Local anaesthetics :p1 Flashcards
What are the unwanted effects of cocaine overdose?
CNS - excitation, euphoria CVS - increased CO, hypertension, vasoconstriction (all sympathetic actions)
What are the unwanted effects of lidocaine overdose?
CNS - restlessness, confusion, tremor (paradoxical) CVS - myocardial depression, vasodilation, hypotension (caused by Na channel blockade)
How can local anaesthetics be administered?
- Surface - mucosal (mouth, bronchial tree), spray/powder 2. Infiltration = directly into tissues - sensory nerve terminal 3. IV regional - distal to pressure cuff 4. Nerve block 5. Spinal 6. Epidural
When would LAs be administered by infiltration?
Minor surgery
Why are LAs by infiltration co-administered with adrenaline?
Adrenaline causes vasoconstriction So LA doesn’t spread (decreases systemic toxicity) And increases duration of action
What is a local anaesthetic?
A drug which reversibly blocks neuronal conduction when applied locally
What is a problem with surface LAs?
Have to use a high concentration Can cause systemic toxicity
When would LAs be administered by regional IV?
Limb surgery
If the pressure cuff is released prematurely when LAs are administered by regional IV, what issue could arise?
Systemic toxicity
Where are epidural LAs injected?
Into fatty tissue of epidural space Spinal roots
When may an epidural LA be used?
Childbirth Abdominal, pelvic, lower limb surgery
When may a spinal LA be used?
Abdominal, pelvic, lower limb surgery
Where are spinal LAs injected?
Sub-arachnoid space Spinal roots
Why are spinal LAs injected with glucose
To increase specific gravity
