BAROTRAUMA
There are a number of air spaces within our bodies. Examples of these space are our sinuses, ears and lungs. If the air in these spaces are not equalised with the ambient pressure, they can be damaged. This is known as barotrauma.
LUNG BAROTRAUMA
The failure to allow air in the lungs to expand while the diver ascends is the main cause of lung barotraumas. The trap air expands as the ambient pressure decreases according to Boyle's Law as the diver goes to shallower depths. If the air is not allowed to escape, the alveolar membrane will stretch and excessive stretching would allow minute air bubble to enter the capillaries and then the blood stream. This condition is called Air Embolism. These tiny bubbles would block fine capillaries especially those in the brain. The brain would then be starve of oxygen and neurological disorders follow (Type 2 DCS). Symptoms include giddiness, difficulty in breathing; leading on to numbness, paralysis, heart failure and death eventually.
If the lung tissue continues to stretch, it will eventually tear. Larger bubbles form and get trapped between the lung sacs and chest walls. This condition is called Pneumothorax and can cause the lungs to collapse due to the pressure of the trapped air becoming greater than that in the lungs. Symptoms are cyanosis, shortness of breath, coughing of blood, painful breathing. The chest cage would also appear swollen.
Interstitial Emphysema, where air gets trapped around the vicinity of the heart and major blood vessels, complicating blood circulation. Symptoms are shortness of breath, coughing of blood, painful breathing, difficulties in swallowing and swelling of the skin at the neck base.
Treatment for lung barotrauma is immediate decompression treatment. Surgery is also required for burst lungs and can be done within recompression chamber if required. Administration of pure oxygen may help ease symptoms of Type 2 DCS.
EAR BAROTRAUMA
Effects of pressure change can be felt within 2 meters from descending the surface. External water pressure exerts force on the ear drums inwards. The pain felt is due to the ear drums bending towards the middle ear to in a bid reduce the volume to compensate an increase in external pressure. If the pressure difference is not equalized, the ear drum could rupture. When this happens, water rushes in to the middle ear. The diver can feel this rush of water in his ears and sudden relief of pain, however the rupturing of the ear drum can lead complications such as deafness, vertigo and infections. Bleeding at the ears is also a sign of barotrauma.
Equalization is done either by swallowing or using the 'Valsalva maneuver' where the diver holds his nose and blows. Both methods open the Eustachian tube and allow air to enter the middle ear to balance the pressure difference. Diving with nasal infection or congestions is therefore not recomended because, the eustachian tube would be blocked with mucus, causing the diver to have difficulties in equalizing. Forcing equalization during a flu is dangerous because this can cause the infection to go into the middle and inner ear resulting in more complications. Normally during ascend, the extra air in the middle ear from expansion escapes down the eustachian tube, but during a flu, air cannot escape down and the extra pressure pushes the ear drum outwards. This condition is called Reversed Block.
Another way a reverse block can occur is when something eg. water is obstructing the outer ear. Increasing pressure from the middle ear cavity pushes the ear drum outwards. Rupturing can happen if left unchecked. Descending again to a lower and slowly ascending can help clear the reverse block.
SINUS BAROTRAUMA
Sinus are air spaces within the head. Barotraumas are cause by blockages in the air passages in the paranasal sinuses. Normally sinuses clear automatically or as a result of clearing the ears. In instances of nasal congestion, when mucus can block these passages, the imbalance of pressure causes pain. This is called a sinus squeeze. If not relieved, the build up of pressure can cause the linings of the sinus membrane to burst and bleed. Blood then fills up the sinus cavity and relieves the pain. Tell tale signs of sinus barotrauma is a blood and mucus mix filled masks when the diver surfaces. Not a very pretty sight plus infections of the sinuses might set in.
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