What is the approach to managing emesis (vomiting)?

From the Guidelines

The approach to vomiting involves first identifying and treating the underlying cause while providing supportive care, with a multimodal approach to prophylaxis considered in all patients, incorporating first-line antiemetics such as ondansetron, promethazine, or metoclopramide, as recommended by recent guidelines 1. When managing vomiting, it is essential to begin with a thorough assessment of the patient's history, including onset, frequency, and associated symptoms.

• For mild to moderate vomiting in adults, antiemetics like ondansetron (4-8mg orally or IV every 8 hours), promethazine (12.5-25mg orally, IV, or rectally every 6 hours), or metoclopramide (10mg orally or IV every 6 hours) can be effective, as supported by studies 1.
• Maintain hydration with small sips of clear fluids or ice chips, gradually advancing to the BRAT diet (bananas, rice, applesauce, toast) as tolerated.
• Severe or persistent vomiting may require IV fluids to correct electrolyte imbalances and prevent dehydration.
• For specific causes, targeted treatments are necessary: antivirals for viral gastroenteritis, antibiotics for bacterial infections, or discontinuation of offending medications.
• In pregnancy, pyridoxine (vitamin B6) 25mg three times daily, with or without doxylamine 12.5mg, is first-line therapy, as recommended by guidelines 1.
• Children require weight-based dosing of medications and careful monitoring for dehydration.
• Red flags warranting immediate medical attention include hematemesis, severe abdominal pain, projectile vomiting, altered mental status, or signs of dehydration. The use of a multimodal approach to prophylaxis, incorporating first-line antiemetics, can help reduce the incidence of vomiting, as shown in recent studies 1.
• A multimodal approach to PONV prophylaxis should be considered in all patients and incorporated into ERAS protocols, with patients with 1–2 risk factors receiving a two-drug combination prophylaxis using first-line antiemetics, and patients with ≥ 2 risk factors undergoing colorectal surgery receiving 2–3 antiemetics 1.
• If nausea and or vomiting still occur, despite prophylaxis, salvage therapy should be provided using a multimodal approach using different classes of drugs from those used for prophylaxis. Vomiting is a protective reflex triggered by stimulation of the chemoreceptor trigger zone or vomiting center in the brain, which explains why medications targeting these pathways effectively reduce symptoms, as discussed in the literature 1.

From the FDA Drug Label

For the Prevention of Nausea and Vomiting Associated with Emetogenic Cancer Chemotherapy Intravenous infusions should be made slowly over a period of not less than 15 minutes, 30 minutes before beginning cancer chemotherapy and repeated every 2 hours for two doses, then every 3 hours for three doses The initial two doses should be 2 mg/kg if highly emetogenic drugs such as cisplatin or dacarbazine are used alone or in combination. For less emetogenic regimens, 1 mg/kg per dose may be adequate.

The approach to vomiting involves administering metoclopramide at a dose of 2 mg/kg for highly emetogenic chemotherapy and 1 mg/kg for less emetogenic regimens, given 30 minutes before chemotherapy and repeated at specific intervals 2.

For the Prevention of Postoperative Nausea and Vomiting Metoclopramide Injection, USP should be given intramuscularly near the end of surgery. The usual adult dose is 10 mg; however, doses of 20 mg may be used

Alternatively, metoclopramide can be administered intramuscularly at a dose of 10 mg near the end of surgery to prevent postoperative nausea and vomiting 2.

1. 2 Prevention of Postoperative Nausea and/or Vomiting Adults Adult surgical patients who received ondansetron immediately before the induction of general balanced anesthesia... were evaluated in two double-blind US trials involving 554 patients. Ondansetron Injection (4 mg) intravenous given over 2 to 5 minutes was significantly more effective than placebo.

Ondansetron can also be used to prevent postoperative nausea and vomiting, administered intravenously at a dose of 4 mg immediately before induction of anesthesia 3.

1. 3 Prevention of Further Postoperative Nausea and Vomiting Adults Adult surgical patients receiving general balanced anesthesia... who received no prophylactic antiemetics and who experienced nausea and/or vomiting within 2 hours postoperatively were evaluated in two double-blind US trials involving 441 patients. Patients who experienced an episode of postoperative nausea and/or vomiting were given Ondansetron Injection (4 mg) intravenously over 2 to 5 minutes, and this was significantly more effective than placebo.

If nausea and vomiting occur postoperatively, ondansetron can be administered intravenously at a dose of 4 mg to prevent further episodes 3.

From the Research

Approach to Vomiting

• Vomiting can be a symptom of various conditions, ranging from mild to life-threatening, and its management depends on the underlying cause 4, 5, 6, 7, 8.
• The evaluation of vomiting involves assessing the patient's airway, breathing, and circulation, as well as their hydration status and red flag signs, such as bilious or bloody vomiting, altered sensorium, or severe dehydration 5, 6.
• A careful history and physical examination are essential to guide the initial evaluation and narrow the differential diagnosis, including associated symptoms, timing of onset and duration of symptoms, exacerbating or relieving factors, alarm symptoms, medication and substance use, and comorbidities 4, 6, 7.

Acute vs. Chronic Vomiting

• Acute vomiting typically lasts up to 7 days and is often treated symptomatically, while chronic vomiting lasts 4 weeks or longer and has a broader differential diagnosis, including gastrointestinal, infectious, metabolic, neurologic, psychiatric, or medication-related causes 4, 7.
• The management of acute vomiting may involve antiemetic medications, fluid and electrolyte replacement, and small, frequent meals, while chronic vomiting often requires a more comprehensive approach, including investigations to diagnose underlying causes and targeted treatment 4, 5, 6, 7, 8.

Treatment Options

• Antiemetic medications, such as serotonin antagonists or dopamine antagonists, can be effective in reducing symptoms of acute nausea and vomiting, but chronic symptoms may require more targeted therapy, including medications that address the suspected cause of symptoms and the neurotransmitters involved in central and peripheral pathways of nausea and vomiting 4, 6, 8.
• Nonpharmacologic management options, such as fluid and electrolyte replacement, small, frequent meals, and avoidance of trigger foods, can also be beneficial in managing vomiting symptoms 4, 5, 6.
• Emerging therapies, including bioelectrical neuromodulation, behavioral and surgical therapies, and complementary medicine, may offer new treatment options for patients with refractory nausea and vomiting 8.