RC20 Chpater 38
What factors determine air to oxygen ratio
...
FiO₂ greater than ____ presents a significant risk of absorption atelectasis
0.50
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
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
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
what is the air to oxygen ratio of 60% oxygen?
1:1
What is the recommended maximum dose of nitric oxide
20ppm
What is the range of FiO₂ for oxygen tent
40 to 50
In large tents oxygen input flow od 12 to 15 L/min can provide only __________% oxygen levels
40 to 50%
Limit patient exposure to 100% oxygen to less than ____________ hours
24
Most AEMs can be set to deliver no more than ______ % oxygen
50
If a patient is on 3 L/min of oxygen, How much FiO₂ is the patient receiving
33%
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
what is the air to oxygen ratio for 40% oxygen?
3:1
If a patient is on 5 L/min of oxygen, How much FiO₂ is the patient receiving
41%
The total output flow of an air entrainment nebulizer set to deliver 40% oxygen ranges from
48 to 60 L/min
High FiO₂ is acceptable if the concentration can be decreased to 70% with in 2 days and 50% or less in ______ days
5
What is the minimum flow setting for a mask
5 L/min
What is the minimum for low that a high flow oxygen device must be set up
60 L/min
what is the minimum flowrate that high flow systems should be capable of delivering?
60 L/min
What is the minimum flow that should be set to prevent accumulation of CO2 in hoods
7 L/min
Hyperbaric therapy at three add-ons how much dissolved oxygen is in the plasma
7 mL/dL
Modern disposable non rebreathing mask normally do not provide much more than approximately _____ % oxygen
70
approximate FiO2 achieved with nonrebreathing mask
70+%
How often should you recheck a patient that has had an acute myocardial infarction
72 hours
1 atmosphere =
760 mm Hg or 101.32 KPa
Low flow oxygen systems provide supplemental oxygen directly to the airway at the flow of
8 mL/ min or less
FiO₂ 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
The American Academy of pediatrics recommends keeping arterial PO₂ in an infant less than _____ mm Hg as the best way to minimize the risk of ROP
80 mm Hg
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 concentration should He/O2 be?
80/20 or 70/30
What SpO₂ must a patient have in order to be discontinued from oxygen
92%
When is it a humidifier used
When the input flow is greater than 4 mL/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
Physiologic Responses of Healthy Individuals to exposure to 100% inspired oxygen 30 to 72 hours
Decreasing diffusing capacity
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 flow device should provide at least 60 L/min total flow There are two major categories of high flow devices: -Air Entrainment Systems -Blending Systems
Physiologic Responses of Healthy Individuals to exposure to 100% inspired oxygen 25 to 30 hours
Decreasing lung compliance Decreasing exercise PO₂
Physiologic Responses of Healthy Individuals to exposure to 100% inspired oxygen 12 to 24 hours
Decreasing vital lung capacity
Erin entrainment system
Direct the high-pressure oxygen source through a small nozzle or jet surrounded by air entrainment ports
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 to increase FiO₂ 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 system
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 SaO₂ of 85% to 90% with PaO₂ of 50 to 70 mm Hg
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 inability to produce high FiO2's tents are used primarily to provide pediatric aerosol therapy to children with croup or cystic fibrosis
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 will inhale room air and the delivered oxygen concentration may actually be lower than what is being delivered.
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
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 FiO₂ and total flow output
What are some issues with an oxyhood
CO₂ build up Loud Loss of heat difficult to clean or disinfect
Exposure to high PO₂ first damages the
Capillary endothelium, then interstitial edema follows
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
For patients with chronic hypoxemia, this increased workload over the long-term can lead to right ventricular failure which is known as
Cor pulmonale
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
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 entrainment port
what are the advantages of a nasal cannula
Easy to use on adult children and infants Disposable Low-cost Well-tolerated
How often should you recheck a patient using an oxygen hood
Every hour
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
What is the main problem with oxygen tents
Frequent opening and closing of the canopy causes wide swings in oxygen concentration
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
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 rebreathing of air At flows between 6 - 10 L/min FiO2's are between 35 - 60 %
Is an oxyhood considered a low flow or high flow oxygen delivery system
High flow
What type of low flow device can operate as a high flow FiO₂ device
High flow nasal canula, which creates an increase in airway pressure
Blending system
Separate pressurized air and oxygen sources are input, and the gases are mixed either manually or with the precision valve
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
Common problems with low flow oxygen delivery systems
In accurate flow System leaks or obstructions Device displacement Skin irritation
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 back pressure
Nitric oxide
Is a colorless odorless highly diffusible and lipid soluble free radical that oxidizes quickly to nitrogen dioxide in the presence of oxygen
Hyperbaric oxygen therapy
Is a therapeutic use of oxygen at pressures greater than one atmosphere
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
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 happens when the Venti mask ports are partially occluded
Less air is entrained Decrease total flow Increase oxygen
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 prevent entrainment of room air In concept a leak-free mask with competent valves and adequate flow should deliver 100% source gas. A truly fixed performance situation is difficult to achieve, however the nonrebreather mask will provide the highest FiO2 of the reservoir mask, with FiO2 around 70+%
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 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 are the three basic designs of oxygen delivery system
Low Flow Systems Reservoir systems High Flow Systems
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, FiO₂ frequently needs to be initially increased then slowly reduce to baseline over one or two hours
What are some disadvantages of an oxygen mask
Must be removed for eating Uncomfortable Aspiration hazard
When does a high flow system yield a set FiO₂
Must exceed patients flow demands and less then or equal to 35%
Low flow oxygen delivery systems include
Nasal cannula Nasal catheter Trans tracheal catheter
Which mask gives 60% FiO₂
Nombre breather
Physiologic Responses of Healthy Individuals to exposure to 100% inspired oxygen 0 to 12 hours
Normal pulmonary function Tracheo bronchitis Sub sternal chest pain
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 = 38 L/min So 22L of O2 and 38L of air should be blended together
the 4 major harmful effects of oxygen therapy
O2 toxicity, depression of ventilation, retinopathy of prematurity, absorption atelectasis
All oxygen delivery systems should be checked at least
Once per day
How much FiO₂ varies depends on
Oxygen input flow The mask volume The extent of air leakage Patient's breathing pattern
What are the indications for oxygen therapy
PaO₂ less than 60 mm Hg SpO₂ less than 90% Acute care situations in which hypoxemia is suspected Severe trauma Myocardial infarction Short-term therapy or surgical intervention post anesthesia recovery
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
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 air leaks. Consist of the reservoir cannula and reservoir masks.
The effects of inhailed nitric oxide are limited to the
Pulmonary circulation
Oxygen therapy can reverse
Pulmonary vasoconstriction Decrease right ventricular workload
What does hypoxemia cause
Pulmonary vasoconstriction Pulmonary hypertension
What are some examples of reservoir systems
Reservoir cannulas Masks Non-rebreathing circuit
What are the clinical signs of mild to moderate hypoxemia in the nervous system
Restlessness Disorientation Headaches
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
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
Three types of the reservoir masks
Simple mask Partial rebreathing mask Non-rebreathing mask
When a patient is breathing 100% oxygen, what is the earliest response
Sub sternal chest pain
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 severe hypoxemia in the respiratory system
Tachypnea Dyspnea Cyanosis
What are the clinical signs of mild to moderate hypoxemia in the respiratory system
Tachypnea Dyspnea Paleness
Nitric oxide has been approved for the treatment of
Term and near term neonates with hypoxic respiratory failure with associated pulmonary hypertension.
FiO₂ 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 should you do if the patient is on a non-re breather and the bag completely deflates
The flow is inadequate, increase the flow
Oxygen toxicity primarily affects what
The lungs and the central Nervous system
The larger the intake ports and the higher the gas velocity at the jet
The more air is entrained
the toxicity of oxygen is caused by
The overproduction of oxygen free radicals
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 determines the air to oxygen ratio and the delivered FiO₂
The size of the jet and entrainment ports
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
Oxyhood requires an AEN with tubing and a heater so
To no cause loss of heat to the infant
True of False High flow systems deliver oxygen and 100% or less
True
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 FiO₂ is lower
What are the early signs of in pending CNS toxicity
Twitching Sweating Pallor Restlessness
When is hyperbaric oxygen therapy used
Two most common air embolism carbon monoxide poisoning
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
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
A simple mask does not have
Valves Reservoir bag High FiO₂
When oxygen therapy is given is should decrease what
Work of breathing
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 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 minimum flow of 7 L/min should be set in order to prevent accumulation of carbon dioxide
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 there is no gas flow felt coming from the cannula
cause = flow meter not on or system leak procedure = adjust flow meter, check connections
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 5 L/min to prevent rebreathing of CO2, FiO2 35-50%, chosen when moderate FiO2 are needed for a short time
Low temperatures or convection cooling produced by high flow devices over the head can cause
heat lost and cold stress
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 inhalation
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
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)
define cor pulmonale
enlargement of the right ventricle of the heart due to disease of the lungs or of the pulmonary blood vessels
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
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 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
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)
What 2 factors affect the amount of air entrained?
jet size or orifice and the air entrainment port size
The oxygen provided by low flow device is always diluted with air, the result is a
low and variable FiO₂
What delivery system should be used with heliox
non re breather mask
how should heliox be delivered?
non-rebreather or simple mask
at what point is humidification needed for nasal cannula?
over 4 L/min
In premature infants cold stress can increase
oxygen consumption apena
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
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)
The primary types of oxygen in closers used for infants and children are
tents Incubators hoods
if the patient is constantly removing mask....
the causes can be claustrophobia (use alternative device) or confusion (use restraints)
if the reservoir bag collapses when the patient inhales...
the flow is inadequate so increase the flow
In emergencies and which tissue hypoxia is suspected patient should be given
the highest FiO₂ possible, ideally 100% Clinical examples include respiratory or cardiac arrest, severe trauma, shock, carbon monoxide poisoning, and cyanide poisoning
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 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
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)
What is the overall goal of oxygen therapy
to maintain adequate tissue oxygenation while minimizing cardiopulmonary work
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
