![]() These barotraumas usually manifest as postnasal drip or bloody discharge from the nose, depending on the sinuses involved. While ascending, any remaining gas within the sinus expands and forces out this blood and mucus. At this point the pain usually resolves or diminishes, and the diver continues the dive. The capillary vessels of the mucous membranes lining the sinuses engorge and burst, likely filling the sinuses with blood until the negative pressure is equalised. The first sign of this type of sinus barotrauma is generally a sharp pain. The mechanisms of injury of sinus barotraumas depend on whether it happened during descent or ascent.įailure to equalise pressures on paranasal sinuses while descending keeps these cavities at atmospheric pressure, which results in a relative negative pressure (vacuum) as you descend to depth. While ascending, the increasing volume usually vents itself passively. While descending, it is imperative that divers actively or passively equalise all enclosed air-filled spaces to avoid injury. As the ambient pressure decreases while ascending, the volume of the gas increases proportionately. According to Boyle’s Law, as the ambient pressure increases while descending, the volume of the gas in an enclosed space decreases proportionately. The pressure diminishes by the same amount on ascent. Ostia blockage can impair drainage and make both descents and ascents troublesome.Įvery foot of descent in water adds approximately one-half pound of pressure on each square inch of tissue. The ostia can easily be blocked by inflammatory processes, like colds or allergies, and in divers by improper attempts at equalization. ![]() The paranasal sinuses communicate with the nasal cavity via small orifices called ostia (singular: ostium). The maxillary sinuses (area four) are located within the maxillary bone below your eyes and lateral to your nose and are the largest pair of paranasal sinuses.The sphenoidal sinuses (area three) are centrally located behind the nasal cavity and vary in size and shape.The ethmoid cells (area two) are located within the ethmoid bone between your eyes and nose and are formed by a variable number of connected individual cells.The frontal sinuses (area one) are located within the forehead above your nose and eyes and are surrounded by thick, bony walls.There are two sets of four sinus cavities, one set on the right and one on the left. They have several functions: They lighten the weight of your head, play a significant role in the resonance of your voice, serve as collapsible structures that protect vital organs during facial trauma, and may help the turbinates (small structures inside the nose) humidify and heat the air we breathe. The paranasal sinuses are gas-filled cavities in your facial bones and skull. ![]() Divers should never underestimate difficulties equalising sinuses.Īnatomy and Functions of the Paranasal Sinuses Although sinus barotrauma is a prevalent and generally benign diving injury, some of its complications could pose a significant risk to the diver’s health. When the paranasal sinuses fail to equalise to barometric changes during vertical travel, damage to the sinus can cause sharp facial pain with postnasal drip or a nosebleed after surfacing. Sinus barotraumas are among the most common diving injuries.
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