Humidifiers - Vocabulary Flashcards (Lecture Notes)

A set of vocabulary-focused flashcards covering humidifier types, components, operation, and troubleshooting concepts from the lecture notes.

Humidifier

A device that adds moisture to the air by transforming liquid water into vapor for airway or room humidification.

Passover humidifier

A humidifier where gas passes over the surface of water; common types include simple reservoir, wick, and membrane variants.

Simple reservoir

A Passover-type humidifier configuration with a straightforward water reservoir for humidification.

Wick

A porous absorbent material in a Passover design that draws water by capillary action to humidify gas and maintain saturation with minimal aerosols.

Membrane humidifier

A Passover device that uses a hydrophobic membrane to allow vapor through while blocking liquid water, reducing aerosol spread.

Bubble humidifier

A device that bubbles gas through a water reservoir using a diffuser; increases surface area for evaporation and is commonly used with O2 therapy (not heated).

Diffuser

A component at the bottom of a bubble humidifier that breaks gas into tiny bubbles to enhance evaporation.

HME (Heat Moisture Exchanger)

A passive humidifier that captures exhaled heat and moisture and returns it to the patient; also called an artificial nose; does not add heat or water and is for short-term use (up to ~96 hours).

Artificial nose

Another name for an HME; it conserves heat and moisture during exhalation for subsequent inhalation.

Hygroscopic condenser

A condenser with low thermal conductivity impregnated with hygroscopic salt to attract moisture; about 70% efficiency.

Hygroscopic

Readily taking up and retaining moisture.

Hydrophobic condenser

A condenser using a water-repellent material with large surface area and low thermal conductivity; about 70% efficiency.

Heated systems

Humidification systems that add heat to the humidifier output, often used for bypassed airways; increases humidity but risks airway burns.

Hot plate element

A heating element located at the base of the humidifier to raise water temperature.

Wraparound element

A heating element that surrounds the humidification chamber to provide even heating.

Collar element (yolk)

A heating element around the humidifier chamber (yolk/collar) used to warm the device.

Immersion heater

A heater that sits inside the water reservoir to directly heat the water.

Heated wire on the inspiratory limb

A heating element placed along the inspiratory limb of the circuit to warm inspired gas.

Servo-controlled heating element

A feedback-controlled heater that uses a thermistor near the patient to adjust power and maintain a set airway temperature.

Thermistor

A temperature sensor used to monitor airway temperature in heated humidification systems.

Airway temperature target

Recommended airway temperature (approximately 33 ± 2°C) with a minimum of around 30 mg/L water vapor; never exceed 37°C.

Water vapor target (30 mg/L)

Minimum water vapor output guidance associated with the airway temperature target for humidification.

Reservoir

A large water container that feeds the humidifier, often manually refilled with sterile water to reduce frequent refills.

Gravity feed system

A water/feed system that uses gravity (e.g., IV bag and line) to supply water to the humidifier.

Rain-out / condensation

Condensation that forms when humidified gas cools; influenced by temperature differences, ambient temperature, gas flow, and circuit characteristics.

Water trap

A low point in the breathing circuit designed to collect condensate and reduce moisture reaching the patient.

Cross-contamination

Bacterial growth in the breathing circuit; avoid draining condensate back into the humidifier and minimize circuit changes.

Infectious waste

Condensed moisture in the breathing circuit is treated as potentially infectious waste; handle with appropriate precautions.

Nasal cannula

A delivery device for oxygen therapy; bubble humidifiers are commonly used with nasal cannula to improve humidity.

Relief valve

A safety valve that releases excess pressure to protect the device from pressure damage.

Pressure relief port

An outlet that allows excess pressure to escape, protecting the system from over-pressurization.

Bypass airway

An airway in which heated humidification is often needed because the natural humidification by the nose/pharynx is bypassed.