Dr Deb Mitchell TMA member in Alice Springs
I am wearing close to 40kg of extra weight with all the gear for my first dive (needless to say I am not keen to reveal my baseline weight but let’s just say it’s a lot!!) and as a group we are walking from the car park at Alma Bay on Magnetic Island off the coast of Townsville, wearing full-length wetsuits, and I pretend not to notice the stares of strangers.
I am excited, yet nervous as all hell, hot with the sun baking on the wetsuit material, and can feel my face getting redder, as I try not to huff and puff like a steam train. I am slightly reassured as my younger colleagues complain about how heavy the tank and weight belts are.
There is no avoiding it now; my first ever dive is about to happen, and the instructor has already stated that “if we can dive in these conditions, we can dive anywhere”. I appreciate he is trying to build us up, but my anxiety peaks as we walk out from the shore into the ocean, and fully inflate our BCs and struggle to attach our fins as the waves crash over us. I am doing this “Open Water Diver” course a few days before my Masters subject of “Diving and Marine Medicine” and can’t stop my mind thinking of all the potential common complications for novice divers.
Barotrauma encompasses tissue damage caused as a direct result of the changes in gas volumes that occur with changing ambient pressure (this is known as Boyle’s Law). Pressure is inverse to volume, and air in sinus cavities, middle ear and lung will expand as the pressure decreases and vice versa. The commonest injury to novice divers is middle ear trauma as people cannot equalise their ears (Valsalva manoeuvre) as they go underwater and go to depth. If the eustachian tube is blocked due to a head cold or upper respiratory infection, you will find it hard to equalise and the eardrum will bulge inwards and things start to swell, which is why you start to experience pain. It is a good idea to ensure you have practiced the Valsalva manoeuvre prior to any diving and if you have any signs of a head cold it is a good idea to delay any planned activities.
As I reflect that my instructor did not make me do a diving medical (just the questionnaire) I was pleased I had chosen to get my own baseline audiometry test prior to this course as despite no URTI symptoms, by the end of the 4thdive, I certainly had some ear discomfort. If someone did burst an eardrum while diving, it is recommended that you cannot fly or dive until the condition has resolved, which depending on the size of the hole could really take weeks to months, which may dramatically impact on that overseas island-hopping holiday.
Pulmonary (lung) barotrauma of ascent occurs when expanding gases within the lung cannot escape. The lung tissue may then over distend and tear and this damage to the lung can allow gas to move into the vascular compartment of other potential cavities in the body. There are three main problems from this which are very serious; Arterial Gas Embolism, Pneumothorax and Emphysema. Predisposing factors for pulmonary barotrauma of ascent include anything that restricts gas flow from the lungs. These can include being a smoker (perhaps undiagnosed COPD- emphysema), asthmatics, even if well controlled, heart conditions and simply diving with colds and viral URTIs which cause congestion.
See Picture: Lung compression
The rule of diving is to always breathe, and in particular when ascending to always breath out. Looking at the picture of the lungs you can see the volume of the lungs will expand by 50% from 10 metres of depth to the surface and is you panic, and hold your breath as you quickly ascend (which a novice diver is more likely to do) you can seriously injure yourself. It is a skill to slowly and rhythmically breathe in a deep inhalation, followed by a deep exhalation, watching my bubbles escape to the surface. You use more air the deeper you dive. Lungs can only withstand an overpressure of 0.12 bar which is only 1.2m depth so even when snorkeling to dive down to have a closer look at the reef/ coral, if you do not breath out as you ascend you can damage your lungs.
NEVER HOLD YOUR BREATH WHILE ASCENDING.
See pictures of the hyperbaric chambers below.
As I reflect on achieving a brand new skill at the age of 48 years, and start to plan my next dive, I am very conscious of the need to dive again soon to ensure my fear does not over-ride my want for new adventures. I am extremely lucky to have an instructor to diver ratio of 1:2 on Magnetic island, and when looking at an upcoming trip to Thailand where diving on Ko Tao looks amazing, the ratio is closer to 1:30!! I am pleased I learned in Australia but I look forward to seeing more underwater than just a few tiny fish hidden in the rocks due to the crazy conditions I learnt in back in October. If you are considering diving on your overseas holiday, or even snorkeling, feel free to have a look on our website for more information about Diving Medicine, and consider doing a formal Diving Medical (even if not asked to by your Diving school) to ensure you are safe to dive, and have a baseline hearing and lung function test. SPUMS is an organisation that lists doctors accredited to do Diving Medicals in the South Pacific.
