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PM3A > (PM3A) Biosurgical Wound Healing > Flashcards

(PM3A) Biosurgical Wound Healing Flashcards

1
Q

Define biosurgery.

A

Use of living organisms in medicine

Biocompatible materials

Biomaterials derived from natural sources

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2
Q

Give some examples of chronic wounds.

A
  • Diabetic foot ulcers
  • Pressure sores
  • Leg ulcers
  • Carbuncles (abscess)
  • Necrotic tissue
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3
Q

What are the main goals for treatment of chronic wounds?

A

(1) Remove necrotic tissue

(2) Prevent infection of wound

(3) Encourage healing

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4
Q

What are the conventional treatments for chronic wounds?

A

(1) Debridement
(2) Gauze dressings + antiseptics
(3) Modern dressings which promote autolytic wound debridement

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5
Q

What is another name for maggot-based therapy?

A

Larval therapy

Maggot debridement therapy (MDT)

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6
Q

What is maggot-based therapy?

A

Use of maggots to clean non-healing wounds

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7
Q

What species of maggot is used in maggot-based therapy?

A

Green bottle fly

Phaenicia sericata

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8
Q

What is Phaenicia seracata?

A

The species of maggot used in maggot-based therapy.

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9
Q

How do maggots debride a wound?

A

Dissolve dead + infected tissue

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10
Q

Are maggots better at debriding gram-positive or gram-negative bacteria?

A

Maggots more effective at killing gram-positive bacteria than gram-negative bacteria

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11
Q

How are maggots thought to promote wound healing?

A

Reported to stimulate formation of granulation tissue

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12
Q

How do maggots break down dead flesh?

A

(1) Serine proteases (trypsin, chymotrypsin, etc)

(2) Aminopeptidases

(3) Allantoin and urea (factors that thin, soften and moisten skin)

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13
Q

What antibacterial substance does a maggot secrete?

A

Seraticin

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14
Q

What is seraticin?

A

An antibacterial substance secreted by maggots

Being developed at Swansea University

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15
Q

What secretions do maggots produce?

A

(1) Factors which breakdown dead flesh

(2) Seraticin - antibacterial substance

(3) Anti-inflammatory factors

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16
Q

Describe the life-cycle of a green bottle fly.

A

(1) Adult produces eggs

(2) Eggs last for 8-24 hours before hatching

(3) Larva hatch and live for 4-7 days

(4) After 4-7 days larvae turn into pupa

(5) After 10-20 days pupa hatch into green bottle flies

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17
Q

How are sterile maggots produced?

A

(1) Eggs are sterilised

(2) Eggs hatch and maggots are packed + shipped

(3) Maggots must be used within 8 hours of receipt

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18
Q

When do maggots stop feeding on necrotic/ infected tissue?

A

5 days after hatching

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19
Q

What is a BioBag dressing?

A

Maggots packaged with foam in pouch (foam protects maggots and soaks up secretions)

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20
Q

What is free-range larvae?

A

Maggots which are allowed free range in the wound

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21
Q

How is a free-range larvae dressing applied?

A

(1) Barriers (i.e. hydrocolloid dressing) applied to protect surrounding skin
(2) Apply maggots to wound
(3) Cover with a moist swab and perforated film dressing
(4) Leave for 3-4 days
(5) Dispose of used dressings and maggots from wound

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22
Q

How might a wound change when using maggot-based therapy?

A
  • Become wetter as maggots produce discharge
  • Active larvae may smell
  • Potential tickling sensation
  • Pain may increase if poor circulation
  • Pain may decrease if infected
  • Rash from secretions
  • Development of a fever
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23
Q

How might pain of a wound change when using maggot-based therapy?

A

May increase if patient has poor circulation

May decrease if patient has infected wound

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24
Q

What types of wounds cannot be treated with maggot-based therapy?

A

(1) Dry wounds

(2) Wounds in body cavities (e.g. mouth)

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25
Q

How can a dry wound be treated using maggot-based therapy?

A

Application of a moist gauze swab

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26
Q

in which patient groups is maggot-based therapy less effective?

A

(1) >60 years old

(2) Deeper/ non-traumatic wounds

(3) Chronic limb ischaemia

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27
Q

What effect does chronic limb ischaemia have on maggot-based therapy?

A

Reduces effectiveness of treatment

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28
Q

What are some benefits of maggot-based therapy over conventional therapy?

A
  • Improved healing time (more cost-effective)
  • Can follow unsuccessful conventional therapy
  • Antibacterial secretions can reduce infection
  • Debride faster than conventional dressings
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29
Q

What are the four humours?

A

(1) Blood
(2) Phlegm
(3) Black bile
(4) Yellow bile

30
Q

When are leeches deemed clinically appropriate?

A
  • Plastic + reconstructive surgeries
  • Impaired venous circulation
31
Q

What are the benefits of using leeches in microsurgery?

A

(1) Drain blood from congested sites

(2) Relieving building pressure

(3) Prevention of blood clots in small veins in grafts

32
Q

How much blood does a leech remove, on average, when it bites?

A

Approximately 5mL

33
Q

How long does a leech bite wound bleed for?

A

10 or more hours

34
Q

How much blood is lost from a leech bite wound?

A

Initially ~5mL

Up to 150mL for next 10 hours following detachment

35
Q

What is the mechanism for the therapeutic benefit of leeches?

A

NOT from initial bite

From 10 or more hours of continued bleeding following leech removal, up to 150mL

36
Q

How to leeches cause the bite wound to bleed for so long following removal?

A

Due to secretions, these include:

  • Anticoagulant
  • Local vasodilator
  • Local anaesthetic
37
Q

What are the main components of leech secretions (saliva)?

A

(1) Anticoagulant
(2) Local vasodilator
(3) Local anaesthetic

38
Q

How long is leech treatment required to restore venous drainage?

A

3-5 days

39
Q

What are the extensive components of leech secretions (saliva)?

A

(1) Hirudin
(2) Calin
(3) Destabilise
(4) Hirustasin
(5) Bdellins
(6) Hyaluronidase
(7) Factor Xa inhibitor
(8) Carboxypeptidase A inhibitors
(9) Acetylcholine
(10) Histamine-like factors
(11) Anaesthetic-like substances

40
Q

What is hirudin?

A

Component of leech saliva

Inhibits coagulation by binding to thrombin

This prevents conversion of fibrinogen to fibrin

41
Q

What is calin?

A

Component of leech saliva

Inhibits coagulation by inhibiting collagen-mediated platelet aggregation

42
Q

What is destabilise?

A

Dissolves fibrin

43
Q

What is hirustasin?

A

Inhibits serine proteases

44
Q

What is bdellin?

A

Anti-inflammatory action

45
Q

What is hyaluronidase?

A

Antibiotic, increases interstitial viscosity

46
Q

What is a Factor Xa Inhibitor?

A

Inhibits coagulation

47
Q

What is a carboxypeptidase A inhibitor?

A

Increase inflow of blood at bite site

48
Q

What is acetylcholine?

A

Vasodilator

49
Q

What are histamine-like factors?

A

Vasodilator

50
Q

What is bivalirudin?

A

Hirudin analogue

Anticoagulant

Reversible

51
Q

What is lepirudin?

A

Recombinant hirudin

Indicated for anticoagulation therapy in heparin-induced thrombocytopenia

52
Q

What is the most common side-effect for hirudin-derived drugs?

A

Bleeding

53
Q

What temperatures to leeches survive in?

A

4-15ºC

Cannot survive in direct sunlight

54
Q

What water requirements do leeches have?

A

Do not tolerate chlorinated tap water

55
Q

What food do leeches require to be kept alive for therapeutic use?

A

None

Can survive for months on a blood meal

56
Q

What are the stages in application of a leech to a patient’s skin?

A

(1) Clean skin with soap + water, then rinse with distilled water

(2) Place a dampened square of gauze, with a hole in the middle, on affected area

(3) Select a lively leech and direct its head to hole in the gauze

(4) Attachment should occur quickly, if not use a needle prick to stimulate this

57
Q

How long will a leech remain attached for?

A

30-60 minutes

58
Q

What is a reason that a leech may detach sooner than intended?

A

Poor circulation

May detach to find a better site

59
Q

What is important when collecting leeches in a container following treatment?

A

Labelled as USED

Dispose of leech

60
Q

What happens to leeches used following treatment?

A

Collected and disposed of

61
Q

How are leeches killed?

A

Sedated with 8% alcohol

Killed with 70% alcohol for 5 minutes

62
Q

How are dead leeches discarded?

A

(1) Sluice

(2) Incinerator

63
Q

Can a leech be used for a second time?

A

NO

64
Q

Can a pharmacy accept a returned leech?

A

NO

65
Q

What must happen following removal of leeches in treatment?
monitoring req

A

(1) Bleeding encouragement by removing any forming clot at wound site
- This must be completed regularly

(2) Routinely check area for infection
- Swab if indicators present

(3) Haemoglobin levels should be checked daily if bleeding is severely prolonged

66
Q

If, following treatment with leeches, bleeding is severely prolonged from the wound what should be done by the healthcare professionals?

A

Measure haemoglobin levels daily

67
Q

What is the main complication with leech treatment?

A

Infection

68
Q

Are leeches sterile?

A

No

They have Aeromonas hydrophila in their gut

69
Q

Which potentially harmful pathogen is present in leeches?

A

Aeromonas hydrophila

70
Q

How is an Aeromonas hydrophila infection treated?

A

Antibiotics

71
Q

When is leech treatment contraindicated?

A

Arterial insufficiency, e.g.

(1) Grafts - vulnerable to infection and leeches are not sterile

(2) Aeromonas hydrophila may become pathogenic in tissues with compromised arterial sufficiency

72
Q

When can leech treatment be considered in patients with arterial insufficiency in the target tissue?

A

When the potential benefits outweigh the risks

PM3A (36 decks)

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