Diver Safety Series
By Dr. Naomi Ross - UCBC Safety Advisor
Vomiting underwater is a serious issue as it has been found to initiate or complicate 10% of Diver Fatalities.
Vomiting can be divided into three stages:
there is increased salivation, and the stomach relaxes while the small intestine contracts, meaning the contents of the small intestine are forced into the stomach.
the glottis consists of the vocal cords and the slit between them. The glottis closes over the opening from the throat into the lungs. This is to protect the person from breathing the vomit (aspiration). This also means that no air can enter or be released from the lungs.
the lower esophageal sphincter (a valve between the esophagus and stomach) is normally closed to prevent stomach contents from going into the esophagus. In the puking stage, the sphincter relaxes and the bottom part of the stomach contracts, meaning stomach contents are pushed up the esophagus and out through the mouth.
Vomiting underwater is particularly dangerous for two reasons:
1. When a person is retching or vomiting, the glottis is preventing air from being released from the lungs, meaning there are the same risks to the diver as holding breath if he starts to ascend: pulmonary barotrauma or arterial gas embolism.
2. A vomiting person is not breathing, and there is a reflex to take a large breath after vomiting. Under water, this presents obvious risks.
While there are many causes for nausea and vomiting, the most common while diving are seasickness and salt water aspiration. Salt water aspiration usually occurs while surface swimming or snorkeling. It can also come from a leaking exhaust valve in the second stage of the regulator.
The best thing to do for vomiting underwater, is to avoid it.
If you don’t feel well, cancel the dive.
If you were well enough when you went into the water, but become nauseous while down there, attempt to safely ascend.
However, once you start retching, stop ascending to avoid pulmonary barotrauma.
Once vomiting starts, there are two choices:
1. Vomit through the regulator.
This is the best choice if the stomach contents are well-digested (last meal was a few hours ago, or the food was well-chewed). This prevents aspiration at the time of the reflex deep breath post-vomiting. However, there is potential for larger food chunks to get caught in the second stage of the regulator. This means that if your buddy isn’t right there to help you, you need to grasp for your octopus during, or immediately after vomiting.
2. Remove the regulator from your mouth.
The danger is taking the reflex deep breath before having a chance to put the regulator back in the mouth and purge it.
After vomiting, consider the dive over.
Profound fatigue can follow the episode. (even though you now have a great photography moment as the fish swarm in to clean up the vomit)
Preventing the vomiting cycle:
- • Keep yourself fit.
- • Drink lots of water before and between diving.
- • Get adequate sleep before the dives (you can do all night parties at home rather than risk compromising your dive trip)
- • Avoid excessive alcohol use (ditto, you can party at home)
- • Eat light meals and avoid spicy food and fatty food. Remember to take extra care to fully chew all the food
- • Stay on deck to breathe fresh air and keep your eyes on the horizon
- • Over-the-counter medications such as Gravol (side effect is drowsiness)
- • Natural products such as ginger
- • Wrist bands: work by putting pressure on an acupuncture spot on the inside of the wrists
- • Scopolamine patches: applied behind the ears. Side effects are dry mouth and blurry vision, and they may not stay on after being in the water
- • Prescription medications such as promethazine (Phenergan) which is not available in Canada or Serc (which is more for the dizziness factor of sea-sickness, but can have gastrointestinal side effects and cause headaches)