Ch.1 Oxygen and Medical Gas Therapy (Test 2) Flashcards
A pt is receiving O2 from an E cyclinder at 4 L/min through a nasal cannula. The cylinder pressure is 1900 psi . How long will cylinder run until it is empty?
A. 47 min
B. 1.7 h
C. 2.2 h
D. 3.6 h
2.2 h
After the RT sets up a nonrebreathing mask on a pt at a flow of 10 L/min, the reservoir bag collapses before the pt finishes inspiring. The RT should do which of the following?
A. Change to a simple O2 mask at a flow of 10 L/min
B. Remove the one-way valve from the exhalation port.
C. Place the pt on CPAP
D. Increase the flow to 15 L/min
Increase the flow to 15 L/min
The reservoir bag on a partial or nonrebreathing mask should remain one-third to one-half full at all times. If the bag contains less gas, then it is an indication of inadequate flow to the mask, and the flow from the flowmeter must be increased. Typically, flows of 10 to 15 L/min are necessary to maintain adequate flow.
A patient with carbon monoxide (CO) poisoning can best be treated with which of the following therapies?
A. Nasal cannula at 6 L/min
B. Simple O2 mask at 10 L/min
C. CPAP and 60% O2
D. Nonrebreathing mask
Nonrebreathing mask
Hemoglobin (Hb) has a greater affinity for carbon monoxide (CO) than it does for O2, but its affinity decreases as the O2 level in the blood increases. Therefore the higher the PaO2, the less affinity Hb has for CO, and O2 is then able to combine with Hb. A nonrebreathing mask provides the highest level of O2 of the four choices. It is important to provide the highest percentage of O2 available.
The following blood gas levels have been obtained from a patient using a 60% aerosol mask.
pH 7.47
PaCO2 31 mm Hg
PaO2 58 mm Hg
What should the respiratory therapist recommend at this time?
A. Place the patient on CPAP.
B. Increase the O2 to 70%.
C. Intubate and place the patient on mechanical ventilation.
D. Change to a nonrebreathing mask.
Place the patient on CPAP.
Hyperventilation with a PaO2 of only 58 mm Hg while receiving 60% O2 indicates intrapulmonary shunting with refractory hypoxemia. Intrapulmonary shunting is caused by atelectasis, pulmonary edema, or consolidated alveoli, none of which will improve by a simple increase in the O2 level. If the alveoli are collapsed or full of fluid or consolidated material, O2 will not be able to enter these alveoli and diffuse into the blood, and no matter how high the O2 level is increased, the PaO2 will not increase significantly. To deliver more O2 into the alveoli, apply pressure to increase the surface area for gas exchange to take place. This is accomplished with CPAP. In almost all cases on the exam, if the patient in the question is hyperventilating in response to hypoxemia with 60% O2 or higher, do not increase the FiO2. Apply CPAP
The respiratory therapist receives an order to set up a moderate level of O2 on a patient who arrives in the ED breathing at a rate of 35 breaths/min. Which of the following O2 delivery devices is most appropriate to use in this situation?
A. Simple O2 mask at 10 L/min
B. Nasal cannula at 4 L/min
C. Nonrebreathing mask at 15 L/min
D. Air-entrainment mask at 40% O2
Air-entrainment mask at 40% O2
Choices A, B, and C are all considered low-flow O2 devices. If a patient has a respiratory rate of more than 25/min or an inconsistent VT, high-flow devices such as the air-entrainment mask are recommended. A moderate level of O2 is a range of 40% to 60%.
A severe COPD patient arrives in the emergency department on a 2 L/min nasal cannula. Arterial blood gas results follow:
pH 7.32
PaCO2 67 mm Hg
PaO2 62 mm Hg
HCO3 38 mEq/L
Which of the following is the most appropriate recommendation?
A. Increase the liter flow to 4 L/min.
B. Maintain the current O2 level.
C. Institute noninvasive positive pressure ventilation (NPPV).
D. Place on a nonrebreathing mask at 12 L/min.
Maintain the current O2 level.
These ABG results represent normal values for a severe COPD patient. Although the PaCO2 level is increased, provided the pH is 7.30 or higher, the patient is ventilating adequately; therefore noninvasive ventilation is not indicated. Keeping the PaO2 in the 50 to 65 mm Hg range is acceptable for a patient with chronic hypoxemia. Increasing the O2 level and thereby increasing the PaO2 above 70 mm Hg increases the possibility of reducing the patient’s drive to breathe.
The physician has ordered O2 to be set up on a patient who has a spontaneous tidal volume of 500 mL and an inspiratory time of 1 second. Which of the following O2 delivery devices will deliver a flow that meets or exceeds this patient’s inspiratory flow?
A. 35% air-entrainment mask at 6 L/min
B. 60% aerosol mask at 12 L/min
C. Nonrebreathing mask at 15 L/min
D. Simple O2 mask at 10 L/min
35% air-entrainment mask at 6 L/min
A patient breathing 50% oxygen has a PaO2 of
248 torr. Which of the following should the respiratory therapist recommend?
A. Discontinue oxygen therapy.
B. Decrease the oxygen to 30%.
C. Titrate oxygen to maintain an SpO2 .93%.
D. Repeat the blood gases because the PaO2 is not
possible on this FiO2.
Titrate oxygen to maintain an SpO2 .93%
A PaO2 of approximately 250 torr is normal on 50% oxygen. Titrating the oxygen level is indicated. Remember, to determine the normal PaO2 on any given O2%, multiply the O2% by 5. This is an approximation. If titrate was not a choice, then discontinue oxygen.
A patient is receiving 30% oxygen via an air- entrainment mask at a flow of 5 L/min. The total flow delivered by this device is which of the following?
A. 36 L/min
B. 45 L/min
C. 54 L/min
D. 60 L/min
45 L/min
To calculate the total flow delivered by a high-flow O2 delivery device, the sum of the air/O2 ratio parts for the O2 percentage of the device is multiplied by the flow from the flowmeter supplying the device. The air/ O2 ratio for 30% is 8:1. In other words, for every 1 L of O2 flow from the flowmeter, 8 L of air is being en- trained into the device. Add the ratio parts together, 8 +1= 9, and then multiply by the liter flow of 5 L/min: 9 x 5 = 45 L/min.
Cylinders are constructed of chrome
molybdenum steel.
know
Gas cylinders are stored at high pressures; a
full O2 cylinder contains _______ psig pressure.
2200
O2 tank color
green
helium
brown
carbon dioxide
gray
nitous oxide
light blue
cyclopropane
orange
ethylene
red
air
yellow
co2/o2
gray and green
Heliox
Brown and green
Indications for O2 Therapy (3)
- Hypoxemia
- Labored breathing or dyspnea
- Increased myocardial work
Signs and Symptoms of Hypoxemia (7)
- Tachycardia
- Dyspnea
- Cyanosis (unless anemia is present)
- Impairment of special senses
- Headache
- Mental disturbance
- Slight hyperventilation
To determine what a normal PaO2 is while any oxygen percentage is being breathed, multiply the percentage by 5. For example, a normal PaO2 for a patient breathing 40% oxygen would be approximately 200 torr
(40 x 5) This is an approximation but can be helpful on the exam. If a patient on 40% has a PaO2 of 300 torr, this represents a laboratory error because it’s not possible to have a PaO2 that high on 40%. If the PaO2 is approximately five times the O2% that the patient is breathing, titrate the oxygen level or discontinue the oxygen if titration is not a choice.
KNOW
Complications of O2 Therapy (5)
- Respiratory depression
- Atelectasis
- O2 toxicity
- Reduced mucociliary activity
- Retinopathy of prematurity (ROP)
What are the 4 types of hypoxia?
- Hypoxemic hypoxia
- Anemic hypoxia
- Stagnant (circulatory) hypoxia
- Histotoxic hypoxia
Hypoxemic hypoxia
Is caused by lack of O2 in the blood as a result of:
1. Inadequate O2 in the inspired air
2. Alveolar hypoventilation
3. V/q mismatch
If the flowmeter is turned off completely but gas is still bubbling through the humidifier or is heard coming from the flowmeter, the valve seat is faulty and the flowmeter should be replaced **
Know
The advantage of the Bourdon gauge is that, unlike Thorpe tube flowmeters, it is not position dependent. It reads just as accurately in a horizontal position as it
does in a vertical position. This makes it the flowmeter of choice when transporting a patient with an oxygen tank. **
Know
Reduced mucociliary activity: Maintain FiO2
below 60%
If a normal PaO2 level cannot be maintained with a 60% O2 mask, a large shunt is probable and should not be treated with higher O2 concentrations. What shoud be adminstristered?
CPAP
Remember if a pt is breathing over 25 breaths per min do not use a low flow breathing o2 device. Instead use an
Air entrainment mask for high flow delivery
A blender consists of pressure-regulating valves that regulate O2 and air inlet pressure, a mixture control (precision metering device), and an audible alarm system that sounds if there is a drop in inlet pressure.
When using a blender/nebulizer to provide O2, make sure the nebulizer
set on 100%
Alveolar Air equation
Pb-ph20 x FiO2 - PaCO2 x 1.25
Heliox- Helium does not support life and therefore must be mixed with O2.
Know
Two common mixtures are:
a. 80% helium and 20% O2
b. 70% helium and 30% O2
Heliox mixtures are safe and may be of benefit in the treatment of:
a. Obstruction from secretions
b. Asthma (during episodes of bronchospasm)
c. Airway obstructions (tumors, foreign bodies, tracheomalacia)
For an 80:20 mixture of helium and O2, multiply the flowmeter reading by 1.8 to determine the correct flow rate.
To deliver aspecific flow, divide the flow rate by 1.8.
Example:
An 80:20 heliox mixture is running through an O2 flowmeter at 10 L/min. What is the ACTUAL flow rate?
10 x 1.8 = 18L min
EXAMPLE FOR HELIOX
You want to deliver 12 L/min of an 80:20 heliox mixture to the patient. What must you set the O2 flowmeter on to deliver this flow rate?
12/ 1.8 = 6.6 L min
For a 70:30 mixture of heliox, multiply the flowmeter reading by 1.6.
Divide by 1.6 to obtain a specific flow rate.
KNOW
Nitric Oxide
Inhaled nitric oxide (NO) is a selective pulmonary vasodilator that improves blood flow to ventilated alveoli, which results in decreased intrapulmonary shunting and improved arterial oxygenation.
When is Nitric Oxide indictaed?
It is indicated in term or near-term neonates of more than 34 weeks’ gestation who have evidence of persistent pulmonary hypertension of the newborn (PPHN).
Which electrode calculates pcO2
Severinghaus
This is composed of a platinum cathode and silver anode, and measures PO2
Clark electrode
In order to achieve accurate ptO2 the skin probe temperature must be __ which may lead to burning of the skin
44 c
PtcO2 is reliable with skin temperature even as low as
37 c
TC monitoring time
8-12 hours
Changing sites as often as every 2 hours may be necessary in small premature neonatal to avoid thermal injury
KNOW
Examples of O2 analyzers
- Galvanic cell o2
- Polarographic O2 analyzer
How is the galvanic cell used?
Electrolyte gel is used to chemically reduce O2 to electron flow
How is the polarographic O2 used?
A battery polarizes the electrodes to allow O2 reduction to occur, which gives off electron flow
For both the galvanic and polarographic the Clark electrode is used to measure O2 concentration
KNOW
Troubleshooting galvanic
Check gel
Troubleshooting polarographic
Check battery
Indications of hyperbaric o2 therapy (6)
- CO poisoning
- Cyanide poisoning
- Decompressing sickness (“the bends”)
- Gas gangrene
- Gas embolism
- Osteonecrosis
Causes of inaccurate reading on pulse ox
- low blood perfusion
- co poisoning
- severe asthma
- hypotension
- hypothermia
- cardiac arrest
- nail polish (especially blue, green, brown, and black)
- ambient light sources
- dark skin
Hemoximetry
