Thermal Injury 2.pdf

Thermal Injury Rawand M.Hawezy Consultant Surgeon Assist.Professor in General Surgery MD, MSc (General Surgery) MRCS(Ireland),MRCPS(Glasgow),FRCS(UK),FACS(USA) College of Medicine Hawler Medical University...

Thermal Injury Rawand M.Hawezy Consultant Surgeon Assist.Professor in General Surgery MD, MSc (General Surgery) MRCS(Ireland),MRCPS(Glasgow),FRCS(UK),FACS(USA) College of Medicine Hawler Medical University e.mail:[email protected] The function and structure of the Skin The skin –the interface between humans and their environment Is the largest organ in the body It weighs an average of 4 kg Covers an area of 2 m2 Composed of 2 main layers (Epidermis & Derms) Epidermis consist of 4 types of cell(BPGH) Derms consists of 2 parts- papillary and Reticular Note: Zone of coagulation— This zone nearest the heat source is the primary injury. It occurs at the point of maximum damage. In this zone there is irreversible tissue loss (necrosis) due to coagulation of the constituent proteins. Zone of stasis—The surrounding zone of stasis is characterized by decreased tissue perfusion. The tissue in this zone is potentially salvageable. The main aim of burns resuscitation is to increase tissue perfusion here and prevent any damage becoming irreversible (if managed well, this zone can turn into a zone of hyperemia and heal). Additional insults—such as prolonged hypotension, infection, or oedema—can convert this zone into an area of complete tissue loss (it can turn into zone of coagulation, if not properly treated) Focus of management Zone of hyperemia—In this outermost zone tissue perfusion is increased. The tissue here will invariably recover unless there is severe sepsis or prolonged hypoperfusion. These three zones of a burn are three dimensional, and loss of tissue in the zone of stasis will lead to the wound deepening as well as widening. The function and structure of the Skin cont’d Functions of Skin: ▪ Protection (against microbs,chemicals,..) ▪ Prevent lose of water &electrolyte. ▪ Shock absorber, insulation, calory reserve. ▪ Temperature regulation. ▪ Sensation (specialized nerve endings). ▪ Lubrication. ▪ Vitamin D synthesis. ▪ Psychosocial, display.  Definition: Burn is a coagulation necrosis of the skin. The incidence of burn injury varies greatly between cultures. Aetiology ▪ Scalds (mostly children, kettles,pans,hot drinks) ▪ Flammable liquids, matches(mostly adolescence) ▪ Flame burns(in adults) ▪ Electrical injury ▪ Chemical (note: needs irrigation and should be admitted ▪ Cold and radiation(rare causes) (note: “cold is the same as heat”; can lead to coagulation and necrosis of tissue) ▪ Drugs ▪ Immunological reaction(TEN) ▪ Mental disease(attempted suicide or assault) The Pathophysiology of Burn Injury ▪ Most common organ affected is the skin ▪ Can damage the airways and lungs ▪ Physical burn injury to the airway above the larynx ▪ Physical burn injury to the airways below the larynx ▪ Metabolic poisoning ▪ Inflammation and circulatory changes (note: edema can result from endothelial damage (capillary leak syndrome), which leads to fluid loss and subsequent shock) ▪ The immune system and infection The Pathophysiology of Burn Injury ▪ Changes to the intestine Note: affects the GIT, especially the stomach (curling ulcers, occur due to ischemia from hypoperfusion) PPI and resuscitation Note: paralytic ileus can result NPO, NG tube for 24 hours Translocation of bacteria can occur and lead to sepsis. Resuscitation and enteral feeding help to prevent this. ▪ Effects of Eschar(around the lung, limbs) ▪ Note: especially important if circumferential ▪ Neck: airway obstruction ▪ Chest: cant expand ▪ Limbs: compartment syndrome ▪ Treatment: Escharotomy, no anesthesia (In the severely burned patient who is obtunded and intubated, no anesthesia is required because the eschar is nonviable tissue with complete destruction of nerve endings) Note: burns can indirectly affect other organs as well, e.g., inhalation (can cause two types of injury, direct effect which causes burning of airways (suspect if there is change of voice, swollen and burned tongue) and indirectly through CO poisoning) Clinical feature Pain Note: although classically grade 3 burns are said to be painless because of the loss of nerve endings, this only applies to the central zone of necrosis, while the stasis and hyperemic zones cause significant pain (??) Note: managed by opiates, NOT NSAIDS, as the latter are harmful to the GIT (??) Hypovolemic shock (note: due to fluid exudation; occurs in major burns) Inhalational injury (note: may need airway management) Classifications of Burn ▪ Classical classification: ▪ First degree (note: epidermis only; not included in management calculations) ▪ Second degree (note: two types – superficial, which involves epidermis and superficial papillary dermis; and deep, which involves epidermis and reticular dermis, hence involving most of the dermis) ▪ Third degree burns (note; all layers, epidermis, dermis and subcutaneous tissue) ▪ Note: fourth degree burns, Involve structures beneath subcutaneous fat, including muscles and bone. ▪ Other classifications: ▪ Partial-thickness burns (PTB) ▪ Superficial (note: papillary dermis) ▪ Deep (note: reticular dermis) ▪ Full-thickness burns (FTB) Note: superficial second-degree burns as there are blisters, which are not seen in deep second-degree burns Note: superficial partial thickness burns Red, pink, shiny, capillary refill and blanching positive (should be sterile; press to blanch and release, capillary refill should be immediate), touch and pinprick sensations are intact. Easy to treat, heals within 5-7 days with little or no scarring Dressing and analgesia. Note: deep partial thickness burns Deep partial thickness burns may demonstrate pallor or mottling, and will not blanch as easily. It has a slower capillary refill if present. Patient has blunting of pinprick sensation (touch still intact?) requires 2 weeks or longer to heal and requires an aggressive treatment to prevent hypertrophic scarring Doesn’t require grafting; as long as infection can be prevented (can lead to scarring) (??) Note: Full thickness burns Full-thickness burns are white, gray, or black, and do not turn pale when touched (Dr. Rawand: early on, it’s white, later becomes black; doesn’t heal by reepithelialization [Eschar]) Requires surgical treatment Small wounds heal by secondary intention and contraction.  The BURN WOUND Necrotic cells and denaturated proteins Release of inflammatory mediators Local and systemic response Note: for IV fluid amount Note: measure urine output Note: e.g., tension pneumothorax EMSB Emergency Management of Severe Burns ATLS trauma principles modified for burn/inhalation injury Primary survey + treat life-threatening injuries Secondary survey Transfer to appropriate facility Prehospital Management Remove source of heat (note: mere seconds can drastically change the prognosis, e.g., partial thickness vs full thickness burn or a much larger BSA) Note: with electrical injury, try to turn off the source of electricity ABC Cool (if burn is localised) Ambulance ‘gel’ dressings are designed for 15 minute use Evacuate to the nearest A+E department Appropriate transport (note: resuscitate first) Exclude concomitant trauma A&E Department Airway Note – effects on airway: circumferential eschar, inhalation injury Including C-Spine control Assessment by appropriate person Anaesthetic SpR or higher Experience of burnt airways Early intubation May be very difficult C-Spine immobilisation  Upper Airway Obstruction Risk Factors Burns around nose /mouth Increasing Soot in nostrils or singed nasal hair risk Burns of tongue upper Intra oral swelling airway Hoarse voice obstruction Oedema on Laryngoscopy Stridor Risk Factors for Inhalation Injury Two or more = Smoke inhalation History of fire in enclosed space (note: suicide attempt by burning one’s self) Carbonaceous sputum Perioral burn Altered level of conciousness Symptoms / signs respiratory distress Hoarseness / loss of voice / stridor Carboxyhaemoglobin > 15% Impaired gas exchange Inhalation Injury Diagnosis Clinical suspicion (note: mostly) Blood gases Chest X ray Bronchoscopy (note: can also be therapeutic, e.g., irrigation, administering medication, removing debris and sputum) CO Note: Carbon monoxide (CO) is a colorless, odorless, tasteless gas. Note: causes displacement of oxygen from hemoglobin because CO has greater affinity for hemoglobin than does oxygen binds Hb 240 greater affinity than oxygen Decreases oxygen carrying capacity of blood – anoxia Binds intracellular cytochromes – sick cell syndrome (intracellular cytochrome electron carrying chain may be affected) Half life 250 minutes breathing room air Half life 40 minutes breathing 100% oxygen Note - treatment: immediately take the patient outside; 100% O2 to washout the CO Carbon monoxide intoxication 0 -15 % - no symptoms 15 -20 % headache, confusion 20 – 40% nausea, fatigue, disorientation, irritability 40 -60 % - hallucination, ataxia, syncope, convulsions, coma > 60% - death A&E Department Breathing 100 % Oxygen via reservoir mask Nebulised salbutamol as needed Exclude chest wall trauma/pneumothorax Escharotomies if compliance high (note: e.g., chest and neck escharotomy) A&E Department Circulation If shocked, look for causes other than burn! Note: shock may occur due to exudation of fluid 2 x 14g cannulae – through burn is OK (note: as long as it’s not a full thickness burn) Note: other options include venesection and central lines Avoid repeated attempts at central access Treat hypotension empirically Start a burn resuscitation fluid regime In addition to maintenance and resus fluids Backdate to time of burn Note: best fluid is ringer’s lactate; it counteracts the metabolic acidosis and also approximates plasma composition A&E Department Disability Accurate GCS and history Suspect head injury Document all neurological abnormalities Patients may be ventilated for weeks Legal considerations A&E Department Exposure …and environmental control (note: these patients lose thermoregulation and feel cold; room temperature should be increased) Estimate burn size – rule of 9s Cover burn with Clingfilm Escharotomies if needed – but consider blood loss KEEP WARM – blankets and hot air blowers Burn Size % Total Body Surface Area Rules Nines (Tens) Lund and Browder Chart Patients hand = 1% TBSA ASSESSMENT OF THE BURN WOUND Assessing size: ▪ The patient’s whole hand is 1% TBSA(for small size burns) ▪ The rule of nines is adequate for a first approximation only (note: for adults only; The rule is not applicable to children, whose body proportions change with age. For children, use the Lund and Browder chart) ▪ The Lund and Browder chart is useful in larger burns Note: (Wallace) Rule of Nines The Rule of Nines estimation of body surface area burned is based on assigning percentages to different body areas. The entire head is estimated as 9% (4.5% for anterior and posterior). The entire trunk is estimated at 36% and can be further broken down into 18% for anterior components and 18% for the back. The anterior aspect of the trunk can further be divided into chest (9%) and abdomen (9%). The upper extremities total 18% and thus 9% for each upper extremity. Each upper extremity can further be divided into anterior (4.5%) and posterior (4.5%). The lower extremities are estimated at 36%, 18% for each lower extremity. Again this can be further divided into 9% for the anterior and 9% for the posterior aspect. The groin is estimated at 1%. Burn Surface Area Burn Depth Assessment Clinical examination Pinprick test Laser doppler (note: to assess burn depth, useful for surgery to see what tissues can be removed) Other methods ASSESSMENT OF THE BURN WOUND cont’d Assessing the depth of a burn ▪ The history is important- temperature,time and burning material ▪ Superficial burns have capillary filling ▪ Deep partial-thickness burns do not blanch but have some sensation ▪ Full-thickness burns feel leathery and have no sensation A&E Department Secondary survey Head to toe Clarify history When, Where, How, What type, Clothes, First aid? Past medical history, Tetanus prophylaxis? Nil by mouth Referral to RBU Adult > 15%, Child > 10% Significant areas (Hands, face, genitalia etc) Inhalation injury ANY other concerns Decreased Mortality from Major Thermal Injury has been due to Advances in: Resuscitation Control of Infection Support of the hypermetabolic response to Trauma Early burn wound closure Fluid Resuscitation Formulae 4 ml/kg/% burn balanced salt. Parkland ½ over 8 hrs, ½ over 16 hrs 0.25 ml/kg/% burn/hr Hartmann’s 1st 8 hrs Parkland modified 0.1 ml/kg/% burn/hr 4.5% HAS next 16 hrs (St Andrew’s) 0.5 ml/kg/% burn 4.5% HAS Muir Barclay each in periods of 4-4-4-6-6 hrs 5000 ml/m2/day PLUS Galveston 24 2000 ml/m2 of burn/day. ½ over 8h and ½ over 16h 1500 ml/ m2/day PLUS Galveston 48 3750 ml/m2 burn/day ½ over 8h and ½ over 16h Note: dose calculation – Parkland’s formula 3-4 mL * % BSA * weight Half given in the first 8 hours, the rest in the next 16 hours Start counting since the time of the burn, not the time of admission! (e.g., if the patient had a burn 3 hours ago and is presenting now, you don’t give half the dose over the next 8 hours, but the next 5 hours) In addition, 0.25 mL * % BSA * weight of plasma is given in the last 8 hours to prevent edema by increasing oncotic pressure Special cases: BSA: 80%, don’t use the parkland formula, and simply give 3L of ringer’s lactate over 24 hours and no more than this Weight: don’t count after 70 kg as it’s mostly just fat If the patient presents after 24 hours, special considerations are needed and you should consult a senior Fluid Resuscitation Increased Requirements Delayed or inadequate resuscitation Deep burns Petrol burns Electrical burns Inhalation injury 5.7 ml/kg/% burn Child 5.8 ml/kg/% burn Fluid Resuscitation - Complications Too Little Too Much Hypovolaemia Pulmonary oedema Shock Cerebral oedema Renal failure Gut/Liver oedema Multi-organ failure Compartment syndrome (MOF) Abdomen Limbs Note: results from shifting of fluid to extravascular space with subsequent edema (Dr. Rawand) Nutrition Note: increased protein requirements Supplement Nasogastric / jejunal feeding Formulae Note: early enteral feeding prevents translocation and ileus Note: Causes of death in burns Sepsis Sterilization/washing of the hands before handling Isolation Usually result from contamination of the wounds ARDS Diagnosis of Sepsis Core Temperature >39.5 or < 36.5 Respiratory rate >30/min Hyperglycaemia WBC >15,000 or 105 orgs / gm tissue Positive blood culture Infection Control Topical Antimicrobials Silver – Flamazine (note: Silver sulfadiazine), AgNO3, Acticoat Hypochlorite – (0.025%) Betadine (note: not preferred [irritant, causes acidosis and damages granulation tissue]; don’t use 10%, dilute to 4%, and use for 2 minutes if pseudomonas is suspected [green, foul smell] [Dr. Bashar]) Washing Wounds Bath Shower (106 102 orgs/gm tissue)  Major Thermal Injury Note: tracheostomy can be performed if intubation fails Simplified Referral Criteria 1 Side-note: major burn is >30% BSA >10% TBSA in adults >5% TBSA in children Burns in special areas FTB >5% TBSA Electrical burns (note: needs monitoring as arrhythmia can occur; muscle damage can result in myoglobinuria and haemoglobinuria and these pigments can exacerbate acute renal failure; can pass through bone and cause gangrene??) Chemical burns (note: needs irrigation) Simplified Referral Criteria 2 Burn + inhalation injury Circumferential burn of limbs or chest (note: risk of compartment syndrome, can constrict chest expansion Burns at extremes of age (note: elderly may have comorbidities; children may easily dehydrate) Burns in patients with pre-existing medical disorders Plus associated trauma