Anaesthetics Flashcards
State the fasting durations prior to surgery
- No food for 6 hours prior to surgery
- No clear fluids 2 hours prior to surgery
Outline 3 pre-medications that may be used by anaesthetics just before surgery and their role
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
Outline 3 components to anaesthesia and examples of drugs used in each component
HAM
- Hypnosis - make patient unconscious
e.g. Propofol (IV), Ketamine (IV), nitrous oxide (inhaled) flurane gases (inhaled) - Analgesia - reduce pain
e.g. Fentanyl and Morphine
Also requires antiemetics e.g. Ondansetron, Dexamethasone - Muscle relaxants - reduce muscle tone
e.g. Sugammadex
Outline some risks of general anaesthesia
Common:
- Sore throat
- Nausea and vomitting
Significant risks:
- Aspiration
- Dental injury
- Accidental awakeness
- Cardiovascular events e.g. MI, stroke
- Anaphylaxis
- Malignant hyperthermia
- Death
Give 3 examples of when a spinal block may be used
- Cesarean section
- TURP procedure (transurethral resection of the prostate)
- Hip fracture repairs
Explain the difference between spinal and epidural block and when each would be used
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)
Outline some risks of an epidural during labour
- Maternal hypotension leading to foetal and maternal distress
- Dural puncture leading to a severe postural headache
- Epidural haematoma and potentially cauda equina syndrome
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
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
Explain the difference between C-fibres and A-delta fibres
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
Describe our best methods used to measure pain
Although there is no reliable way to reliably measure pain, 2 ways we can try to quantify pain:
- Numerical analogue scale
- Ask patient to grade pain out of 10 - 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
State the WHO analgesic ladder and give examples of drugs in each category
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)
List some adjuvant medications that can be used alongside WHO analgesic ladder (good for neuropathic pain)
- Amitriptyline
- Gabapentin
- Pregabalin
- Duloxetine
- Capsaicin cream (topical)
List some side effects of NSAIDs
- Gastric ulcers, gastritis and dyspepsia
- Renal impairment
- Exacerbation of asthma
- Hypertension
List some contraindications for NSAIDs
- Asthma
- Stomach ulcers
- Uncontrolled hypertension
- Heart failure
- Renal impairment
- Heart disease
List some side effects of opiates
- Constipation
- Respiratory depression
- Nausea and vomitting
- Altered mental state (e.g. confusion, sedation)
- Pruritus