Chapter 19: Bandages and Drains

Question 1

What is Laplace’s law in regards to bandages?

Answer 1

The pressure applied under each point under a bandage is proportional to (N x T)/(R x W)

N=number of bandage layers, T=bandage tension, R=radius of curvature of body part, W=width of bandage material under tension

Question 2

What is the pressure at which arterioles to the skin and to the underlying muscle are compromised?

Answer 2

• Skin 30mmHg
• Muscle 50mmHg

Question 3

List the three main methods of pressure relief in bandages:

Answer 3

• Doughnuts
• Windows
• Splints

Question 4

List five techniques for anchoring bandages?

Answer 4

• Stirrups
• Tape strip overlays
• Torso straps
• Figures-of-8
• Incorporating hair
  -tie-over (use ioban to cover)

Question 5

List three benefits of drains:

Answer 5

• Remove accumulations of serum and blood that provide a media for bacteria
• Pressure relief (pressure can compromise perfusion and cause pain)
• Evacuation of inflammatory mediators, bacteria, necrotic tissue and foreign material

Question 6

What are the two main types of reservoirs on active drains?

Answer 6

• Compressible
• Rigid

Question 7

What is the recommended negative pressure generated in human drains?

Answer 7

• 25-74mmHg for delicate tissue
• 75-250mmHg for heavier exudate or large areas
• 200-400mmHg to encourage active adhesion

Question 8

What pressures can be generated by a grenade bulb using various methods of compression?

Answer 8

• 170mmHg when rolled from apex to base
• 110 when compressed with 2 hands
• 84 when compressed with 1 hand

Question 9

What is the decision to remove a drain based on?

Answer 9

The quantity and quality of the fluid and ongoing drain function

One study found significant lower incidence of seroma formation in SQ wounds when the drain was removed when the productions was below 0.2mh/kg/hr