Pre-operative assessment Flashcards
who needs a pre-op assessment
o All need some form – differs how much
o Elective – GA, regional anaesthetics all pts
o LA – select pts – do need to be assessed because might need crash emergency GA
o Emergency – all
who does the pre-op assessment
o Initial assessment – nurse specialist led, surgical junior
o Secondary assessment if required if concerned about fitness or something flagged up – booked into anaesthetics pre-op assessment – anaesthetist
what is the purpose of the pre-op assessment
Identify risk – Airway – Anaesthetic – (Surgery - this should already have occurred) – Post-operative – May require further special tests • Modify risk – May require interventions pre-op • Make decisions on medication – Eg aspirin / metformin • Give advice on fasting individualised decisions on type of anaesthesia/analgesia taking into accounts risks benefits and wishes predict difficult airway • Make decisions on post-op care – Eg ICU / HDU o Explain to pt what to expect with stay and anaesthetics – can be done with surgeons assess need for thromboprophylaxis make sure right surgery optimise before surgery get consent, alleviate worry ie Pre-op assessment identifies problems, should be addressed, on the day they reassess and check airway and meds again and decide what med they will use
is info about surgery involved in pre-op assessment
no
o Pts should already have been seen in a surgical clinic, and talked about surgical team about complications – can be difficult to take in all info, so may need reiteration – but if too many qns – need to be redirected
when is the pre-op assessment done
After surgical clinic and decision to operate
• 2-4 weeks before surgery
– Long enough to arrange further investigations
– Soon enough to avoid interim medical problems
how is the pre-op assessment done
Pre-COVID19 – in person • Now – Initial assessment • Telephone / video – Attendance as required for • F2F review • Bloods • ECG • MRSA swab • Special tests eg echo • COVID swab
what is important in a pre-op history
Planned procedure – minor / intermediate / major
• Past Medical History
• Previous Surgery / Previous Anaesthetics
– Ask ‘any problems with previous anaesthetics’
systems review
med
allergies
social
Fx
BMI
can they lie down
what are possible problems with previous anaesthetics
airway/intubation problems, reaction to drugs, nausea/vomiting (‘PONV’), malignant hyperpyrexia (rare)
recent GA
what systems do you review in pre-op assessment
resp/cardio/renal/endocrine
Social Hx
Smoking / etoh / recreational drug use
– Support at home / work
Fx
– Ask ‘anyone in your family with a history of problems with anaesthetics’
• Malignant hyperpyrexia / Myasthenia gravis
dystrophia myotonica
porphyria
previous problems with muscle relaxants
cholinesterase problems
sickle cell - test if worried
PMHx
risks and comorbidities in full MI or IHD asthma/COPD hypertension rheumatic fever epilepsy liver/renal disease dental problems neck problems GI reflux or vomiting dm existing illness chronic lung disease arrhythmia murmur pregnant is neck/jaw/teeth stable - intubation risk
Dx
Know absolutely everything, inc over the counter – may have interactions or may cause bleeding etc
allergy
importance of Sx
Smoke = increased chance of chest infection, because of paralysis of cilia – 24hr cessation reduce risk
Alcohol stopped – see if would have withdrawal
Is someone at home if going home straight away, or not because no one home
what is malignant hyperpyrexia
dangerously hyperthermic in response to some volatile anaesthetic agents – dantrolene, ITU, cooling = treatment
what is the ASA score
American Society Anaesthesia
what are the different ASA grades
• I Healthy patient, uncompromised
• II Minor systemic disease
• III Severe systemic disease - limits activity but not incapacitating
• IV Severe systemic disease, constant threat to life
V moribund. not expected to survive 24hr even with op
VI brain dead - organ donor
eg for ASA 2
hypothyroidism, well controlled dm/htn
eg for ASA 3
– uncontrolled dm/htn, end stage renal failure needing dialysis
when would you find ASA 4
o – operate for their ASA to fall, in cardiac theatre – cardiac status is why have operation
ASA if eczema and not on steroids
1
what are the different magnitudes of surgery
minor
intermediate
major
major plus
egs of minor surgery
skin lesion w/o flap
breast abscess
intermediate surgery
inguinal hernia - primary
varicose veins
knee arthroscopy
major surgery
thyroidectomy
colonic resection
joint replacement
adrenalectomy
means need further investigations
major plus
cardiac surgery
what do you do if you can’t classify the surgery
o If don’t know what the surgery involves so you cant classify – ask, may be subtleties that increase the risk
what is involved in examinations
o Anaesthetic rather than surgical assessment
o Obs – HR BP temp sats – any trigger need for further investigations and treatment
o Airway
o CV – rate, rhythm, murmur, pain – full CV exam
o Resp – full resp exam – percussion, palpation and auscultation, can they walk up 2 flights of stairs, how far flat - exercise tolerance
o Abdo – good to know before surgery, but most anaesthetics wont – more aligned with surgical team duties. Even for hernia repair – should be examined on morning of surgery. Pick up issue – hepatosplenomegaly w/o cause – don’t want to do op
o Anything you pick up, have confidence in self that you’ve detected things – request the next tests
what are the 4 things involved in the airway assessment
Neck extension / flexion
Mouth opening
Mallampati
Jaw protrusion
why do you check neck flexion/extension
ask put chin on chest adn head all the way back
see if easily do it w/o stiffness/pain – to intubate needs to be partially extended. If oesteoA = painful extension RA AO instability = dislocation = dangerous – need technique in non-extended position – fibreoptic scope. look at notes, plain C spine XR, speak to rheumatologist
why do you see how wide people can open mouth
If small – difficult to get tube in safely – fibreoptic scope
want 3 of their fingers
why do you do airway assessment
o see how easy it is to insert endotracheal tube
o Some pts will have supraglottic airway (no cuffed tube below cords)
o Still need full assessment – if have problems with IGel – need ET tube – so need to assess
o Have clever ways of putting in tubes when know have difficult airway
ways of intubating a difficult airway
laryngoscope elevate the jaw and move tongue out of the way so ET tube can be inserted behind
o Video – have tv screen – so you and the other person can see down
o Fibreoptic intubation – fibreoptic scope through nose/mouth – identify scope between cords – thread ET tube over the top of that
o Assessment tell you if need to bring in the difficult airway trolly
why do you assess jaw protrusion
get bottom teeth in front of top teeth – laryngoscope into miouth – elevate tongue and jaw forward so soft tissue bought forward to make easier to get the tube in
how do you assess mallampati grading
o Ask open as widely as can – see what structures you can see
what can you see in class 1 mallampati
hard palate
soft
uvula
pillars
class 2
hard palate
soft
uvula
class 3
hard palate
soft
class 4
hard palate
what do you do if there is a problem with any part of the airway assessment
speak to anaesthetist – maybe difficult airway clinic – discuss approach pt would need to cooperate with being awake for fibrooptic insertion
when are special tests done
Routine
– Depend on ASA and magnitude of surgery
• Reactive (to patient history / examination)
when do you do a CXR
when there is an abnormal resp exam
known cardioresp disease, pathology, sx or >65yrs
when do you do exercise tolerance tests
problem with CVS, some major surgery where have exercise tests to see if fit – niche surgery – identify problem and discuss with anaesthetists
when do you do sickle test
not unless possibility of undiagnosed sickle – don’t have to do it
reactive tests and indications - NICE guidance
Bloods - Considering existing medicines
– Blood pressure medications (check U&E) eg frusemide = hypokalaemic – affect safety
– Antiplatelet medications might cause covert blood loss (check FBC)
– Anticoagulants (check FBC/coagulation)
– Diabetes medications (check HbA1c)
– Thyroid medications (check TFT’s)
– Anaemia medications (check FBC)
• Pregnancy Test
– Discuss first with patient - test if unknown and pt consents, make aware of risks to foetus, document discussion
• HbA1c
– Only in known diabetics if no result in last 3 months
• Sickle Cell Test
– Only if family history, and never tested before. If SCD - liase with sickle cell service
Echo
– Murmur
– Symptoms
• Breathlessness
• Syncope
• Pre-syncope
• Chest pain (without previous investigations)
– Signs Of heart failure
– Abnormal ECG
CXR
– History – respiratory disease / symptoms
– Examination – abnormal findings
– Surgery specific
MSU if UTI would change decision
what drugs do you need to be considerate of
Blood thinners • Anticoagulants • Antiplatelets – Diabetic meds • Metformin • Gliclazide • Insulins – Antihypertensives • ACE-I • Beta Blockers - AB - anticonvulsants - contraceptive pill - digoxin - diuretics - eye drops (b blockers get systemically absorbed) HRT levodopa lithium MAOo thyroid protection tricyclics
what does continuation of drugs depend on
blood thinners - surgical bleed risk
dm meds - surgical severity
antiHTN - omit ACE-I, continue B blocker
why stop anticoag/platelets
Anaesthetic plan that has bleed risk – eg epidural – epidural haematoma if abnormal INR
avoid epidural, spinal and regional blocks
Surgical risk – antiplatelet/coag stop – different surgery have diff likelihood of causing bleeding and importance of bleeding if happens – in conjunction with surgical team
Colonic resection – stop warfarin if controlled AF – stop and check INR day surgery. If metallic valve – heparin for cover when stop warfarin
Thyroidectomy – small bleed = swelling – tighter – trachea cant drain -compromise airway = death – therefore surgery cant be on any type of blood thinner – because bleeding unlikely but high price. Not all haematoma cause asphyxiation. No NSAID, no clexane post surgery
why stop antiHTN
ACEi – don’t take on morning surgery – cause instability under GA
B blocker – contribute to anaesthetic stability, if on and stop – more risk, so continue
how long do medications need to be stopped before surgery
depends on half life
– aspirin 5 or 3days before surgery. Clopidogrel irreversibly binds – 7days. Warfarin – stop 3days in advance depending on INR - still need to check INR on day of surgery
surgeries with a high price of bleeding
o Spinal and brain surgery – high price of bleeding – no clexane, antiplatelet, coag or warfarin
how long should you be fasted for
Nil by mouth • 2 hours • Except for 30mls water with tablets – Clear fluids • Up to 2 hours before - if anaesthetist allows – not if delayed gastric emptying or other issues, – Solid food (including milk) • Up to 6 hours before chewing gum - 2hrs
principles for fasting times
o End up being fasted for 12hr – because of time of operation
o Gastric emptying time less than 12hr
o So stop being completely dehydrated and hypoglycaemic – neither good for op
what do you do about starving emergency pt
need operation in shorter time frame
so always manage as if they have a full stomach - avoid food for 6hrs before
special considerations
Diabetes
– ?GKI infusion - variable rate insulin infusion
• Sickle Cell
– Post op CPAP
– ?Pre-op red cell exchange (make sure Hb as high as can be)
• Obstructive sleep apnoea
– Post op CPAP
• Ischaemic heart disease
– Pre-op optimisation - angiogram and catheter to improve heart disease pre-op
• Surgery specific
– Graves’ disease – anti-thyroidals / beta blockade
– Phaeochromocytoma – alpha-blockade
what do you do if you identify you need special considerations
manage in conjunction with specialist teams
dm and surgery
10-15% adult UK population
• higher surgery risks: Higher morbidity, mortality, length of stay
• Need for peri-operative optimization
what do you need to do pre-op for dm
check – Blood pressure – Bloods • Renal function • Blood glucose • HbA1c • Lipids – ECG - risk of occult ischemic heart disease refer to endo if CBG >15mmol/l OR HbA1c > 69mmol/mol
dm insulin med in emergency surgery
variable rate IV insulin infusion (VRIII)
dm insulin management for elective surgery - – Minor “fasting 4 hours or less”
No specific management. = Check CBG 4 x daily (aim 6-10mmol/l)
dm insulin managemnet for elective surgery - Major “fasting 4+ hours
No medication = Check CBG 4 x daily (aim 6-10mmol/l)
• Oral agents and good control = Omit medication
and Check CBG 4 x daily (aim 6-10mmol/l)
• Oral agents and poor control = VRIII
• Insulin = VRIII
how do you calculate variable rate insulin infusion
50 units of soluble insulin human (eg Actrapid) in 50mLs NaCL 0.9% soln (1 unit insulin in 1mL NaCl 0.9%)
the rate of infusion depends what the pts blood glucose is
the emergency surgical pt
Higher morbidity & mortality • Less time for optimization • Simultaneous – Assess – Optimise – Liaise with anaesthesia / medical team eg haem / endo
what do you do with an emergency theatre pt
Starved (confirm timing with seniors and anaesthesia)
• Cannula and IV fluid
• Bloods gas – give O2, replace elecs
• Bloods – FBC, UEC, clotting, G+S / X-match
• ECG
• Think about comorbidities / medications
• CXR?
• ECHO?
what do you do if someone has full stomach
rapid sequence induction of anaesthesia - reduce risk of aspiration because not ventilating the patient for long
what is POSSUM
Physiological and Operative Severity Score for the enumeration of Mortality and Morbidity
operation risk calculator
done in emergency
determine what level of anaesthetist is needed
RF for perioperative morbidity
age
men
socioeconomic status - poor = worse
aerobic fitness - a patients functional capacity can be measured in metabolic equivalents (METs) where 1 MET = resting oxygen consumption of a 40yr old 70Kg male
diagnosed MI, HF, stroke, kidney failure (creatinine >150umol/L), peripheral arterial disease - multiply long term morbidity risk by 1.5
angina and TIA increase risk less
COPD/asthma, dm, HTN, hypercholesteraemia
dm peri-op (and pre)
o Take HBA1c
o If not good – send back to GP
o High HBA1c bad because increase chance of infection
o Also starved so you have poor control
o Surgery causes stress – cause increase in glucose, if don’t produce the insulin to counteract that then have issues
o Can give insulin infusion
o Do patient early on in the day so that they’re not starved for too long
o Make sure on the ward that the drs know they’re dm so that they monitor sugar levels so don’t get DKA/hypo/hyperglycaemic
o Can give salbutamol with gas (little effect), can give salbutamol IV (not many people know how to use it)
o ?stop gliptins
o Ask them to only take half their insulin the night before because they will be starved the next day
anaesthetic considerations for COPD
dont want to cause volume trauma - keep lower pressure
o It is the post-op that is the issue
o Because bronchial spasm, pneumonia (most common), pneumothorax because on positive pressure breathing
o Pneumonia because anaesthetics reduce white cell func, they’re immunosuppressants – so get infection from the flora that is in the mouth that is normally fine
o Extubate after operation because better if people breathe on their own. Also it is a moist warm environment for the bacteria to grow. When suctioned – some goes back down = more chance of infection
o Need to get the patient sat up and mobilising as fast as possible = better outcomes
HTN in surgery
alter meds
dont do op until under control
peri-op control of IHD
o Want to keep BP high
o Give infusion of vasopressor in the anaesthetic room
o Do an arterial line while awake
o Fluids
o Need to have a good flow of blood through the coronary arteries in diastole so that the heart can be perfused
how do you reduce the risk of sickling in SCD peri-op
Cold because Vasodilation etc o Warm fluid o Humidify air (also so lungs don’t get dry) o Bair hugger Analgesia • Because the stress of the operation can cause sickling Hypoxia • Make sure preoxygenate well Dry • Lots of warm fluids
peri-op control of asthma
o They can go into bronchospasm easier
o Wont change what you do because all the drugs are bronchodilators anyway
don’t want to cause volume trauma - keep lower pressure
is day or overnight surgery more common
day - 70%
benefits of day surgery
Allows hospital beds to be left free, and the patient to mobilise freely, eat they’re own food and sleep in their own bed
avoidance of stressful preop night has helped reduce need for preop anxiolytics
why do day surgeries sometime -> admission
post op nausea and vom, uncontrolled pain, and lack of social care at home
social criteria for day surgery
pt must understand procedure and post op care and consent
responsible adult should escort the pt home
must have a ‘carer’ post-op
medical criteria for day surgery
functional status determined at pre-anaesthetic assessment and not ASA, age or BMI
pts with stable chronic disease often better as day cases - less interruption to their routine
unstable med conditions not day cases, need to ask if appropriate to do surgery at all when unstable
obesity not a contraindication to day surgery because they can be managed by experts. Obese pts benefit from short-duration anaesthetics and early mobilisation associated with day surgery
obstructive sleep apnoea or identified at risk by ‘STOP-Bang’ scoring not a contraindication - should avoid postop opiods and optimally use regional anaesthesia. Make an individualised decision about whether people should be discharged on the same day
surgical criteria for day surgery
procedure shouldnt carry a sig risk of post op complications requiring immediate medical attention eg haemorrhage or CV instability
post op symptoms inc pain and nausea must be controlled by oral med and local anaesthetic techniques
procedure should not prohibit pt from resuming oral intake in a few hours
should be able to mobilise before discharge
if full mobilisation not possible - full thromboembolism prophylaxis should be instituted and maintained
metabolic equivalents - anaesthetics
1 MET = resting oxygen consumption of a 40yr old 70Kg male:
if they can walk indoors or 100m on level ground - 2-3METs
climb 2 flights of stairs 4METs
participate in strenuous sport eg singles tennis 10METs
when functional capacity high = excellent prognosis even if other risk factors
MET <4 = poor prognosis in thoracic surgery, less so in non-cardiac surgery
in pre-assessment clinic aerobic fitness can be assessed by a shuttle walk or cardio-pulmonary exercise test
Ix done for minor surgery
consider kidney function test in people with AKI if ASA3/4
ECG if ASA 3/4 and not had ECG in 12 months
Ix done for intermediate surgery
FBC - ASA3/4 - if cvs/renal disease if symptoms not recently investigated
haemostasis - ASA3/4 - in chronic liver disease if people taking anticoags need modification of treatment regimen or if clotting status needs to be tested before surgery (depending on local guidance) use point of care testing
kidney func - ASA2 consider if at risk of AKI, routine in ASA3/4
ECG - ASA2 consider with CVS, renal or dm comorbidities, routine in ASA3/4
lung func/arterial blood gas - consider advice from senior anaesthetist if ASA3/4 due to known or suspected resp diseas
ix for major or complex surgery
FBC - routine
haemostasis - as for intermediate
kidney func - ASA1 consider if at risk AKI, ASA2-4 - routine
ECG - ASA1 consider if over 65yrs and no ECG in 12 months, routine in ASA2-4
lung func/arterial blood gas - as for intermediate
do you want long or short neck for intubation
long
considerations of pt has high BMI
o Difficult to put to sleep
o Need to make sure you can bag them
o pPeak higher
considerations if patient gets reflux
o More likely to intubate them – don’t want them to aspirate
why do you need pts NBM before surgery
If food in stomach there is a chance of pulmonary aspiration. Pul aspiration of even 30mL of gastric contents = morbidity and mortality.
timeframe for NBM for children
cow/formula/solid up to 6hrs, breast up to 4, clear fluid up to 2 hours
why do we consider AB in pre-op assessment
tetracycline and neomycin may increase neuromuscular blockade
anticonvulsant considerations pre-op
give as usual pre-op
post op - give IV until can take orally
contraceptive pill and HRT considerations pre-op
increased risk of DVT/PE
stop 4wks before major/leg surgery
restart 2wks post-op if mobile
digoxin considerations pre-op
continue
check for toxicity - ECG, plasma level
plasma K and Ca
suxamethonium can increase K -> ventricular arrhythmias
diuretics considerations pre-op
beware hypokalaemia, dehydration
UE and bicarb
levodopa considerations pre-op
possible arrhythmias when under GA
lithium considerations pre-op
may potentiate neuromuscular blockade and cause arrhythmias
MAOi considerations pre-op
hypertensive/hypotensive crises
Tricyclics considerations pre-op
enhance adrenaline and arrhythmias
malignant hyperpyrexia
rare complication
precipitated by volatile agent eg halothane or suxamethonium
autosomal dominant
rapid temp increase
complications: hypxaemia, hypercarbia, high K, metabolic acidosis and arrhythmias
Mx - dantrolene (skeletal muscle relaxant), active cooling and ITU
