Nausea, Vomiting, Diarrrhea Flashcards
______: Unpleasant sensation that may,
but not necessarily, precede vomiting
Nausea
Emesis (vomiting)
Forceful oral expulsion of gastric contents
* Can allow for removal of toxins/poison
* Mechanism: Stimulation of multiple
pathways (see next slide)
Nausea mechanism
Gastric rhythm disturbance
* Gastric myoelectrical activity = 3
cycle/min
* ↑ (tachygastria) or ↓ (bradygastria)
frequency = NAUSEA
Nausea can cause autonomic changes:
- Increased (↑): salivation, heart rate,
respiratory rate - Decreased (↓): gastric tone, mucosal
blood flow
The physiological mechanisms of vomiting (Prepartory and expulsion steps)
Preparatory Steps
➢ The pyloric sphincter relaxes to allow entry of contents from the intestines
➢ The glottis closes
➢ Contractions begin in the duodenum and stomach
Expulsion Steps
➢ The lower esophageal sphincter relaxes
➢ Vomitus can move into the esophagus.
➢ Inspiratory (diaphragm, intercostals) and abdominal muscles contract
➢ The pylorus closes
➢ Vomitus is expelled into the mouth
DDx for causes of N&V
● Infectious Causes
● GI Disorders
● Endocrine Causes
● Misc. Causes
● Medications
● CNS Causes
Diarrhea
Passage of loose or watery stools:
* At least three times in a 24-hour period
* >200 g/day (difficult to measure)
Diarrhea pathophysiology
↑ water content of the stool
due to:
* Impaired water absorption
* Active water secretion by the bowel
* Acute
* Persistent
* Chronic
Diarrhea can generally be classified as:
- Infectious or noninfectious
- Inflammatory or noninflammatory
- Acute or chronic
Inflammatory Diarrhea
- Can be due to infectious (Invasive infections) and noninfectious causes.
- Symptoms include:
- Diarrhea with visible blood or mucus (invading tissue). Dysentery = bloody diarrhea
- Frequent, small-volume, and bloody stools
- May be accompanied by tenesmus, fever, or severe abdominal pain
- Stool will often contain leukocytes or leukocyte proteins
- If chronic, it is likely Inflammatory Bowel Disease
Non-inflammatory Diarrhea:
Most often caused by enterotoxin-producing organisms such as Vibrio cholerae and E.
coli, or by viruses that adhere to the mucosa and disrupt the absorptive and/or
secretory processes without causing acute inflammation or mucosal destruction
Symptoms of Non-inflammatory Diarrhea
- Watery
- No blood/pus (symptoms are due to osmotic and secretory effect)
Acute diarrhea:
<14 days
Persistent diarrhea duration
14-29 days
Chronic diarrhea duration
> 30 days
Diarrhea - Risk Factors
- Person to person exposure (ill contacts, daycare or senior-care centers)
- Exposure to contaminated food or water
- Exposure to animals (birds, reptiles often harbor salmonella)
- Medications
- Iatrogenic: Recent hospitalization within the last 3 months
Diarrhea - Emergent/Urgent Risk Factors
- Signs of inflammatory diarrhea: Fever, ↑ WBC, Bloody diarrhea, Severe abdominal pain
- Passage of > 6 unformed stools/24h
- Profuse watery diarrhea & dehydration
- Frail older patient (> 65 yrs)
- Immunocompromised pts
- HIV, DM
- Recent exposure to antibiotics
- Weight loss
- Pregnancy
- Sx > 7 days
Acute Diarrhea - Etiology
- Lasts < 2 weeks (~5-7 days)
- Acute onset
- Most commonly caused by:
- Infectious agents
- Medications
- Can be non-inflammatory or
inflammatory diarrhea
Acute Diarrhea - non inflammatory
- Watery, Non-bloody
- Caused by virus or non-invasive bacteria
S/S non-inflammatory acute diarrhea
- Periumbilical cramping
- Bloating
- Nausea
- Vomiting
- Prominent
Enterotoxigenic E Coli
(traveler’s diarrhea) is a common cause of ___
Acute non-inflammatory diarrhea
Inflammatory acute diarrhea etiology
- Fever
- Bloody (dysentery)
- Small volume < 1L/day
- B/C predominantly involves the colon
- Caused by virus or invasive bacteria: Shigella, Salmonella, Campylobacter, Amebiasis, C. diff, Enterohemorrhagic E. coli
S/S Inflammatory acute diarrhea
- LLQ cramping
- Urgency
- Tenesmus
- Fever
- fecal leukocytes present
Infectious dysentery MUST be distinguished from _____
acute ulcerative colitis
the Initial goal of the practitioner evaluating diarrhea is to Distinguish between _____
mild disease & those with serious disease
* >90% of pts = mild/self-limited
If diarrhea worsens & lasts > 7 days, labs:
- Fecal leukocyte
- Bacterial cx
- Obtain THREE samples of O&P
- > 10 days
- Hx of fairly recent travel
- HIV positive
- Oral-anal sex
General Nausea, Vomiting, & Diarrhea -
Treatment
- Diet
- Rehydration
- Antiemetics
- Antidiarrheal Agents
- Antibiotic Therapy
- Admit
Diet in treating N/V/D
- Generally, diet should consist of softer,
more easily digested foods, given in smaller
amounts (BRAT diet) - Bowel rest (i.e. - avoid):
* Large meals
* High-fiber food
* Fats
* Milk products
* Caffeine
* Alcohol
1st line rehydration treatment in N/V/D
Oral rehydration
* If feasible the solution should contain
the following:
* Glucose, Na+, K+, Cl-, HCO3
, Citrate
* Oral electrolyte solutions:
* Pedialyte, Gatorade, Oral
rehydration tablets
* Ice chips
* IV fluids – SEVERE dehydration (1 liter Normal Saline (NS) or Ringer’s
Lactate (RL) IV over 60-90 min)
The most critical therapy in diarrheal illness is
Hydration
Antimicrobial Therapy
- NOT warranted for all patients
- Administered either empirically (based on likely causes) or targeted (based on
testing)
Targeted abx treatments for giardia
metronidazole
Targeted abx treatments for amebiasis
metronidazole
Targeted abx treatments for travelers diarrhea
Cipro or azithromycin
Targeted abx treatments for E. coli
Supportive
Targeted abx treatments for C. Diff
Metronidazole or vancomycin
Chronic Diarrhea
- Diarrhea present > 4 weeks
Most common causes of chronic diarrhea
- Medications
- Lactose Intolerance
- Irritable bowel syndrome
Chronic Diarrhea - labs
- CBC, TSH, CMP (albumin, calcium, LFT’s) TSH, vitamin A & D, INR, ESR, CRP, celiac serologic testing
Routine stool studies:
- O&P
- Fecal Electrolytes (osmotic gap- secretory)
- Qualitative staining for fat (sudan stain)
- Occult blood (FOBT)
- Leukocytes
- Stool culture: routine identifies
Salmonella, shigella, campylobacter
Staphylococcus aureus
Gram positive cocci in clusters (grapes)
● Facultative anaerobe (ATP via O2
or fermentation)
● Can cause many infections including gastroenteritis
● Can grow in food
● Produces Enterotoxin
● Ingested toxin → 12-24 hours of:
● Abdominal pain
● Nausea
● Vomiting (Q15-30 min X 12-24hrs)
● Diarrhea
Bacillus cereus
Gram positive rods
* Aerobic, spore forming, toxin-producing
* Deposits spores in food which survive initial cooking
* Heat activates the spores → causes bacteria
dump their enterotoxin into the food (the
bacteria are killed by the heat)
* Ingested toxin = nausea, vomiting,
abdominal pain, & diarrhea
* Lasts 12-24 hours usually, self-limited
* Fried rice is an important cause of Bacillus cereus
Clostridium difficile
“C Diff” or Pseudomembranous Enterocolitis
* Small amount normally found in the intestine (controlled)
* Gram stain: Gram Positive Rod
* Anaerobic bacteria, spore-forming, toxin-producing
* Spores are often found in hospitals & nursing homes
* Fecal-oral ingestion of spores → intestinal colonization
Escherichia coli
- Part of normal colon flora
- If it gains virulence factor (mutation, plasmid exchange, etc), E coli can cause
human disease. - Diarrhea, UTIs, neonatal meningitis, Gram negative sepsis
- Outbreaks can occur with fecal contamination of water
3 important strains of E. Coli
- Enterotoxigenic: Non-invasive, toxin induces watery diarrhea (travelers diarrhea)
- Enterohemorrhagic Escherichia coli (EHEC) : Invasive diarrhea due to Shiga-like toxin.
- Enteroinvasive: Invasive diarrhea
HUS triad (hemolytic uremic syndrome)
Hemolytic anemia
Acute renal failure
Thrombocytopenia
Triad is life
Threatening
1% in adults
3% in children
Vibrio cholerae (Cholera)
● Similar action to E. Coli but much more severe
● Influx of Na+
into lumen pulls water with it
● Copious watery diarrhea (up to 1 L / hr)
● “Rice Water Diarrhea”
● Fishy odor
Treatment for cholera
Cipro® or azithromycin
Salmonella
- Salmonella Gastroenteritis-
- Most common form of Salmonella
- Sx - occur 8-48 hr post ingestion:
- Fever
- Abdominal pain
- Mucous
- Bloody diarrhea
Treatment of Salmonella
- Supportive
- Abx do NOT shorten dz course
Severe form of salmonella
Typhoid Fever
* Rx: Cipro (1st line), azithromycin,
cephalosporins or
trimethoprim/sulfamethoxazole
A MAJOR complication of Salmonellosis = _____
Enteric fever (Typhoid fever)
Symptoms of typhoid fever
○ SYSTEMIC - gets into the bloodstream
■ Meningitis
■ Endocarditis
■ Osteomyelitis
○ Weight loss
○ Rose spots (transient rash on abd/back)
● Culprits are Salmonella typhi & Salmonella paratyphi
Shigella
“Shigella dysenteriae”
* NEVER found in normal GI flora
* Shiga toxin: Cytotoxic to intestinal
epithelium
S/S shigella
- HIGH Fever
- Bloody/mucoid diarrhea (invasive)
- Purulent
- Abdominal cramping
- Tenesmus & rectal spasms
Treatment of shigella
- Supportive treatment
- Severe = Ciprofloxacin or TMP-SMX
Intestinal Complications of Shigella
- Proctitis
- Rectal Prolapse
- Toxic Megacolon
- Intestinal obstruction
- Colonic perforation
Campylobacter Jejuni S/S
- Fever
- Bloody diarrhea
- Possible association with Guillain-Barre Syndrome
- Caution - can mimic appendicitis: often severe abdominal pain
occurs PRIOR to onset of diarrhea - Key = Rebound/guarding usually absent
- Can mimic inflammatory bowel disease colitis: starts in jejunum &
progresses to cecum & colon. - Acute colitis & bloody diarrhea
How do differentiate campylobacter jejuni from appendicitis
Rebound/guarding usually absent
The two most common GI viruses are:
- Rotaviruses
- Norwalk Virus
Leading cause of dehydrating
gastroenteritis in children worldwide
Rotaviruses
= Most Common
Sources of Transmission for norovirus
Food handlers
Treatment of CMV
- Antiretrovirals (in HIV pts)
- Ganciclovir
- Prophylaxis in HIV pts when
CD4 < 50
Amebiasis Tx:
- Metronidazole + Iodoquinol
Giardiasis Tx
metronidazole
