Descriptions for terms used within the filtration and humidification landing page.

Absolute Humidity (AH) The mass of water vapour present in a given volume of air, typically expressed in grams per cubic metre (g/m³).
Alveoli Microscopic air sacs in the lungs that provide a large surface area for gas exchange with the blood.
Artificial airway A medical device inserted into the upper or lower respiratory tract to maintain airway patency, facilitate ventilation, and/or allow suctioning of secretions.
Atelectasis Partial or complete collapse of alveoli resulting in reduced or absent gas exchange in part of the lung.
Bacteria Single-celled microorganisms that lack a true nucleus. They can live independently or reproduce on their own, and while many bacteria are harmless or beneficial, some can cause disease.
Barotrauma Physical damage to body tissues caused by a difference in pressure between a gas-filled space inside the body (like the ear, lungs, or sinuses) and the surrounding air or water.
Capillaries Fine branching blood vessels that form a network between the arterioles and venules.
Cardiac output The total volume of blood the heart pumps per minute, calculated by multiplying heart rate by stroke volume.
Carina A cartilage situated at the point where the trachea divides into the two bronchi.
Cilium/Cilia Short, microscopic hair-like vibrating structure found in large numbers on the surface of cells in the upper airways.
Electrostatic media Web of polypropylene fibers with an electrostatic charge. These positive and negative charges enhance the filter's ability to trap microbial contaminants whilst maintaining a relatively low resistance to flow.
Efficiency The quantitative measure of a filter's ability to remove contaminants from a fluid stream (liquid or gas) typically expressed as a percentage of contaminants removed.
Hepatitis C A viral infection caused by the HCV virus that triggers inflammation of the liver, leading to potential long-term damage like cirrhosis or liver cancer. 
HIV (Human Immunodeficiency Virus) A virus that attacks the body’s immune system reducing the body's ability to fight infections, potentially leading to AIDS (Acquired Immunodeficiency Syndrome).
Humidification The process of adding water vapor (and often heat) to inspired gases to maintain the required moisture levels in the respiratory tract.
Hydrophobic A natural resistance to water/fluid.
Intrathoracic Located, occurring, or functioning within the thoracic cavity (the chest).
Mechanical dead space The volume of an artificial breathing system that contains air that has been previously exhaled and does not participate in gas exchange.
Microbial Anything relating to, caused by or consisting of microorganisms. Infections, agents, or ecosystems that can either cause disease or play essential roles in health, such as digestion.
Mucus membranes Protective linings covering body cavities and canals that connect to the outside environment, such as the respiratory tracts.
Nosocomial An infection acquired by a patient during the process of care in a hospital or healthcare facility.
PEEP (Positive End-Expiratory Pressure) Maintenance of pressure in the airways above atmospheric level at the end of exhalation.
Pharynx Muscle-lined tube connecting the nasal cavity and mouth to the larynx and esophagus that transports air.
Pulmonary oedema Excess fluid accumulation in the lung tissue and air sacs (alveoli), resulting in impaired gas exchange and severe respiratory distress.
Relative Humidity (RH) The amount of water vapor present in the air expressed as a percentage of the maximum amount needed to achieve saturation at the same temperature.
Resistance The frictional opposition encountered by gas during inhalation and exhalation.
Tidal volume The volume of air that is inhaled or exhaled during a single, normal, resting respiratory cycle.
Tracheostomy The result of a tracheotomy, a surgical procedure creating an opening (stoma) in the anterior neck into the trachea (windpipe) to establish a direct, stable airway.
Viruses A submicroscopic infectious agent that replicates only inside the living cells of an organism.
Work of Breathing (WOB) The energy and muscular effort required to move gas in and out of the lungs. This can be increased by obstructive diseases such as asthma and COPD. 

 

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