HX2.2 GI Symptoms in Advanced Disease Flashcards
What are the three main challenges in managing GI symptoms in advanced disease?
Nausea & Vomiting.
Constipation.
Bowel Obstruction.
What is nausea?
“A subjective unobservable phenomenon of an unpleasant sensation experienced in the back of the throat and the epigastrium that may or may not result in vomiting.”
What is vomiting?
The forceful expulsion of the contents of the stomach, duodenum or jejunum through the oral cavity
Describe the vomiting sequence
- Nausea and increased salivation.
- Peristalsis is reversed stomach relaxation.
- Glottis closes off trachea to prevent aspiration.*
- Breath is held mid inspiration.
- Abdominal muscles contract, lower esophageal sphincter and esophagus relax, expelling vomit.
What is the logical approach for treating nausea + vomiting?
- Signs & Symptoms.
- Causes
- Neurophysiology
- Drug Receptors
- Drugs
What information should be elicited during the Hx for N+V?
- Nausea? Retching? Vomiting?
- When: did it start? Time(s) of day?
- Constant/not?
- What: does vomit look like? Amount? Blood?
- How: did it start?
- How has it been treated so far? - Exacerbating/Relieving factors?
What are the possible categories of N+V causes
Psychological Raised ICP Vestibular Vagus Nerve Liver Damage GI Damages
Which receptors mediate psychological causes of N+V?
Benzoreceptors
Which receptors mediate raised ICP causes of N+V?
Histamine H1 receptor (H1)
Which receptors mediate vestibular causes of N+V?
H1 + ACHM (muscarinic cholinergic receptors)
Which receptors mediate vagal causes of N+V?
ACHM
Which receptors mediate Toxin (blood) causes of N+V?
- D2 (Dopamine 2)
- 5HT2 (5-Hydroxytryptamine receptors/serotonin receptors)
- 5HT3
- 5HT4
Which receptors mediate liver damage causes of N+V?
5HT4
Which receptors mediate GI damage causes of N+V?
D2
5HT3
5HT4
Against which receptors is Domperidone effective?
D2++
Against which receptors is Metaclopramide effective?
D2++
5HT3+
5HT4++
Against which receptors is Haloperidol effective?
D2+++
Against which receptors is Cyclizine effective?
H1++
ACHM++
Against which receptors is Ondansetron effective?
5HT3+++
Against which receptors is Hycozine effective?
ACHM+++
Against which receptors is Prochlorperazine effective?
D2++
H1+
Against which receptors is Chlorpromazine effective?
D2++
H1++
ACHM+
Against which receptors is Levomepromazine effective?
D2++
H1+++
ACHM++
5HT2+++
Which drug/s are usually employed against psychological causes of N+V?
Benzodiazepines
Non-pharma treatments
Which drug/s are usually employed against raised ICP causes of N+V?
Cyclizine (H1)
Steroids
Which drug/s are usually employed against vestibular causes of N+V?
Hyoscine (Achm)
Cyclizine (Achm,H1)
Which drug/s are usually employed against Vagal causes of N+V?
Hyoscine(Achm)
Which drug/s are usually employed against Liver causes of N+V?
Metoclopramide(5HT4)
Steroids
Which drug/s are usually employed against GI causes of N+V?
Metoclopramide (D2)
Ondansetron (5HT3,4)
Steroids
Which drug/s are usually employed against Toxic causes of N+V?
Haloperidol (D2)
Ondansetron (5HT2)
Metoclopramide (5HT3,4)
Which neurological structures mediated the vomiting reflex?
The CNS
Vestibular System (H1, M1)
Cranial Nerves IX, X
Feed into…
The Vomiting Centre +
The Chemoreceptor Trigger Zone
Located in the Medulla Oblongata
Which anti-emetics are considered to also be prokinetics?
Target = D2 antagonist
Metoclopramide (maxalon) 10mg TDS PO.
Crosses BBB = central effects.
5HT3 (at high doses), D2, Ach.
Extrapyramidal side effects
Domperidone (motilium) 10mg TDS PO.
D2
Side effects rare. May exacerbate colicky abdominal pain.
Erythromycin (not indicated as 1st line prokinetic)
Motilin agonist = triggers wave of peristalsis.
Useful in denervated Gut.
What are the side effects of the anticholinergics?
E.g. Hycosine, atropine
Dry mouth, constipation, blurred vision, urinary retention.
Sedation, agitation, seizures (if crosses BBB)
Side effects of the Phenothiazines & Butyrophenones:
Haloperidol
Levomepromazine
Prochlorperazine
Side Effects: Dystonia (esp. Stemetil). Anticholinergic effects. Postural hypotension. Sedation.
What are the side effects of the antihistamines?
Cyclizine
Promethazine
Dimenhydrinate.
Cyclizine may precipitate in syringe drivers.
Urticaria & drug rash
Anticholinergic side effects – dry mouth, urinary retention etc.
What is the purpose of corticosteroids? MOA?
1.Reducing oedema
2.Reducing inflammation
Reduces tissue damage
Inhibition of release of mediators of emesis
MOA:
increase activity of 5HT3 antagonists after chemotherapy
Reducing oedema & inflammation
Inhibition of release of mediators of emesis
Give an example of a corticosteroid?
Dexamethasone
What are the side effects of corticosteroid use?
Adrenal cortical atrophy. Anti-inflammatory/immunosuppressive effects. Avoid live vaccination to pts on steroids. Osteoporosis. Hypertension Hypokalemia Diabetes mellitus Peptic ulceration. Renal failure. Liver failure. Epilepsy.
Give some examples of non-pharmacological methods of managing N+V?
Control of malodor from colostomy, fungating tumour or decubitus ulcer
An environment away from the sight and smell of food
Small frequent meals
Avoid fatty, spicy, highly salty foods
Behavioral approaches
Distraction, relaxation
Massage
Acupuncture (Studies show effectiveness in chemo-induced nausea and anticipatory nausea)
How should antiemetics be taken?
Give antiemetics regularly - not P.R.N.
Which antiemetics should be used where intestinal obstruction is also present?
Prokinetics
What are the steps if N+V present despite optimal prophylactic therapy?
1.Rule out reversible causes.. Bowel obstruction, gastroparesis, gastritis medications brain mets, vestibular dysfunction electrolyte imbalance
2.Control episodes of nausea
Give a different agent from another drug class.
Consider route of administration
consider regular use rather than PRN
3.Plan adjusted prophylactic regimen for next cycle of treatment.
What is constipation?
Constipation is characterized by difficult or painful defecation associated with infrequent bowel evacuations (+/- hard, small faeces, abdominal fullness and pain)
50-80% palliative care patients
What are the possible complications of constipation?
Pain – colic or constant abdominal discomfort Nausea & vomiting Anal fissures Anal pruritis Haemorrhoids Faecal impaction and intestinal obstruction Spurious (overflow) diarrhoea Faecal incontinence Urinary retention or incontinence Delirium Cost - £43 million/year
What are the 5 classes of pharmacological interventions for constipation?
- Stimulants
- Faecal Softeners
- Osmotic Agents
- Bulk Forming Agents
- Rectal Agents
Give some example of stimulant constipation meds?
Bisacodyl
Danthron
Senna
Give some example of faecal softeners?
Docusate
Give some example of osmotic agents?
Lactulose
Magnesium Salts
Polyethylene Glycol
Give some example of bulk forming agents?
Methylcellulose
Ispaghula husk
Give some example of rectal agents?
Bisacodyl
Glycerol
Microlax
High phosphate enema
What should always be prescribed with an opioid?
A laxative
What options should be considered where a conventional laxative is not working?
Consider changing to a less constipating formulation
Opioid antagonists
What are the principles of constipation management?
Regularly assess, be proactive
Consider factors such as privacy, comfort
Increase fluid and fibre as tolerated
Encourage mobility if patient is able
Start prophylactic laxatives when starting opioid drugs
Use a combination of a stimulant and a softener/osmotic laxative
Use oral laxatives in preference to rectal measures
How is bowel obstruction classified?
May be intramural, intraluminal or extra luminal
At each level, the obstruction can be functional (paralytic) or organic (mechanical), or both
Partial or complete
Transient (acute) or persistent (chronic)
What are the clinical features of bowel obstruction?
GI symptoms depend on the site of obstruction
Continuous abdominal pain is present in ~90%
Intermittent colic ~ 75%
May not have abdominal distension
Vomiting develops early and in large amounts in gastric, duodenal and SB obstruction
Bowel habit ranges from constipation to diarrhoea
Bowel sounds vary from absent (functional obstructions) to hyperactive and audible (borborygmi)
Tinkling bowel sounds NOT always present
What radiological investigations can be used to dx bowel obstruction?
MUST BE CONSISTENT WITH GOALS OF CARE
Plain abdominal film
Supine and standing
Contrast radiography
Helps to evaluate dysmotility, partial obstruction and to define the site and extent of obstruction
CT
Useful in evaluating global extent of disease
What are the goals of pharmacological management of bowel obstruction?
1.Anti-emetics Oral administration likely unreliable
drug of choice is a prokinetic in functional bowel obstruction (not recommended in complete mechanical bowel obstruction)
Cyclizine ± haloperidol or levomepromazine
2.Reducing GI secretions
Anticholinergics – hyoscine butylbromide
OR/AND
Octreotide
- Reducing bowel wall oedema
Dexamethasone 8 mg SC before midday
Evidence is equivocal – consider a 3 day trial - Reducing colic
Strong opioid (likely required for background pain)
Hyoscine butylbromide
What should be considered before surgery in the bowel obstructed patient?
Is the patient likely to benefit?
Surgery will only benefit selected patients with mechanical obstruction.
Is it technically feasible?
In advanced cancer…
Operative mortality (death within 30 days of operation) of 9–40%
Complication rates 9–90%
What surgical procedures are available?
Self-expanding metallic stents
(In recent years stents have been used increasingly in the management of obstructions in the gastric outlet, proximal small bowel and colon.)
Nasogastric suction
A NGT can be used temporarily to reduce a large volune of secretions before the start of pharmacological treatment and during the first few days of treatment.
Long term use of a NGT should only be considered if drug therapy ineffective and a gastrostomy cannot be performed.
What are the take home points?
- Using a targeted approach for nausea and vomiting, matching anti-emetic to likely cause
- Always prescribe laxatives with opioids
- Generally use a stimulant and softener laxative combination
- Always consider whether investigations and treatments are appropriate to the individual patient
- Continually reassess and re-evaluate, ask for help!