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66 Cards in this Set
- Front
- Back
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Absolute Humidity at 37degrees C
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44mg/L
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Water Vapor Pressure at 37degrees C
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47mmHg
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Body Temperature Pressure Saturated(BTPS)
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The amount of water a gas can hold at body temperature and atmospheric pressure
44mg/L-absolute humidity 47mmHg-water vapor pressure |
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Humidity Deficit
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Difference between actual content and BTPS humidity(44mg/L)
-44mg/L is desired at the carina |
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How does the nose control the heat and moisture exchange
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Inspiration- gas travels through nose and contacts turbinates which increase surface area. 50% of heat and humidification
Exhalation- gas is cooled, cooler gas condenses and gives water back to the mucosa |
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How does the mouth control the heat and moisture exchange
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Not as efficient as the nose
3degrees C less heating 20% less humidification less surface area |
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Isothermic saturation boundary
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Point at which body temperature pressure standard (BTPS) is reached
Normally reached at the carina |
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What causes the isothermic saturation boundary to shift deeper into the lung?
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Mouth breathing
Bypassing upper airway(Intubation, tracheostomy) Inspired air is abnormally cool or dry Increased minute ventilation(exercising) |
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How does humidity deficit occur?
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If the body's own compensation mechanisms cannot keep up
Supplemental heating and humidification is needed |
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What is the primary goal of Heating and Humidification?
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To maintain normal conditions int he lower airway
-Maintain normal mucocilliary transport -Treat abnormal conditions (Dry inhaled gas, upper airway bypass, managing hypothermia, bronchospasm due to cold air) |
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What is a Humidifier and what principles govern its function
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Any device that adds molecular water to a gas
-Temperature -Surface Area -Contact Time |
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What are the three types of Humidifiers
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Bubble
Passover Heat and Moisture Exchangers |
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Describe a Bubble Humidifier
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Diffuser submerged under water breaks gas into small bubbles
-not real effective -for LOW flow systems -2psi pop off valve -Not used/ineffective less than 4L/min -used with sterile water |
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How does flow rate effect bubble humidifiers
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Higher flows spend less time in water meaning less contact time and less humidity
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What are the two types of Passover Humidifiers and what traits do they share
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Wick Humidifier
Membrane Humidifier -Used for higher flows -Provide little or no resistance to flow -No aerosols generated(no mist) |
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Describe a Wick Humidifier
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Very effective
Water bag and float keep water line constant Wick is suspended in water and up the lateral walls Heater warms the wick and adds humidity to the air that runs out the capillary and through the outlet |
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Describe a Membrane Humidifier
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Heating plate is beneath a water supply
A hydrophobic membrane covers the water to make contact with the gas The gas comes through an inlet, over the membrane collecting humidity and out to the pt |
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What are the characteristics of Heat and Moisture Exchangers
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"Artificial Nose"-Uses body's own heat and humidity
Used with ventilated pt's -Uses pt own gas to pull water and heat from it for the next inspiration -Used for 24-48hrs then switched over to passover |
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What are the three types of Heat and Moisture Exchangers?
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Simple Condenser
Hydroscopic Hydrophobic |
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What is a Simple Condenser HME
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Contains metal condenser
On inspiration condenser gives up heat to gas On exhalation expired water vapor collects on condenser Only about 50% efficient |
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What is a Hygroscopic HME
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Condenser element of lower thermal conductivity
Likes water Is about 70% effective |
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What is a Hydrophobic HME
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Water repellent material
Large surface area Low thermal conductivity Is about 70% effective Contains *Bacterial Filter |
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Characteristics of Heating Systems
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Heating a humidifier is the #1 way to increase the function of the humidifier
Heated wire is usually used in conjunction w/ another heater- it helps to prevent condensation or cooling of the gas in the tubing going to the pt |
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Five Types of Heaters
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Hot plate
Wraparound Yolk or Collar Immersion Heated wire |
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What is a Servo Controller
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Measures temperature at the pt artificial airway
-has alarms |
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Reservoirs and Feed Systems with Heated Humidifiers
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Reservoirs added to reduce number of times the system needs to be opened
Auto feed systems eliminate opening the system Helps prevent nosocomial infections |
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What do we set Humidification at?
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Literature says 30mg/L and 33degrees C
Others suggest 44mg/L and 37degrees C Anything above or below will harm pt airways |
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How often should we change circuits
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Only if visibly soiled or malfunctioning
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What in the tubing shows us we have 100% relative humidity?
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Fog formation in tubing
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Definition of Aerosol
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Particulate matter suspended in a gas
May be a liquid or a solid Particle sizes ranges from submicroscopic to macroscopic |
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Definition of Bland Aerosol
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Aerosol with no active medication in the aerosol
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What are the three properties of aerosol and define them
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Stability- ability of particles to stay in suspension during travel
Penetration- how deep in the lungs will the particles go Deposition- how well can you get it to deposit where you want it to be |
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Factors that affect stability of an aerosol
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Particle size- smaller=more stable, larger= less stable/more likely to rain out
Particle concentration- more particles=more likely they'll combine, get larger, and rain out Humidity- higher the RH the greater the stability/more humid=more particle can be held in suspension |
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Factors that affect penetration of an aerosol
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Gravity- decreases penetration, causes particles to rain out quicker, however has little effect on particles 1-5 microns
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Factors that affect deposition of a gas
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Gravity- causes particles to rain out quicker (>5 microns)
Kinetic Energy- More kinetic energy causes more particle impactions creating larger particles and rain out Inertial Impaction- increases at any branch in airway. smaller airway diameter increases wall impactions as well (must slow pt breathing pattern for deep penetration) |
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Physical nature of particles and what influences their physical properties
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Particles can grow or shrink in suspension based on their composition
Some are hygroscopic in nature causing them to grow in size -influenced by liquid itself(medication), tonicity of solution, humidity, and temperature |
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Describe the types of tonicity of aerosol particles
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Hypertonic- Greater concentration of salt so it absorbs water and grows
Isotonic- Same concentration (Normal saline-0.9% salt concentration) Hypotonic- Low concentration of salt so it takes in salt and shrinks |
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What type of solutions are used to collect sputum
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Hypertonic- very salty makes it irritating to the airways and produces cough
Sterile water- wants to pick up sodium from body |
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What is the most important variable that can be controlled to maximize aerosol penetration and deposition
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pt ventilatory pattern
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What is the ideal ventilatory pattern for optimal penetration and deposition?
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Liquid aerosol- flow rate of 30L/min, take breath in over 3-4 seconds
Dry aerosol- flow rate of 60L/min After Inhalation- hold breath 4-10 sec (particles lose velocity/maximizes deposition) Exhalation- relaxed an normal Encourage cough after therapy |
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Three ways to remove aerosol from lungs
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Primary mechanism- mucocilliary esclator (moves 100ml per day, most is swallowed)
Normal coughing Phagocytosis- Type III alveolar cells, engulfs liquid, discards through circulatory system |
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Two types of Aerosol Generators
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Atomizer
Nebulizer |
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Atomizer Aerosol Generator
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Jet and capillary
-Tube that narrows into a jet meets a capillary. High velocity from the jet lowers the pressure of the capillary and draws liquid over the jet. The jet breaks the liquid into particles -Generally large particles produced, used for pt upper airway (croupe) |
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Nebulizer Aerosol Generator
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Works like a atomizer with a jet and capillary but contains a baffle(ball, or wall/siding) which breaks down particles even smaller than the jet was able to do.
-Generally small particles |
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Three types of Nebulizer Aerosol Generators
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Mainstream
Side Stream Ultrasonic (USN) |
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Mainstream Nebulizer Aerosol Generator
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Aerosol is created in the mainstream of the gas flow
-Not as small of particles |
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Side Stream Nebulizer Aerosol Generator
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Aerosol is picked up by the main gas flow from a side stream
-creates smaller particles using siding of container as a baffle |
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What is a Ultrasonic Nebulizer (USN)
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High frequency sound device to produce aerosol
Function by transforming standard household current into ultrasonic sound waves FCC governs frequency range 1-2 megacycles/per sec (1-2 million cycles a sec) |
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Ultrasonic sound waves are applied to what
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crystal or ceramic disk whch vibrate at the same rate as the sound waves
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What is piezoelectric quality
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ability of a ceramic disk to vibrate at the same rate of the ultrasonic sound waves
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Energy is transferred from crystal or ceramic disks to what
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a couplant chamber fluid
or directly to fluid to be nebulized |
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What two aspects of ultrasonic waves will effect the aerosol
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Frequency- effects particle size (set at factory ie. 1-2 megacycles/sec)
Amplitude- determines output(volume of aerosol)- can be controlled. Higher amplitude creates more dense aerosol. Less amplitude creates a less dense aerosol |
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What are Ultrasonic Nebulizers used for?
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Bland aerosol for sputum induction(make person cough)
New smaller units for medical delivery |
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Compare USN to Jet Nebulizers for Aerosol Output and Particle Sizes
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Aerosol Output: Jet- 1-1.5ml/min vs USN- up to 6ml/min
Particle Sizes: Jet- 55% of aerosol in 1-5 micron range vs USN- 97% of aerosol in 1-5micron range (wonderful particle size) |
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Parts of the USN from wall to outlet
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1.Radiofrequency generator
2. Shielded Cable 3.Piezoelectric/Crystal Transducer 4. Couplant Reservoir 5. Solution Chamber 6 Chamber Inlet 7. Chamber Outlet |
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Continuous use of Ultrasonic Nebulizers is only used on who
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Adults
It could drown infants with prolonged use |
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Bland aerosol delivers what solutions? with what masks? and is for what use?
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1. sterile water, hypotonic, isotonic, hypertonic saline (no active medication)
2. mask, trach collar, face tent, t-piece 3. humidification, induction of sputum |
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Large volume jet nebulizer information
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most common device used
pneumatically powered uses air entrainment for FiO2 Can be heated cold= 26-35mg/L heated= 33-55mg/L |
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Disposible Nebulizers
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Prefilled with solution
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Issue with Heated Aerosols
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Can have infection issues
Organisms like to live in moist and warm enviornments |
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Bland Aerosol: Oxyhood
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Used for infants
Fed by either heated aerosol, cool aerosol, heated humidication -biggest negative is the sound being extremely loud |
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Sputum Induction: Purpose
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Diagnostic tool
-useful to culture organism -useful to test sensitivity of organism to antibiotics -very important to know what organism is infecting the pt |
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Sputum Induction: Short term appplication of hypertonic saline (3-10%)
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Most effective when used with USN
-gives most dense aerosol -helps pt to cough |
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Bland Aerosol Therapy: Problem Solving and Troubleshooting (Cross contamination and infection)
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Circuits should be changed every 24-48hrs
Water should be changed regularly USNs should be disinfected between use |
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Bland Aerosol Therapy: Problem Solving and Troubleshooting (Overyhydration)
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Can happen with continuous administration
-more problem with USN -should not recieve more than 200ml per day via aerosol Can swell dried secretions resulting in blocked airways |
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Bland Aerosol Therapy: Problem Solving and Troubleshooting (Bronchospasms)
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Anytime you give aerosol to someone it is possible to cause bronchospasms
-heating sometimes helps this |
