VMS 3010 Wound and Wound Healing 2024 PDF

WOUND AND WOUND HEALING VMS 3010 ALISON LIVESEY 2024  LEARNING OBJECTIVES By the end of this lecture you should be able to: Demonstrate an understanding of the phases of wound healing Describe influences on the speed and completeness of wound healing...

WOUND AND WOUND HEALING VMS 3010 ALISON LIVESEY 2024  LEARNING OBJECTIVES By the end of this lecture you should be able to: Demonstrate an understanding of the phases of wound healing Describe influences on the speed and completeness of wound healing Wound and Wound Healing September 2024 2 W H AT I S A W O U N D ? Wound and Wound Healing September 2024 3 W H AT I S A W O U N D ? Wound, break in the continuity of any body tissue Wound and Wound Healing September 2024 4 W H AT I S A W O U N D ? Does not always mean broken skin Wound and Wound Healing September 2024 5 W H AT I S A W O U N D ? Wounds we create Wound and Wound Healing September 2024 6 HEALING Wound and Wound Healing September 2024 7 HEALING Wound and Wound Healing September 2024 8 HEALING? Wound and Wound Healing September 2024 9 SURGICAL WOUND BREAKDOWN Wound and Wound Healing September 2024 10  S T A G E S O F W O U N D HEALING Divided into 3 overlapping, highly integrated phases (Some texts describe 4 stages as they include haemostasis as a stage)) 1. Inflammation & Debridement i. Haemostasis 2. Proliferation (or repair) 3. Maturation and Remodelling Wound and Wound Healing September 2024 11  S T A G E S O F W O U N D HEALING Microscopic events allow the wound to heal However, we can recognise what stage the wound is at macroscopically Wound and Wound Healing September 2024 12 I N F L A M M AT I O N Wound and Wound Healing September 2024 13  I N F L A M M AT I O N : H A E M O S TA S I S Inflammatory phase starts with haemostasis First few minutes after injury Damage to vessels Blood and lymph escapes Fills the wound Cleansing/prevent further contamination Mast cells Wound and Wound Healing September 2024 14  I N F L A M M AT I O N : H A E M O S TA S I S Reflex vasoconstriction (catehcholamines, serotonin, bradykinin, histamine) First 5-10 min Reduce blood loss Endothelial damage ➔ activates Platelets Platelet plug Then Vasodilation Mast cells release histamine Mast NO leads to vasodilation cells Increase O2, WBCs and Protein to area Endothelial damage➔ exposes Tissue Factor Intrinsic coagulation cascade Fibrinogen → Fibrin Fibrin Plug Wound and Wound Healing September 2024 15  THE BLOOD CLOT Haemostatic plug Barrier to infection Prevents further fluid loss Framework for early wound organisation Provisional ECM binding sites for neutrophils, macrophages and connective tissue cells Minimal wound strength but stabilises wound edges Dries to form scab (eschar) Allows healing to occur underneath (wound micro environment) Eventually sloughs Wound and Wound Healing September 2024 16 I N F L A M M A T I O N & DEBRIDEMENT Wound and Wound Healing September 2024 17  I N F L A M M AT I O N A N D D E B R I D E M E N T Migration of leukocytes into wound Within 6 hours Neutrophils 0 - 48 hrs Destroy bacteria Phagocytose In Toxic oxygen species (NO) Practice Vasodilation Pro-inflammatory mediators [component of pus] Wound and Wound Healing September 2024 18 M I G R AT I O N O F L E U C O C Y T E S I N TO W O U N D Monocytes 48-72 hours Essential for wound healing Transform into activated macrophages Phagocytose/Destroy bacteria Remove clot Debride necrotic tissue by phagocytosis and release enzymes (collagenase) Produce pro-inflammatory mediators Stimulates repair – growth factors fibroplasia angiogenesis Epithelialisation Modify ECM in preparation to become granulation tissue Wound and Wound Healing September 2024 19  G R O S S S I G N S O F I N F L A M M AT I O N Heat, redness, swelling, pain, loss of function Open wound, blood clots, pus/serosanguineous discharge Vasodilation Increased permeability Extravasation of fluid Obstruction of lymphatic channels Stimulation of nerve ending due to pressure, stretching or chemical stimulation (bradykinin) Today’s Veterinary 20 Wound and Wound Healing September 2024 Nurse CHRONIC WOUNDS Wound and Wound Healing September 2024 21 S Y S T E M I C INFLAMMATION Big inflammatory focus Not enough proteins/leukocytes to have inflammatory response in the entire area Prolonged pro-inflammatory phase Persistent inflammatory focus Prolonged pro-inflammatory phase → Systemic Inflammatory Effects (SIRS) Continued vasodilation →Hypotension CVS response (tachycardia, vasoconstriction of non-essential organs= GIT) Barrier of GIT reduced Bacteria translocate into Liver Hepatic inflammation → further systemic inflammation Renal Failure, Hepatic Failure (MODS) Inappropriate Coagulation (DIC) Brain starved of nutrients DEATH Wound and Wound Healing September 2024 22  S U M M A R Y O F T H E I N F L A M M AT I O N A N D D E B R I D E M E N T STAGE Occurs immediately after the wound is created Generally lasts 2-5 days although can be longer Immediate haemostasis (5-10 mins) as platelets form a plug This acts as a barrier to further contamination Later vasodilation occurs Then leucocytes migrate into the wound Neutrophils first, followed by monocytes which become tissue macrophages after 46-96 hours Macrophages stimulate repair by fibroplasia, angiogenesis and epithelialisation Debride necrotic tissue and phagocytose bacteria Wound and Wound Healing September 2024 23 P R O L I F E R A T I O N A N D REPAIR Wound and Wound Healing September 2024 24  P R O L I F E R A T I V E PHASE Restores skin integrity by filling the wound with new tissue Angiogenesis Fibroplasia Epithelisation Granulation Tissue Contraction Wound and Wound Healing September 2024 25  P R O L I F E R A T I O N : FIBROPLASIA Fibroblasts proliferate and migrate into the wound differentiate into myofibroblasts migrate along the ECM synthesise collagen Type I Initially collagen in the wound is Type III Type I collagen is stronger than Type III Once wound is stable fibroblasts stop producing collagen Capillaries regress and granulation tissue becomes a scar Requires oxygen and nutrition Perfusion must be good Wound and Wound Healing September 2024 26  P R O L I F E R A T I O N : ANGIOGENESIS New capillaries form From existing vessels at the wound edges Endothelial cells migrate into the ECM Capillaries are fragile and highly permeable Wound and Wound Healing September 2024 27  P R O L I F E R A T I O N : EPITHELIALISATION Migration of epidermal cells at the margin of the wound Proliferation of epidermal cells behind this leading edges Epidermis can only come from wound margins after granulation tissue has formed New epidermis may be visible 4-5 days after wounding In large wounds may not complete (granulation in the middle) Can be thin and easily traumatised in the middle of large wounds Adnexal structures do not regenerate Pigmentation is variable Wound and Wound Healing September 2024 28  P R O L I F E R A T I O N : EPITHELIALISATION Healing occurs side to side, not top to bottom. Long incisions heal just as fast as short ones. Wound and Wound Healing September 2024 29  P R O L I F E R A T I O N : G R A N U L A T I O N TISSUE Granulation Tissue – combination of new capillaries, fibroblasts, and connective tissue Fills wound beneath the scab/bandage Protects the wound No active dressing needed Barrier to infection No further antibiotics needed Surface for epithelialisation Contains myofibroblasts (help with Contraction) Occurs (transition from ECM) ~4-5 days after injur y Can take weeks to fill a large wound Wound and Wound Healing September 2024 30 P R O L I F E R A T I O N : CONTRACTION Days 5-9 post injury Reduction in wound size Contraction of myofibroblasts Surrounding skin stretches (may look stellate) Can be a problem over joints/body openings loss of function Continues until wound edges meet Negative feedback May cease if tension in surrounding tissue is too high Wound and Wound Healing September 2024 31  S U M M A R Y O F P R O L I F E R A T I V E PHASE Occurs between days 4-21 depending on degree of contamination Fibroblasts enter the wound These can differentiate to myofibroblasts Collagen is formed Angiogenesis/neovascularisation occurs This leads to formation of new epithelium and fibrous tissue This will contract and lead to closure of the wound Wound and Wound Healing September 2024 32  MATURATION/REMODELLING Increases mechanical strength of the wound Reorganization of the connective tissue Rearrangement of collagen bundles - crosslinking Reduction in collagen content Wound and Wound Healing September 2024 33  MATURATION/REMODELLING » Remodelling takes years » Rate of remodelling differs between tissues Wound and Wound Healing September 2024 34  MATURATION/REMODELLING Initial wound strength ➔ sutures, fibrin clot and epithelialisation (weak) » After three to five days, granulation tissue contributes (friable) » After seven to 10 days, collagen and scar tissue present Wound and Wound Healing September 2024 35 W O U N D S T R E N G T H O V E R TIME Wound and Wound Healing September 2024 36 WOUND HEALING PHASES Wound and Wound Healing September 2024 37  S U M M A R Y M A T U R A T I O N REMODELLING Can take 21 days to years Increases the strength of the wound Collagen is remodelled from Type III to Type I collagen Fibroblasts regress as tissue tension decreases Wound and Wound Healing September 2024 38  C L I N I C A L RELEVANCE » To recognise stage of healing at presentation and during management » In order to manage all types of wounds in most efficient manner Should it be dressed/covered Type of dressing Antibiotics Length of treatment Distress, pain to patient, £££ for owner Communication with owners Wound and Wound Healing September 2024 39  CLINICAL RELEVANCE – MANAGING T R A U M A T I C WOUNDS Inflammation Cleaning Debridement (surgical or autolytic) Appropriate dressings Protect from further contamination Antibiotics if infected Proliferation Encourage granulation tissue Granulation tissue no longer requires antibiotics Maturation Fragile and not able to withstand normal forces Wound and Wound Healing September 2024 40  CLINICAL RELEVANCE – HEALING ELECTIVE S U R G I C A L WOUNDS Communicate post op care to owners How strong is the spay wound at suture removal? Can it withstand exercise? A well apposed elective wound passed through phases more quickly Inflammatory phase 0-48 hours Proliferative phase 2-5 days Weak seal in 3-6 hours (protected from contamination but easily pulled apart) Protective covering? Peri-operative antibiotics? Sutures protect the seal Places them away from active healing zone Skin heals more quickly than fascia (linea alba) Wound and Wound Healing September 2024 41 CL INICAL RELEVANCE To understand when and why complications may occur Delayed healing Chronic wounds SIRS = life threatening Wound and Wound Healing September 2024 42  F I R S T D O N O HARM H E A L I N G W I L L OCCUR. » OUR JOB IS FACILITATE AND M A N A G E IT Wound and Wound Healing September 2024 43 W O U N D H E A L I N G OVERVIEW Wound and Wound Healing September 2024 44  FA C T O R S A F F E C T I N G W O U N D H E A L I N G : C AT S V S DOGS 7 days post- skin incision cat wound bursting strength ~ 50% dog Granulation tissue slower to appear in cats (6.3 days) versus dogs (4.5 days) Time to completely cover wound with granulation tissue greater in cats (19 days) than dogs (7.5 days) Removal of subcutaneous tissue dramatically reduced granulation tissue production in both species Wound and Wound Healing September 2024 45  FA C T O R S T H AT A F F E C T W O U N D H E A L I N G – W O U N D FACTORS Type of injury (forces applied) Trauma vs surgery Perfusion, blood supply, tissue viability, haematoma/seroma Contamination Anatomical location Movement, pressure, skin tension/availability Neoplasia Following tumour resections Wound and Wound Healing September 2024 46  FA C T O R S T H AT A F F E C T W O U N D H E A L I N G PAT I E N T FA C T O R S Concurrent trauma Hypovolaemic shock Poor nutritional status Other life threatening injuries Consumption of platelets Pre existing concurrent disease Diabetes mellitus, hypothyroidism, HAC, Infection, anaemia/coagulopathies, uraemia, hypoproteinaemia/poor nutrition, neoplasia) Obesity Current medication Immunosuppressive drugs/chemotherapy Radiation therapy Species Cat vs dog Wound interference Wound and Wound Healing September 2024 47  FA C TO R S T H AT A F F E C T W O U N D H E A L I N G – S U R G E O N FACTORS Technique Appropriate debridement, choice of lavage solution or open wound management Halsted’s principles (meticulous haemostasis, obliteration of dead space, tension free apposition of tissues Judicious and appropriate use of anti-microbials Avoiding prolonged anaesthesia and keeping surgical time as short as possible Decision-making in wound treatment Manage open vs closed Type of closure Wound and Wound Healing September 2024 48 FASCIA Slow healing – not many blood vessels No strength from healing tissue for 1 – 2 weeks (just sutures) Active zone up to 2 mm away from wound Sutures should be ~3 mm away from wound edge to be secure Wound and Wound Healing September 2024 49  GASTROINTESTINAL TRACT Anastomosis bursting strength decreases over first 48 hours weakened tissue during inflammatory phase of healing allows dehiscence (peristalsis) lag phase; 3-5 days post surgery Pre-existing septic peritonitis: less suture-holding capacity Already weakened at time of surgery Perfusion to anastomosis site is key CARE with drugs-NSAIDS Can delay healing These patients often have hypoproteinaemia Wound and Wound Healing September 2024 50  D E C I S I O N M A K I N G W I T H A WOUND? Can we attempt primary closure? Can we apply Halsted’s principles? Would healing by granulation be a better option? Good communication with the owner is imperative Wound and Wound Healing September 2024 51  W H A T A R E H A L S T E A D ’ S PRINCIPLES? 1.Gentle tissue handling 2.Meticulous control of haemorrhage 3.Strict asepsis 4.Elimination of dead space 5.Accurate tissue apposition 6.Minimal tension Wound and Wound Healing September 2024 52  W H AT FA C T O R S S H O U L D W E C O N S I D E R W H E N F A C E D W I T H A WOUND? Does the patient have underlying disease conditions that could affect healing? Is it on any drugs that could affect healing? How long ago did this wound occur? (Golden period up to 6 hours) Was there blunt trauma? Was there a sharp penetration? Wound and Wound Healing September 2024 53  W H AT W O U L D L E A D YO U TO C O N S I D E R D E L A Y E D CLOSURE? Long time since wounding, >6 hrs/golden period Presence of gross contamination or infection Presence of necrotic tissue/devitalised/disrupted blood supply to skin edges/crushing injury Excessive tension on surrounding skin with attempted closure Excessive skin defect/degloving Wound and Wound Healing September 2024 54  W H Y I S B L O O D S U P P L Y S O IMPORTANT? Preservation of blood supply brings oxygen and leucocytes to the wound The leucocytes( neutrophils, monocytes, T-Cells, B-Cells, platelets support tissue macrophages Tissue macrophages are essential for the inflammatory response Provides acute phase proteins such as complement and antibodies which combat infection The fluid provides a medium for inflammatory cells to operate Maintains glucose delivery and metabolic waste product removal Allows the systemic response to inflammation such as hyperthermia Wound and Wound Healing September 2024 55 RERERENCES Wound and Wound Healing September 2024 56