Nausea and Vomiting - Comprehensive Notes

Nausea and Vomiting

Learning Objectives

• Define nausea, retching, vomiting, regurgitation, and rumination.
• Identify the physiologic mechanisms underlying nausea and vomiting.
• Differentiate between items on the age-appropriate differential diagnosis for patients presenting with vomiting.

Definitions

• Nausea:
  • Unpleasant, painless, subjective feeling that one will imminently vomit.
  • Often vague and epigastric/abdominal, but not always.
  • Associated with autonomic changes:
    • Salivation
    • Cold sweating
    • Peripheral vasoconstriction
    • Proximal gastric relaxation
    • Retrograde movement of intestinal contents
    • Changes in respiratory rhythm and quality
    • Mydriasis
• Retching:
  • Strong, involuntary reverse movements (retroperistalsis) of the stomach and esophagus without vomiting.
  • Accompanied by spasmodic contractions of the diaphragm and abdominal wall, closing of the glottis, and relaxation of the lower esophageal sphincter.
  • Gastric material may be moved into the esophagus in preparation for vomiting.
• Vomiting:
  • Retrograde ejection of gastrointestinal (or esophageal) contents from the mouth.
  • Forceful (unable to keep contents in the mouth) and involuntary.
  • Associated with relaxation of the diaphragm and upper esophageal sphincter and reversal of intrathoracic pressure from negative to positive.
• Regurgitation:
  • The spitting up of food from the esophagus or stomach, typically without nausea or forceful contractions of the abdominal muscles.
  • Apparently effortless and typically caused by lower esophageal sphincter dysfunction.
  • High tone of the lower esophageal sphincter may lead to simple esophageal emptying (think achalasia).
  • Low tone of the lower esophageal sphincter may lead to reflux when the gastric musculature contracts.
• Rumination:
  • Regurgitating undigested or partially digested food from the stomach, rechewing it, and then either re-swallowing it or spitting it out.
  • Again effortless.
  • Psychological or behavioral problems are considered the cause, although considered behavioral or involuntary.
  • Often occurs in association with dyspepsia and digestive problems.

Mechanisms of Nausea and Vomiting

Pathways

• Higher Centers (Cortex):
  • Sights, smells, memory, anticipation, fear, pain.
• CTZ (Chemoreceptor Trigger Zone):
  • 4th ventricle, adjacent brainstem.
  • Electrolytes, hormones, opioids, chemotherapy, anesthetics.
• VC (Vomiting Center):
  • Medulla, brainstem.
• Vagus Nerve:
  • Stomach, small intestine.
• Vestibular Apparatus:
  • Cerebellum.
  • Chemotherapy, surgery, motion sickness, radiotherapy.

Stimuli

1. GI System or Peripheral Stimulation:
   • Typically with stimulation of enterochromaffin cells.
   • Afferents mediated primarily by the vagal nerve.
   • Primary stimuli include:
     • Stretching (gastric stasis or dysmotility of the small intestine or other organ - less so large intestine, hollow organ obstruction like in appendicitis or cholelithiasis or nephrolithiasis, tumor, constipation, filling with air like in lactose intolerance).
     • Capsular distension of a solid organ (think liver/pancreas).
     • Compression (from surrounding organs/tumor/ascites, etc.).
     • Tissue injury (ischemia incl bowel/heart/other, inflammation, chemotherapy, radiation, surgery).
2. Cortical/Limbic System:
   • Hypothalamus, amygdala, thalamus, hippocampus.
   • Increased ICP, vascular (migraine, hyper/hypotension), emotional (fear, memory, pain, smell, sight, anticipation).
3. Vestibular Stimulation:
   • Disease of the labyrinth which may contradict signals of visual and proprioceptive information.
4. Chemoreceptor Trigger Zone in Medulla:
   • Drugs (chemo, opioids, some abx, anesthetics, ipecac).
   • Hormones (esp sex hormones during menses or pregnancy).
   • Metabolic disturbances (electrolyte imbalances incl hyperCa, hyperammonemia, uremia, acidosis).
   • Toxins (ex: from bacteria causing food poisoning).
   • Sometimes direct effects of increased ICP.
5. Other Stimuli:
   • Glossopharyngeal/trigeminal afferents (think gag, irritation w/ sinusitis secretions, etc.)

Receptor Involvement

• Vestibular System:
  • Receptors: H1, ACh
  • Stimuli: Motion, opioids, base of skull tumors
  • Antiemetics: Cyclizine
• Chemoreceptor Trigger Zone:
  • Receptors: D2, 5HT3, NK1
  • Stimuli: Drugs, metabolic, toxins
  • Antiemetics: Haloperidol, metoclopramide, setrons (aprepitant)
• Gastrointestinal Tract:
  • Receptors: 5HT4 (prokinetic), 5HT3 on vagal nerve endings, ACh
  • Stimuli: Gastric stasis, Visceral/serosal
  • Antiemetics: Domperidone, metoclopramide (prokinetic), Cyclizine (to slow transit)
• Cerebral Cortex:
  • Receptors: GABA, H1
  • Stimuli: Pain, fear, anxiety, Raised ICP
  • Antiemetics: Cyclizine
• Vomiting Center:
  • Receptors: H1, ACh, 5HT, NK1, mu
  • Stimuli: Raised ICP, Meningeal infiltration
  • Antiemetics: Cyclizine, Levomepromazine (aprepitant)

Clinical Cases

Case 1: Neonate

• History:
  • 48-hour old ex-FT male born at home to a 28-year-old G1P1 mother with no reported complications of pregnancy or delivery presents with vomiting.
  • Baby is breastfeeding exclusively and seems to be swallowing appropriately without coughing/choking.
  • Vomitus is bilious and occurs 20 minutes after a feed.
  • The baby had meconium-stained amniotic fluid but hasn’t stooled since birth.
  • Afebrile but ill-appearing with poor tone, color, and alertness.
• Differential Diagnosis:
  • Reflux +/- overfeeding if bottle/cup feeding.
  • Swallowed amniotic fluid which may cause irritation/discomfort.
  • Swallowed maternal blood which may cause irritation (swallowed maternal blood during delivery in first 2 days or mother has cracked nipples).
  • Obstruction (malrotation, esophageal/intestinal atresia, meconium ileus or plug, Hirschsprung, etc.).
  • Necrotizing enterocolitis (10% occur in full-term babies).
  • Inborn error of metabolism.
  • Sepsis/meningitis/UTI.
  • Non-accidental trauma.
• Resolution:
  • Malrotation is confirmed on imaging, and the pediatric surgeon removes 10 cm of necrotic bowel. The patient tolerates the procedure well and is able to leave with the mother after his hospital course.

Selected Considerations: Esophageal Atresia

• Prenatal history of polyhydramnios and intolerance of initial feeding.
• Accompanied distal tracheoesophageal fistula in 85% of cases.
• Associated with other anomalies in 15-50% of patients (especially VACTERL).
• Diagnosis: plain films after passage of an opaque rubber catheter, which coils in the upper pouch.

Selected Considerations: Pyloric Stenosis

• Non-bilious projectile vomiting.
• Beginning at 2-3 weeks of age and increasing during the next month.
• Often in a firstborn male child.
• Propulsive gastric waves can be seen on the abdominal wall, and a palpable “olive” in the epigastrium (felt best during or after feeding) represents the hypertrophied pyloric muscle.
• Clinically: Dehydration, poor weight gain, hypochloremic metabolic alkalosis.
• Contrast study: “string sign” and ultrasound with hypertrophied tissue.
• Treatment: Surgical pyloromyotomy.

Selected Considerations: Duodenal Atresia

• Bilious vomiting.
• Radiographic “double-bubble” sign.
• Associated prematurity (and polyhydramnios).
• Anomalies, including renal, cardiac, and vertebral defects, occur in approximately 75% of infants.
• Trisomy 21 is seen in about 50%.

Case 2: Toddler

• History:
  • 3-year-old female presents with vomiting.
  • She had a recent diarrheal illness but started to get better.
  • She has now had three episodes of bilious vomiting and anorexia.
  • She now has periods of sudden onset and offset abdominal pain where she screams and draws her legs to her chest.
  • After these periods, she appears lethargic.
• Differential Diagnosis:
  • Food issues (anaphylaxis, food poisoning, protein intolerance).
  • Gastritis/gastroparesis (non-infectious) or PUD.
  • Infection (gastroenteritis, cholecystitis, appendicitis, UTI, PNA, flu/covid, pharyngitis, hepatitis, malaria, AOM).
  • Renal causes (renal tubular acidosis, renal failure, UPJ obstruction).
  • Malrotation w/ volvulus, intussusception, ileus/obstruction.
  • Pancreatitis.
  • Torsion (ovarian or testicular).
  • Adrenal insufficiency.
  • Electrolyte derangement/acidosis.
  • Constipation.
  • Trauma: head injury, NAT, abdominal trauma w/ duodenal hematoma.
  • Incr. intracranial pressure or intracranial lesion.
• Resolution:
  • Intussusception is confirmed on imaging, and the pediatric surgeon reduces the telescoped bowel. The patient tolerates the procedure well and is able to leave with the mother after his hospital course without recurrence of the intussusception.

Selected Considerations: Peptic Ulcer Disease

• Causes:
  • H. pylori infections, reflux gastritis, nonsteroidal anti-inflammatory agents, and rare gastrin-secreting tumors (Zollinger-Ellison syndrome).
  • Stress ulcers in sepsis, burns, surgery, head trauma, and severe acute illness.
• Diagnosis:
  • History mostly with empiric treatment.
  • Endoscopy (evaluation for H. pylori).
• Treatment:
  • Acid suppression.
  • Treat H. pylori: double or triple antibiotics PLUS acid suppression drugs.

Selected Considerations: Appendicitis

• Periumbilical pain is followed by vomiting and anorexia.
• Commonly see fever, leukocytosis with left shift, rebound tenderness, RLQ tenderness, migration of pain from periumbilical to RLQ tenderness.
• After perforation: may initially feel relief, progresses to signs of peritonitis with frequent vomiting, fever, flexed right hip.

Case 3: Adolescent

• History:
  • 15-year-old female presents with vomiting
  • She has been feeling fine after a viral illness a few weeks ago but has been drinking and urinating more than usual.
  • She has been losing weight and feels fatigued.
  • Today she began having diffuse abdominal pain and started breathing quickly.
• Differential Diagnosis:
  • Drugs (prescribed or illicit) - Direct consequences or side effects, including cannabinoid hyperemesis syndrome.
  • Cyclic vomiting syndrome/abdominal migraine.
  • Inflammatory Bowel Disease.
  • Eating disorder (including bulimia).
  • Pregnancy.
  • Diabetic Ketoacidosis.
• Resolution:
  • You confirm the patient has new-onset DKA and initiate insulin therapy.

Complications of Vomiting

Select Common Associations

Time Course

Character

Physical Examination