Preventing Decompression Illness Using the Right Table

By Joseph Walker, J.D.

I recently represented a diver who suffered neurological injury caused by multiple dives with untreated omitted decompression.

Without getting into all of the various complexities of these dives, it was also apparent that the diving contractor was still utilizing the Navy Revision 5 (Navy Rev. 5) manual for its air in water decompression. This manual was still being utilized in the field by this particular contractor as of 2017. After further investigation, I was surprised to discover that other contractors are still using the Navy Rev. 5 manual for their in water decompression as of the date of this article.

The Navy Revision 6 (Navy Rev. 6) was formally issued on April 15, 2008. It superseded Navy Rev. 5, dated August 2005. Navy Rev. 6 represented the largest changes in diving procedures since 1956 as the Navy made major changes to its decompression procedures using air and/or oxygen.

The Prologue to Navy Rev. 6 is particularly informative. It indicates that three events caused the Navy to revisit and change the 1956/1957 Air Tables:

  1. Unacceptable rates of Decompression sickness while using the Revision 5 “Air Tables” and Sur-D-02 Tables at selected depths above 100 feet.
  2. Commercial dive practices migrated from Revision 5 “Air Tables” due to unacceptable rates of decompression sickness at long endurance/ shallow depth dives.
  3. The seminal research into Hyperbaric medicine led by Dr. Edward D. Thiemann, Captain, MC, USN (deceased) applying the selection of the Thiemann Algorithm as the basis of the new Revision 6 “Air Table.”

In a nutshell, the changes in Navy Rev. 6 “Air” in water decompression are significant as they eliminated the 10 foot stop by changing the last stop to 20 foot and they added in water decompression for dives that had previously required either no in water decompression or short duration water stops. For diving modes requiring long duration shallow dives such as hull cleaning and salvage operations, these changes are nothing short of radical. Navy Rev. 6 also modified the Sur-D-02 tables to add a 15-minute stop at 50 feet in the Chamber, increased O2 time at 40 ft. and reduced the number of in water stops. In contrast to most commercial diving manuals, the Navy still uses a one-minute slide from 40’ to the surface. Navy Revision 7 (Navy Rev. 7) was issued 12/01/2016 but did not change the decompression schedules issued in Navy Rev. 6.

The following is a comparison of actual dives incorrectly run using the outdated Navy Rev. 5 in lieu of Revision 6 (now Navy Rev. 7). The comparisons are significant.

Applying the proper protocol using the existing navy rev. 6 this dive had 17 minutes of omitted decompression at 20’.
Applying the proper protocol using the existing navy rev. 6 this dive had 2 minutes of omitted decompression at 20’.
Applying the proper protocol using the existing navy rev 6 this dive had 52 minutes of omitted decompression at 20’ of critical importance, each of the above dive profiles which were run on the Navy Rev. 5 tables rather than using the Navy Rev. 6 tables had, by omission, significant omitted decompression.

Applying Rev. 6 an immediate DCS (Decompression Sickness) treatment protocol should have been initiated for omitted decompression, irrespective of whether the diver was asymptomatic (i.e., had no complaints). Neurological signs/symptoms of DCS can go unnoticed by the diver, as these signs/symptoms are often subtle and often ascribed to other causes such as unusual fatigue, confusion, malaise and personality changes.

You can’t expect a diver suffering from brain injury to self-diagnose brain injury.

It’s not uncommon for divers following hard working long duration shallow dives to experience joint soreness, fatigue, malaise and other subtle symptoms of DCS, which divers will ascribe to the rigors of the dive especially if the dive is within the no decompression limits or the prescribed water stops have been completed.

” … Most DCS manifests itself subtly with a minor joint pain or a parasthesias (an abnormal sensation like burning, tingling or ticking) in an extremity. In many cases these symptoms are ascribed to another cause such as overexertion, heavy lifting or even a tight wetsuit. This delays seeking help and is why the first symptom of DCS is denial. Sometimes these symptoms remain mild and go away by themselves but many times they increase in severity until it is obvious to you (diver) that something is wrong and that you need help… mild symptoms may be ascribed to causes other than the dive, which only delays treatment. Sometimes these symptoms may resolve spontaneously and the diver will not seek treatment. The consequences of this are similar to untreated DCS residual damage to the brain may occur… Dr. E.D. Thalmann

It’s not uncommon for divers following hard working long duration shallow dives to experience joint soreness, fatigue, malaise and other subtle symptoms of DCS.

Also of critical importance, the Navy Rev. 6 also breaks its decompression table in 5 foot increments between 30’ and 60’. The changes to these shallow tables are dramatic and obviously were made to address the concerns raised about unacceptable rates of DCS in long endurance shallow dives and selected ranges above 100 feet.

By way of example, the 40 foot schedule illustrates the significant modification and more conservative decompression times than what was previously used in Navy Rev. 5.

40 Ft. Decompression Schedule.

Based on the above it should be incumbent on diving contractors and diving personnel undertaking both search and rescue and scientific operations alike to immediately review their existing manuals and at least replace their in water decompression tables with the Navy Rev. 7. Additionally, diving contractors should address the diving mode and should either consider increasing the dive teams or opt to use the Sur-D-O2 tables rather than subjecting the diver to long in water decompression times as required by Navy Rev. 6 (Now Navy Rev. 7). The consequences of not doing so could result in irreparable harm to the diver and serious legal consequences.

Joe Walker is a maritime attorney at Franklin, Mosele & Walker, P.C. in Houston, Texas, a former saturation diver with Solus Ocean Systems, and VP at Oceaneering International Asia Pacific Division.

Practicing maritime law for over 25 years, Joe brings a wealth of working knowledge to the courtroom and understands the complex risk factors inherent to offshore work.

Joe has spent decades devoting his time and efforts towards diving safety, with a particular emphasis on the use of hyperbaric oxygen therapy (HBOT) for the treatment of post-acute decompression illness, traumatic brain injury, and organic brain injury.

He has worked closely with prominent HBOT physicians to develop protocols for the use of HBOT for his injured clients.