9 - Nausea & Vomiting Flashcards
What is retching?
Strong, involuntary and unsuccessful effort to vomit
What is the area of the brain that coordinates vomiting and what does it do?
- Vomiting center
- Receives and integrates afferent impulses and stimuli and then sends efferent impulses to salivation centre, respiratory centre, pharyngeal, GI, and abdominal muscles
What are the NTs and receptors involved in vomiting?
- Dopamine
- Histamine
- Acetylcholine
- Vasopressin
- Serotonin
What is important pathophysiology for motion sickness?
Vestibular function disturbances
What is mismatched vestibular function?
When what the body is expecting and what the body actually feels don’t match up
What are some causes of nausea and vomiting?
- Visceral afferent stimulation (mechanical obstruction, motility disorders, peritoneal irritation, infections)
- CNS disorders (increased intracranial pressure, infections, psychogenic)
- Irritation of chemoreceptor trigger zone (initiated or withdrawn drugs, systemic disorders)
What are some complications of vomiting?
- Dehydration
- Aspiration
- Malnutrition
- Electrolyte or acid-base imbalance
- Dental caries
- Esophageal rupture
What are signs and symptoms of dehydration in adults?
- Increased thirst
- Decreased urination
- Feeling weak or light-headed
- Dry mouth/tongue
What are signs and symptoms of dehydration in children?
- Dry mouth and tongue
- Decreased urine output
- Dark urine
- Increased heartbeat
- Decreased skin turgor (when pinched, skin returns to normal very slowly)
- Weight loss
What are the 2 classifications of nausea and vomiting and what are symptoms of each?
1) Simple
- Occasional episodes
- Self-limiting or relieved by minimal use of anti-emetic
- Not related to administration/exposure to noxious agent
2) Complex
- Symptoms not adequately or readily relieved by single anti-emetic
- Consequences severe
- Caused by noxious agents or psychogenic events
When is the greatest incidence of motion sickness?
3-12 years old (under 2 are immune)
What are risk factors for motion sickness?
- Type of travel (boat worst and train least)
- Stimulus intensity and frequency
- Duration of directional change
- Poor ventilation
- Individual predisposition
What are the goals of therapy for nausea and vomiting?
- Eliminate or decrease symptoms of nausea
- Prevent or decrease frequency of vomiting
- Prevent complications of nausea and vomiting
What is the mechanism of action of dimenhydrinate and diphenhydramine?
- Blocks ACH and H1 receptors centrally
- Acts on H1 receptors in vomiting centre
What is the dosing of dimenhydrinate for treatment of motion sickness in adults?
50-100 mg every 4 hours if necessary to a maximum of 400 mg per day
What are side effects to dimenhydrinate and diphenhydramine?
- Sedation, blurred vision
- Dry mouth
- Constipation, urinary retention
- Paradoxical excitation in children
What is the mechanism of action of scopolamine?
Blocks ACh in vestibular apparatus
What is scopolamine used for?
Prevention of motion sickness
What is the dosing for scopolamine?
- Apply 1 patch to dry hairless area of post-auricular skin
- Should be applied 4-12 hours before departure
- Disc should not be left on more than 72 hours and can reapply to other eye
- Treatment should not exceed 6 days
Is scopolamine recommended in children?
No
Is ginger recommended in children?
Only over 12 years old
What are side effects to scopolamine?
- Sedation, dizziness, blurred vision
- Constipation
- Rash
- Elderly at increased risk of CNS effects
What is the dosing for ginger root?
- Prevention – 2 tablets/lozenges 30 minutes before departure
- Treatment – 2 tablets/lozenges 1-3 times per day (do not exceed 6 per day)
What is a side effect to ginger root?
Can exacerbate symptoms in patients w/ acute inflammatory skin diseases and can cause contact dermatitis
What are contraindications for dimenhydrinate, diphenhydramine, and scopolamine?
Use under Dr. supervision if px has:
- Seizure disorder
- Respiratory condition (COPD, asthma)
- Difficulty w/ urination from BPH
- Narrow angle glaucoma
- Obstructive bowel disease
What is the best treatment for motion sickness for children aged 2-12?
Dimenhydrinate or diphenhydramine
Should breastfeeding women use pharm treatment for motion sickness?
No
Can pregnant women use pharm treatment for motion sickness?
Can use gravol, ginger root or promethazine under doctor supervision
What is the dosing of diphenhydramine for patients 12 years and over?
25-50 mg 3-4 times per day (maximum 4 doses per day)
When is promethazine used?
- Treatment and prevention of motion sickness
- Usually used if patient has refractory nausea or if DMH is ineffective
What is the dosing of promethazine for adults?
25 mg with first dose 30 minutes before departure and second dose 8-12 hours later if needed
What is the dosing of promethazine for children?
0.5 mg/kg (max. 25 mg) w/ first dose 30-60 minutes before departure and second dose 12 hours later if needed
What drugs dose promethazine interact with?
CNS depressants and alcohol
What is a contraindication for promethazine?
Lower respiratory tract symptoms
What are side effects to promethazine?
- Sedation, somnolence
- Dry mouth
- Extrapyramidal symptoms
- Constipation
What are some non-pharms for motion sickness?
- Avoid or decrease exposure to precipitating factors
- Avoid eating large meals w/in 3 hours of travel
- Avoid smoking, alcohol and disagreeable odours
- Improve ventilation
- Avoid visual stimuli
- While travelling, focus on stable external object or the horizon
- While on a boat, stay in a central location least susceptible to motion
- While in a vehicle, sit in front seat w/ clear forward view and minimize head movement
What is the endpoint of therapy for nausea and vomiting?
Minimal or no nausea and no vomiting
What should be done if the endpoint of therapy isn’t reached?
- Increase dose
- Make sure dose is taken 30-60 minutes before departure
- Refer
What should be done if patient experiences intolerable symptoms from treatment?
- Decrease dose
- Switch products
- Rely on non-pharms alone
What are some red flags for adults?
- Fever and/or diarrhea
- Suspected food poisoning that is severe and doesn’t clear up in 12 hours
- Severe abdominal pain
- Lasting more than 3 days
- Severely dehydrated
- Blood in vomit
- Significant weight loss
- Pregnant or breastfeeding
What are some red flags for children?
- Younger than 2 years old
- Signs of dehydration
- Vomiting lasting longer than 6 hours
- Lack of urination in past 8-12 hours
- Stiff neck
- Weight loss
- Vomit is red, black, or green
- Vomiting after each meal
- Poisoning or head trauma suspected
