A diver visited my office recently because she was having difficulty equalizing her ears. She had a history of hayfever, often had nasal congestion and occasionally used antihistamines. She had difficulty clearing on all of her diving vacations. Another trip was coming up and she was seeking advice on how to prevent ear squeeze. Upon examining her, I found her allergies caused complete blockage of her nasal airways and Eustachian tubes.
Ear problems occur during descent because of Boyle's Law, which dictates that the volume of the air space in the middle ear will shrink as pressure increases unless equalization occurs through the Eustachian tube (or through a perforated ear- drum). The middle ear is the air filled space behind the drum. It contains the small bones that transmit sound to the cochlea, where there are specialized nerve cells that convert vibrations into the sensation of sound. The Eustachian tube, which connects the middle ear to the throat, provides pressure equalization (see the diagram).
Ear squeeze or middle ear barotrauma occurs when the middle ear cannot be equalized with ambient pressure. Squeeze is always accompanied by pain, which should be a signal to stop your descent and equalize. Squeeze causes injury to the eardrum and when severe, causes hemorrhage into the middle ear and rupture of the eardrum. Difficulty clearing or equalizing the ears is a problem every diver has experienced. Inability to equalize occurs when you cannot open the Eustachian tube to allow air to enter the middle ear and balance the pressure across the eardrum (see the ear diagram). If you have constant trouble equalizing, have evaluation by an ear and nose specialist to find out why.
ROUND WINDOW RUPTURE
Round window rupture (RWR) is a serious barotrauma injury caused by trying to equalize forcefully during descent. The Valsalva maneuver is performed by pinching the nose and bearing down gently to increase the pressure in the mouth and nasal passages. If the Eustachian tube is blocked, the middle ear pressure will be below ambient and the large pressure difference can tear the round window (see diagram). When the round window tears, fluid from the inner ear leaks into the middle ear, hearing is lost, vertigo occurs and hissing or buzzing is heard constantly. The tear in the round window may heal itself but surgery is often needed. If repair is incomplete, permanent partial hearing loss is likely and diving is no longer recommended.
If your ears do not equalize and your eardrum ruptures, cold water will enter through the perforation, upset the balance mechanism and cause sudden vertigo, dizziness or even vomiting. Diving must be avoided for several weeks after a perforation. If you rupture an eardrum while diving, you should see a physician, get treatment to prevent ear infection and wait for healing to occur. You may be unable to dive for three to four weeks but with proper care, the drum will heal. After an examination by your doctor, you should be able to dive again.
Chronic eardrum perforations usually occur when there is poor Eustachian tube function owing to allergy or chronic sinus infection. Individuals who have a permanent eardrum perforation need a consultation with an ear, nose and throat specialist.
Water entering the middle ear from a perforated eardrum can result in a middle ear infection, permanent perforation of the drum and reduced hearing. If you get a middle ear infection, you will need antibiotics and a decongestant for a week or more.
PREVENTING EAR BAROTRAUMA
With proper care, you can avoid ear squeeze. Practice doing a gentle Valsalva maneuver at home to test your ability to equalize the middle ear. If your Eustachian tubes are working properly, you will hear a soft squeak or the sound of air rushing into both middle ears.
If you cannot "pop" your ears with this simple exercise, then you will have difficulty when diving. A pseudoephedrine (Sudafed) tablet taken an hour before diving or an antihistamine may help reduce swelling in the nose. A saline nasal spray also shrinks the swollen membranes and helps wash out the secretions. For severe allergies with swollen nasal membranes, antihistamines and a steroid nasal spray are often effective.
To avoid ear squeeze, be sure there is no congestion in your nose or throat when you dive. Begin clearing your ears on the surface before you descend and continue to clear every foot or two. Descend feet first to prevent changes in the throat that will block the Eustachian tubes when you head is down. Waiting for ear pain to occur before you try to equalize is a bad habit. You cannot usually clear a blocked ear at this stage. You must ascend three or four feet, equalize, then try another descent. If you still have trouble after using the correct method of clearing, have an ear, nose and throat exam by a doctor who knows diving medicine.
When U/W, all the tissues of the body are subjected to the increased pressure. The ears can detect the minuscule pressure changes caused by sound and are easily injured by large pressure changes. You are likely to experience ear problems sometime during your lifetime. Protecting your ears during diving requires careful attention to the health of your nose and throat and to your technique for equalizing your ears. You can find more on diving medicine on our Web site: www.scubamed.com.