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Vomiting is the forceful retrograde
expulsion of gastric contents through the mouth consequent to the
coordinated contraction of diaphragm, abdominal, and respiratory
muscles. It is associated with a characteristic autonomic response,
including pallor, lethargy, hypersalivation, and tachycardia. This
differentiates vomiting from regurgitation,
which is an effortless involuntary
reflux of undigested gastric contents and is not associated with
abdominal/diaphragmatic contractions or autonomic responses. Nausea is the subjective unpleasant
sensation of impending vomiting that precedes but is not always associated
with vomiting. Emesis is a term that can be used to describe any
expulsion of gastric contents, and is useful to the physician when
describing symptoms that have not yet been fit into the more exact
categories of vomiting or regurgitation. Rumination is
voluntary reflux of gastric contents within the first hour after
eating and is associated with chewing and reswallowing of undigested
food. Retching or “dry heaves” is
the activated emetic reflux without vomiting, due to vomiting motion
against a closed glottis (Table 2–1). Vomiting should also
be differentiated from coughing or spitting of mucus from the lungs.
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Vomiting is a non-specific symptom caused by disorders affecting
a wide range of organs. It can represent a mild self-limited illness
(gastroenteritis), or occur as the result of severe life-threatening
conditions (midgut volvulus). Vomiting is a common complaint among
children who visit the pediatrician and the emergency department.
Primary etiologies originate from the gastrointestinal tract, and
are further divided into emergent disorders such as intussception
and non-emergent causes such as viral gastroenteritis. Secondary
causes involve etiologies that originate outside the gastrointestinal
tract (Figure 2–1). Many of the secondary causes
need immediate intervention, including cerebellar tumors, acute
hydronephrosis from uretero-pelvic junction (UPJ) obstruction, and
adrenal failure. In this chapter, we discuss a practical approach
to a child who presents with vomiting.
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Understanding the different neuroendocrine pathways and the neurotransmitters
that mediate vomiting is useful in understanding the treatment of
this symptom. Stimulation of the brain stem vomiting
center is the final common result of many possible initiating
events. The vomiting center is a ...