(PM3A) Biosurgical Wound Healing Flashcards
Define biosurgery.
Use of living organisms in medicine
Biocompatible materials
Biomaterials derived from natural sources
Give some examples of chronic wounds.
- Diabetic foot ulcers
- Pressure sores
- Leg ulcers
- Carbuncles (abscess)
- Necrotic tissue
What are the main goals for treatment of chronic wounds?
(1) Remove necrotic tissue
(2) Prevent infection of wound
(3) Encourage healing
What are the conventional treatments for chronic wounds?
(1) Debridement
(2) Gauze dressings + antiseptics
(3) Modern dressings which promote autolytic wound debridement
What is another name for maggot-based therapy?
Larval therapy
Maggot debridement therapy (MDT)
What is maggot-based therapy?
Use of maggots to clean non-healing wounds
What species of maggot is used in maggot-based therapy?
Green bottle fly
Phaenicia sericata
What is Phaenicia seracata?
The species of maggot used in maggot-based therapy.
How do maggots debride a wound?
Dissolve dead + infected tissue
Are maggots better at debriding gram-positive or gram-negative bacteria?
Maggots more effective at killing gram-positive bacteria than gram-negative bacteria
How are maggots thought to promote wound healing?
Reported to stimulate formation of granulation tissue
How do maggots break down dead flesh?
(1) Serine proteases (trypsin, chymotrypsin, etc)
(2) Aminopeptidases
(3) Allantoin and urea (factors that thin, soften and moisten skin)
What antibacterial substance does a maggot secrete?
Seraticin
What is seraticin?
An antibacterial substance secreted by maggots
Being developed at Swansea University
What secretions do maggots produce?
(1) Factors which breakdown dead flesh
(2) Seraticin - antibacterial substance
(3) Anti-inflammatory factors
Describe the life-cycle of a green bottle fly.
(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
How are sterile maggots produced?
(1) Eggs are sterilised
(2) Eggs hatch and maggots are packed + shipped
(3) Maggots must be used within 8 hours of receipt
When do maggots stop feeding on necrotic/ infected tissue?
5 days after hatching
What is a BioBag dressing?
Maggots packaged with foam in pouch (foam protects maggots and soaks up secretions)
What is free-range larvae?
Maggots which are allowed free range in the wound
How is a free-range larvae dressing applied?
(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
How might a wound change when using maggot-based therapy?
- 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
How might pain of a wound change when using maggot-based therapy?
May increase if patient has poor circulation
May decrease if patient has infected wound
What types of wounds cannot be treated with maggot-based therapy?
(1) Dry wounds
(2) Wounds in body cavities (e.g. mouth)
How can a dry wound be treated using maggot-based therapy?
Application of a moist gauze swab
in which patient groups is maggot-based therapy less effective?
(1) >60 years old
(2) Deeper/ non-traumatic wounds
(3) Chronic limb ischaemia
What effect does chronic limb ischaemia have on maggot-based therapy?
Reduces effectiveness of treatment
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