Humidifier PDF

○ Porous water-absorbent HUMIDIFIER materials (by means of capillary Humidifier action). A device used to add moisture to the ○ The s...

○ Porous water-absorbent HUMIDIFIER materials (by means of capillary Humidifier action). A device used to add moisture to the ○ The surfaces of the wick oxygen being delivered to a patient. increase the area of contact This process occurs by evaporating between the water and gas. water from a surface to a gas not 100% saturated with water vapor. Time of Contact It is commonly used in higher-flow The longer a gas remains in contact with oxygen therapy to prevent dryness in water, the greater the opportunity for the nose, throat, and lungs. evaporation to occur. ○ Bubble humidifiers’ contact time Physical Principles depends on the depth of the water column Variables affecting humidifier function: Deeper = greater time ➔ Temperature of contact ➔ Surface Area ○ Pass-over and wick-type ➔ Time of Contact humidifiers ➔ Thermal Mass Flow rate of gas through the humidifier is Temperature inversely related to Most important factor contact time Higher temperature = more water vapor = increased capacity Thermal Mass The greater the amount of water in a Surface Area humidifier, the greater the thermal mass. The larger the contact area between ○ Larger-reservoir humidifiers can water and gas, the greater the possibility provide more consistent heat of evaporation. and humidification with a ○ Pass-over humidifiers increase broader range of gas flow. the water-to-gas surface area, allowing more water to Indications evaporate. ○ Bubble diffusion, aerosol, and Primary wick methods are more ➔ Humidify dry medical gases space-efficient ways to increase ➔ Overcoming humidity deficit created contact area. when the upper airway is bypassed Secondary Bubble diffusion ➔ Bronchospasm ○ Directing gas through water ➔ Thick or Bloody Secretions creates small bubbles, ➔ Low Expired Tidal Volume increasing evaporation. ➔ Hypothermia ○ ↓bubble, ↑ratio of water ➔ High Minute Ventilation Aerosol method ➔ Noninvasive Ventilation ○ Spraying water particles into the ➔ Lung-Protective Ventilation gas enhances evaporation. ➔ In-line Aerosol Drug Treatments ○ ↑aerosol density = ↑ surface area Wick method  Hazards & Complications Room-temperature fluids for noninvasive ➔ Potential electrical shock ventilation (nasal CPAP ➔ Potential for burns to caregivers from or bilevel ventilation) hot metal ○ Wick type ➔ Underhydration and mucous impaction Uses absorbent materials to increase Types of Humidifiers the contact between dry ➔ Active Humidifiers air and heated water ➔ Passive Humidifiers The wick is placed in a ➔ Heat and Moisture Exchangers water reservoir and ➔ Heated Humidifiers heated, causing water to rise through capillary action Active Humidifiers As dry air passes over Humidifiers that actively adds heat, the wet wick, it absorbs water, or both to the device-patient heat and moisture, interface. Includes bubble humidifiers, leaving the chamber pass-over humidifiers, nebulizers of humidified bland aerosol, and vaporizer. ○ Membrane type Separates heated water Bubble Humidifier from the gas stream by Breaks a gas stream into smaller means of a hydrophobic bubbles underwater, which increases membrane the surface area allowing for more efficient evaporation Nebulizer of Bland Aerosol Uses a foam or mesh diffuser Serves as an active humidifier by Unheated bubble humidifiers are used directly adding moisture to the airways. with oxygen delivery systems to ensure Useful for those with dry respiratory that the delivered gas has the conditions or those who needs to thin appropriate humidity level mucus secretions. Uses a simple pressure-relief valve or a pop-off ○ Warns flow-path obstruction and Vaporizers prevents bursting of the Simple vaporizers heat water to the humidifier bottle point of expansion as a gas. Simple room vaporizers have been used in ambulatory settings for years as room Pass-Over Humidifier humidifiers. Direct gas over a surface containing water Simple reservoir, wick, and membrane Heat and Moisture Exchangers type. Passive humidifiers that recapture ○ Simple reservoir type exhaled heat and moisture. Directs gas over the Do not add heat or water actively. surface of a volume of Primarily used for patients receiving water ventilatory support. Heated fluids for Also called artificial nose. invasive mechanical ventilation Simple condenser humidifiers  ○ Condenser element with high Heat improves the water output of thermal conductivity. humidifiers. ○ Recapture up to 50% of exhaled Heated humidifiers are used to increase moisture. the heat and water content of inspired Hygroscopic condenser humidifiers gas ○ Condensing element with low Humidifier heating systems generally thermal conductivity (e.g., have a controller paper, wool, or foam). Humidifier heating systems have a ○ Infused with hygroscopic salt. controller that regulates the element’s ○ Higher heat and moisture electrical power. retention. Hydrophobic condenser humidifiers Five types of heating elements are common: ○ Water-repellent element with ➔ Hotplate element large surface area and low ➔ wraparound type thermal conductivity. ➔ yoke or collar ○ High efficiency (comparable to ➔ immersion-type heater hygroscopic condenser HMEs). ➔ heated wire ➔ thin-film high surface boiler Design and Performance Standards are set by the International Problem-Solving and Organization for Standardization (ISO). Troubleshooting Ideal HME unit: ○ Operates at 70% efficiency or ➔ Condensation better (providing at least 30 ➔ Cross-contamination mg/l. water vapor) ➔ Proper conditioning of the inspired gas ○ Uses standard connections. ○ Has low compliance. Condensation ○ Adds minimal weight, dead When the gas cools while moving space, and flow resistance. through the ventilator tubing, reducing its ability to hold water vapor. Factors Affecting HME Performance: Leads to: ➔ Breathing volumes and rates. ○ Disrupted gas flow ➔ Inspiratory flows and FiO2 levels. ○ Equipment failure ➔ Flow resistance. ○ Infection if aspirated ➔ Underlying lung disease. Solutions: ○ Water Traps Active Heat and Moisture Exchange ○ Keep the gas warm by Active HME units add humidity, heat, or insulating the tubing or using both to inspired gas by chemical or heated-wire circuits. electrical means. For neonates: Active HME units add weight and ○ Temperature probe should be complexity at the patient airway. placed outside the heated The Humid-Heat consists of a supply environment unit with a microprocessor, water pump, and humidification device. Cross-contamination Due to bacteria from aerosol and Heated Humidifiers condensation in ventilator circuits.  Technological advances have reduced this risk ○ Wick-type and membrane-type humidifiers prevent bacteria-carrying aerosols ○ Heated-wire circuits reduce condensate production and pooling ○ High reservoir temperatures in humidifiers kill bacteria Recommendation ○ Weekly circuit changes or only when visibly soiled Proper conditioning of the inspired gas Measuring Temperature & Humidity ○ Portable battery-operated digital hygrometers Ensure proper humidification ○ Adjust the temperature differential until a few drops of condensation form near the patient’s connection ("wye").