Perioperative care Flashcards
What is epidural anaesthesia?
Epidural anaesthesia is a form of regional anaesthesia that involves injection/infusion of anaesthetic medidcation into epidural space
What are features of an epidural?
-Drug injected into epidural space
-Can be performed at any level along spinal column
-Slow onset (15-25 minutes)
-Large volume (10-20ml) LA +/- opioids
-Large needle (16G) used
-Usually epidural catheter is inserted for repeated doses or infusions
Spinal features:
-Drug injected into subarachnoid space
-Can be performed at level below termination of spinal cord
-Rapid onset (usually <5 minutes)
-Small volume (2-4ml) LA +/- opioids
-Single shot given with thin needle (25G)
What are diffeneces between epidural and spinal?
-Space injected (Epidural vs subarachnoid)
-Level performed (any level vs below termination)
-Onset (slow vs rapid)
-Volume injected (large vs small)
-Needle used (large vs small)
-Number of infusions (multiple vs few)
Describe layers encountered when inserting needle into epidural space
-Skin
-Subcut fat
-Supraspinous ligament
-Interspinous ligament
-Ligamentum flavum
Describe the effects of epidural analgesia
Sympathetic block of transmission of signals through nerve roots near the spinal cord
How can epidurals cause bradycardia?
-‘High epidural block’: spread of LA affecting spinal nerves above T4
-blocks cardio-accelerator fibres
-Leads to unopposed parasympathetic action of vagus nerve
What is a high epidural block?
-Results from excessively large dose of local being injected into epidural space
-Spread of LA affecting nerve roots above T4
-Hypotension, sensory loss or paraesthesia high thoracic/cervical nerve roots
-Bradycardia: blocking of cardio-accelerator fibres leading to unopposed parasympathetic cardiac innervation via vagus nerve
-Dyspnoea due to blockade of nerve supply to intercostals + diaphgragm
How would you assess level of epidural blockade?
-Pain and temp are conducted by same nerve fibre types
-Therefore the only appropariate test is to assess ability to detect cold stimulus which is impaired in blocked dermatomes with either ice or ethyl chloride spray
How do you treat hypotension resulting from epidural block? What is mechanism behind hypotension?
-Pt is hypotensive due to vasodilatation secondary to sympathetic block
-Stop epidural
-IV fluid resuscitation
-Vasoconstrictor drugs: metaraminol
What is the mechanism of high epidural block induced bradycardia? How is it treated?
-Cardio-accelerator fibres originate between T1-T3. Epidural/spinal blockade results in bradycardia from unopposed parasympathetic (vagal) tone
-This is treated with atropine or glycopyrrolate
-Sometimes adrenaline, dobutamine or isoprenaline may be needed
Describe the WHO analgesic ladder
-Mild pain: simple oral analgesics e.g. paracetamol, NSAIDs
-Moderate pain: combined therapies, oral weak opioids eg. tramadol, codeine
-Strong pain: opioids +/- oral analgesics e.g. IV/IM opioids, PCA
-Epidural
What is a fistula?
A fistula is an abnormal communication between two epithelialised surfaces
How does a fistula differ from a sinus?
A sinus is a blind-ended track lined by granulation tissue, which normally connects an abscess to the skin
How would you classify fistulae?
-Congenital e.g. tracheo-oesophageal fistula
-Aquired based on organ e.g. colo-vesical fistula, anorectal fistula, enterocutaneous fistula, entero-enteric fistula
-Surgically controlled fistula e.g. arterio-venous fistula, gastrostomy/jejunostomy/caecostomy
-Low vs high output fistula
What are the complications of peg feeding?
-Infection at PEG (percutaneous endoscopic gastrostomy) site
-Mechanical problems: blockage, accidental removal
-Aspiration pneumonia
-Peritonitis
