Vomiting (Emesis) – The Body’s Defense Mechanism

Overview

• Vomiting is an involuntary reflex (emetic reflex) designed to protect the body.
• Purpose: Rapidly remove irritants, toxins, or pathogens from the gastrointestinal (GI) tract.

Causes of Vomiting

• Consumption of bad food or infected food.
• Ingestion of poisons or toxins.
• Gastrointestinal infections.
• Medications or drugs.
• Physical stimuli like distention or irritation of the stomach.
• Sensory triggers:
  • Bad smells.
  • Pain.
  • Visual stimuli.
• Inner ear (vestibular apparatus) triggers (motion sickness).
• Increased intracranial pressure (ICP) causes early, forceful vomiting.

Neural Control

• The medulla oblongata, specifically the emetic center, orchestrates vomiting.
• Chemoreceptors detect irritants/signals and activate this center.

The Vomiting Reflex

• Involves coordination of smooth muscle in the stomach and intestines.
• Results in forceful expulsion of stomach contents.
• Contents may include bile and intestinal contents if severe.

Complications of Prolonged Vomiting

• Dehydration:
  • Loss of fluids leads to hypovolemia.
  • Results in low blood pressure, paleness, weakness.
• Electrolyte imbalances:
  • Loss of hydrogen ions (acidic gastric fluid) can make bodily fluids more basic.
  • Loss of sodium, potassium, and chloride.
• Nutritional deficiencies leading to malnourishment.
• Salivation increases reflexively to protect oral tissues.

Physiological Signs of Stress

• SNS activation:
  • Vasoconstriction (pale skin).
  • Sweating.
  • Tachycardia (fast heart rate).
  • Feeling distressed and anxious.

Causes and Triggers

• Overeating or food intolerances.
• Infections or inflammation.
• Psychological triggers (e.g., nausea from distress).
• Motion sickness:
  • Inner ear sensors detect movement, conflicting visual input causes nausea.
• Increased intracranial pressure (ICP):
  • Causes early, forceful projectile vomiting.
• Pregnancy:
  • Hormonal changes may trigger morning sickness.
• Poisoning or toxins.
• Blood in vomit (hematemesis):
  • Bright red indicates recent bleeding.
  • Coffee-ground appearance suggests older blood digestion.
• Obstructions or infection may cause recurrent vomiting.

Signs of Serious Conditions

• Blood in vomit:
  • Hematemesis (fresh blood).
  • Coffee ground vomitus.
• Green or yellow tinge:
  • Indicative of bile, possibly from lower GI or intestinal obstruction.
• Unconsciousness:
  • Possible spinal injury.
  • Immediate stabilization and hospital care needed.

Emergency Response

• Protect the airway, especially if unconscious.
• Spinal precautions if trauma suspected.
• Transport to hospital immediately.
• Ensure airway and breathing are secure.

Summary

• Vomiting is a protective reflex but can cause serious electrolyte imbalance, dehydration, and injury.
• Recognizing causes and signs of dangerous vomiting is essential for prompt medical intervention.