Aerosol and Humidity Therapy

AEROSOL AND HUMIDITY THERAPY WHAT IS MUCOCILIARY CLEARANCE? • Mucociliary clearance has long been known to be a significant innate defence mechanism against inhaled microbes and irritants. • When breathing, inhaled particles such as dust and bacteria inevitably reach the conducting airways. As a respond to this constant threat of inflammation and infection the airways have evolved different innate defense mechanisms. • Mucociliary clearance is known to be of particular importance in this first line of defense. THE CILIA • Cilia are slender, microscopic, hair-like structures or organelles that extend from the surface of nearly all mammalian cells (multiple or single). • The length of a single cilium is 1-10 micrometres and width is less than 1 micrometre. • Cilia are broadly divided into two types. They function separately and sometimes together: • Motile (MOVING) Cilia • Non-Motile (PRIMARY) Cilia MOTILE (MOVING) CILIA • 'Motile' (or moving) cilia are found in the lungs, respiratory tract and middle ear. These cilia have a rhythmic waving or beating motion. They work, for instance, to keep the airways clear of mucus and dirt, allowing us to breathe easily and without irritation. NON-MOTILE (PRIMARY) CILIA • 'Non-motile or 'primary' cilia is recognized as a crucial role in a number of organs. Some act as a sensory antenna for the cell, receiving signals from other cells or fluids nearby. THE MUCUS LAYER • Apart from the numerous ciliated cells, the epithelial lining of the intrapulmonary airways consists mainly of secretory cells. These cells release different antimicrobial molecules, immunomodulatory molecules, and large glycoproteins called mucins that bind considerable amounts of water whereby the deformable gel known as mucus is generated. • In healthy individuals, mucus from the airways contains 97% water and only 3% solids of which mucins constitute around 30% HUMIDITY THERAPY HUMIDITY • Is the quantity of moisture in air or gas that is caused by the addition of water in a gaseous state or vapor. It is also called molecular water or invisible moisture. GOALS OF HUMIDITY THERAPY • To humidify dry therapeutic gases. • To provide 100% body humidity of the inspired gas for patients with ET tubes or tracheostomy tubes. NORMAL AIRWAY HUMIDIFICATION • The nose warms, humidifies, and filters inspired air. • The pharynx, trachea, and bronchial tree also warms, humidify, and filter inspired air. • By the time inspired air reaches the oropharynx, it has been warmed to approximately 34 C and is 80% to 90% saturated with H20. • By the time the inspired air reaches the carina, it has been warmed to body temperature (37 C) and is 100% saturated • When the inspired air is fully saturated (100%) at 37 C, it holds 44 mg H20 per liter of gas and exerts a water vapor pressure of 47 mm Hg PRINCIPLES OF HUMIDIFICATION • Absolute Humidity • Relative Humidity • Potential Humidity • Body Humidity ABSOLUTE HUMIDITY • It is the amount of water in a given volume of gas; its measurement is expressed in Milligrams/Liter. RELATIVE HUMIDITY • Is the ratio between the amount of water in a given volume of gas and the maximum amount it is capable of holding at that temperature. Its measurement is expressed as a percentage and is obtained with a hygrometer POTENTIAL HUMIDITY • The amount of water vapor that a gas can hold at a given temperature. BODY HUMIDITY • The relative humidity at body temperature and is expressed as a percentage. ABSOLUTE HUMIDITY FORMULA •Relative humidity x capacity ABSOLUTE HUMIDITY • A gas at 22 C has a relative humidity of 51%. AT 22 C, air can hold 17.35 mg H20 per liter. Calculate the absolute humidity • Relative humidity x capacity • .51 X 17.35 =8.8 mg/L ABSOLUTE HUMIDITY • A gas at 27C has a relative humidity of 66%. At 27C, air can hold 32.15 mg H20 per liter. Calculate the absolute humidity. • Relative humidity x capacity • .66 x 32.15 = 21.2 mg/L RELATIVE HUMIDITY FORMULA • Relative Humidity = Absolute humidity 100 capacity x • The amount of moisture in a given volume of gas at 33 C is 26 mg H20 per liter of gas. (At 33 C,air can hold 36.75 mg H2O per liter) Calculate the relative humidity • Relative humidity x 100 capacity 26 mg/L = .70 X 100 36.75 mg/L = 70% RELATIVE HUMIDITY • The amount of moisture in a given volume of gas at 37C is 30 mg H20 per liter of gas. At 37C, air can hold 67.31 mg H20/L. Calculate the relative humidity • Relative humidity x 100 capacity 30 mg/L = .44 x 100 67.31 mg/L = 44% HUMIDITY DEFICIT • Is the inspired air that is not fully saturated at body temperature. • This deficit is corrected by the body’s own humidification system. • Humidity deficit may be expressed in milligrams per liter or as a percentage. HUMIDITY DEFICIT FORMULA • 44 mg/L – absolute humidity If expressed as percentage: Humidity deficit mg/L x 100 44 mg/L TAKE NOTE: • 44 mg/L is the capacity of water at body temperature HUMIDITY DEFICIT • A patient on a T-tube flow-by is inspiring air from a nebulizer that contains 18 mg H20 per liter of air. What is the patient humidity deficit? SOLUTION: • 44 mg/L-absolute humidity • 44 mg/L - 18 mg/L = 26 mg/L • 26 mg/L = .59 X 100 44 mg/L = 59% HUMIDITY DEFICIT • A patient on a T-Tube flow-by is inspiring air from a nebulizer that contains 22 mg H20 per liter of air. What is the patient humidity deficit? SOLUTION: • 44 mg/L-absolute humidity • 44 mg/L - 22 mg/L = 22 mg/L • 22 mg/L = .50 X 100 44 mg/L = 50% INHALATION OF DRY GASES COULD RESULT IN THE FOLLOWING: • Impaired ciliary ability • Slowed mucus movement • Inflammation and necrosis of pulmonary epithelium • Retention of thick secretions • Bacterial infiltration of mucosa, atelectasis and pneumonia WHEN DO WE APPLY HUMIDIFICATION? • Impaired ability to cough and move secretions • Presence of very thick, abundant amount of secretion • Delivering medication TAKE NOTE: • If adequate humidity is not provided, the patient’s airway can dry out, which can lead to thickening of secretions and result in increased airway resistance. • Gas being delivered to a patient with an ET tube or tracheostomy tube that contain less than 44 mg H20 per liter of gas or a water vapor pressure of less than 47 mm Hg tends to dry secretions, making them thicker and more difficult to mobilize. EVALUATION OF THE EFFECTIVENESS OF THE THERAPY • Check the patient’s secretions • Listen to the breath sounds • Look for clearing or improvement in chest xray MODE OF DELIVERY OF HUMIDITY THERAPY: • Humidifiers • Nebulizers HUMIDIFIERS • To deliver a gas with a maximum amount of water vapor content • Must be heated or unheated • Can deliver 80%-100% relative humidity EFFICIENCY OF HUMIDIFIERS The efficiency of humidifiers depend on three important factors:  Duration of contact between the gas and water. (Longer duration results in increased humidity) for example: A. The higher the flow rate used, the less time of contact between the gas and water and therefore the lower humidity output. B. The lower the water level in the jar, the less time of contact between the gas and water and therefore the lower humidity output.  Surface area of gas and water contact. (Greater surface area results in increased humidity)  Temperature of the gas and water. (Higher temperature results in increased humidity) TYPES OF HUMIDIFIERS • Passover or blowby • Bubble humidifier • Wick humidifier • Heated wire • Heat moisture exchange • Cascade humidifier PASS-OVER OR BLOWBY • It is a humidifying device that directs a dry gas source over a water surface area and then flows to the patient • Least effective in humidifying an artificial airway • Provides body humidity approximately 25% BUBBLE HUMIDIFIER • a conduction system which allows the gas to introduced into the water below its surface. • commonly used in most respiratory care • Provides a body humidity of 35% TO WICK HUMIDIFIER • most common humidifier • The wick is the filter that absorbs water from the reservoir and provides a large surface area for it to evaporate. • Can deliver 100% body humidity • Appropriate for use with ventilators,bubble CPAP,etc. HEATED WIRE • Complements the humidification therapy and is designed with patient safety and reliability in mind. • heat the air in the circuits and maintain the temperature HEAT MOISTURE EXCHANGE (HME) • Also called hydroscopic condenser humidifier or artificial nose. • Ideal use is for patient transport and short term ventilation • Must be removed during aerosol therapy • Should be located in the ventilator circuit between the wye and the patient • May be used for temporary humidification during transport • In ideal condition: it produces 70%- 90% body humidity. CASCADE HUMIDIFIER • used when the nasopharyngeal route is bypassed (ETT or tracheostomy tube) • Can deliver 100% humidity • Only wide bore tubing should be used with this device AEROSOL THERAPY WHAT IS AEROSOL? • Aerosol is defined as a suspension of water in particulate form (or mist) in gas. Nebulizers produce aerosolized gas. Nebulizers are often referred to as aerosol generators. GOALS OF AEROSOL THERAPY • To administer medications (via handheld nebulizer or ultrasonic nebulizer) • Treatment of upper airway edema • To hydrate the airway of a tracheostomy patient • To induce a cough for sputum collection (sputum induction) HAZARDS OF AEROSOL THERAPY • Bronchospasm (administration of a bronchodilator may decrease the potential of this hazard) • Overhydration • Overheating of inspired gas • Tubing condensation draining into the airway • Delivery of contaminated aerosol to the patient CHARACTERISTICS OF AEROSOL PARTICLES • The ideal particle size for therapeutic use in respiratory care is 1.0 to 5.0 μm FACTORS THAT AFFECT THE PENETRATION AND DESPOSITION OF AEROSOL PARTICLES • Gravitational sedimentation • Brownian movement • Inertial impaction • Hygroscopic properties • Ventilatory pattern GRAVITATIONAL SEDIMENTATION • The larger a particle is, the more effect gravity has on it and the sooner it will deposit BROWNIAN MOVEMENT • Affects particles of 0.1 μm or smaller in size, which will deposit too soon. (Possible in the aerosol tubings) INERTIAL IMPACTION • Larger particles have greater inertia, which keeps them moving in a straight line. Because they cannot make directional changes in the airway, they deposit sooner. HYGROSCOPIC PROPERTIES • Aerosol particles are hygroscopic (retain moisture). As they travel down the airway, they may increase in size as they retain moisture, which may alter the time at which they deposit. VENTILATORY PATTERN • The most important variable that can be controlled. • To obtain optimal particle penetration, the patient should be instructed to take slow, moderately deep breaths with a 2 to 3 second breath hold at end inspiration FACTORS AFFECTING THE AREA OF DEPOSITION OF AEROSOL PARTICLES • Stability • Penetration and Deposition • Composition of aerosol particles • Heating and humidification STABILITY • The tendency of particles to remain in suspension. 3 factors are:  Size  Concentration  Humidity PENETRATION AND DEPOSITION • Penetration refers to the depth within the respiratory tract that an aerosol reaches. • Deposition is the aerosol particles within the respiratory tract COMPOSITION OF AEROSOL PARTICLES • Hypertonic particles absorb water, becomes larger. • Hypotonic particles evaporate and get smaller, goes deeper into the bronchial tree. • Isotonic stay stable in size until deposited. HEATING AND HUMIDIFICATION • Particle size increases when warm gas cools DIFFERENT TYPES OF NEBULIZER • PNEUMATIC • ELECTRIC AEROSOL PARTICLE SIZES • The ideal particle size for therapeutic use is 1 to 5 μm • In Pneumatic nebulizers, 55% of particles fall in therapeutic range. • In Ultrasonic nebulizers, 97% of particles fall in the therapeutic range of 1 to 5 μm TYPES OF PNEUMATIC NEBULIZER • Jet Nebulizer • Large volume nebulizer • Small volume nebulizer/Hand held • Metered dose inhaler JET NEBULIZER JET NEBULIZER • Most common method of producing an aerosol particle for use in respiratory therapy. • Jet nebulizer utilizes high velocity gas flow to generate aerosol particles from the water reservoir LARGE VOLUME NEBULIZER LARGE VOLUME NEBULIZER • delivers bland aerosol to the upper airway • decrease the chances of edema or humidity deficit. • Incorporate with an air entrainment device to administer 21 to 100 Fio2% • Can hook to a base heated humidifier for patients with thick secretions. • uses large bore corrugated tubing to connect to the nebulizer. SMALL VOLUME NEBULIZER OR HANDHELD SMALL VOLUME NEBULIZER OR HANDHELD • Used to nebulize small doses of medication • Powered by pressurized gas source. METERED DOSE INHALER (MDI) METERED DOSE INHALER (MDI) • Device use to deliver medication in aerosol form by squeezing the vial • Only 10% of dose reaches the lower respiratory tract • The MDI should be activated just after you start inhaling TYPES OF ELECTRIC NEBULIZER • Small particles aerosol generator • Ultrasonic Nebulizer SMALL PARTICLES AEROSOL GENERATOR(SPAG) SMALL PARTICLES AEROSOL GENERATOR(SPAG) • designed to deliver Ribavirin(Virazole) for treating respiratory synctial virus • Not to be used with any other substance • Produces a uniform particle size 1.3 um ULTRASONIC NEBULIZER (USN) ULTRASONIC NEBULIZER (USN) • “piezoelectric principle” • A sound wave is applied to a quartz crystal or a ceramic disc causing it to vibrate. • Particles size falls 1-5 microns • Advantages • High aerosol output • Smaller stabilized particle size • Deeper penetration into the tracheobronchial tree • Amplitude controls the output • Frequency controls the particle size