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Our skin is a major organ of the body that acts as a
barrier to pathogens and trauma.
Skin defects caused by burns, venous and diabetic
ulcers, or acute injury occasionally induce lifethreatening situations.
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Many burned people die, their body couldn’t
produce new skin
Skin is largest organs in the body
Skin is important to protect body from
infection and harmful bacteria
Skin keep vital fluid in
Functions of Skin?
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Skin is the largest organ in the human body
Helps preserve fluid balance
Controls body temperature
Helps prevent and fight diseases
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What are wounds ?
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Break in skin or mucous membranes
Any breach in the surface of the body or any
tissue disruption produced by the application of
energy
Usually physical injury
Abrasion injury
Contusion, crush injury
Incision, laceration
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Epidermis (5 layers)
Keratinocytes provide protective properties.
Melanocytes provide pigmentation.
Langerhans’ cells help immune system.
Merkel cells provide sensory receptors.
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Dermis (2 layers)
Collagen, glycoaminoglycans, elastine, ect.
Fibroblasts are principal cellular constituent.
Vascular structures, nerves, skin appendages.
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Hypodermis (fatty layer)
Adipose tissue plus connective tissue.
Anchors skin to underlying tissues.
Shook absorber and insulator.
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Superficial
Deep (blood vessels, nerves, muscle,
tendons, ligaments, bones)
Open Wound
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Superficial or deep break in skin (abrasion,
puncture, laceration)
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Closed: blunt force; twisting, turning, straining,
bone fracture, visceral organ tear
Acute: trauma sharp object or blow
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Surgical incision, gun shot, venipuncture
Chronic: pressure ulcers
Causality
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Intentional: surgical incision
Unintentional: traumatic
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Knife
Burn
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Primary Intention
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skin edges are approximated (closed) as in a surgical wound
Inflammation subsides within 24 hours (redness, warmth,
edema)
Resurfaces within 4 to 7 days
Secondary Intention: tissue loss
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Burn, pressure ulcer, severe laceration
Wound left open
Scar tissue forms
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Inflammatory Response
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Proliferative Phase: 3-24 days
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Serum and RBC’s form fibrin network
Increases blood flow with scab forming in 3 to 5 days
Granulation tissue fills wound
Resurfacing by epithelialization
Remodeling: more than 1 year
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collagen scar reorganizes and increases in strength
Fewer melanocytes (pigment), lighter color
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Age
Nutrition: protein and Vitamin C intake
Obesity decreased blood flow and increased risk for
infection
Tissue contamination: pathogens compete with cells for
oxygen and nutrition
Hemorrhage
Infection: purulent discharge
Dehiscence: skin and tissue separate
Evisceration: protrusion of visceral organs
Fistula: abnormal passage through two organs or to
outside of body
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As wound heals:
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Fluid and cells drain from damaged tissue
Exudate may be:
 Clear
 Bloody
 Pus-containing
Proper wound healing:
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Cleanliness and care of lesion
Proper circulation
Good general health and nutrition
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Vascular Response
Blood coagulation
Inflammation
Formation of new
tissue
Epithelialisation
Contraction &
Remodeling
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Inflammatory
 Bleeding/clotting
 Migration of WBCs
 Cell swelling
Reparative
 Laying down of collagen + migration of epith. cells
 New capillary loops
 Proliferation of fibroblastsstrands of collagen
Consolodative
 reorientation +contraction of collagen
 collagen synthesisdegradation
  vascularity
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Statistics
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Annually, there are approximately 1.25 million people in
the US who sustain burn injuries
Of these, 5,500 do not survive and 51,000 require
hospitalization
Persons whose burn injuries require hospitalization have
about a 50% chance of sustaining temporary or
permanent disability
The most common part of the body involved in burn injury
is an upper extremity, followed by the head and neck
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The primary cause of burn injury is exposure to
temperature extremes
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Heat injuries are more frequent than cold injuries
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Cold injuries almost exclusively result from frostbite
Electrical and chemical injuries constitute 5-10% of
burn injuries and are largely the result of
occupational accidents
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Burn injury causes destruction of tissue, usually the
skin, from exposure to thermal extremes (either hot or
cold), electricity, chemicals, and/or radiation
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The mucosa of the upper GI system (mouth, esophagus,
stomach) can be burned with ingestion of chemicals
The respiratory system can be damaged if hot gases,
smoke, or toxic chemical fumes are inhaled
Fat, muscle, bone, and peripheral nerves can be affected in
electrical injuries or prolonged thermal or chemical
exposure
Skin damage can result in altered ability to sense pain,
touch, and temperature
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Old terminology
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1st degree: only the
epidermis
2nd degree: epidermis and
dermis, excluding all the
dermal appendages
3rd degree: epidermis and
all of the dermis
4th degree: epidermis,
dermis, and subcutaneous
tissues (fat, muscle, bone,
and peripheral nerves)
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New terminology
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Superficial: only the
epidermis
Superficial partial thickness:
epidermis and dermis,
excluding all the dermal
appendages
Deep partial thickness:
epidermis and most of the
dermis
Full thickness: epidermis
and all of the dermis
PRIMARY WOUND DRESSINGS
Primary wound dressing is applied directly
to wounds to protect from contamination,
absorb exudates and facilitate healing.
They are in the form of:
•Self adhesives and do not need a secondary
dressing.
•An interface layer between the wound and
the secondary dressing.
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Maintain humidity
Remove excess exudates
Allow gaseous exchange
Provide thermal insulation
Impermeable to bacteria
Allow removal without causing trauma
Non toxic and non allergenic
Cost effective
Availability
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Gauze Dressings
Transparent Films
Foams
Hydrocolloids
Alginates
Composites
Gauze dressings
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Woven or non-woven materials
Wide variety of shapes and sizes.
Use on: infected wounds, wounds which require packing,
wounds that are draining, wounds requiring very frequent
dressing changes.
Pros: readily available; cheaper than other dressing
types; can be used on virtually any type of wound.
Cons: must be changed frequently, which may add to
overall cost; may adhere to the wound bed; must often be
combined with another dressing type; often not effective
for moist wound healing.
Transparent film dressings
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Allow oxygen to penetrate through the dressing to the wound,
while simultaneously allowing moisture vapor to be released.
Composed of a polyurethane material.
Use on: partial-thickness wounds, donor sites, minor burns,
stage I and II pressure ulcers.
Pros: conforms to the wound well, can stay in place for up to one
week; aids in autolytic debridement; prevents friction against
the wound bed; does not need to be removed to visualize the
wound; keeps the wound bed dry and prevents bacterial
contamination of the wound.
Cons: may stick to some wounds, not suitable for heavily
draining wounds, may promote periwound maceration due to its
occlusive nature.
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Less apt to stick to delicate wound beds, are nonocclusive and are composed of a film coated gel or a
polyurethane material which is hydrophilic in nature.
Use on: pressure ulcers, minor burns, skin grafts,
diabetic ulcers, donor sites, venous ulcers.
Pros: comfortable, won’t adhere to the wound bed, and
highly absorbent; allow for less frequent dressing
changes, depending on the amount of wound exudate;
come in many shapes and sizes.
Cons: may require a secondary dressing to hold the foam
in place; if not changed often enough may promote
periwound maceration; cannot be used on wounds with
eschar or wounds that are not draining.
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Varying types and with different performance features
and indications.
Available in both non adhesive and adhesive.
Allows absorption of exudates.
Uses: Traumatic wounds, Leg ulcers, Minor Burns,
Donor sites.
Examples:
•Lyofoam – allows passage of fluid
•Allevyn – has low-adhering wound contact with
moderate exudates
•Tielle – allows vapour escape with low exudates.
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Very absorbent and contain colloidal particles such as
methylcellulose, gelatin or pectin that swell into a gel-like mass
when they come in contact with exudate.
Strong adhesive backing.
Use on: burns, pressure ulcers, venous ulcers.
Pros: encourage autolytic debridement; provide insulation to the
wound bed; waterproof and impermeable to bacteria, urine or
stool; provide moderate absorption of exudate.
Cons: leave a residue present in the wound bed which may be
mistaken for infection; may roll over certain body areas that are
prone to friction; cannot be used in the presence of infection.
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Consist of insoluble polymers with hydrophilic sites,
which interact with aqueous solutions, absorb and
retain water.
Key Features:
Removes slough and necrotic tissue by rehydrating dead
tissue and enabling autolytic debridement.
Carries metronidazol to treat fungal and other
malodorous wounds.
Uses: Sinuses, Infected wounds, Sloughs and necrotic
wounds.
Examples:
Intrasite gel, Neugel, Granugel.
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Contain salts derived from certain species of brown
seaweed.
Woven or nonwoven
Form a hydrophilic gel when they come in contact with
exudate from the wound.
Use on: venous ulcers, wounds with tunneling, wounds with
heavy exudate.
Pros: highly absorbent; may be used on wounds that have
infection present; are non-adherent; encourage autolytic
debridement.
Cons: always require a secondary dressing, may cause
desiccation of the wound bed, as well as drying exposed
tendon, capsule or bone (should not be used in these
cases).
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Consist, principally of calcium salts of
alginic acid, a polysaccharide derived from
seaweed.
Key Features:
The calcium alginate in contact with the
wound exudates forms a gel on the wound
surface that is believed to facilitate
healing.
The chemical and physical properties
differ in the varieties of alginate on
available.
Plain or impregnated with silver.
Examples:
 Saesorb, Kaltogel, Kaltostat, Sorbsan,
Tegagen, Acquacel.
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May be used as the primary dressing or as a
secondary dressing.
Made from any combination of dressing types, but are
merely a combination of a moisture retentive dressing
and a gauze dressing.
Use on: a wide variety of wounds, depending on the
dressing.
Pros: widely available; simple for clinicians to use.
Cons: may be more expensive and difficult to store;
less choice/flexibility in indications for use.
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The donor site is a new wound.
Scarring and pigmentation changes occur.
Dermis is not replaced.
Donor site is a potential site for infection.
Donor site is not unlimited.
Extensive burns makes it impossible.
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Xenografts, particularly porcine skin grafts, are
commercially available and are an effective means
of short-term wound closure .
• A Xenograft is normally removed on the third or
fourth day of use before extensive adhesion onto
the wound bed sets in, thereby necessitating its
traumatic excision prior to drying and sloughing off.
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The annual
national
requirement for
cadaver skin is
estimated to be
only 3000 m2.
Yet only 14% to
19% of human
skin needed is
being recovered.
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Traditional solution replacing the skin with
another human or animal skin
Some of the body rejects others skin
So, alternative solution needed
Synthetic Skin is invented by Burke and Yannas
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Is laboratory production for substitution of
human skin (tissue Engineering)
Tissue Engineering is Knowledge of building
or repairing human organ
Cells brought from lab or patients blood used
to initiate the process
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Graft should be flexible enough to conform to
wound bed and move with body
Should not be so fluid-permeable as to allow the
underlying tissue to become dehydrated but
should not retain so much moisture that edema
(fluid accumulation) develops under the graft
1.
Protect underlying tissues from injury: mechanical, heat, cold, biological.
2.
Prevent excess water loss.
3.
Act as a temperature regulator.
4.
Serve as a reservoir for food and water: adipose tissue
5.
Assist in the process of excretion: H20, Salt, Urea, Lactic Acid.
6.
Serve as a sense organ for cutaneous senses: pain, heat, cold, pressure,
touch.
7.
Prevent entrance of foreign bodies: microorganisms.
8.
Serve as a seat of origin for Vitamin D.
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Polymeric or collagen-based membrane
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Fabrics and sponges designed to promote tissue ingrowth
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Some are too brittle and toxic for use in burn victims
Flexibility, moisture flux rate, and porosity can be controlled
Have not been successful
Immersion of patients in fluid bath or silicone fluid to prevent
early fluid loss, minimize breakdown of remaining skin, and
reduce pain
Culturing cells in vitro and using these to create a living skin
graft
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Does not require removal of significant portions of skin
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Skin is usually donated by other
donors.
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Fibroblasts are removed from the
donated skin and are frozen until
they are needed.
The fibroblasts are placed on a
polymeric mesh scaffolding, gather
oxygen, and grow new cells.
The cells are then transferred to a
culture system.
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After 4 weeks the polymer mesh dissolves and leaves behind
a new layer of dermal skin.
When the growth cycle is completed, they add more nutrients.
Keratinocytes are added to the collagen and are exposed to
air to form epidermal layers.
The skin is now completed and is stored in sterile contains
until ready to use.
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A high incidence of infection
Low capacity for inducing vascularisation and
epithelialisation
However, useful insights into the requirements for
a satisfactory skin replacement have been
discovered through the use of synthetic polymers.
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"The dermal replacement should provide both the information
necessary to control the inflammatory and contractile processes and
also the information necessary to evoke ordered recreation of
autologous tissue in the form of a neodermis" (Schulz, 2000).
"The initial replacement material should provide immediate
physiologic wound closure and be eliminated once it has provided
sufficient information for reconstitution of neodermis" (Schulz).
It should protect the wound by providing a barrier to the outside
(Beele, 2002)
It should control water evaporation and protein and electrolyte loss
(Beele)
It should limit excessive heat loss (Beele)
It should decrease pain and allow early mobilization (Beele)
It should provide an environment for accelerated wound healing
(Beele)
The risk of infection must be taken into account (Beele)
b) Flexural rigidity of graft is excessive; graft
does not deform sufficiently under its own
weight to make contact with depressions in
woundbed surface, thus air pockets form.
d) Peeling force lifts graft away from woundbed.
f)
Very low moisture flux causes fluid
accumulation at graft-woundbed interface
and peeling.
Types of Skin Replacements
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Epicel skin replacement technology
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Introduced by Genzyme Biosurgery in 1987.
Isolation of individual cells from a postage-stampsized biopsy of skin.
Grow the cells for about 2 to 3 weeks and allow them
to form individual sheets of tissue.
Surgeons transplant these sheets of tissue to the
burnt area where these sheets fuse over time with
the burnt area.
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Artificial skin is already
being used for burn victims
and soon will be available
for other skin disorders.
The skin is not used for a
permanent replacement,
but to temporary cover the
skin until your skin can
grow back naturally.
Benefits
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Protect skin from infection
Keep in moisture to prevent
dehydration
Encourage healing through
construction of new tissue by
infiltration of epidermal cells and
fibroblasts
Allow for less severe scarring
More readily available
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Biodegradable skin
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Slowly releasing antibiotic
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Prevents infection
Re freeze dried artificial skin
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Doesn’t need to be removed
Easier storage and reconstitution
Addition of epithelial growth factor and basic
fibroblast growth factor
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Increased regeneration of tissue
Advantages and Disadvantages of Temporary Skin Substitutes
Product
Advantages
Disadvantages
Biobrane
Can be easily peeled off; good for donor sites and
superficial partial-thickness burns within 6 hrs;
shortens time in hospital; low cost
Temporary coverage
Transcyte
Readily available; easier to remove than
allograft; good for partial-thickness burns;
stimulates epithelialisation; less scarring;
improves healing rate.
Temporary coverage; cost 16 times
more than Biobrane
Apligraf
Immediate availability; 1 step procedure; easy to
handle; primary role is treatment of chronic
ulcers; hastens healing in deep and chronic
wounds; improves cosmetic and functional
outcomes
Temporary coverage; limited
viability; most expensive
Dermagraft
Readily available; living dermal structure; used
for chronic lesions, foot ulcers.
Temporary coverage; only 1 main
application
Advantages and Disadvantages of Permanent Skin Substitutes
Product
Advantages
Disadvantages
Integra
Immediate permanent wound coverage; allows ultrathin split-thickness skin autografts; most widely
accepted for burn patients; allows migration of
patient’s own endothelial cells and fibroblasts; studies
over 10 years now; cosmetically better than using just
autograft; greater elasticity; avoids risk of infection
Complete wound excision; 2 step
procedure; susceptible to infection;
relatively expensive compared to
cadaveric allografts; learning
curve is steep.
Alloderm
Immediate permanent wound coverage; good for
being a template for dermal regeneration; good take
rates; reduces scarring; allows 1 step grafting of an
ultra thin split skin graft
Allograft supply; little barrier
function; no virus screening; 2 step
procedure; most expensive
Epicel
Covers large areas; permanent; immediate permanent
wound coverage; minimal risk of disease
transmission
3 – 5 wks to produce 1.8 m2 from
2 cm2; fragile; expensive because
of quality control; spontaneous
blistering; susceptible to infection
and contractures;
Laserskin
Delivers keratinocytes to the wound in an upsidedown manner
Expensive
Types of Skin
Replacements
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Integra Dermal Regeneration Template®
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Semi -synthetic approach to skin regeneration
Researchers develop a bi-layer membrane
system called the Dermal Regeneration
Template
The first and only FDA approved tissue
engineered product for burn and
reconstructive surgery
Dermal replacement layer is constructed of a
porous, biodegradable matrix of cross-linked
bovine tendon collagen and the glycosaminoglycan chondroitin 6-sulfate.
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Allows a the wound to establish a new tissue base
How does it work?
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Drape a sheet of Integra ®
over the wounded area for 2
to 4 weeks.
Allows the victim’s cells to
grow a new dermis on top of
matrix of the Integra ®.
Remove the top layer of the
Integra® and applies a very
thin sheet of the victim’s
own epithelial cells.
Over time, a normal
epidermis (except for the
absence of hair follicles) is
reconstructed from these
cells.
Skin replacement. Using a bilayer membrane
system, scientists at Integra LifeSciences help
repair skin lesions and burns.
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Using only labor manual process only
50,000 skins produces in a year
So Automated processes needed
Machine that refresh nutrient liquid every
day (increase the time of growth)
Temperature monitor, steady environment
increase the growth