Airway and Breathing Assessment and Management
The airway and breathing are assessed and a decision made concerning the need for endotracheal intubation. Upper airway inhalation injury is usually due to a heat injury that leads to swelling and upper airway obstruction secondary to edema of the posterior pharynx and supraglottic regions. Inhalation airway injury can occur after the inhalation of superheated air or steam and other toxic compounds found in smoke. Inhalation injury is suspected in any patient exposed to smoke in an enclosed space (Table 8.2. A).
Table 8.2A. Predictive indicators of an inhalation injury
- History of a closed-space fire
- Impaired mental status
- Loss of consciousness
- Associated drug or alcohol use
- Facial burns
- Airway soot
- Singed nasal hair
- Abnormal findings on nasal or laryngotracheal air way
- Airway edema
- Carbonaceous material in the airway
Table 8.2B. Indication for immediate tracheal intubation
- Cardiovascular instability
- Central nervous system depression
- Massive burns greater than 60% of total body surface area
- Symptoms of impending airway obstruction
Patients with significant burns to the face and neck are at increased risk of airway injury (Figure 8.3). Signs that are highly indicative of smoke exposure include facial burns, airway soot (black powder), carbonaceous sputum, and singed (burnt) nasal hair. Patients with increasing respiratory rate, increased secretions, stridor, dyspnea, use of accessory muscles, dysphagia, and progressive hoarseness have likely sustained significant inhalational injury and require emergent tracheal intubation because of impending airway obstruction (Table 8.2.B). It is important to note that a patient with minimal airway distress should be questioned as to the events associated with the burn, the patient's name and information, medical history, allergies, surgical history, medications, and other pertinent information prior to manipulation of the airway. Chemicals such as plastics, wool, paper, charcoal present in smoke can also directly irritate the respiratory epithelium.
Carbon monoxide is produced by the combustion of organic material, and carbon monoxide poisoning may accompany smoke exposure. Carbon monoxide has high affinity to binds with hemoglobin preventing combination of hemoglobin with oxygen. Pulse oximetry is inaccurate in the presence of carboxyhemoglobin because it is interpreted as saturated hemoglobin. The severity of the poisoning depends on the proportion of hemoglobin combined with carbon monoxide. Symptoms range from a throbbing headache with nausea and vomiting to coma, convulsions and cardiac arrest. 100% oxygen is the initial treatment and may necessitate intubation and ventilation.
Assessment and Management of Circulation
After the evaluation and treatment of disorders of the airway and breathing, the circulation must be assessed. Peripheral pulses may be weak or absent due to under resuscitation or proximal circumferential third degree burns. Tachycardia is common and may be due to primarily pain, and hypovolemic shock. Large peripheral intravenous access should be obtained, preferably in areas of unburned skin. Intravenous fluid should consist of lactated Ringer's solution.
All of the various formulas used to estimate the amounts of fluid to be given to a burn patient are based on the total body surface area (TBSA) burned.
The most widely used formula to estimate the initial fluid requirements for a burned patient is the Parkland Formula. The 24-hour fluid requirement is estimated based on the formula:
4 mL/kg per percent TBSA burned. Half of this amount of fluid is given in the first 8 hours following the burn with the remainder given over the next 16 hours. For example, a 50-kg male receives burns covering 80 percent of his body. The formula 4(50)(80) = 16,000. The 16 L of estimated fluid are divided such that 8 L are given over the initial 8 hours following burn injury. Thus, the starting IV rate of lactated Ringer's solution is 2,000 mL/hr. This example also emphasizes the complications that can occur if this volume of normal saline solution were to be administered. For children, the calculation of initial fluid requirement is more complex. A maintenance rate of D5 lactated Ringer's solution should be administered continuously. In addition, 3mL/kg per percent burn of lactated Ringer's without glucose should be administered, half of this amount in the initial 8 hours and half over the subsequent 16 hours.