Advanced Trauma Life Support ATLS Student Course Manual 2018

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CHAPTER 9 n Thermal Injuries
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 hemoglobin for CO—240
times that of oxygen—it displaces oxygen from the
hemoglobin molecule and shifts the oxyhemoglobin
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.
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. Efforts should
be made to use endotracheal tubes at least 7.5 mm ID
or larger in an adult and size 4.5 mm ID ETT in a child.
Arterial blood gas determinations should be obtained
as a baseline for evaluating a patient’s pulmonary
status. However, measurements of arterial PaO 2
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 carboxyhemoglobin 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 oxyhemoglobin from carboxyhemoglobin.
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 carboxyhemoglobin
or an inadvertent venous sample.
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.
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
stabilize the patient, consult with the local burn center
for further guidance regarding whether hyperbaric
oxygen would benefit the patient.
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. 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
determination. 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 (i.e.,
greater than 20% total body surface area [TBSA] in an
adult, or greater than 10% TBSA in patients less than
10 or greater than 50 years of age) should be intubated.
If the patient’s hemodynamic 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 edema. 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.
Manage Circulation with Burn
Shock Resuscitation
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 the resuscitation principles
outlined in Chapter 3: Shock, 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 hemorrhagic losses, burn
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