Page 56 - JSOM Summer 2025

1
dive. As a safety precaution, divers must continuously breathe Decompression Sickness: Treatment
out as they ascend from depth. Treatment for type I DCS varies by severity. According to the
U.S. Navy treatment tables, type II DCS is treated with 100%
POIS includes AGE, pneumothorax, and mediastinal or sub- oxygen and immediate recompression. Recompression involves
1
cutaneous emphysema. In addition to not exhaling during the taking a diver back to “depth” under pressure (hyperbaric) to
ascent, these injuries can also occur in individuals with asthma increase the partial pressure of oxygen (PO ) at treatment depth,
2
or chronic obstructive pulmonary disease, which causes air thus increasing the oxygen gradient and pulling nitrogen (N )
2
trapping and local pulmonary obstructions. This overinflation out of the system, followed by slow ascension with safety stops
can lead to AGE, which may include apnea, unconsciousness, to prevent bubble formation in the bloodstream and tissues.
seizure, vertigo, sensory changes, confusion, loss of coordina- This can be done at depth or out of water in a hyperbaric cham-
tion, visual changes, weakness, numbness, and/or convulsions, ber, although chamber recompression is preferred. Recompres-
7
which can manifest within minutes of surfacing. This was ev- sion should be done as quickly as possible, as delays of over 24
3
ident in case 1, where the patient began developing symptoms hours are associated with a far higher rate of residual symptoms
13 minutes after surfacing. after recompression therapy. As seen in Figure 2, the U.S. Navy
8
Diving Manual has a series of treatment tables that describe
Treatment for POIS includes 100% oxygen, basic first aid, and indications and treatment strategies for injured divers using hy-
6
immediate recompression as necessary. Application of Ad- perbaric chambers to achieve recompression. 1
vanced Cardiac Life Support protocols, needle chest decom-
pression, and tube or open thoracostomy may also be required The preferred method for out-of-water recompression is the
to treat POIS. The best strategy is POIS prevention, which dual-lock/multi-place recompression chamber (Figure 4). This
1
highlights the importance of well-trained and calm divers who chamber allows inside tenders to be changed out if needed and
do not panic and continually exhale during ascent. Equally im- allows supplies larger than the med-lock to be locked into the
portant is the diver’s need to report any current illness or med- treatment lock. Unfortunately, these are located at fixed facil-
ical conditions to a dive supervisor before diving (Figure 1). ities across the country and are not transportable. There are
many occasions where dive operations occur in austere envi-
FIGURE 1 Decompression illness (DCI) diving maladies separated ronments or remote locations. In these cases, time to a certified
by type.
recompression chamber may exceed 12 hours, so the Trans-
portable Recompression Chamber System (TRCS) or Stan-
Pulmonary Overinflation Syndrome Decompression Sickness
“POIS” “DCS” dard Navy Double Lock (SNDL) containerized recompression
chambers are forward deployed to afloat staging bases and
Arterial Gas Simple Mediastinal Type 1 Type 2 shore installations. In instances where it is not possible to
Embolism Pneumothorax Emphysema
“AGE” secure a TRCS or SNDL due to the urgency/security of the
mission or lack of regional sites, the portable and deployable
Pain Only Neurological
Tension Subcutaneous emergency evacuation hyperbaric stretchers (EEHS, Figure 3)
Pneumothorax Emphysema
may be used as a single-person emergency transport tool for a
Lymphatics Inner Ear
diver who requires immediate emergency recompression.
Cutis Cardio
Marmorata Pulmonary Military divers use the U.S. Navy Diving Manual to determine
how deep and long their dives can be. The dive tables within
this text prescribe how long a diver may stay at a certain depth
Decompression Sickness: Types and Symptoms before needing to surface and if they need to conduct a de-
DCS is the other subset of DCI. DCS is caused by the buildup of compression stop along the way (Figure 5). A recompression
inert gasses, primarily nitrogen, which creates bubbles within a stop would be a prescribed period of time stopped at a spe-
3
diver’s tissue or vasculature. This phenomenon can best be un- cific depth to off-gas inert gasses before continuing the ascent
derstood by an application of Henry’s law, whereby the amount to the surface. There are no-decompression tables for many
1
of dissolved gas in a liquid is directly proportional to the partial depths, decompression tables at various depths, repetitive dive
pressure of that gas. Thus, gasses are absorbed into body tissue tables, and tables for different air mixes such as air, 100% O ,
2
more quickly at an increased depth due to increased pressure. or nitrox. These tables were first developed by the U.S. Navy
DCS is a byproduct of the dive depth and duration of time in 1915 and have been regularly updated and expanded upon
spent at depth. As a diver ascends, pressure decreases, which based on new evidence and advances in diving. 9
results in the release of inert gas from the blood, causing DCS.
Medical Dive Clearance
DCS is further subclassified as type I and type II. Type I DCS Underwater diving is not without significant risks. For these
is generally less severe and involves the skin, lymphatic system, reasons, medical dive clearance is warranted in civilian and
muscles, and joints. Type II DCS can be life-threatening and af- military environments. Diving, even at shallow depths, puts
fects the nervous system, respiratory system, or cardiovascular severe stress on the respiratory system, cardiovascular system,
system . The signs and symptoms of DCS depend on the type. and middle ear, so medical providers who are certifying divers
1
Type I DCS symptoms may include burning of the skin or rash, should have a modicum of knowledge on the topic. 10
swollen lymph nodes, and/or joint pain (usually unilateral and
only one joint). Type II DCS symptoms vary based on the body For civilian recreational diving, clearance can be completed by
system affected, which may include blindness, dyspnea, hy- any medical provider. In 2020, the World Recreational Scuba
poxia, paralysis, chest pain, and ear pain, among others. Type Training Council endorsed a new medical screening system
1
II DCS symptoms may be delayed and occur from minutes af- for recreational scuba diving and freediving. This system has
11
ter surfacing to a few days after the dive. 1 three tiers, the first of which is a participant questionnaire.
54 | JSOM Volume 25, Edition 2 / Summer 2025