Hi all,
This scenario has probably come up a few times before but I'd like to share my experience in the hope that it might be of interest to others. I am a technical instructor, doing technical dives on a frequent basis (generally always on courses up to advanced trimix). Apologies in advance for the long account, but I appreciate any that stay the course and read to the end
Last year in October I conducted a dive, 40m on air (twinset 11L) with a 5 minute deco obligation. I had a 36% stage that I used for deco from 21m. The profile included a bounce at the deeper portion 40 -> 30 -> 40 -> 30, never something that would normally occur on a typical dive but was required unexpectedly on this one. I had also done some routine exercise in the morning, 4 hours prior to the dive, light cardio and some bodyweight exercise that I was well conditioned for.
After the dive (simple in comparable terms) I had some pain and numbness in my upper left arm and shoulder. This occurred approximately 15-20 mins after the dive. This worsened in intensity over the following two hours and while it was not extreme, I put myself on O2 and went to see the local hyperbaric doctor which thankfully is only 15 minutes from our dive centre. The O2 made little difference but given the proximity of the chamber, I was not on it for very long. A slight tingling developed in my left hand.
After conducting a neuro (no problems) and physical assessment, he pronounced a minor type I DCS and recommended a US navy table 6 chamber treatment, which I accepted with some hesitation, an amount of denial present that I could actually be bent after such a dive when I had conducted so many dives prior much deeper with far greater deco obligations. The hyperbaric doctor and I concluded that the reason must have been the existence of both the saw-tooth bottom section of the dive and pre-dive exercise. There were two others on the dive with me, with the same profile, who had no issue.
After minutes on O2 at 2.8 bar in the chamber, all bad sensation in my arm had gone leaving me to conclude that it must have been DCS and I had a further 5 hours to think about just what implications this now had upon my diving and my career. I know plenty of people in all parts of the industry across the world that have been bent to some degree (thankfully no serious cases) at various times in the past. Still, I did struggle to accept that it had actually happened to me given the meticulous way with which I typically conduct all dives I perform.
Due to the speed with which the symptoms disappeared in the chamber and their severity prior to it, the hyperbaric doctor prescribed no diving for 4 weeks with a followup then to ascertain whether diving could commence. With my frustration, I followed this advice exactly and 4 weeks later was absolutely fine and signed off for diving. Shallow, no-deco dives to begin with of course but happily upon beginning technical dives once more after a safe period, I had no repeat hits. A big relief for sure.
Approximately a month ago, I was again on a 40m dive with minimal deco obligation (final dive of Tec40 course), in twinset air + 50% and the exact same sensation returned again. I was horrified. The dive profile was perfect, very conservative, great conditions, I was well hydrated and I had done no exercise. Since the first incident however, I had read plenty of material and before sending myself off to the chamber this time I decided to take some muscle relaxants and head home to rest and continue hydrating. There was certainly an improvement, pain disappeared, still a bit numb but nothing that concerned me. I went to sleep.
In the morning I woke feeling fine but within minutes of getting out of bed, the pain and numbness intensified again. Feeling experimental, with nothing to do, I went to the dive shop, put myself on O2 and waited for 45 minutes. There was a drastic improvement again, I took anti-inflammatories and went home to rest for the day. The next day I was also dry and felt fine. Must be a muscular issue. The following day I was in the water at 5m teaching a sidemount course and after the dive, back came the same sensation.
Logic tells you that there is no way you can get hit at 5m...unless of course you have just been hit a few days prior and the tissue is severely damaged. The mind plays many tricks upon you in such a situation and I decided to be sensible and phone DAN. The DAN doctor, rather hurriedly informed me that if medication made the pain subside it wasn't DCS. I went to sleep. The next day it was worse, very numb, tingles in my hand, slight throbbing sensation. So back to the local doctor I returned, another neuro and physical and he confirmed no DCS, just a muscular issue, rest and continue anti-inflammatories, muscle relaxants and allow recovery.
I stayed dry for two weeks, in some sense actually fearing returning to the water in case of another episode. Finally I forced myself to ignore my internal mind games, enter the water and confront it. All was absolutely fine. Back to my normal diving schedule. Fast forward to two days ago and I am doing a 55m training dive, twinset, trimix, two decos, 80 minute dive time with a lot of swimming. Once again the same situation happens, 10-15 minutes after the dive, intensifying over time. This time I wasted no time in taking some fairly strong muscle relaxants and anti-inflammatories with a large amount of water while doing a classroom theory session. By the evening my arm was 100% ok. The following day we did 65m to finish a Tec65 course which went perfectly, and all was ok after the dive.
Finally I arrive at my learnings from the last few months. While I will never know for certain, I strongly believe that I was never bent in the first place. I think that something about being in a twinset combined with my trim posture during deco pinches a nerve and creates symptoms that can be confused with a type I hit. Breathing 100% O2 probably does help the issue as I am in a relaxed posture while on it. I have spoken to some during this time that have, based on their own experience, said that a DCS hit really, REALLY hurts and that the description of my symptoms does not sound extreme enough.
Still, it is a tough sitution to be in. I consider myself to have a very high knowledge of dive physiology and decompression theory and practice, though when faced with potential symptoms, erring on the side of caution that first time was certainly a sensible idea. From the doctor's perspective as well, given that I was full DAN insured, he was maybe erring on the side of caution by putting me in the chamber also. In summary, there are a few things that I take from my experiences:
- A trapped nerve can produce symptoms very similar to that of type I DCS
- Whether at fault or not, a saw-toothed profile between 40m and 30m is still to be avoided
- Keep the bodyweight exercises away from deep dives regardless
- If the sensation of a possible hit is minor, perhaps muscle relaxants / anti-inflammatories should be tried first and a self-assessment made (MY OWN GUIDANCE, NOT ADVICE I AM PRESCRIBING TO ALL, I AM NOT A QUALIFIED DOCTOR)
- If medications cause symptoms to subside, it probably isn't DCS (as confirmed by DAN doctor over the phone, but still DO NOT TAKE AS GUARANTEED, SEEK YOUR OWN MEDICAL ADVICE).
I hope my account provides some amount learning. Ultimately of course, I would advise any diver to have a comprehensive insurance cover so that if you ever question yourself or someone else having DCS, you immediately take appropriate action (lay down, breath 100% O2) and get yourself to emergency medical/hyperbaric care. Being in the chamber is not a fantastic experience, and there are certainly considerations that should be made about going there, but let the hyperbaric professionals make that assessment and feel safe in the knowledge that if it does have to happen, your insurance is there to cover the financial aspect. I know that in my case, my DAN coverage was invaluable. I had a single accident report to fill in, and then the rest was handled entirely between DAN and the hyperbaric chamber.
Thank you for listening ;-)
This scenario has probably come up a few times before but I'd like to share my experience in the hope that it might be of interest to others. I am a technical instructor, doing technical dives on a frequent basis (generally always on courses up to advanced trimix). Apologies in advance for the long account, but I appreciate any that stay the course and read to the end
Last year in October I conducted a dive, 40m on air (twinset 11L) with a 5 minute deco obligation. I had a 36% stage that I used for deco from 21m. The profile included a bounce at the deeper portion 40 -> 30 -> 40 -> 30, never something that would normally occur on a typical dive but was required unexpectedly on this one. I had also done some routine exercise in the morning, 4 hours prior to the dive, light cardio and some bodyweight exercise that I was well conditioned for.
After the dive (simple in comparable terms) I had some pain and numbness in my upper left arm and shoulder. This occurred approximately 15-20 mins after the dive. This worsened in intensity over the following two hours and while it was not extreme, I put myself on O2 and went to see the local hyperbaric doctor which thankfully is only 15 minutes from our dive centre. The O2 made little difference but given the proximity of the chamber, I was not on it for very long. A slight tingling developed in my left hand.
After conducting a neuro (no problems) and physical assessment, he pronounced a minor type I DCS and recommended a US navy table 6 chamber treatment, which I accepted with some hesitation, an amount of denial present that I could actually be bent after such a dive when I had conducted so many dives prior much deeper with far greater deco obligations. The hyperbaric doctor and I concluded that the reason must have been the existence of both the saw-tooth bottom section of the dive and pre-dive exercise. There were two others on the dive with me, with the same profile, who had no issue.
After minutes on O2 at 2.8 bar in the chamber, all bad sensation in my arm had gone leaving me to conclude that it must have been DCS and I had a further 5 hours to think about just what implications this now had upon my diving and my career. I know plenty of people in all parts of the industry across the world that have been bent to some degree (thankfully no serious cases) at various times in the past. Still, I did struggle to accept that it had actually happened to me given the meticulous way with which I typically conduct all dives I perform.
Due to the speed with which the symptoms disappeared in the chamber and their severity prior to it, the hyperbaric doctor prescribed no diving for 4 weeks with a followup then to ascertain whether diving could commence. With my frustration, I followed this advice exactly and 4 weeks later was absolutely fine and signed off for diving. Shallow, no-deco dives to begin with of course but happily upon beginning technical dives once more after a safe period, I had no repeat hits. A big relief for sure.
Approximately a month ago, I was again on a 40m dive with minimal deco obligation (final dive of Tec40 course), in twinset air + 50% and the exact same sensation returned again. I was horrified. The dive profile was perfect, very conservative, great conditions, I was well hydrated and I had done no exercise. Since the first incident however, I had read plenty of material and before sending myself off to the chamber this time I decided to take some muscle relaxants and head home to rest and continue hydrating. There was certainly an improvement, pain disappeared, still a bit numb but nothing that concerned me. I went to sleep.
In the morning I woke feeling fine but within minutes of getting out of bed, the pain and numbness intensified again. Feeling experimental, with nothing to do, I went to the dive shop, put myself on O2 and waited for 45 minutes. There was a drastic improvement again, I took anti-inflammatories and went home to rest for the day. The next day I was also dry and felt fine. Must be a muscular issue. The following day I was in the water at 5m teaching a sidemount course and after the dive, back came the same sensation.
Logic tells you that there is no way you can get hit at 5m...unless of course you have just been hit a few days prior and the tissue is severely damaged. The mind plays many tricks upon you in such a situation and I decided to be sensible and phone DAN. The DAN doctor, rather hurriedly informed me that if medication made the pain subside it wasn't DCS. I went to sleep. The next day it was worse, very numb, tingles in my hand, slight throbbing sensation. So back to the local doctor I returned, another neuro and physical and he confirmed no DCS, just a muscular issue, rest and continue anti-inflammatories, muscle relaxants and allow recovery.
I stayed dry for two weeks, in some sense actually fearing returning to the water in case of another episode. Finally I forced myself to ignore my internal mind games, enter the water and confront it. All was absolutely fine. Back to my normal diving schedule. Fast forward to two days ago and I am doing a 55m training dive, twinset, trimix, two decos, 80 minute dive time with a lot of swimming. Once again the same situation happens, 10-15 minutes after the dive, intensifying over time. This time I wasted no time in taking some fairly strong muscle relaxants and anti-inflammatories with a large amount of water while doing a classroom theory session. By the evening my arm was 100% ok. The following day we did 65m to finish a Tec65 course which went perfectly, and all was ok after the dive.
Finally I arrive at my learnings from the last few months. While I will never know for certain, I strongly believe that I was never bent in the first place. I think that something about being in a twinset combined with my trim posture during deco pinches a nerve and creates symptoms that can be confused with a type I hit. Breathing 100% O2 probably does help the issue as I am in a relaxed posture while on it. I have spoken to some during this time that have, based on their own experience, said that a DCS hit really, REALLY hurts and that the description of my symptoms does not sound extreme enough.
Still, it is a tough sitution to be in. I consider myself to have a very high knowledge of dive physiology and decompression theory and practice, though when faced with potential symptoms, erring on the side of caution that first time was certainly a sensible idea. From the doctor's perspective as well, given that I was full DAN insured, he was maybe erring on the side of caution by putting me in the chamber also. In summary, there are a few things that I take from my experiences:
- A trapped nerve can produce symptoms very similar to that of type I DCS
- Whether at fault or not, a saw-toothed profile between 40m and 30m is still to be avoided
- Keep the bodyweight exercises away from deep dives regardless
- If the sensation of a possible hit is minor, perhaps muscle relaxants / anti-inflammatories should be tried first and a self-assessment made (MY OWN GUIDANCE, NOT ADVICE I AM PRESCRIBING TO ALL, I AM NOT A QUALIFIED DOCTOR)
- If medications cause symptoms to subside, it probably isn't DCS (as confirmed by DAN doctor over the phone, but still DO NOT TAKE AS GUARANTEED, SEEK YOUR OWN MEDICAL ADVICE).
I hope my account provides some amount learning. Ultimately of course, I would advise any diver to have a comprehensive insurance cover so that if you ever question yourself or someone else having DCS, you immediately take appropriate action (lay down, breath 100% O2) and get yourself to emergency medical/hyperbaric care. Being in the chamber is not a fantastic experience, and there are certainly considerations that should be made about going there, but let the hyperbaric professionals make that assessment and feel safe in the knowledge that if it does have to happen, your insurance is there to cover the financial aspect. I know that in my case, my DAN coverage was invaluable. I had a single accident report to fill in, and then the rest was handled entirely between DAN and the hyperbaric chamber.
Thank you for listening ;-)
to intense toothache-type pain. Most typically, it is described as a dull, deep & throbbing sensation that can be mild at onset and gradually become worse. 
