Q2: Active Vacuum: TT Application

Question 1

Atmospheric Pressure

Answer 1

• the force per unit area exerted against a surface by the weight of air molecules above that surface in the earth’s atmosphere
• high pressure areas have more mass above

Question 2

Subatmospheric Pressure

Answer 2

• pressure less or lwoer than that of the atmosphere
• reduction of pressure allows the object to expand

Question 3

Passive Suction Sockets

Answer 3

• intermittent, low levels of negative pressure
• air molecules maintained in given airspace
• passive suction sockets remove minimal amounts of air molecules

Question 4

Active Vacuum Sockets

Answer 4

• constant higher levels of negative pressure
• removal of air actively working on the limb
• reductions of air tends to reduce pressures working on limb
• everything moves towards low pressue
• limb will expand towards low pressure areas

Question 5

Suction Suspension

Answer 5

• pull down on socket
• air space expands
• pressure drops
• suspension force created

Question 6

Vacuum Suspension

Answer 6

• suction suspension expands the sealed volume
• vacuum suspension removes air molecules from fixed volume

Question 7

Hammering with suction suspension

Answer 7

• peak impact pressure 10% higher with suction than vacuum

Question 8

Suction suspension promotes bell clapping

Answer 8

• socket extraction provides room for limb rotation in the socket

Question 9

Socket Extraction and Suspension Force

Question 10

System Components

Answer 10

• liner
• airwick
• socket
• sealing sleeve
• vacuum pump

Question 11

Connections of interest

Answer 11

• liner to limb
• socket to liner
• sleeve to liner

Question 12

Liner to Limb

Answer 12

• liner must make total contact with residual limb
• lubrication may be used on hotspots
• often overlooked
• friction is key especially when moisture is introduced

Question 13

Liner to Socket

Answer 13

• removal of air molecules between liner and socket reduces the atmospheric pressure on the liner
• allows limb/liner coupling to lock the socket walls by expanding

Question 14

Sleeve to Socket/Liner

Answer 14

• important to seal the sleeve to the liner proximally above airwick

Question 15

Residual Limb Volume Control

Answer 15

• more fluid is kept in the limb, promoting hydration and circulation by reducing forces on the tissue in stance

Question 16

Pumping effect

Answer 16

• Stance: increases prssures in soft tissues (pushing blood out of capillaries
• Swing: lowers pressure in soft tissues (pulling blood into capillaries)

Question 17

Prevents Daily Volume Loss

Answer 17

• suction: limb lost 6-10% volume daily
• vacuum: limb maintained or gaint 0-3.7% daily

Question 18

Increased Circulation Theory 1

Answer 18

• internal limb vacuum
• tissue locked to socket
• weight bearing causes excretion of nitric oxide (vasodilator)
• inertia of the limb causes a distraction of tissue
• negative internal pressure of the interstitial fluid mechanism
• helps maintain hydration through gait

Question 19

Microstrain

Answer 19

• micro deformation at the cellular level which leads to cell stretch
• reduces edema
• promotes perfusion
• promotes granulation tissue formation

Question 20

“locked” structure

Answer 20

• cells hydrate and lock against eachother and the bone structure
• minimal internal movement

Question 21

Challenges in AV system

Answer 21

• interact with RL in unique way
• do not allow for varying degrees of movement between limb and socket liner
• attempt to lock the soft limb liner
• high risk high reward

Question 22

Qualifying the patient

Answer 22

• must be enthusiastic and participate in care
• follow directions
• proper hygiene
• cognitivley intact
• K2-K4 (no longer limited by weight activation for mechanical pumps