explain the design of an ambubag?
mushroom valve - one way valve , when bag compressed air flows into patient. when patient expired the expired gases are vented and do not re enter the bag
small dead space within valve and mask
silcone bag that returns to originate shape
what are the options when puncturing during with epidural?
keep it in the spinal space - smaller doses, only by anaesthetist
resite the catheter - risk of LA going through the dural puncture into the spinal space - only should be used by anaesthetist
managing status
on side
call for help
15L
A to E
continuous monitoring
IV access
Lorazepam 4mg IV
keppra infusion / phenytoin
RSI - thop
D - glucose and temp
managing anaphylaxis intra op
stop infusion
100% O2
call for help
red box with IM / minijet of adrenaline
give 50ug of adrenaline IV
fluids, bronchodilator (sevo, magnesium, salbutamol)
legs up.
hydrocortisone 200mg , chloramphenanime 10mg
HDU - biphasic
mast cell tryptase within 1 hour after 24 hrs
how is adrenaline prepared for IV in anaphylaxis?
take 1ml of 1 in 10,000 minijet and dilute in 10ml
now every ml is 10ug
give 5ml in anaphylaxis
in paeds give 0.1ml/kg
complications of long term steroids to surgery?
addisonian crisis
also to consider higher risk of infection, osteoporosis, risk of diabetes, poorer wound healing.
