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Theory 2
2 Theory
What is a Laminar Flow? | Smooth movement through cylindrical tubes; no impedant (smooth surfaces, consistent radius) |
What is Poiseuille's Law? | In Laminar; the relationship between pressure, resistance & flow through a tube (EG. breathing more when the diameter is reduced) |
What is the pressure related to in a laminar flow? | Pressure required is directly related to viscosity (thick/thin) and length of tube AND inversely related to radius |
What are the 3 interpretations of Poiseuille's Law? | 1. Greater the viscosity (thicker fluid), the greater the pressure required to move it 2. Resistance through a tube is proportional to it length (P required for flow increases when tube length does) 3. Small changes in radius = large decreases in flow |
What is a Turbulent Flow? | Molecules form a irregular eddy currents in a chaotic pattern; usually @ higher gas flowrates and in larger tubes. - Predicted by Reynolds number |
When will Turbulent Flow occur? (3) | 1. Increase in linear velocity or gas 2. Increase in density of gas 3. Increase in radius of tube (more room for gas to go in circles) |
What is Reynold's number? | In turbulent; the ratio of inertial force required compared to the viscous force of the substance |
What happens in RN when the density & radius increases? | + density = + turbulence = +NR; + radius = + turbulence = +NR |
What is a Transitional Flow? | A mixture between laminar and turbulent flow |
What is the pressure required to move gas? | The sum of above pressures |
What is the respiratory airway conducting system for laminar and turbulent? | Laminar flow = pressure varies linearly with flow (pulling gas in) Turbulent flow = pressure varies exponentially with flow |
What is flow? | Volume of fluid per unit of time; L/sec or L/min |
What is velocity? | Linear distance per unit of time; cm/sec |
How are flow and velocity linked? | Linked by cross-sectional areas of tube (tree roots); varies inversely with cross-section area of tube (EG. reduce area by half = 2x increase velocity) |
How are area and velocity linked? | The smaller the area/diameter or radius = the faster the flow goes |
What is the Bernoulli Effect? (3) | 1. If tube diameter unchanged, P will drop over tube length 2. Fluid passing through tube that has constriction will have a P drop 3. Fluid that flows through constriction increases its velocity while lateral wall P decreases |
Bernouilli Effect example with picture | With the series of tubes; when theres a smaller diameter = the flow in that one tube will decrease & the P decreases (pulling more fluid in) but V increases |
What is an entrainment? | When you have an opening distal to the constriction you can pull in ambient air too |
What happens when you have a larger jet? | Decrease in V & entrainment (not pulling in as much; less dilate) |
What is an Air Injector? | Taking gas and putting it through a tube |
What is a jet? | In an air injector; how big the opening part of the end is |
What is a ventri tube? | A modified entrainment device; widens just after the jet or nozzle. Will restore the fluid pressure again (since it decreases due to the jet) |
What does Fluidics means? | Using hydrodynamics principles in flow circuits |
What is the Coanda effect? | Wall attachment; decrease in later wall pressure after gas flow passes through narrowed jet orifice; additional opposing flows will cause a change in direction of original flow |
When is the Coanda effect applied? | Applied in mechanical ventilators and other equipment to avoid/bypass electronic devices |
How much does oxygen occupy in the Earth's crust? | 50% |
What is considered an Oxygen enriched environment? | >23% oxygen = fire hazard |
What are the 4 Clinical indications for Oxygen Therapy? (when to know if they need it) | 1. Low blood oxygen levels: hypoxemia 2. Severe trauma: not as much circulating blood 3. Minimize cardiac workload (not providing as much oxygen) 4. Short-term prophylactic use |
What is the level of a considered hyperoxemia, normoxemia, and a hypoxemia? | >100 mmHg; 80-100; 60-70 mmHg |
What does FiO2 mean? | Fraction of inspired O2: .21-1.0 (instead of saying 21%) |
What does PaO2 mean? | Partial pressure O2 in arterial blood; greater than 60 mmHg |
What does SaO2 mean? | Saturation of hemoglobin with O2; >90% (60mmHg) |
What does SpO2 mean? | Saturation of pulse oximetry; oxygen level being read at pulse |
What is the normal level of SaO2? | 90% (anything lower = bad) |
What should you do during a head injury? | Keep PaO2 levels high> induce cerebral vasoconstriction> reduce cerebral blood flow> reduce intracranial pressure> protect injured brain |
What does Short term prophylactic use mean? | Post-anaesthesia/surgical recovery - until patients awake, keep adequate respiratory rate |
What are 2 examples of minimizing cardiac workload? | Congestive Heart Failure & Myocardial infarct (heart attack) |
What happens during a Myocardial infarct? (infarct = dead tissue from lack of blood) | High FiO2s for 24-48 hours to decrease spread of infarct |
What are the 4 Complications of O2 Therapy? (what can happen when giving) | 1. Oxygen Toxicity 2. Depression of Ventilation 3. Absorption Atelectasis (partial of complete collapse of lung) 4. Retinopathy of Prematurity (infants) |
What is Oxygen Toxicity? | Extra amounts to tissues; Over-production of Oxygen free radicals |
What does Oxygen Toxicity do and where does it affect? | Damages or kills cells; affects the lungs and CNS primarily |
How does Oxygen Toxicity affect the lungs? | Destroys alveolar-capillary membrane; leads to further low blood oxygen |
What are the determining factors of Oxygen Toxicity? | PaO2 & exposure time (short time=no effect) |
What happens in 0-12 hours of 100% O2? (oxygen toxicity) (3) | No change in lung function; tracheobronchitis (hoarse voice, sore throat) & chest pain |
What happens in 12-24 hours of 100% O2? (oxygen toxicity) (1) | Decrease vital capacity (because of damaged alveolar-capillary membrane) |
What happens in 24-30 hours of 100% O2? (oxygen toxicity) (3) | - Decrease in lunch compliance - Increase P(A-a)O2 (not good diffusion) - Decrease exercise PO2 (can't really tolerate it) |
What happens in 30-72 hours of 100% O2? (oxygen toxicity) (1) | Decrease diffusing capacity |
What is a Depression of Ventilation? (harder to breathe) | Lung tissue damages so have high PaCO2 levels & low PaO2; breathing depends on PaO2 |
What happens if PaO2 levels too high in a depression of ventilation? | Brain won't respond; therefore decrease in respiratory rate...Have to be careful how much you give (start low then high) |
What happens when FiO2 levels are > than 50%? (5) | 1. Alveolar N2 will drop 2. Venous blood levels of N2 also fall 3. All gases from alveoli diffuse into venous system from high P 4. Atelectasis 5. Hypoxemia - from shunting |
What happens during a Retinopathy of Prematurity (ROP)? | Too high PaO2 levels over long period of time = causing constriction of vessels around the retina |
What does ROP cause? (4) | 1. Vessel necrosis (b/c of constriction, no O2 so tissue dies) 2. Increased formation of new vessels 3. Haemorrhaging, which causes scarring behind retina 4. Retinal detachment and blindness |
What are the 3 Physiological Assessments for Therapy? How can you tell if they need it | 1. Laboratory measurements (ie. PaO2, SaO2, hemoglobin, hematocrit) 2. Clinical problem or condition - look @ the patient/visual 3. Clinical assessment and/or patient symptoms - assessment, lab data, physiological state |
What are the 2 types of a Non-Specific FiO2? | 1. Low Flow or Variable 2. Resevoir |
Flow for Low-Flow/Variable? | < 8 LPM |
Why can't FiO2 be predicted in a low-flow/variable? | Because it has such a low flow rate and we need at least 30-40 LPM; therefore need to entrain some ambient air |
What is a Nasal Cannula? | 2 prongs that sit at the base of the nose |
Flowrate & FiO2 for Cannula? | 1-6 LPM & .24 - .44 |
What is the flowrate that requires a humidifier in a Cannula? | >4 LPM |
What can happen if you set the flow rate too high in a cannula? | Can cause turbulent which causes back flow |
What are the Clinical Uses for a Cannula? | 1. Continuous Delivery - short/long term 2. Low percent requirements 3. Adults, Children, Infants/Premies |
What is the advantage to a cannula? | Easy to apply; well tolerated |
What are the 2 disadvantages to a cannula? | 1. Low flow rate 2. Can cause nasal dryness & bleeding |
What is a reservoir? | Mechanism that gathers and stores O2 between breaths |
Why is a reservoir system still unpredictable with FiO2 levels? | Because we're breathing in extra oxygen from the reservoir |
What are the 2 types of reservoirs? | 1. Reservoir cannula/pendant 2. Reservoir masks |
What are the 3 types of a reservoir mask? | 1. Simple 2. Non-Rebreathing 3. Hi-Ox80 |
How much Oxygen does a Reservoir Cannula store up to? | 75% |
Flow rate & FiO2 levels of Reservoir Cannula? | 1-4 LPM and .22-.35 |
How much does a cannula reservoir store during expiration? | 20 ml O2 |
How much does a simple mask - reservoir mask - store? | Stores 100-200 ml of gas for the next breath in |
Flow rate for simple mask reservoir & FiO2? | 5-10 LPM & .35-.50 |
What are the 3 clinical uses for a simple mask? | 1. Emergency/post-op recovery 2. Short-term 3. Moderate oxygen requirements |
What are the 3 advantages to a simple mask? | 1. Quick, easily applied 2. Adults, children, infants 3. Inexpensive |
What are the 2 disadvantages for a simple mask? | 1. Uncomfortable 2. Remove for eating |
How much does a reservoir bag hold in a Non-Rebreathing Mask? | 300-500 ml |
Where are the Directional valves placed in a Non-Rebreathing Mask? | Between bag & mask on exhale ports |
What do the Directional valves do/prevent in a Non-Rebreathing Mask? | Prevent rebreathing into reservoir or dilution from ambient air |
Flow rate and FiO2 for Non-Rebreathing Mask? | 6-10 LPM & .6-.8 + |
How much oxygen does the mask hold in a Non-Rebreathing Mask? | 100-200 ml |
What is the safety concern for a Non-Rebreathing Mask? | No access to ambient air if directional valves stick closed or insufficient O2 flow THEREFORE must remove one valve |
What are the 3 clinical uses for a Non-Rebreathing Mask? | 1. Severe emergencies 2. Short-term 3. High FiO2s available (100% in bag) |
What are the 2 advantages in a Non-Rebreathing Mask? | 1. Quick, easily applied 2. High oxygen levels |
What are the 2 disadvantages to a Non-Rebreathing Mask? | 1. Must meet patient's PIF or FiO2; unpredictable and can vary 2. Can't put humidifier on therefore dry |
Flow rate & FiO2 for Hi-Ox80 Mask? | 8 LPM & >80% |
How does a Hi-Ox80 Mask meet the FiO2 and PIF for a patient? | From the reservoir bag |
What kind of style is the Hi-Ox80 Mask? | Non-Rebreathing Style |
What is the Hi-Ox80 Mask good for? | Good for filtering out the air from viruses/diseases |
What are Specific FiO2: High Flow systems mainly used for? | Acute Care Therapy |
How does the Air Entrainment vary? (3) | 1. Size of Jet 2. Velocity of Oxygen at the jet 3. Size of entrainment port |
How much does a Specific FiO2: High Flow system must be able to provide? | > 40-60 LPM since they're dealing with very sick patients |
What happens to the FiO2 if the mask system cannot meet the PIF? | Get ambient air to meet the PIF, this will dilute the O2 bringing down the FiO2 |
What is the Air:O2 Equation? | Litres Air: (100-O2) Litres O2: (%O2 - 21) |
How do you calculate the total output flow? | Add the air:oxygen ratios together (ie 3:1 = 4), then multiply the sum of ratio by the source of O2 input flow/flowrate (given) |
What are the 2 types of Specific O2 devices? | 1. Masks 2. Large Volume nebulizers |
What are the 2 types of Air-Entrainment Masks? (High-Flow) | 1. HAFOE/Venturi Mask (one that looks like elephant) 2. Oxy-Mask |
What is the FiO2 for a HAFOE/Venturi Mask? | 0.24-0.50 |
What is the humidity requirement for a HAFOE/Venturi Mask? | >4 LPM, vapour or aerosol droplet |
In an HAFOE/Venturi Mask, is it the entrainment or jet that you can change? | The jet; the higher the jet (ie 40) the more FiO2 since not a lot of ambient air going through |
What is the FiO2 &flow available for a Oxymask? | 0.24-0.90 & 1-40 LPM |
How does the Oxymask get its humidity? | Vapour only; no aerosol droplets |
What type is a Air-Entrainment Jet Nebulizer? | A specific FiO2 - high flow - Large Volume Nebulizer |
In a Air-Entrainment Jet Nebulizer, what is the fixed mechanism? | Jet is fixed; entrainment is changeable |
What is the FiO2 and flow rate for a Air-Entrainment Jet Nebulizer? | 0.28-1.0 (pure gas) & 5-10 15 LPM (usually 10-15) |
How do you add humidity into an Air-Entrainment Jet Nebulizer? | By Aerosol Droplets |
What happens if the window is more open in an Air-Entrainment Jet Nebulizer? | More of an open window = more ambient air that can come in & lower FiO2 |
What is the problem with a Air-Entrainment Jet Nebulizer? | Might not be able to meet the patient's PIF |
What are the 3 possible solutions to meet the patient's PIF in an Air-Entrainment Jet Nebulizer? | 1. Have 2 nebulizers to increase LPM 2. Add reservoir tubes into the mask (horns of plenty) 3. Use High-Flow Devices |
What happens if you has reservoirs onto the Air-Entrainment Jet Nebulizer? | Less ambient air to go in (less room) |
What are the 2 types of High-Flow Devices that you can add to an Air-Entrainment Jet Nebulizer? | 1. LVN 2. High Flow Nasal Cannula |
What does HBOT stand for? | Hyperbaric Oxygen Therapy |
What atmospheric pressure does a HBOT deliver at? | 2-3 atm/ATA for low/acute illnesses; 6 ATA for more severe diseases/issues |
What are the 3 things that you would use a HBOT for? | 1. Trapped Gases (Boyle's Law) 2. Hyperoxia 3. Increases O2 to tissues |
How does a HBOT help with Hyperoxia? (4) | 1. Enhanced Immune Function 2. Wound healing 3. Improved Vascular Tone 4. Binding w/ Hemoglobin |
Is Decompression Sickness considered an Acute or Chronic Illness for HBOT? | Acute |
Is Air Embolism considered an Acute or Chronic Illness for HBOT? | Acute |
Is CO poisoning considered an Acute or Chronic Illness for HBOT? | Acute |
Is a Crush Injury considered an Acute or Chronic Illness for HBOT? | Acute - potentially crushed capillaries |
Is Clostridial Gangrene considered an Acute or Chronic Illness for HBOT? | Acute - bacterial infection |
Is Necrotizing soft tissue infections considered an Acute or Chronic Illness for HBOT? | Acute - flesh eating bacteria |
Is Ischemic Skin Grafts considered an Acute or Chronic Illness for HBOT? | Acute |
Is a Non-Healing wound considered an Acute or Chronic Illness for HBOT? | Chronic |
Is Refractory Osteomyelitits considered an Acute or Chronic Illness for HBOT? | Chronic - bone infection |
Is Radiation Necrosis considered an Acute or Chronic Illness for HBOT? | Chronic - death of cells from radiation |
What happens to your joints during a Decompression Sickness? | The gas bubbles become too large and makes the joints lock |
What is the prevention mechanism for Decompression Sickness? | Slow ascent - 10m/min |
What are the 2 treatment options for Decompression Sickness? | 1. 100% O2 2. HBOT - so then they can control the pressure |
What is Henry's Law in terms of Hyperoxia? | O2 carried in solution (blood) is directly proportional to the partial pressure of the gas that the solution is exposed of |
What is Air Embolism? | Air getting into wounds or bloodstream, during a surgical procedure, that then goes to the brain |
What 2 things can an Air Embolism cause? | 1. Neurological damage 2. Sudden Death |
How does a HBOT treat an Air Embolism? | Reduces the volume of bubbles while oxygenating the local tissue |
What are the 2 types of an HBOT Chamber? | 1. Single Chamber - Monoplace Chamber 2. Multiplace Chamber - Fixed Hyperbaric Chamber |
What are the 2 rooms in a Multiplace Chamber? | 1. Decompression Chamber 2. Ante Chamber - where they work |
How much oxygen does a patient breathe in in a HBOT Chamber and how? | 100% O2 through a mask |
What conditions is a Single Chamber and a Multiplace Chamber used for? | Single - Acute Multi - Chronic |
What are the 5 different Complications with HBOT? | 1. Barotrauma 2. Oxygen Toxicity 3. Fire Hazard 4. Sudden Decompression 5. Physiological (IE cardiac output) |
What is a Barotrauma? | Trauma due to increased pressure in lung |
What can Barotrauma cause? | Alveolar Over-Distension/pneumothorax; from lung expansion & air inbetween lining of lungs |
What causes a sudden decompression in the HBOT Chamber? | Equipment failure |
What are the 3 systems used for Home Oxygen Therapy? | 1. Molecular Sieve Oxygen Concentrator (pellets) 2. Liquid Reservoir Systems - LOX (mini liquid system) 3. Electronic Oxygen Conserving Device |
What did the 1980 LOT Studies find with no oxygen after treatment? | 20% survival |
What did the 1980 LOT Studies find with 12h oxygen after treatment? | 40% survival |
What did the 1980 LOT Studies find with >18h oxygen after treatment? | 60% survival |
What is the physiological criteria for home oxygen therapy? (when to know if they need it) | Blood <60 mmHg (PaO2) & <90% (SaO2) @ room temp, rest, w/ 6 min walk, or if they have right sided heart failure (COPD) |
What are the 3 types of funding for a patient w/ Home Oxygen Therapy? | 1. Ministry of Health 2. Private Insurance 3. Other - pay yourself |
How do the Ministry of Health pay? | >65 y = ODB = 100% <30 y = ADP = 75% any age w/ longterm disability = 100% |
What are the 6 things a RT must do when they are assigned a new patient? | 1. See if they need it 2. See what type they need 3. Ensure their house is safe 4. Set it up/give education 5. Checkup whenever needed 6. Liaison w/ health care team |
How does the Molecular Sieve Oxygen Concentrator work? | - Separates gases by passing ambient air through a bed of NaAl pellets OR Zeolite - Pellets trap all gases except for O2 |
What are the 3 advantages to a Molecular Sieve? | 1. Cost efficient for partial and continuos use 2. Safe - low pressure and alarms 3. Low maintenance required - replace pellets after <85% purity |
What are the 4 disadvantages to a Molecule Sieve? | 1. Noisy & generates heat 2. Requires electrical power & need cylinders for incase of power outage 3. Low FiO2 <.40 4. Need cylinders for out of home |
What are the 3 alarms for in a Molecular Sieve? | 1. Internal pressure exceeds >25 psi 2. Internal pressure drops <5 psi 3. If O2 stops flowing out - power outage |
Besides the alarms, what other 2 things are used as a safety mechanism for the Molecular Sieve? | 1. DISS Threading 2. Optional - Low O2 alarm |
What does the patient need to do if they need to go somewhere but they use the Molecular Sieve? | Would have to fill a E or D size cylinder and go out; some Molecular Sieves will fill it for you |
Why can't the Molecular Sieve ever flow out 100% O2? | Because very small molecules of other gases are still able to get out |
What is the FiO2 for a patient for a Molecular Sieve? | .22-.40 |
What flow rate requires humidity in a Molecular Sieve and why? | >2LPM because as the ambient air is being compressed into O2 it generates heat, therefore the O2 that comes out is warm and can cause dryness in the patients nasal cavity |
How does the 4 way solenoid work? | 1. Pulls in ambient air 2. The 4 way solenoid determines where the air goes 3. Air either goes through sieve bed into reservoir 4. Then every 15 seconds the air switches between the 2 canisters |
What is the sieve canister pressurized to? | 20 psi |
Why does the air flow direction switches every 15 seconds? | So then trapped gases can be purged out through depressurization of first canister |
How much of the oxygen is used for cleaning the other canister in the Molecular Sieve? | 80% |
How much of the oxygen is used for actual patient use in a Molecular Sieve? | 20% |
What reduces the pressure in the Molecular Sieve and what does it reduce it to? | PRV in the Accumulator, reduced to 8-10 psi |
What is the flow rate for the Molecular Sieve? | 0-5LPM |
How much does 1 cu ft LOX = in cu ft gaseous O2? | 860 cuft gaseous O2 |
How much is usually in a reservoir base canister/dewars? | 20-40L |
What is the head pressure in an LOX? | 20 psi |
What is the flowrate for a LOX? | 1-8 LPM |
What happens when the head pressure drops by 0.5 in a LOX? | The Economizer Valve closes access to gas, then the liquid gets drawn in |
What happens when the liquids gets withdrawn in a LOX? | It will go up the tube that leads to to the outlet, bc it is exposed to ambient air the tube is partially warm, therefore the liquid gets converted to gas as it goes up |
When does the Primary Pressure Relief go off? | When the HP exceeds +2 psi |
When does the Secondary Pressure Relief go off? | When the HP exceeds +10 psi |
What does the Vent-to-FIll Valve do? | Tap that you turn to open/close; Transfers liquid from large bulk supple into canister |
What is considered the 4th safety mechanism in the LOX? | The DISS Threading |
Why do you have to open the Vent-to-Fill Valve when filling? | Open it so then when the liquid starts pouring in it can push out the gas that was already in there |
How much is usually in a LOX Portable System? | 0.5-2 L |
What are the 2 things that a LOX Portable System doesn't have? | 1. Economizer Valve 2. DISS Threading |
What are the 2 ways you can calculate the Duration of Flow in the LOX? | 1. By weight of reservoir 2. By volume in L |
How do you calculate the DOF by weight? | ___ x 2.5lb (=lb) the multiply that by 344 L Gaseous O2 The divide by flowrate |
How do you calculate the DOF by volume? | ____ x 860 cuft / flowrate |
When does a O2 Conserving device start to give gas during a demand-flow? | in the first 25% of time |
What are the 4 steps in a O2 Conserving Device | 1. Patient makes inspiratory effort (- pressure) 2. Flow sensory senses air movement 3. Solenoid valve opens 4. Measured 'pulsed dose' based on selected setting |
What does the size of dose in a O2 Conserving Device depend on? | On the prescribed flowrate |
What is the flowrate for a O2 Conserving Device? | 1-4 LPM |
Why can't you use a O2 Conserving Device at night time? | Poor inspiratory effort |
What is the purity of a O2 Conserving device and why? | <90% bc of smaller sieve pellets |
When would you use a continuous flow in a O2 Conserving Device and at what flowrate? | @ 2LPM - when the patient has trouble breathing (senses) |
What 2 devices need a rest and 6 min walking test? and why? | 1. O2 Conserving Device 2. Home Oxygen Therapy Bc allows them to see if it works while they are walking |