Causes of Vomiting and Nausea?
GI pathology: DA/5HT - motility - bowel obstruction - infection (gastroenteritis) - external pressure on stomach - liver mets CTZ pathology: DA/5HT - meds (opioids, chemo, Abx, digoxin, NSAIDs - metabolic (urea, Ca, Na+, - toxins - organ failure Vestibular: DA/ACh/5HT - motion - cerebellar Neurological - ICP - cerebellar Psychiatry - pain - anxiety
Go through some treatments for Nausea/Vomiting
Metoclopramide - D2 antagonist - prokinetic (cholinergic) - crosses BBB so gut/CNS - prolonged use tardive dyskinesia, EPSE, anti-dopamine effects (rigidity) Domperidone - D2 antagonist - safe for use in Parkinson's - doesn't cross BBB - EPSE, dry mouth - gastric stasis Haloperidol - antipsychotic and D2 - bowel obstruction (no prokinetic effect) Cyclizine - antihistimine and antimuscarinic (ACh) - motion sickness, raised ICP, mechanical - vestibular site of action Promethazine - antihistimine - pregnancy/vestibular - sedating with anti-SLUD Ondansetron - 5HT3 antagonist on CNS - post- chemo and post radiotherapy Hyoscine - antimuscarinic - hydrobromide crosses BBB - butylbromide (buscopan) doesn't cross BBB - bowel obstruction
A person comes in with a GIT cause for N/V, what treatment would you consider giving?
- metoclopramide (not in bowel obstruction but useful in constipation) - domperidone - cisapride (specialist) - motility stimulant may also need treatment for NSAID/hyperacid - PPI - ranitidine
A person has a CTZ induced N/V?
- haloperidol - metoclopramide - prochlorperazine (frequently given)
Immediate chemo-induced N/V treatment?
- dexamethasone (decreases sleep disturbance if given in the morning) - stop if no benefit after 5 days - chemo/radiotherapy - ondansetron
- Prochlorperazine - haloperidol - levomepromazine (multiple receptors, D2, histamine, muscarinic and 5HT2)
prophylaxis in the form of dexamethasone and avoid volatile anaesthetics.
Outline the physiology of vomiting
brainstem vomiting centre in the medulla oblingata gets multiple inputs: - CTZ (also in medulla) has DA and 5HT3 receptors - vestibular (motion sickness) has histimine and muscarinic receptors - higher brain - vagal sensory nerve fibres (certain foods) all these things can stimulate the emetic reflex
How to treat someone acutely with mechanical obstruction?
- NBM - NGT - IV fluids - analgesia - +/- surgery
How to treat someone with subacute bowel obstruction?
- partial (oral is okay) - maxalon (metoclopramide) - complete (Dx - sounds, distended, tender, vomit with fecal matter, time after fluid intake) DO NOT USE PROKINETIC - can cause perforation if complete bowel obstruction - neutral - haloperidol - cyclizine - buscopan (accept death) consider dexamethasone - reduces swelling. ranitidine - dry out secretions.
Summarise anti-nausea agents
ondansetron - 5HT3 (CTZ), only for cancer, SE of constipation domperidone (no BBB -good for PD), metoclopramide (prokinetic) haloperidol (CTZ)- D2 cyclizine (vestibular) - antihistamine buscopan - muscarinic dexamethasone - raised ICP (reduce swell)
What is your management for someone presenting with first episode constipation?
Avoid precipitation by: - using toilet regularly - ensure hydration - optimising fibre - control other symptoms Prophylaxis is essential. Bulk-forming laxatives have no role in non-ambulant patients (i.e. psyllium, sterculia). A combo of stool softener and stimulant laxitive is best: - docusate + senna Classification: Stool softener - docusate, glycerol Osmotic - macrogol (powder), lactulose Stimulant - senna, bisacodyl, methylnaltrexone (for opioid only) Lubricant - glycerol and olive olive
89 year old, bed bound, poor oral intake, become incontinent of liquid faeces. Abdominal XRay shows colonic faecal loading. What is the best management? a) fibre b) lactulose c) glyceryl enema d) manual disimpaction e) coloxyl and senna
glyceryl enema For faecal impaction (confirmed with rectal examination) - Use high dose oral movicol and rectal therapy (enemas) - Glycerol suppository and if ineffective osmotic enema (microlax)
What is the stepwise approach to laxative therapy?
- Use bulk forming initially (psyllium (metamucil) or sterculia (normafibe)) - Ineffective use osmotic (movicol or osmolax) - If ineffective use a stimulant (docusate + senna or bisacodyl) - Ineffective use pricalopride (prokinetic 5HT4 specific - few SE)
List some causes of increased output from a stoma?
1) infection 2) malabsorption 3) ischaemic colitis (look for lactate) 4) medication 5) radiotherapy colitis 6) inflammatory colitis (faecal calprotectin) 7) fistula 8) bacterial overgrowth 9) thyroid 10) pancreatic insufficiency (faecal elastase) 11) prokinetic (trial cholestyramine)
Go through the constipation pyramid
Step 1 in non-drug caused, acute start 5/6. 1) Lifestyle 2-4weeks before laxatives - exercise - fluid intake - fibre in diet 2) Bulk-forming laxatives - Isphagula husk (fybrogel) - psylium (metamucil) - low molecular hydrocolloids dissolve in water 3) Stool softeners - docusate (coloxyl) 4) Osmotic laxatives - lactulose or sorbitol (e.g. movicol) - magnesium sulphate 5) Stimulants - sennosides or bicasodyl 6) Suppository enema - glycerin suppository (onset in 30mins) - warm water enema (onset immediate) 7) colonic lavage
Causes of Constipation?
Drugs: 1) opiates - step 5 regular dosing (stimulants) - Step 3 for low dose 2) anticholinergics (antidepressants, antipsychotics, antihistamines) - step 1 3) Resins - cholestyramine 4) Diuretics Others - iron/verapamil Physiological: - dehydration - starvation Psychological - avoidance - depression Mechanical: - diverticula - carcinoma - neurological
20 year old in for pilonidal abscess drainage. Nursing staff are worried hes acting strange. Given paracetamol and an anti-emetic 10mins previously. His eyes are deviated upwards and his pupils are dilated. What do you do?
IV procyclidine (anticholinergic)
- this is an oculogyric crisis (acute dystonic reaction) mainly seen with neuroleptics and with the anti-emetic metoclopramide.
- fixed stare, followed by
- maximally upward deviation of eyes which converge or deviate
- backwards and lateral flexion of the neck, widely open mouth, tongue protrusion
- ocular pain
- onset may be paroxysmal over hours or acute.