Gastrointestinal Disorders Flashcards
Osmotic laxatives work by…
Increasing the water content in the stool
Explain the physiology that creates stomach acid.
The mucosal lining of the stomach contains Parietal cells.
The parietal cells can be stimulated by two neurotransmitters (Histamine or Acetylcholine) or a Hormone (Gastrin). These all have teir own receptors on the outside of the cell.
Stimulating the cells begins to pump out positively charged hydrogen ions (H+) into the stomach via the proton pump.
The negatively charged Cloride ions (Cl-) follow the H+, but leave the cell via their own chloride channel.
Once in the stomach, the H+ and Cl- ions combine to create HCl (hydrochloric acid) when it can begin to break down food in the stomach.
Philipa tells you on the morning medication round that she needs to have her lanzoprazole to “line her stomach”. Is this an accurate statement from Philipa?
Not quite.
Lanzoprazole is a Proton Pump Inhibitor (PPI) which reduces the amount of stomach acid being produced by preventing the parietal cells from moving hydrogen into the stomach to create acid.
Medications like NSAIDS can cause damage to the stomach lining (ulcers) that is worsened by the presence of too much stomach acid.
PPIs decreases stomach acid production which promotes the healing of gastric and duodenal ulcers and other inflamed gastrointestinal tissue areas.
True or False:
PPI can be bought over the counter.
True.
PPI in the form of esomeprazole is available over the counter at a reduced dose of 20mg.
Name two PPI medications.
Lanzoprazole
Omeprazole
Esomeprazole (OTC and prescription)
What are the pharmacodynamic effects of Omeprazole?
The proton pump within the parietal cell moves Hydrogen into the stomach, and Cloride follows where they combine to create hydrochloric acid.
A PPI like Omeprazole inhibits the proton pump, preventing Hydrogen ions from entering the stomach.
Less hydrogen leads to less Chloride leads to less stomach acid production.
What is GORD?
Gastro-oesophageal reflux disease.
Where gastric acid from the stomach is refluxed up into the oesphagus causing irritation of the internal mucosal lining of the oesophagus.
What are some of the short term effects or symptoms of GORD?
Pain (heartburn)
Hoarse voice
Difficulty lying flat
Cough
Aspiration (fluid into lungs).
What are some of the long term effects of GORD?
Scarring
Stricture (tightening of oesphagus)
Barrets oesphagus (pre-cancerous)
Increased risk of cancer
Ulcerations
Infections
Thinking along the lines of medication management, what should you consider when giving medications to a patient with GORD?
GORD increases the Ph of the gastric contents, which might inhibit the breakdown of some medications.
What are some of the physical assessment that should be carried out for a patient with GORD?
Onset/Duration
Pain on swallowing - due to ulcer or stricture
Assess BMI - due to increased internal pressure that obesity creates.
Dental erosion - coming up far enough to damage the back teeth.
Cough or wheeze - aspiration
Medication review.
What are some of the risks (red flag) associated with GORD?
Coughing up blood might indicate a rupture of an ulcer.
Infection might lead to sepsis.
Reduced swalled could lead to choking, aspiration or malnutrition.
Anaemia could indicate internal bleeding.
What are some of the holistic factors that should be considered with GORD?
Diet and fluid intake - potential triggers
Smoking - irritation/damage of mucosa
Hiatus hernia - increased internal pressure.
History of GORD
Anxiety - commonly associated condition.
Alcohol intake
What education might you give to a patient with GORD?
Avoid known triggers - smoking, coffee, fatty foods.
Lifestyle changes - Lie on left side, smoking cessation, smaller portions, eat 4hrs before sleep, elevate head when sleeping, lose weight, psychological therapies.
Medications that can worsen symptoms - NSAIDs, Betablockers, nutrates, calcium channel blockers, anticholingenics, anti depressants.
What over the counter medication might a patient take for GORD?
Antacids like rennies are made from Aluminium or magnesium compounds and work to reduce acidty of stomach contents.
These can cause delayed absorption of ACE inhibitors and antibacterials.
Alginates like Gaviscon. Made from seaweed and reduce acidity of stomach contents.
Alginates and antacids are often combined.
Weak PPI - Esomeprazole 20mg.
What are some common adverse effects of taking PPI?
Diarrhoea
Interferes with P450 enzyme which can increase or decrease metabolism of other drugs.
Parvati has had a course of PPI from her GP but is still experiencing symptoms of heartburn.
What type of medication might be prescribed as an alternative for long term use?
A Histamine 2 receptor antagonist might be used.
Examples include Cimetidine, famotidine and nezatidine.
Side effects include: GI disturbances, altered liver function.
What role do prostaglandins play in the GI system?
Prostaglandins support vasodilation of gastric mucosa, stimulate mucous production as well as producing bicarbonate (alkaline).
Terry is concerned that he’s taking too many medications and wants to stop his PPI. He was prescribed the PPI at the same time as his aspirin.
What is the physiological reason for this joint prescription?
Aspirin is a COX-1 inhibitor which interfers with the effect of prostaglandins.
Prostaglandins support the vasodilate of gastric mucosa and the production of mucous and bicarbonate (alkaline).
When the stomach can no longer protect itself from the acid contents, damage is likely to occur. There is also increased risk of this damage causing bleeding due to the anti-platelet effect of aspirin.
PPI is prescribed to reduce the amount of stomach acid produced, in doing so it reduces the potential for the stomach acid to cause harm to a stomach lining that is weaked by the COX-1 inhibitor (aspirin).
List 3 common causes of vomiting.
Motion
Sights or smells
pregnancy
drugs - opioids, anaesthetics, chemotherapy
vertigo
alcohol
migraine
Post-operative nausea and vomiting affects around 30% of patients, what is the timeline following an operation that vomiting can occur?
Up to 48hrs after surgery.
Which patient’s are considered high risk for Post-operative nausea and vomiting?
Females.
History of smoking, motion sickness, previous PONV, migraine or anxiety.
Patients who are taking opioids.
Identify 3 potential consequences of Post-Operative Nausea and vomiting.
Wound Dihiscence (opening/splitting of wound).
Bleeding
oesophageal perforation
aspiration
Dehydration - leading to electrolyte imbalance.
Increased recovery time and length of stay.
Distress and discomfort for them and others (and staff!)
There are three main neurotransmitters that can activate the signal to vomit, what are they called?
Histamine - H1
Dopamine - D2
Serotonin - 5-HT3
What are some of the physical assessments that should be carried out with PONV?
Onset, duration, frequency, quantity, other symptoms
Medication review
Abdominal examination
What are some holistic factors to be considered with PONV?
Absence of bowel sounds/ flatus - could indicate an Ileus
Signs of blood in vomit - could indicate perforation
Confusion - Dehydration and electrolyte imbalance.
Anaemia - blood less from internal bleeding.
What are some of the red flag risks associated with PONV?
Assess diet and fluid intake
History of motion sickness, PONV, smoking, anxiety or migraine
With regards to PONV, What is meant by prophylactic antiemetics?
These are antiemetics that are given before or very soon after the patient’s anaesthesia is removed so it is in their system already in the early stages of recovery.
Which three groups of medication are commonly used in the treatment of PONV?
Serotonin Receptor Antagonists (Ondansetron)
Dopamine Receptor Antagonists (Metoclopramide)
Anti-Histamines (Cyclizine)
True or False:
The ‘vomiting centre’ is located within the brain.
True.
Give 2 examples of vomiting stimuli and the neurotransmitter that they stimulate to cross the blood-brain barrier and interact with the vomiting centre directly.
Motion/Imbalance - Vestibular nucleus - Histamine
Changes in O2 levels - Chemoreceptors - Serotonin and histamine.
Changes in BP - Baroreceptors - serotonin and histamine
Tissue damage or injury - pain receptors - histamine
Some vomiting stimuli cannot interact with the vomiting centre directly, and first have to stimulate the chemoreceptor trigger zone which can cross the blood-brain barrier to induce vomiting.
Give two examples of these stimuli and their relevant pathways.
Chemotherapy/Opioids - act on CTZ independent of any other mediators
GI Disturbances, Surgery and some other drugs - release Serotonin or Dopamine which stimulates the CTZ, releasing Chemoreceptors that induce vomiting.
What are the four types of diarrhoea and how do they differ?
Osmotic - Additional water is being pulled into the bowel, occurs when soluable compounds aren’t absorbed properly.
Secretory - Results from increased secretion of fluid and electrolytes into the bowel with decreased absoption.
Inflammatory or Infective - Damage to mucosal cells affects absorption of fluids and electrolytes.
Abnormal motility - Increased movement without increased volume of stools.
Name one cause of Osmotic diarrhoea.
Coeliac disease
Malabsorption conditions
Name one cause of Secretory diarrhoea.
Medications
Infections
Name one cause of inflammatory/infective diarrhoea.
Medication
Ulcerative colitis
Crohn’s disease
Name one cause of abnormal motility diarrhoea.
Diabetes
Hyperthyroidism
Diarrhoea can be split into acute and chronic, what are the timelines for both of these conditions?
Acute - less than 14 days.
Chronic - more than 4 weeks.
Split the following conditions into causes for acute or chronic diarrhoea?
Irritable bowel disease
Coeliac Disease
Anxiety
Chrohn’s/colitis/functional bowel disorders
Drugs
Infection
Diabetes
Food Poisoning
Cancer
Hyperthyroidism
Acute
- Food Poisoning
- Infection
- Anxiety
- Drugs
Chronic
- Irritable Bowel Disease
- Coeliac Disease
- Crohn’s/Colitis/Functional bowel disorders
- Diabetes/Hyperthyroidism
- Cancer.
Identify two types of drugs that can cause diarrhoea.
Laxatives
Antacids
Antibiotics - broad spectrum, amoxicillin
Antihypertensives - ACE inhibitors, Beta blockers
Chemotherapy and radiotherapy
What are some of the red flag risks associated with Diarrhoea?
Blood, Masses, Weight loss, Dehydration - Cancer.
Antibiotics / Allergies.
Cancer treatments, recent surgery.
Fever, vomiting, exposure to infection. Stool Sample, blood tests for inflmmatory markers.
Loss of control of bowel movements.
What are some holistic factors to be considered with Diarrhoea?
New medications/vitamins/supplements.
Laxative use.
Alcohol or substance abuse.
Exposure to food items.
Travel abroad.
Anxiety
Fad diets
Diet and fluid intake
Family History.
What are some of the physical assessments that should be carried out with Diarrhoea?
Physical exam of abdomen and PR exam.
Onset, duration, frequency, severity, colour, smell, urgency.
Bristol Stool chart.
Lucas has had diarrhoea for 2 days.
What non-medical treatments and patient education would you give him to help him manage this condition?
Drink plenty of fluids.
Add semisolid and low fibre foods gradually.
Avoid certain foods like dairy, high fat or high fibre.
Take probiotics.
Oral electrolyte replacement drinks.
Lucas returns to clinic, now having had diarrhoea for 5 days.
What three priorities would we have in the treatment?
And which drugs might be used?
- Remove the cause of diarrhoea.
- Treat any infection.
- Treat dehydration.
Anti-diarrhoeal drugs
- Reduce bowel motility (loperamide hyrdochloride)
- Reduce amount of water in the bowel (Racecatotril)
- Last resort opioids (Codeine, morphine)
What are the 4 types of diarrhoea
- osmotic ( additional water pulled into bowel)
- secretory ( increased secretion of fluid and electrolytes with decreased absorption)
- inflammatory/infective ( damage to intestinal mucosa cells which affects absorption of fluids and electrolytes)
- abnormal motility (increased frequency of passing without increased volume)
