GI Flashcards
H2 Receptor Antagonists
-tidine
Action
Inhibit acid production
Raise gastric pH
Decreases gastric volume
There are a ton of drug interactions with what H2 receptor antagonist?
Cimetidine > Ranitidine > Famotidine = 0 Inhibits cytochrome P450 system Prolongs the action of drugs - theophylline, aminophylline phenytoin, halothane, phenobarbital, diazepam, TCAs, meperidine propranolol, labetolol, CCB coumadin lidocaine quinidine
What is a disadvantage of oral antacid administration?
Increase in gastric volume
*Non-particulate antacids are preferred
Metoclopramide
Action
Increases tone of LES Decreases tone of pyloric sphincter Relaxes duodenum Increases gastric motility Decreases gastric volume *NO effect on gastric pH (Also a competitive dopamine antagonists )
The incidence and severity of aspiration pneumonitis are reduce if…
Gastric pH > 2.5
Gastric volume < 25 mL
Which antiemetics should be avoided in the patient with Parkinson’s disease?
Competitive dopamine antagonists
Droperidol, prochlorperazine, metoclopramide
What is the most common side effect of ondansetron?
Headache
What is the most powerful agent for decreasing acid secretion?
Omeprazole
Inhibits the H pump
Increases gastric pH
?effect on gastric volume
Describe the musculature of the esophagus.
Pharynx and upper 1/3 = striated muscle (glossopharyngeal and vagus)
Lower 2/3 = smooth muscle (vagus and esophageal myenteric)
Last 3-5 cm = LES - smooth muscle + skeletal muscle of the crural diaphragm
What type of muscle is the pyloric sphincter?
Smooth muscle
What type of muscle is the GI tract?
2 layers of smooth muscle
Inner circular layer
Outer longitudinal layer
What is the gastric pH range in the fasted patient?
1.6-2.2
List 7 conditions that may delay gastric emptying.
- Obesity
- Pregnancy
- Opioids
- DM
- Trauma
- Pain
- Anxiety
What is the purpose of CCK?
Released in response to the presence of fats
Stimulates gallbladder contraction and the release of pancreatic enzymes
Inhibits gastric motility
Allows for the digestion of fats
Bile vs. gastric vomitus?
Bile - alkaline
Gastric - acid
What acid-base disturbance will be seen with projectile vomiting?
Metabolic alkalosis
What causes serum alkaline phosphatase to increase?
Biliary tract obstruction
Pancreatitis
Associated with: dehydration, hypocalcemia, hyperglycemia, ARDS
Evaluate for: malnutrition, abnormal liver function, alcoholism
Do most patients with hiatal hernia have symptoms of reflux esophagitis?
NO
Where are most carcinoid tumors (aka enterochromaffin tumors) found?
GI tract (esp. in the appendix) Hormones releases are carried to the liver and metabolized first
What hormonal mediators are involved in carcinoid syndrome?
- Serotonin*
- Bradykinin
- Histamine
- Prostaglandins
- Kallikrein
What does elevated 5-HIAA in the urine indicate?
The presence of serotonin
Carcinoid syndrome
What are the 5 clinical manifestations of an active non-intestinal carcinoid tumor?
- Cutaneous flushing
- Bronchospasm
- Diarrhea
- Large swings in arterial BP
- SVT
List 4 stimuli for the release of hormones from a carcinoid tumor.
- Catecholamines
- Histamine
- Hypotension
- Tumor manipulation
The patient is taking large doses of either an aluminum-based or magnesium-based antacid…what could be the problem?
Hypophosphatemia
The patient has CRF and is taking antacids for gastric distress. What could be the problem?
Hypercalcemia
Calcium-based anacid - Tums
