Nausea and Vomiting

 

RESPONDING TO SYMPTOMS OF MINOR AILMENTS

2) NAUSEA & VOMITING

INTRODUCTION

·        Nausea and vomiting are common complaints, especially in:

• Gastrointestinal disorders
• Chronic diseases (e.g., cancer)

·        Nausea:

• Subjective, unpleasant sensation with an urge to vomit
• Associated with:
• Pallor
• Sweating
• Tachycardia
• Salivation
• Increased respiratory rate

·        Vomiting (Emesis):

• Reflex expulsion of stomach contents through the mouth

·        Retching:

• Involuntary, unsuccessful attempt to vomit

ETIOLOGY (CAUSES)

Common Causes

• Food allergies
• Gastrointestinal infections (e.g., food poisoning, viral gastroenteritis)
• Gastroesophageal reflux disease (GERD)
• Drugs (chemotherapy, radiation therapy)
• Migraine
• Pregnancy (morning sickness)
• Motion sickness
• Severe pain (e.g., kidney stones)
• Excess cannabis use

Serious Causes (Red Flags)

• Appendicitis
• Intestinal obstruction
• Tumors/cancer
• Poisoning or drug ingestion (especially in children)
• Peptic ulcers

CLINICAL PRESENTATION

• Dehydration
• Weight loss
• Mental confusion
• Reduced skin turgor
• Increased thirst
• Hypotension
• Muscle weakness
• Cardiac rhythm disturbances
• Metabolic alkalosis

PATHOPHYSIOLOGY

Phases of Emesis

1. Nausea – urge to vomit
2. Retching – muscular movements without expulsion
3. Vomiting – forceful expulsion of gastric contents

Mechanism

·        Controlled by the vomiting center in the brain

·        Inputs via:

• Vagus nerve
• Splanchnic nerves

·        Stimuli:

• Smell, sight
• Drugs, toxins
• Motion

·        Activation of Chemoreceptor Trigger Zone (CTZ) → initiates vomiting reflex

Key Neurotransmitters Involved

• Dopamine (D₂)
• Histamine (H₁)
• Serotonin (5-HT₃)
• Acetylcholine (Muscarinic)
• Substance P (NK₁ receptors)

PROCESS OF VOMITING

1. Deep inspiration
2. Contraction of abdominal muscles → ↑ intra-abdominal pressure
3. Closure of epiglottis (prevents aspiration)
4. Relaxation of esophagus & pyloric sphincter
5. Expulsion of gastric contents

MANAGEMENT

1) Non-Pharmacological Management

• Avoid triggering foods
• Eat small, frequent meals
• Maintain hydration
• Rest and fresh air
• Behavioral techniques (limited evidence)

2) Pharmacological Management

a) Antacids & Antisecretory Agents

• Neutralize gastric acid
• Example:
• Aluminum hydroxide
• Magnesium hydroxide

b) H₂-Receptor Antagonists

• Reduce acid secretion
• Examples:
• Cimetidine
• Famotidine
• Ranitidine
• Nizatidine

c) Proton Pump Inhibitors (PPIs)

• Strong acid suppression
• Examples:
• Omeprazole
• Esomeprazole
• Pantoprazole
• Rabeprazole
• Lansoprazole

d) Anticholinergics

• Block muscarinic receptors (vestibular system)
• Used in motion sickness
• Example:
• Scopolamine

e) Antihistamines (H₁ blockers)

• Useful in motion sickness, vertigo
• Side effects: sedation, blurred vision
• Examples:
• Diphenhydramine
• Meclizine

f) Dopamine Antagonists (D₂ blockers)

• Act on CTZ
• Side effects: sedation, hypotension, extrapyramidal symptoms
• Examples:
• Metoclopramide
• Domperidone
• Chlorpromazine
• Promethazine

g) Serotonin (5-HT₃) Antagonists

• Block serotonin receptors in CTZ & GI tract
• Used in chemotherapy-induced vomiting
• Example:
• Ondansetron

WHEN TO REFER TO DOCTOR

Immediate referral is needed if:

• Vomiting > 24 hours
• Blood in vomit
• Severe abdominal pain
• Severe headache or stiff neck
• Signs of dehydration:
• Dry mouth
• Reduced urination
• Dark urine
• Suspected poisoning