Similarly, the following considerations surrounding resuscitative strategies should be employed and are temporally bound:

1. First 24 Hours: Expect massive fluid shifts in both burned and nonburned tissues in patients with more than 20% TBSA burns. Release of proinflammatory mediators such as TNF-α, histamine, and leukotrienes leads to increased microvascular permeability, edema, and shock. In general, resuscitation should be considered in adult patients who have greater than or equal to 20% TBSA burns and pediatric patients who have greater than or equal to 15% TBSA burns. It is important to begin resuscitation via two large-bore peripheral IVs. The initial adjusted fluid rate includes lactated Ringer at 2 to 4 mL × kg × %TBSA (dependent on mechanism) burn with half the volume given in the first 8 hours of injury (not arrival) and the second half given in the subsequent 16 hours. Adult, nonelectrical injury burns should be given 2 mL × kg × % TBSA and pediatric (<14 years old), nonelectrical injury burns should be given 3 mL × kg × % TBSA. All patients, regardless of age, should be given 4 mL × kg × % TBSA burns. Children weighing less than 30 kg do not have large liver glycogen stores and should receive 0.45% saline with 5% dextrose at maintenance rate in addition to resuscitative fluid (Table 33.1). Colloid (5% albumin) can be added to the resuscitation fluids if the resuscitation rate approaches 6 mL/kg/%TBSA. This can be done by adding albumin in a 3:1, 2:1, or 1:1 ratio of colloid:crystalloid to equal the total adjusted fluid volume.
1. During resuscitation, it is imperative to follow the clinical response by monitoring urine output, lactate, base deficit, and, perhaps, cardiac output/index and stroke volume variation if using PiCCO^® or FloTrac^®. It is recommended to maintain urine output of 0.5 mL/kg/h in adults and 1.0 mL/kg/h in kids. However, urine output can lag behind resuscitation and care must be taken not to overresuscitate. IV fluid adjustments are made by increasing the rate by one-third if the urine output is below the calculated goal urine output by more than one-third. The IV fluid rate should be decreased by one-third if the urine output is above the calculated goal urine output by more than one-third. Studies do not necessarily demonstrate improved outcomes with either of these devices. PA catheters may lead to overresuscitation in healthy patients but are helpful in patients with cardiac diseases and those at risk for cardiac shock and congestive heart failure.
2. It is important to assess for the presence of compartment syndrome of the extremities. This is done by serial neurovascular examinations. Monitoring for abdominal compartment syndrome should also be done. This is performed by transducing bladder pressures. There should be heightened suspicion for abdominal compartment syndrome if there is increased difficulty ventilating and oxygenating, hypotension, and oliguria (due to decreased venous return). Ocular compartment syndrome can be assessed using a tonometer.
2. Second 24 Hours: All patients should receive crystalloid to maintain urine output and to maintain parameters of perfusion. Monitoring for adequacy of perfusion can be done by measuring lactate, pulse or stroke volume variation, and cardiac outputs. Nutritional support should be started, usually by employing enteral nutrition as soon as possible; ideally within 6 hours of injury. After 24 to 36 hours, IV fluids can be decreased by one-third, as long as the patient continues to produce adequate urine. IV fluids can again be decreased by one-third for hours 36 to 48 (as long as urine output is maintained). Colloids can be given after initial crystalloid resuscitation (5% albumin at 0.3-0.5 mL/kg/%TBSA over 24 hours) if blood pressure or urine output is not adequate.
3. After 48 Hours, IV fluid should be administered to maintain urine output at 0.5 to 1 mL/kg body weight/h. Insensible losses and hyperthermia are associated with a hyperdynamic state. Daily weights can be helpful to determine insensible fluid loss or fluid retention.
4. Overresuscitation: If during the first 24 hours, resuscitation exceeds 6 mL/kg/ %TBSA burn/24 h, the physician should reassess the clinical picture. An exuberant administration of IV fluid can lead to abdominal or extremity compartment syndrome with decreased chest wall compliance leading to elevated peak airway pressures. Hourly neurovascular exams should be performed of all extremities at risk. Because patients are frequently intubated, physical exams can be limited. However, capillary refills can be assessed, as can pulse oximetry and compartment pressures with a Stryker needle or arterial line setup. If circumferential eschar is causing concern about compartment syndrome, extremity escharotomy should be performed. This includes making an incision along the lateral and medial aspects of the affected extremities. These incisions are down through the dermis only, exposing the underlying subcutaneous fat (Figure 33.3). Avoid incisions into the subcutaneous tissue and do not cut through the muscle or muscular fascia (Figure 33.4).
1. Chest compartment syndromes: The diagnosis is based on decreased chest wall compliance and increased peak airway pressures in the presence of circumferential or near-circumferential deep burns about the chest. Chest escharotomy should be performed along the anterior axillary line and connected at the subcostal lines.
2. Abdominal compartment syndrome: The diagnosis is based on exam and bladder pressure greater than 30 mm Hg. Patients may have hypotension, oliguria, and/or increased minute ventilation. Escharotomies laterally can also help prevent abdominal compartment syndrome. Once present, however, a bedside decompressive laparotomy may be needed, especially if high bladder pressures and high peak airway pressures remain after completion of the escharotomy.
3. Orbital compartment syndrome is relieved with lateral canthotomy.