Vomiting and regurgitation Flashcards
List differencces between regurgitaiton and vomiting
Clinical sign
Regurgitation
Vomiting
Nausea or salivation
No
Common
Retching (abdominal contractions)
No
Common
Presence of bile
Rare
+/-
Cervical oesophageal distension
+/-
No
Amount of material
Any
Any
Time after eating
Variable
Variable
pH (poor indicator)
Variable – usually neutral high
Variable – usually low pH
Prodromal signs (salivation/lip smacking)
sometimes
often
Material expelled when head lowered
Typically
Explain the pathophysiology of regurgitation
- Dogs: the oesophageal body is completely striated muscles
- Cats: distal 1/3 to ½ of oesophagus is smooth muscle
- In both species during swallowing the upper oesophageal sphincter relaxes to allow passage of food or liquid into the proximal oesophagus
- A primary peristaltic wave is moved distally to the stomach.
- Secondary peristaltic waves are generated in response to intraluminal distension to clear remaining material.
- Lower esophageal sphincter relaxes as food approaches as passes into somach.
- Diseases resulting in inflammation, obstruction, or hypomotility in oesophagus interrupt the normal process causing regurgitation.
Explain the differentials and diagnosis of regurgitation
Explain vomiting
- Active expulsion of ingesta from stomach and sometimes duodenum through the mouth.
- Vomiting involves centrally mediated reflex with coordinated closure of the nasopharynx and glottis to protect the airway reducing risk of aspiration pneumonia
- Vomiting evolved to protectagainst ingestion oftoxic or noxious substances which explaines activating neural and humoral stimli
Explain the pathophysiology of vomiting
- Initiated by emetic center composed of nuclei in medulla oblongata in the brainstem.
- Neurokinergic (NK1) receptors located in the adjacent nucleus tractus solitary (NTS) -> stimulates the emetic center.
- Activation of receptors may occur indirectly by humoral pathways via chemoreceptor trigger zone (CRTZ) or directly through neural pathways from the GI tract, cerebral cortex, or vestibular system.
Complete the diargram
Where is the Central trigger zone located? How does it sample blood
CRTZ located in area postrema in fourth ventricle floor lacks BBB -> allowing sampling of chemical stimuli in the blood.
What receptors does the central trigger zone have?
CRTZ has dopimanergic (D2), histaminergic (H1), adrenergic (alpha2), serotonergic (5HT3), cholinergic (M1), enkephalinergic (ENK ), and neurokinergic (NK1) receptors.
Why doesnt apomorphine work in cats?
- Apomorphine (D2 and D2 agonists) is potent stimulator of emesis in dogs but has little to no effect in cats, suggesting lack of D2 receptors in species.
- Xylazine is effective emetic in cats suggesting that alpha2 receptors may be important
What pathways are involved in neural stimulation of vomiting?
- Neural stimulation occurs via afferent vagal, sympathetic, vestibular, and cerebrocortical pathways.
How does GIT disease stimulate vomiting?
- GIT disease directly causes vomiting by stimulating release of serotonin from enterochromaffin cells that bind 5HT3 receptors on afferent vagus nerves (dog or the CRTZ (cat)
What is the appropriate clinical approach to a vomiting patient?
Description of vomiting episodes to differentiate from coughing or regurgitation
- frequency, duration, relation to eating or drinking, and vomitus
- >8hrs after ingestion-> suggests delayed gastric emptying due to gastric outflow obstruction or hypomotility
- bile suggests patency of gastric outflow tract
- Fresh or digested blood indicates GI erosions or ulcers
- Acute or chronic (>1-2 weeks) or sporadic (intermittent acute)
Dietary history
- Past, and current diets
- Changes or opening a new bag, or can of food
- Medication: drugs, supplements, nutraceuticals, and alternative herapies
- Exposure to toxin or foreign body
- Vaccination status, travel history, exposure to other animals
Physical exam
- Patient demeanor
-
Oral exam
- ulcers associates with uremia or toxins
- lingual linear foreign body
- icteric MM -> liver disease
- Cardiac arrhythmia -> metabolic derangements or toxin ingestion
-
Abdomen palpation for
- Pain -> pancreatitis, obstruction
- Effusion -> peritonitis
- Gas distension -> obstruction, gastric dilation-volvulus,
- Organomegaly
- Rectal exam -> melena, constipation, or foreign body material
Outline your diagnostic approach to acute vomiting?
Outline your diagnostic approach to chronic vomiting
List the metabolic disease causes of vomiting?
Metabolic disease
Renal disease
Hepatobiliary disease or failure
Electrolyte derangements
Endotoxaemia
