Pediatric Gastroesophageal Reflux 

Gastroesophageal reflux (GER) represents the most common gastroenterological disorder that leads to referral to a pediatric gastroenterologist during infancy. It refers to immaturity of lower esophageal sphincter (LES) function, manifested by frequent transient lower esophageal relaxations (tLESRs) that results in retrograde flow of gastric contents into the esophagus.

Although minor degrees of gastroesophageal reflux are noted in both children and adults, the degree and severity of reflux episodes are increased during infancy. Thus, gastroesophageal reflux represents a common physiological phenomenon in the first year of life. As many as 60-70% of infants experience emesis during at least one feeding per 24-hour period by age 3-4 months. The distinction between this "physiologic" gastroesophageal reflux and "pathologic" gastroesophageal reflux in infancy and childhood is determined, not merely by the number and severity of reflux episodes (when assessed by intraesophageal pH monitoring), but is most importantly determined by the presence of reflux-related complications, including failure to thrive, erosive esophagitis, esophageal stricture formation, and chronic respiratory disease.

Other complications noted in adults with gastroesophageal reflux, including Barrett esophagus and esophageal mucosal dysplasia, are uncommon in childhood.

Gastroesophageal reflux is classified as follows:

• Physiologic (or functional) gastroesophageal reflux: These patients have no underlying predisposing factors or conditions. Growth and development are normal, and pharmacologic treatment is typically not necessary.
• Pathologic gastroesophageal reflux or gastroesophageal reflux disease (GERD): Patients frequently experience complications noted above, requiring careful evaluation and treatment.^[1]
• Secondary gastroesophageal reflux: This refers to a case in which an underlying condition may predispose to gastroesophageal reflux. Examples include asthma (a condition which may also be, in part, caused by or exacerbated by reflux) and gastric outlet obstruction.

Similarities between adults and infants

• For many years, gastroesophageal reflux during infancy and childhood was thought to be a consequence of absent or diminished LES tone. However, studies have shown that baseline LES pressures are normal in pediatric patients, even in preterm infants.
• The major mechanism in infants and children has now been demonstrated to involve increases in tLESRs. Factors that may promote gastroesophageal reflux during tLESRs include increased intragastric liquid volume and supine and "slumped" seated positioning.
• Likely because of reduced viscosity and increased gastric volumes, the fluid diet of the infant facilitates the process of regurgitation compared with solid meals ingested by older children and adults.
• Esophageal clearance is similar in infants and adults, although evidence of reduced peristaltic activity in preterm infants has been reported.

Differences between adults and infants

• The volume ratio of meal-stomach-esophagus differs. Necessary amounts of infant caloric requirements easily overwhelm gastric capacity. Reflux occurs when esophageal capacity is exceeded by refluxate.
• Decreased gastric compliance is believed to lead to LES relaxation at lower intragastric volumes in infants. This aspect, in conjunction with abdominal wall muscle contraction (if it occurs during periods of LES relaxation) propels refluxate into the esophagus with subsequent regurgitation.
• An association between gastroesophageal reflux and delayed gastric emptying is recognized. This is more common in premature infants.

Gastroesophageal reflux and respiratory symptoms in infants and children

• Gastroesophageal reflux has been associated with significant respiratory symptoms in infants and children.
• The infant's proximal airway and esophagus are lined with receptors that are activated by water, acid, or distension. Activation of these receptors can increase airway resistance, leading to development of reactive airway disease.^[2]
• In 1892, Osler first postulated a relationship between asthma and gastroesophageal reflux, manifested by a bidirectional cause and effect presentation. Accordingly, although gastroesophageal reflux may be involved in both the etiology and progression of reactive airway disease, the asthmatic condition (in addition to antiasthmatic medications) may play a role in exacerbation of gastroesophageal reflux.
• One postulated mechanism for gastroesophageal reflux–mediated airway disease involves microaspiration of gastric contents that leads to inflammation and bronchospasm. However, experimental evidence also supports the involvement of esophageal acid–induced reflex bronchospasm, in the absence of frank aspiration. In such cases, gastroesophageal reflux therapy using either histamine 2 (H₂) blockers or proton pump inhibitors has been shown to benefit patients with steroid-dependent asthma, nocturnal cough and reflux symptoms.

Gastroesophageal reflux and other conditions in infants and children

• Two major areas of controversy surround the relationship between gastroesophageal reflux and both apnea and otolaryngologic disease. Although early studies appeared to demonstrate a link between gastroesophageal reflux and obstructive apnea (including an association with apparent life-threatening events [ALTE]), recent work suggests a weak relationship between these disorders.^[3]
• Laryngeal tissues are exquisitely sensitive to the noxious effect of acid, and recent studies support a significant relationship between laryngeal inflammatory disease (manifested by hoarseness, stridor, or both) and gastroesophageal reflux.
• Conversely, no conclusive clinical evidence supports a link between gastroesophageal reflux and other supraesophageal problems, including otalgia, recurrent otitis media, and chronic sinusitis.

Frequency

United States

• Symptoms of gastroesophageal reflux are most often directly related either to the consequences of emesis (eg, poor weight gain) or a result of exposure of the esophageal epithelium to gastric contents.
• Approximately 85% of infants vomit during the first week of life, and 60-70% manifest clinical gastroesophageal reflux at age 3-4 months.
• Symptoms abate without treatment in 60% of infants by age 6 months, when these infants begin to assume an upright position and eat solid foods. Resolution of symptoms occurs in approximately 90% of infants by age 8-10 months.
• Symptoms that persist after age 18 months suggest a higher likelihood of chronic gastroesophageal reflux.^[4]

Age

• Gastroesophageal reflux is most commonly seen in infancy, with a peak at age 1-4 months. However, it can be seen in children of all ages, even healthy teenagers.