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86 Cards in this Set
- Front
- Back
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List Common Medical Gases
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Oxygen (O2)
Air Carbon Dioxide (CO2) Helium (He) Nitrous Oxide (N2O) Nitric Oxide (NO) |
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Characteristics of Oxygen
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Colorless, odorless, tasteless, transparent
Non-flammable but accelerates combustion greatly |
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Oxygen Production (Methods)
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Chemical Methods, Fractional Distillation, Physical Separation, Membrane Method
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Oxygen Production (Chemical Methods)
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Used for production of small quantities
-Electrolysis of water is most common |
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Oxygen Production (Fractional Distillation)
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Produces mass quantities, Least expensive method, used for most hospitals
-Air filtered, Gas dried, Gas compressed, Gas decompresses, Temp is increased to boiling point and is released in pure form |
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Oxygen Production (Physical Separation)
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Used in home oxygen therapy
Sieve method- air passed through sieve beds to remove everything but O2. Produces at least 90% O2 at 5-10L/min Membrane Method- Air passed through a membrane that allows only O2 and water vapor to pass. Produces about 40% O2 |
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Characteristics of Air
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Odorless, colorless, less dense than O2
Naturally occurring: Oxygen= 20.9% Nitrogen= 78.1% <1%= trace gases |
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Medical Air Production (Methods and Description of Methods)
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Large compressors- Used to provide flow rates at 50 psi. Gas is pulled into a reservoir. When leaving reservoir it is dried and passes through the pressure reducing valve
Small Compressor- For home use to drive small volume nebulizers (med admin) Do NOT have reservoir, produce flows of about 6 L/min |
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Carbon Dioxide Characteristics
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Colorless, Ordorless, Denser than O2 and Air,
Does NOT support combustion |
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Carbon Dioxide Production (Method + Description)
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Heating Limestone and water
Gas recovered from the process is liquefied by compression and cooling |
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Carbon Dioxide (Uses)
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Used in 5-10% Mixtures.
-Treats hiccoughs -Treats atelectasis- use CO2 to open closed areas of the lungs by increases the pt's drive to breathe Now most commonly used to calibrate blood gas anaylizers |
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Helium Characteristics
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Low density, Odorless, Colorless,
Non-flammable Cannot support life |
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Helium (Uses)
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Mixed with AT LEAST 20% oxygen. Mixture of 40-80% may be used.
-Used in obstructed or turbulented airways. Lighter air moves easily around obstructions. Decreases pt work of breathing and is given through a mask or vent. Read 1.8x Flow meter b/c flow meter is calibrated to oxygen |
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Nitrous Oxide Characteristics
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Colorless, Slightly sweet odor, Slightly sweet taste,
Supports combustion 100% Cannot support life -Must always be mixed with 20% oxygen |
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Nitrous Oxide Production (Method)
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Thermal decompression of ammonium nitrate
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Helium Production (Method)
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Fractional Distillation
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Nitrous Oxide (Uses)
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Used as an anesthetic, usually in combination
-Depresses central nervous system -Known as laughing gas |
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Nitric Oxide Characteristics
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Colorless, Toxic
Non-flammable Supports combustion |
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Nitric Oxide (Uses)
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FDA approved for <35week infants with hypoxic respiratory failure on mech vent. (relaxes the smooth muscles of the pulmonary vessels to increase blood flow and decrease cardiac work)
-High concentrations of NO can cause methemeglobemia(decrease in bloods carrying capacity of oxygen) |
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Nitric Oxide Production (Method)
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Oxidation of ammonia
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Storage of Medical Gases (Types)
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-Typically stored in high pressure cylinders
-Large bulk systems |
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Cylinder Markings (Front)
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Line 1: DOT- Department of Transportation, Cylinder Type (ex. 3AA), Service Pressure (max working pressure)
Line 2: Cylinder Serial Number Line 3: Ownership Mark Line 4: Manufacturers Mark |
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Cylinder Markings (Rear)
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Line 1: Original hydrostatic test date, Elastic Expansion (ex. E.E 17.5)
Line 2: Material used to construct cylinder Line 3: Construction process (ex. SPUN), Collumn of dates under EE *=10yr satisfactory, +=cylinder can be filled 10% above service pressure |
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Cylinder Color Codes
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Bureau of Standards of the US Department of Commerse
-Mandatory only on E cylinders and smaller O2-Green Medical Air-Yellow CO2-Gray Nitrous Oxide- Navy Helium- Brown |
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Cylinder Sizes and Cylinder Factors
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AA, BB, DD, A, B, D-0.16, E-0.28, G-2.41, H-3.14
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Large Cylinders
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-Sizing- G, H/K, M, N
-Hexagonal nut fitting -American Standard Safety System (ASSS) -Direct or Indirect acting valves -Frangible Disk(crumble) or Spring Loaded Valve(burst) as safety relief (5%< cylinder bursting pressure) |
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Small Cylinders
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-Sizing- E through AA
-Pin Index Safety Systems (PISS) -Fusible Plug safety relief valve(Melts at 150-170degree F) |
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Measuring Cylinder Contents in Compressed Gas Cylinders
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Amount of gas in cylinder is proportional to pressure in cylinder
ex. if cylinder contains 2200psi when full, and currently contains 550psi. It is 25% full 550/2200=0.25 |
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Measuring Cylinder Contents in Liquid Gas Cylinders
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Pressure remains the same when liquid is in cylinder
When liquid depletes the pressure will drop as the left over gas depletes |
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Calculating Cylinder Duration
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Duration of Flow= Cylinder Contents(in L)/Flow given to pt
Contents= Pressure x Cylinder Factor |
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Bulk Gas/Oxygen Systems
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Initially expensive, cheap in long run
Eliminates hazards of storing large numbers of large cylinders Operate at LOW pressures- 50-70 psi |
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Gas Supply System (Types)
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Alternating Supply Cylinder Manifold
Supply System with Reserve Bulk Liquid System |
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Gas Supply System (Alternating Supply Cylinder Manifold)
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-Made up of H/K cylinders
-Automatically switches banks when pressure decreases to a preset level -Empty bank then is changed and becomes reserve bank -Best for small facilities or OR's with nitrous oxide |
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Gas Supply System (Supply System with Reserve)
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-Alternating supply with a reserve
-Could be cylinders or liquid with cylinder reserves |
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Gas System Supply (Bulk Liquid System)
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-Small amount of liquid provide a lot of gas (minimizes space needed and very economical)
-Large tanks at low pressure- 250psi -Large thermo containers with a vacuum separating inner and outer shell to keep liquid gas cold and vaporizers to heat liquid to gas -Pressure reducing valve to take it to 50 psi working pressure |
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Bulk Liquid System Safety
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Reserve must match average daily use amount (24-48hr worth of back up)
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Central Piping Systems
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Main comes from bulk oxygen system
Main goes to risers to feed floors Zone valves are between risers and floor/wing. Allows us to shut down certain areas of the hosp w/ out shutting down the whole system |
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American Standard Safety System (ASS)
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High Pressure Fitting (>200psi)
Used for Large cylinders (above E) Typically hex nut with threads Some gases share threads so its not perferred Varies thread diameter, threads per inch, and right or left handed threading |
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Pin Index Safety Systems (PISS)
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High Pressure fitting (>200psi)
Used for Small cylinders (E and below) Yoke containing pins fits over valve system Two pins per gas (O2=2,5 Air=1,5) Pins overlap so only 10 combinations |
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Diameter Index Safety System (DISS)
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Lower Pressure fitting (<200psi)
Most commonly used for: -Regulator outlets, Station outlets, Inlets for RT equipment (blenders, flowmeters, vents) 12 connections, can be used as a Quick Connect |
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Quick Connect Safety System
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Typically used at station outlets
Allows for quicker connection Specific by gas for preventable misuse May require more maintenance |
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Pressure Reducing Valves
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Takes pressure from cylinder pressure to working pressure (50psi)
-Can be done in one stage or multiple stages -Can be preset or adjustable |
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Multistage Pressure Reducing Valves
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Reduces pressure to working pressure in more than one step
-More precision using gradual pressure reduction -Produce smoother gas flow |
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Regulators (Single Staged)
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Pressure reducing valve with a flow meter
Reduces pressure to working pressure in one step. Preset or adjustable. Adjustable can be adjusted to a pressure between 0 and 100 psi |
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Flowmeters (Flow Restrictor)
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Operate at 50 psi
Vary the size of orifice the gas flows through to vary flow |
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Flowmeters (Bourdon Gauge)
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Operate at 50 psi
Vary pressure through a fixed orifice to vary flow delivered Back pressure compensated (kink in tubing will not effect flow) |
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Flowmeters (Thorpe Tube)
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Utilizes needle valve and float system to measure the flow
Can be back pressure compensated or back pressure uncompensated Most accurate but most expensive Most common in RC Must be used in upright position |
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Definition of Hypoxia
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Inadequate quantities of oxygen at the Tissue level
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What are the four types of Hypoxia
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Anemic Hypoxia
Stagnant Hypoxia Histotoxic Hypoxia Hypoxemic Hypoxia |
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Anemic Hypoxia
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Decreased carrying capacity of blood for oxygen
May be due to: anemia or hemmorrhage, carbon monoxide poisoning, methemeglobemia, dissociation curve of hemeglobin |
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Stagnant Hypoxia
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Decreased cardiac output, resulting in increased transit time for RBC's
Due to: shock, cardiovascular instability, and regional vasoconstriction |
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Histotoxic Hypoxia
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Inability of tissues to use available oxygen
Due to: Cyanide poisoning, rarely accompanied by hypoxemia |
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Hypoxemic Hypoxia
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Reduction in ability of O2 to cross the alveolar capillary membrane
Due to: Low inspired FiO2, ventilation perfusion mismatching, Increased true shunt(perfusion w/ out ventilation, diffusion defects |
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Define Hypoxemia
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Inadequate quantities of oxygen in the blood
-Normal arterial blood O2 level: 80-100mmHg -Mild: 70-79mmHg -Moderate: 60-69mmHg -Severe: <60mmHg |
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Causes of Hypoxemia
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True shunting
Venilation/Perfusion mismatching Hypoventilation Impaired diffusion Decreased ambient oxygen tension |
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Responsive vs Refactory Hypoxemia
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Responsive- Demonstrates a significant response to an increase in the FiO2 (>10mmHg rise in PaO2) Result of ventilation/perfusion mismatching
Refactory- Demonstrates a small, insignificant increase in PaO2(<10mmHg increase in PaO2) Result of true shunting |
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Clinical Manifestations of Hypoxemia
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Usually first- Rapid respiratory rate and/or large tidal volume
Dyspnea, Tachycardia and Hypertension, Peripheral vasoconstriction, Disorientation, Cyanosis, Polycythemia (hemeglobin 16-20) |
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Indications for Oxygen Therapy
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Documented Hypoxemia (Adults, Children, Infants: PaO2 <60mmHg or SaO2 <90%)
(Neonates <28 days old: PaO2 <50mmHg or SaO2<88% or Capillary PO2 <40mmHg |
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Goals of Oxygen Therapy
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Maintain adequate tissue oxygenation
Minimize cardiopulmonary work |
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Four Hazards of Oxygen Therapy
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Retinopathy of prematurity (ROP)
Oxygen-Induced Hypoventilation Absorption Atelectasis Oxygen Toxicity |
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Retinopathy of Prematurity
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Occurs in infants <34 weeks
Incomplete vascularization of the retina or detached retina Factors: O2 sat >96%, keeping O2 sat <96% can decrease risk |
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Oxygen-Induced Hypoventilation
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Increased oxygen levels decreases or elminates hypoxic drive
If we give too much oxygen then they have no drive to breathe (O2 sat 90 or above is good) Oxygen should NEVER be witheld b/c of fear of ventilatory depression |
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Absorption Atelectasis
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Areas of the lungs collapse
Nitrogen maintains aveolar stability and FiO2 >50% washes it out which may cause them to collapse Positive pressure is given to the lungs to keep aveoli open recruiting other aveoli and allowing us to give 100% O2 as needed |
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Oxygen Toxicity
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Affects lungs and CNS
Two factors: FiO2 concentration and exposure time |
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Oxygen Toxicity Viscous Cycle
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O2 toxicity caused increased shunting which causes low PaO2(arterial O2) so we have to give increased FiO2 which causes oxygen toxicity...
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Avoiding Oxygen Toxiity
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Limit 100% oxygen administration to <24 hrs
Decrease to 70% within 48 hrs Decrease to 50% or less within 5 days |
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Three Categories of Oxygen Delivery Systems
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High Flow system
Low Flow system Reservoir system |
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High Flow Systems
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Entire inspired volume is produced by the system
Flow provided consistently exceeds the pt's peak inspiratory flow (flow 4x pt minute ventilation) or 60L/min Accurate FiO2 |
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Typical High Flow Systems
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Venturi Mask- Smaller jet- greater velocity and more air entrained. Large jet- lower pressure/velocity, less air entrained and higher FiO2
Large Volume Nebulizers- varies FiO2 by air entrainment, disposable Face Tent, Briggs adapter, Trach Collar |
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Low Flow Systems
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Unable to deliver total minute ventilation (As min vent goes up, FiO2 goes down/As min vent goes down, FiO2 goes up)
No way to gurantee specific FiO2 |
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Typical Low Flow Systems
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Nasal Cannula
Nasal Catheter Transtracheal Oxygen Catheter |
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Reservoir Systems
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Gives pt extra pool to pull oxygen from
*NEVER run it less than 5L/min Ordered by Flow(L/min) Cannot give specific FiO2- varies w/ min ventilation and mask seal |
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Typical Reservoir Systems
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Simple Mask- 5-12L/min, 35-50% FiO2
Partial Rebreathing Mask- 6-10L/min, 35-60% FiO2, has reservoir bag Non-Rebreathing Mask- 6-10L/min or enough to keep bag partially inflated, 55-70% FiO2. Typical in CHF pt, High flow w/out intubating |
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Selection of Oxygen Systems
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Non-Intubated- Low flow systems(Nasal cannula) is most tolerated and should be first choice. Emergent care- simple, partial rebreathing, non-rebreathing are best for higher FiO2.
Intubated pt- High flow systems w/ humidity or aerosol |
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Hyperbaric Oxygen Therapy
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Delivery of supplemental oxygen at pressures greater than 1 atmosphere
-Reduces nitrogen bubbles in blood -Hyperoxygenation of blood (healing wounds) -Has effect on infections -Aids in formation of new capillary beds -Vasocontriction to help reduce swelling |
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Hyperbaric Oxygen Administration
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Multiplace Chamber-only pt breathes 100% O2
Monoplace Chamber- Small one person chamber containing 100% O2 |
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Indications for Hyperbaric Oxygen Therapy
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Air embolism- compressing bubbles to keep them small so they arent fatal
Carbon Monoxide poisoning- Removes carbon monoxide fastest from blood |
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Complications of Hyperbaric Oxygen Therapy
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Barotrauma (ear or sinus trauma, pneumothorax, air embolism)
Oxygen Toxicity (CNS affected) Fire (takes only a spark) |
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Heliox
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Mixture of helium and oxygen
Produces more laminar flow Diffuses 1.8x faster than O2 |
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Heliox Clinical Applications
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Partial airway obstructions
Acute asthma to decrease turbulent flow Diagnostic Pulmonary Function Tests |
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Heliox Contradictions
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Pt requires >60% oxygen- Heliox not efffective in concentrations <50%
Small airway diseases- Heliox has no effect bc small airways are typically laminar |
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Heliox Delivery Mechanisms
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Non-rebreathing mask- to spontaneously breathing pt, must multiply flow meter by 1.8 to get actual flow
Mechanically Ventilated- Cant tell exact volumes pt receives bc of the low density. Must check ABG O2. and CO2 levels to understand where your treatment is Aerosol- may allow for meds to reach deeper in the lungs. Effects nebulizer function though |
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Nitric Oxide Delivery (How it works)
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Diffuses into smooth muscle of pulmonary blood vessels
Results in smooth muscle relaxation reducing blood pressure and work of the right side of heart |
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Nitric Oxide Clinical Indications
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Hypoxic respiratory failure of the newborn- lowers pulmonary blood pressure of vessels
Post op (lung resection, heart/lung transplants, right ventricular failure, open heart surgery) |
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Nitric Oxide Delivery Systems
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INOvent- works in conjunction with ventilator
-Requires continuous monitoring |
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Nitric Oxide Complications/Precautions
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May form nitrogen dioxide when mixed with O2(toxic to body)
Met-Hemoglobin is produced when NO binds to hemoglobin (decreases oxygen carrying capacity of the blood) |
