L1 - Nausea and Vomiting Flashcards
what are the major physiologic functions of the GI system (just the basic functions)
- digest food
- absorb nutrients into blood stream
what happens to unabsorbed nutrients and wastes in the GI system
they are collected in te large intestine for elimination
What are the functions of the GI system
- ingestion - solid food and liquid enter oral cavity
- mechanical digestion and propulsion - crushing/shredding of food in oral cavity and churning in stomach
- chemical digestion - chem and ezymatic breakdown of food into small organic molecules that can be absorbed by the digestive epithelium
- secretion - The release of water, acids, enzymes, buffers, and salts by the digestive tract epithelium and by accessory organs
- absorption - Movement of nutrients across the digestive epithelium and into the bloodstream
- defecation - indigestible foods are compacted into material waste that is eliminated by defecation
what three parts is the GI system broken into? what do each contain?
- upper - mouth, esophagus, stomach
- middle duodenum, jejunum, ileum
- lower - cecum, colon, rectum
What features of the GI system increase surface are for absorbing nutirents
its lined with permanent ridges and temporary folds (stomach rugae)
what are the accessory organs of the GI system? what are their jobs?
- salivary glands
- liver
- pancreas
these produce secretions to aid in digestion
what is the definition of vomiting
- Usually follows nausea, including retching (spasmodic respiratory and abdominal movements)
- Oral expulsion of gastrointestinal contents due to contractions of the gut and thoracoabdominal wall musculature
what is regurgitation
- The effortless reflux of liquid or food stomach contents
- “Burping up” food contents
what is rumination
The chewing and swallowing of food that is regurgitated after meals
the motor function of the gut is controlled at three main levels…. what are they?
- parasympathetic and sympathetic nervous system
- enteric brain neurons
- smooth muscle cells
normal function of the GI tract involves what interaction?
interaction between the gut and the CNS
what does nausea correlate with
with a shift in the normal 3-cycle-per minute gastric myoelectrical activity (muscle contraction and relaxation)
stomach should contract and relax every 3 min. nausea disrupts this
what is tachygastria
increased rate of electrical activity in the stomach (4+ cycles/min)
what is bradygastria
decreased rate of electrical activity in the stomach (less than 2 cycles)
what are the 4 different sources that can stimulate vomiting
- afferent vagal fibers from the GI viscera - rich in serotonin 5-HT3.
- fibers of the vestibular system - high concentrations of.histamine H1.
- higher CNS centers
- chemoreceptor trigger zone - rich in opioid, serotonin 5-HT3, neurokinin 1, and dopamine 2 receptors.
what could cause vomiting via stimulation of the afferent vagal fibers from GI viscera
GI distention, mucosal or peritoneal irritation, infections
what could cause vomiting via stimulation of the Fibers of the vestibular system
sea- sickness
dizziness
what could cause vomiting via stimulation of Higher CNS centers
certain sights, smells, or emotional experiences may induce vomiting
what could cause vomiting via stimulation of chemoreceptor trigger zones
- this is located outside blood-brain barrier in the area postrema
- stimulated by drugs, chemo agents, toxins, hypoxia, uremia, acidosis, radiation therapy
what steps should be followed in both urgent care and outpatient setting for patients with nausea/vomiting
- seek out etiology and take into account whether s/s are acute or chronic
- identify consequences or complications of n/v (fluid depletion, hypokalemia, met alkalosis)
- provide target therapy when possible (surgery for bowel obstruction or malignancy)
what are some typical causes of acute symptoms w/o severe abd pain
should be asked about med, diet changes and sick contacts
also
* typically caused by food poisoning
* infectious gastroenteritis
* drugs
* systemic illnesses
what is suggested by acute onset of severe abdominal pain and vomiting
- suggests peritoneal inflammation
- acute gastric/intestinal obstruction
- pancreatobiliary disease
what could persistent vomiting suggest?
- suggests pregnancy
- gastric outlet obstruction
- gastroparesis
- intestinal dysmotility
- psychogenic disorders (think bulimia)
- CNS/systemic disorders
what does morning vomiting suggest?
- pregnancy
- uremia
- alcohol intake
- increased intracranial pressure
what should you suspect in patients with a hx of cannabis use
cannabinoid hyperemesis syndrome
how does cannabinoid hyperemesis syndrome present
- recurrent episodes of NV and ab discomfort
- typically occurs in younger adults with hx of frequent chronic cannabis use
- improvement with hot shower or bath
what should you suspect if a patient vomits immediately after meals
- bulimia - TEETH EXAM
- other psychogenic causes
what should you suspect if a patient vomits undigested food one to several hours after meals
- gastroparesis
- gastric outlet obstruction - may hear a succussion splash
what neurologic symptoms should you ask about with NV
headache
stiff neck
vertigo
focal weakness/paresthesias
feculent vomiting = intestinal obstruction
what is hematoemesis
vomiting of blood or coffee like material
what lab studies should be ordered for CC of NV, why?
- CBC - infection, anemia
- CMP - Electrolyte disturbances, liver function, azotemia, metabolic alkalosis from loss of gastric contents
- Amylase and lipase - pancreatic enzymes
- b-hCG
what imaging could you do in a patient whose CC is NV
Xrays - flat and upright abdominal films
usually only in pts with severe or suspicion of mechanical obstruction
what would Xrays show in small bowel obstruction
intestinal air-luid levels with reduced colonic air
what would Xrays show in ileus
diffusely dilated air-filled bowel loops
what additional testing may be done in NV if initial testing is non-diagnostic
- EGD - ulcers, malignancy, obstruction, food residue.
- CT scan - partial SBO
- colonoscopy - detects colonic obstruction, malignancy, inflammatory conditions
- US - intraperitoneal inflamm, choleslithiasis
- MRI - inflammation in chrons
- GI motility testing - underlying motor disorders, delayed gastric emptying, functional dyspepsia
what are complications of NV
- Volume Depletion/Dehydration
- Electrolyte Disturbances
- Aspiration
- Mallory-Weiss Tear
- Boerhaave Syndrome (Esophageal Rupture)
what is the treatment for NV
- correct abnormalities if possible
- hospitalization if dehydration
- once oral intake is tolerated and restarted on low fat liquids
why do we use low fat liquids when reintoducing food to patients recovering from NV
because lipids delay gastric emptying
what is the tx for mild-moderate NV
- Clear liquids (broths, tea, soup, carbonated beverages)
- Advance to small quantities bland food (crackers)
- Antiemetic medication
what is the treatment for mod-severe NV
- Hospitalization with IV (isotonic) fluids
- Antiemetic medication
- NG tube in certain situations (i.e. small bowel obstruction/gastric)
children and infants with difficult IV/IO access can be rehydrated using what?
NG tube:(
how is oral rehydration achieved in a pediatric patient
by giving 50–100 mL/kg of a glucose–electrolyte solution over 4 hours. In children, age-appropriate diet and breast-feeding may resume as soon as possible. In either case, start with small doses of oral fluid and slowly increase the amount.
what is the goal of fluid replacement therapy
The goal of replacement therapy is to correct existing abnormalities in volume status and/or serum electrolytes.
how do you assess volume deficit
- weight loss ( if pre and post fluid loss weight is known)
- clinical and lab parameters (BP, jugular venous pressure, urine Na conc, urine output.)
what is the rate of replacement for severe volume depletion or hypovolemic shock
- at least 1 or 2 liters of isotonic fluids given as rapidly as possible in an attempt to restore tissue perfusion
- contones at a rapid rate until clinical signs of hypovolemia improve
what is the rate of replacement for mild-mod hypovolemia
- rapid fluid resuscitation is not necessary
- Induce positive fluid balance = administration of fluid at a rate that is 50 to 100 mL/hour greater than estimated fluid losses.
what types of fluid replacement would be needed in certain electrolyte disorders
- regular hypovolemia = isotonic saline
- hyper/hyponatremia should be corrected slowly since rapid correction is harmful
- potassium depletion = potassium replacement
- metabolic acidosis = sodium bicarb
Caution with parenteral fluid bolus doses in following patient populations:
infants, patients with poor systolic ejection fraction, kidney disease, chronic severe hyponatremia (without neuro deficits that require hypertonic saline) and DKA in children.
what class drug is ondansetron (zofran) and what is the MOA
- class is serotonin 5-HT3 receptor antagonist
- MOA = 5-HT3 receptors present both peripherally and centrally, Blocks serotonin from binding to 5-HT3 receptors, Blocking stimulation of “vomiting center” in medulla
what are indications for ondansetron (zofran)
- Acute N/V
- Postoperative N/V
- Chemotherapy related N/V
- Hyperemesis gravidarum? (avoid in 1st trimester d/t rare chance of cleft palate)
how is ondansetron (zofran) metabolized
by the liver
caution in hepatic impairment
what should you monitor for in the use of ondansetron (zofran)
- if patient is pregnant
- QT prolongation
what are SE of ondansetron (zofran)
- HA
- Diarrhea/Constipation
- Fatigue, malaise
- Dizziness
- Pruritus
what class is Scopolamine (transdermscop)/ meclizine/doxylamine and what is the indications for this drug
- anticholinergic/antihistamine
- indicated in Motion Sickness, vertigo, migraines. COmbined with oral Vitamin B6 and doxylamine for pregnancy (1st line in NV while pregnant).
- also indicated in post operative NV
what are common SE of scopolamine/meclizine/doxylamine? what is the dosage form of this med
- xerostomia, urinary retention
- dizziness
- drowsiness, mydriasis
- dosage form = patch!
what class is promethazine (phenergan). what is it indicated for
- class - 1st generation antihistamine; blocks H¹ receptors, special mention for Dopamine Receptor Antagonist (Phenothiazine); with H1 blocking as well
- indicated for acute NV
what is promethazine (phenergan) metabolized by
the liver CYP450
what are serious adverse reactions for promethazine (phenergan)
- Respiratory Depression
- Seizures
- Leukopenia
- Thrombocytopenia
- Hallucinations
- Extrapyramidal Side Effects
- Bradycardia
what are common SE of promethazine (phenergan)
- Sedation
- Blurred Vision
- Confusion
- Xerostomia
- Dermatitis
- Urinary retention
- Constipation
what is the BBW for promethazine (phenergan)
- resp depression
- tissue injury/necrosis
what are CI for promethazine (phenergan)
- resp depression
- children under 2
who should you caution promethazine (phenergan) in?
- Elderly
- CNS depression
- Asthma/COPD
- Glaucoma
- BPH
- Cardiac Ds
- Hepatic Ds
- Seizure Ds
what pregnancy category is promethazine (phenergan)
category C
metoclopramide (reglan) is what class and what is the MOA
- class = prokinetic
- Increases peristalsis primarily by inhibiting dopamine
- enhances response to acetylcholine of tissue in upper GI
- enhances motility and accelerated gastric emptying
- increases lower esophageal sphincter tone
what are indications for metoclopramide (reglan) and how is it metabolized
- indications: NV, gastroparesis, refractory GERD
- minimal liver metabolism, renally excreted
what are serious SE for metoclopramide (reglan)
- Extrapyramidal Side Effects
- Neuroleptic malignant syndrome
- Seizures
- Depression/Suicidal Ideations
- Leukopenia/Agranulocytosis
- CHF, arrhythmias
- HTN
what are common SE of metoclopramide (Reglan)
- Diarrhea
- Drowsiness
- Restlessness
- Anxiety/Insomnia/Depression
- HA/Dizziness
- Hormonal Disorders
- HTN
what is the BBW of metoclopramide (Reglan)
- tardive dyskinesia
what are CI for metoclopramide
- seizure Ds
- GI obstruction
what pregnancy category is Metoclopramide (reglan)
pregnancy category B
what are cautions for metoclopramide (reglan)
- HTN
- Parkinsons
- CHF
- Depression
- DM
- Renal Impairment
what are other medications that can be used for NV
- neurokinin receptor antagonists (aprepitant/emend) - given during chemo with dexamethasone
- dexamethasone - post op NV, chemo (additive agent)
- lorazepam = benzo (xanax) anticipatory NV with chemo (given along with zofran to help with chemo induced vomiting)
