Pre-op assessment
PC and procedure
PMH:
Cardiovascular disease: HTN & exercise tolerance -> risk of a cardiac event increased during anaesthesia
Respiratory disease, adequate planned oxygenations reducing risk of ischaemic evens peri-op
Renal disease:effect/causes e.g. anaemia, coagulopathy, biochemical disturbances
Blood loss of IV contrast given during some procedures can cause significant renal dysfunction, so care may be taken
Endocrine disease, specifically diabetes mellitusandthyroid disease
often require specific changes
Female of reproductive age – could they be pregnant?
African or Afro-Caribbean descent – could they have undiagnosed sickle cell disease?
Past SHx
Past Anaesthetic Hx:
Any issues? Were they well post-operatively? Has the patient experienced to any previous post-op N+V?
DHx/Allergies
FHx
Malignant hyperpyrexia
*An autosomal dominant condition -> muscle rigidity (despite neuromuscular blockade) followed by a rise in temperature (requires senior input and support if present)
Social Hx
Smoking history and alcohol intake and their exercise tolerance
Anaesthetic exam & Airway examination (to predict the difficulty of intubation)
American Society of Anaesthesiologists Grade
Depends on Co-morbidities, age, seriousness of the procedure
https://www.nice.org.uk/guidance/ng45/resources/colour-poster-2423836189

Which blood tests would the team perform pre op and why?
FBC
Check for undiagnosed anaemia or thrombocytopenia
U&Es
Assess the baseline renal function, which will indicate potential co-morbid status and help inform any potential IV fluid management intra-operatively
LFTs
Assessing liver metabolism and synthesising function, may help direct medication choice and dosing
Clotting Screen
Any indication of deranged coagulation, such as iatrogenic causes (e.g. warfarin), inherited coagulopathies (e.g. haemophilia A/B), or liver or renal impairment, will need identifying and correcting before surgery
G&S or Cross-Match (X-match)
What is group&save and crossmatch

What imaging would the team perform pre op and why?
Electrocardiogram (ECG): Hx of CVD, major surgery, can provide a baseline if there are post-operative signs of cardiac ischaemia
N.B An echocardiogram (ECHO) can be considered if the person has (1) a heart murmur (2) cardiac symptom(s) (3) signs or symptoms of heart failure.
Chest X-ray: should not be performed routinely
Indications include:
Respiratory illness who have not had a CXR within 12 months
New cardiorespiratory symptoms
Recent travel from areas with endemic TB
Significant smoking Hx
If a patient has a chronic lung condition, spirometry may be of use in assessing current baseline and predicting post-operative pulmonary complications in these patients.
Are there any other important pre op tests besides bloods, ECG and imaging?
tetracyclinealone (doxyclycline) alone
or a combination of rifampicin and fusidic acid can be used for skin and soft-tissue infections caused by MRSA;
clindamycin alone is an alternative.
A glycopeptide (e.g. vancomycin) can be used for severe
above CI linezolid. As linezolid is not active against Gram-negative organisms, it can be used for mixed skin and soft-tissue infections only when other treatments are not available; linezolid must be given with other antibacterials if the infection also involves Gram-negative organisms. A combination of a glycopeptide and fusidic acid or a glycopeptide and rifampicin can be considered for skin and soft-tissue infections that have failed to respond to a single antibacterial.
Tigecycline and daptomycin are licensed for the treatment of complicated skin and soft-tissue infections involving MRSA.
Explain the airway examination
Check for:
Ask the patient to open their mouth and assess:
Neck:
Suggested Ix for Day Case patients include:
For DM patients, perform a routine HbA1c; if >69mmol then discuss with anaesthetist regarding the need to defer the surgery
1. Reassurance
Advice:
Prescription
Referral
Investigations
Observations
Patient understanding and follow-up
Drugs To Stop ‘CHOW’
Clopidogrel – stopped 7 days prior to surgery -> bleeding risk Aspirin and other anti-platelets can often be continued
Hypoglycaemics – DM
OCP or HRT – 4 wks -> DVT risk. Advise the patient to use alternative means of contraception.
Warfarin – ~ stopped 5 days prior to surgery due to bleeding risk and commenced on therapeutic dose LMWH
Surgery will often only go ahead if the INR <1.5, so you may have to reverse the warfarinisation with PO Vitamin K if the INR remains high on the evening before
Drugs to alter
If the patient is on 10mg of pred PO how much do they need during the op?
Subcutaneous insulin – may be switched to IV variable rate insulin infusion.
Long-term steroids – must be continued, due to the risk of Addisonion crisis if stopped
If the patient cannot take these orally, switch to IV (a simple conversion rate is 5mg PO prednisolone = 20mg IV hydrocortisone)

What drugs should we start
When might these drugs be contra indicated
LMWH – the admitting doctor should complete a VTE Risk Assessment and prescribe appropriately
TED stockings – all patients (except vascular surgery patients), need to be prescribed but check for contraindications (especially in the elderly). Contraindications include severe peripheral vascular disease, peripheral neuropathy, recent skin graft, severe eczema.
Abx prophylaxis – orthopaedic, vascular, or GI surgery
Diabetes Mellitus
1.
2.
What is bowel preparation?
who may need it?
why is it less commonly used?
laxatives or enemas to clear their colon pre-operatively.
The exact protocol will vary between hospitals but a general guide is:
fluid shifts can be harmful to patients who are elderly or have cardiac or renal disease,
can prolong patient recovery and length of stay.
Fluid management
important questions to ask

Aim: resuscitation, maintenance, or replacement?
Weight and size of the patient?
Co-morbidities present that are important to consider, such as HF or CKD?
What is their underlying reason for admission*?
What were their most recent electrolytes?
* Total body water = 60% of weight (e.g. 70kg human) = 42L
* 2/3 intracellular (including RBCs) = 28L
* 1/3 extracellular = 14L
o 75% interstitial = 10.5L
o 25% plasma / intravascular = 3.5L
BASE FLUID RESUS WHEN >90 HR

Serum
1. 1 gram of solute per 100ml of solvent
50g in 1L
3.
* Molecular weight of glucose is 180g/mol.
o How many moles in 1L of 5% solution?
* 5% = 50g in 1000mL
* No. of moles in 1000mL = 50g ÷ 180g/mol = 0.278mol
o How many millimoles in 1L of 5% solution?
* 0.278mol × 1000 = 278mmol
o What is the calculated osmolality of 5% dextrose solution?
* Calculated osmolality = 2 Na + Glucose + Urea (mmol/L)
* In 5% dextrose (aka glucose), calculated osmolality = 278mOsm/L
* Some people, add another 2 K+ to the calculation, but this shouldn’t change it too much (2*4 = 8)

What would the osmolality be if you are salt losing, what would it be if you are water losing?

Q1: If 1 gram of dextrose produces 14 kJ energy. How much energy is provided by 1 litre of a 5% dextrose solution? How many kJ does an average adult need? What happens to the dextrose given intravenously in a 5% dextrose solution?
1000mL will stay mostly in the extracellular compartments:
* 75% interstitial = 750 mL
* 25% plasma / intravascular = 250 mL

What factors may increase an individual’s water losses

Explain how you would decide what to give for routine maintenance
What would you do for obese patients?
When would you consider prescribing less fluid (20–25 ml/kg/day fluid)?
25–30 ml/kg/day of water and
1 mmol/kg/day of potassium, sodium and chloride and
50–100 g/day of glucose to limit starvation ketosis
Obese: adjust the IV fluid prescription to their ideal body weight. Use lower range volumes per kg (patients rarely need more than a total of 3 litres of fluid per day) and seek expert help if their BMI is more than 40 kg/m2.
Consequences of fluid mismanagment
Describe the two fluid regimens
Calculate the daily totals of water, sodium, chloride, and potassium for regimens 1 and 2.
Regimen 1
Regimen 2
Na+ (mmol) 150 90
K+ (mmol) 40 60
Cl- (mmol) 190 150
Dextrose (g) 100 120
NICE CG174 1.4.1 state that for maintenance:
* Water = 25-30mL/kg/day
* Na+, K+, Cl- = 1mmol/kg/day (or as I like to remember, “worth your weight in salt(s)”)
* Glucose = 50-100g/day minimum, just to limit starvation ketosis
Why do we match rhesus group?
A RhD- patient will make RhD antibody if they are given RhD+ blood. Clearly, this will not matter for the patient; a RhD- patient, who is given RhD+ blood, and therefore makes anti-D, cannot then go on to attack their own red blood cells as they do not have RhD present on their RBC membrane.
However, this does cause potential problems during pregnancy as anti-D antibodies can cross the placenta, such as may occur in the following example: