Ch. 38 Medical Gas Therapy
When should a humidifier be used with a nasal cannula and why?
When input flow is greater than 4L/min. Flows greater than 6-8L/min can cause nasal dryness, discomfort, and bleeding.
Under what circumstances does air dilution occur and FiO2 becomes variable?
When the flow output from the air entrainment device decreases to less than the patient's inspiratory flow.
How often should a reservoir cannula be replace? a. every 3 weeks b. every day c.every week d. every 2 hours
a. every 3 weeks
In the exudative phase what happens due to the alveolar fluid build up?
it leads to low ventilation/perfusion ratio, physiologic shunting and hypoxemia.
What would happen of the new vessels that formed began to hemorrhage?
it would cause scarring behind the retina that would lead to retinal detachment and blindness.
What is the primary reason that some COPD patients hyperventilate?
the suppression of hypoxic drive.
What are free radicals and how are they involved with oxygen toxicity:?
they are the by-products of cellular metabolism and toxicity is the result of the over production of O2 free radicals.
What is the overall goal of using Oxygen therapy?
to maintain adequate tissue oxygenation
PaO2 greater than or equal to 60 mm Hg is a precaution for use of oxygen therapy according to AARC guidlines, true or false?
true
True or false? Supplemental oxygen should never be withheld from hypoxic patients?
true
A system that supplies only a part of the inspired gas is what type of FiO2 systems?
variable
Explain what happens if lung collapsed occured due to obstruction of the alveolar region?
The O2 rapidly diffuses in to the blood and because the gas pressure decreases in the alveoli, it collapses.
Explain what happens when a person breaths in high levels of Oxygen.
The body's nitrogen levels deplete and the total pressure of venous gases decrease. Gases that exist rapidly diffuse into the venous blood.
Compare a disposable non rebreather to a leak free non rebreather.
The disposable non rebreathers only provide about 70% oxygen and the leak free non rebreathers can provide 100%
True or false, nasal catheters can be used on neonates.
False
What are the other AARC indications?
-Acute care in which hypoxemia is suspected -Severe trauma -Acute myocardial infarction (MI) -Short-term therapy or surgical intervention
What are the indications, according to the AARC, for oxygen therapy use for hypoxemia?
-PaO2 less than 60 mm Hg or SaO2 less than 90 % in subjects breathing room air -PaO2 or Sao2 below desirable range for a specific clinical situation
There are two key questions the user must answer to decide the performance of an O2 device, what are they?
1. How much oxygen can the system deliver? 2. Does the delivered FiO2 remained fixed or does it vary depending on the patients demands?
What is the flow rate for newborns and infants?
2L/min.
What is the input flow for an adult using a simple mask? Why?
5-10 L/min. Because if the patient needs more than 10 L/min, a high flow system should be considered, and if the patient needs less than 5L/min, the volume is dead space and causes carbon dioxide rebreathimg
At low flow, reservoir cannulas can reduce O2 use by how much?
50 - 75%
At what rate do most low-flow systems provide oxygen directly to the airway and why?
8L/min, because the inspiratory flow of an adult exceeds 8L/min, so the oxygen provided is diluted with air and results in a low and variable FiO2.
Which of the following are types of low flow systems? *Hint: more than one answer A. nasal cannula B. Venti Mask C. Nasal Catheter D. Non-rebreather E. Transtracheal catheter
A, C, E
Which of the following can cause contamination when used? A. Nasal Cannula B. Humidifiers C. Nebulizers D. Venti mask E. All of the above
B and C
Why should a nasal catheter be changed every 8 hours?
Because it can affect the production of secretions.
When a person is exposed to high PO2 for long periods of time, what might the symptoms be similar to?
Bronchopneumonia
How is a transtracheal catheteter inserted?
By a physician using a guidewire directly into the trachea between the 2nd and 3rd tracheal rings.
How is the need for oxygen therapy determined?
By the measurement of inadequate PaO2 or SaO2, or both.
If a person is exposed to 100 percent oxygen for 12-24 hours what would the physiologic response be?
Decreasing in vital capacity
True or false: Air entrainment devices always provide more than 100% oxygen
False ; they always provide LESS than 100%
True or false, a nasal cannula uses less oxygen than a transtracheal catheter.
False, transtracheal catheters use about 40-60% less than a nasal cannula.
True or false: For a low flow reservoir system to function correctly, patient must inhale through the nose.
False. Patient must EXHALE through the nose
True of false? Premature infants with a PaO2 greater than 90 mm Hg may contribute to retinopathy or prematurity is a precaution for use of oxygen therapy?
False. Premature infants with a PaO2 greater than 80 mm Hg, not 90.
The greateer the inspiratory flow, the more air is breathed and the FiO2 is higher. True or false
False: the FiO2 is lower
Explain what happens when someone is exposed to high FiO2.
First, it damages the capillary endothelium, then interstitial edema follows and thickens the alveolar-capillary membrane. resulting in the destruction of type 1 alveolar cells and the reproduction of type 2 cells.
What could you do to help clear trapped air in the abdomen or thorax?
Give patient high levels of oxygen
Increased atmospheric pressure often involves the adminstration of supplemental oxygen and greatly increases fire hazard involves what type of oxygen therapy?
Hyperbaric O2 therapy
Under what conditions is there a great risk for absorption atelectasis and what kind of patients are at a high risk?
If the FiO2 is greater than 0.50, there is a great risk for absorption atelectasis. And in patients that breath low tidal volumes because of sedation surgical pain or central nervous system dysfunction.
What does increased ventilatory demand do and how can oxygen therapy help?
Increased ventilatory demand increases the work of breathing. Oxygen therapy can reduce high ventilatory demand and work of breathing.
What can happen if oxygen flow is directed directly toward an infant's face?
It may stimulate and alteration is respiratory pattern.
AARC contraindications?
No specific contraindications when indications are present.
What are the objectives for giving Oxygen Therapy?
Objectives are correct documented or suspected acute hypoxemia, decrease symptoms associated with hypoxemia, and to decrease the workload on the cardiopulmonary system the hypoxemia imposes.
What type of situations would you avoid using a nasal catheter?
On patients with maxillofacial trauma, basal skull fratures, nasal obstruction, and coagulation problems. (blood clot formation)
When do air entrainment devices function as a true high flow system?
Only at low FiO2
Name some of the fire hazards involved in the clinical setting.
Operating room with some respiratory procedures. Procedures such as tracheotomies, electronic scalpels, and higher O2 concentrations under surgical drapes.
What happen with a transtracheal catheter during expiration?
Oxygen builds up in the trachea and upper airway and expands the anatomic reservoir which increases the FiO2.
What are some examples of disorders that are associated with hypoxemia?
Postoperative patients, patients with carbon monoxide or cyanide poisoning, shock, trauma, or acute myocardial infarction, and some premature babies.
What are the differences in a partial and non rebreather mask?
The partial non rebreather has no valves that separate the mask and the bag so the patient's exhaled gas also enters the bag. the non rebreather mask prevents this one way breathing with one-way valves.
What are the similarities between a partial and non rebreather masks?
They both have a 1L reservoir bag and provide higher FiO2 than the simple mask.
True or false, Cannulas should not be used in newborns or infants if nasal obstruction is present.
True
What provides enough oxygen and do you use a humidifier?
Tubing is connected to a flow meter that provides the oxygen and you do not have to use a humidifier because the flow is so low
What should the therapist use during a laser bronchoscopy or tracheostomy?
Use minimal amount of FiO2 to avoid intratracheal ignition.
With oxygen therapy when often should you monitor a patient and for what condition?
Within 12 hours with an FiO2 less than 0.40 or within 8 hours if FiO2 is 0.40 or greater
Is a high flow system fixed? Why or Why not?
Yes because the high flow systems exceeds patients flow and provides a fixed FiO2.
What type of system supplies oxygen concentration at a flow that equals or exceeds the patient's peak inspiratory flow?
a high flow system
What type of system can be used to achieve a fixed FiO2? and what must happen in order for it to be a fixed FiO2?
a reservoir system. It must always exceed the patients tidal volume and their cannot be any leaks
What factor determines how a device system is used? a. the clinical performance b. the type of device c. the patient d. the physician
a. the clinical performance ultimately decides how the device is used
Which of these are precautions for oxygen therapy use? a. FiO2 greater than 0.5 b. O2 toxicity c. depression of ciliary or leukocyte function d. absorption atelectasis e.all of the above?
all of the above
How much oxygen can a nasal reservoir cannula store?
approx 20 ml of O2
How often should O2 delivery systems be checked?
at least once per day
Which factor determines harmful effects of oxygen? a. high blood pressure b.PO2 and exposure time c. type of device used d. patient condition
b. po2 and exposure time
The following circumstances require you to check delivery systems more than once per day EXCEPT: a. equipment giving supplemental oxygen to newborns or preterm babies b. venti masks c. devices for artificial airways d. those susceptible to variation in FiO2 e.devices delivering a heated gas mix f. those who require and FiO2 greater than 0.50
b. venti masks
How does oxygen therapy correct hypoxemia?
by increasing alveolar and blood levels of oxygen
This type of device is designed to conserve oxygen. Is it? a. simple mask b. oxyhood c. reservoir cannula d.nasal catheter
c. reservoir cannula
The following antioxidants can defend against O2 free radicals except? a. vitamin e b.vitamin c c.vitamin d d. beta carotene
c. vitamin d.
The outcome of assessment is determined by what?
clinical and physiologic assessment to establish how the well the patient responds to therapy
What can occur with a low flow system if a patient's inspiratory flow exceeds the flow that is delivered by the device?
the result is air dilution.
Retinopathy of prematurity occurs at what age? a. 2 months b. 3 years c. 9 months d. 1 month
d. one month
Hypoxemia causes pulmonary vasoconstriction and hypertension, what does this do to the heart?
it increases the workload on the right side of the heart.
True or false? the goal should always be to use the highest possible FiO2 compatible with adequate tissue oxygenation?
false. it is to use the lowest possible FiO2.
High FiO2 increases what?
fire hazard
What type of system delivers more than 60% oxygen?
high-flow
Finish this sentence: The larger the intake port and the ________ the gas velocity, the more ____ is entrained.
higher; air
What happens at the end of the cycle in management of hypoxemia with high FiO2?
hyaline membranes form in the alveolar region and pulmonary fibrosis and hypertension develop.
What other factors are associated with ROP (Retinopathy of prematurity)?
hypercapnia, hypocapnia, intraventricular hemorrhage, infection, lactic acidosis, anemia, hypoclemia, and hypothermia.
What is the greatest problem with low flow flowmeters?
inaccurate flow
How does the cardiopulmonary system compensate for hypoxemia?
it increases ventilation and cardiac output.
How is high pressure O2 directed in an air entrainment system?
it is directed through a small nozzle or a jet that is surrounded by air entrainment ports
Finish this statement: In a nasal reservoir cannula, the amount of O2 available ________ with each breath and _______ the flow needed for a given FiO2.
increases; decreases
If a nasal catheter is placed too deep what is the result?
it can cause patient to gag or swallow gas which increases the chances of aspiration
What effects does oxygen toxicity have on the central nervous system and under what circumstances do these effects happen?
it can cause tremors, twitching, and convulsions and only occurs when a patient is breathing O2 at pressures greater than 1 atm (hyperbaric pressure)
What are the ways hypoxemia can manifest?
it can have manifestations of tachypnea, tachycardia, cyanosis, and distressed appearance.
What is the recommended arterial PO2 for an infant to minimize ROP?
less than 80 mm Hg
This system delivers less than 35% oxygen. What is it?
low-flow
What part of the body does oxygen toxicity affect?
lungs and central nervous system
What can be done to reduce the risk of fire hazards in the health care facility?
managing oxygen, heat, and fuel. Using the lowest effective FiO2. Also, avoiding the use of inappropriate or outdated equipment and patient,caregiver, and clinician education.
What type of system delivers oxygen at 35-60%?
moderate flow
What devices are a contraindication for oxygen therapy?
nasal cannulas, and nasopharyngeal catheters in pediatric and neonates with nasal obstruction.
In low birth weight infants or preterm babies, excessive blood O2 levels can cause retinal vasoconstriction, what does this lead to?
necrosis of the blood vessels. Which in turn causes new vessels to form and increase in number.
What type of patient would you assess within 1 hour of initial therapy?
neonate
Is humidification necessary with a reservoir systems?
no because it operates at a low flow
If O2 therapy causes a patient to hyperventilate, should the RT stop giving it to them?
no. hypoxia prevention is always first priority
How do patients with arterial hypoxemia maintain acceptable tissue oxygenation?
only by increasing cardiac output
What type of reservoir cannula is worn on the chest and can be hidden by the patient's clothing?
pendant reservoir
What is the most commonly used reservoir system?
reservoir mask
What are the fire hazards involved with in home care patients?
smoking while receiving low-flow oxygen and the use of aluminum oxygen regulators
What are some other problems associated with low-flow systems?
system leaks and obstructions, device displacement and skin irritations
What two components does the FiO2 depend on in an air entrainment mask?
the air to oxygen ratio and the amount of flow resistance downstream from the mixing site.
If a patient is diagnosed with COPD when would you monitor that patient?
within 2 hours of initial therapy
When should you monitor patients with acute myocardial infarction?
within 72 hours of initial therapy