P14: Wounds & Dressings Flashcards
what is a wound
any defect or damage in the skin caused by physical, chemicl or thermal factors; damage caused by an infectious disease
result of disruption of normal anatomical structure and function
what is an incision
regular wound caused by a clean sharp-edged object
what are lacerations
rough irregular wounds, caused by crushing or ripping forces
what are abrasions
grazes
superficial wound caused by a sliding fall onto a rough surface
what are puncture wounds
caused by a sharp-pointed object punching the skin; high risk of anaerobic infection, injury of big vessels and nerves
what are penetration wounds
caused by a knife entering the body
what are avulsion wounds
when the integrity of any tissue is compromised
what is a contusion
bruise
caused by blunt force trauma, damaged tissues under the skin
what is a hematoma
caused by damage to a blood vessel, blood accumulation under the skin
what are crushing injuries
caused by blunt force, pressure injury over a long period of time
what does the wound healing process involve
dynamic interactive process involving; parenchymal cells, extracellular matrix, blood cell and soluble mediators
what is homeostasis (vasoconstriction) during the inflammatory phase
first bleeding occurs at the site to remove toxic waste; then activation of homeostasis begins
how does the clotting mechanism work during the inflammatory phase
elicited by platelets resulting in coagulation and the formation of fibrin network; the inflammation causes vasodilation and hagocytosis -> release of histamine and serotonin
phagocytes enter the wound, engulf dead cells, platelets are liberated and form aggregates as part of the clotting mechanism
what happens during granulation in the proliferation phase
migrating cells travel about 3cm from the point of origin in all directions; process occurs 2 days - 3 weeks following injury; results in granulation tissue at the wound space
what is granulation
the effect of fibroblasts and macrophages provising a continuing source of growth factors for stimulating angiotensins and fibroplasia (production of fibrous tissue)
what happens during contraction and angiotensins during proliferative phase of wound healing
fibroplasia results in formation of a bed of collagen to fill the defect, so wound edges pull together
(contraction) and new capillaries are produces (angiotensins)
what happens during the remodelling phase of wound healing
involves formation of collagen to increase tensile strength
begins 3 weeks post-injury up to months; principle cells involved are fibroblasts, collagen molecules formation, further modification to form in a characteristic helical structure; collagen is released in extracellular space to form stable cross links, collagen matures more at the wound its resulting in intra and intrer-molecular cross links forming
cross linking provides strength and stability to collagen
the tissue will never regain the properties of uninjured skin
what do myofibroblasts do in normal tissue
microvasculature is stable and covered by pericytes and inactivated fibroblasts occupy the surrounding connective tissue
what do myofibroblasts do during wound healing
activated fibroblasts or pericytes may differentiate into myofibroblasts and enter the wound bed
signals and matrix from the wound microenvironment may cause pericytes to assume a more contractile and matrix depositing phenotype
what dressings are used in primary wound dressing
hydrogel dressing, hydrocolloids, gauze impregnated, gauze non-impregnated, composite dressings, wound fillers, alginate dressings, foam dressings
what dressings are used in secondary dressing
tape, elastic bandage, transparent film dressings, gauze dressing, carbon dressing
when are petroleum impregnated dressings used
for clean, healthy wounds with minimal granulation bed; for wounds with no need for debridement/granulation/contraction, used at early stage wound repair for shallow wounds, increases wound contraction but delays epithelialisation
what are non-adhering dressings used for
dry to highly exuding wounds where adherance of dressing and exudate is to be prevented, including first and second degree burns, abrasions, grafts, venuous ulcers, pressure ulcers, nail extractions, eczema, staples, surgical incisions, lacerations, reconstructive procedures and suture lines
what are hydrogel sheets used for
shallow wounds
like burns, fungating, lesions, low exuding wounds
what are some examples of hydrogel sheet dressings
cross-linked sterile hydrogel, solid polymer matrix with propylene glycol, dependent on wound conditions as it maintains moisture balance, no maceratino of the skin surrounding the wound
what are hydrogel gels used for
cavaties, effective for dislodging and debriding
what are hydrogel gels and sheets used for
rehydration of hard eschar and necrotic wounds;
donate moisture, permits autolytic debridement, increases collagenase activity in burns, promotes granulation and epithelialisation, promotes contraction
when are hydrocolloid wound dressings used
early to mid-repair phase of healing; can reduce pain in wounds, encourages angiogenesis in acute wounds
what are hydrocolloid wound dressings used for
wounds with the need for granulation, minimal to moderate exudates, advanced wound contraction, decupital ulcers, pressure ulcers, bed sores, burns, cavity wounds
how do hypercolloid wound dressings work
occlusive to semi-occlusive, highly absorbent, promotes moist wound healing, promotes autolysis to debride wounds that are sloughy and necrotic, promotes granulation (may cause hypergranulation), adhesives may reduce contraction
what is foam dressing
non-adherent dressing that can absorb large amounts of exudates several times their own weight and accumulate the exudate at the back of the dressing
can also be used as secondary dressing
what are foam dressings used for
inflammatory or repair phase of healing, deep wounds with mild to moderate exudates, decubital ulcers, can be used at any stage of healing, best used after granulation to encourage epithelialisation and contraction
what are alginate dressings
natural polymer from brown algae, composed of mannuronic or guluronic acid complexes, good gel and film forming properties
calcium alginate is mainly used in the formation of wound dressing and used in hemostatic agent which encourages the clotting cascade within a bleeding wound
what are the indications of alginate dressings
burns, shearing/avulsion injuries, cavity wounds
encourages wound healing and best at early repair phase
highly absorptive, encourages epithelialisation, promotes autolytic debridement and granulation
what are film dressings
semi-permeable dressings, primary and secondary dressings, comfortable dressings, resistant to shear and tear, prevent bacterial solonisation but do not absorb exudate, vapour permeable, allow fluid to evaporate while keeping the wound moist
what natural polymers are used in wound healing
animal, microbial, vegetal
what are natural polymers made of
protein (fibrinogen, thrombin, collagen, gelatin, albumin)
polysaccharide (chitosan, chitin, polyN-acetyl glucosamine, cellulose)
what are the advantages of natural polymers
biocompatibility, biodegradability and hydrophilicity
what are the limitations of natural polymers
batch to batch variability, large heterogeneity, prone to high biodegradability
what is collagen
natural polymer, most abundant protein in the body, promotes healing by allowing attachment and migration
causes blood clotting through a pathway similar to physiological haemostasis
how many types of collagen are there
25
what is collagen made from
three polypeptide chains with triple helical domains
what is dry collagen used for
physically absorb blood by trapping blood cells and effectively adhere them to the wound site, providing mechanical strength
what is chitin
versatile materials processed into fibres, sponges, membranes, beads and hydrogels
what are the two main polysaccharides in hemorrhage control
randomly distributed beta-1,4-linked D-glucosamine and N-acetyl-D-glucosamine
how is chitosan prepared
from deacetylation of chitin by enzymatic or alkaline hydrolysis
what is chitosan
natural polymer used in wound dressing
what is the source of chitosan
exoskeleton of crustaceans
what are the properties of chitosan
bioactive in slightly acidic media, depolymerises to release beta-1,4-linked D-glucosamine which initiates fibroblast proliferation and aids collagen deposition during the wound healing; it has hemostatic properties
involved in rapid mobilisation of platelet and red blood cells to the injured site during the healing process; also helps in vasoconstriction and activates blood clotting factors
what are the advantages of synthetic polymers involved in wound healing
overcome shortcomings of the natural polymers
synthesised and modified in a controlled manner
what are the disadvantages of synthetic polymers involved in wound healing
biologically inert, so do not offer the therapeutic advantage of natural polymers
what is polyvinyl alcohol
moulded in many dressing forms such as foams, films, particles, sponges and fibres
what is polyethyleneoxide and polyethylene glycol
advantageous in healing process; non-toxic, biocompatible, non-immunogenic, hydrophilic and flexible
can be used to further incorporate mediators such as growth factors to assist the healing process
