Anesthesiology

Burns

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What the Anesthesiologist Should Know before the Operative Procedure

Preoperative evaluation of a burned patient involves a thorough history and physical examination with particular attention placed on the following aspects of the history and physical:

In history, the mechanism of the burn and time out from the burn can be of vital importance. The mechanism of the burn (e.g., scald, house fire, electrical, vehicular, chemical) will often direct the focus and attention to certain systems (e.g., electrical may involve cardiac injury from the current passing through the myocardium). Likewise the time out from the burn will guide the clinician as to whether the patient is likely to suffer from global organ dysfunction, in the immediate acute period of the first 3 to 5 days, or conversely have a hypermetabolic physiology in the weeks following the burn injury.

The size of the burn combined with time out from the burn will help direct fluid management. Physical examination in the acutely burned patient must pay particular attention to the airway (especially if the patient is the victim of a fire in an enclosed space where super-heated air can cause thermal injury to the pharynx, glottis, trachea, and primary and secondary bronchi) and inhalation of toxic chemicals can injure the distal airways. Other physical examination findings include restrictions to mouth opening, neck mobility, and even chest excursions caused by burn scar formation. These may make securing an airway and/or ventilating a patient quite challenging.

History

Minimal focused history from a burn patient includes mechanism of burn, size of burn, time out from burn, resuscitation required, and prior intubation and airway manipulation history. Note airway management on burn patients can be very dynamic. The patient who was an easy intubation in the emergency ward may be very different after volume resuscitation and burn scarring/healing.

Mechanism of burn

Was the cause of the burn a scald, flame, enclosed space/inhalational, chemical, or electrical?

Scald burns may be deceptive in the body's responses. Even though the scald is often localized (e.g., lower extremities), the body's responses, including volume loss, organ dysfunction, heat loss, and vulnerability to infection, are systemic and generalized. If the scald patient has been volume resuscitated, he may be globally edematous including laryngeal and pulmonary edema. Pulse oximetry may be difficult to obtain on swollen digits with poor perfusion.

Flame burns may appear focal but have generalized and systemic responses including volume loss and organ dysfunction involving areas far from the actual site of burn injury.

Enclosed space/inhalational burn injury can present with a very sick patient much more involved than the external appearance may indicate. Enclosed spaces present not only thermal burn injuries, but also inhalational and chemical injuries. Super-heated air in a house fire can reach 1000 degrees F (538 degrees C) and not only burn external skin, but also the initial parts of the tracheobronchial tree (up to the secondary bronchi). The body's heat exchange systems are quite efficient and it is unlikely that the tertiary bronchi and alveoli will get thermal injuries. They may, however, suffer from chemical injuries including the inhalation of products of combustion and incomplete combustion of hydrocarbons and other synthetics consumed in a house fire. These may cause a chemical burn of the distal airways with sloth of the entire mucosa of the tracheobronchial tree and destruction of the ciliated epithelium, goblet cells, etc., leaving the lungs vulnerable to infection.

Carbon monoxide (CO) poisoning from an enclosed space fire is possible due to the incomplete combustion of hydrocarbons generating CO. CO acts both on hemoglobin, shifting the hemoglobin dissociation curve to the left and occupying oxygen binding sites, as well as on oxygen transport and cellular respiration in the mitochondria. CO poisoning should be treated with the highest FIO2 available (typically 100% oxygen from a nonrebreather mask or via endotracheal tube). Some advocate hyperbaric oxygen therapy (HBOT) for severe CO poisoning or in the case of pregnant patients exposed to CO.

Chemical burns should be evaluated for oral exposure/ingestion and possible need to secure the airway. Some chemicals—notably vesicants—may remain on clothes and skin and pose a danger to health care staff. Inhalation of SO2 and NO2 will combine with exhaled water and form nitric and sulfuric acid chemical burns of distal airways.

Electrical burns often present with a small entry and exit point but may have massive internal injury. Myonecrosis and rhabdomyolysis are common with resulting potential for renal injury. A thorough cardiac evaluation needs to be performed if the history suggests that the electrical current has passed through the myocardium. Always look for the entry and exit wounds!

The size of the burn is predictive of secondary responses such as degree of organ dysfunction and leakiness of capillaries. Burn size may be calculated by the Rule of 9s. Typically, systemic responses to flame/scald burns are not of significance for burns smaller than about 20%. Remember that you will find it does not apply to toddlers and that the head may account for 20% of the body surface area.

The time from the burn injury is an important predictor of the patient's physiology—whether depressed function in the acute phase of burn injury (typically the first 5 days) or elevated organ function in the hypermetabolic period that follows the acute phase.

Resuscitation required prior to arrival in the operating room suite is an important predictor of volume status and potential edema including laryngeal and pulmonary. One of the most important advances in burn care has been relatively aggressive volume resuscitation. Two formulas are frequently used to determine volume requirements during the first days of the acute phase (prior to the patient's own spontaneous diuresis) are the Parkland and Brooke. Remember that these formulas will underestimate fluid requirements of children who weigh10 kg or less.

Prior difficulties with airway management should be elicited, but it is important to stress the dynamic nature of the airway of the burn patient. An airway that was patent and easy to manipulate on day one of burn injury may be next to impossible on the following day. Especially with enclosed spaces/inhalational injury, it may be prudent to leave a patient intubated during the acute phase as the airway may deteriorate due to responses from the thermal injury and/or volume resuscitation. We strongly suggest not extubating or attempting endotracheal tube changes during days 2 and 3 in large burns—if the patient is already intubated—as this is typically the period of greatest edema formation, including laryngeal edema. Visualization of soot on the nares or vocal cords during laryngoscopy may suggest inhalational injury and consideration for leaving the endotracheal tube in post operatively is in order.

Physical examination of the burn patient should focus on the airway, cardiopulmonary exam, and associated mechanical challenges from the burns and the burn care. These include the scarring and restriction to head and neck structures from burn contractures, the potential for restrictive pulmonary physiology from torso scars, poor perfusion of digits, and the difficulties of mask ventilating and obtaining IV access in burn patients owing to the thermal injuries themselves and the dressings, lotions, and splints often found on burn patients.

1. What is the urgency of the surgery?

What is the risk of delay in order to obtain additional preoperative information?

Burn surgeries may be emergent, urgent, or elective. Typically, acute burn surgery is either emergent (escharotomies, airway management, vascular access) or urgent (excision and grafting), while reconstructive surgeries are usually elective.

Escharotomies: Resection of burn tissue that is compromising distal perfusion—or sometimes impairing ventilation—may be life- or limb-sparing surgery and needs to proceed without delay.

Airway management: Can present with life-threatening urgency in burn patients due to mechanical difficulties in maintaining a patent airway, and the patient's oxygen requirements may be compromised from inhalational injury, pulmonary edema, or restrictive pulmonary processes.

Vascular access can be extremely challenging in the burn patient and an operating room may be employed primarily to secure vascular access. In the initial acute phase, volume resuscitation is essential, as may be the need for exogenous vasoactive support, and thus vascular access is essential.

Excision and grafting, although essential for the treatment of large burns, is usually not emergent but urgent. Thus, it is imperative that cardiopulmonary status be optimized as much as possible (sometimes the burn is the source of sepsis, for instance, and excision is the required treatment) prior to going to the operating room.

Reconstructive surgeries: Can present with mechanical challenges to airway management but are rarely emergent or urgent. Thus, cardiopulmonary status should always be optimized in the preoperative period.

2. Preoperative evaluation

Preoperative evaluation must include a complete history and physical exam with special attention to systems typically affected by burn injuries. These include:

Airway: Patients with burns may have mechanical reasons for a very difficult airway including restrictions to mouth opening, edema formation, and laryngeal/tracheal abnormalities.

Neurologic: The patient may have had ischemic insults at the scene from hypoxia, CO poisoning, or apnea and unconsciousness at the scene prior to resuscitation. Cerebral edema must also be entertained as other systemic edemas manifest. Later, in the care of burn patients, delirium and posttraumatic stress disorders may manifest.

Cardiac: Cardiac output is dramatically reduced immediately after a burn and patients may require inotropic and chronotropic support. The heart may also be prone to injury from hypoxia, cyanide inhalation, and CO poisoning at the scene. Preexisting cardiac dysfunction/ischemia may be severely aggravated in the hypermetabolic phase of burn recovery when cardiac demand may increase several-fold.

Pulmonary:Inhalational injury of carbonaceous compounds, chemical injury (nitric acid and sulfuric acid are byproducts of the combustion of common synthetics), and thermal injuries (to the conducting portion of the respiratory tree) can all compromise pulmonary function. Additionally, the leaky vasculature in response to burn injury, combined with appropriate fluid resuscitation, may lead to pulmonary edema. Large alveolar-to-arterial gradients may exist, which then results in expired carbon dioxide values being lower than arterial carbon dioxide values.

Renal:Kidney function may be compromised shortly after injury due to myoglobinuria and hemoglobinuria. These may be special concern in an electrical burn with muscle damage and burns exceeding 40% of body surface area. Additionally, volume shifts, hypotension, and catecholamines (both endogenous and exogenous used for pressure support) may aggravate renal dysfunction. In the hypermetabolic phase, renal function may increase including more rapid elimination of anesthetic medications. A forced diuresis and alkalization of urine may be needed.

Hepatic:Liver perfusion may be compromised in the acute phase of the burn resulting in slower degradation of hepatically metabolized medications. In the hypermetabolic phase, the reverse occurs and drugs (classically opioids and muscle relaxants) are more rapidly metabolized and eliminated.

Hematologic: Initially, due to leaky vasculature, there may be a hemoconcentration seen. A thromobocytopenia may also be present in the early period. In the later (hypermetabolic phase) phase, platelet counts may increase dramatically but usually are not associated with clinical thrombotic events. There does appear to be a greater incidence of thrombosis of central lines in burn patients. It is not clear if this is from a hypercoagulable state or just the multiple lines these patients receive. The anemia of burns is related to decreased erythropoietin reduction as well as blood loss.

Gastrointestinal: In the acute phase, gastric emptying—and GI function in general—slows dramatically. These patients should be considered at risk for aspiration due to slow gastric emptying times. GI function resolves by about 72 hours. Prophylaxis for curling ulcers is mandatory .

Endocrine:A burn is a significant stressor to the body and the endocrine system responds appropriately. This may include hyperglycemia and relative insulin resistance, which may persist for months post burn. Multiple other hormones may be lower in the burn patient including thyroid hormones and testosterone; still other hormones are elevated in burn patients including cortisol, renin, angiotensin, and catecholamines.

Skin: The essential functions of the skin barrier, including temperature, fluid, and infection control, will be compromised in burn patients.

Medically unstable conditions warranting further evaluation include cardiopulmonary instability and airway management. Delaying surgery may be indicated if (1) the patient is so hemodynamically unstable, or with cardiopulmonary instability that transfers to/from the operating room, that surgery presents unacceptable risks. However, it must be emphasized that many burn injuries—specifically sepsis—may not improve without surgical intervention. (2) Airway management is not optimal. The airway of the burn patient may be one of the most challenging airways the anesthesiologist encounters. It is imperative that skilled personnel with appropriate airway equipment be present prior to inducing these patients.

3. What are the implications of co-existing disease on perioperative care?

Burn injury is dramatic stressor to every system of the body. Any coexisting disease process should be expected to be aggravated by the responses to burn injury. The following is a brief list:

  • CAD: Burns will place greater demands on the heart. Any preexisting cardiac disorder, including congenital heart disease, valvular heart disease, and coronary artery disease, will be exacerbated.

  • COPD: Inhalational injuries, infection, and vascular responses (pulmonary edema) will further aggravate pulmonary functions.

  • Hypertension: Renin and angiotensin levels are elevated -- in the hypermetabolic phase -- potentially aggravating hypertension. Fifty percent (50%) of children will exhibit hypertension at some point during their burn recovery and may require pharmacologic intervention.

  • Diabetes: Glycemic control may be challenging in the burn patient due to the function of elevated catecholamines and relative insulin insensitivity. Studies suggest that tighter glycemic control may decrease postoperative wound infections and urinary tract infections in these patients.

  • Renal disease: Kidneys are stressed in burn injury. Preexisting renal dysfunction may be aggravated.

  • Psychiatric: Burns create a physiological and psychological stress. Neuropsychiatric disorders, including depression and posttraumatic stress disorders, may be worsened.

Coexisting disease states will be aggravated in the burn patient.

Perioperative evaluation

If the procedure is elective, the patient's primary care physician should be included in the discussion that this patient is going for surgery. This is usually not feasible for patients in the acute phase of burn injury due to the emergent/urgent nature of the surgeries.

Perioperative risk reduction strategies

It is important to recognize the multitude of ways the burn patient may be affected and preexisting conditions aggravated, and then seek to optimize disorders preoperatively. Specific attention should be paid to the organ systems discussed under preoperative evaluation.

b. Cardiovascular system:

Cardiac output is dramatically reduced immediately after a burn and patients may require inotropic and chronotropic support. Hearts may also be prone to injury from hypoxia, cyanide inhalation, and CO poisoning at the scene.

Preexisting cardiac dysfunction/ischemia may be severely aggravated in the hypermetabolic phase of burn recovery when cardiac demand may increase several-fold. Maneuvers to decrease myocardial oxygen demand and cardiac work may be necessary. Bacteremia may occur during resection of burn tissue, resulting in significant cardiovascular dysfunction. It is recommended that vasopressors such as dopamine and epinephrine be readily available.

c. Pulmonary:

Inhalational injury of carbonaceous compounds, chemical injury (nitric acid and sulfuric acid are byproducts of the combustion of common synthetics), and thermal injuries (to the conducting portion of the respiratory tree) can all compromise pulmonary function. Additionally, the leaky vasculature in response to burn injury, combined with appropriate fluid resuscitation, may lead to pulmonary edema.

COPD: This will be aggravated by the burn. Consider optimizing respiratory care preoperatively and anticipate need for aggressive pulmonary toilet in the perioperative period.

Reactive airway disease (asthma): This may also be aggravated by the burn. All maneuvers used to treat reactive airway disease can be utilized in the care of the burn patient. We have found sevoflurane to be a useful volatile choice for the management of anesthesia in patients with reactive airways and burns due to its bronchodilatory properties.

Significant arterial-to-alveolar gradients for oxygen and carbon dioxide will exist.

c. Renal-GI:

Renal

Kidney function may be compromised shortly after injury due to myoglobinuria and hemoglobinuria. These may be especially of concern in an electrical burn with muscle damage or burns exceeding 40% of body surface area. Additionally, volume shifts, hypotension, and catecholamines (both endogenous and exogenous used for pressure support) may aggravate renal dysfunction. In the hypermetabolic phase, renal function may increase due to an increase in cardiac output, thus resulting in more rapid elimination of anesthetic medications. Renally excreted drugs include antibiotics (aminoglycosides, cephalosporins, penicillins, and quinolones), beta-blockers (atenolol, nadolol), digoxin, edrophonium, neostigmine, procainamide, pyridostigmine, and muscle relaxants (pancuronium and rocuronium).

GI

Hepatic

Initially after a burn, liver function is decreased. The liver may be damaged from hypoxemia and hypoperfusion or from toxic byproducts of the fire. In the hypermetabolic phase, hepatic blood flow and function may increase, presenting as more rapid metabolism of hepatically metabolized drugs. Common anesthetic medications metabolized by the liver include most volatile agents, muscle relaxants, narcotics, and barbiturates. These drugs may require modifications including increasing dosage and frequency.

Immediately post burn, gastric function (like other organs' functions) is depressed. This may manifest as a functional ileus, either gastric or intestinal. During the early phase of burn injury, gastric pH may be decreased and volume increased, thus increasing the risk for aspiration.

e. Neurologic:

The patient may have had ischemic insults from hypoxia, CO poisoning, or apnea and unconsciousness at the scene prior to resuscitation. Cerebral edema must also be entertained as other systemic edemas manifest. Later, in the care of burn patients, delirium and posttraumatic stress disorders may manifest.

Acute issues

In the acute phase, CNS injury may be present but not obvious. It is important that these are entertained and considered early on. Frequently these patients arrive already intubated and paralyzed. It is often difficult to know baseline CNS status preoperatively. Attention must be paid to the possibility of a catastrophic neurologic insult (e.g., status epilepticus, brainstem herniation, ischemic stroke, global hypoxic injury, cerebral edema) in the perioperative period and treat accordingly.

Chronic disease

Preexisting CNS disorders like epilepsy or prior stroke should be treated appropriately and the patient's maintenance medications continued in the perioperative period.

f. Endocrine:

A burn places significant physiological stress on the individual, and the endocrine system responds appropriately. This may include hyperglycemia and relative insulin resistance, which may persist for months post burn. Multiple other hormones may be lower in the burn patient, including thyroid hormones and testosterone; still other hormones are elevated in burn patients, including cortisol, renin, angiotensin, and catecholamines.

A patient with diabetes should be maintained on the glycemic regimen they routinely administer, assuming good preoperative control. It must be emphasized that glycemic control can be tumultuous in a diabetic patient status post burn due to the metabolic alterations, fluctuating catecholamine levels, and alterations in insulin sensitivity. Consultation with an endocrinologist and frequent intraoperative glucose checks are suggested.

g. Additional systems/conditions which may be of concern in a patient undergoing this procedure and are relevant for the anesthetic plan (e.g., musculoskeletal in orthopedic procedures, hematologic in a cancer patient)

N/A

4. What are the patient's medications and how should they be managed in the perioperative period?

It is important to recognize that oral absorption of medications preoperatively in burn patients may be altered by changes in gastric motility and function in the acute phase of burn injury.

h. Are there medications commonly seen in patients undergoing this procedure and for which should there be greater concern?

The burn patient should never receive a depolarizing muscle relaxant (i.e., succinylcholine) due to malignant hyperkalemia. This adverse response is present by the first 24 hours post burn injury. It can persist for years.

i. What should be recommended with regard to continuation of medications taken chronically?

Cardiac, pulmonary, renal, neurologic, and psychiatric medications should be taken as usual. Antiplatelet medications should be held as per other elective procedures.

j. How to modify care for patients with known allergies

Known drug allergies should be avoided as should depolarizing muscle relaxants (succinylcholine). There are many different anesthetic techniques, including volatile and TIVA, to facilitate safe and effective surgical anesthesia.

k. Latex allergy - If the patient has a sensitivity to latex (e.g., rash from gloves, underwear, etc.) versus anaphylactic reaction, prepare the operating room with latex-free products.

As burn patients will likely return to the operating room many times, it is prudent to routinely present a latex-free environment to these patients.

l. Does the patient have any antibiotic allergies - Common antibiotic allergies and alternative antibiotics

Antibiotic choices in burn patients are often determined by the organisms growing from the patient's wounds and what antibiotics they have been maintained on, in the acute care units. It is important to determine when the last doses of antibiotics were administered so as to avoid either overdosing or underdosing.

m. Does the patient have a history of allergy to anesthesia?

Malignant hyperthermia (MH)

Documented: Avoid all trigger agents such as succinylcholine and inhalational agents. Follow a proposed general anesthetic plan: total intravenous anesthesia with propofol ± opioid infusion ± nitrous oxide. Ensure an MH cart is available [MH protocol].

5. What laboratory tests should be obtained and has everything been reviewed?

  • CBC (complete blood count)

  • Electrolytes, including ionized calcium

  • ABG and/or CXR to evaluate and guide pulmonary function

  • Blood bank sample

  • Coagulation panel

Acute burns may have alterations in all these common laboratory studies:

  • CBC may have hemoconcentration in early acute phase followed by anemias; WBC alteration may be present and suggest sepsis (both elevated and abnormally low white counts may suggest sepsis).

  • Electrolytes may be altered due to volume shifts, hormonal responses, and renal dysfunction.

  • ABG and chest radiograph may be altered by pulmonary pathology.

  • Coagulation panel may be affected by the burn and hepatic and hematologic dysfunctions. Thrombocytopenia is common early on, and thrombocytosis is common during the hypermetabolic phase of injury (after days 3 to 5). A sudden drop in platelet count may reflect the onset of sepsis.

Intraoperative Management: What are the options for anesthetic management and how to determine the best technique?

Intraoperative anesthetic management is determined by several factors including the type of surgery and the functional status of the patient. For example, for excision and grafting, in the most common burn surgery, general anesthesia is almost always the preferred option, although regional and sedation with local anesthesia are potential alternatives. For this section, we will discuss, by anesthetic option, the burn surgeries that may be appropriate.

a. Regional anesthesia

Regional anesthesia can be used for excision and grafting as the primary anesthetic, providing both the donor area and burned region are able to be anesthetized via a regional technique. Usually, however, regional is a useful adjunct and employed primarily for postoperative pain control. Regional can be used when the burn is well localized (e.g., lower extremities). Regional often is not appropriate if areas for autograft are located on the head or upper torso.

Neuraxial

Benefits: Good postoperative pain control and usually not affected by hypermetabolic phase's rapid elimination of some analgesics. Additionally, it may decrease the hyperalgesia response that burn patients can get from opioids.

Drawbacks: Limited usefulness as primary anesthetic. Sometimes challenging to place if patient is diffusely burned. It may be contraindicated with ongoing sepsis.

Issues: It should not be placed in burned tissues due to risk of introducing infection into CNS.

Peripheral nerve block

Benefits: It is a useful technique for postoperative analgesia. Often we will use these blocks, sometimes with a catheter, to provide postoperative analgesia for the skin donor site.

Drawbacks: It has limited usefulness as a primary anesthetic. It is sometimes challenging to place if the patient is diffusely burned.

Issues: It should not placed in burned tissues due to risk of introducing infection into CNS.

b. General anesthesia

General anesthesia is the most common anesthetic for the management of burn patients.

Benefits: It is useful when burn injury is diffuse. Frequently large, disparate areas of tissue need to be excised and grafted, precluding a regional technique.

Drawbacks: These patients may be very sensitive to anesthetics in the acute phase and require pressors and other support to maintain cardiopulmonary stability.

Other issues: Avoid depolarizing muscle relaxants. Airway management may be very difficult. In the hypermetabolic phase, many drugs like muscle relaxants and intravenous anesthetics are rapidly metabolized and high tolerance may develop. The response to volatile anesthetic agents is similar to nonburn patients in the hypermetabolic phase.

Airway concerns: The burn patient may be the most challenging airway the anesthesiologist sees. Difficult airway management should always be anticipated in burn patients. Appropriate airway equipment including laryngoscopes, fiberoptic scopes, light wands, and surgical airway equipment should all be readily available.

c. Monitored anesthesia care is usually reserved for minor burn procedures like dressing changes and vascular access.

Monitored anesthesia care (MAC)

Benefits: There is potentially less hemodynamic stress than with general anesthesia.

Drawbacks: It may be challenging with potentially difficult airway management and cardiopulmonary instability, as often seen in burn patients.

Other issues: Intravenous anesthetic agents including opioids, hypnotics, and anxiolytics are often rapidly metabolized and eliminated in the hypermetabolic phase of burn injury.

6. What is the author's preferred method of anesthesia technique and why?

General anesthesia with neuraxial or peripheral nerve block to donor sites, if anatomically amenable.

What prophylactic antibiotics should be administered?

Typically these patients are on antibiotics preoperatively and we would maintain that regimen. If the patient is antibiotic naive, cefazolin would typically be used at 25 mg/kg IVP.

What do I need to know about the surgical technique to optimize my anesthetic care?

Important considerations for excision and grafting include the size of the area to be excised and potentially also the areas to be harvested. This is directly linked to how much blood loss can be anticipated. Additionally, if the surgeon is working on extremities, whether s/he uses tourniquets will affect blood loss as well.

What can I do intraoperatively to assist the surgeon and optimize patient care?

Have a detailed preoperative discussion, after performing the preop evaluation, with the surgeon. Preoperative concerns like airway management, volume status, and cardiopulmonary status are of concern to all members of the surgical/anesthesia team. Often the extent of the surgery can be minimized if patient condition warrants it.

What are the most common intraoperative complications and how can they be avoided/treated?

Prioritized by urgency:

Bleeding: This can be minimized with use of tourniquets and clysis (injecting dilute epinephrine 1:2,000,000) into excised and harvested areas.

Hemodynamic instability: Depending on acute versus hypermetabolic status of patient, they may need exogenous pressor support even without large fluid shifts. Sometimes the instability is secondary to infection and sepsis and supportive care (pressors, crystalloids, or colloids) may be necessary.

Pulmonary dysfunction: This can be due to underlying lung pathology but may also be aggravated by intraoperative fluid shifts.

Oliguria: As discussed, renal function may be compromised by the acute burn (e.g., myoglobinuria), as well as through resuscitative measures (catecholamines) and hormonal responses to the burn. It is important to monitor urine output and correlate with presumed volume status. Estimating volume status can be very challenging in these patients as urine output does not always reliably correlate with volume status (again due to injury of the burn and other factors mentioned above) but hypovolemia is certainly an additional stressor on the already stressed kidneys.

Complications

Cardiac complications may include ischemia, hypoperfusion, hypertension, and CHF.

Pulmonary complications may include pulmonary dysfunction secondary to inhalation injury, pulmonary edema in the acute phase, infectious causes, as well as mechanical obstruction to ventilation from carbonaceous material or other inhaled compounds.

Neurologically, the burn injured patient may have hypoxic encephalopathy, trauma, cerebral edema, hypoperfusion, or sepsis, as some of the reasons for CNS dysfunction. In extreme cases, the burn patient may already have had a catastrophic cerebral event (e.g., anoxic insult) during the fire, but not be stable enough to travel to MRI/CT for imaging studies. Often these patients are not emerged at the end of their procedures but kept intubated to the intensive care unit due to their high oxygen requirements or need for intense analgesia control.

Issues unique to this procedure

  • Volume injected of dilute epinephrine solution (epinephrine 0.5 mcg/mL) can be greater than a blood volume. This fluid is not inconsequential and must be considered in the patient's total "inputs."

  • Excision and grafting may be a very vascular procedure. Blood transfusions should be anticipated. Frequently, oozing in the postoperative period may be twice as much as bleeding intraoperatively.

  • Postoperative analgesia can be very challenging in the perioperative period. Typical analgesia doses may be much greater than seen with other patients, in the hypermetabolic phase. This is multifactorial and due to increased metabolism of opioids, larger volume of distribution, and development of tolerance at the opioid receptor level. We have found a multifaceted approach with opioids, anxiolytics, and adjunctive techniques such as dexmedetomidine, ketamine, or regional nerve block/catheters, to work well.

a. Neurologic:

N/A

b. If the patient is intubated, are there any special criteria for extubation?

Extubation considerations include "normal" extubation criteria but should also recognize the following:

Dynamic nature of burns. Temporal associations (e.g., how far out from burn injury) may result in leaky vasculature and diffuse edema making extubation inappropriate due to laryngeal and tracheal edema. There are patients who have been intubated without difficulty at the scene of a fire or in the emergency department but are not intubatable 3 days later.

Volume shifts in the perioperative setting may be significant and preclude extubation.

Analgesia requirements may preclude extubating these patients in the immediate postoperative period.

Pulmonary dysfunction may mean that ventilatory support is required postoperatively.

c. Postoperative management

What analgesic modalities can I implement?

Typically opioid and anxiolytic infusions are utilized for analgesia management. Often these are started already in the intensive care unit. If so, it is recommended that they be maintained and supplemented intraoperatively. It is also important to note that these infusions may provide the anesthesiologist with a useful guide for intraoperative bolusing. For example, if a patient is on a morphine infusion—preoperatively—of 5 mg/hr, then a reasonable bolus dose would be to start with 5 mg of morphine IV push.

What level bed acuity is appropriate?

Acutely burned patients having surgery should be recovered in a post-anesthesia care unit or dedicated acute care burn unit. For large areas of excision, these patients go directly back to the burn unit where they have plastic enclosures around the patient that serve as both a heat and an infection barrier.

What are common postoperative complications, and ways to prevent and treat them?

  • Bleeding: Follow hemodynamics, drainage from dressings, and recognize that significant oozing is likely to occur.

  • Pulmonary dysfunction: This may be multifactorial including burn pathology, volume shifts, and anesthesia. It is not uncommon for ventilatory support to be required in the immediate postoperative period when large areas are excised.

  • Analgesia: Excision of dead tissue may not be too stimulating (third-degree burns destroy the nerve ending in the cutaneous tissues) but the concomitant skin harvesting is very stimulating. This combined with the hypermetabolism of opioids and development of tolerance makes an appropriate analgesia regimen essential. As mentioned above, we like to maintain infusions of opioids and anxiolytics in the perioperative period, and use adjuncts such as dexmedetomidine, ketamine, and/or peripheral regional nerve blocks (on donor sites) to aid with analgesia management.

What's the Evidence?

Sheridan, RL, Szyfelbein, SK. "Trends in blood conservation in burn care". Burns. vol. 27. 2001. pp. 272-6.

(This is an important article on how to minimize blood loss in burn surgery.)

Shank, ES, Muth, CM. "Decompression illness, iatrogenic gas embolism, and carbon monoxide poisoning: the role of hyperbaric oxygen therapy". Int Anesthesiol Clin. vol. 38. 2000. pp. 111-38.

(Provides an approach to carbon monoxide poisoning, including treatment and hyperbaric oxygen therapy.)

Fuzaylov, G, Fidkowski, CW. "Anesthetic considerations for major burn injury in pediatric patients". Paediatr Anaesth. vol. 19. 2009. pp. 202-11.

(This is a useful review on the approach to burn care of pediatric patients.)

Martyn, JA, Richtsfeld, M. "Succinylcholine-induced hyperkalemia in acquired pathologic states: etiologic factors and molecular mechanisms". Anesthesiology. vol. 104. 2006. pp. 158-69.

(This is an important discussion of the intracellular mechanisms responsible for life-threatening potassium release in burn patient status post succinylcholine administration.)
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