Prophylaxis against Aspiration of Gastric Contents
A trauma patient is always considered to have a full stomach and
to be at risk for aspiration during induction of anesthesia (also see Chapter
58
and Chapter 68
).
Reasons for this status include ingestion of food or liquids before the injury,
swallowed blood from oral or nasal injuries, delayed gastric emptying associated
with the stress of trauma, and administration of liquid contrast medium before abdominal
CT scanning. If time and patient cooperation allow, it is reasonable to administer
nonparticulate antacids to a trauma patient before induction and intubation.
Cricoid pressure—the Sellick maneuver—should be applied
continuously during emergency airway management from the time that the patient loses
protective airway reflexes until endotracheal tube placement and cuff inflation are
confirmed. In the traditionally defined rapid-sequence induction, any attempt at
ventilation between administration of medication and intubation is avoided, presumably
because positive-pressure ventilation may force gas into the patient's stomach and
lead to regurgitation and aspiration. The reasoning for this sequence is unclear
inasmuch as appropriate application of cricoid pressure should prevent any air entry
into the esophagus. Indeed, Sellick's original paper described ventilation during
cricoid pressure in patients with full stomachs.[16]
Furthermore, an increase in oxygen consumption in trauma patients necessitates preoxygenation
whenever possible, and because preoxygenation may be difficult in a trauma patient
as a result of facial trauma, decreased respiratory effort, or agitation, desaturation
will occur rapidly.
*Unpublished
data.
Positive-pressure ventilation during all phases of induction provides the largest
possible oxygen reserve during emergency airway management and will help mitigate
hypoxia resulting from prolonged efforts at intubation. The Sellick maneuver consists
of elevating the patient's chin (without displacing the cervical spine) and then
pushing the cricoid cartilage posteriorly to close the esophagus. A bimanual technique
was later described by Crowley and Giesecke[17]
in which the left hand is placed under the patient's neck to stabilize it. The cricoid
is stabilized between the thumb and third finger while the index finger pushes down.
