DIVING

Appendix F. Glossary
Paraparesis
Partial paralysis of the lower limbs.
Paresthesia
Numbness or tingling of the skin; a common symptom of
DCS in recreational divers.
Partial Pressure
The pressure exerted by a single component gas, typically
in a mixture of gases.
Patent Foramen Ovale (PFO)
An opening between the right and left atria of the heart.
Normally closed and sealed by tissue growth after birth,
almost 30% of the adult population retain some degree of
patency (openness). ‘Probe patency’ describes the ability
to work a blunt probe through the opening during autopsy.
Such openings may be small and functionally irrelevant.
‘Physiologic patency’ describes an opening large enough
to allow meaningful flow of blood directly between the two
chambers. A small portion of those with a PFO will have the
highest degree of patency. Blood passing from right to left
through a PFO bypasses lung filtration. Any bubbles present
in such blood would be distributed throughout the body,
potentially increasing the risk of serious decompression
sickness if the bubbles impinged upon sensitive tissues.
Some divers investigate the option of medical closure of
PFOs. The risk of PFO in divers can also be mitigated by
conservative dive profiles that do not produce bubbles.
Paua
A large, edible abalone found in New Zealand.
Perceived Severity Index (PSI)
A measure of the severity of decompression injury.
Pleural Space
The small potential space between the parietal and visceral
layers of the pleura that lines the thoracic cavity. It is a
potential space since there is no actual space, instead it
is filled with a lubricating fluid that reduces the friction between
the pleural layers as the lungs expand and contract.
Pneumomediastinum
See “Mediastinal Emphysema.”
Pneumothorax
A collection of gas in the pleural space (the fluid-filled potential
space surrounding the lungs), which results in the
collapse of the lung on the affected side.
Project Dive Exploration (PDE)
A long-term study developed by DAN to collect computerized
profiles of diving exposures and information on the
health outcome (symptomatic or asymptomatic). The accumulated
data can be useful to model decompression risk.
Protected Health Information (PHI)
Information that could disclose the identity of a research
subject, patient or decedent according to the Health Insurance
Portability and Accountability Act (HIPAA). PHI
includes names, address, birthdate, social security numbers,
etc. DAN does not disclose PHI to any party other
than employees, representatives and agents of DAN who
have a need to know.
Pulmonary Barotrauma (PBT)
Damage to lungs from expanding gas. See “Barotrauma.”
Pulmonary Emphysema
A medical condition commonly caused by smoking that
leads to abnormal distension of the lungs resulting from the
destruction of its supporting and elastic internal structure.
Pulmonary Overinflation Syndrome (POIS)
A group of barotrauma-related diseases caused by the expansion
of gas trapped in the lung, or over-pressurization
of the lung with subsequent over-expansion and rupture
of the alveolar air sacs. It includes arterial gas embolism,
tension pneumothorax, mediastinal emphysema, subcutaneous
emphysema and rarely pneumopericardium.
Pulmonary Overexpansion
Abnormal distension of the lungs. In divers, pulmonary
over- expansion usually results from the effects of Boyle’s
law. It can cause rupture of alveoli and penetration of gas
into various surrounding spaces, causing mediastinal emphysema,
pneumothorax or arterial gas embolism. See
“Pulmonary barotrauma.”
Rales
Wet, clicking, rattling or crackly lung noises heard on auscultation
of (listening to) the lung during inspiration. The
sounds are caused by the opening of small airways and
alveoli collapsed by fluid in the air spaces.
Rapid Ascent
An ascent rate fast enough to put a diver at increased risk
of decompression illness (DCI), usually at rates in excess
of 60 fsw (18 msw) per minute.
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Annual Diving Report – 2012-2015 Edition