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Gastroesophageal reflux

Gastroesophageal reflux (GER) is near-universal in infants, decreasing in frequency with growth and maturation. While it lies on a continuum with vomiting, it lacks the element of gastric contraction and forceful expulsion implied with vomiting. It still occurs in normal children as well. Reflux becomes pathologic gastroesophageal reflux disease (GERD) when associated with: Pain Respiratory symptoms Failure to thrive Dysphagia GERD in childhood is a risk factor for GERD in adulthood 1 so early diagnosis and control are essential. Pathophysiology Reflux is usually prevented by six interacting mechanisms. Breakdown of any of these mechanisms increases the chance of reflux. Four are at the distal esophagus: Intact lower esophageal peristalsis Competent lower esophageal sphincter (LES) The reinforcing action of the diaphragm hiatus The entry of the esophagus into the gastric cardia at an acute angle (Angle of His) The other two have to do with the stomach: Active gastric peristalsis Relaxed pylorus to promote gastric emptying Etiology Transient lower esophageal sphincter relaxation (TLESR) has been implicated in allowing reflux episodes to occur however many factors contribute to the transition of reflux from a benign to a malignant classification 2. One such factor is decreased esophageal clearance, from supine positioning or infrequent swallowing (frequently seen with neurological disorders) or dysmotility, a complication seen in patients with repaired esophageal atresia (EA) and tracheoesophageal fistula (TEF) 3. Chitkara and colleagues 4 have recently shown that children with GERD, with or without esophagitis, have decreased number and abnormal pattern of esophageal body contractions. The presence of a nasogastric feeding tube can also impede acid clearance, though the number of reflux episodes is unchanged; however, a large tube can convert a non-refluxer to a refluxer5. Straining, a favorite maneuver to provoke reflux in adults during a fluoroscopic examination, does not do the same in children, unless it happens to coincide with a TLESR 6. High gastric volume (due to large feeds or delayed gastric emptying) and increased osmolality in gastric contents are associated with more and longer periods of lowered LES pressure 7. However, delayed emptying time in another study did not correlate with severity of reflux 8. Similarly, while case studies and anecdotal evidence suggest an association of reflux with dental erosions, laryngeal disorders, sinusitis, and otitis media, convincing data are lacking to prove causality 9. Hiatal hernia promotes reflux because of the loss of diaphragmatic hiatal support for the LES and the opening of the angle of His. Clinical: An important morbidity associated with GER is aspiration. The effects of gastric acid on the tracheobronchial tree visible on plain film may be subtle hyperinflation due to vagus-mediated bronchospasm or flagrant peribronchial inflammation, atelectasis, or pneumonia. In the child who is usually in a supine position, the upper lobes, particularly on the right, may be more involved; a child who is more erect will deposit the aspirate into the lower lobes. Again, however, when the association of GER (or esophagitis) and aspiration (as diagnosed by bronchoalveolar lavage) is examined closely, several studies have failed to show more than passing statistical relevance 10. Even aspiration of saliva, if it occurs chronically, is far from benign. Distinguishing between salivary and gastric aspiration can be important for therapy and in cases where GER studies fail to show expected reflux, nuclear medicine salivagram can be useful 11. Diagnosis: Since GER is notoriously spontaneous and irregular, 24-hour esophageal pH monitoring has long been regarded as the "gold standard" for detecting reflux. Labeling infant formula with a short-lived radioisotope like Tc99m similarly allows a longer imaging window to detect infrequent reflux episodes. Imaging over the lung fields can also detect subclinical aspiration 12. However, the immobilization or sedation that successful imaging requires makes impractical in many departments 13. PH probe recording has also been instrumental in determining that children with severe GER actually hypersecrete gastric acid 13. But several recent studies have highlighted the difficulty of making the transition from "association" to cause. Mattioli and colleagues 15 found equally abnormal studies in asthmatic and non-asthmatic patients. Indeed, when a 1992 study paired pH probe readings and a nuclear gastric scan, pH drops in the esophagus occurred at different times than the waves of reflux registered on the scan 16. Ultrasound may detect gastroesophageal reflux. This is most commonly detected in a vomiting infant who undergoes ultrasound of the stomach for hypertrophic pyloric stenosis. Complications: The mucosal irregularity, ulceration, and narrowing of reflux esophagitis can be readily seen on barium UGI. There are several recognized complications. Scarring and stricture may bring the unrecognized esophagitis to clinical attention when food impaction ensues. Barrett esophagus, where a specialized epithelium known to be preneoplastic is found in an esophageal segment of variable length, is found particularly in patients predisposed to severe GER: those with severe neurologic impairment who are mainly recumbent, those with chronic lung disease such as cystic fibrosis who cough and have pulmonary toilet in the head-down position, those with primary esophageal dysmotility or hiatal hernia 17. Schatzki rings, less familiar in children than in adults, are found in a similar group of patients 18. PH probe studies can help distinguish a subset of patients with severe esophagitis but little or no reflux: those with eosinophilic esophagitis. Food allergy is suspected in many cases, especially since it is often concurrent with other allergic symptoms, but difficult to prove. Treatment: Thickened feeds, postural changes, prokinetic drugs and acid-reducing drugs are all in the pediatrician's armamentarium against GERD. Nissen fundoplication is the surgical procedure of choice to control GER. It has its own complications, however, which can adversely affect the patient's ability to eat 20. Tightening the gastroesophageal junction is a delicate balance between tight enough to prevent reflux but loose enough to permit bolus passage. Patients who have had repair of esophageal atresia/tracheoesophageal fistula already suffer from dysmotility of the esophagus below the anastomosis. This promotes reflux and usually is the reason for the Nissen. However, the ability to propel the bolus into the stomach may then be completely compromised. Fundoplication can completely break down, but more often a large paraesophageal hernia forms that extends into the chest through the loosened hiatus, growing larger with the drops in intrathoracic pressure that accompany normal respiration, or with retching. This can compress the distal esophagus still further and impede bolus passage. Alternatively, the wrap may remain intact but herniate through the diaphragmatic hiatus into the chest. The loss of hiatal support may diminish the wrap's effectiveness. All of these complications mean that GER has a good chance of continuing or recurring despite surgery-up to 2/3 of the time, as shown in one study 21. UGI and barium swallow techniques: Because most cases of uncomplicated reflux are diagnosed clinically and treated without having an imaging study, the patient that comes to the radiology suite is already part of a select population with a higher probability of having something wrong. Good examination technique will maximize the chance of seeing the pathology. The barium swallow is not a sensitive test for reflux because of the time required to detect significantly frequent episodes. Despite this, if the radiologist wishes to elicit reflux, he/she must exercise patience. It is best to do this at the end of the examination. The child's stomach should be full and he should be relaxed and distracted. If the preceding part of the study has been unpleasant, the infant might be allowed to feed in the parent's arms until full, then replaced beneath the fluoroscope. Darkening the room and minimizing noise might encourage the child to fall asleep in a supine position. Videotapes provide solace and distraction for the toddler. Position the fluoroscope to show the esophagus, then image only for about 1 second out of every 7-10, for a total of 5 minutes (less than 1 minute of fluoroscopy time). Significant reflux, i.e. reaching the clavicles, cervical esophagus or pharynx, will persist long enough to be recorded. How long it takes the refluxed material to clear is also an important observation. Crying reinforces the diaphragmatic hiatus and minimizes reflux, so assessment in an inconsolable infant may have to be abandoned. For older children and teenagers, more adult maneuvers can work to uncover reflux: deep breaths with forceful exhalation ("like blowing out birthday candles"), lifting the legs to a 45 degree angle and holding them, rolling from side to side, and coughing. The water-siphon test (giving water to drink after the stomach is filled with barium) has its proponents and detractors, but most agree that if no backwash of barium into the esophagus is elicited, the patient is very unlikely to have GER. UGI and Barium Swallow Technique after Fundoplication A large proportion of patients coming for evaluation of reflux or vomiting are those who have had a Nissen fundoplication. From the surgeon's perspective, the most important question to answer is whether the Nissen is intact. The contrast study should try to duplicate the patient's feeding situation as much as possible to find the source of the symptoms: oral feeding vs. tube feeding, how much is given and at what rate, what position the child is usually in when the symptoms happen. Possible pathology in this population might include: Wrap is too tight Wrap is too loose Paraesophageal herniation of the fundic fold while the gastroesophageal junction remains below the diaphragm Wrap herniation through the diaphragmatic hiatus Complete breakdown of the wrap Generally, a small paraesophageal hernia will not prompt surgical action. A Nissen that is too tight might be dilated with a balloon or a bougie. But if there is a hiatal hernia or an extremely large paraesophageal hernia that compresses the distal esophagus, or if there is no discernible fundic defect at all, the surgeons will be more likely to re-operate. The study should start with injection of the gastrostomy tube, if the patient has one, with an amount of fluid appropriate to the patient's feeding schedule. The patient should be in his usual position of feeding; for many neurologically impaired patients, this is supine. The fluoroscopic checklist includes: Position of the gastrostomy balloon (does it block the gastric outlet?) Does the child empty his stomach in this position, or must he be turned or his head elevated? Is there active gastric peristalsis, or is the stomach paretic and full of fluid? What happens when the stomach is filled with contrast? Is there expansion of the fundic wrap above the diaphragm? If there is reflux, how high does it go, and how long does it take to clear? If no reflux occurs, a few cc's of barium should be given by mouth, even if the patient is not usually fed by mouth; he should get still more by this method if he is on oral feeds. The checklist for this "esophagram" portion of the study includes: Is there good esophageal peristalsis? Is there fast passage through the wrapped gastroesophageal junction, or is the distal esophagus fluid-filled and obstructed? Is the gastroesophageal junction above or below the diaphragm?