Vomiting (aka emesis) is the involuntary, forceful expulsion of stomach's contents, through the mouth, and sometimes the nose. Nausea is the feeling one is about to vomit, but doesn't necessarily result in vomiting. Regurgitation (aka posseting) is return of undigested food back up to the mouth, without the force/displeasure of vomiting. D&V is shorthand for diarrhea and vomiting.
What is vomiting, and how does it differ from nausea?
Vomit is where stuff inside the tummy, involuntarily and forcefully comes out of the mouth. Nausea is where you feel like vomiting.
Gastric secretions, which are highly acidic
Recent food intake
Vomiting is caused by stimulation of receptors in the chemoreceptor trigger zone, on the floor of the 4th ventricle of the brain, known as the area postrema
The area postrema is a circumventricular organ (i.e. structures in the brain charcterized by their extensive vasculature, and lack of normal BBB, allowing for linkage between the CNS and the peripheries), and thus can be stimulated by blood-borne drugs, that can stimulate or inhibit vomiting
There are various inputs to the vomiting center, including:
Stimulation of different receptors in the chemoreceptor trigger zone (e.g. dopamine D2 receptors, serotonin 5-HT3 receptors, opioid receptors, acetylcholine receptors, substance P), in different pathways, in which the final common pathway involves substance P
Vestibular system, sends information to the brain via CN8 (vestibulocochlear), which plays a major role in motion sickness, and is rich in muscarinic and histamine H1 receptors
CN10 (vagus) is activated when the pharynx is irritated, causing a gag reflex
Vagal and enteric nervous system inputs information regarding the state of the GI system. Irritation of the GI mucosa by chemotherapy, radiation, distension, or acute infectious gastroenteritis activates 5-HT3 receptors of these inputs
CNS mediates vomiting that arises from psychiatric disorders and stress from higher brain centers
GERD (gastroesophageal reflux disease)
Food allergies (often also causing hives/swelling), including allergic reaction to cow's imlk protein (milk allergy, lactose intolerance)
What can cause vomiting?
It can be a problem with the tummy system. So for example, an infection. Eating something dodgy. Reflux. An obstruction. Eating too much . An allergy. It can also be infection of one of the tummy organs, say the liver, gallbladder, pancreas, or appendix. The cause can also be somewhere in the brain, such as brain cancer.
Fresh blood, called hematemesis, is vomit that is bright red, and suggests bleeding from the esophagus
Dark red vomit with liver-like clots, suggests profuse bleeding in the stomach, e.g. from a perforated ulcer
Coffee ground vomiting, where there is altered blood resembling coffee grounds, as the iron in the blood is oxidized. This suggests bleeding in the stomach, because the gastric acid has had time to change the composition of the blood
Bile, is vomit that is green or yellow, which can enter vomit during subsequent heaves due to duodenal contraction if the vomiting is severe. It indicates the pyloric valve is open, and bile is flowing into the stomach from the duodenum. Sometimes, gastric contents can have a yellow tinge, which is not bile. It can indicate:
Mechanical bowel obstruction
Fecal vomiting (aka stercoraceous vomiting, copremesis) is vomiting, in which partially or fully digested matter is expelled from the intestines, into the stomach. It is often a consequence of intestinal obstruction or a gastrocolic fistula. Though it is not usually fecal matter that is expelled, it smells noxious
Dry heaves (non-productive emesis) is where the vomiting reflex continues for an extended period with NO appreciable vomitus. It can be painful and debilitating
Projectile vomiting is vomiting that ejects the gastric contents w/ great force. It is a classic Sx of infantile hypertrophic pyloric stenosis, in which it typically follows feeding and can be so forceful that some materials exits through the nose
Are there different types of vomit, or is vomit just vomit?
You can differentiate it based on its contents, and the color of vomit. These things are sort of related. So there can be blood, which can be fresh or coffee ground colored. Bile. Fecal content. Color, can be bright red, dark red, or coffee ground, with the bleed going further down the tract as the color goes darker, and more digestion of blood has occurred. Yellow suggests bile.
Antiemetics to suppress nausea/vomiting
Where dehydration results, rehydration/IV fluids
What can you do for someone who's vomiting?
You can give anti-vomiting drugs, a popular one being ondansetron. Because vomiting can also cause dehydration, you may need to give fluids.
Aspiration of vomit
Dehydration and electrolyte imbalance, as prolonged and excessive vomiting depletes the body of water, and alters electrolyte status
Gastric vomiting directly causes loss of acid (H+) and chloride (Cl-) directly. Alkaline tide is where normally after eating a meal, the stomach's parietal cells will produce bicarbonate ions (alongside HCl), which is basic, thereby increasing blood pH. This causes hypocholeremic metabolic alkalosis (i.e. low Cl, basic pH, high bicarbonate). This causes the kidney to try compensate for alkalosis (too much +) by excreting more potassium, causing hypokalemia
If vomiting of intestinal contents occurs, which is less frequent, this will include bile acids and bicarbonate, and can cause metabolic ACIDOSIS
Cachexia, if the Pt loses intake of food
What bad things can happen as a result of vomiting?
The vomit can come up, and you can breathe it in. That can cause a chest infection. You can also lose fluid that way, and it can disrupt the electrolyte balance of your body. It can cause a tear of that part where your stomach, and the tube just above connects to it, because of the refluxing acid. And it can ruin your teeth, because of the acidic contents of the tumy.