The forceful expulsion of gastric contents through the mouth is defined as vomiting. Vomiting can be caused by a benign, self-limited process or it may be indicative of a serious underlying disorder.
1.Pathophysiology of vomiting
Vomiting is usually preceded by nausea, increased salivation, and retching. It is distinct from regurgitation, which is characterized by passive movement of gastric contents into the esophagus.
Prolonged vomiting results from intense gastric peristaltic waves, usually secondary to gastric outlet obstruction caused by hypertrophic pyloric stenosis or pylorospasm.
Retching often precedes vomiting and is characterized by spasmodic contraction of the expiratory muscles with simultaneous abdominal contraction.
B. Clinical evaluation of vomiting in infancy
One of the major consideration in infants is pyloric stenosis. Hypertrophy of the pylorus causes gastric outlet obstruction at the pyloric canal. Five percent of infants whose parents had pyloric stenosis develop this disorder. Males are affected more often than females.
Symptoms of pyloric stenosis usually begin at age 2 to 3 weeks, but may occur at birth or present as late as 5 months.
Retrograde movement of gastric contents into the esophagus is defined as the Gastroesophageal reflux (GER). GER occurs in 65% of infants and is caused by inappropriate relaxation of the lower esophageal sphincter.
GER is considered pathologic if symptoms persist beyond 18 to 24 months and/or if significant complications develop, such as failure to thrive,recurrent episodes of bronchospasm and pneumonia, apnea, or reflux esophagitis.
Gastrointestinal allergy : Cow milk allergy is rare in infancy and early childhood and generally resolves by 2 to 3 years of age. Vomiting, diarrhea, colic and gastrointestinal loss of blood may occur.
2. Clinical evaluation of vomiting in childhood
Peptic ulcer in early childhood is often associated with vomiting. Peptic ulcer disease should be suspected if there is a family history of ulcer disease, or if there is hematemesis or unexplained iron deficiency anemia. Abdominal pain typically wakes the patient from sleep.
Pancreatitis is a relatively rare cause of vomiting. Patients usually complain of epigastric pain, which may radiate to the mid-back.
Other factors predisposing to pancreatitis include viral illnesses (mumps), drugs (steroids, azathioprine), congenital anomalies of the biliary or pancreatic ducts, cholelithiasis, hypertriglyceridemia, and a family history of pancreatitis.
Persistent vomiting without other gastrointestinal or systemic complaints suggests an intracranial tumor or increased intracranial pressure. A detailed neurologic examination should be performed.
3. Physical examination of the child with persistent vomiting
Volume depletion often results from vomiting, manifesting as sunken fontanelles, decreased skin turgor, dry mouth, absence of tears, and decreased urine output.
Peritoneal irritation should be suspected when the child keeps his knees drawn up or bends over. Abdominal distension, visible peristalsis, and increased bowel sounds suggests intestinal obstruction.
Abnormal masses, enlarged organs, guarding or tenderness should be sought.
Intussusception is often associated with a tender, sausage-shaped mass in the right upper quadrant and an empty right lower quadrant (Dance sign).
Digital rectal exam should also be done. Decreased anal sphincter tone and large amounts of hard fecal material in the ampulla suggests fecal impaction.Constipation, increased rectal sphincter tone, and an empty rectal ampulla suggests Hirschsprung disease.
4. Laboratory evaluation
Serum electrolytes should be obtained when dehydration is suspected.
Urinalysis may detect a urinary tract infection or suggest the presence of a metabolic disorder.
Plasma amino acids and urine organic acids should be measured if metabolic disease is suspected because of recurrent, unexplained episodes of metabolic acidosis.
Serum ammonia should be obtained in cases of cyclic vomiting to exclude a urea cycle defect.
Liver chemistries and serum ammonia and glucoselevels should be obtained if liver disease is suspected.
Serum amylase is frequently elevated in patients who have acute pancreatitis. Serum lipase levels may be more helpful because it remains elevated for a number of days following an acute episode.
Initial therapy should correct hypovolemia and electrolyte abnormalities. In acute diarrheal illnesses with vomiting, oral rehydration therapy is usually adequate for treatment of dehydration.
Bilious vomiting and suspected intestinal obstruction is managing by giving nothing by mouth, and by placing a nasogastric tube connected to intermittent suction. Bilious vomitingrequires surgical consultation.
Antiemetic agents usually are not required because most instances of acute vomiting are caused byself-limited,infectiousgastrointestinal illnesses. Antiemetic drugs may be indicated for postoperative emesis, motion sickness, cytotoxic drug-evoked emesis, and gastroesophageal reflux disease.
Diphenhydramine and dimenhydrinate are useful in treating the symptoms of motion sickness or vestibulitis.
Prochlorperazine and chlorpromazine have anticholinergic and antihistaminic properties and are used to treat vomiting caused by drugs, radiation, and gastroenteritis.