Chapter 12 Instrumentation Flashcards
What is blade % of lenght of Mayo Scissors?
And Metzenbaum?
Mayo blades 33% of length
Metzenbaum blades 25% of length
What is the difference between a chisel and osteotome
Chisel is only beveled on one side
(vs osetotome which is beveled on both sides)
What is the benefit of textured tungsten carbide needle holder
- Intermediate needle-holding security
- While minimizing the potential for suture material damage and breakage during know tying
What angle should needle holder ratchets be?
39º
(rather than 45º to enhance security of engagement, with clamping moment less than yield moment).
N.B. Should be able to securely clamp needle with box lock closed to second tooth
At what ‘tightness’ should needle holder securely grip needle?
Closed to second tooth)
How does direction of forceps serrations affect function
Jaw/transverse serrations designed for tip clamping
Longitudinal serrations for jaw-clamping (e.g. OVH pedicle)
What is difference between Debakey and Cooley (non-crushing tissue forceps N.B. Not thumb forceps)
Unique pattern of longitudinal ribs
How do Crile haemostatic forceps differ from Kelly
Longitudinal serrations of Crile extend 100% of jaws (as do halsted mosquito ones), while Kelly ends about 75% of length
List 3 bascic characteristics that microsurgical instruments should have
- Satin finish to minimise glare
- Adequate lenght to allow pencil grip
- Gentle enough closing tension for spring loading
How should instrument milk be applied
Manually, not by spraying
How long does it take for blood on surface of instrument to start breaking down its surface
10 mins
At what tooth should haemostat clamp
1st
(c.f. needle holder which should securely hold needle at second ratchet)
Which instruments should not be flash autoclaved and why?
Microsurgical and ophtho because high heat detrimental to fine points
In what % of new instruments were flaws identified?
15%
List 3 elements that contribute to breakdown of autoclaved instruments
- Tap water
- Metallic ions from residual detergent on surgical wraps
- Moisture
What is pitting corrosion
And fretting?
Pitting corrosion is characterized by pinprick-like holes surrounded by discolored spots.
Fretting corrosion manifests as brown discoloration on a friction surface caused by microabrasive destruction of the passive layer.
To avoid:
- Lubricate
- Use demineralized water
- Neutral pH cleaning agents
What causes rust?
Rust particles in water/steam or non-corrosion resistant steel
What causes yellow-brown/blue-violet disoloroation?
How is it treated
Silicic acid (leakage from water treatment equipment)
Removed by acid-base cleaning with special detergents
What type of instrument degradation is blood most liekly to cause?
Pitting corrosion
What does corrosion resistance of stainless steel depend on?
Quality and thickness of passive layer
(layer resulting from chemical reaction of chromium and ambient oxygen)
Go to chapter (p166) and go through instruments to make sure know the names!
Done?
