MAJ Jacob Swann, MD and William Mohr, III, MD Regions Hospital, Saint Paul, MN, USA Calculating total body surface area (TBSA) for burns is critical to adequate resuscitation following injury. TBSA involvement dictates whether a patient needs intravenous (IV) fluid resuscitation, protocolized resuscitation via a burn formula (e.g. the Parkland formula, USAISR calculator, or Burn Navigator system), and acts as a guide for severity of injury. Calculation of TBSA is performed by using the “rule of nines.” Chest: 18% Back: 18% Right upper extremity (RUE): 9% Left upper extremity (LUE): 9% Right lower extremity (RLE): 18% Left lower extremity (LLE): 18% Head: 9% Perineum: 1% Only superficial partial thickness, deep partial thickness, and full thickness burns are counted in the “rule of 9s.” Red skin that is not blistered (i.e. superficial burns) are not counted. For burns that don’t encompass the whole 9% allotted, a provider measures the palmer surface of the patient’s hand and uses this size as an estimate of 1% TBSA. In our stem, the patient has superficial burns of the anterior half of the face (0% TBSA), superficial partial thickness burns of the anterior chest (18% TBSA), deep partial thickness burns of the anterior BLE (9% on the RLE and 9% on the LLE), and circumferential full thickness burns of the RUE (9% TBSA). Therefore, the patient has 0 + 18 + 9 + 9 + 9 = 45% TBSA. Answer: D Pham TN, et al. Advanced Burn Life Support Course: Provider Manual 2018 Update. Chicago, IL. American Burn Association. 2018. Patients with large TBSA burns (>20%) require IV fluid resuscitation and choosing an initial fluid type and rate is critical. The systemic inflammatory response leads to systemic capillary leakage and loss of vascular oncotic pressure. Interstitial edema causes changes in the structural proteins leading to less resistance to further edema. Both under‐ and over‐resuscitation of burns can promote conversion of partial thickness burns to full thickness burns, burn shock, and end‐organ damage. Anasarca can result in extremity and abdominal compartment syndrome with mortality rates as high as 80% in burn patients. Major burn resuscitation will require large volumes of crystalloid fluid. The important difference between LR and NS is the chloride content; LR has 109 mEq/L, while NS has 154 mEq/L. Even 3–5 L of NS can produce hyperchloremic metabolic acidosis, as bicarbonate shifts intracellularly to maintain electric neutrality throughout the body. Due to the large volumes needed in burn resuscitation, NS is contraindicated due to the high risk of developing a hyperchloremic metabolic acidosis compromising the patient’s likely strained metabolic status. LR is the preferred resuscitation formula for this patient. Thus, answers B and D are incorrect. The calculation of the initial fluid rates for burned patients is a topic of debate. But recently the American Burn Association (ABA) has endorsed a consensus formula utilizing the most beneficial aspects of the Parkland and modified Brooke formulae. This formula is now taught in both the Advanced Burn Life Support and Advanced Trauma Life Support programs. The ABA formula uses the patient’s body weight and TBSA to estimate their 24‐hour fluid requirement with the starting rate half of the traditional Parkland formula: Initial rate = 2 mL/hr * body weight in kg * TBSA divided by 16. This is because the physiologic fluid requirements are not linear with time; they create a Bell‐shaped curve that is shifted toward the early resuscitation period making more volume needed up front than at the end of the initial 24‐hour resuscitation period. Burn patients need roughly half of their resuscitation volume over an 8‐hour period between hours 4 and 12 postburn. In our example, the patient’s body weight is 100 kg and TBSA is 40%. The initial fluid rate is: 2 * 100 kg * 40 = 8000 mL as the estimated 24‐hour fluid requirement. 8 L/16 (this is half of the volume divided by 8 per the initial Parkland calculation) is 500 mL/h as the starting rate. Although older teaching tried to make up or reduce fluid rates based upon volumes given prior to admission, the capillary fluid loss does not allow for fluid already given or not given to be made up or carried forward. For instance, you cannot give our patient 8 L over 4 hours and expect them to not need further fluids for the next 4 hours. In our patient, the volume of resuscitation was 500 mL/h and would not change your calculations. Answer: A Greenhalgh DG. Burn resuscitation: the results of the ISBI/ABA survey. Burns. 2010; 36 (2): 176–182. Pham TN, et al. Advanced Burn Life Support Course: Provider Manual 2018 Update. Chicago, IL. American Burn Association. 2018. End‐markers of resuscitation can be misleading during burn resuscitation in that traditional markers can be normal or improved from presentation while total body volume status is relatively low. When inadequate resuscitation occurs, partial thickness burns can convert to deep burns. Moreover, burn shock can occur due to progressive third‐space fluid sequestration later in the course of the initial burn resuscitation. Conversely, over‐resuscitation also leads to downstream consequences with development of abdominal compartment syndrome, conversion of partial thickness burns to deep burns, and anasarca. Given this, it is important to achieve appropriate resuscitation without over‐ or under‐resuscitating. Tachycardia can be elevated persistently due to pain from burns and—if used to guide resuscitation—could lead to over‐resuscitation as fluid rates are increased in the face of a heart rate that is not responding to expanded intravascular volumes. Similarly, blood pressure can often be maintained early in a resuscitation even if inadequate resuscitation is initiated. It is not until burn shock develops 24–48 hours after presentation that blood pressure issues will likely arise. Serum lactate can be elevated for many reasons in a burn patient (i.e. carbon monoxide poisoning, cyanide toxicity, burn shock); therefore, normalization of the lactate should not be used to determine if a patient is adequately resuscitated. Moreover, trending lactates on an hourly basis to guide IV fluid resuscitation rates is not supported by the American Burn Association or Advanced Burn Life Support. For similar reasons, normalization of the base deficit is not appropriate to guide adequacy of resuscitation as this may be falsely elevated from pathologies that have nothing to do with the patient’s fluid status. Similarly, a normal base deficit should not prompt decreasing IV fluid rates. As such, these traditional end‐point markers used in other ICUs to guide resuscitation are inadequate or inappropriate to use for hourly titration of fluid resuscitation. Urine output (UOP) of 0.5 mL/kg/hr is the most sensitive and appropriate end point to guide resuscitation. UOP should be followed hourly, and IVF titrated based on UOP. Answer: A Guilabert P, Usua G, Matin N, et al. Fluid resuscitation management in patients with burns: update. British Journal of Anaesthesia. 2016; 117 (3): 284–296. Pham TN, Cancio LC, and Gibran NS. “American burn association practice guidelines burn shock resuscitation. Journal of Burn Care and Research. 2008; 29 (1): 257–266. The patient presents following a house fire with prolonged extraction from the building and has suffered an inhalational injury. Edema of the upper airways and vocal cords causes the hoarse voice. Carbonaceous sputum is due to inhalation of particulate matter from incompletely burned materials. This matter builds in the lower airways causing copious amounts of secretions. Wheezing is consistent with mucus narrowing the bronchioles of the lower airways. Lastly, incomplete combustion of carbon and nitrogen‐based materials produce carbon monoxide, hydrogen cyanide, and other toxic gases. With exposure to these gases, patients develop altered mental status due to poor oxygen delivery and utilization within the cells of the central nervous system demonstrated by altered mental status. With a clinical diagnosis of inhalational injury producing symptoms of respiratory distress, proceeding with intubation is most appropriate for this patient. Performing a tracheostomy within 24 hours is not appropriate at this time. In a recent survey of burn centers, the average time to tracheostomy was approximately 2 weeks. Some patients with severe head and neck burns will progress more quickly to a surgical airway, but this patient has none of these indications. There is no role for systemic corticosteroids in the treatment of inhalational injury. While data on the optimal ventilator management of burned and inhalation injury patients is limited, consensus across burn centers is to use ARDSNet‐style ventilation with low tidal volumes (LTV) to limit ventilator‐associated lung injury. It is important to note that, due to fibrin casts, extensive chest wall thermal injuries, or high volumes of fluid resuscitation, LTV strategies can be ineffective in the burn population. After suffering an inhalational injury, patients will require a large volume of resuscitation in their initial hospital course. While some patients with smoke inhalation require increased fluid volumes, targeting 0.3–0.5 mL/kg/hr of urine output remains the goal in these patients. The surgical intensivist should be aware that the amount of IV fluids may exceed that predicted by standard formula in these patients. Answer: D Dries DJ and Endorf FW. Inhalation injury: epidemiology, pathology, and treatment strategies. Scandanavian Journal of Trauma, Resuscitation, and Emergency Medicine. 2013; 21: 31–46. Chung KK, et al. A survey of mechanical ventilator practices across burn centers in North America. Journal of Burn Care and Research. 2016; 37: e131–e139. Walker PF, et al. Diagnosis and management of inhalation injury: an updated review. Critical Care. 2015; 19: 351–363. pH: 6.9 PaO2: 280 PaCO2: 30 HCO3‐: 12 Lactate: 16 What is the most appropriate treatment for her acidosis? Cyanide toxicity is an uncommon presenting issue outside of industrial accidents, wartime casualties, and house fires. Cyanide is liberated from nitrogen‐containing polymers when ignited; both natural (wool, silk, paper) and synthetic (nylon, polyvinyl chloride) sources can release cyanide. Cyanide causes cellular asphyxia by blocking the electron transport chain in the mitochondria of the cells, preventing oxidative phosphorylation with resultant anaerobic metabolism throughout the body. This causes a markedly elevated lactate and glucose resulting in profound metabolic acidosis. Urgent reversal of this is required to restart ATP generation. High‐dose hydroxycobalamin is the preferred agent to correct this. The dosing is 5 mg of hydroxycobalamin IV, and it may be repeated once. Less preferred agents are sodium thiosulfate or sodium nitrite. Increasing the LR infusion rate, changing LR to bicarbonate, increasing the respiratory rate, or starting hemodialysis will not affect the root cause of the patient’s metabolic acidosis. Answer: E MacLennan L and Moiemen N. Management of cyanide toxicity in patients with burns. Burns. 2015; 41 (1): 18–24. Walker PF, et al. Diagnosis and management of inhalation injury: an updated review. Critical Care. 2015; 19: 351–363. Anseeuw K, Delvau N, Burillo‐Putze G, et al. Cyanide poisoning by fire smoke inhalation: a European expert consensus. European Journal of Emergency Medicine. 2013; 20
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Burns, Inhalational Injury, and Lightning Injury
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