Quiz 2 Prep - flow devices and such Flashcards
1
Q
Define the term high flow oxygen delivery system
A
High flow oxygen systems are capable of meeting all of a patients inspiratory flow demands.
2
Q
List 2 examples of high flow oxygen delivery systems
A
High flow Cold Neb (misty-ox)
High Flow Nasal Cannula (optiflow)
3
Q
When would you use a cold nebulizer?
A
Post extubation
Dry throat/nose
Secretions
4
Q
Which device is the high flow cold neb
A
Green cap
5
Q
When would you use a high flow neb?
A
Sat less than 86%
Used when FiO2 is greater than 32
6
Q
Criteria and goals for high flow neb use
A
Goal is to achieve fixed performance (60 or greater)
Flow always set to 40 LPM
7
Q
Flow through a tube is directly proportional to
A
Radius
8
Q
What are the goals of oxygen therapy? (3)
A
To correct documented arterial hypoxemia or suspected tissue hypoxia.
To decrease hypoxia
To prevent/minimize the increased cardio-pulmonary work load associated with compensatory mechs related to hypoxia.
9
Q
What does your body do when you are low on oxygen?
A
Respiratory rate increases
HR increases
Cardiac Output increases
Blood pressure increases
-Pulmonary reflex
10
Q
General Indications for oxygen therapy (hospital)
A
PaO2 < 60mmHG
O2 Sat < 90 (92 in some cases)
11
Q
Indications for oxygen therapy in acute situations (hospital)
A
Suspect hypoxemia
severe trauma
MI
12
Q
Indications for O2 therapy as a short term preventative measure? (hospital)
A
Post anethesia
13
Q
Precautions of O2 therapy?
A
Chronically elevated PaCO2
High FiO2
absorption atelectasis
Retinopathy of prematurity (ROP)
14
Q
Absorption atelectasis
A
A loss of lung volume caused by the resorption of air within the alveoli.
Ventilation is blocked = less gas enters
less gas is removed by uptake blood
15
Q
Retinopathy of prematurity (ROP)
A
eye diseases in babies caused by too much O2
O2 causes abnormal blood vessels to grow in the retina = blindness.
16
Q
What happens when a patient with chronically elevated PaCO2 is continually given high amounts of O2?
A
They lose their drive to breath
also known as
“Hypoxic drive”
17
Q
Paraquat poisoning
A
Damage to lining of lungs and exacerbated in the presence of O2.
18
Q
Laser bronchoscopy
A
Tracheal fire
immediate-acting, palliative, or adjunctive therapy used to relieve central airway obstruction
19
Q
Which indications for O2 therapy are needed in community?
A
Same as hospital
+
Home care O2
-need proof of severe lung disease
20
Q
Which systems prevent the most risk of infection
(rank them)
Simple low flow
heated humidity
bypass URT
A
low = Simple low flow
medium = heated humidity + aerosol generators
High = bypass urt
21
Q
Risks of heated humidity systems
A
-heated humidity is a breeding ground for bacteria
-water needs to be sterile
-hand hygiene all the time
22
Q
Risks when patients have a bypassed URT
A
-at risk because bypassed their normal line of defence
-ETT
-trach
23
Q
why must equipment that must be changed or cleaned regularly
A
Ventilator acquire pneumonia (VAP)
24
Q
What is O2 toxicity?
A
Prolonged exposures to high levels of O2.
Requires prolonged exposure to FiO2 of 0.6
(can very due to injury)
Changes can happen faster under hyper-baric conditions
25
What increases susceptibility of oxygen toxicity?
Advanced age
Catecholamines
Bleomycin
Steroids
Hyperthermia
Hyperthyroidism
Premature birth
Vitamin E
Protein Deficiency
26
What decreases susceptibility of oxygen toxicity?
Youth
Hypothermia
Prior lung damage
Anti-oxidants (glutathione, increased VitC, Vit E)
27
Exposure to 100% O2: 0-12 hours (early)
-Retro-sternal chest pain
cough
dyspnea
emesis,
low energy
28
Exposure to 100% O2: Late
Cyanosis
Frothy sputum
Increased WOB
Respiratory failure
29
O2 overexposure: once past the 24 hours mark what is expected?
decrease in lung compliance
A-a dO2 increases
Decrease in DLco
(diffusing capacity for carbon monoxide )
30
bTreatments for O2 toxicity?
Diuretics and electrolytes for fluid management
Antibiotics and anti-pyretic
Corticosteroids for inflammation
Analgesics for comfort
Bronchodilators for bronchospasm induced dyspnea
Nutritional support to minimize muscle atrophy
31
Prevention of O2 therapy
carful admin (safe upper limit = 250-280mmHg)
Regular ABG/oximetry of patients with high FiO2 (>0.5)
ingestion of antioxidants
intermittent exposure
32
two basic O2 therapy devices
Low flow: gives variable FiO2
High flow: fixed performance
33
What is fixed performance?
everything your patient is breathing in comes from the device and giving a fixed FiO2
34
Nasal cannula flow?
1-6 lpm
35
What are the advantages of using nasal cannulas?
-Wide variety of size
-Very easy to master for disadvantaged patients
-Light weight
-Economical
-Disposable
-Patients tolerate prongs better than mask
36
What are the disadvantages of using nasal cannulas?
-Excessive flows can cause patient discomfort and noise (max. 6LPM)
-Easily dislodged
-Can be problematic if patient has deviated septum, severe nasal mucosal edema, nasal drainage, nasal polyps, facial skin irritation
-Can cause ear irritation
-Does not respond to increased RR or demand
37
Are nasal cannulas variable or fixed performance?
FiO2 is variable and unpredictable
38
What are the approximate FiO2 at given flow rates with nasal cannula?
Every litre is increasing FiO2 about 4%
1 LPM = FiO2 0.24
2 LPM = FiO2 0.28
3 LPM = FiO2 0.32
4 LPM = FiO2 0.36
5 LPM = FiO2 0.40
6-8 LPM = FiO2 0.44-0.50
These may be somewhat optimistic as they require perfect conditions
39
Simple Mask
-Fits over the mouth and nose of the patient with no valves or reservoir bag
-Exhaled gas is vented through holes in the side and spaces around the edge of the mask
-The inside volume of the mask may contain exhaled gas and therefore be considered dead space
-Various sizes, cannot deliver high FiO2s
-May trap vomit and lead to aspiration
40
Why does the minimum flow of a simple mask start at 5LPM?
The flow should be sufficient to flush CO2 from the mask
The inside volume of the mask may contain exhaled gas and therefore be considered dead space
-You sort of breathe back the CO2 due to anatomical reservoir
41
what are the aprox FiO2 at given flow rates with simple mask?
5-6 LPM = FiO2 0.40
6-7 LPM = FiO2 0.50
7-8 LPM = FiO2 0.60
Higher flows do not seem to raise FiO2 appreciably
Still highly variable under perfect conditions
42
Face tent
Very variable performance and don't really know what FiO2 the patient is getting
-Similar performance to simple O2 mask
-Pouch like design allows patients t get similar flows as mask but no part touches upper part of the face
-May be useful in facial trauma patient or severe claustrophobia
43
Partial Rebreather Mask (PRB)
-Very hard to judge FiO2
-Modified non-rebreather mask
-3 disk shaped one-way leaf valves removed
-Reservoir bag attached
-1st third of exhalation should fill the reservoir with high FiO2 gas from patient's anatomical dead space
-Excess gas vented to atmosphere
-During inhalation, gas from reservoir & gas flowing from O2 source & atmospheric gas all enter the patient's flow
44
What are the pros and cons of the [PRB]
Partial rebreather:
-Higher FiO2 than simple mask
-Minimum flow setting is about 10LPM to disallow complete collapse of reservoir bag on inhalation
-Maximum FiO2 is no higher than 0.6-0.7 depending on patient's ventilatory pattern
45
Why is entrainment useful?
It allows us to deliver precise O2 concentration levels with simple devices by mixing O2 with entrained room air.
46
What is the bases of all entrainment devices (how they basically work)
If the sum of the KE and PE must equal, as fluid flows through the restricted area, velocity will increase and therefore lateral pressure will decrease
47
Entrainment: what happens when velocity increases enough to decrease lateral pressure below atmospheric pressure?
Creates negative pressure.
when this happens, tubes are often placed distal to the restriction to pull more fluid/gas into the stream flow
48
The amount of fluid/gas entrained depends on?
size of entrainment port
size of jet
49
Jet size in relation to entrainment
Jet size has an inverse relationship with entrainment.
-smaller the jet, the faster the velocity, the more entrainment
-the bigger the jet, the slower the forward flow, the less entrainment
50
Entrainment ports in relation to entrainment
Entrainment ports have a direct relationship with entrainment.
-the bigger the entrainment port, the more entrainment
-the smaller the entrainment port, the less entrainment
51
Things that will increase entrainment
smaller jets
bigger entrainment ports
increase in total flow
52
Things that decrease entrainment
bigger jets
smaller entrainment ports
decrease in total flow
53
what happens to FiO2 if there is an increase in entrainment
increase in entrainment means more room air diluting the O2, therefore FiO2 will decrease.
54
Venturi principle
Pressure drop across a restriction can be restored to pre-restriction pressure if there is a gradual dilation of the tube distal to the restriction.
55
Venturi principle : what happens when a restriction is gradually dilated with the addition of jets?
The addition of the jet speeds up the flow, causing a pressure drop and creating a sort of vacuum and back pressure pushes against forward flow slowing down entrainment
If there is a build-up of pressure downstream from the entrainment port, there will be a decrease in the amount of fluid or gas entrained.
--> back pressure will slow down the forward pressure, slowing down entrainment which would INCREASE FiO2.
56
Pitot principle
Pitot tubes don't restore the pressure to pre-restriction pressures
Keeps fowrward flow fast, keeps entrainment high, resist affect of back pressure
57
Venturi vs Pitot
Venturi
-can restore the pressure to pre-restriction pressure if there is a gradual dilation (≤15°) of the tube distal to the restriction.
-back pressure pushes against forward flow slowing down entrainment
Pitot
-does not restore the pressure to pre-restriction pressure
-keeps pressure low, forward flow fast, entrainment high, resist affect of back pressure
58
What is hyperbaric oxygen therapy [HBOT]
HBOT is the use of 100% oxygen at higher atmospheric pressure than is normal to treat some medical problems.
HBOT is used in combination with antibiotics, dressing changes, and surgery to improve healing.
59
What are some possible complications resulting from HBOT?
Pulmonary barotrauma
-Damage to equipment with closed gas-filled spaces such as Pacemaker/defibrillator and breast implants
-Need to check pacemaker what it is rated for HBOT
Ear, sinus, or dental barotrauma
-Ear trauma is the most common. Need to ensure the patient does not have ear or sinus problems so they can equalize their ears
-If patient has a crown or dental work filled with gas, it can pop off
60
The role of Boyle's Law in HBOT
It applies HBOT for treatment for accidents/events that result in intravascular and/or tissue gas emboli:
-Decompression Sickness
-Latrogenic Arterial Gas embolism
-Pneumotosis Cystoides Instestinalis (PCI)
61
Rapid Decompression
Nitrogen bubbles come out and form in bloodstream - plasma (interrupt blood flow) and can go to your brain
-like having a stroke because interrupting blood flow to the brain
Bubbles interrupt flow to the heart
-like getting an MI
The lungs expand and eventually rupture
-like getting a pneumothorax
62
HBOT and Henry's law
-At constant temperature, more gas is dissolved into a liquid by increasing the pressure of the gas.
-By increasing the pressure in the HBOT chamber, more oxygen can be dissolved in the plasma.
63
HBOT and Boyles law
PV = K.
As the pressure increases, the volume of the bubble decreases.
-When your body is under immense pressure, the nitrogen is forced into solution (into blood and tissues).
-As you decompress, nitrogen is forced out of the solution
64
What is the equation for content of arterial oxygen?
CaO2 = (Hb x 1.34) x SaO2 + (PaO2 x 0.003)
65
Equation for delivery of O2?
DO2 = (CAO2 x 10) x Q
66
Bourdan gauge with thorpe tube: are they back pressure compensated?
Yes
67
Hyperbaric Medicine's Mechanisms of Action
Direct Pressure (not an O2 dependent process)
Hyper-oxygenation
Angiogenesis
Anti-microbial
Toxicological Activity (e.g. CO poisoning)
Vasoconstriction
Blunting of ischemia-reperfusion injury (wound care)
68
What changes can be observed in a patients content of arterial oxygen when put in a hyperbaric chamber?
Oxygen dissolved in plasma increases significantly
-increases carrying capacity in a healthy individual but almost 40%
69
HBOT and toxicology activity
Used as treatment for CO poisoning
-Hypoxemia caused by CO binding to hemoglobin in place of O2 binding
-Co has 210x more affinity than oxygen for Hgb
Brain is most susceptible to CO with cellular injury
-avoid neurological issues by treating with 3 treatments over 24 hrs.
CO Half life (the amount of time it takes to drop the initial CO to half)
-Air breathing: 5-6 hrs
-Atmospheric O2: 75 mins
-HBO at 3ATM: < 30 mins
70
Angiogenesis
Sprouting new blood vessels from pre-existing blood vessels (previously damaged by disease or injury)
Treatments for:
-Deficient soft tissue wound healing
-Late radiation tissue injury
71
Antimicrobial Properties
Treatments for:
-Clostridial perfingens infections
-Necrotizing soft tissue infections
-Chronic refractory osteomyelitis
-Selected brain abscesses
72
How does HBOT treat compromised/occluded blood flow?
Vascular damage = decreased blood flow = decreased oxygen delivery to that area = increased chance of infection
If an area is compromised/occluded, RBC can't get past but plasma still flows through the damaged vessel.
How HBO treat:
HBOT increases the amount dissolved in plasma and because of new pathways through angiogenesis
73
HBOT: Oxygen and Wound Repair
Local Hypoxia
-results from tissue injury
Local Ischemia
-poses a threat to healing and infection
Vascular Endothelial Growth Factor (VEGF)
-promotes closure of chronic hypoxic wounds
-promotes vascular permeability VEGF levels increase significantly with daily HBOT
VEGF is critical to new vessel formation
-its activity only initiates formation of immature vessels
-for functioning vessels, VEGF must work in conjunction with angiopoietins
74
Absolute contraindications to HBOT
Untreated Pneumothorax
-will expand and pop
Bronchgenic Cysts
75
Adverse Side Effects of HBOT
Decompression Sickness
Tympanic Membrane Damage
Oxygen Toxicity
76
Prohibited Items
Cannot take anything in
No lotions, sunscreen, hair preparations, makeup, dentures, synthetic hair, petroleum or alcohol based dressings, velcro, flammable materials, unapproved fabric, etc.
Patient can only enter with what is supplied to them
-100% cotton gown (no pockets)
-one sheet
-Sippie cup with only water
All measure to reduce any chance of spark or static
77
What measures are taken to prevent any chance of static electricity?
Humidity in the room is kept at > 50%
The patient wears a grounding bracelet
78
Unapproved (Off Label) Uses for HBOT
The following don't show much improvement with HBOT Multiple Sclerosis
Cerebral Palsy
Autism
Parkinson's Disease
Fibromyalgia
Concussion
Brain injury
Spinal injuries
Cancer
The following are somewhat more receptive and show improvements
Anti-aging therapy
Long COVID
Sports injuries
79
How do you know if a device is back pressure compensated?
A device is back pressure compensated when in the face of back pressure, indicated litre flow remains accurate
Indicated flow = Actual Flow
80
Which device(s) is back pressure compensated?
Newer Thorpe tubes
Indicated flow = Actual flow
81
Which device(s) is not back pressure compensated?
Bourdon Gauge
Indicated flow > Actual Flow
Older Thorpe tubes & Flow Restrictor
Indicated flow < Actual flow
82
Why is a Bordon type flow meter not back pressure compensated?
Because gauge only measure pre-orifice pressure, back pressure reduces flow but flow meter valves doesn't change.
If you occlude the orifice, it will still display the indicated flow even if it's actually delivering nothing.
83
How can you indicate if a Thorpe tube is compensated or uncompensated?
If the needle valve is before the actual tube, it is uncompensated.
If the needle valve is after the actual tube, it is compensated.
84
What are blenders?
A blender is a device that uses approximately 50 PSI gas sources
-typically air and oxygen
-blend together and deliver a specific FiO2
Blenders can produce very high flows and FiO2 ranges of 0.21-0.1
Blenders are typically composed of three systems
Pressure balancing module
-consisting of reducing valves that equalize the inlet pressure of air and oxygen
Proportion module
-to blend the gases in the desired amounts
An audible alarm
-that functions to alert the user to a drop in source pressure of either gas
85
Types of oxygen conservation devices
Oxymatic
Oxymizer Pendant
Puritan Bennett CR 50
DeVilbiss
86
Oxygen Conservation Devices
Devices to make the tank last longer
2 ways to maximize the contents of the tank:
-Add reservoir - can lower the flow on the tank
-Pulse Dosing - deliver oxygen when they breathe in and not when they exhale
87
Fixed Pressure/Multiple Orifice
Barrel Reg
-Pin Index Safety System
88
How is back pressure generated? What affect does back pressure have on the devices?
When a gas flow encounters a restriction, back pressure is generated.
Back pressure can alter the litre flow and calibration of the equipment being used it is high enough
89
What are 3 things that can affect Thorpe tubes?
Position of the flow meter
-A kinetic device must be in an upright position
Back pressure compensation
-one where indicated flow is the same as actual flow even in the face of back pressure
Condition of the flow tube
-A dirty, damaged, or wet tube will restrict movement of the ball float
90
Variable Orifice/Fixed Pressure
Thorpe Tubes
-A vertical tube gradually increasing in diameter
Two opposing forces
-Gravity acting on the float pulling it downward against the force of the gas flow
-Force of molecules striking the float and causing it to rise
As gas flows up, the float is forced higher into the Thorpe tube allowing more gas to flow around it, through annular space.
When the two forces reach an equilibrium, the float will be stationary.
91
Venturi Mask
Consists of a jet nozzle, entrainment ports, and a mask
The amount of entrainment depends on:
-Flow rate of the source gas entering the nozzle
-Size of jet nozzle (fixed or interchangeable)
-Size of entrainment ports (fixed or variable)
The higher the velocity of source gas, the higher possible entrainment
Total flow must be higher than patient's inspiratory demand to ensure no dilution around mask.
Although Pitot type devices can handle some back pressure, all entrainment devices lose accuracy in the face of significant downstream back pressure
-if condensation builds up on the corrugated tubing, the back pressure will decrease the total flow, FiO2 will increase
Can be set to fixed performance
-Only at a low FiO2 (<0.35)
92
What is another way to ensure patient's FiO2 needs are being met other than inspiratory flow?
Inspiratory Volume
Reservoirs (all the below can guarantee a known FiO2)
-Anesthesia Circuits
-Infant isolette
-Oxyhood
93
T-Piece (literal T shaped tube)
-Reservoir addition to an open circuit
-Mist coming out the reservoir at end inhalation suggests adequate flow
-Some oxygen that is left in thee reservoir tubing that they didn't breathe in will be available for the next breath they take
Delivers desired FiO2 for tracheostomy, laryngectomy, ET tubes
94
How and when is a HFCN used?
Fixed device at high FiO2 and high flow
-Run at flush (40LPM)
-Start FiO2 at minimum 0.60
SpO2 < 86%
Need a high FiO2
Indications for humidity
95
High Volume Nebulizer (HVN)
Can be heated or non heated
-HFCN (MistyOx), HHHHN (Optiflow)
Temperature control can be maintained with either a 'hot plate' or an immersion heater
-Desirable if the patient's normal airway has been bypassed
-Cold neb would be better in decreasing swelling or inflammation in the upper airway
Humidity deficit: @BTPS 43.8mg/L of water is needed to provide the patient sufficient humidity
The connector exiting the neb is a 22mm aerosol tubing connector to allow 2 to 4 meters of large bore tubing to be connected
-More tubing without a heating wire will lead to unacceptable condensation (or rain out) occurring If tubing is full of water and sitting in the corrugated tubing, get rid of it by disconnecting the tubing and disposing
-If it gets in the neb, the neb is contaminated
Patient apparatus can be: Aerosol Mask (intact airway) Face tent (intact airway) Trach cradle (bypassed airway; trach tube, stoma) T-Piece (bypassed airway; trach tube, E tube)
96
How and when is a LVN used?
Run at 10LPM
Start FiO2 at 0.30
-can only be fixed FiO2 at <35%
SpO2 ≥ 86%
Don't need high amounts of oxygen
Indications for humidity
97
Large Volume Nebulizer (LVN) (orange one)
Very precise FiO2 available by varying the port size
-FiO2s from 0.21 to 0.95 achievable
Minimum O2 Flow = 10LPM
-If you increase the flow, it won't reach fixed performance at high FiO2s
Minimum total flow should be 3-6x patient's resting demand or at least 60LPM to handle peaks
Large bore aerosol tubing (22mm) patient connections allows for humidity (mist) to be delivered
Often used with aerosol mask, T-piece, trach collar (cradle), face tent, etc.
