AVIA 300: Trapped Gas & Evolved Gas in Humans

Flashcards covering key vocabulary, definitions, and concepts related to trapped gas and evolved gas in the human body during aviation, including various barotraumas and types of decompression sickness.

Trapped Gas

Any volume of gas in a human body unable to equalize with ambient atmospheric pressures, which expands and compresses due to Boyle's law.

Boyle's Law

As the pressure on a gas increases, the volume of the gas decreases because the gas particles are forced closer together (and vice versa).

Barotitis Media (Otic Barotrauma)

A common problem in the middle ears during descent, also known as an ear block, where pressure equalization is difficult due to trapped gas.

Valsalva Maneuver

A clearing method for ear blocks involving exhaling forcibly with the mouth closed and nose pinched, used to equalize pressure in the middle ear.

Barosinusitis

Pain in the sinuses caused by trapped gas, typically experienced during descent from altitude or when moving from a low-pressure to a higher-pressure environment.

Barodontalgia

Tooth pain caused by an air pocket trapped within a tooth, which expands with changes in pressure, often felt as if the tooth is being squeezed.

GI Barotrauma

Discomfort or pain in the gastrointestinal (GI) tract due to gas expansion when ascending to a higher altitude.

Pulmonary Barotrauma

Tearing of lung tissue due to rapid descent and the resulting amount of air and pressure in the lungs, occurring when the descent reaches incredible speeds (e.g., a pressure differential of 10-psi or more within 0.1-0.5 seconds).

Caisson Disease

The historical term for decompression sickness, first noticed by caisson workers experiencing physical problems from pressure changes.

Henry's Law

The amount of gas dissolved in a solution is proportional to the partial pressure of that gas over the solution.

Decompression Sickness (DCS)

A condition resulting from evolved gas (primarily nitrogen) forming bubbles in body tissues and fluids, typically occurring during exposure to altitude or ascent from depth.

Nitrogen Bubbles

Formed when nitrogen, dissolved in body fluids and tissues at pressure, comes out of solution and creates bubbles as pressure decreases.

R-value

A risk value for Decompression Sickness (DCS), calculated as the ratio of nitrogen saturation level (PN2) to exposed atmospheric pressure (PB), where 1.5 or greater indicates increased risk.

Type 1 DCS

A type of Decompression Sickness primarily affecting musculoskeletal and skin systems, including Bends and Cutaneous symptoms.

Type 2 DCS

A more severe type of Decompression Sickness affecting neurological and circulatory systems, including Central Nervous System (Neurologic) and Chokes (Cardiopulmonary) symptoms.

Bends (Arthopathy)

The most common form of DCS, characterized by localized, deep pain, typically in large joints, caused by negative pressures.

Cutaneous DCS ('The Creeps')

A rare type of DCS where nitrogen bubbles form under the skin, causing symptoms like itching, tingling, hot/cold sensations, or a red blotchy rash.

Central Nervous System (Neurologic) DCS

A severe and rare form of DCS where nitrogen bubbles form in brain neurons, the spinal cord, or peripheral nerves, leading to symptoms like confusion, memory loss, vertigo, or unconsciousness.

The Chokes (Cardiopulmonary DCS)

A rapidly fatal form of DCS where nitrogen bubbles in the lungs prevent normal oxygen transfer, causing a burning sensation under the sternum, a dry cough, and a feeling of suffocation.

De-nitrogenation

A prevention method for DCS involving pre-breathing 100% oxygen to purge excess nitrogen from the body before altitude exposure.