Burns



Burns


Shreyajit R. Kumar

Anup Pamnani

Michael Tjeuw





A. Medical Disease and Differential Diagnosis



  • How do you classify the burn injury?


  • How do you express the extent of the burn injury?


  • Should the “rule of nines” be used in children?


  • What is the definition and etiologies of a major burn according to the American Burn Association?


  • What functions does the skin perform?


  • What pathophysiologic changes accompany major thermal injury?


  • Name some of the known mediators released with thermal injury. What are the responses to those mediators?


  • What is the prognosis for this patient? What major factors affect his prognosis?


  • What are the most common causes of death?


  • Does this patient have a smoke inhalation burn? How do you make the diagnosis?


  • What is carbon monoxide poisoning? How do you diagnose and treat carbon monoxide poisoning?


  • What resuscitative measure would you institute immediately in this patient with 40% burns?


  • What fluid formula would you use?


  • What cardiovascular changes typify the burn injury?


  • What hematologic changes occur in burn injury?


  • What changes occur in liver function? What are the anesthetic implications of such changes?


  • What are Curling ulcers? How can they be prevented?


  • What complications are associated with electrical burns?


B. Preoperative Evaluation and Preparation



  • What preoperative preparations would you order? What are particular concerns in this patient?


  • What are the various operative and management options available for severely burned patients?



  • What are the advantages and disadvantages of early tangential excision splitthickness skin grafting (TE/STSG)?


  • What is this patient’s mean arterial blood pressure? How do you calculate it?


  • Are you concerned about this patient’s blood pressure? What treatment would you institute?


  • This patient was ventilated with respirator settings of tidal volume, 800 mL; respiratory rate, 20 breaths per minute; FIO2, 60%; and positive end-expiratory pressure, 10 cm H2O. Arterial blood gas analyses showed the following: pH, 7.24; PO2, 56 mm Hg; PCO2, 60 mm Hg; and O2 saturation, 80%. How would you interpret these arterial blood gas analysis results? What are the possible causes of high PCO2 and low PO2?


  • How do you calculate oxygen content and oxygen delivery? What factors govern the oxygen delivery to the tissues?


  • What are the symptoms and signs of alcohol withdrawal? Are you concerned that this patient could develop delirium tremens?


  • How would you prevent the adverse effects of alcohol withdrawal?


C. Intraoperative Management



  • What monitors would you use in the operating room?


  • What information can be obtained from an arterial line and a pulmonary artery catheter? How are these calculations performed?


  • If the patient had not been intubated, how would you proceed with the anesthetic induction?


  • Why is awake intubation considered the safest?


  • What anesthetic agents would you use? Discuss inhalation versus intravenous agents.


  • Why are you concerned about the patient’s body temperature? What is normothermia for a burned patient?


  • How is temperature best maintained?


  • What derangements occur with hypothermia?


  • What muscle relaxant would you use?


  • Why is succinylcholine contraindicated in burned patients? For how long should it be avoided?


  • What other adverse effects are associated with succinylcholine?


  • How are the doses of nondepolarizing muscle relaxants affected by burn injury?


  • How are the muscle relaxants such as succinylcholine, atracurium, cisatracurium, vecuronium, pancuronium, rocuronium, and curare metabolized and eliminated? Which of them has significant histamine release?


  • What is the difference between metabolism and elimination of drugs?


D. Postoperative Management



  • How would you monitor this patient during transport?


  • What is meant by diffusion hypoxia? How do you prevent it?


  • Why do patients often shiver in the recovery room on emergence from anesthesia?


  • Discuss the causes of oliguria in the recovery room.


A. Medical Disease and Differential Diagnosis


A.1. How do you classify the burn injury?

Burns classification is based on both depth and degree of tissue injury. First-degree burns are superficial and confined to epidermal injury. Second-degree burns are partial-thickness, involving the epidermis and dermis. Second-degree burns are subdivided into superficial
and deep dermal burns. Third-degree burns are full-thickness and characterized by irreversible destruction of all dermal and epidermal elements. Fourth-degree burns involve injury to underlying tissue structures—muscle, fascia, tendon, and bone (Table 56.1).








TABLE 56.1 Classification of Burn Depth













































CLASSIFICATION


BURN DEPTH


OUTCOME


Superficial



First degree


Confined to epidermis


Heals spontaneously


Partial thickness



Second degree




Superficial dermal burn


Epidermis and upper dermis


Heals spontaneously




Deep dermal burn


Epidermis and deep dermis


Requires excision and grafting for rapid return of function


Full thickness



Third degree


Destruction of epidermis and dermis


Wound excision and grafting required


Some limitation of function and scar formation



Fourth degree


Muscle, fascia, bone


Complete excision required, limited function


From MacLennan N, Heimbach DM, Cullen BF. Anesthesia for major thermal injury. Anesthesiology. 1998;89:749-770, with permission.




MacLennan N, Heimbach DM, Cullen BF. Anesthesia for major thermal injury. Anesthesiology. 1998;89:749-770.

Townsend CM, Beauchamp RD, Evers BM, et al, eds. Sabiston Textbook of Surgery. 19th ed. Philadelphia, PA: Elsevier Saunders; 2012:521-547.


A.2. How do you express the extent of the burn injury?

Extent of burn injury is expressed as a total body surface area (TBSA) percentage. Burn size is estimated by the “rule of nines” (Fig. 56.1). In adults, each upper extremity and the head and neck are 9% of TBSA. The lower extremities and anterior and posterior trunk are 18% each, and the perineum is approximately 1% of the TBSA. The burn proportions are additive, yielding a TBSA burn.



MacLennan N, Heimbach DM, Cullen BF. Anesthesia for major thermal injury. Anesthesiology. 1998;89:749-770.

Townsend CM, Beauchamp RD, Evers BM, et al, eds. Sabiston Textbook of Surgery. 19th ed. Philadelphia, PA: Elsevier Saunders; 2012:521-547.


A.3. Should the “rule of nines” be used in children?

The “rule of nines” will not estimate TBSA burns in children because the head and neck comprise a relatively larger portion of the body surface area and a smaller surface area in the lower extremities. The Lund and Browder chart represents a precise method, accounting for the changing proportions of the TBSA from infancy to adulthood (Fig. 56.2).



MacLennan N, Heimbach DM, Cullen BF. Anesthesia for major thermal injury. Anesthesiology. 1998;89:749-770.

Townsend CM, Beauchamp RD, Evers BM, et al, eds. Sabiston Textbook of Surgery. 19th ed. Philadelphia, PA: Elsevier Saunders; 2012:521-547.


A.4. What is the definition and etiologies of a major burn according to the American Burn Association?

The American Burn Association defines a Brunicardi burn as follows:



  • Full-thickness burns more than 10% TBSA


  • Partial-thickness burns more than 25% in adults or 20% at extremes of age


  • Burns involving face, hands, feet, or perineum







FIGURE 56.1 The rule of nines for determining the percentage of body surface area burned in adults. (Adapted from MacLennan N, Heimbach DM, Cullen BF. Anesthesia for major thermal injury. Anesthesiology. 1998;89:749-770.)

The American Burn Association accounts for the following etiologies of burn injury:



  • Flame—from superheated oxidized air


  • Scaled—from hot liquid


  • Contact—from hot or cold solid materials


  • Chemicals—from noxious chemicals


  • Electricity—conduction of current through tissues



Townsend CM, Beauchamp RD, Evers BM, et al, eds. Sabiston Textbook of Surgery. 19th ed. Philadelphia, PA: Elsevier Saunders; 2012:521-547.


A.5. What functions does the skin perform?

The skin is the largest organ of the body with a surface area ranging from 1.5 to 2.0 m2 in the adult. It is the primary immune barrier, protecting against microorganism invasion. The skin provides thermal regulation, fluid and electrolytes homeostasis, vitamin D metabolism, and sensation (touch, temperature, pain).



Herndon DN, ed. Total Burn Care. 4th ed. Philadelphia, PA: Saunders Elsevier; 2012:125-126, 209.


A.6. What pathophysiologic changes accompany major thermal injury?

The pathophysiologic alterations that accompany major thermal injury are complex. Destruction of the skin—the largest organ of the body—has a profound systemic impact. Thermal regulation, fluid and electrolyte homeostasis, and protection against bacterial infection are all lost. Inflammatory mediators released from burn injury result in a leaky capillary syndrome; fluid and albumin are sequestered from the intravascular compartment into the burn wound, causing hemoconcentration and hypoalbuminemia. Increased secretion of antidiuretic hormone may cause oliguria or anuria.







FIGURE 56.2 Diagram and table for determining the percentage of body surface area burned in children. (Adapted from MacLennan N, Heimbach DM, Cullen BF. Anesthesia for major thermal injury. Anesthesiology. 1998;89:749-770.)

The metabolic rate is markedly increased after the burn injury. Depending on the size of the burn, the increase in metabolic rate can be doubled or tripled with a proportionate increase in oxygen consumption and carbon dioxide production. This hypermetabolic state will continue for weeks or months until full skin coverage is achieved and the tissue repair processes are complete.

Cardiac output (CO) is often decreased in patients with major burns. This decrease is partially due to a rapid reduction in circulating blood volume as well as an upregulation of circulating myocardial-depressant factor.

Changes in vascular integrity occur in other areas remote from the injury site. The entire vascular compartment becomes permeable to circulating macromolecules, manifesting as edema. Severe pulmonary edema can be life-threatening. Airway edema is the impetus for early intubation.

Pulmonary function is significantly altered. A reduction occurs in all of functional residual capacity, lung capacity, and chest wall compliance. Increases occur of the alveolar-arterial oxygen gradient (PAO2-PaO2) and minute ventilation (as high as 40 L per minute; normal, 6 L per minute).



Brunicardi FC, Andersen DK, Billiar TR, et al, eds. Schwartz’s Principles of Surgery. 10th ed. New York: McGraw-Hill; 2015:227-326.

Herndon DN, ed. Total Burn Care. 4th ed. Philadelphia, PA: Saunders Elsevier; 2012:103-115.

MacLennan N, Heimbach DM, Cullen BF. Anesthesia for major thermal injury. Anesthesiology. 1998;89:749-770.


A.7. Name some of the known mediators released with thermal injury. What are the responses to those mediators?

After a thermal injury, mediators released from the burn wound contribute to local inflammation and edema. Local mediators include histamine, prostaglandins, thromboxane, bradykinin, nitric oxide, serotonin, catecholamine, and platelet aggregation factor.







FIGURE 56.3 Mediators released with thermal injury and the response to their release. TNF, tumor necrosis factor. (From MacLennan N, Heimbach DM, Cullen BF. Anesthesia for major thermal injury. Anesthesiology. 1998;89: 749-770, with permission.)

In minor burns, the inflammatory process is limited to the wound itself. In major burns, local injury triggers the release of circulating (systemic) mediators, resulting in a systemic response. This response is characterized by hypermetabolism, immune suppression, and the systemic inflammatory response syndrome (protein catabolism, sepsis, multiple organ failures).

The systemic mediators are cytokines (interleukins), endotoxin, and nitric oxide (Fig. 56.3).



Brunicardi FC, Andersen DK, Billiar TR, et al, eds. Schwartz’s Principles of Surgery. 10th ed. New York: McGraw-Hill; 2015:227-326.

Herndon DN, ed. Total Burn Care. 4th ed. Philadelphia, PA: Saunders Elsevier; 2012:103-115.

MacLennan N, Heimbach DM, Cullen BF. Anesthesia for major thermal injury. Anesthesiology. 1998;89:749-770.


A.8. What is the prognosis for this patient? What major factors affect his prognosis?

The prognosis for this patient is very poor. Statistical survival based on TBSA alone would predict a less than 50% chance of survival. Other factors that affect his prognosis are age, size and depth of burn, associated pulmonary injury, and preexisting medical disease. In this patient with a history of angioplasty for coronary artery disease, hypertension, heavy smoking, and obesity, the risk of myocardial infarction is greatly increased.


A.9. What are the most common causes of death?

The major early cause of death is asphyxia. The most common cause of long-term mortality is septic complications. Hypovolemic shock is no longer common in the United States due to a better understanding of early goal-directed resuscitation.


A.10. Does this patient have a smoke inhalation burn? How do you make the diagnosis?

The patient probably sustained a smoke inhalation burn. Smoke inhalation should be highly suspected in patients who were burned in an enclosed space, received burns of the face, were burned while under the influence of alcohol or drugs, or lost consciousness at the time of the accident.

A patient with smoke inhalation often exhibits no physical signs or symptoms during the first 24 hours after the burn—the “lucid period.” The early symptoms and signs of respiratory tract
injury include burned nasal mucosa/lips/mouth, singed nasal hair, hoarseness, wheezing, and soot in the sputum. The posterior pharynx may appear red, and the larynx may appear edematous. Radiographic findings are usually negative immediately after injury. Laboratory tests include blood gas analysis, carboxyhemoglobin concentration, xenon scans, and fiberoptic bronchoscopy.



Brunicardi FC, Andersen DK, Billiar TR, et al, eds. Schwartz’s Principles of Surgery. 10th ed. New York: McGraw-Hill; 2015:227-326.

Herndon DN, ed. Total Burn Care. 4th ed. Philadelphia, PA: Saunders Elsevier; 2012:229-239.

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Mar 18, 2021 | Posted by in ANESTHESIA | Comments Off on Burns
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