Trauma
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Question 3 of 216
A 49 year old man is brought to ED following a gas explosion at his flat. He has full thickness burns to both legs and groin which you estimate to be about 20% TBSA. He weighs 70 kg. How much fluid should be prescribed in the first 8 hours?
Answer:
- Clinicians should provide burn resuscitation fluids for deep partial and full-thickness burns larger than 20% total body surface area (TBSA).
- The latest ATLS guidelines state that the initial fluid rate used for burn resuscitation has been updated by the American Burn Association to reflect concerns about over-resuscitation when using the traditional Parkland formula. The current consensus guidelines state that fluid resuscitation should begin at 2 ml of lactated Ringer’s x patient’s body weight in kg x % TBSA.
- Fluid resuscitation = 2 mL x 70 kg x 20% = 2800 mL over 24 hours = 1400 mL over first 8 hours.
- One-half of the total fluid is provided in the first 8 hours after the burn injury and the remaining one-half of the total fluid is administered during the subsequent 16 hours.
Burns: Initial Resuscitation
Trauma
Last Updated: 28th August 2021
Life-saving measures for patients with burn injuries include stopping the burning process, ensuring that airway and ventilation are adequate, and managing circulation by gaining intravenous access.
Stopping the burning process
- Stop the burning process (for example extinguish flames using 'drop and roll' or smother them with a blanket). Completely remove the patient’s clothing to stop the burning process; however, do not peel off adherent clothing. Synthetic fabrics can ignite, burn rapidly at high temperatures, and melt into hot residue that continues to burn the patient.
- Exercise care when removing any clothing that was contaminated by chemicals. Brush any dry chemical powders from the wound. After removing the powder, decontaminate the burn areas by rinsing with copious amounts of warm saline irrigation or rinsing in a warm shower when the facilities are available and the patient is able.
- Once the burning process has been stopped, cover the patient with warm, clean, dry linens to prevent hypothermia.
- If possible, within 20 minutes of the injury, irrigate the burn with cool or tepid running water for 20–30 minutes. Do not use ice or very cold water, as this may cause vasoconstriction and may deepen the wound. If water is not available, use wet towels or compresses. Do not apply cold water to a patient with extensive burns (i.e. > 10% TBSA). Ensure the person is kept warm with coats, sheets, or blankets to avoid hypothermia, especially if cooling large areas of skin in children and the elderly. Immediately after cooling, cover the burn using cling film or a clean, cotton sheet. Do not use wet dressings or topical creams. Elevate the affected area if possible, to reduce the risk of oedema.
Establishing airway control
- The airway can become obstructed not only from direct injury (e.g. inhalation injury) but also from the massive oedema resulting from the burn injury. Oedema is typically not present immediately, and signs of obstruction may initially be subtle until the patient is in crisis. A history of confinement in a burning environment or early signs of airway injury on arrival in the emergency department (ED) warrants evaluation of the patient’s airway and definitive management.
- Factors that increase the risk for upper airway obstruction are:
- Increasing burn size and depth
- Burns to the head and face
- Inhalation injury
- Associated trauma
- Burns inside the mouth
- The clinical manifestations of inhalation injury may be subtle and frequently do not appear in the first 24 hours. If the provider waits for x-ray evidence of pulmonary injury or changes in blood gas determinations, airway oedema can preclude intubation, and a surgical airway may be required. When in doubt, examine the patient’s oropharynx for signs of inflammation, mucosal injury, soot in the pharynx, and oedema, taking care not to injure the area further. A carboxyhaemoglobin level greater than 10% in a patient who was involved in a fire also suggests inhalation injury.
- American Burn Life Support (ABLS) indications for early intubation include:
- Signs of airway obstruction (hoarseness, stridor, accessory respiratory muscle use, sternal retraction)
- Extent of the burn (total body surface area burn > 40%–50%)
- Extensive and deep facial burns
- Burns inside the mouth
- Significant oedema or risk for oedema
- Difficulty swallowing
- Signs of respiratory compromise: inability to clear secretions, respiratory fatigue, poor oxygenation or ventilation
- Decreased level of consciousness where airway protective reflexes are impaired
- Anticipated patient transfer of large burn with airway issue without qualified personnel to intubate en route
- Transfer to a burn center is indicated for patients suspected of experiencing inhalation injury; however, if the transport time is prolonged, intubate the patient before transport. Stridor may occur late and indicates the need for immediate endotracheal intubation.
- Circumferential burns of the neck can lead to swelling of the tissues around the airway; therefore, early intubation is also indicated for full thickness circumferential neck burns. It is important to place an appropriately sized endotracheal tube (ETT), as placing a tube that is too small will make ventilation, clearing of secretions, and bronchoscopy difficult or impossible.
Ensuring adequate ventilation
Direct thermal injury to the lower airway is very rare and essentially occurs only after exposure to superheated steam or ignition of inhaled flammable gases. Breathing concerns typically arise from three general causes: hypoxia, carbon monoxide poisoning, and smoke inhalation injury:
Hypoxia
- Hypoxia may be related to inhalation injury, poor compliance due to circumferential chest burns, or thoracic trauma unrelated to the thermal injury.
- In these situations, administer supplemental oxygen with or without intubation.
- If the patient’s haemodynamic condition permits and spinal injury has been excluded, elevate the patient’s head and chest by 30 degrees to help reduce neck and chest wall oedema.
- If a full-thickness burn of the anterior and lateral chest wall leads to severe restriction of chest wall motion, even in the absence of a circumferential burn, chest wall escharotomy may be required.
Carbon monoxide poisoning
- Always assume carbon monoxide (CO) exposure in patients who were burned in enclosed areas.
- The diagnosis of CO poisoning is made primarily from a history of exposure and direct measurement of carboxyhaemoglobin (HbCO).
- Patients with CO levels of less than 20% usually have no physical symptoms. Higher CO levels can result in headache and nausea (20-30%), confusion (30-40%), coma (40-60%) and death (>60%).
- Cherry-red skin color in patients with CO exposure is rare, and may only be seen in moribund patients.
- Due to the increased affinity of haemoglobin for CO (240 times that of oxygen), it displaces oxygen from the haemoglobin molecule and shifts the oxyhaemoglobin dissociation curve to the left. CO dissociates very slowly, and its half-life is approximately 4 hours when the patient is breathing room air. Because the half-life of HbCO can be reduced to 40 minutes by breathing 100% oxygen, any patient in whom CO exposure could have occurred should receive high-flow (100%) oxygen via a non-rebreathing mask.
- Arterial blood gas determinations should be obtained as a baseline for evaluating a patient’s pulmonary status. However, measurements of arterial PaO2 do not reliably predict CO poisoning, because a CO partial pressure of only 1 mm Hg results in an HbCO level of 40% or greater. Therefore, baseline HbCO levels should be obtained, and 100% oxygen should be administered.
- If a carboxyhaemoglobin level is not available and the patient has been involved in a closed-space fire, empiric treatment with 100% oxygen for 4 to 6 hours is reasonable as an effective treatment for CO poisoning and has few disadvantages. An exception is a patient with chronic obstructive lung disease, who should be monitored very closely when 100% oxygen is administered.
- Pulse oximetry cannot be relied on to rule out carbon monoxide poisoning, as most oximeters cannot distinguish oxyhaemoglobin from carboxyhaemoglobin. In a patient with CO poisoning, the oximeter may read 98% to 100% saturation and not reflect the true oxygen saturation of the patient, which must be obtained from the arterial blood gas. A discrepancy between the arterial blood gas and the oximeter may be explained by the presence of carboxyhaemoglobin or an inadvertent venous sample.
- There is no role for hyperbaric oxygen therapy in the primary resuscitation of a patient with critical burn injury. Once the principles of ATLS are followed to stabilise the patient, consult with the local burn center for further guidance regarding whether hyperbaric oxygen would benefit the patient.
Inhalation injury
- Products of combustion, including carbon particles and toxic fumes, are important causes of inhalation injury. Smoke particles settle into the distal bronchioles, leading to damage and death of the mucosal cells. Damage to the airways then leads to an increased inflammatory response, which in turn leads to an increase in capillary leakage, resulting in increased fluid requirements and an oxygen diffusion defect. Furthermore, necrotic cells tend to slough and obstruct the airways. Diminished clearance of the airway produces plugging, which results in an increased risk of pneumonia.
- Cyanide inhalation from the products of combustion is possible in burns occurring in confined spaces, in which case the clinician should consult with a burn or poison control center. A sign of potential cyanide toxicity is persistent profound unexplained metabolic acidosis.
- Not only is the care of patients with inhalation injury more complex, but their mortality is doubled compared with other burn injured individuals.
- The American Burn Association has identified two requirements for the diagnosis of smoke inhalation injury: exposure to a combustible agent and signs of exposure to smoke in the lower airway, below the vocal cords, seen on bronchoscopy. The likelihood of smoke inhalation injury is much higher when the injury occurs within an enclosed place and in cases of prolonged exposure.
- As a baseline for evaluating the pulmonary status of a patient with smoke inhalation injury, clinicians should obtain a chest x-ray and arterial blood gas. These values may deteriorate over time; normal values on admission do not exclude inhalation injury.
- The treatment of smoke inhalation injury is supportive. A patient with a high likelihood of smoke inhalation injury associated with a significant burn should be intubated.
Managing the circulation
Evaluation of circulating blood volume is often difficult in severely burned patients, who also may have accompanying injuries that contribute to hypovolemic shock and further complicate the clinical picture. Treat shock according to usual resuscitation principles with the goal of maintaining end organ perfusion. In contrast to resuscitation for other types of trauma in which fluid deficit is typically secondary to haemorrhagic losses, burn resuscitation is required to replace the ongoing losses from capillary leak due to inflammation.
Establishing IV access
- After establishing airway patency and identifying and treating life-threatening injuries, immediately establish intravenous access with two large-caliber (at least 18-gauge) intravenous lines in a peripheral vein.
- If the extent of the burn precludes placing the catheter through unburned skin, place the IV through the burned skin into an accessible vein.
- The upper extremities are preferable to the lower extremities as a site for venous access because of the increased risk of phlebitis and septic phlebitis when the saphenous veins are used for venous access.
- If peripheral IVs cannot be obtained, consider central venous access or intraosseous infusion.
- Be aware that resulting oedema can dislodge peripheral intravenous lines. Consider placing longer catheters in larger burns.
Calculating initial fluid resuscitation
- Clinicians should provide burn resuscitation fluids for deep partial and full-thickness burns larger than 20% total body surface area (TBSA).
- The initial fluid rate used for burn resuscitation has been updated by the American Burn Association to reflect concerns about over-resuscitation when using the traditional Parkland formula. Current guidelines recommend that:
- Fluid resuscitation should begin at 2 ml of lactated Ringer’s x patient’s body weight in kg x % TBSA for second- and third-degree burns.
- One-half of the total fluid is provided in the first 8 hours after the burn injury and the remaining one-half of the total fluid is administered during the subsequent 16 hours.
Continuing fluid resuscitation
- It is important to understand that formulas provide a starting target rate but the actual fluid rate that a patient requires depends on the severity of injury, because larger and deeper burns require proportionately more fluid. Inhalation injury also increases the amount of burn resuscitation required.
- Following initial fluid resuscitation, the amount of fluids provided should be adjusted based on a urine output target of 0.5 mL/kg/hr for adults. Urine output should be maintained between 30 and 50 mL/hr to minimise potential over-resuscitation.
- If the initial resuscitation rate fails to produce the target urine output, increase the fluid rate until the urine output goal is met. However, do not precipitously decrease the IV rate by one-half at 8 hours; rather, base the reduction in IV fluid rate on urine output and titrate to the lower urine output rate. Fluid boluses should be avoided unless the patient is hypotensive. Low urine output is best treated with titration of the fluid rate.
- It is important to understand that under-resuscitation results in hypoperfusion and end organ injury. Over-resuscitation results in increased oedema, which can lead to complications, such as burn depth progression or abdominal and extremity compartment syndrome. The goal of resuscitation is to maintain the fine balance of adequate perfusion as indicated by urine output.
Monitoring resuscitation
- Insert an indwelling urinary catheter in all patients receiving burn resuscitation fluids, and monitor urine output to assess perfusion.
- Cardiac dysrhythmias may be the first sign of hypoxia and electrolyte or acid-base abnormalities; therefore, electrocardiography (ECG) should be performed for cardiac rhythm disturbances.
- Persistent acidaemia in patients with burn injuries may be multifactorial, including under-resuscitation or infusion of large volumes of saline for resuscitation.
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
