20

Question 1

Laplace’s law for bandaging pressure

Answer 1

p = # T/ RWP= pressure# number of layersT tensionR radiusW width

Question 2

normal closing pressure of skin vs muscle arterioles

Answer 2

30 mm Hg skin arterioles50 mm Hg muscle arteriolesskin can be easily compromised with too much P on bandage

Question 3

degree of bacterial aerolization during bandage change with dry dressings

Answer 3

aerolization of bacT was 20% higher when a dry gauze was removed vs a moisture retentive dressing was removedremains in air ~ 30 min

Question 4

types of drain material that incites the MOST inflammation

Answer 4

MOST red rubber and latexLEAST polyethylene, polyvinyl chloride, silastic (silicone)

Question 5

open passive drain characteristics

Answer 5

PENROSEsoft, pliable, latex, radio opaquedrainage occurs via capillary action (outside), gravity dep, overflow from wound or fluctuation of pressure in wounddrainage is proportional to surface area of drainnot for body cavity

Question 6

closed active drain characteristics

Answer 6

vacuum pulls fluid into tube systemfenestrationsno gravity depdecreases risk infectionprevents skin excoriation by drain fluidcontinuous or intermittent

Question 7

rule to follow when adding fenestrations to a drain

Answer 7

make fenestrations < 1/3 tube diameter to prevent kinking/breakage

Question 8

types of closed suction active drains

Answer 8

compressible reservoirs: JP drainRigid reservoirs: Synder drainSump pump drainsneedle/syringe/tubebutterfly cathetervacuum assisted drains

Question 9

VAC guidelines (TJ) for draining tissues

Answer 9

60-125 mm Hg25-75 mm Hg delicate tissues75-250 mm Hg heavy exudate/dead space200-400 mm Hg to encourage adhesion250-350 mm Hg large volume fluid

Question 10

Poiseuille’s law of laminar flow

Answer 10

flow = dPpir^4/8nLdP = pressure difference btwn to ends of drainr = radius of drainn = viscosity of fluidL =drain length

Question 11

doubling drain diameter does what to flow

Answer 11

2x drain diameterincreases flow ^ 4 power (16 x)flow is directly proportional to radius to fourth power

Question 12

halving the drain length does what to flow

Answer 12

1/2 drain lengthincreases flow 2xflow is indirectly to drain length

Question 13

compare grenade compression pressure generated one hand vs two hands vs roll base to apex

Answer 13

one hand 84 mm Hgtwo hands 110 mm Hgroll base to apex 170 mm Hg****

Question 14

when does grenade lose suction

Answer 14

loses suction as it fills (20-30%)therefor empty grenades before they become half full

Question 15

reasons why a drain should NOT exit the main incision

Answer 15

1. provides an entry point for bacteria2. increases the risk for incisional infection/dehiscence3. increases the risk of herniation4. FOR PENROSE, leads to spread of drainage fluid along incision line

Question 16

reasons for drain failure

Answer 16

1. inadequate tube diameter2.improper placement3. plugging/kinking4.retrograde contamination5. loss of negative pressure6. premature removal/self mutilation