logging in or signing up burns seminar gaiech Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT lite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: Embed: Flash iPad Copy Does not support media & animations WordPress Embed Customize Embed URL: Copy Thumbnail: Copy The presentation is successfully added In Your Favorites. Views: 2394 Category: Science & Tech.. License: All Rights Reserved Like it (0) Dislike it (0) Added: October 15, 2010 This Presentation is Public Favorites: 2 Presentation Description No description available. Comments Posting comment... Premium member Presentation Transcript SUBJECT SEMINARBURNS : SUBJECT SEMINARBURNS CHAIRPERSON : DR.M.A.BALAKRISHNA PRESENTOR : DR.K.P.S.VINAYAKHRAM HISTORY…….. : HISTORY…….. Burns injuries were first described in the Ebers papyrus (1500 B.C.) Dupuytren, the famous 19th century French surgeon who first described the contracture that bears his name wrote: ‘Burns had been the object of one of the most bizarre treatment methods’. Fabricius Hildanus, a 15th century German physician,was the first to classify burns into three degrees Slide 3: After the First World War the best treatment for burns was surgical skin transplantation with subsequent scar reduction and pain control medications as needed. In 1960 s treatment protocol for surgical burns therapy consisting of localized treatment and systemic medical management. The localized treatment was typified by a drying of the burned skin which enabled a crust (deep, partial-thickness) or eschar (full-thickness) to develop over the burned tissue. This crusting was accompanied by surgical excision of necrotic skin tissues and of viable dermis (tangential excision of crust). Slide 4: In addition, whole subcutaneous tissue (fascial debridement of eschar) was also an all too frequent aspect of the treatment. After this debridement was achieved, autografts or cultured epithelial autografts were placed on top of the lesion to close the wound from exogenous infectious agents. In the 1970s the Chinese established an entirely new theory of burns physiology upon which they built a dramatically effective burns treatment which they called ‘Burns Regenerative Therapy’ (BRT). This innovation, which integrates moist-exposed burns treatment (MEBT) and moist-exposed burns ointment (MEBO), was a balm to the struggling burns therapy industry. Slide 5: The therapeutic essence of MEBT/MEBO is to maintain the burns wound in an optimum physiologically moist environment through the use of a specially designed ointment – MEBO. MEBO serves as an analgesic , anti-shock,anti-bacterial,promotes epithelial repair and reduces scar formation. Anatomy & Physiology of the Skin : Anatomy & Physiology of the Skin Layers Epidermis Dermis Subcutaneous Underlying Structures Fascia Nerves Tendons Ligaments Muscles Organs Functions of the Skin : Functions of the Skin Protection from infection Sensory organ Temperature Touch Pain Controls loss and movement of fluids Temperature regulation Insulation from trauma Flexible to accommodate free body movement BURNS : BURNS Burns is defined as a wound in which there is coagulative necrosis of the tissue. Types of Burn Injury : Types of Burn Injury Thermal burns: flame, flash, contact with hot objects. Scald burns: hot fluids. Chemical burns: necrotizing substances (acids, alkali). Electrical burns: intense heat from an electrical current Smoke & inhalation injury: inhaling hot air or noxious chemicals Cold thermal injury: frostbite. Thermal Burns : Thermal Burns Heat changes the molecular structure of tissue Causing Denaturion of proteins Extent of burn damage depends on Temperature of agent Amount of heat Duration of contact Slide 11: The effects of the burns are influenced by the: 1.Intensity of the energy 2.duration of exposure 3.type of tissue injured Pathophysiology of Burns : Pathophysiology of Burns Fluid Shift Period of inflammatory response Vessels adjacent to burn injury dilate → ↑ capillary hydrostatic pressure and ↑ capillary permeability Continuous leak of plasma from intravascular space into interstitial space Associated imbalances of fluids, electrolytes and acid-base occur Hemoconcentration Lasts 24-36 hours Slide 13: Fluid remobilization Capillary leak ceases and fluid shifts back into the circulation Restores fluid balance and renal perfusion Increased urine formation and diuresis Continued electrolyte imbalances Hyponatremia Hypokalemia Hemodilution SYSTEMIC CHANGES : SYSTEMIC CHANGES Cardiac Decreased cardiac output Pulmonary Respiratory insufficiency as a secondary process Can progress to respiratory failure Aggressive pulmonary toilet and oxygenation Gastrointestinal Decreased or absent motility (may need NG tube) Curling’s ulcer formation Slide 15: Metabolic Hypermetabolic state Increased oxygen and calorie requirements Increase in core body temperature Immunologic Loss of protective barrier Increased risk of infection Suppression of humoral and cell-mediated immune responses Slide 16: stress mineralocorticoid release retention of Na,Cl, and water with excretion of Potassium Alteration in capillary permeablity allowing egress of electrolytes and proteins from the vascular compartment ACUTE PHASE : ACUTE PHASE Clinical shock External loss of plasma Loss of circulating red cells Burn edema SUB ACUTE PHASE : SUB ACUTE PHASE Diuresis Clinical Anemia Accelerated metabolic rate Nitrogen Disequilibrium Disordered Fat metabolismn Abnormal vitamin metabolism Impaired Hepatic Function Slide 19: Bone and joint changes Endocrine Disturbances Electrolyte and chemical imbalance Circulatory Derangements Loss of of function of skin as an organ Body’s Response to Burns : Body’s Response to Burns Emergent Phase (Stage 1) Pain response Catecholamine release Tachycardia, Tachypnea, Mild Hypertension, Mild Anxiety Fluid Shift Phase (Stage 2) Length 18-24 hours Begins after Emergent Phase Reaches peak in 6-8 hours Damaged cells initiate inflammatory response Increased blood flow to cells Shift of fluid from intravascular to extravascular space MASSIVE EDEMA Slide 21: Hypermetabolic Phase (Stage 3) Last for days to weeks Large increase in the body’s need for nutrients as it repairs itself Resolution Phase (Stage 4) Scar formation General rehabilitation and progression to normal function Jackson’s Theory of Thermal Wounds : Jackson’s Theory of Thermal Wounds Jackson’s Theory of Thermal Wounds Zone of Coagulation Area in a burn nearest the heat source that suffers the most damage as evidenced by clotted blood and thrombosed blood vessels Zone of Stasis Area surrounding zone of coagulation characterized by decreased blood flow. Zone of Hyperemia Peripheral area around burn that has an increased blood flow Classification of Burn Injury : Classification of Burn Injury Severity is determined by: depth of burn extend of burn calculated in percent of total body surface (TBSA) location of burn patient risk factors Depth of Burns : Depth of Burns Medicolegal Classification Clinical classification CLASSIFICATION OF BURNS : CLASSIFICATION OF BURNS Slide 27: DUPUYTREN S CLASSIFICATION WILSON CLASSIFICATON Superficial Burn : 1st Degree Burn : Superficial Burn : 1st Degree Burn Reddened skin Pain at burn site Involves only epidermis Partial-Thickness Burn: 2nd Degree Burn : Partial-Thickness Burn: 2nd Degree Burn Intense pain White to red skin Blisters Involves epidermis & dermis Full-Thickness Burn:3rd Degree Burn : Full-Thickness Burn:3rd Degree Burn Dry, leathery skin (white, dark brown, or charred) Loss of sensation (little pain) All dermal layers/tissue may be involved ASSESSMENT OF BURNS : ASSESSMENT OF BURNS Rule of Nine Best used for large surface areas Expedient tool to measure extent of burn Rule of Palms Best used for burns < 10% BSA Lund-Browder Chart : Lund-Browder Chart Location of Burns : Location of Burns Vital organs of burn: Face, neck Chest Perineum Hand Joint regions Other areas Patient risk factors… : Patient risk factors… Associated trauma Inhalation injuries Circumferential burns Electricity Age (young or old) Pre-existing disease Abuse Classification of Burns Severity : Classification of Burns Severity Slide 39: Clinical evaluation,– Accuracy of 50% only Investigational methods – Vital dyes, flourescein fluorometry, US, thermography, light reflectance, laser doppler, MRI. Methods detect cell death, blood flow, edema Systemic Complications : Systemic Complications Hypothermia Disruption of skin and its ability to thermoregulate Hypovolemia Shift in proteins, fluids, and electrolytes to the burned tissue General electrolyte imbalance Eschar Hard, leathery product of a deep full thickness burn Dead and denatured skin Assessment of Thermal BurnsGeneral Signs & Symptoms : Assessment of Thermal BurnsGeneral Signs & Symptoms Pain Changes in skin condition at affected site Adventitious sounds Blisters Sloughing of skin Hoarseness Dysphagia Dysphasia Burnt hair Edema Paresthesia Hemorrhage Other soft tissue injury Musculoskeletal injury Dyspnea Chest pain Assessment of Thermal Burns : Assessment of Thermal Burns Any partial or full thickness burn involving hands, feet, joints, face, or genitalia >30% BSA Partial Thickness Inhalation Injury >10% BSA Full Thickness Critical >2% BSA Full Thickness >50% BSA Superficial <2% BSA Full Thickness <15% BSA Partial Thickness <50% BSA Superficial >15% BSA Partial Thickness Moderate Minor Burn Severity MANAGEMENT OF BURNS : MANAGEMENT OF BURNS Pre-hospital Care : Pre-hospital Care Remove from area! Stop the burn! If thermal burn is large--FOCUS on the ABC’s A=airway-check for patency, soot around nares, or signed nasal hair B=breathing- check for adequacy of ventilation C=circulation-check for presence and regularity of pulses Slide 45: Burn too large--don’t immerse in water due to extensive heat loss Never pack in ice Pt. should be wrapped in dry clean material to decrease contamination of wound and increase warmth Effects of burn injury : Effects of burn injury Local - Tissue damage - Inflammation - Infection 2- Regional - Circulation problem 3- Systemic - Fluid loss - Multi-organ failure Slide 47: Airway Breathing Circulation Disability Exposure 3 Phases of Burn Management : 3 Phases of Burn Management Emergent/Resuscitative First 48 hours Acute Approximately 48 hours after injury to complete wound closure Rehabilitative Begins with wound closure and ends when client returns to highest possible level of functioning Emergent Phase (Resuscitative Phase) : Emergent Phase (Resuscitative Phase) Lasts from onset to 5 or more days but usually lasts 24-48 hours begins with fluid loss and edema formation and continues until fluid motorization and diuresis begins Greatest initial threat is hypovolemic shock to a major burn patient! Slide 50: Airway management-early nasotracheal or endotracheal intubation before airway is actually compromised (usually 1-2 hours after burn) Ventilator/ ABGs 6-12 hours later: Bronchoscopy to assess lower respiratory tact chest physiotherapy, suction SEDATION : SEDATION Burns is a very painful condition. Sedation not only helps in relieving pain but can also be useful in shock. Intravenous route is preferred in an absolute minimum dose which ensures rapid and predictable concentration. It should be given for 4-5 days but the dosage can be markedly reduced in 48hrs. Usually morphine is preferred in adults and barbiturates in childrens. Smoke Inhalation Injury : Smoke Inhalation Injury Responsible for most deaths Evolution may require several days Exposure of airways and lungs to toxic chemicals Tracheobronchitis, epithelial fibrin casts Airway obstruction, PMN activation with release of oxygen radicals, proteases Pulmonary edema within 2-3 days Slide 54: Physical findings may be suggestive (carbonaceous sputum, singed vibrissae, facial edema, stridor) Bronchoscopy allows direct visualization When combined with xenon scan 93% accuracy TREATMENT : TREATMENT High frequency percussive jet ventilation reduces airway pressures and improves survival. Bronchodilators. Nebulized Heparin. Hypertonic Saline. Racemic Epinephrine. Slide 57: Complications during emergent phase of burn injury are 3 major organ systems... Cardiovascular Respiratory Renal systems Fluid Resuscitation : Fluid Resuscitation Hypovolemia was major cause of death Massive transudation of fluids from vessels due to increased permeability Edema intensifies over 8-48 hours Goal: preservation of organ perfusion and urine output Rapid resuscitation in children (1/2 over 4 hours) may be preferred ABA Recommendations : ABA Recommendations Guidelines Burns > 20% TBSA require fluid resuscitation(C) Common formulas 2-4 ml/kg/%TBSA/24 hrs (C) Titrate to UO of 0.5-1.0 ml/kg (1-1.5 in kids) (C) Add maintenance fluids in kids Fluid Resuscutaion : Fluid Resuscutaion Many different formulas Crystalloids preferred over colloids during first 12-24 hours Assessment of adequacy of fluid replacement : Assessment of adequacy of fluid replacement Urine output is most commonly used parameter Urine osmolarity is the most accurate parameter UOP = U/O > 0.5-1.0 ml/kg/hr CVP 5-10 cm/H2O. Fluid Resuscitation Complications : Fluid Resuscitation Complications Overresuscitation complications: Poor tissue perfusion Compartment syndrome Pulmonary edema Pleural effusion Electrolyte abnormalities Fluid Creep : Fluid Creep First described by Pruitt. Excessive fluid resuscitation in the belief that more is better. Consequences may be life threatening. Modified Brooke formula, (2 ml/kg/%burn) with lower initial volume preferred. Slide 65: Overestimation of burn size common Hesitancy to reduce fluid rates with adequate UO Opioid creep leading to vasodilatation Higher likelihood with more severe burns (>80% TBSA) Abdominal compartmentsyndrome : Abdominal compartmentsyndrome Risk increased by high infusion rates – > 0.25 L/kg Risk lowered by use of colloids after 12-24 hr Slide 67: Addition of colloids, especially after 12-24hrs decreases volume requirements Oral resuscitation in alert, moderate sized burns Hypertonic saline only by experienced, with close monitoring of Na+ Plasma exchange as salvage procedure Nutritional Therapy : Nutritional Therapy Burn patients need more calories & failure to provide will lead to delayed wound healing and malnutrition. Slide 70: SUTHERLAND FORMULA DAVIES FORMULA PROTEIN NEEDS WOUND MANAGEMENT : WOUND MANAGEMENT Escharotomy / Fasciotomy Escharectomy + homograft Dressing / hydrotherapy Debridement Application of autograft Splinting PB contractures management Positioning of burn patient : Positioning of burn patient Aim : To prevent contracture Head and neck- Extended (no pillow) Eyelids - apply eye ointment 3 times daily Lips – apply moisturizing agent (Vaseline) Lip commissure – apply maintainer Hand – elevation and apply splint in functional position Axilla (abducted ) , knee (extended) Foot- dorsiflexed with foot support Circumferential burn : Circumferential burn Limb is burned all the way around. Soft tissues under the skin always swell with burns (due to capillary leak of fluids in first day or so). There is a loss of skin expansion due to the loss of turgor/elasticity in burned tissue Pressure inside limb gradually increases. Eventually, pressure inside limb exceeds arterial pressure occluding blood supply. This requires escharotomy to relieve the pressure. Escharotomy : Escharotomy Eschar is a dry scab or slough formed on the skin as a result of a burn or by the action of corrosive or caustic substance Escharotomy = cut burned skin to relieve underlying pressure Cut along inside and outside of limb from good skin to good skin Knife can be used, or cautery. Escharotomy : Escharotomy Indications Circulation to distal limb is in danger due to swelling. Progressive loss of sensation / motion in hand / foot. Progressive loss of pulses in the distal extremity by palpation or doppler. In circumferential chest burn, patient might not be able to expand his chest enough to ventilate, and might need escharotomy of the skin of the chest Escharotomy : Escharotomy Incise along medial and/or lateral surfaces. Avoid bony prominences. Avoid tendons, nerves, major vessels. Fasciotomy : Fasciotomy Fascia = thick white covering of muscles. Fasciotomy = fascia is incised (and often overlying skin) Skin and fascia split open due to underlying swelling. Blood flow to distal limb is improved. Muscle can be inspected for viability. Debridement : Debridement Types of debridement: 1. Auto debridement. 2. Tangential excision (at the end of 1st week) 3. Staged primary debridement (1-3 days post burn). This early debridement of dead tissue interrupts and attenuates the systemic inflammatory response and normalize immune function. 4. For deep circumferential burn, urgent escharotomy is done BLISTERS : BLISTERS Intact blister barrier to microbial invasion Intact blister creates moist environment hence more rapid reepithelialization More rapid angiogenesis Rupture of blisters under contaminated conditions may increase infection rates BLISTERS : BLISTERS In the pre-hospital setting, there is no hurry to remove blisters. Leaving the blister intact initially is less painful and requires fewer dressing changes. The blister will either break on its own, or the fluid will be resorbed. Before and after debridement : Before and after debridement Dressings : Dressings Standard Multiple gauze layers over topical agent or antibiotic Biologic Homograft (allograft) from cadaver Heterograft (xenograft) from animal (pig) Amniotic membrane Cultured skin Artificial skin Two-layer product which creates an artificial dermis Synthetic dressing Solid silicone and plastic membrane Can see through to monitor wound status DRESSING : DRESSING Exposure method Closed method TEMPORARY COVERAGE MATERIALS : TEMPORARY COVERAGE MATERIALS These are two categories: 1. Biologic.2. Bio-engineered. Advantages of biological cover: 1. They maintain clean wound environment until skin grafting achieved or the wound get epithelized if it is partial in thickness. 2. They reduce heat and fluid loss. 3. They reduce pain. 4. Allow early mobilization by protecting the nerve endings. BIOLOGIC COVERINGS : BIOLOGIC COVERINGS Opsite Biobrane Transcyte Integra BIO-ENGINEERED : BIO-ENGINEERED Xenograft ( Pig Skin) Allograft ( Homograft,cadaver skin) Occlusive dressings : Occlusive dressings May speed healing. Enhanced epithelialization and angiogenesis. Pain reduction (reduced dressing changes). Improved cosmesis. Fluid collections common and should be drained. Occlusive therapy does not increase infection rates. Duoderm and Biobrane result in faster healing and less pain than silver sulfadiazine. Hydrocolloid dressing (Duoderm) : Hydrocolloid dressing (Duoderm) Artificial Skin : Artificial Skin Yannas and Bruke “Pioneers of Artificial Skin” Complex of collagen and condroiton sulphuric acid with silicon membrane How it Works : How it Works Artificial skin is secured over wound during surgery The skin remains in place for several weeks and allows new tissue to grow in to bottom matrix layer Top layer provides protection from infection and dehydration Benefits : Benefits 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 Topical Antibiotics : Topical Antibiotics MEBO Dressing : MEBO Dressing TETANUS PROPHYLAXIS : TETANUS PROPHYLAXIS 0.5 ml Tetanus toxoid given through intramuscular route. In case of absence of active immunisation within 10yrs 250 units of tetanus immunoglobbulin should be administered. GASTRIC DECOMPRESSION : GASTRIC DECOMPRESSION Reflex Paralytic ileus in the first 24hrs. Intestinal motility is gradually lost in the first 12hrs of burn injury. Nasogasric tube insertion helps not only to decompress the stomach and proximal intestine but also to instill h2 blockers like cimetidine (400mg 4th hourly ) to prevent stress induced hemorrhagic gastritis. Burn Excision & Grafting : Burn Excision & Grafting Early excision & grafting improves burn patient mortality & functional outcome Initial excision should occur soon after resuscitation Full-thickness skin grafts (FTSG) Split-thickness skin grafts (STSG) Human allograft Porcine xenograft Dermal substitutes: Integra Excision and Grafting : Excision and Grafting POST-OPERATIVE CARE : POST-OPERATIVE CARE Because of the lack of glandular tissue, graft has tendency to dry. Therefore must be moitsturized with thick moisturizing cream at least 3 times daily. Local & Minor Burns : Local & Minor Burns Local cooling Partial thickness: <15% of BSA Full thickness: <2% BSA Remove clothing Cool or Cold water immersion Consider analgesics Moderate to Severe Burns : Moderate to Severe Burns Dry sterile dressings Partial thickness: >15% BSA Full thickness: >5% BSA Maintain warmth Prevent hypothermia Consider aggressive fluid therapy Moderate to severe burns Burns over IV sites Place IV in partial thickness burn site. Moderate to Severe Burns : Moderate to Severe Burns Caution for fluid overload Frequent auscultation of breath sounds Consider analgesic for pain Morphine Nubain Prevent infection COMPLICATIONS OF BURNS : COMPLICATIONS OF BURNS Curlings ulcer Acute Pancreatitis Acute Acaculous Cholecystitis Superior Mesentric Artery syndrome Non-Occlusive Ischaemic Enterocolitis Myocardial infarction Rehabilitative Phase : Rehabilitative Phase Emphasis: Psychological adjustment of client Prevention of scars and contractures Resumption of pre-burn activity Work Family Social GOAL OF PHYSIOTHERAPY : GOAL OF PHYSIOTHERAPY 1. Prevent, minimize or correct deformity. 2. Protect weak muscles from over stretching. 3. Maintain range of motion. 4. Provide positional function. 5. Protect any exposed joints or tendons. 6. Provide immobilization across joints after grafting. 7. Minimize scarring with pressure garment. 8. Develop functional skills Indications for Admission : Indications for Admission Adults > 15% 2° Children > 10% 2° 3° burns > 2% Face, hands, feet, perineum Serious underlying diseases Social considerations Long Term Complications : Long Term Complications Hypertrophic scarring, keloids, contractures Social and employment dysfunction Hyperpigmentation Most burn patients need follow up with specialist to consider rehabilitation Hypertrophic Scarring and Hyperpigmentation : Hypertrophic Scarring and Hyperpigmentation Flame : Flame Remove the person from the source of the heat. b. If clothes are burning, make the person lie down to keep smoke away from their face. c. Use water, blanket or roll the person on the ground to smother the flames. d. Once the burning has stopped, remove the clothing. e. Manage the persons airway, as anyone with a flame burn should be considered to have an inhalation injury SCALDS : SCALDS Scalding-typically result from hot water, grease, oil or tar. Immersion scalds tend to be worse than spills, because the contact with the hot solution is longer. They tend to be deep and severe and should be evaluated by a physician. Cooking oil or tar (especially from the “mother pot”) tends to be full- thickness requiring prolonged medical care. TREATMENT : TREATMENT Remove the person from the heat source. Remove any wet clothing which is retaining heat. With tar burns, after cooling, the tar should be removed by repeated applications of petroleum ointment and dressing every 2 hours. Chemical Burns : Chemical Burns Acids • Protein injury by hydrolysis. • Thermal injury is made with skin contact. Alkali • Saponification of fat • Hygroscopic effect- dehydrates cells • Dissolves proteins by creation of alkaline proteinates (hydroxide ions) Electrical Burns : Electrical Burns Greatest heat occurs at the points of resistance Entrance and Exit wounds Dry skin = Greater resistance Wet Skin = Less resistance Longer the contact, the greater the potential of injury Increased damage inside body Smaller the point of contact, the more concentrated the energy, the greater the injury. Slide 121: Electrical Current Flow Tissue of Less Resistance Blood vessels Nerve Tissue of Greater Resistance Muscle Bone Results in……….. : Results in……….. Serious vascular and nervous injury Immobilization of muscles Flash burns Late complications: cataracts, progressive demyelinating neurologic loss Slide 123: Assess patient Entrance & Exit wounds Remove clothing, jewelry, and leather items Treat any visible injuries Thermal burns ECG monitoring Bradycardia, Tachycardia, VF or Asystole Treat cardiac & respiratory arrest Aggressive airway, ventilation, and circulatory management. Consider Fluid bolus for serious burns 20 ml/kg Consider Sodium Bicarbonate: 1 mEq/kg Consider Mannitol: 10 g REFERENCES : REFERENCES BAILEY AND LOVE S SHORT PRACTICE OF SURGERY 25TH EDITION SABISTONS TEXTBOOK OF SURGERY 18TH EDITION SCHWARTZ S PRINCIPLES OF SURGERY 9TH EDITION A CONCISE TEXTBOOK OF SURGERY BY S.DAS 5TH EDITION CLINICAL AND PATHOLOGICAL ASPECTS OF FORENSIC MEDICINE ; JASON PAYNE JAMES,ANTHONY BUSUTTIL,WILLIAM S SMOCK. AMERICAN BURN ASSOCIAION ; BURN CARE SERVICES IN NORTH AMERICA COMMITTEE ON ORGANISATION AND DELIVERY OF BURN CARE ; 1985 7.BAXTER C.R. 1974 FLUID VOLUME AND ELECTROLYTE CHANGES IN THE EARLY POST BURN PERIOD , CLINICAL PLASTIC SURGERY ,1693 ESSENTIALS OF FORENSIC MEDICINE AND TOXICOLOGY ; DR.K.S.NARAYANA REDDY Thank You…… : Thank You…… You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.