Basics of US Regional Anaesthesia - Anaesthesia UK

30 Pages·2009·3.39 MB·English

B US R
asics of egional
A
naesthesia
November 2008
Essential Physics
HIGH frequency = great resolutionbut ppoooorr ppeenneettrraattiioonn
LOW frequency = ppoooorr rreessoolluuttiioonn but great penetration
Potential Advantages of US
• No ionising radiation
•• PPoorrttaabbiilliittyy
• Robust
• Advent of NICE has
increased machine
accessibility
Potential Advantages of US
• Identify target nerve - fascicular pattern, 90% of peripheral nerves have
this pattern.
• White / hyperechoic is peri/epineurium
• Black / hypoechoic is nerve tissue
Transverse Longitudinal
Left interscalene
More proximally where the nerve tissue is more
dense the nerve can appear more hypoechoic –
black bubbles with white borders.
Potential Advantages of US
• Identify surrounding structures e.g. blood vessels,
pleura, peritoneum
•• DDeetteerrmmiinnee bbeesstt aapppprrooaacchh ttoo ttaarrggeett nneerrvvee
• Real time guidance
• Patients with neuropathy do not respond normally
to PNS
• Observe local anaesthetic distribution
Normal Anatomy ?
Potential Advantages of US
• Faster onset of block
• Assess catheter position
• Repeat block if extended surgery
• Paralysed patient!
Additional Advantages in Children
• Under GA – warning signs of intravascular
or intraneural injection may be masked
•• SSmmaalllleerr mmaassss ssoo nneerrvveess mmoorree ssuuppeerrffiicciiaall ssoo
allowing higher frequencies to be used
• Less margin for error as vulnerable structures
such as pleura are closer to nerves