6-7
foods as tolerated.
Prevention and Hygiene: Follow decompression tables, stay fit, avoid alcohol, avoid trauma, limit medica-
tions. Patient should remain at recompression chamber facility for 6 hours, and be within one hour of chamber
for 24 hours following recompression treatment in case further treatment is needed.
No Improvement/Deterioration: Return for immediate re-evaluation.
Follow-up Actions
Return evaluation: If residual symptoms are present, additional recompression treatments may be performed
AFTER consult and approval from a Diving Medical Officer (DMO).
Consultation Criteria: DMO should be consulted immediately after a dive injury is identified. Any residual
symptoms should be discussed with a DMO and appropriate medical specialist (i.e., neurologist).
Evacuation: As soon as patient is stable. Comply with warnings about altitude.
Dive Medicine: Pulmonary Over Inflation Syndrome
(Including Arterial Gas Embolism)
CPT Jeffrey Morgan, MC, USAIntroduction: Pulmonary Over Inflation Syndrome (POIS) results typically from gas expanding in the lung as
a diver ascends from depth without exhaling. The expanding gas ruptures lung and vascular tissues. Gas
can then enter the pleural space (pneumothorax), mediastinum (mediastinal emphysema), pulmonary venous
system (creating emboli) and other tissues. The pulmonary venous emboli return to the left heart, enter
the arterial system (arterial gas embolism [AGE]), travel anywhere in the body, block blood flow and cause
ischemia. The central nervous system (CNS) and the heart are most susceptible to serious injury from
localized hypoxia due to an AGE. As a basic rule, any diver who has obtained a breath of compressed gas
at depth from any source, whether diving apparatus or diving bell, and who surfaces unconscious or loses
consciousness within 10 minutes of surfacing, must be assumed to be suffering from an AGE.
Subjective: Symptoms
Symptoms: Sudden onset CNS symptoms are most common and include: dizziness, limb weakness or
paralysis, hemiparesis, numbness, mental status changes, loss of consciousness, confusion, tingling, poor
coordination, ataxia, difficulty speaking, visual disturbances, convulsions, personality changes, urinary reten-
tion, abdominal complaints of nausea and/or vomiting. Virtually any CNS symptom may be associated with an
AGE. Symptoms of other POIS conditions may also be seen.
Focused History: How long after surfacing did the symptoms start? (AGE symptoms usually manifest while
surfacing or within 10 minutes of surfacing from a dive.)
Objective: Signs
Using Basic Tools:
Follow the neurological examination checklist from the US Navy Dive Manual in Handbook Appendix.
Neurological: Numb to: Light/deep touch, pain/temperature, proprioception, vibration, two-point tactile
discrimination; decreased strength or paralysis, including hemiparesis or hemiplegia; diminished reflexes;
decreased mental functioning.
Cardio-pulmonary symptoms: Tracheal deviation, respiratory distress; blood in sputum, EKG changes
(4-5%), cardiac arrest, crackles in lungs, decreased breath sounds, tympanic areas in thorax.
Using Advanced Tools: CXR if available to assess for POIS (pneumothorax, air in mediastinum or other
tissues).
Assessment:
Differential Diagnosis: Decompression sickness (‘the bends’), hypoxia, carbon monoxide poisoning and
other diving causes, as well as non-diving causes, including hypoglycemia, seizure, near drowning and
myocardial infarction.