A free diver (non-SCUBA) can dive to 33 feet or 10 meters and safely ascend without exhaling because the gas in the lungs had been inhaled at the surface at atmospheric pressure. Breathing gas at depth during SCUBA causes the in gas in the lungs to be at a higher pressure than the atmospheric pressure. Pulmonary barotrauma on the ascent is the most serious and potentially life-threatening.
Ear, sinus, and dental injury may occur on the ascent as well as descent. Barotrauma of ascent is caused by the volume increase of gas containing spaces. Sinus squeeze usually occurs in divers with some degree of chronic sinusitis, allergies, URI, mucoperiosteal thickening, nasal polyps, and ostial occlusion. Sinuses are truly closed spaces, except for the functioning of their ostia. And carious teeth may implode on the descent. Dental pain is caused by similar pressure effects at the site of fillings, apical abscesses, or carious teeth. Tinnitus, sensorineural hearing loss and vertigo are common.
Barotrauma youtube windows#
The round and oval windows of the inner ear may rupture, with a concomitant perilymphatic leak. This is usually in the setting of severe (locked) Eustachian tube, allowing a large pressure gradient. Occasionally inner ear barotrauma may occur. Drownings have occurred due to disorientation or vomiting. This may present with disorientation, nausea, vomiting, vertigo, and tinnitus. When this gradient differential exceeds 45mgHg, alternobaric vertigo may occur. Occasionally the pressure gradients across the left and right TMs differ asymmetrically, usually due to eustachian tube mismatch. However, hearing loss, whirling vertigo, tinnitus, and bloody drainage may ensue. Curiously this is heralded by a sudden decrease in pain. At 100mmHg gradient, the Eustachian tube cannot open, and TM hemorrhage and rupture may occur. However, if the pressure gradient exceeds 30mm, pain will ensue. On the descent, as pressure builds up between the ear canal, TM, and the nasopharynx, the Eustachian tube should function to equalize this. The actual rupture of the tympanic membrane (TM) is a consequence of ear ‘squeeze’ and usually occurs in divers with Eustachian tube dysfunction. The resulting pressure difference between the tissues and the gas space causes injury. Any patient receiving mechanical ventilation is at risk for barotrauma, but it is most commonly seen in patients with acute respiratory distress syndrome (ARDS).īarotrauma of descent is caused by a lack of pressure equalization in closed spaces in contact with the diver, typically the ear, teeth, sinuses, and face mask. Risk factors for barotrauma include asthma, sinusitis, dental abscesses and caries, chronic obstructive pulmonary disease (COPD), seizures, ear problems, syncope, panic disorders, vertigo, poor training, inexperience, and Eustachian tube dysfunction. Peripheral embolism of the gas bubbles occludes the circulation, with potential for cerebrovascular accident or cardiac ischemia. The most serious consequence of barotrauma is a pulmonary alveolar rupture with antecedent air gas embolism. Additionally, injury to the lung from positive airway ventilation is a special case of barotrauma. The most serious form of ascent barotrauma is pulmonary injury. Barotrauma on ascent may similarly result in the ear, sinus, and dental trauma (tooth explosion).
Sinus squeeze can be excruciating, usually in the setting of chronic sinusitis with occluded ostia. Ear squeeze can occur in the ear canal or middle ear.
Barotrauma youtube skin#
Mask squeeze can cause skin ecchymosis imprinting the mask pattern on the face, conjunctival hemorrhage, and rarely, orbital hemorrhage. Dental squeeze can cause an implosion of carious teeth. The ‘squeezes’ are caused by the inability to equalize pressure on the descent, classically across the face mask, sinuses, teeth, or ear. Barotrauma occurs most commonly while scuba diving, but also may occur during flying, mountain climbing, or skiing. During scuba diving, barotrauma may be caused by descending or ascending too rapidly. Due to the density of water, pressure during a dive increases one additional 1 Atm for every 33 feet of seawater depth. Both of these measurements are equivalent to one atmosphere (1 Atm or 1 Barr). This is also measured in millimeters of mercury as 760mmHg. Atmospheric pressure at mean sea level is 14.7 psi.
Similarly, the compressed air held in a diver’s lung, if he holds his breath, will expand as the surrounding water pressure decreases on the ascent. A balloon that rises in the atmosphere will expand in volume as the ambient pressure decreases. According to Boyle’s Law of Gases, if the temperature of a gas is held constant, there is an inverse relationship between the volume of the gas and its pressure.
0 kommentar(er)
