Nausea is associated with general malaise, a tightness in the throat and a feeling of imminent vomiting. It is normally accompanied by sweat, paleness, tachycardia, a sense of weakness and vertigo. Nausea generally precedes vomiting (with an important exception represented by brain tumors); nausea can also occur in the absence of vomiting. In many cases, vomiting reduces the feeling of nausea. From a teleological point of view, nausea has a "motivation", as it prevents food intake in some situations, where the introduction of food is not indicated (for example during gastro-intestinal infection). Given, however, that nausea and vomiting may appear (directly or indirectly) even in the course of various diseases affecting different organs, often these "motivations" are not particularly evident.
If you are reading this article because you only care about the excessive salivation, we refer you to the following link >> salivation. This rare symptom may be caused by gastrointestinal diseases, especially in the mouth. It can accompany some systemic diseases and can result from the effects of drugs and toxins. There may also be an accumulation of saliva due to difficulty swallowing.
Center of vomit.
The so-called center of vomit, at the level of the encephalic trunk, is composed of two areas: one is called the center of vomit, and is located in lateral reticular formation, immediately close to the centers that govern the associated activities, such as salivation and respiration; the other, which is called the chemo-regulation zone, is located in the fourth ventricle floor. The center of the vomit is activated by impulses coming from the gastro-intestinal canal and other peripheral structures, while the toxic agents that are found in the blood circulation and the impulses that come from the cerebellum stimulate the chemotherapeutic regulation zone; this in turn sends impulses to the center of the vomit. Before the threshold of vomit is overcome, impulses are sent to the cerebral cortex, which gives rise to the feeling of nausea.
Just before vomiting increases the secretion of saliva; this is because the regulator center of saliva is close to that of vomit; the contraction of the intercostal muscles and the diaphragm produces a rapid inhalation and an increase in intra-abdominal pressure; this action is favored by the contraction of the abdominal muscles; at the same time the pylorus is contracted while the fundus and the cardias are released. In this way the gastric contents are expelled. In unconscious patients, the closure of the glottis protects the lungs from a possible aspiration. The nausea caused by stimulation of the vestibular receptors is mediated by the movements of the muscles of the head, neck and eyes; the presence of a vertical component of the movement is not necessary. This explains why motion sickness can occur in individuals who are sitting "in reverse" or with their backs to the direction of movement. On the other hand, a vertical component of the movement worsens the feeling of nausea and you are directly responsible for it, for example when an elevator stops abruptly. Probably in this case the nausea is mediated by the vagus nerve.
Almost all diseases of the gastro-intestinal tract can cause vomiting,
as well as many diseases of other organs (usually associated with pain), and
some functional disorders. The following causes provide some examples.
These include oesophageal transit obstructions (eg tumors, diverticula,
achalasia), gastric transit (eg gastric cancer), or intestinal transit (eg
invagination, volvulus, tumor), inflammatory processes such as gastritis acute,
pancreatitis or cholecystitis.
Urememia, hepatic coma and diabetic ketoacidosis are metabolic disorders that
most often cause vomiting. In the course of endocrinological crises (such as in
cases of hyperthyroidism, Addison's disease, hyperparathyroidism or
hypoparathyroidism) vomiting is probably caused by toxins.
The center of the vomit can be directly stimulated (for example through morphine,
apomorphine, digital or chemotherapies); it is also possible to be stimulated by
an irritation of the gastro-intestinal mucosa (for example by salicylates).
A fundamental role is played by emotional reactions, disgust, pain, shock and
sepsis, as well as by the increase in intracranial pressure, which occurs in
some brain tumors.
The vomit itself does not offer any clues about the underlying disease that
triggered it, so it is important to investigate the temporal characteristics,
the appearance and the accompanying symptoms.
Morning vomit (abundant) is suggestive of a cause of central nervous origin; however, it can also occur during pregnancy (rarely), in
metabolic disorders or
alcoholism. The vomiting that arises far from the meal is suggestive of
an
obstruction to food transit (for example stenoses that reduce gastric emptying
or diabetic gastroparesis); if, on the contrary, vomit appears shortly after
eating, the pseudo-peptic ulcer or the psychoneurotic genesis must be considered
among the most probable causes.
The following symptoms provide other indications on the causes of the onset of
vomiting:
• nausea: usually precedes vomiting. Its absence may be indicative of a central
nervous cause;
• fever: a typical symptom of an acute infectious disease. In the case of
appendicitis, the temperature is generally high. However, fever is not a
mandatory symptom;
• diarrhea: typical of a gastroenteritis, although it may also occur during
uremia;
• headache: the unilateral headache, intense and accompanied by vomiting, is
suggestive of a migraine. The generalized headache with signs of me-ningism
suggests a meningitis or even a symptom of accompanying an epileptic seizure;
• abdominal pain: epigastric pain is suggestive of a gastric disease,
pancreatitis or biliary calculosis; umbilical pain india a pathological process
at the level of the small intestine or colon; the pain in the side can be caused
by a colic;
• chest pain: localized in the retrosternal region causes a myocardial
infarction to be suspected; if it changes with the breath acts and is
accompanied by dyspnea it is possible that it depends on a pulmonary embolism.
-The smell of vomit is typically acidic when it comes from the stomach.
Evidence-nothing regurgitation from an esophageal diverticulum or secondary to
achalasia does not have the same odor. A faecal odor suggests an intestinal
occlusion.
In Zollinger-Ellison syndrome or in duodenal ulcer, vomiting is almost
exclusively made up of large quantities of gastric secretions. During pregnancy
or chronic gastritis, vomiting usually consists of modest amounts of mucus.
The site of hemorrhage is usually proximal to the corner of Treitz. The coffee
aspect is due to the action of gastric juice on the blood. This leads us to make
two considerations:
• bright red blood suggests that there has been no contact with the hydrochloric
acid in the stomach;
• the blood of a pink color (coffee grounds) indicates that it has been digested
by hydrochloric acid and, therefore, remained in the gastric cavity for some
time.
If vomiting has an acute presentation, it is advisable to investigate metabolic, pharmacological, infectious or toxic causes; this is possible through medical history, physical examination and laboratory investigations. If vomiting appears frequently or is chronic, an endoscopy or gastro-intestinal transit study is indicated to identify or rule out a mechanical obstruction. When a mechanical stenosis is detected, the procedures and therapies vary according to the type of obstruction and its location; after excluding the hypothesis of a mechanical stenosis, the possible causes may be neurological, endocrinological) or psychic; in this case a consultation with the specialist in the branch will be necessary.
indice argomenti di gastroenterologia