Squeeze during descent occurs when gas in a cavity is compressed. The
types of squeeze most frequently encountered in diving are:
-
Middle ear squeeze is the most common form of barotrauma, caused by a
blocked or dysfunctional eustachian tube or from improper equalization. This
will cause immediate pain—which becomes progressively worse as the
eardrum stretches—and possibly vertigo, hearing loss, and tinnitus. If descent
is continued without equalizing the pressure, the eardrum may eventually
rupture. If this occurs the pain will immediately disappear, but nausea and
vertigo may result from cold water entering the middle ear.
-
External ear squeeze is caused by a hood or other piece of equipment covering
the external ear passage. This may result in the same symptoms as a middleear
squeeze.
-
Sinus squeeze is caused by blocked passages that vent the sinuses to the upper
respiratory air passages.
-
Lung (thoracic) squeeze is caused by compression of air in the lungs to a
volume less than residual volume. This could happen in a breathhold.
-
Whole body squeeze can occur when the air supply in a dry suit fails to balance
water pressure. This could be precipitated by a sudden or unexpected increase
in depth, by malfunctioning or maladjusted supply and exhaust valves, or by
the absence or failure of the safety non-return valve.
-
Face mask squeeze can occur when the diver fails to equalize air in the mask
by nasal exhalation. In a full face mask, malfunctioning air supply or valving
can cause face mask squeeze.
-
Suit squeeze is caused by a pocket of air in a dry suit that becomes trapped
under a fold or fitting and pinches the skin in the fold area.
-
Tooth squeeze is caused by a pocket of air in a filling.
To treat squeeze during descent:
1. Stop descent.
2. If efforts to equalize pressure fail, ascend a few feet.
3. Avoid clearing on ascent.
4. Avoid a forceful Valsalva
5. If further efforts to equalize pressure fail, abort the dive.
6. If the diver reports dizziness, ventilate the diver, abort the dive, and evaluate
the need to send down the standby diver to assist.
7. Report the squeeze to the medical personnel trained in diving medicine for
appropriate treatment.
Reverse squeeze occurs when gas
trapped in a cavity cannot escape as it expands during ascent. To treat reverse
squeeze of the middle ear or sinus during ascent:
1. Stop ascent and, if clearing does not occur spontaneously, descend 2 to 4 feet.
2. Ascend slowly and in stages to allow additional time for equalization.
3. Avoid forceful Valsalva.
4. Evaluate the need to send down the standby diver to assist if difficulty persists.
Vertigo may develop.
5. Upon surfacing, report the problem to the medical personnel trained in diving
medicine for appropriate treatment.
Sinus and ear squeeze are best prevented by not diving with
nasal and sinus congestion. If decongestants must be used, check with medical
personnel trained in diving medicine to obtain medication that will not cause
drowsiness and possibly add to symptoms caused by the narcotic effect of
nitrogen.
Refer to Chapter 3 for more information on the signs and symptoms of the
various types of squeeze.
Divers may occasionally
experience abdominal pain during ascent because of gas expansion in the
stomach or intestines. This condition is caused by gas being generated in the intestines
during a dive, or by swallowing air (aerophagia). These pockets of gas will
usually work their way out of the system through the mouth or anus. If not, distention
will occur.
If the pain begins to pass the stage of mild
discomfort, ascent should be halted and the diver should descend slightly to
relieve the pain. The diver should then attempt to gently burp or release the gas
anally. Overzealous attempts to belch should be avoided as they may result in
swallowing more air. Abdominal pain following fast ascents shall be evaluated by
a Diving Medical Officer
1. Do not dive with an upset stomach or bowel.
2. Avoid eating foods that are likely to produce intestinal gas.
3. Avoid a steep, head-down angle during descent to minimize the amount of air
swallowed.
Simple ear squeeze is discussed in paragraph 19-4.1. More
serious forms of ear barotrauma are rupture of the eardrum or round or oval
window.
Ear squeeze may result in eardrum rupture. When rupture
occurs, this pain will diminish rapidly. If eardrum rupture is suspected, the dive
shall be aborted. Vertigo and/or nausea may occur if water enters the middle ear.
Suspected cases of eardrum rupture shall be referred to medical personnel. Antibiotics
and pain medication taken orally may be required. Never administer
medications directly into the canal of a ruptured eardrum unless done in direct
consultation with an ear, nose, and throat medical specialist.
The round window and oval window are membranes that
separate fluid in the inner ear from the middle ear. Inner ear barotrauma involves
the rupture of one of these membranes and may be associated with the diver who
had difficulty clearing his ears (vigorous Valsalva). However, a rupture may arise
for no apparent reason. Often symptoms of inner ear barotrauma will become
evident on the bottom or after the diver reaches the surface. Symptoms may
include vertigo, hearing loss, or tinnitus. Any hearing loss occurring within 72
hours of a hyperbaric exposure should be evaluated for inner ear barotrauma.
Symptoms of inner ear barotrauma can be confused with symptoms of inner ear
decompression sickness or arterial gas embolism for which recompression therapy is the only appropriate treatment. Symptoms of inner ear barotrauma will not be
relieved or may worsen with recompression. If there’s a possibility that the symptoms
of vertigo, deafness or tinnitus may be due to decompression sickness, or if
other neurological symptoms are present, institute recompression therapy. During
decompression from treatment depth, the diver with suspected inner ear
barotrauma should not be exposed to excessive positive or negative pressure when
breathing oxygen on a built-in breathing system (BIBS) mask. The diver should be
kept in an upright sitting position. After surfacing from treatment, bed rest, head
elevation, and hospitalization are indicated until an audiological workup can be
completed by medical specialists.
Middle ear oxygen absorption syndrome
refers to the negative pressure that may develop in the middle ear following
a long oxygen dive. Gas with a very high percentage of oxygen enters the middle
ear cavity during an oxygen dive. Following the dive, the oxygen is slowly
absorbed by the tissues of the middle ear. If the eustachian tube does not open
spontaneously, a negative pressure relative to ambient may result in the middle ear
cavity. Symptoms are often noted the morning after a long oxygen dive. Middle
ear oxygen absorption syndrome is difficult to avoid but usually does not pose a
significant problem because symptoms are generally minor and easily eliminated.
There may also be fluid (serous otitis media) present in the middle ear as a result
of the differential pressure.
The diver may notice
mild discomfort and hearing loss in one or both ears. There may also be a sense of
pressure and a moist, cracking sensation as a result of fluid in the middle ear.
Equalizing the pressure in
the middle ear using a normal Valsalva maneuver or the diver’s procedure of
choice, such as swallowing or yawning, will usually relieve the symptoms.
Discomfort and hearing loss resolve quickly, but the middle ear fluid is absorbed
more slowly. If symptoms persist, a Diving Medical Technician or Diving
Medical Officer shall be consulted.
