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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
How can a dry wound be treated using maggot-based therapy?
Application of a moist gauze swab
26
in which patient groups is maggot-based therapy less effective?
(1) >60 years old (2) Deeper/ non-traumatic wounds (3) Chronic limb ischaemia
27
What effect does chronic limb ischaemia have on maggot-based therapy?
Reduces effectiveness of treatment
28
What are some benefits of maggot-based therapy over conventional therapy?
- Improved healing time (more cost-effective) - Can follow unsuccessful conventional therapy - Antibacterial secretions can reduce infection - Debride faster than conventional dressings
29
What are the four humours?
(1) Blood (2) Phlegm (3) Black bile (4) Yellow bile
30
When are leeches deemed clinically appropriate?
- Plastic + reconstructive surgeries - Impaired venous circulation
31
What are the benefits of using leeches in microsurgery?
(1) Drain blood from congested sites (2) Relieving building pressure (3) Prevention of blood clots in small veins in grafts
32
How much blood does a leech remove, on average, when it bites?
Approximately 5mL
33
How long does a leech bite wound bleed for?
10 or more hours
34
How much blood is lost from a leech bite wound?
Initially ~5mL Up to 150mL for next 10 hours following detachment
35
What is the mechanism for the therapeutic benefit of leeches?
NOT from initial bite From 10 or more hours of continued bleeding following leech removal, up to 150mL
36
How to leeches cause the bite wound to bleed for so long following removal?
Due to secretions, these include: - Anticoagulant - Local vasodilator - Local anaesthetic
37
What are the main components of leech secretions (saliva)?
(1) Anticoagulant (2) Local vasodilator (3) Local anaesthetic
38
How long is leech treatment required to restore venous drainage?
3-5 days
39
What are the extensive components of leech secretions (saliva)?
(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
What is hirudin?
Component of leech saliva Inhibits coagulation by binding to thrombin This prevents conversion of fibrinogen to fibrin
41
What is calin?
Component of leech saliva Inhibits coagulation by inhibiting collagen-mediated platelet aggregation
42
What is destabilise?
Dissolves fibrin
43
What is hirustasin?
Inhibits serine proteases
44
What is bdellin?
Anti-inflammatory action
45
What is hyaluronidase?
Antibiotic, increases interstitial viscosity
46
What is a Factor Xa Inhibitor?
Inhibits coagulation
47
What is a carboxypeptidase A inhibitor?
Increase inflow of blood at bite site
48
What is acetylcholine?
Vasodilator
49
What are histamine-like factors?
Vasodilator
50
What is bivalirudin?
Hirudin analogue Anticoagulant Reversible
51
What is lepirudin?
Recombinant hirudin Indicated for anticoagulation therapy in heparin-induced thrombocytopenia
52
What is the most common side-effect for hirudin-derived drugs?
Bleeding
53
What temperatures to leeches survive in?
4-15ºC Cannot survive in direct sunlight
54
What water requirements do leeches have?
Do not tolerate chlorinated tap water
55
What food do leeches require to be kept alive for therapeutic use?
None Can survive for months on a blood meal
56
What are the stages in application of a leech to a patient's skin?
(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
How long will a leech remain attached for?
30-60 minutes
58
What is a reason that a leech may detach sooner than intended?
Poor circulation May detach to find a better site
59
What is important when collecting leeches in a container following treatment?
Labelled as USED Dispose of leech
60
What happens to leeches used following treatment?
Collected and disposed of
61
How are leeches killed?
Sedated with 8% alcohol Killed with 70% alcohol for 5 minutes
62
How are dead leeches discarded?
(1) Sluice (2) Incinerator
63
Can a leech be used for a second time?
NO
64
Can a pharmacy accept a returned leech?
NO
65
What must happen following removal of leeches in treatment? monitoring req
(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
If, following treatment with leeches, bleeding is severely prolonged from the wound what should be done by the healthcare professionals?
Measure haemoglobin levels daily
67
What is the main complication with leech treatment?
Infection
68
Are leeches sterile?
No They have Aeromonas hydrophila in their gut
69
Which potentially harmful pathogen is present in leeches?
Aeromonas hydrophila
70
How is an Aeromonas hydrophila infection treated?
Antibiotics
71
When is leech treatment contraindicated?
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
When can leech treatment be considered in patients with arterial insufficiency in the target tissue?
When the potential benefits outweigh the risks

PM3A (36 decks)

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