While projectile vomiting may seem like an amusing act when portrayed in the media, it can be frightening and distressing to a person who is experiencing its. Most of us are accustomed to the fact that vomiting is a violent process marked by strong contractions of the gut and abdominal muscles in particular. However, with projectile vomiting the force of the expulsion goes beyond what most of us would expect of vomiting.
What is projectile vomiting?
Projectile vomiting is very forceful vomiting where the vomitus is expelled in a gushing manner. Usually these are short bursts of vomiting where the vomitus can be propelled a significant distance away from the person. This type of vomiting is often sudden and a person may not expect it to occur to this degree.
As with any vomiting, there may be episodes of nausea prior to the actual act of vomiting. However in some people with projectile vomiting, they may be no warning. In other words they may not have experienced nausea or any of the other typical symptoms that signals a person that they are about to vomit. In some of these cases the vomiting starts very suddenly.
Why does projectile vomiting occur?
It is important to understand the process of vomiting. Usually vomiting is elicited when the upper gastrointestinal tract is irritated. The irritation of the walls of the gut then sends signals to the vomiting centre of the brain. From here the vomiting center then sends signals back to the gut and to the muscles of the chest wall, as well as the diaphragm.
In order for vomiting to occur, reverse peristalsis has to be initiated. Peristalsis is the term for the rhythmic contractions of the gut wall whereby food is propelled from the mouth to the bowel. However, in reverse peristalsis the contents of the gut are propelled upwards, rather than downwards, from the bowel to the mouth.
For projectile vomiting to occur these muscle contractions have to be very powerful and the gut alone may be unable to create the pressure needed to expel the contents of the stomach through the mouth and into the environment. Therefore the chest wall muscles and even the diaphragm may have to contract to assist with this process. These powerful muscles can increase the pressure within the abdomen significantly and play a crucial role in projectile vomiting.
Even under normal circumstances where there is no projectile vomiting, these muscles can help to generate significant force. It is important to note that while irritation originating from the gut may elicit vomiting, sometimes the vomit centres of the brain can be stimulated by other factors that may not be linked to the gut. For example certain chemicals and the bloodstream can stimulate the vomiting center and therefore even need to projectile vomiting although there is no actual problem in the guts.
Causes of projectile vomiting
Most of the time projectile vomiting is seen with conditions where there is some type of bloackage within the gut, like gastric outlet obstruction. However, as mentioned vomiting may occur when the vomit centres in the brain or the region known as the chemoreceptor trigger zone (CTZ) is stimulated. Projectile vomiting is more commonly seen in infants rather than in adults but can occur in any age group.
An obstruction within the stomach is among the most common cause of projectile vomiting. This is known as gastric outlet obstruction, where a blockage at the end portion of the stomach prevents food and fluids from exiting the stomach and entering the small intestine. Other causes of delaying in the emptying of the stomach, also known as delayed gastric emptying, may also be the cause of projectile vomiting.
As with the stomach, an obstruction in the bowel may also lead to projectile vomiting. This obstruction may be due to a mass, narrowing of the bowel wall, swelling of the bowel walls, or dysfunction of the muscles in the bowel walls. It is usually when an obstruction occurs in the upper part of the gut, mainly in the duodenum of the small intestine, that vomiting may occur.
Pressure on the brain
Pressure on the brain can also lead to projectile vomiting. This raised intracranial pressure may arise with a host of diseases and disorders. It may also occur with trauma, such as a motor vehicle accident, assault or with a fall. With regards to children and babies, shaken baby syndrome may therefore lead to projectile vomiting.
The stomach’s capacity to stretch may be significant but is nevertheless limited. The space within the stomach may fill to capacity with overeating, and the narrow portion of the stomach known as the pylorus cannot empty the stomach contents fast enough. As a result the gut may need to expel the excess food rapidly and vomiting is one such mechanism that it may utilize.
Toxins and poisons irritating the gut lining can instantly trigger vomiting. This is the body’s way of protecting itself before these harmful substances enter into the bloodstream and lead serious complications, even death. In some instances, some of these toxins of poisons have already absorbed into the bloodstream and may have stimulated the chemoreceptor trigger zone (CTZ). The body then elicits projectile vomiting to ensure that any remaining toxin or poison in the gut is not absorbed into the body. This can also be seen with alcohol poisoning.
Psychogenic causes may also be responsible for projectile vomiting. This may be seen with extreme fear, anger or any other strong emotions, especially after a person has eaten. Sometimes even anxiety about the situation or events that is yet to occur can trigger vomiting. Overall psychogenic causes are an uncommon reason for projectile vomiting.
Although uncommon, projectile vomiting may also occur in kidney diseases. This may arise when the kidney is not functioning optimally. The toxins that are usually excreted by the kidney begin to build up in the body. Vomiting in these cases is usually a late symptom and uncommon.