Biosurgical Products Flashcards
Describe the principles of treatment of chronic wounds. (3)
Remove necrotic (dead) tissue
Prevent wound infection
Encourage healing
What are the conventional treatments of chronic wounds?
Debridement by surgical/sharp, mechanical, chemical, enzymatic or autolytic removal of dead tissue
Traditional gauze dressings and antiseptics (cheap but require more care)
Modern dressings that promote autolytic wound debridement and prevent infections (i.e. Hydrogel, hydrocolloid, alginate dressings etc) are expensive but improve healing times (average time to healing 89 days) and require less care
What is maggot-based therapy/ larval therapy/maggot debridement therapy (MDT)?
Use of live maggots to clean non-healing wounds
Clinical applications of use sterile larvae of the green bottle fly (Phaenicia sericata)
Describe the history of using maggot in therapy?
Military surgeons in 19th century observed that maggot-infested wounds healed faster and had a lower mortality rates than non-infested wounds
This observation led to maggot therapy being routinely performed until mid-1940s, at which time it lost favour
Why?
Revival of maggot therapy began in 1970s and 1980s.
Why?
How do the maggots work?
The clean wounds by dissolving dead, infected tissue
Disinfect the wound by killing bacteria
Prevent further infection
Actively promote wound healing - reported to stimulate formation of granulation tissue
What do maggot secretions contain?
Contain factors to breakdown “dead” flesh
Serine proteases (trypsin, chymotrypsin etc)
Aminopeptidases
Allantoin and urea (factors that thin, soften and moisten skin)
Antibacterial substances
Seraticin (new antibiotic being developed by researchers at University of Swansea)
Anti-inflammatory factors
Describe the life cycle of the green bottle fly
Adult lays the eggs, hatch in 8-24 hours.
1 day larve are 1-2 mm long
4-7 days old mature maggots are 10mm long
Mature maggots stop feeding at 4-5 days and transform into pupa
Pupa - 10-20 days
Describe the production of sterile maggots
Fly eggs are sterilised
Eggs hatch and the sterile maggots are packaged and shipped
Maggots must be used within 8 hours of receipt
- Maggots will stop feeding 5 days after hatching
How can maggots be applied?
- Free range larvae can be applied directly to the wound. Products include Larvae 300
Best used for cavity or undermining wounds and larger wounds - Contained larvae dressings. e.g. BioBag dressings
Maggots are packed with foam in pouch (foam protects maggots and soaks up secretions)
Preferred by patients but may be less effective
What is the process for applying free larvae to a wound?
- Barrier applied to protect surrounding skin
- Apply maggots to wound
- Cover with a moist swab and perforated film dressing
- Leave for 3-4 days
- Wash maggots from wound (discard in clinical waste)
Describe what a patient might notice when maggots are used on their wound
Their wound might change….
Become wetter as a dark red/pink discharge is released when maggots breakdown dead tissue
Smell from active larvae (especially if wound contains much dead tissue)
Some report tickling sensation
If patient has poor circulation, pain may increase
If wound is infected, pain may decrease
Secretions may cause a rash
They may develop a fever
What wounds cannot be treated with maggots?
Dry wounds (but a moist gauze swab may be sufficient to provide moisture)
Wounds in body cavities
Describe the factors influencing outcome of maggot therapy of ulcers
NOT influenced by sex, diabetes, smoking, locations of wound, wound size, duration of wound
Influenced by age: less effective if >60 years)
Influenced by type of wound: less effective on non-traumatic wounds or deeper wounds
Less effective in chronic limb ischaemia
Why would you consider maggot therapy over conventional therapy?
Difficult to treat or wounds unresponsive to treatment
Maggots have been shown to clean wounds (debridement) more quickly than conventional dressings
Maggots can aid the management of infected wounds through anti-bacterial secretions
MRSA infection eliminated in 92% patients within 3 weeks with maggot therapy (range 1- 6.5 weeks) compared to 28 weeks with conventional treatment (range 3-60 weeks)
Faster healing times achieved with maggot therapy can benefit patient and can also be cost effective.
Describe the historical use of leeches
First reported clinical use of medicinal leeches occurred approximately 2500 years ago
Hirudotherapy was traditionally (and still is) used as a cure all (headache to arthritis) by many cultures (blood letting)
Hippocrates used leeches to balance the four humours of body (blood, phlegm, black bile and yellow bile)
Extremely popular treatment in mid-1800s
