Anaesthetics Flashcards

1
Q

State the fasting durations prior to surgery

A
  • No food for 6 hours prior to surgery
  • No clear fluids 2 hours prior to surgery
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2
Q

Outline 3 pre-medications that may be used by anaesthetics just before surgery and their role

A

Benzodiazepines - reduce anxiety and relax muscles (especially in cardiac surgery where sympathetic drive can influence surgery itself)

Opiates - reduce pain and reduce hypertensive response to laryngoscope

A2 receptor agonists - reduce pain and sedation

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3
Q

Outline 3 components to anaesthesia and examples of drugs used in each component

A

HAM

  1. Hypnosis - make patient unconscious
    e.g. Propofol (IV), Ketamine (IV), nitrous oxide (inhaled) flurane gases (inhaled)
  2. Analgesia - reduce pain
    e.g. Fentanyl and Morphine
    Also requires antiemetics e.g. Ondansetron, Dexamethasone
  3. Muscle relaxants - reduce muscle tone
    e.g. Sugammadex
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4
Q

Outline some risks of general anaesthesia

A

Common:
- Sore throat
- Nausea and vomitting

Significant risks:
- Aspiration
- Dental injury
- Accidental awakeness
- Cardiovascular events e.g. MI, stroke
- Anaphylaxis
- Malignant hyperthermia
- Death

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5
Q

Give 3 examples of when a spinal block may be used

A
  • Cesarean section
  • TURP procedure (transurethral resection of the prostate)
  • Hip fracture repairs
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6
Q

Explain the difference between spinal and epidural block and when each would be used

A

Spinal block goes into the subarachnoid space, directly into the CSF
- Acts on both muscle and nerve fibres
- Used for cesarean section, TURP procedure and hip surgery

Whereas the epidural goes into the epidural space
- Acts on nerve fibres alone and local anaesthetic diffuses to local tissues and through to the spinal cord
- Used for labour and post-operative open surgery (laparotomy)

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7
Q

Outline some risks of an epidural during labour

A
  • Maternal hypotension leading to foetal and maternal distress
  • Dural puncture leading to a severe postural headache
  • Epidural haematoma and potentially cauda equina syndrome
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8
Q

For the following lines, explain how they work and what they are used for
- Arterial line
- Central line / central venous catheter
- Vas cath
- PICC line
- Tunnelled central venous catheter (e.g. Hickmann line)
- Pulmonary artery catheter
- Portacath

A

Arterial line:
- Inserted into an artery e.g. radial artery
- Can be used to monitor blood pressure and take regular ABGs

Central line / central venous catheter:
- Inserted into a large vein with the tip leading into the vena cava (can use internal jugular, subclavian or femoral veins)
- Used for giving medications or blood samples
- Last longer and are more reliable than peripheral cannulas and are better for irritating medications such as inotropes

Vas cath:
- Type of central venous catheter
- Specifically used short term for haemodialysis

PICC line:
- Type of central venous catheter
- Peripherally inserted venous catheter which then leads to the central point (vena cava)

Tunnelled central venous catheter (e.g. Hickmann line):
- Enters through subcutaneous tissue then into the veins (subclavian or jugular) and tip sits in vena cava
- Cuff surrounds the catheter and promotes surrounding healing leading to reduced bacterial infection
- Can be used long term so are good for regular IV treatment

Pulmonary artery catheter:
- Inserted into central venous system and balloon wedges it into branch of pulmonary artery
- Helps to detect pressures in the left atrium for close cardiac monitoring in cardiac centres

Portacath:
- Type of central venous catheter
- Small port under the skin at the top of the chest, used for access (skin remains intact when not needed)
- Tip sits in vena cava or right atrium
- Can be used long term so are good for regular IV treatment

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9
Q

Explain the difference between C-fibres and A-delta fibres

A

C-fibres:
- Small diameter and unmyelinated
- Transmit signals slowly
- Produces dull and diffuse pain sensations

A-delta fibres
- Large diameter and myelinated
- Transmit signals quickly
- Produces sharp and well-localised pain sensations

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10
Q

Describe our best methods used to measure pain

A

Although there is no reliable way to reliably measure pain, 2 ways we can try to quantify pain:

  1. Numerical analogue scale
    - Ask patient to grade pain out of 10
  2. Visual rating scale
    - Ask patient to rate their pain along a horizontal line

Can also use graphical representation of pain in faces for:
- Children
- Learning difficulties

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11
Q

State the WHO analgesic ladder and give examples of drugs in each category

A

Step 1:
- Non opioid medications (e.g. Paracetamol and NSAIDs)

Step 2:
- Weak opiates (e.g. Tramadol, Codeine)

Step 3:
- Strong opiates (e.g. Morphine, Fentanyl)

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12
Q

List some adjuvant medications that can be used alongside WHO analgesic ladder (good for neuropathic pain)

A
  • Amitriptyline
  • Gabapentin
  • Pregabalin
  • Duloxetine
  • Capsaicin cream (topical)
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13
Q

List some side effects of NSAIDs

A
  • Gastric ulcers, gastritis and dyspepsia
  • Renal impairment
  • Exacerbation of asthma
  • Hypertension
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14
Q

List some contraindications for NSAIDs

A
  • Asthma
  • Stomach ulcers
  • Uncontrolled hypertension
  • Heart failure
  • Renal impairment
  • Heart disease
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15
Q

List some side effects of opiates

A
  • Constipation
  • Respiratory depression
  • Nausea and vomitting
  • Altered mental state (e.g. confusion, sedation)
  • Pruritus
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16
Q

State medication used to reverse effects of opiates in life threatening overdose

A

Naloxone

17
Q

State how you would calculate a rescue dose of opiates

A

Rescue dose is 1/6 of their 24 hour background dose

18
Q

State what system is used for the assessment of patients for anaesthetic prior to surgery

A

ASA grade (goes from ASA1-ASA6)

19
Q

Outline the ASA grades for pre-op assessment for anaesthetic

A

ASA grade 1:
- Normal healthy patients
- Non-smokers
- No/minimal alcohol intake
- Good BMI (normal or overweight)

ASA grade 2:
- Mild systemic disease e.g. well controlled diabetes or hypertension, mild lung disease
- Current smoker
- Social alcohol drinker
- Obesity (BMI 30-40)

ASA grade 3:
- Severe systemic disease e.g. poorly controlled diabetes or hypertension, COPD, history of ACS/stroke/TIA >3 months ago
- Morbid obesity (BMI >40)

ASA grade 4:
- Severe systemic disease that is a constant threat to life e.g. MI/stroke/TIA within 3 months, severe valve dysfunction, severe reduction in ejection fraction, sepsis

ASA grade 5:
- Patients not expected to survive the operation e.g. ruptured abdominal aortic aneurysm, massive bleed, intracranial haemorrhage with mass effect

ASA grade 6:
- Brain-dead organ donor

20
Q

List some investigations that you may do prior to surgery

A
  • ECG / echogardiogram
  • Lung function tests
  • Imaging e.g. CT / MRI / X-ray
  • Bloods (U&Es, FBC, HbA1C)
  • Clotting testing
  • Group and Save
21
Q

List some types of medications that may need to be stopped prior to surgery

List 2 medications that may be altered with upcoming surgery

A
  • Hormonal contraception either COCP or HRT (4 weeks before)
  • Clopidogrel (7 days before)
  • Warfarin (5 days before)
  • DOAC (2 days before)
  • Hypoglycaemic diabetic medications
  1. Subcutaneous insulin – may be switched to IV variable rate insulin infusion
  2. Long-term steroids – must be continued, due to the risk of Addisonion crisis
22
Q

State how T1DM is managed alongside surgery

A

Night before surgery:
- Reduce subcutaneous basal insulin dose by 1/3rd

Morning of surgery:
- Miss morning insulin
- Commence an IV variable rate insulin infusion pump (sliding scale with rapid insulin)
- Also dextrose infusion of 5% (whilst the patient is nil by mouth)

Around time of surgery:
- Check the CBG every 2 hours and to alter infusion rate accordingly
- Continue above routine until the patient is able to eat and drink
- At this point, overlap their IV insulin infusion stopping and their normal SC insulin regimens starting (give their SC rapid acting insulin before a meal and stop their IV infusion after they’ve eaten)

23
Q

State how T2DM is managed alongside surgery

A

Depends on how their T2DM is controlled

Diet controlled
- NO action required

Oral hypoglycaemics:
- Metformin: stopped on the morning of surgery
- All other oral hypoglycaemics: stopped ~24 hours before operation
= Instead, patients put on IV variable rate insulin infusion along with dextrose 5% infusion (as with T1DM)

24
Q

State some factors that make a patient high-risk for anaesthetics (may need a pre-op review)

A
  • High BMI
  • Respiratory issues
  • Cardiac issues
  • GORD or other reflux diseases
  • Endocrine issues
  • Previous reaction to anaesthetics
  • Frailty
  • Increased age (general)
  • Sickle cell disease
  • Pregnancy
  • Significant social history e.g. alcoholic
25
Q

State indications where the following blood products would be given:
- Packed red cells
- Platelets
- Fresh frozen plasma
- Cryoprecipitate

A

Packed red cells:
- Acute blood loss
- Chronic anaemia
- Symptomatic anaemia

Platelets:
- Haemorrhagic shock in a trauma patient
- Profound thrombocytopenia
- Bleeding with thrombocytopenia
- Low pre-operative platelet level

Fresh frozen plasma (clotting factors):
- DIC
- Any haemorrhage secondary to liver disease
- All massive haemorrhages

Cryoprecipitate (fibrinogen, vWF, factor 8 and fibronectin):
- DIC with low fibrinogen
- Von Willebrands disease
- Massive haemorrhage

26
Q

List some contraindications for non-invasive ventilation

A
  • Facial trauma (fractures or burns)
  • Reduced conscious level
  • Aspiration risk e.g. vomiting
  • Inability to protect airway e.g. impaired swallow
  • Haemodynamically unstable
  • Patient preference (refusal of treatment)
27
Q

Outline the layers through which the epidural injection and spinal block go through

A

Epidural:
- Injects into the epidural space
- Goes through: dermis, subcutaneous fat, supraspinous ligament, interspinous ligament, and ligamentum flavum (pop) to enter the epidural space (don’t go any further, next layer is the dura mater)
- Epidural space is between the ligamentum flavum and dura mater

Spinal block:
- Injects into the subarachnoid space
- Goes through: dermis, subcutaneous fat, supraspinous ligament, interspinous ligament, and ligamentum flavum (pop), dura mater and subarachnoid mater
- Subarachnoid space is between the subarachnoid mater and pia mater

28
Q

Outline why there is a risk of aspiration at the induction of anaesthesia

A
  • Patient falling into the subconscious
  • Loss of lower oesophageal tone
  • Loss of protective reflexes e.g. cough reflex / gag reflex
  • Horizontal lie, lack of gravity, therefore increased risk of aspiration