Preoperative assessment Flashcards
What are the types of anaesthesia available?
- Local: small area numbed to allow for minor surgery
- Regional: local anaesthetic to numb a larger region of the body either central neuraxial blockade (spinal or epidural anaesthesia) and nerve blocks (numbing an entire limb)
- General: either IV or inhaled
Risks of GA
- Major strain on the cardiovascular system
- Major cardiac events
- Chest infection
- Acute kidney injury
- Cerebrovascular events
*For the above reasons it is important to assess patients before surgery
What is ASA grading?
American Society of Anaesthetics scale used to establish a patients fitness for anaesthesia
ASA 1: healthy 💪🏻
ASA 2: mild systemic disease 🤒
ASA 3: Severe systemic disease - not a constant threat to life 🫁🤒
ASA 4: severe systemic disease that is a constant threat to life 🫁😵
ASA 5: patient not expected to survive without surgery ☠️
Outline fasting guidelines before surgery
No solids a minimum of 6hrs prior to surgery
No clear fluids 2hrs before surgery
We fast patients to minimise aspiration risk while they are under GA
What is neuraxial blockade?
Refers to local anaesthetics places around the nerves of the CNS
E.g. spinal anaesthesia, epidural, caudal anaesthesia
Can be used instead of GA or alongside it, to provide high quality pain relief after surgery
Complications associated with central neuraxial block
What is a pre-operative anaesthetic assessment?
Up to 2 weeks before surgery patient will attend a clinic where nurse will ask a series of questions
- Consultant anaesthetist are present in the clinics if any issues arise so that the nurse can consult and the anaesthetist can see the patient if necessary
- The options following this are: op is cancelled, anaesthetist discusses with surgeon to assess anaesthetic options
Parts of the pre-surgery anaesthetic form
3 points of identification must be used
- Patients name
- Hospital number
- ID/ wrist band
Basic obs are recorded by the nurse in the morning
- HR
- BP - slightly higher BP is not the end of the world because anaesthetic medications reduce BP
- Height
- Weight
- Height and weight especially important in paeds cases as drug doses calculated by height and weight
- Temp
- Ask the patient what operation they’re having to make sure they know
- ASA grade: looks at patient’s pre-operative health
- Urgency of case e.g. elective etc
- PMHx
- E.g. rheumatoid arthritis - patients may have neck arthritis and hyperextension of the neck during intubation may be an issue
- Obstructive sleep apnoea: difficult airway, hypoxia
- Drug hx
- What meds are they on: some need to be stopped pre/ post surgery
- Prev. anaesthetic hx
- How were they after anaesthetic? Vomiting? Shivering?
- Any issues in the family with anaesthesia?
- Alcohol/ tobacco/ recreational drugs
- Allergies
Airway and dentition
- Any loose teeth, caps or crowns
Mallampatti score: patient given a number of 1-4 based on what you can see when patient opens mouth
- Score of 1: easy to intubate
- Score of 4: hard to intubate
What is the Mallampati score?
Used to predict the ease of endotracheal intubation
Comprises of a visual assessment of the distance from the tongue base to the roof of the mouth - gives an indication of the space in which there is to work
The higher the score, the more difficult the intubation
Class I: Soft palate, uvula, fauces, pillars visible.
Class II: Soft palate, major part of uvula, fauces visible.
Class III: Soft palate, base of uvula visible.
Class IV: Only hard palate visible.
What does NICE recommend regarding routine pre-operative tests before elective surgery?
- Pregnancy tests: ask all women of childbearing age if they could be pregnant, make sure women know of risks of the anaesthetic if they are pregnant
- Sickle cell disease/ traits: ask patient if they have it or if it runs in the family
- HbA1c for diabetic patients: most recent level should be recorded in referral
X-ray: not routinely offered, only if indicated
Echo: consider if the patient has a murmur and any cardiac symptoms/ signs of HF
The pre-op tests are determined by ASA grade and surgery grade (minor - major/ complex e.g. if it’s major surgery you’d want to do a FBC, group and save, kidney function tests if patient may have AKI
Medications that should not be given on the day of surgery unless instructed by the surgical team
- ACE inhibitors
- ARBs
- Alpha blockers
- the above are sstopped because anaesthetics cause a drop in blood pressure, in combination with any of the above a dangerous drop in blood pressure could occur
- Insulin and non insulin diabetic medication: omit on day of surgery when nil by mouth
- Diuretics: can cause volume depletion and potassium derrangement and interact with anaesthetic agents
Reasons for which DM patients are at higher risk during surgery
Multiple co-morbidities
- Micro and macrovascular disease - at least an ASA grade III
- Increased risk of infection, AKI, ACS, cerebro-vascular accidents
Peri-operative infection
- Wound site infections are more common
- Important to keep blood glucose between 6-10mmol/L throughout hospital stay
Hypo/hyperglycaemia
- Hyperglycaemia is associated with excess morbidity and mortality from systemic infections, wound infections etc
- Hypoglycaemia associated with extended length of stay
DKA and hospital acquired DKA
- DKA can mimic acute surgical abdomen and cause unnecessary surgery
- Lack of administration of insulin will result in a hospital acquired DKA - hospital acquired DKA is the third leading cause of DKA – the other two being infection and treatment non-compliance
- Drug interactions example an elderly patient with diabetes who is taking an ace inhibitor may then be prescribed nephrotoxic drugs for example non-steroidals or aminoglycosides, this, in combination with possible blood loss or intra operative hypotension, can be detrimental
- Development of pressure ulcers
Paternalistic approach to diabetes can be detrimental, where possible patients with diabetes should be encouraged to self medicate
What is the standard method used to manage DM during surgery?
Variable rate intravenous insulin infusion
However it is associated with many complications and comprehensive guidelines are needed to facilitate safe use
Goal of intraoperative/ anaesthetic technique regarding DM
Promotoe early resumption of eating and drinking and return to normal medication following surgery
Discuss ASA grading in diabetes
Type 2/ non-insulin dependent/ well controlled = ASA 2
Type 1/ insulin dependent/ poorly controlled = ASA 1
