Nausea and Vomiting Flashcards
Three phases of emesis
Nausea • Subjective feeling of “impending vomiting”
Retching • Spasmodic contractions of the diaphragm and intercostal muscles (“respiratory muscles”) with
epiglottis closed
Vomiting • Oral expulsion of GI contents
order the emetic sequence
2 Peristalsis reverses direction: • pushes stomach contents out of mouth. 3 Epiglottis closed to prevent pulmonary aspiration 4 Contraction of diaphragm + abdominal muscle. 5 Soft palate is raised to prevent GI contents going into nasopharynx. 6 Relaxation of lower esophageal sphincter.
Contraction of diaphragm + abdominal muscle. – Relaxation of lower esophageal sphincter. – Peristalsis reverses direction: • pushes stomach contents out of mouth. – Soft palate is raised to prevent GI contents going into nasopharynx. – Epiglottis closed to prevent pulmonary aspiration.
Aspiration pneumonia, choking
when food, saliva, liquids, or vomit is breathed into the lungs or airways leading to the lungs, instead of being swallowed into the esophagus and stomach
Central regulation of vomiting occurs in two separate
areas of the medulla:
• Emetic center (vomiting center), medulla oblungata
– Mediates vomiting from all causes
– Coordinates the respiratory, GI and abdominal musculature involved in vomiting
Nucelus of cells in medulla Recognizes signals
• Chemoreceptor trigger zone (CTZ), area postrema
– Activate the emetic center
– Responds to blood borne endogenous or exogenous
molecules that activate emesis
4th ventricle, near brainstem
Slightly out of BBB so responds to circulation
describe the Vestibular apparatus pathway
– Labyrinth stimulation of vestibular cochlear nerve (cranial nerves VIII)
– Stimulates vestibular nuclei in brain stem – contain histamine and
muscarinic (Ach) receptors
– Ach receptors – activate emetic center
– NA receptors – stabilize emetic center
Stimulus from innter ear to brain
describe cortical stimulation and visceral stimulation
• Cortical stimulation (cognitive)
– Emotions, smells, taste, sight
Panic, anxiety Stimulate cerebral cortex
Noxious smell
• Visceral stimulation
– Autonomic afferents from pharynx and GI
– MI, appendicitis
Internal organs
Specially coming from GI tract
Appendicitis, heart attachk can stimulate it to happen
• Emetic reflex involves multiple receptor (7):
Serotonin (5-HT3) Dopamine (D2) Acetylcholine (Ach, muscarinic, M1) Histamine (H1) Cannabinoid (CB1) Neurokinin-1 (NK-1) – substance P Opioid
Causes of Nausea and Vomiting
• Motion sickness • NV of pregnancy • Postoperative • Medications • Disease – Infections – Cardiac – Gastrointestinal – Metabolic/endocrine causes – Central Nervous System – Psychiatric
Approach to NV
Three step approach:
1. Recognize and correct any consequences of the
vomiting e.g. dehydration, electrolyte abnormalities
2. Identify underlying cause for NV.
3. Treat underlying cause. If no etiology can be
determined use empiric therapy to treat symptoms.
Assessment of NV
• Assess patients signs and symptoms: – Severity of NV – Onset and frequency of NV – Appearance vomited material – Aggravating or remitting factors – Associated symptoms: fever, abdominal pain, weight loss, diarrhea, headache/migraines etc.
red flags
Symptoms of dehydration – Persistent vomiting – Blood or “coffee-grounds” in vomitus – Blood in stools (black or tarry) – Difficulty swallowing – Abdominal pain – Weight loss (unintended) – Altered mental status – Age >55 years
• Types of physical examination:
Suken eyes, low urine ouput, dry mouth, lips, stringy saliva, dry mucous membranes, thirsty headache
Sunken eyes in children, decrease in skin turgor, stays elevated when pinched
– Abdominal examination – Neurologic examination – Signs of psychiatric cause • General examination/diagnostic tests to rule out potential causes and/or complications
Complications of Vomiting
• Fluid, electrolyte and metabolic alterations.
– Dehydration, hypotension, hemoconcentration, oliguria, muscle weakness, cardiac arrhythmias
• Aspiration pneumonia
• Prolonged vomiting:
– Nutritional deficiencies - malnutrition
– Esophagitis
– Lacerations at the gastroesophageal junction
– Multiple purpuric lesions: long durations where blood vessels on face conversed
– Dental caries/erosions
Goals of Therapy
- Relieve symptoms
- Prevent complications
- Prevent recurrence or reduce the frequency of episodes
- Improve patients quality of life
Non-pharmacologic Therapy
• General approaches:
– Adequate hydration
– Avoid noxious odors/foods that cause nausea
– Eat frequent, small meals
– Decrease physical activity
– Gear approach to cause/etiology of NV
• e.g. if labyrinthine changes produced by motion then assume stable physical position
Supportive care
Prevent and relieve symtpoms
Stable visual line for motion sickness
Maintain fluid intake
how much water?
– Depends on amount of vomiting
– Normal amounts – adults need 1 – 3 L of total water intake
• Amount required will depend on amount lost with vomiting (and/or diarrhea)
– Moderate or severe vomiting may require electrolyte replacement:
• e.g. oral rehydration solutions (OHS)
