not hypoxia related. Common symptoms of hyperventilation  include:  The treatment for hyperventilation involves restoring  the proper carbon dioxide level in the body. Breathing  normally is both the best prevention and the best cure  for hyperventilation. In addition to slowing the breathing  rate, breathing into a paper bag or talking aloud helps to  overcome hyperventilation. Recovery is usually rapid once  the breathing rate is returned to normal.  During climbs and descents, the free gas formerly present in  various body cavities expands due to a difference between  the pressure of the air outside the body and that of the air  inside the body. If the escape of the expanded gas is impeded,  pressure builds up within the cavity and pain is experienced.  Trapped gas expansion accounts for ear pain and sinus pain,  as well as a temporary reduction in the ability to hear.  The middle ear is a small cavity located in the bone of the  skull. It is closed off from the external ear canal by the  eardrum. Normally, pressure differences between the middle  ear and the outside world are equalized by a tube leading  from inside each ear to the back of the throat on each side  called the Eustachian tube. These tubes are usually closed but  open during chewing, yawning, or swallowing to equalize  pressure. Even a slight difference between external pressure  and middle ear pressure can cause discomfort.  [Figure 17-2]  During a climb, middle ear air pressure may exceed the  pressure of the air in the external ear canal causing the  eardrum to bulge outward. Pilots become aware of this  pressure change when they experience alternate sensations  of “fullness” and “clearing.” During descent, the reverse  happens. While the pressure of the air in the external ear  canal increases, the middle ear cavity, which equalized with  the lower pressure at altitude, is at lower pressure than the  external ear canal. This results in the higher outside pressure  causing the eardrum to bulge inward.  This condition can be more difficult to relieve due to the  fact that the partial vacuum tends to constrict the walls of  the Eustachian tube. To remedy this often painful condition,  which also causes a temporary reduction in hearing  Sinus block can be avoided by not flying with an upper  respiratory infection or nasal allergic condition. Adequate  protection is usually not provided by decongestant sprays  or drops to reduce congestion around the sinus openings.  Oral decongestants have side effects that can impair pilot  performance. If a sinus block does not clear shortly after  landing, a physician should be consulted.  In a similar way, air pressure in the sinuses equalizes with  the pressure in the flight deck through small openings  that connect the sinuses to the nasal passages. An upper  respiratory infection, such as a cold or sinusitis, or a nasal  allergic condition can produce enough congestion around an  opening to slow equalization. As the difference in pressure  between the sinuses and the flight deck increases, congestion  may plug the opening. This “sinus block” occurs most  frequently during descent. Slow descent rates can reduce the  associated pain. A sinus block can occur in the frontal sinuses,  located above each eyebrow, or in the maxillary sinuses,  located in each upper cheek. It usually produces excruciating  pain over the sinus area. A maxillary sinus block can also  make the upper teeth ache. Bloody mucus may discharge  from the nasal passages.  This procedure forces air through the Eustachian tube into the  middle ear. It may not be possible to equalize the pressure in  the ears if a pilot has a cold, an ear infection, or sore throat.  A flight in this condition can be extremely painful, as well as  damaging to the eardrums. If experiencing minor congestion,  nose drops or nasal sprays may reduce the risk of a painful  ear blockage. Before using any medication, check with an  AME to ensure that it will not affect the ability to fly.  sensitivity, pinch the nostrils shut, close the mouth and lips,  and blow slowly and gently into the mouth and nose.  17-5  Middle Ear and Sinus Problems  Figure 17-2.  The Eustachian tube allows air pressure to equalize  in the middle ear.  •  Visual impairment  •  Unconsciousness  •  Lightheaded or dizzy sensation  •  Tingling sensations  •  Hot and cold sensations  •  Muscle spasms  Opening to throat  Middle ear  Outer ear  Auditory canal  Eustachian tube  Eardrum 