Unknown Tourist dead, Dive Master ill - Ambergris Caye, Belize

[CT-Rich]

The safety stop is a pretty low priority in an emergency. In the absence of other information, I would skip it. If the distressed diver is going to pass out, it is better to do it on the surface. If they are breathing contaminated air, they are better off on the surface, dumping weights, blow up the BCD and breathing surface air. If you are far away from the boat, you can signal for an emergency pickup three minutes sooner.

Reading the initial article, I wasn't 100% clear on whether there four divers in the water or three. With the DM unconscious, his rescuer had no choice but to stay with him until pickup. It also wasn't clear if the diver that died was indicating he was in distress. That he went straight to the surface before passing out would be a good indicator that he was. 20-20 hindsight, being only three divers in the group, they should have stayed together (i.e. the rescuer should have followed the other diver with the DM in tow) all the way to the surface, dumped weights and made everyone buoyant and face up out of the water while waiting for a pick up. That was a very tall order and not knowing what was up with the diver that died, impossible criticize.

Unless a deco obligation is involved, it is easier to fix bent rather than drowned.

 

[dmaziuk]

Possibly Mr. Hughes had a different emergency that had him ascend too quickly and then having become injured, he was unable to inflate his bcd to keep him at the surface.

It's possible but that's looking for zebras. Considering the overall frequency of diving incidents, for two of them to happen on the same dive, it is more likely there was a common cause.

 

[tursiops]

But I agree that the agencies have really defaulted to always do a SS

Not clear to me that this is the case.
PADI RDP does NOT default to a SS.
PADI computer training says default to what the computer says, which may or may not suggest a safety stop, so that is not really on the agency.
Various dive ops (or even countries, like the Cayman Islands) may default to always doing a SS, but that is not on the agency either.

 

[MidOH]

Yeah. If my computer reads no stops, I'm going to the surface. It's already in a conservative tech mode.

My buddy is turning blue. To heck with the safety stop.

 

[rmorgan]

Possibly Mr. Hughes had a different emergency that had him ascend too quickly and then having become injured, he was unable to inflate his bcd to keep him at the surface.

It's possible but that's looking for zebras. Considering the overall frequency of diving incidents, for two of them to happen on the same dive, it is more likely there was a common cause.

Hmmm--I'm not sure about that (the zebras) at all. While little is known about Mr. Hughes's situation, there are significant differences. He was ascending with the other three, "following us slowly on the way up. Behind me but, his US DM buddy could see portions of him behind me, and verified he was tracking slowly with [their] ascent," and never signaled distress to his buddy otherwise or approached us to offer assistance with the Belizean DM." But when he brought back up from his apparently-uncontrolled sinking, he was bleeding from the mouth--a symptom of pulmonary edema--and drowned.

Given the knowns, It's not even clear what the "zebras" would be: Bad gas on two of three divers with nitrox, all three from the same source, or two divers having different but serious physical problems a few minutes apart?

In either event, though, the whole safety-stop focus, while an informative discussion of standards and best (or not-best) practices, does not seem especially relevant to what actually happened, since Mr. Hughes apparently skipped his safety stop but then drowned, and the unconscious DM was quickly revived once onboard the vessel, partial safety-stop or not. I am not a safety-stop devotee, but the whole issue seems like a rabbit (zebra?) trail here.

 

[dberry]

I don't think that any of those would measure in the 10ppm range.

I use gallon ziplocks with handles for rapid closure to try to avoid ambient fumes with my Sensorcon CO, waiting a full minute.

This cost $139 a few years ago. Ziplock bag method works fine, imo. Waiving this around in the garage after the car running for only 1 minute registered 5ppm. EPA says the limit is 50ppm ( 8 hours exposure). At depth the partial pressure of CO will be higher than on the surface, of course (e.g. 4x at 99 ft). BUT your tank fills should read Zero ppm CO. Seeing any reading >0 would make me reject the tank.

 

[DandyDon]

BUT your tank fills should read Zero ppm CO. Seeing any reading >0 would make me reject the tank.

Oh, the Sensorcon CO FAQs mention that "At concentrations lower than 20ppm, the accuracy is +/-2ppm," so I'd allow a little leeway. Too, there's a chance of capturing ambient fumes in the bag. Even 10 ppm isn't going to hurt me taken to 100 feet so I'd dive a tank up to that.

 

[dberry]

Oh, the Sensorcon CO FAQs mention that "At concentrations lower than 20ppm, the accuracy is +/-2ppm," so I'd allow a little leeway. Too, there's a chance of capturing ambient fumes in the bag. Even 10 ppm isn't going to hurt me taken to 100 feet so I'd dive a tank up to that.

I suppose, but I'd feel better using a 5ppm cut-off on the surface. Just because 50ppm is the "safe limit", I wonder how much would it take to alter coordination or judgment?

 

[DandyDon]

I suppose, but I'd feel better using a 5ppm cut-off on the surface. Just because 50ppm is the "safe limit", I wonder how much would it take to alter coordination or judgment?

Okay, a 5ppm cutoff is more reasonable than zero. The +2ppm sensor variance makes zero an unreasonable goat. Of course, the unit might read 10ppm for 12ppm, so one wouldn't want to be too liberal. I rejected a tank a couple of years ago for 10 and they had to send another tank out from town, but I should have tested twice as I might have allowed some motor fumes in the bag. Skill counts.

We certainly don't want to be diving any 200ppm tanks, and those do happen. They just don't get caught often.

 

[Outbound]

Hmmm--I'm not sure about that (the zebras) at all. While little is known about Mr. Hughes's situation, there are significant differences. He was ascending with the other three, "following us slowly on the way up. Behind me but, his US DM buddy could see portions of him behind me, and verified he was tracking slowly with [their] ascent," and never signaled distress to his buddy otherwise or approached us to offer assistance with the Belizean DM." But when he brought back up from his apparently-uncontrolled sinking, he was bleeding from the mouth--a symptom of pulmonary edema--and drowned.

My first thought was that Mr. Hughes may have breathed contaminated air but managed to surface, slip into unconsciousness, and sink to the bottom. The bleeding from his mouth may have been caused by a post-mortem AGE that was the result of bringing him to the surface. If he wasn't breathing and had a closed airway, any air remaining in his lungs could have caused an embolism.

I fully admit this is 100% conjecture, however.