anaesthetics Flashcards
what does the pre-op care depend on
Patient co-morbidities & medication
- Type of surgery : minor/intermediate/ complex (including
haemorrhage risk)
- Setting: elective OR emergency
what are the different ASA levels
ASA 1: Healthy patient
• ASA 2: Mild systemic disease. No functional
limitation ie exercise tolerance - no problem climbing 2flights
• ASA 3: Moderate systemic disease. Have
functional limitation
• ASA 4: Severe systemic disease that is a constant
threat to life
• ASA 5: Moribund patient. Unlikely to survive 24
hours, with or without treatment
• Postscript E indicates emergency surgery
summarise POSSUM
o Based on physiological parameters at time, whether emergency or not, operative variables
o Number produced has been validated
o Risk discussion with pt – risk benefit ratio in favour – and if not what does that mean
In peri-op have more invasive monitoring
Post-op if mortality >5% - ITU or high dependency unit (HDU)
If surgeon quotes 1% mortality risk for pt – high risk but for HDU guidelines its 5%
what is important when considering comorbidities
optimisation and peri-operative control
control for dm
look at HbA1c and see how well controlled
think when to use insulin sliding scales
control for HTN
optimisation - when to treat (>160/80)
control - maintain within 20% of normal BP in primary care settings, not in hospital – often high when come in for surgery.
= reduced morbidity and mortality. If 1 hypotensive episode = morbidity and mortality
IHD control
optimisation - Symptomatic (or major
procedure) /ECG anomaly
BP & HR control. Consider post
operative HDU
asthmatic and COPD control
optimisation: Symptomatic? Signs?
Medication – BTS Guideline
anti-coagulants control
optimisation - why are they on them, can we stop them or not
INR/APTR <1.5
Anti-platelets/LMWH
resumption?
sickle cell control
haematology review
good care - warm, hydrated, analgesia, infection free
considerations for day surgery
social - Patient consent, carer, home setup, can they manage at home
medical - Fitness, stable chronic, obesity not
preclude, comorbidities
surgical - Complication risks, controllable post op
symptoms, mobile, how major the surgery is
when should you consider further investigations
dependant on pt and background state
Bloods test anomalies : anaemia, renal dysfunction
Lung function tests : Baseline ABG’s, FEV1<40% (predictor for
postoperative ventilation)
cardiac:
ECG - ischemia, arrhythmia, dm - multisystem disease, HTN
echo - poor functional status (LV function and valves) and reasonable size op/GA
stress echo - gives low/intermediate/high risk index of ischemia - used to quantify ischemia
things to ask in an anaesthetics Hx
o Whether had anaesthetic before and problems o FH of problems o Malignant hyperpyrexia o Suxamethonium apnoea o Both genetically based and run in fam o Drug rn/longer to recover, or awareness, or not take long to recover comorbidities, Ex tolerance medication/allergies smoking/Etoh/recreational drugs teeth - dental work airway - mallampati, neck movement NBM
mallampati socre
1 - Should be able to see all soft pallet and uvula
2 – still uvula, not all of soft pallet
3 – some uvula and not all, ie just base
4 – complete obliteration – no uvula or soft pallet
Ask open mouth and stick tongue out
why do you ask about neck extension
makes a difference for intubation
why starve before surgery
reduce aspiration risk – if when put to sleep have food in stomach/acid that comes up into mouth – airway reflex don’t work – go into lungs – high mortality attached to it – strict about NBM
how long do you starve for
food 6hr
Water 2hrs
caveat if reflux, obese, slow gastric transit eg trauma = reduced transit time – different times
how do you prescribe opioids
o Make sure on form – dose, strength, formulation, total quantity – dosage in words and figures and quantity need supplied for that period of time
o Length and duration time required for
handwritten
summarise oropharyngeal airway
called guedel airway
3 4 5 size - from angle of mandible to side of mouth
Airway adjuncts (not airway in own right) - used with bag mask ventilation
Slits in behind the tongue – allow passage to continue and makes ventilation easier
summarise bag-mask-valve airway
For pt apnoeic/resp failure
One way valve – drive against the lungs
Cant breathe against
So doesn’t work with spontaneous ventilation
Reservoir opens up more ox to be drawn in
FiO2 60-90% – fraction of inspired oxygen
endotracheal tube
o Connector on R hand side
o Labelled with internal diameter
o Markings along tell you how long at teetc
o Pilot balloon – where but air in – connected to balloon at end of tube
o Black marker should be at cords
o Balloon sit below
o This is a definitive airway – cuffed tube in trachea sealing it off (ET, tracheolaryngeal tube)
supraglotic airway
o Igel – sits above the vocal cords o LMA o At bottom- gastric port - traverse in parallel to main ox conduit o Different size 3 4 5 o Paed smaller 1 2 o Single use o Latex not definitive airway
benefits and features of Igel
15mm connector - reliable connection to any standard catheter mount or connection
clearly displayed product info- quick easy reference, confirmation of size and weight preference
position guide - adult size only - confirmation of optimum insertion depth
non-inflatable cuff - made from soft gel-like material allowing ease of insertion and reduced trauma
gastric channel - enhance safety - allows for suctioning, passing of NG tube and venting
integral bite block - reduces possibility of airway channel occlusion
buccal cavity stabiliser - aids insertion and elimates potential for rotation
epiglottic rest - reduces possibility of epiglottis down folding and airway obstruction
what is the need for the 5 steps to safer surgery
o Safety checklist by WHO in developed and non-developed countries – benefits 30-40% improvement in mortality
o Allows a rolling team – communicate with everybody from different teams
steps in the 5 steps to safer surgery
team brief - go through list and introduce yourself, go through order
when pt comes - sign in in the anaesthetics room - check no major allergies, all monitoring in place, have blood if needed, site marked, difficult airway/anaesthetic risk
time out before incision - pts name, allergy, metal work, make sure surgeon know operating on the correct side, equipment sterile, count correct, anaestetics set up, special requirements and concerns, ASA, essential imaging/tests available, duration of op, expected blood loss, any special equipment needed, hair removal, AB, pt warming, glycaemic control, VTE prophylaxis undertaken
sign out - comfirm procedure done and everything accounted for
sign out before pt leaves theatre - has throat pack been removed, swab insturment and needle/sharp count correct, any equipment issues, correct procedure performed and recorded, specimens labelled, post op - analgesia,AB, VTE prophylaxis, fluid management inc blood, care iof drain/NG
debrief - end of day
what do you need to consider for VTE prophylaxis
mobility RF bleeding risk o No different from Virchow’s triad – stasis, OCP, cancer, preg, bleeding risk – pt and type of sugery – high bleeding risk – don’t want VTE prophylaxis. Thrombophilia – more prone to DVT and PE – give longer period and involve haematologist o Drug chart prompt you for it
summarise the WHO pain ladder
step 1 - non-opioid eg aspirin, paracetamol or NSAID +- adjuvant
step 2 - weak opioid - for mild to moderate pain eg codeine/tramadol +-non-opioid +- adjuvant
step 3 - strong opioid - for mod to sever pain eg morphine/oxycodone +-non-opioid +- adjuvant
what anti-emetics are best to use
cyclizine/ondansetron - have best number needed to treat (NNT)
these and dexamethosone NNT are in single figures - very effective
whereas Metoclopramide and Prochlorperazine NNT are in teens
so use these 2nd line
ondansetron mechanism, SE and dose/route
5HT3R-antagonist Bradycardia Long QT syndrome CI in pregnancy 4-8mg TDS PO/IV
cyclizine mechanism, SE and dose/route
H1 R antagonist Tachycardia Anti-cholinergic can cause delerium make young women high 50mg TDS PO/slow IV/IM
dexamethasone mechanism, SE and dose/route
corticosteroid Hyperglycaemia Perineal ‘burning’(transient) 4-8mg BD /IV
metoclopramide mechanism, SE and dose/route
Central DA2 R antagonist Extrapyramidal SE’s acute dystonic reactions involving facial and skeletal muscle spasms and oculogyric crises 10mg TDS PO/IV
prochlorperazine mechanism, SE and dose/route
DA antagonist
Extrapyramidal SE’s
Long QT syndrome
12.5mg BD / IM
why do you need temperature control in surgery
o Normal homeostasis disrupted under GA
Wake up better
Better outcomes
Enzymes operate in certain temp – other wise denature, tight temp boundaries – clotting prolonged if temp low
If pt bleeding considerably and not keeping them warm, not coag and temp not helping
ways to keep pt warm
keep temp >36 degrees
o procedure >30mins = Bair hugger
o longer procedure = Warm up fluids
o Specific heat capacity of water – in winter changes more slowly temp
o Warm fluid more effective in warming pt than convection heating through Bair hugger
resp emergency - asthma outside of theatre
ABC
O2 -Start high flow oxygen and gain IV access
Salbutamol nebulised 2.5-5mg
Hydrocortisone 100 mg IV 6 hourly or prednisolone orally
40–50 mg/day.
Ipatropium nebulised 0.5 mg (4–6 hrly
salbutamol IV if
not responding (250 mcg slow bolus then 5–20
mcg/min).
Theophylline/Aminophylline
Magnesium 2g IV over 20 minutes
In extremis (decreasing conscious level or exhaustion)
adrenaline may be used: nebuliser 5 ml of 1 in 1,000;
Senior clinician only: IV 10 mcg (0.1 ml 1 : 10,000) increasing to
100 mcg (1 ml 1 : 10,000) depending on response
caution with aminophylline
tight therapeutic index – be careful with
periop management of asthma
B2 agonist - salbutamol/terbutaline/salmeterol - convert to nebulised form - high dose may reduce K, causes tachycardia and tremor
anticholinergic drug - ipratropium - nebulised
inhaled steroids - beclomethasone/budesnoide/fluticasone - if on >1500mcg/day of beclomethasone, adrenal suppression may be present
oral steroid - prednisolone - continue as IV hydrocortisone until taking orally (1mg pred = 5mg hydrocortisone) if >10mg/day - adrenal suppression likely
leukotriene inhibitor (anti-inflammatory effect) - montelukast/zarfirlukast - restart when taking oral med
mast cell stabaliser - disodium cromoglycate - inhaler
phosphodiesterise inhibitor - aminophylline - continue where possible - effectiveness in asthma debated, in severe asthma consider converting to an infusion periop (checking levels 12hrly)
identifying a tension pneumothorax
has no lung markings, deviated trachea and mediastinal shift = tension
treatment of tension pneumothorax
o Treat with large bore 16G (grey) catheter or orange 14G – 2nd ICS MCL – needle aspiration – decompress as temporary measure before drain – byes time
triggers of anaphylaxis
stings nuts food AB anaesthetics drugs contrast media latex hair dye hydatid
anaphylaxis recognition - airway
Airway swelling, e.g., throat and tongue swelling (pharyngeal/laryngeal oedema). The patient
has difficulty in breathing and swallowing and feels that the throat is closing up.
• Hoarse voice.
• Stridor – this is a high-pitched inspiratory noise caused by upper airway obstruction.
rest.
recognising anaphylaxis - breathing problems
• Shortness of breath – increased respiratory rate. tripod position • Wheeze • Patient becoming tired. • Confusion caused by hypoxia. • Cyanosis (appears blue) – this is usually a late sign. spo2 <92% • Respiratory arrest
recognising anaphylaxis - circulation problems
Signs of shock – pale, clammy.
• Increased pulse rate (tachycardia).
• Low blood pressure (hypotension) – feeling faint (dizziness), collapse.
• Decreased conscious level or loss of consciousness.
• Anaphylaxis can cause myocardial ischaemia and ECG changes even in individuals
with normal coronary arteries -> Cardiac arrest.
treatment of anaphylaxis
ABC
adrenaline IM when confirmed diagnosis
chlorphenamine and hydrocortisone IM or slow IV
fluid as supportive measure
HDU or ITU depending on how well recover
if pt fit and healthy - will be fine body just pushed to extreme
of old with heart disease already = MI, stroke, renal failure – hard to predict how they would be afterwards
what do you monitor in anaphylaxis
pulse oximetry
ECG
BP
when should you transfuse blood
o 70Hb – unless IHD or neuro disease or severe sepsis – give blood to keep Hb >90
o Depend on how stable – ongoing losses and quick – make judgement call
what is NEWS
based on simple scoring system in
which a score is allocated to physiological measurements already
undertaken when patients present to, or are being monitored in hospital.
what physiological parameters form the basis of NEWS
RR sats temperature SBP pulse rate level of consciousness
how does NEWS work
score allocated to each measure
magnitude of score reflecting how extreme the parameter varies from the norm
score is then aggregated - uplifted if on ox
parameters are already routinely measured in hospitals and recorded on clinical chart
signs that pt is deteriorating
portsmouth sign - HR is higher than SBP
happens over period of time, RR up, sats down
what is the most sensitive parameter
• RR v sensitive – geared around met state of human – if met state not good ie acidotic – RR driven up
interpretation and response to NEWS scores
1-4 = low = monitor min 12hrly - monitor NEWS with every set of obs
5-6 or individual parameter 3 = medium = monitor hourly, nurse inform med team, urgent assessment by clinician, clinical care in env with monitoring fascilities
7 or more - high - continuous monitoring of vital signs - nurse immediately inform the med team at SpR, emergency assessment by clinical team with critical care competencies and someone with advanced airway skills, consider transfer to HDU, or ITU
what is SIRS
systemic inflammatory response syndrome
day 1-2 after surgery – all changes of sepsis w/o infective focus
temp >38 or <36
HR >90
RR >20 or PaCO2 <32mmHg
WBC >12000/mm3 or <4000/mm3 or >10% immature bands
what is sepsis
SERS and infection
management of sepsis
Early recognition and early broad spectrum AB important, fluid to resus – supportive measurement
within 3hrs
- measure lactate level
- obtain blood cultures prior to admin of AB
- admin broad spectrum AB
- Administer 30 ml/kg crystalloid for hypotension or lactate ≥4mmol/L “Time of presentation”
is defined as the time of triage in the emergency department
within 6hr
- Apply vasopressors in ITU/anaesthetics (for hypotension that does not respond to initial fluid
resuscitation) ; maintain a mean arterial pressure (MAP) ≥65 mm Hg
- In the event of persistent hypotension after initial fluid administration (MAP < 65
mm Hg) or if initial lactate was ≥4 mmol/L, re-assess volume status and tissue
perfusion.
- Re-measure lactate if initial lactate elevated - give idea of how utilised ox is by the tissues
indictation for anti-emetics
previous post-anaesthesia illness bowel surgery – because moving it around a lot – more likely to get ill
Young women tend to get ill more
what is given in VTE prophylaxis
compression stockings
LMWH or heparin
SE of hyoscine/atropine
anticholinergic = tachycardia urinary retention glaucoma sedation - esp in elderly
SE of opioids
resp depression reduced cough reflex N and V constipation urinary retention hypotn sedation
SE of thiopental (induction agent)
laryngospasm
SE of propofol (induction agent)
resp/cardiac depression
pain on injection
SE of volatile agents eg isoflurane
N and V
cardiac/resp depression
vasodilation
hepatotoxicity
