Electric Ray Attack & Oxygen Toxicity Inquiry

[Air_Diver_M.E.]

Good day.

I am working as an air (HSE-part-1) commercial diver and recently, I had a near miss while working underwater and would like to be advised and to inquire regarding the incident.

Forty five meters (45m) below after working for 20 minutes, suddenly I felt an electric shock in my body, felt it for three times. First and the second time I felt the shock, right away I called for help from the radio connected above. The third time, I lost consciousness and was pulled back and brought inside the recompression chamber. I got conscious again after half an hour inside the chamber itself. Underwater, when I was still conscious and asking for aid, my thought was: there must be an earth leakage on some of the electrical motors on the flat form. But then again, after the investigation it was confirmed that there was no leakage at all. The supervisor, client and other divers present in that time believed that the cause of the electric shock I got was only from an attack of an electric ray (i.e. torpedo ray) thru a volt discharge.

BUT – I am not convinced with the explanation given to me because when I was still conscious underwater, I am 3m off from seabed and did not see any fish around or near me. I believed that an electric ray (of any species) is always buried under the mud/sand and they rarely swam near the seabed only. I have been into this field for 15 years now and have encountered electric rays a couple of times while diving this depth or more – but have not gone unconscious because of being contacted with it, and as per my knowledge these species never attack and could not attack thrice continuously as they need to energized or recharge their selves even before they can produce another volt and I felt the electricity passing from my head inside my body and not coming from outside.

Therefore, I doubt that there must be a mistake thru negligence that the person in-charged that time opened the NitrOx valve 50/50 at the same time with the main air, on that depth of 45m instead of changing the breathing medium at 90 ft. for deco to NitrOx 50/50 alone to the surface.

NOW – kindly advice me for clarification of any fact and figures that divers (around the world, if any) got attacked by electric ray of any different species and had the same incident as mine. I got unconscious underwater due to that electric shock feeling I received for three times (continuously). I just got out from the hospital yesterday afternoon since the accident and had been in the ICU for 5 days. Complications in my heart (i.e. irregular / abnormal heartbeat / chest pain / problems in breathing) occurred after that incident. As of now I am under recuperation for a for another week and have been searching for some facts. I would like to know the exact reason / explanation enable to convince me, also to share my experience to other commercial divers in my field.

Please send me any information regarding O2 toxicity on this depth I had been during the incident (i.e. 45m), including the symptoms and warnings of the same. I would very much appreciate if anybody in this site could kindly provide some knowledge regardig the same.

Thank you very much, in advance.



Best regards

Felix

 

[wedivebc]

If you are having long term effects from this incident then it was not likely caused by an O2 tox event. I would suspect you got shocked by a man made source but for sure I would consult a Dr who specializes in dive medicine. DAN maybe?

 

[DocVikingo]

Hi Felix,

There are a large number of identified species of electric/torpedo rays (order Torpediniformes). Although you provide no description of where you were diving, I suspect it was in the Middle East.

If so, electric rays reportedly are common off the East Coast of the UAE and Oman (e.g., Torpedo adenensis) and Western Indian Ocean (e.g., Torpedo alexandrinsis), although to the best of my admittedly limited knowledge these tend to be small in size and to generate voltages that are relatively benign to humans, say in the 35-50 volt range. The largest species, the Atlantic torpedo, Torpedo nobiliana can reach 90 kilograms and deliver 220-volts.

While you are correct that torpedo rays tend to spend most of their time along the bottom/partially buried in the sand, some reportedly can be rather confrontational and if irked will go after divers [e.g., Pacific torpedo ray (Torpedo californica)]. I have no idea if this is true of species in the Middle East region.

While I suspect you are correct that electric rays endeavor to conserve their charges, much like poisonous sea snakes tend to conserve their venom, using just enough to deter predators/immobilize prey, the literature reports torpedo rays indeed are capable of repeated discharges if sufficiently provoked. I have no idea if this is true of species in the Middle East region.

Concerning the issue of could an electric ray produce the signs and symptoms which you describe, a major hit from an Atlantic torpedo probably could cause transient problems with breathing. However, the development of continued breathing difficulty, and even more so the development of a continuing cardiac arrhythmia (were you diagnosed with ventricular fibrillation?), strikes me as extraordinarily unlikely.

As regards oxygen toxicity, you'll want to read up on the Paul Bert effect. With ox-tox the diver can show muscle twitching & spasm, nausea & vomiting, tunnel vision, tinnitus, twitching of facial muscles, irritability, confusion, anxiety, trouble breathing, extreme fatigue, incoordination and even convulsion. However, given the depth, time and gas mixtures you mention, not mention the continuing effects you are experiencing, the ox-tox hypothesis strikes me as even more unlikely than that of being hit by an electric ray.

Like you, I am not convinced that the etiology of your complaints has as yet been adequately explained. Please keep us posted as matters develop.

Best of luck,

DocVikingo

 

[drbill]

I posted a reply in your other thread but will add to it here.

As I said, I am not familiar with the electric rays of the Middle East. The Pacific torpedo or electric ray can, as DocVikingo stated, deliver multiple jolts of electricity and have been known to turn and threaten or go after divers (like me) if they pursue them too close.

I just spoke yesterday with a diver who had one envelope him from above and deliver a few good jolts. If one was above you, rather than in the sand, I think you would have received a bigger jolt since the electric charge is largely delivered downward (they stun or kill prey by hovering above it or wrapping it in their wings and delivering the charge).

 

[Dr Deco]

Hello Felix :

I have no experience with electric fish and cannot comment on them.

Oxygen toxicity produces all the effects mentioned by DocVikingo but, as he said, not the heart problems and lasting effects that you describe.

Dr Deco :doctor:

The next class in Decompression Physiology for 2006 is September 16 – 17. :1book: http://wrigley.usc.edu/hyperbaric/advdeco.htm[/url