Almost unconscious during Dive

[DON-PNW]

Also, here is a description of Alternobaric Vertigo: Alternobaric vertigo (AV) is a highly descriptive term coined by Dr. Claes Lundgren in 1965.3 Alter means other, bar means pressure, ic means the condition of, and vertigo is the perception that the body or its surroundings are spinning or moving. AV arises from unequal pressure between the two middle ears, usually because the pressures are changing at different rates. Failure to equalize pressure symmetrically can cause the brain to erroneously perceive the difference as movement. Nystagmus (involuntary rhythmic movement of the eyes) can also occur, as can nausea and vomiting in severe cases. In addition to visual disturbances, AV events may be accompanied by the feeling of fullness, tinnitus (ringing in the ears) and muffled hearing in one or both ears. Some divers may notice a hissing or squeaking sound, indicating poor equalization, prior to the onset of AV. Women appear to have a greater susceptibility to the condition than men.1

 

[Kevrumbo]

Thank you everyone for your comments. I did check my air in the tank and it came back just fine. I did end up going in for a consult (this happened again a couple days after this event) with a specialist and after going through it in detail and answering the doctor's questions he is confident that the problem I was experiencing is what is called Alternobaric Vertigo. This is just a good reminder that diving while congested can lead to problems especially if you are not patient (as in my case) with properly clearing upon decent.

Also, here is a description of Alternobaric Vertigo: Alternobaric vertigo (AV) is a highly descriptive term coined by Dr. Claes Lundgren in 1965.3 Alter means other, bar means pressure, ic means the condition of, and vertigo is the perception that the body or its surroundings are spinning or moving. AV arises from unequal pressure between the two middle ears, usually because the pressures are changing at different rates. Failure to equalize pressure symmetrically can cause the brain to erroneously perceive the difference as movement. Nystagmus (involuntary rhythmic movement of the eyes) can also occur, as can nausea and vomiting in severe cases. In addition to visual disturbances, AV events may be accompanied by the feeling of fullness, tinnitus (ringing in the ears) and muffled hearing in one or both ears. Some divers may notice a hissing or squeaking sound, indicating poor equalization, prior to the onset of AV. Women appear to have a greater susceptibility to the condition than men.1

I have at times chronic alternobaric vertigo, and it always occurs during ascent when one ear releases to lower ambient pressure before the other, with the resultant immediate and very bad sensation of the entire underwater scene spinning wildly out-of-control into potential loss of consciousness. I usually re-descend slightly deeper and/or then re-clear my ears with a valsalva and the spinning will usually stop. Last resort is to continue the ascent holding onto a Buddy or an anchorline/upline until the other ear clears & equalizes.

This same type of vertigo can be produced by unequal caloric stimulation of the eardrum, as with colder water entering the undermost ear in the prone position. An external ear canal partially blocked with wax (which I also have problems with excess cerumen production & impaction) can cause this inequality as well.

With your reported initial symptoms @DON-PNW beginning on descent, with no mention of acute middle ear pain, frank dizziness or vertigo symptoms, or even mention of equalization problems (but just nausea, skin & head tingling sensation, feeling unwell, hard to concentrate, and finally about to pass out at reaching depth 70fsw), I'm not sure that this is all attributable to either Ear Barotrauma on descent, or Alternobaric Vertigo on ascent.

Again, Rule Out metabolic CO2 retention, vs Ear Barotrauma, vs Alternobaric Vertigo as differential diagnoses. The remedies to cover all these cases are to equalize early and often, breath full inspiration/expiration ventilatory cycles, don't exert yourself into heavy physical exercise, and don't dive at all with an upper respiratory, middle ear and/or sinus congestion/infection.

 

[Duke Dive Medicine]

DON-PNW,

I'll trust the individual who evaluated you in person, but as Kevrumbo stated, your initial description of your event does not match alternobaric vertigo. I'd echo what he said in that you should be on the lookout for other potential causes.

Best regards,
DDM