What is the overall goal of oxygen therapy
to maintain adequate tissue oxygenation while minimizing cardiopulmonary work
the three specific clinical objectives for oxygen therapy
1) correct documented or suspected acute hypoxemia 2) decrease the symptoms associated with chronic hypoxemia 3) decrease the workload hypoxemia imposes on the cardiopulmonary system
define cor pulmonale
enlargement of the right ventricle of the heart due to disease of the lungs or of the pulmonary blood vessels
the 4 major harmful effects of oxygen therapy
O2 toxicity, depression of ventilation, retinopathy of prematurity, absorption atelectasis
basic characteristics of low-flow systems
supply O2 @ 8 L/ or less, don't meet pt's inspiratory flow needs so pt draws room air resulting in low & variable FiO2 (amount depends on pt's inspiratory flow rate, tidal volume, and the O2 flow delivered)
at what point is humidification needed for nasal cannula?
over 4 L/min
what is the most common liter flow and resultant FiO2s for nasal cannula
1-5 L/min, there is a 4% increase in FiO2 for every 1 L/min so the pt's FiO2 from room air is .21 and if @ 2 L/min, will be .21 + .08 = .29
basic characteristics of a transtracheal catheter
deliver O2 directly into the trachea through a small bore catheter that is surgically inserted into the trachea; uses 40-60% less O2 flow than cannula so no humidification necessary; O2 builds up in trachea during expiration & is taken in during inhalatio
what is the cause and procedure for when there is no gas flow felt coming from the cannula
cause = flow meter not on or system leak
procedure = adjust flow meter, check connections
what is the cause and procedure for when the humidifier pop-off is sounding
cause & procedure
obstruction distal to humidifier - find and correct obstruction
flow is set too high - use alternative device
obstructed naris - use alternative device
what is the cause and procedure for when pt reports soreness over lip or ears
irritation or inflammation caused by appliance straps - loosen straps or place cotton balls at pressure pints or use an alternative device
what is the cause and procedure for when the pt is mouth breathing
habitual mouth breathing or blocked nasal passages - switch to a simple or venturi mask
define reservoir systems
Provides a mechanism to gather and store oxygen between patient breaths.
Classified as a variable performance device, however can be a fixed performance device as long
as the stored volume equals or exceeds the patient's tidal volume and there are not any
characteristics of a simple mask
cover mouth and nose with the body of the mask gathering & storing O2 between pt breaths; exhaled air escapes through holes in its body. If O2 input is interrupted, air is drawn through these holes and around the mask edge. Flows of 5-12 L/min, minimum of
characteristics of partial rebreather mask
Has a 1 liter reservoir bag
which increases the reservoir volume therefore increases the FiO2 over a simple
mask
The bag is open to the flow
of exhalation gases and does allow the first portion of the exhaled gases to
enter the reservoir, thus the rebreat
characteristics of a nonrebreather mask
Like the partial rebreathing mask it has a 1
liter reservoir bag, however it also has a series of one-way valves.
A one way valve between the
bag and mask prevents exhaled gas from returning into the bag. One way valves
placed on the exhalation ports will
approximate FiO2 achieved with simple mask
35-50% @ 5-12 L/min
approximate FiO2 achieved with partial rebreathing mask
35-60% @ 6-10 L/min
approximate FiO2 achieved with nonrebreathing mask
70+%
if the patient is constantly removing mask....
the causes can be claustrophobia (use alternative device) or confusion (use restraints)
if no gas flow can be detected with the reservoir mask...
either the flowmeter is not on (so turn it on) or there is a system leak (check connections)
if the humidifier pop-off is sounding...
either there is an obstruction distal to the humidifier ( find and correct the obstruction), the input flow is too high ( omit humidifier if treatment is short term), or there is a jammed inspiratory valve ( fix or replace valve)
if the reservoir bag collapses when the patient inhales...
the flow is inadequate so increase the flow
if the reservoir bag remains inflated throughout inhalation...
there is either a large mask leak (correct leak) or the inspiratory valve is jammed or reversed (repair or replace the mask)
if erythema develops over face or ears...
irritation or inflammation due to appliance or straps (provide skin carem use an alternative device, or place cotton balls on affected areas to act as a buffer between the skin and equipment)
describe high flow systems
Also known as fixed performance devices
High flow systems supply a given oxygen concentration at a flow that equals or exceeds
the patients inspiratory flow, thus ensuring a stable FiO2
In order to meet variations in patient's inspiratory demands, a high
what is the minimum flowrate that high flow systems should be capable of delivering?
60 L/min
how do air entrainment systems operate
Directs a high-pressure oxygen source through a small nozzle or jet surrounded by air entrainment ports
As the oxygen flows through the restricted orifice the velocity increases.
The increased velocity pulls in or entrains room air through the air entrain
What 2 factors affect the amount of air entrained?
jet size or orifice and the air entrainment port size
what effect does the jet size have on the way the air entrainment system operates?
the smaller the jet the higher the velocity, the high the velocity the more air entrained so the lower the FiO2 and the greater the total output flow
what effect does the air entrainment port size have on the system?
the larger the air entrainment port the more air entrained so the lower the FiO2 and the greater the total output flow
What formula is used to calculate the air to oxygen ratio?
Liters of air divided by the liters of O2 = (100-%O2) / (%O2-21)
%O2 = [(Air flow x 21) + (O2 flow x 100)] / total flow
what is the air to oxygen ratio for 40% oxygen?
3:1
what is the air to oxygen ratio of 60% oxygen?
1:1
what is the effect of down stream flow resistance on air entrainment devices?
Any resistance to flow distal to the jet will result in less air entrained, therefore the delivered oxygen concentration will be increased.
However total flow will also be decreased, therefore if the total flow does not meet the patients needs the patient
how can extra humidification be added to the venturi mask:?
The best way to add humidification to a venturi
mask is to use an air entrainment nebulizer connected to the mask with the nebulizer connected to an air flowmeter
air entrainment mask vs air entrainment nebulizer
AEMs :
indicated for patients with
high or changing ventilatory demands needing a stable low - moderate FiO2
The most common problems
with AEM's are:
Providing sufficient total output flow to ensure a stable FiO2. Providing extra humidification
AENs:
Pneu
what are the two ways to assess adequacy of flow by an air entrainment nebulizer
A visual inspection to see if mist escapes from the T tube (in which case the pt's inspiratory flow needs are being met) and also to compare it to the pt's peak inspiratory flow (during tidal breathing is ~3x minute volume) and as long as it exceeds this
what are the 5 ways to achieve higher output flow for AENs
1) add open reservoir to expiratory side of T tube 2) provide inspiratory reservoir with one-way expiratory valve 3) connect 2+ nebulizers together in parallel 4) set nebulizer to low concentration; bleed-in oxygen; analyze, and adjust 5) use a commercial
when is it approriate to use a blender system?
when air-entrainment devices cannot provide a high enough O2 concentraion or flow and if the power goes out and the treatment cannot be administered without the power being on
How do you calculate the oxygen and air settings to achieve a specific FiO2 and flow rate when manually blending O2 and air?
O2 flow = [Total flow X (O2% - 21)] / 79
Air flow = Toal flow - O2 flow
Example:
to manually mix air and oxygen to provide a pt with 50% O2 at a total flow of 60 L/min.
O2 flow = (60x(50-21)) / 79
O2 flow = 22 L/min
Air flow = 60 L/min - 22 L/min
Air flow
what are the 3 types of oxygen enclosure devices?
hood, tent, incubator
what are the key features of an oxygen hood?
best method for controlled oxygen therapy to infants, covers only the head so the rest of the body is free to be cared for, Oxygen is delivered to the hood via either a heated air entrainment nebulizer of a blending system with a heated humidifier, and a
what are the key features of an oxygen tent?
Air conditioned or cooled by ice to provide a comfortable temperature within a plastic sheet canopy, Major problem is that frequent opening and closing of the canopy causes wide swings in oxygen concentration, and because of variability of FiO2 and inabil
what are the key features of an incubator?
high infection risk, completely enclose the pt, wide swings in O2 concentration due to the opening and closing of the unit to care for the pt.
nitric oxide therapeutic benefit
potent pulmonary vasodilator, by causing smooth muscle relaxation in the pulmonary capillary system. This improves blood flow to ventilated alveoli which helps reduce pulmonary vascular resistance
He's value as a therapeutic gas and the purpose?
based on the low density and is used to decrease the WoB in pts with large airway obstruction by decreasing the turbulence of flow in the airways which int urn requires a reduction in the driving pressure needed to move air flow past the obstruction
What concentration should He/O2 be?
80/20 or 70/30
how should heliox be delivered?
non-rebreather or simple mask
since an O2 flowmeter will be inaccurate when regulationg He flow, what conversion factor must be used to determine flowrate?
80/20 = 1.8
70/30 = 1.6
what are the common problems with He therapy?
ineffective for aerosol delivery, coughing less effectived b/c of reduced turbulent air flow, distorted speaking, and hypoxemia because of adding high levels of O2 decreased the effectiveness of the He
What are the three clinical objectives of oxygen therapy
Correct documented or suspected acute hypoxemia
Decrease symptoms associated with chronic hypoxemia
Decrease the workload hypoxemia imposes on the cardiopulmonary system
What does hypoxemia cause
Pulmonary vasoconstriction
Pulmonary hypertension
When oxygen therapy is given is should decrease what
Work of breathing
For patients with chronic hypoxemia, this increased workload over the long-term can lead to right ventricular failure which is known as
Cor pulmonale
Oxygen therapy can reverse
Pulmonary vasoconstriction
Decrease right ventricular workload
What are the three basic ways to determine whether a patient needs oxygen therapy
Use of laboratory Measures to document hypoxemia
A patients need for oxygen therapy can be based on the specific clinical problems or conditions
Hypoxemia has many manifestations, such as tachypnea tachycardia cyanosis and distressed overall appearance
What are the indications for oxygen therapy
PaO? less than 60 mm Hg
SpO? less than 90%
Acute care situations in which hypoxemia is suspected
Severe trauma
Myocardial infarction
Short-term therapy or surgical intervention post anesthesia recovery
How many hours must you recheck a patient with COPD
Every two hours
What are some possible complications of oxygen therapy
Fire hazard
Oxygen toxicity
Retinopathy of prematurity
All oxygen delivery systems should be checked at least
Once per day
How often should you recheck a patient that has had an acute myocardial infarction
72 hours
How often should you recheck a patient using an oxygen hood
Every hour
Is an oxyhood considered a low flow or high flow oxygen delivery system
High flow
Oxygen toxicity primarily affects what
The lungs and the central
Nervous system
Exposure to high PO? first damages the
Capillary endothelium, then interstitial edema follows
What are the clinical signs of mild to moderate hypoxemia in the respiratory system
Tachypnea
Dyspnea
Paleness
What are the clinical signs of severe hypoxemia in the respiratory system
Tachypnea
Dyspnea
Cyanosis
What are clinical signs of mild to moderate hypoxemia in the cardiovascular system
Tachycardia
Mild hypertension
Peripheral vasoconstriction
What are the clinical signs of severe hypoxemia in the cardiovascular system
Tachycardia, with eventual bradycardia, and arrhythmia
Hypertension and eventual hypotension
What are the clinical signs of mild to moderate hypoxemia in the nervous system
Restlessness
Disorientation
Headaches
What are the clinical signs of severe hypoxemia in the nervous system
Confusion
Distressed appearance
Blurred vision
Tunnel vision
Loss of coordination
In paired judgment
Slow reaction time
Manic-depressive activity
coma
Physiologic Responses of Healthy Individuals to exposure to 100% inspired oxygen 0 to 12 hours
Normal pulmonary function
Tracheo bronchitis
Sub sternal chest pain
Physiologic Responses of Healthy Individuals to exposure to 100% inspired oxygen 12 to 24 hours
Decreasing vital lung capacity
Physiologic Responses of Healthy Individuals to exposure to 100% inspired oxygen 25 to 30 hours
Decreasing lung compliance
Decreasing exercise PO?
Physiologic Responses of Healthy Individuals to exposure to 100% inspired oxygen 30 to 72 hours
Decreasing diffusing capacity
When a patient is breathing 100% oxygen, what is the earliest response
Sub sternal chest pain
Prolonged exposure to oxygen shows what on an x ray
Patchy infiltrates appear on chest radiographs and usually are most prominent in the lower lung fields
the toxicity of oxygen is caused by
The overproduction of oxygen free radicals
Limit patient exposure to 100% oxygen to less than ____________ hours
24
High FiO? is acceptable if the concentration can be decreased to 70% with in 2 days and 50% or less in ______ days
5
Retinopathy of prematurity
Is an abnormal either condition that occurs in some premature are low birth weight infants to receive supplemental oxygen. An excessive blood oxygen levels causes retinal vasoconstriction, which leads to necrosis of the blood vessel
The American Academy of pediatrics recommends keeping arterial PO? in an infant less than _____ mm Hg as the best way to minimize the risk of ROP
80 mm Hg
FiO? greater than ____ presents a significant risk of absorption atelectasis
0.50
The risk of absorption atelectasis is greatest in patient's breathing at low tidal volumes as a result of
Sedation
Surgical pain
Central nervous system dysfunction
How do you select the proper oxygen device
The selection of the proper oxygen device is based on its purpose the patient and it's performance
What are the three basic designs of oxygen delivery system
Low Flow Systems
Reservoir systems
High Flow Systems
The oxygen provided by low flow device is always diluted with air, the result is a
low and variable FiO?
Low flow oxygen delivery systems include
Nasal cannula
Nasal catheter
Trans tracheal catheter
Low flow oxygen systems provide supplemental oxygen directly to the airway at the flow of
8 mL/ min or less
what are the advantages of a nasal cannula
Easy to use on adult children and infants
Disposable
Low-cost
Well-tolerated
When is it a humidifier used
When the input flow is greater than 4 mL/min
If a patient is on 3 L/min of oxygen, How much FiO? is the patient receiving
33%
If a patient is on 5 L/min of oxygen, How much FiO? is the patient receiving
41%
Common problems with low flow oxygen delivery systems
In accurate flow
System leaks or obstructions
Device displacement
Skin irritation
What are some examples of reservoir systems
Reservoir cannulas
Masks
Non-rebreathing circuit
Three types of the reservoir masks
Simple mask
Partial rebreathing mask
Non-rebreathing mask
How much FiO? varies depends on
Oxygen input flow
The mask volume
The extent of air leakage
Patient's breathing pattern
What may cause the pop valve on the humidifier to make a squealing sound
It may be kinked
Obstruction distal to humidifier
Flow is set too high
Obstructed naris
What are some disadvantages of an oxygen mask
Must be removed for eating
Uncomfortable
Aspiration hazard
A simple mask does not have
Valves
Reservoir bag
High FiO?
What is the minimum flow setting for a mask
5 L/min
Which mask gives 60% FiO?
Nombre breather
What should you do if the patient is on a non-re breather and the bag completely deflates
The flow is inadequate, increase the flow
What is the minimum for low that a high flow oxygen device must be set up
60 L/min
True of False
High flow systems deliver oxygen and 100% or less
True
When does a high flow system yield a set FiO?
Must exceed patients flow demands and less then or equal to 35%
What factors determine air to oxygen ratio
...
What factors determine downstream resistance
In the presence of flow resistance distal to the Jets, the volume of air entrained always decreases. With less air being in trained, total flow output decreases, and the delivered oxygen concentration increases
Increase downstream flow resistance causes b
Modern disposable non rebreathing mask normally do not provide much more than approximately _____ % oxygen
70
Erin entrainment system
Direct the high-pressure oxygen source through a small nozzle or jet surrounded by air entrainment ports
The larger the intake ports and the higher the gas velocity at the jet
The more air is entrained
True or False
Because they dilute source oxygen with the air, entrainment devices always provide less than 100% oxygen
True
The more air they entrain, the higher is the total output flow, but the delivered FiO? is lower
What happens when the Venti mask ports are partially occluded
Less air is entrained
Decrease total flow
Increase oxygen
FiO? provided by air entrainment devices depends on two key variables
The air to oxygen ratio
The amount of flow resistance downstream from the mixing site
What determines the air to oxygen ratio and the delivered FiO?
The size of the jet and entrainment ports
If a patient is on 40% oxygen delivered thru an air entrainment nebulizer and the patient has a minute ventilation of 12 what is the minimum input flow that is required
10 L/min
How do you know if flow of 10 L per minute is enough for a patient
When the patient takes in a breath a little mist should still be in exhalation ports
Describe an oxygen blending system
Has 2 gas sources
Separate pressurized air and oxygen sources are input, and the gases are mixed either manually or with a precision valves
A physician orders that you manually mix gases. 45% oxygen with a flow of 60 L/min. How do you calculate?
Liter flow: 42%
LIters of oxygen: 18%
What is the range of FiO? for oxygen tent
40 to 50
Oxyhood requires an AEN with tubing and a heater so
To no cause loss of heat to the infant
What are some issues with an oxyhood
CO? build up
Loud
Loss of heat
difficult to clean or disinfect
What type of low flow device can operate as a high flow FiO? device
High flow nasal canula, which creates an increase in airway pressure
Why have air entrainment nebulizers been the traditional device of choice for delivering oxygen to patients with artificial tracheal airways
Because of added humidification and heat control
The total output flow of an air entrainment nebulizer set to deliver 40% oxygen ranges from
48 to 60 L/min
Most AEMs can be set to deliver no more than ______ % oxygen
50
How to increase FiO? of air entrainment nebulizers
Added open reservoir to expiratory side of T tube
Provide inspiratory reserve with one way expiratory valve
Connect to or more nebulizers together in parallel
Set nebulizer to low concentration bleed in oxygen analyze and adjust
Use a commercial door flow
Blending system
Separate pressurized air and oxygen sources are input, and the gases are mixed either manually or with the precision valve
What should be considered when an air entrainment devices cannot provide a high enough oxygen concentration or flow
Blending system, this system allows precise control over both FiO? and total flow output
The primary types of oxygen in closers used for infants and children are
tents
Incubators
hoods
What is the main problem with oxygen tents
Frequent opening and closing of the canopy causes wide swings in oxygen concentration
In large tents oxygen input flow od 12 to 15 L/min can provide only __________% oxygen levels
40 to 50%
What is the minimum flow that should be set to prevent accumulation of CO2 in hoods
7 L/min
Low temperatures or convection cooling produced by high flow devices over the head can cause
heat lost and cold stress
In premature infants cold stress can increase
oxygen consumption
apena
Patient factors in selecting oxygen therapy equipment
Severity and cause of hypoxemia
Patient age group
Degree of consciousness and alertness
Presence or absence of tracheal airway
Stability of minute ventilation
Mouth breathing versus a nose breathing patient
In emergencies and which tissue hypoxia is suspected patient should be given
the highest FiO? possible, ideally 100%
Clinical examples include respiratory or cardiac arrest, severe trauma, shock, carbon monoxide poisoning, and cyanide poisoning
A patient has acute on chronic episode. When is it safe to decrease oxygen or when are they considered stable
Adequate oxygenation of these patients generally means SaO? of 85% to 90% with PaO? of 50 to 70 mm Hg
A well-designed oxygen protocol ensures the patient
Undergoes initial assessment
Is evaluated for protocol criteria
Receives the treatment plan that is modified according to need
Stops receiving therapy as soon as it is no longer needed
Hyperbaric oxygen therapy
Is a therapeutic use of oxygen at pressures greater than one atmosphere
1 atmosphere =
760 mm Hg or 101.32 KPa
When is hyperbaric oxygen therapy used
Two most common
air embolism
carbon monoxide poisoning
What SpO? must a patient have in order to be discontinued from oxygen
92%
Hyperbaric therapy at three add-ons how much dissolved oxygen is in the plasma
7 mL/dL
FiO? at 100% what is the half life of carboxyhemoglobin
80 minutes
The half life of carboxyhemoglobin under hyperbaric oxygenation at 3 atm is only 23 minutes
What are the major complications of hyperbaric oxygen therapy
ear or sinus trauma
Tympanic membranes rupture
Alveolar over distention and pneumothorax
Gas embolism
CNS toxic reaction
Pulmonary toxic reaction
Fire
Sudden decompression
Reversible visual changes
Claustrophobia
Decreased cardiac
What are the early signs of in pending CNS toxicity
Twitching
Sweating
Pallor
Restlessness
Nitric oxide
Is a colorless odorless highly diffusible and lipid soluble free radical that oxidizes quickly to nitrogen dioxide in the presence of oxygen
What is the therapeutic benefit of inhaled nitric oxide
Improved bloodflow to ventilated alveoli
The result is a reduction in intrapulmonary shunting, improvement in arterial oxygenation, and a decrease in pulmonary vascular resistance and pulmonary arterial pressure
The effects of inhailed nitric oxide are limited to the
Pulmonary circulation
Nitric oxide has been approved for the treatment of
Term and near term neonates with hypoxic respiratory failure with associated pulmonary hypertension.
What is the recommended maximum dose of nitric oxide
20ppm
Toxic side effects of nitric oxide
Acute pulmonary edema
For or paradoxical respond
Methemoglobinemia
Increased left ventricular filling pressure
complications of certain cardiac anomalies
Rebound hypoxemia
Pulmonary hypertension
How do you prevent the rebound effect of nitric oxide
Make it oxide after used for more than a few hours should always be slowly weaned off over ours. When a nitric oxide is finally discontinued, FiO? frequently needs to be initially increased then slowly reduce to baseline over one or two hours
Why is Heliox use
To decrease the work of breathing
Heliox is less dense
Decrease the respiratory rate, the level of just Pineo, and the need for intubation and mechanical ventilation in patients with reversible obstructive disorders
What delivery system should be used with heliox
non re breather mask