Certain emergencies, such as uncontrolled ascents, an exhausted air supply, or
bodily injury, may interrupt or prevent required decompression. If the diver shows
symptoms of decompression sickness or arterial gas embolism, immediate treatment
using the appropriate oxygen or air recompression treatment table is
essential. Even if the diver shows no symptoms, omitted decompression must be
addressed in some manner to avert later difficulty. Table
21-3 summarizes
management of asymptomatic Omitted Decompression.
Planned and Unplanned Omitted Decompression. Omitted decompression may
or may not be planned. Planned omitted decompression results when a condition
develops at depth that will require the diver to surface before completing all of the
decompression stops and when there is time to consider all available options,
ready the recompression chamber, and alert all personnel as to the planned evolution.
Equipment malfunctions, diver injury, or sudden severe storms are examples
of these situations. In unplanned omitted decompression, the diver suddenly
appears at the surface without warning or misses decompression for some unforeseen reason. In either instance, the Surface Decompression Tables may be used to
remove the diver from the water, if the surfacing time occurs such that water stops
are either not required or have already been completed. When the conditions that
permit using the Surface Decompression Tables are not fulfilled, the diver’s
decompression will be compromised. Special care shall be taken to detect signs of
decompression sickness. The diver must be returned to pressure as soon as
possible.
Treating Omitted Decompression with Symptoms. If the diver develops symptoms
of decompression sickness during the surface interval, treat in accordance
with the procedures in paragraph 21-4 (no chamber available) or paragraph
21-5
(chamber available). If the diver has no symptoms of decompression sickness or
arterial gas embolism, make up the omitted decompression as described in
this section.
Treating Omitted Decompression in Specific Operational Environments. Refer
to paragraph 17-10.6 for procedures for dealing with omitted decompression
during MK 16 diving operations. Refer to paragraph 14-4.10 for procedures for
dealing with omitted decompression during surface-supplied helium-oxygen
diving operations.
Ascent from 20 Feet or Shallower (Shallow Surfacing) with Decompression
Stops Required. If the diver surfaced from 20 feet or shallower, feels well, and
can be returned to stop depth within 1 minute, the diver may complete normal
decompression stops. The decompression stop from which ascent occurred is
lengthened by 1 minute. If the diver cannot be returned to the depth of the stop
within 1 minute and the diver remains asymptomatic, return the diver to the stop
from which the diver ascended. Multiply each decompression stop time missed by
1.5. Alternatively, if the surface interval is less than 5 minutes, the diver may be
placed in a recompression chamber and treated on a Treatment Table 5 (or 1A if
no oxygen is available). If the surface interval is greater than 5 minutes, the diver
may be placed in a recompression chamber and treated on Treatment Table 6 (or
2A if no oxygen is available). The diver should be observed for 1 hour after
surfacing and/or completing treatment.
Ascent from 20 Feet or Shallower with No Decompression Stops Required. No
recompression is required if the diver surfaces from 20 feet or shallower but was
within no-decompression limits. The diver should be observed on the surface for 1
hour.
Ascent from Deeper than 20 Feet (Uncontrolled Ascent). Any unexpected surfacing
of the diver from depths in excess of 20 feet is considered an uncontrolled
ascent. If the diver is within no-decompression limits and asymptomatic, he
should be observed for at least 1 hour on the surface. Recompression is not necessary
unless symptoms develop.
Asymptomatic Uncontrolled Ascent. Asymptomatic divers who experience an
uncontrolled ascent and who have missed decompression stops are treated by
recompression based on the amount of decompression missed as follows:
-
Oxygen Available. Immediately compress the diver to 60 feet in the recompression
chamber. If less than 30 minutes of decompression (total ascent time
from the tables) were missed, decompress from 60 feet on Treatment Table 5.
If more than 30 minutes of decompression were missed, decompress from 60
feet on Treatment Table 6.
-
Oxygen Not Available. Compress the diver to 100 feet in the recompression
chamber and treat on Table 1A if less than 30 minutes of decompression were
missed; compress to 165 feet and treat on Table 2A if more than 30 minutes
were missed.
Development of Symptoms. As long as the diver shows no ill effects, decompress
in accordance with the treatment table. Consider any decompression sickness that
develops during or after this procedure to be a recurrence. Try to keep all surface
intervals as short as possible (5 minutes or less). If an asymptomatic diver who has
an uncontrolled ascent from a decompression dive has more than a 5-minute
surface interval, recompress to 60 feet on Treatment Table 6 or treat on Table 2A,
even if the missed decompression time was less than 30 minutes.
In-Water Procedure. When no recompression facility is available, use the following
in-water procedure to make up omitted decompression in asymptomatic
divers for ascents from depths below 20 feet.
Recompress the diver in the water as soon as possible (preferably less than a 5-
minute surface interval). Keep the diver at rest, provide a standby diver, and maintain
good communication and depth control. Use the decompression schedule
appropriate for the divers depth and bottom time. Follow the procedure below with
1 minute between stops:
1. Return the diver to the depth of the first
stop.
2. Follow the schedule for stops 40-fsw and deeper.
3. Multiply the 30-, 20-, and 10-fsw stops by 1.5.
Symptomatic Uncontrolled Ascent. If a diver has had an uncontrolled ascent and
has any symptoms, he should be compressed immediately in a recompression
chamber to 60 fsw. Conduct a rapid assessment of the patient, and treat accordingly.
Treatment Table 5 is not an appropriate treatment for symptomatic
uncontrolled ascent. If the diver surfaced from 60 fsw or shallower, compress to
60 fsw and begin Treatment Table 6. If the diver surfaced from a greater depth,
compress to 60 fsw or depth where the symptoms are significantly improved, not
to exceed 165 fsw, and begin Treatment Table 6A. Symptoms developing during
the surface interval or during a period of observation on no-decompression dives
are treated as described in paragraph 21-5 (reference Table 21-3). Consultation
with a Diving Medical Officer should be made as soon as possible. For uncontrolled
ascent deeper than 165 feet, the diving supervisor may elect to use
Treatment Table 8 at the depth of relief, not to exceed 225 fsw.
Treatment of symptomatic divers who have surfaced unexpectedly is difficult
when no recompression chamber is on site. Immediate transportation to a recompression
facility is indicated; if this is impossible, the guidelines in paragraph 21-4
may be useful.
