Week 11: Burn Injuries PDF

Week 11: Burn Injuries Burns General term describes cutaneous injury - Thermal Friction, cold, heat - Nonthermal Radiation, chemical, electrical Each cause requires different approach in diagnosis and treatment Multisystem injuries with...

Week 11: Burn Injuries Burns General term describes cutaneous injury - Thermal Friction, cold, heat - Nonthermal Radiation, chemical, electrical Each cause requires different approach in diagnosis and treatment Multisystem injuries with interactions of shock, inflammation, and immunocompromised state Physiologic response dependent on extent of burn surface involvement and depth of tissue destruction Classification of Burn Wound Depth Based on physical appearance and symptoms associated with affected skin Definitive diagnosis determined by histologic depth of tissue necrosis Laser doppler imaging determine burn wound depth - Non-invasive mechanical extension of clinical physical exam - Assesses burn injuries and guides decision to perform surgical excision or grafting Burn Wound Depths First-degree (superficial) Second-degree (partial thickness – superficial and deep) - Two categories of burn depth with markedly different characteristics - Both are partial-thickness injuries, but they evoke vastly different responses Third-degree (full thickness) Fourth-degree (extends beyond epidermis, dermis, subcutaneous tissue) First Degree Burn Superficial - Involves only epidermis - Without injury to underlying dermal or subcutaneous tissue - Area is dry (no blisters) Initially there is local pain and erythema What is an example of a If extensive first degree burn? - May cause systemic responses - Chills, headache, localized edema, nausea, vomiting First-degree burns heal in 3 to 5 days without scarring Second Degree Burns Superficial partial-thickness injury  Thin-walled, fluid-filled blisters develop within few minutes after injury Severe pain! - Tactile and pain sensors remain intact throughout healing Each wound care procedure causes substantial pain!! - Wounds heal in 3 to 4 weeks Scar formation is unusual Deep partial-thickness injury Involves entire dermis, sparing skin appendages such as hair follicles and sweat glands Often looks waxy white and is surrounded by margins of superficial partial-thickness injury Skin may peel off in sheets Takes weeks to heal Wounds that heal slowly produce more scar tissue and continue to be potential source of infection until closed Commonly results in hypertrophic scarring with poor functional and cosmetic results Hypertrophic Scarring Third Degree Burns Full-thickness injury - Entire epidermis, dermis, and often underlying subcutaneous tissue destroyed - Muscle or bone may be involved - Burn color is white, cherry red, or black - Blisters are rare - Wound dry and leathery  As marked edema develops, distal circulation may be compromised in areas of circumferential burns Escharotomy is performed to release underlying pressure Injury is painless because nerve endings have been destroyed Fourth Degree Burns Extends beyond epidermis, dermis, subcutaneous tissue into muscle, bone, or tendon Require extensive surgical repair with flaps or even amputation Burns are painless because all of vasculature and nerves of dermis are destroyed Use Your Clinical Judgement A person arrives at the emergency department with a burn injury. The burn area is covered with thin-walled, fluid-filled blisters and is very painful. The nurse suspects this is a: first-degree injury superficial partial-thickness injury deep partial-thickness injury full-thickness injury How do we estimate the Rule of Nines extent of burn injury?  Lund and Browder Chart Answer: Total Body Surface Area  Body surface burn extent described by percentage of total body surface area injured Burns exceeding 20% in most adults - Considered major burn injuries - Associated with massive evaporative water losses and fluid and electrolyte imbalances Generalized edema Circulatory hypovolemia Burn Injury Phases 1. Ebb phase Occurs during immediate postburn period; continues for 72 to 96 hours Hypometabolic state - Reduced oxygen consumption, depleted intravascular volume, low cardiac output, poor tissue perfusion, cellular shock 2. Flow (catabolic) phase After resolution of shock and restoration of circulating volume Hypermetabolic state - Increased oxygen consumption, BP, insulin resistance, breakdown of glycogen, proteins, lipids - Elevation of catecholamines, glucocorticoids, glucagon Persists until wound closure Immediate (Acute) Consequences of Major Burn Injury Life-threatening hypovolemic shock within few hours of burn injury - Massive fluid losses from circulating blood volume - Caused by increase in capillary permeability persisting for approx. 24 hours after burn injury Two components - Cardiovascular - Cellular Cardiovascular Immediate response leads to hypometabolic Response to Burn response Injury - Low cardiac output Increased levels of nitric oxide after burn injury - Can severely depress cardiac function  But then…stress mediators i.e., catecholamines, glucocorticoids, and cytokines released - Heart goes into hyperdynamic overdrive, increasing circulation and blood flow to increase oxygen and nutrient delivery! Cellular response to burn injury Apoptosis is main factor Other cellular responses to burn injury are - Metabolic - Immunologic Metabolic Response “Sick cell syndrome” Altered cell membrane permeability and loss of normal electrolyte homeostasis - May be responsible for origin of burn shock Sodium-potassium pump impairment - Intracellular sodium and water increase - Intracellular potassium concentration decreases Decrease in resting membrane potential, decrease in amplitude of action potential, prolongation of repolarization and depolarization times Loss of intracellular magnesium and phosphate Other Metabolic Sympathetic nervous system Response Catecholamines elevated Cortisol, glucagon, insulin levels elevated Increase in gluconeogenesis, lipolysis, proteolysis Changes in lipid metabolism Elevation in level of plasma free fatty acids Glucose and lactate altered Although tissue hypoxia produces lactic acidosis, its persistence in presence of adequate tissue perfusion suggests increased rate of glycogenolysis Hepatic response Hypercoagulable state develops - Elevated plasma fibrinogen concentration - Shortened prothrombin time (PT) - Activated partial thromboplastin time (PTT) Hypermetabolic State Related to increase and resetting of thermal regulatory set point Increased resting energy expenditure, elevated core temperature (38.5°C], total body protein loss, muscle wasting, increased synthesis of acute-phase proteins - Results in organ catabolism associated with  organ dysfunction and death Cytokines, oxygen free radicals, chemotactic substances, eicosanoids Contribute to systemic inflammatory response and hypermetabolic state Inflammatory response Vasodilation, increased capillary permeability, edema occur to facilitate healing of local area - Distribution of peripheral circulation transports heat and glucose preferentially to wound - Energy cost of these reparative and transport processes reflected in increased metabolism and hyperdynamic circulation Alterations in Body Metabolism: A Summary Immunologic Response Immediate, prolonged, severe Release of cytokines, oxygen free radicals, chemotactic factors, eicosanoids - Leads to systemic inflammatory response! Macrophages, platelets, neutrophils, vascular endothelial cells release prostaglandins and leukotrienes - Chemical mediators cause peripheral vasodilation, pulmonary vasoconstriction, increased capillary permeability, and local tissue ischemia in burn wound  Release of histamine and serotonin by C3a and C5a - Alter capillary permeability Changes in integrity of intestinal wall - Facilitates bacterial translocation and endotoxemia Circulating endotoxin can result in multiple organ dysfunction and death Opsonins render bacteria susceptible to phagocytosis - But…burn injury triggers consumptive opsoninopathy Burn serum contains an inhibitor of C3 conversion that leads to decreased opsonization and polymorphonuclear (PMN) dysfunction Immunosuppression with increased susceptibility to potentially fatal systemic burn wound sepsis Cellular and Immunologic Alterations Evaporative Water Loss Daily evaporative water loss is approximately 20 times normal in early phase of burn injury Ability of skin to regulate evaporative water loss disrupted - Insensible water loss through burned skin increases Insensible water loss via lungs increases by hypermetabolism and hyperventilation - Especially in intubated client  Total evaporative losses exceed many liters per day in an adult with large burn wounds - Replacement of losses necessary to prevent volume deficit! Severe Burn Injury Complex Response: The Big Picture Burn Injury : Treatment Essential elements of major burn injury survival - Meticulous wound management - Adequate fluids and nutrition - Early surgical excision and grafting Management of burn pain is key to recovery Fluid Resuscitation in Primary goal of fluid resuscitation Burn Injuries - Maintain adequate tissue and organ perfusion Severe burns result in hypovolemic shock and loss of body fluid through third spacing, exudation, evaporation  Client in hypovolemic shock will decrease or stop urine output - Compensatory mechanism to preserve circulatory volume Resuscitation done using different infusion protocols - Infusion of IV fluid at rate faster than loss of circulatory vascular volume for period of approx. 24 hours from time of burn injury - May require up to 30 L in a major burn Adult receiving sufficient IV fluids will excrete 30 to 50 mL/h; children will produce 0.5 to 1 mL/kg/h Most reliable criterion for adequate fluid resuscitation of burn shock is urine output - If client does not have adequate urine output, often indicates inadequate fluid resuscitation Direction of Fluid and Electrolyte Shifts Endpoint of burn shock defined as client able to maintain adequate urine output for 2 hours with IV fluid administration rate equal to calculated maintenance rate As burn shock ends - Fluid remains in circulating volume and is reflected as increase in urine output Capillary integrity is restored about 24 hours after burn injury Endpoint of burn shock - “Capillary seal” Fluid Resuscitation: Parkland Formula Purpose: - Crucial for improving outcomes in major burn injuries by rapidly restoring circulatory volume. Formula: - 4 mL of Lactated Ringer’s solution per kg of body weight per % TBSA burned.  Calculation: - 4 mL x (body weight in kg) x (% TBSA burned) Administration Schedule - First 8 Hours: Administer half of the total calculated fluid volume. - Next 16 Hours: Administer the remaining half. Example: A 70 kg person with 50% TBSA burns - 4 mL (70kg)(50%)(100) = 14.0 L = 14,000 mL - First 8 hr administer 7.0 L = 7,000 mL - Next 16 hours administer 7.0 L = 7,000 mL Why Lactated Ringer’s Solution? - Closely approximates extracellular fluid Systemic Response to Burn Injury Burns can result in swelling and edema Edema inevitable with fluid resuscitation - But…failure to administer fluid resuscitation results in irreversible hypovolemic shock and death! Edema develops in unburned and burned areas Edema often leads to - Mechanical airway obstruction requiring tracheal intubation - Increased severity of interstitial pulmonary edema Use Your Clinical Judgement A nurse is assigned to care for a client with a 40% deep partial-thickness injury. Which parameter will the nurse closely monitor to best assess adequate fluid resuscitation? Hematocrit level Heart rate Urine output Blood pressure Pharmacotherapy of Burn Injuries 1. Superficial/ First Degree Burns Non-opioid analgesics: ACETAMINOPHEN  Indications Tx of fever and mild to moderate pain Mechanism of Action Inhibits synthesis of prostaglandins in CNS, direct action at level of hypothalamus; causes dilation of peripheral blood vessels, enabling sweating and dissipation of heat Desired effects Reduces fever and pain Adverse Effects (very rare at therapeutic dose) But acute toxicity includes N/V, abdominal discomfort Can also cause liver toxicity and liver damage NSAIDS: IBUPROFEN Indications relieve mild to moderate pain, fever, and inflammation Mechanism of Action inhibition of prostaglandin synthesis Desired effects reduction of pain, temperature, and inflammation Adverse Effects nausea, heartburn, epigastric pain, dizziness, GI ulceration with occult or gross bleeding 2. Partial Thickness/ Second Degree Burns Opioids: MORPHINE Indications acute and severe chronic pain, acute MI pain, cancer pain  Mechanism of Action binds with mu and kappa receptors in brain and dorsal horn of spinal cord mimics endogenous opioids such as endorphins and enkephalins (also stimulate opioid receptors) Desired effects alters perception and emotional response to pain produces profound analgesic and euphoric effects Adverse Effects - dysphoria (restlessness, depression, anxiety) - Hallucinations - nausea, constipation - orthostatic hypotension, dizziness - Pruritus - respiratory depression, cardiac arrest 3. Full Thickness/ Third Degree Burns Barbiturate and barbiturate-like agents: DIAZEPAM Indications sedation, anxiety, skeletal muscle relaxation Mechanism of Action binds to GABA (inhibitory) receptors - when receptor is stimulated, chloride ions move into cell, thus suppressing ability of neurons to fire Desired effects major effect of enhancing GABA activity is CNS depression and sedation Adverse Effects hypotension, respiratory depression, dizziness, H/A, constipation Burn Injuries in Children Common result of - Inadequate supervision, curiosity, inability to escape burning agent, intentional abuse Scald injuries - Most common in young children - Hot water, grease, other hot liquids Flame injuries - Most common in older children - Older children: gasoline  Other burns: - Electrical burns: high or low voltage current - Chemical burns: swallowing caustic agents Child abuse - Pattern burns, forced emersion burns, splash or spill burns inappropriate for age, cigarette burns Burn Injuries in Young Children Child’s skin is thinner and more susceptible to injury than an adult’s Extent of injury is determined by - Temperature of burning agent - Duration of exposure Very young children may be unable to escape heat source - Depth of injury likely to be greater Kitchen tends to be common site for burn injury - Pulling over dishes or appliances containing hot liquids Tap water burns compared to other scald burns, likely to be more severe and cover greater surface area of body Child Abuse Can occur at any But young children are particularly vulnerable age to serious injury Abuse is Historical inconsistencies and physical suggested with examination Incompatible burn and developmental level Bilateral or mirror image burns Localized burns to genitals, buttocks, and perineum (especially at toilet-training stage) Evidence of excessive delay in seeking treatment Presence of other forms of injury Burns Suggesting Nonaccidental Trauma Patterned burns Forced immersion burn patterns with sharp stocking or glove demarcation and sparing of flexed protected areas Splash/spill burn patterns not consistent with history or developmental level Contact burns with well-defined margins of the object Burn Pattern Typically Seen After Forced immersion in hot water How to Assess Severity of Injury in Children Total body surface area - Rule of Nines: Inaccurate in children! Arms and trunk same proportions as adult Head and neck: 18% Each lower extremity: 14% Modified Rule of Nines - Modification deducts 1% from head and adds 0.5% to each leg for each year of life after 2 years of age Other Important Factors in Assessing Severity of Injury 1. Age Children younger than 2 years old have significantly higher risk for associated morbidity and mortality Have not achieved maturity of immune system and  are at increased risk for infection and sepsis Very young children intolerant of rapid fluid shifts; immature renal function negatively affects ability to retain sodium and water 2. Areas of body burned 3. Depth of Injury Infant skin is extremely fragile and more likely to sustain a deeper burn Nature of infant skin makes estimation of burn depth difficult in very young children, especially following scald injuries 4. Secondary Bleeding and fractures injuries and manifestations Major Burn Trauma in Children Integument Cellular destruction and damage Significant edema can result not only in area of injury but also in unburned areas  Loss of substantial areas of skin - Direct and evaporative fluid losses are immediately seen Cardiovascular System Significant reduction in cardiac output occurs immediately after injury Systemic vascular resistance initially increased Younger children more susceptible to increased intraabdominal pressure Pulmonary System Manifestations Inhalation injury, pulmonary edema, respiratory failure, aspiration, pneumonia Small degree of edema Results in increased work of breathing in children Fatigue, related to increased work of breathing Results in more rapid desaturation than in adults Soft cartilage of pediatric airway Prone to collapse in presence of partial obstruction Increased pliability of rib cage causes Constriction of chest and impairment of respiratory excursion in very young children Adult airway VS Pediatric airway Renal System Children younger than 2 years unable to concentrate urine because of immaturity of renal system - At increased risk for dehydration Myoglobin - Pink to red pigment in urine (breakdown of  muscle tissue and hemolysis of RBCs) - Common after extensive electrical injuries and destroyed muscle from deep thermal injury - Release of myoglobin may occlude kidney tubules and result in renal failure Gastrointestinal System Mucosal atrophy occurs, digestive absorption changes, and intestinal permeability increases Depending on burn size, atrophy of gastrointestinal tract mucosa can occur - Leads to increased bacterial translocation and sepsis Paralytic ileus often occurs after major burn injury Immune Function Young children at increased risk for microbial invasion caused by immature immune system and limited antibody production Cytokines increase inflammation by enhancing catabolism and hypermetabolism - Proinflammatory function of cytokines enhances protection from sepsis - Anti-inflammatory function supports anabolism (tissue repair) Infection - Local and systemic infections become primary complication during healing - Children are immunosuppressed for many weeks after injury Meticulous wound care decreases frequency and duration of septic episodes caused by wound flora Burn Shock in Children Hypovolemia and extracellular sodium depleted Urine output - Most accurate parameter of adequacy of fluid resuscitation Urine output of 1 mL/kg/hour in children weighing less than 30 kg Hypotension is late sign in children! Burn Injury in Children: Fluid Resuscitation Children require fluid resuscitation for smaller burns than adults Child’s relatively greater ratio of body surface area to weight results in - Increased evaporative water losses - Proportionately more fluid during resuscitation Fluid resuscitation generally required for children after thermal injuries in excess of 10% to 15% of their total body surface area Burn Injury in Children: Nutritional support Complex metabolic alterations are observed after burn injury - Glycogen stores for meeting increased energy demands of burn is limited in children - Initiation of protein and lipid catabolism for glycogenesis is accelerated - Prolonged metabolic dysfunction may lead to loss of lean body mass and increased morbidity Nutritional support - Children with burns in excess of 20% of total body surface area often require supplementation with tube feeding - Anabolic steroid agents along with nutritional support administered to children Improve muscle protein metabolism through enhanced protein synthesis efficiency - Metabolism of vitamins and trace minerals increased Micronutrient supplementation necessary - Up to 2.5–4 g protein/kg/day needed for children Burn Injury in Children: Surgical Interventions Escharotomy is a procedure that relieves pressure, restores circulation, and improves muscular and respiratory effort Release of pressure is required by a fasciotomy to restore blood flow and preserve nerve function Burn Injury in Children: Wound Management  Deep dermal or full-thickness burn injuries are surgically excised as soon as child is hemodynamically stable Split-thickness sheet grafts are used If burn area is large, mesh autografts used Meshing technique used to expand available skin and increase size of graft Heals by migration of epithelium from meshed edges Burn Injury in Children: Comfort Management Significant challenge in pediatric population Procedural pain and background pain are present without activity Pain perception affected by degree of emotional overlay or affective experience Measurement of pain particularly challenging in young infants, who lack language skills to express pain - Variety of tools available, from physiologic monitors to behavioral analyses and analog scales Burn Injury in Children: Recovery & Rehabilitation Recovery Very young children present unique challenges - Small body size difficult to fit with pressure garments and splints - Growth is rapid - Cooperation limited Children require specialized management to ensure optimal functional and cosmetic results - Scar and contracture management necessary for prolonged periods because of changes in body composition as child grows and matures Rehabilitation Major focus once wound is covered Continues until all reconstructive procedures have been completed - May extend over many years in pediatric population Physical therapy Occupational therapy Psychosocial support Transition from hospital to community: Especially reentry into school