Gastroparesis

GENERAL PRINCIPLES

Definition

Gastroparesis consists of abnormally delayed emptying of stomach contents into the small bowel in the absence of gastric outlet obstruction or ulceration, usually as a result of damage to the nerves or smooth muscle involved in gastric emptying.

Etiology

• Mechanical obstruction should always be excluded.

• In addition to evaluating for acute metabolic derangements and potential offending medications (e.g., narcotics, anticholinergic agents, chemotherapeutic agents, glucagon-like peptide 1 receptor agonists, and amylin analogs), patients with gastroparesis should be screened for diabetes mellitus, thyroid dysfunction, neurologic disease, prior gastric or bariatric surgery, and autoimmune disorders (e.g., scleroderma).

• If no predisposing cause is identified, gastroparesis is designated idiopathic.

DIAGNOSIS

Clinical Presentation

Symptoms include nausea, bloating, and vomiting, usually hours after a meal.

Diagnostic Testing

A 4-hour gastric-emptying study (gamma camera scan after a radiolabeled meal) can quantify gastric emptying; medications that can delay gastric emptying (i.e., opioids and anticholinergics) should be stopped at least 48 hours prior to testing.¹⁰⁴ However, the finding of gastric emptying delay may not be consistent on repeat study.

TREATMENT

• First steps in management include fluid restoration, correction of electrolytes, nutritional support, and optimization of glucose control for diabetic patients. Indications for postpyloric enteral feeding include unintentional loss of gt;10% of usual body weight and/or refractory symptoms requiring repeated hospitalizations.

• Nutritional consultation can help address nutritional deficiencies and optimize diet, especially to decrease dietary fat and insoluble fiber.

Medications

• Metoclopramide (10 mg PO qid half an hour before meals) often represents the first line of prokinetic therapy but has variable efficacy, and side effects (drowsiness, tardive dyskinesia, parkinsonism) may limit chronic use as some are permanent.

• Erythromycin (125-250 mg PO tid or 200 mg IV) can improve gastric emptying in the short term, but tachyphylaxis is a significant limitation precluding chronic benefit.

• Domperidone (20 mg PO qid before meals and at bedtime) does not cross the blood-brain barrier, but hyperprolactinemia can result. ECGs should be checked at baseline and on follow-up given the risk of QT prolongation. Domperidone is not available in the United States.

• Antiemetics may improve associated nausea and vomiting but will not improve gastric emptying.

Surgical Management

• Enteral feeding through a jejunostomy feeding tube may be required for supplemental nutrition and is favored over TPN.

• Gastric electrical stimulation using a surgically implanted stimulator (Enterra) may reduce symptoms of nausea and vomiting in half of medically refractory patients, but gastric emptying is typically not enhanced by this approach.¹⁰⁶