Adult Nursing II: The Integumentary System - Disorders and Diseases (Burns)

Anatomy and Physiology of the Skin

The skin is recognized as the largest organ of the human body. It is composed of three distinct layers: the epidermis, the dermis, and the subcutaneous tissue (also known as the hypodermis). The epidermis is the non-vascular outermost layer. The dermis represents the largest portion of the skin, providing essential strength and structure; it contains sebaceous and sweat glands, hair follicles, blood vessels, and nerve endings. The innermost layer, the subcutaneous tissue, contains major vascular networks, fat, nerves, and lymphatics.

Physiologically, the skin serves several critical functions. It regulates body temperature and prevents the loss of essential body fluids while simultaneously preventing the penetration of toxic substances. It protects the body from the harmful effects of the sun and radiation and excretes toxic substances through sweat. Furthermore, it provides mechanical support, acts as a sensory organ for touch, heat, cold, and emotional sensations, and is the site for Vitamin D synthesis.

Integumentary System Disorders

The spectrum of integumentary system disorders includes a wide variety of conditions. These include burns, impetigo, eczema, cellulitis, furunculosis, herpes zoster and herpes simplex, and urticaria. Other conditions involve congenital lesions such as moles and birthmarks, psoriasis, and alopecia. The list also extends to keloids, tumors such as warts, scabies, acne, fungal infections, vitiligo, and paronychia.

Definition and Etiology of Burns

Burns are defined as the results of the effects of thermal injury on the skin and other tissues. Human skin is capable of tolerating temperatures up to a range of $42 - 44^{\circ}C$ ($107 - 111^{\circ}F$). However, once temperatures exceed this range, higher temperatures lead to more severe tissue destruction. Changes resulting from temperatures below $45^{\circ}C$ ($113^{\circ}F$) are generally reversible, but at temperatures greater than $45^{\circ}C$, protein damage exceeds the cell's capacity for repair.

The etiology of burns is categorized by the source of injury. Thermal burns are caused by external heat sources that raise the temperature of the skin and tissues, leading to cell death or black charring; examples include hot metals, scalding liquids, steam, and flames. Radiation burns result from prolonged exposure to ultraviolet rays or other radiation sources like cancer treatments or nuclear leaks. Chemical burns are caused by strong acids, alkalis, detergents, or solvents. Electrical burns occur from alternating or direct currents, such as biting an electrical cable or high-voltage contact. Friction burns involve direct cell damage and heat generated by movement, such as rope burns or falling on a moving treadmill.

Classification and Clinical Manifestations of Burns

Burns are classified by the depth of the injury into four degrees. First-degree (superficial) burns affect only the epidermis, presenting as red, painful, and dry without blisters; mild sunburn is a common example, and long-term damage is rare, usually only involving minor skin color changes. Second-degree (partial thickness) burns involve the epidermis and part of the dermis. The site appears red, blistered, swollen, and painful, often with a wet or shiny appearance and irregular discoloration.

Third-degree (full thickness) burns destroy both the epidermis and the dermis and may extend into the subcutaneous tissue. The area may look white, blackened, charred, dry, or leathery. Notably, these burns are often painless because the nerve endings in the area have been destroyed. Fourth-degree burns extend through both skin layers into underlying muscle and bone, appearing charred or white. Like third-degree burns, they are not painful due to complete nerve destruction.

Pathophysiology of Burn Injury

The pathophysiology of a burn begins as heat causes coagulation necrosis of the skin and subcutaneous tissue. This triggers the release of vasoactive peptides, which leads to altered capillary permeability and a significant loss of fluid. This fluid loss results in severe hypovolemia, which subsequently causes decreased cardiac output and decreased myocardial function. The systemic impact continues with decreased renal blood flow, leading to oliguria or full renal failure. Altered pulmonary resistance may cause pulmonary edema. If the patient survives the initial shock, infection may set in, leading to Systemic Inflammatory Response Syndrome (SIRS) and potentially Multiorgan Dysfunction Syndrome (MODS).

Diagnostic Evaluation and Surface Area Calculation

Diagnosis is generally straightforward, with the patient's history providing clues to the causative agent. A thorough history should include the time of the burn, medicolegal possibilities, and the AMPLE mnemonic: Allergies, Medications, Past medical history, Last meal, and Evans/environment of the injury. Physical examination focuses on the depth of the burn to determine the degree of injury.

The calculation of the Total Body Surface Area (TBSA) of the burn is essential for treatment. In adults, the Wallace’s Rule of Nines is used: the head is $9\%$, each arm is $9\%$, the anterior trunk is $18\%$, the posterior trunk is $18\%$, each leg is $18\%$, and the perineum is $1\%$. In children, the head is $18\%$, the front and back trunks are $18\%$ each, arms are $9\%$ each, and legs are $14\%$ each. For scattered burns, the Palm Method identifies the patient's palm size as approximately $1\%$ of the TBSA.

Admission and Management Criteria

Admission or referral is required for major burns, defined as partial thickness burns over $>25\%$ TBSA in adults, or $>20\%$ in children under 10 and adults over 50. Full thickness burns $>10\%$ TBSA, or any burns involving the face, eyes, ears, and perineum, require admission. Chemical, electrical, and inhalational injuries, as well as burns in patients with underlying debilitating illnesses, also meet admission criteria.

Management begins with the ATLS primary survey protocol. Airway management is critical; airway burns or laryngeal edema may require intubation or tracheostomy. Oxygen inhalation should start at $8 - 12\,L/min$ for patients with dyspnea or major burns. Fluid resuscitation is vital, requiring large-bore cannulas and the Parkland formula to calculate requirements for the first 24 hours: $4\,ml \times \text{weight in kg} \times \% \text{ TBSA}$. The fluid of choice is Ringers Lactate (RL), with $50\%$ administered in the first 8 hours and the remainder over the next 16 hours. Clinicians must monitor for a urine output of $0.5 - 1\,ml/kg/hr$. In the second 24 hours, the total volume is halved, using colloids ($0.5\,ml/kg/\%\text{TBSA}$) and glucose solutions.

Medical Interventions and Patient Care

Necessary investigations include a CBC, coagulation profile (BT, CT, PT), blood grouping, RBS, RFT, Serum Electrolytes, LFT, urine routine, and Chest X-ray. Patients with burns over $20\%$ TBSA require catheterization and a Nasogastric (NG) tube to prevent vomiting and aspiration. Morphine is the drug of choice for pain relief ($10\,mg$ IV slowly for adults; $0.1 - 0.3\,mg/kg$ for children), except in cases of respiratory burns where Pethidine may be an alternative.

Antibiotics such as Ceftazidime, Amikacin, or Metronidazole are typically not used until 48 hours post-burn. To prevent acute stress ulcers, Magnesium Ranitidine ($50\,mg$ every 8 hours) is administered. Tetanus prophylaxis ($0.5\,cc$ IM stat) is required. Wound care involves sterile precautions, cleaning with dilute Savlon or Normal Saline, debridement of blisters, and the application of Silver Sulphadiazine or Soframycin ointment covered by Vaseline gauze. From the third day, nutrition is prioritized with oral fluids, fortified milk, and protein and vitamin supplements. Supportive therapy includes physiotherapy for joints and rehabilitation.

Complications

Complications are divided into early and late stages. Early complications include burn shock, renal failure, smoke inhalation syndrome, and septicemia. Late complications often involve physical changes such as hypertrophic scars, keloids, and contractures.