Nausea and Vomiting

Introduction

Nausea is usually defined as the inclination to vomit or as a feeling in the throat or epigastric region alerting an individual that vomiting is imminent. Vomiting is defined as the ejection or expulsion of gastric contents through the mouth, often requiring a forceful event.

• The three consecutive phases of emesis are nausea, retching, and vomiting. Nausea, the imminent need to vomit, is associated with gastric stasis. Retching is the labored movement of abdominal and thoracic muscles before vomiting. The final phase of emesis is vomiting, the forceful expulsion of gastric contents due to GI retroperistalsis.
• Vomiting is triggered by afferent impulses to the vomiting center, a nucleus of cells in the medulla. Impulses are received from sensory centers, such as the chemoreceptor trigger zone (CTZ), cerebral cortex, and visceral afferents from the pharynx and GI tract. When excited, afferent impulses are integrated by the vomiting center, resulting in efferent impulses to the salivation center, respiratory center, and the pharyngeal, gastrointestinal (GI), and abdominal muscles, leading to vomiting.

CLINICAL PRESENTATION

General: Depending on severity of symptoms, patients may present in mild to severe distress.

Symptoms: Simple: Self-limiting, resolves spontaneously and requires only symptomatic therapy Complex: Not relieved after administration of antiemetics; progressive deterioration of patient secondary to fluid–electrolyte imbalances; usually associated with noxious agents or psychogenic events Signs Simple: Patient complaint of queasiness or discomfort Complex: Weight loss, fever, and abdominal pain

Laboratory tests Simple: None Complex: Serum electrolyte concentrations; upper/lower GI evaluation. Other information: Fluid input and output Medication history Recent history of behavioral or visual changes, headache, pain, or stress Family history positive for psychogenic vomiting.

TREATMENT

• Goal of treatment: prevent or eliminate nausea and vomiting; ideally accomplished without adverse effects or with clinically acceptable adverse effects.

GENERAL APPROACH TO TREATMENT

• Treatment options for nausea and vomiting include drug and nondrug modalities and depend on associated medical conditions. For patients with simple complaints, perhaps related to food or beverage consumption, avoidance or moderation of dietary intake may be preferable. Patients with symptoms of systemic illness may improve dramatically as their underlying condition improves. Patients in whom these symptoms result from labyrinth changes produced by motion, may benefit quickly by assuming a stable physical position.
• Psychogenic vomiting may benefit from psychological interventions.

Pharmacotherapy:

Common antiemetics and adults’ dosage regimen

Antacids (various) 15–30 mL every 2–4 hours prn Liquid/oral.

Diphenhydramine (Gravinate) 25–50 mg every 4–6 hours prn Tab, cap, liquid

Hydroxyzine (Atarax) 25–100 mg every 4–6 hours IM

Tab Famotidine (Pepcid AC) 10 mg twice daily

Tab Maxolon (Metoclopramide) 10 mg four times daily

ANTIEMETIC USE DURING PREGNANCY

• Initial management of nausea and vomiting of pregnancy (NVP) often involves dietary changes and/or lifestyle modifications.
• Pyridoxine (10–25 mg one to four times daily) is recommended as first-line therapy with or without doxylamine (12.5–20 mg one to four times daily). Patients with persistent NVP or who show signs of dehydration should receive IV fluid replacement with thiamine. Ondansetron 2 to 8 mg orally/IV every 8 hours as needed may alleviate NVP.