Medical Services
Diving Medical Dictionary

| A | B | C | D | E | F | G | H | I | J | K | L | M |
| N | O | P | Q | R | S | T | U | V | W | X | Y | Z |

-- A --

Alveoli -- Microscopic air sacs in the lungs where gas exchange occurs with the circulatory system.

Anoxia -- Absence of oxygen in the circulating blood or in the tissues.

Aorta -- The largest vessel of the systemic arterial system, from which the main arteries carrying oxygenated blood branch and subdivide into smaller and smaller vessels.

Arterial Gas Embolism -- Also referred to as AGE, a condition in which gas bubbles enter the arterial system and cause damage by blocking blood flow to vital organs, most commonly the brain. This is generally caused by air passing through the walls of the alveoli into the bloodstream.

Arteriole -- Small artery.

Atrium -- Chamber of the heart which provides access to another chamber called the ventricle.

-- B --

Bronchi -- Plural of bronchus, which is a division of the trachea.

Bronchiole -- Small branch of the bronchus that carries air to and from the alveoli.

Bronchospasm -- Bronchoconstriction, or the sudden narrowing of the smaller airways, of a spasmodic nature.

Buoyancy Control -- The ability to maintain neutral buoyancy. Common causes of buoyancy problems include a current pushing a diver either up or down, being either over- or under-weighted, overinflation of the buoyancy compensator, or lack of the actual skill.

-- C --

Capillary -- Microscopic blood vessels where the gas exchange takes place between the bloodstream and the tissues or the air in the lungs.

Carbon Dioxide -- A waste gas produced by the metabolism of oxygen in the body.

Carbon Monoxide -- A highly poisonous, odorless, tasteless and colorless gas formed when carbon material burns with restricted access to oxygen. It is toxic by inhalation since it competes with oxygen in binding with the hemoglobin, thereby resulting in diminished availability of oxygen in tissues.

Cartilaginous -- Pertaining to or composed of cartilage.

Cilia -- Long, slender microscopic hairlike processes extending from cells and capable of rhythmic motion.

CPR -- Cardiopulmonary resuscitation.

Current -- Refers to a strong or moderate current being present in diving waters during the day of interest.

-- D --

Decompression Diving -- Diving exposure requiring staged in-water stops before ascent to the surface.

Decompression Illness -- Also referred to as DCI, decompression illness is a term to describe dysbaric injuries related to scuba diving. This diagnosis stems from the uncertainties in many cases about the mechanistic causation of neurological symptoms. Moreover, it is sometimes impossible to differentiate clinically between neurological DCS and AGE. An alternative approach has been suggested in which the clinical manifestation of a patient's decompression syndrome is described without attempting to determine the pathophysiology. The term "decompression illness" (DCI) is suggested to encompass all manifestations of diseases following a reduction in ambient pressure, such as ascending from a dive.

Decompression Sickness -- Also referred to as DCS, a syndrome caused by bubbles of inert gas forming in the tissues and bloodstream during or after ascent from a dive. DCS is manifested in two major forms, DCS I and DCS II.

  • DCS I -- Decompression sickness involving only muscle and joint pain, fatigue and/or skin symptoms (itching, rash).
  • DCS II -- Decompression sickness that includes symptoms involving the central nervous system, respiratory system or circulatory system.

Dehydration -- An abnormal depletion of water and other body fluids.

Diameter Indexing Safety System (DISS) -- Intermediate pressure port where a hose attaches, leading to demand valve or other apparatus.

-- E --

EMS -- Emergency Medical Services

Enriched-Air Nitrox (EAN) -- A nitrogen/oxygen mixture containing more than 21 percent oxygen, usually made by mixing air and oxygen.

Epiglottis -- Thin structure behind the tongue that shields the entrance of the larynx during swallowing, preventing the aspiration of debris into the trachea and lungs.

Erythroprotein -- A protein which is synthesized mainly in the kidneys and stimulates red blood cell formation.

Esophagus -- Portion of the digestive tract that lies between the back of the throat and stomach.

Exertion -- Exercise above that required for a relaxed swim in calm water. The main causes of exertion during a dive are current or extra equipment (such as for photography or specialty diving).

-- F --

Fatigue -- Complaints of being tired, experiencing a lack of sleep or a generalized tiredness.

fsw -- feet of sea water.

Fossa Ovalis -- Oval depression in the wall of the heart remaining when the foramen ovale closes at birth (See patent foramen ovale).

-- G --

Gradient -- The difference in pressure, oxygen tension, or other variable as a function of distance, time or other continuously changing influence.

-- H --

Heliox -- Helium and oxygen mixes.

Hypoxemia -- Inadequate oxygen supply in the arterial blood.

Hypoxia -- Inadequate oxygen supply to the body tissues.

-- I --

Inert -- Having little or no tendency to react chemically.

Incontinence -- Absence of voluntary control of an excretory function, especially defecation or urination.

Intercostal Muscles -- The muscles between the ribs which contract during inspiration to increase the volume of the chest cavity.

Ischemia -- Inadequate blood flow to a part or organ.

-- L --

Larynx -- The organ of voice production, also known as the voice box; the opening from the back of the throat into the trachea (windpipe).

Laryngospasm -- Severe constriction of the larynx in response to the introduction to water, allergies, or noxious stimuli.

LPM -- Liters per minute. A measurement of a flow rate of gas or liquid.

-- M --

Mediastinum -- The space within the chest located between the lungs, that contains the heart, major blood vessels, trachea and esophagus.

Metabolism -- The conversion of food into energy and waste products.

Mixed Gas -- Any breathing medium that was mixed using oxygen and other gases, most commonly, helium, nitrogen, or air. Mixed gas could have only a single inert gas (e.g., heliox, nitrox) or multiple inert gases (e.g., trimix -- nitrogen, helium and oxygen mixes: see next page).

Multiday -- When more than one day of diving was performed in this particular dive series with a surface interval of < 24 hours between consecutive dives. "Multiday" and "single-day" are mutually exclusive.

Multilevel Dive -- A dive in which the diver remains at several depths for a period of time before beginning final ascent to the surface: this contrasts with square dive, which involves a singe depth (see next page). Many different levels can be visited in one dive before finally ascending -- for example, a diver descends to 60 feet / 18 meters and stays for 10 minutes then descends to 80 feet / 24 meters and stays for five minutes, ascends to 50 feet / 15 meters for 10 minutes and then to 20 feet / 6 meters for five minutes before surfacing.

-- N --

Nitrox -- A nitrogen-oxygen mixed gas that contains an oxygen percentage other than 21 percent. "Oxygen-enriched air" or "enriched-air nitrox" refer to nitrox mixtures with oxygen levels greater than 21 percent. The most common nitrox mixtures are NOAA Nitrox I and NOAA Nitrox II, 32 percent oxygen and 36 percent oxygen, respectively.

No-Decompression -- A dive not requiring a staged stop during ascent to the surface. This type of dive can be made with either tables or computers.

Nystagmus -- Spontaneous, rapid, rhythmic movement of the eyes occurring on fixation or on ocular movement.

-- O --

Oblique -- An indirect or evasive angle.

Oxygen -- A colorless, odorless, tasteless gas essential to life making up approximately 21 percent of air.

Occlude -- To close off or stop up; obstruct.

-- P --

Patent Foramen Ovale -- A hole in the septum (wall) between the right and left atria of the heart.

Pericardium -- A double-layered membranous sac surrounding the heart and major blood vessels connected to it.

Pharynx -- Portion of the airway at the back of the throat, connecting mouth, nasal cavity and larynx.

Platelet -- A round or oval disk found in the blood of vertebrate animals that are involved with blood clotting.

Pleura -- Membranes surrounding the outer surface of the lungs and the inner surface of the chest wall and the diaphragm.

Prescription -- A written order for dispensing drugs signed by a physician.

Primary Assessment -- Assessment of the Airway, Breathing and Circulation (pulse) in an ill or injured person; also known as the ABCs.

PSI -- Pounds per square inch; a measurement of pressure.

-- R --

Rapid Ascent -- The currently recognized recommended ascent rate is no faster than 60 feet / 18 meters per minute. A rapid ascent occurs when a diver ascends faster than the recommended rate. Rapid ascents are often uncontrolled and can be caused by overinflation, poor buoyancy control, being underweighted or panic.

Repeat Dive / Repetitive Dive -- More than one dive was made on the day of interest, with some period of time spent at the surface between dives (surface interval). "Single dive" and "repeat dive" are mutually exclusive.

Respiration -- The exchange of gases between a living organism and its environment; the act of breathing.

Respiratory Arrest -- Cessation of breathing.

-- S --

Sign -- Any medical or trauma condition that can be observed and described.

Single-Day -- Only one day of diving was done in this particular dive series. "Single-day" does not denote the number of dives, but rather a single day of diving (for example: four dives could be made in a single day: or a single day of diving could include one dive only).

Square Dive -- A dive in which a diver descends to a single depth and remains until beginning the final ascent to the surface. This contrasts with multilevel dive, (see Page 123): for example, a diver descends to 60 feet / 18 meters and stays at 60 feet for 30 minutes before ascending. Square dives and multilevel dives are mutually exclusive.

Supine -- Lying flat on back, with face upward.

Surfactant -- A substance produced in the lungs to reduce surface tension in alveoli and small airways.

Symptom -- Any non-observable condition described by the patient.

-- T --

Technical Dive -- In this report, a technical dive is defined as one in which one of the following conditions existed:

  • Diving deeper than 130 feet / 40 meters;
  • Using a breathing mixture other than compressed air;
  • Decompression or overhead diving (diving in shipwrecks or caves);
  • Special training and equipment were used.

Thorax -- The upper part of the trunk (main part of the body) between the neck and the abdomen which contains the heart, lungs, trachea and bronchi.

Trachea -- The air passage that begins at the larynx and ends as the beginning of the principal right and left bronchi.

Trimix -- Nitrogen, helium and oxygen mixes.

-- V --

Valsalva Maneuver -- The forced inflation of the middle ear by exhaling with the mouth closed and the nostrils pinched.

Venous Gas Emboli -- Inert gas bubbles in venous blood (which return to the heart and lungs).

Ventricle -- Thick-walled, muscular chamber in the heart which receives blood from the atrium, pumping it through to the pulmonary or systemic circulation.

Venules -- Small veins.

-- W --

Within Limits -- represents divers who were diving within their computer or table limits.