Respiratory Care Exam Review

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A pt is receiving O2 from an E cylinder at 4 L/min through a NC. The cylinder pressure is 1900 psig. How long will the cylinder run until it is empty?

  1. 47 min
  2. 1.7 Hrs
  3. 2.2 hrs
  4. 3.6 hrs

1900 * 0.28 / 4 = 2.2

C 2.2 Hrs


After setting 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?

  1. Change to a simple O2 mask at a flow of 10 L/min
  2. Remove the one-way valve from the exhalation port
  3. Place the pt on continuous positive airway pressure (CPAP).
  4. Increase the flow to 15 L/min.

D Increase the flow to 15 L/min.


A pt with carbon monoxide (CO) poisioning can best be treated with which of the following therapies?

  1. NC @ 6 L/min
  2. Simple O2 mask @ 10 L/min.
  3. CPAP and 60% O2
  4. Nonrebreathing mask

D Nonrebreathing mask


The following ABG levels have been obtained from a pt using a 60% aerosol mask.

pH 7.47

PaCO2 31 mm Hg

PaO2 58 mm Hg

What should the RT recommend at this time?

  1. Place pt on CPAP
  2. Increase the O2 to 70%
  3. Intubate and place the pt on mechanical ventilation.
  4. Change to a nonrebreathing mask.

A Place the pt on CPAP


Given the following data, what is the pt's total arterial O2 content?

pH 7.41

PaCO2 37 mm Hg

PaO2 88 mm Hg

HCO3 26 mEq/L

SaO2 95%

Hb 14 g/dL

  1. 12 mL/dL
  2. 14 mL/dL
  3. 16 mL/dL
  4. 18 mL/dL

(1.34 * 14 * 0.95) + (88 * 0.003)

17.82 + 0.264

18.084 mL/dL

D 18 mL/dL


The RT receives an order to set up a moderate level of O2 on a pt 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?

  1. Simple O2 mask @ 10 L/min
  2. NC @ 4 L/min
  3. Nonrebreathing mask @ 15 L/min
  4. Air-entrainment mask @ 40% O2

D Air-entrainment mask @ 40% O2


A severe COPD pt arrives in the ED on a 2 L/min NC. ABG 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?

  1. Increase the liter of flow to 4 L/min
  2. Maintain the current O2 level.
  3. Institute noninvasive ventilation
  4. Place on a nonrebreathing mask @ 12 L/min

B Maintain the current O2 level.


The physician has ordered O2 to be set up on a pt who has a spontaneous Vt 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 pt's inspiratory flow?

  1. 35% air-entrainment mask @ 6 L/min
  2. 60% aerosol mask @ 12 L/min
  3. Nonrebreathing mask @ 15 L/min
  4. Simple O2 Mask @ 10 L/min.

0.5L / 1 sec = 0.5L/sec * 60 sec = 30 L/min (needed)

20 65

35 1:4.3 = 1:5 1+5=6 6 * 6= 36 L/min

100 15

A 35% air-entrainment mask @ 6 L/min


While making O2 rounds you discover the 6 inch reservoir tubing on a 60% T-piece set up has fallen off. What may result from this situation?

  1. the FiO2 could decrease
  2. The total flow to the pt could increase
  3. More room air entrainment could occur

1 & 3 only

FiO2 could decrease & More room air entrainment could occur


A pt is using a 30% air-entrainment mask at an O2 flow of 5 L/min. The total flow delivered by this device is which of the following?

  1. 36 L/min
  2. 45 L/min
  3. 54 L/min
  4. 60 L/min

20 65

35 8:1 8+1= 9 9 * 5= 45 L/min

100 15

B 45 L/min


How much does a H cylinder hold?

244 cu ft (6900 L) of O2


How much does a E cylinder hold?

22 cu ft (622 L) of O2


What safety system does the small cylinders use?

Pin Index Safety System (PISS)


What are the two types of safety relief devices on the cylinder?

  • Frangible disk- breaks at 3000 psig
  • Fusible plug- melts at 208 degree F

What is the color of a O2 cylinder?

Green; white


What is the color of a helium cylinder?



What is the color of a Carbon dioxide cylinder?



What is the color of a Nitrous oxide cylinder?

Light blue


What is the color of a cyclopropane cylinder?



What is the color of a Ethylene cylinder?



What is the color of a Air cylinder?



What is the color of a CO2/O2 cylinder?

Gray and green


What is the color of a He/O2 cylinder?

Brown and green


How often are the cylinders hydrostatically tested?

Every 5 to 10 years.


Hydrostatic testing determines what?

  • Wall stress
  • Cylinder expansion
  • Leaks

What is the purpose of having a regulator on the cylinder?

It reduces the pressure to a working pressure (50 psi)


What are the technical problems associated with reducing valves and regulators?

  • dust and debris entering the regulator (always crack it to blow anything out)
  • Constant pressure trapped in the pressure chamber after the cylinder is turned off may rupture the diaphragm.
  • A hold in the diaphragm will result in a continuous leak into the ambient chamber and out the vent hole, causing failure of the regulator.
  • A weak spring can result in diaphragm vibration and inadequate flows that are caused by premature closing of the inlet valve.
  • When attaching the regulator on E cylinder make sure the plastic washer is in place or gas will audibly leak around the cylinder valve outlet and regulator inlet.

How do you calculate an E cylinder for duration?

Cylinder pressure * 0.28 / flow rate


How do you calculate an H tank for duration?

Cylinder pressure * 3.14 / Flow rate


How do you calculate liquid O2?

Liquid (weight) * 860 / 2.5 L/Lbs = Liters

liters / flow rate = minutes left

minutes left / 60= tank duration


On a compensated flowmeter there are 3 ways to determine whether a flowmeter is compensated for pressure, what are they?

  • It is labeled as such on the flowmeter.
  • The needle valve is located after the float.
  • The float jumps when the flowmeter, while it is turned off, is plugged into a wall outlet.

What safety system does the flowmeter outlets use?

Diameter Index Safety System


What is wrong 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.


How is the bourdon gauge flowmeter calibrated?

In Liters/min


Is the bourdon gauge flowmeter compensated or uncompensated?



What happens when a humidifier or nebulizer is attached to the outlet of a bourdon gauge?

Back pressure is generated into the gauge (which measures pressure) and the gauge reading is higher than what the patient is actually receiving.


What is the advantage of the bourdon gauge flow meter?

It is not piston dependent. It reads just as accurately in a horizontal position as it does in a vertical position.


What happens when there's an obstruction to the flow through the tubing attached to the bourdon gauge?

The back pressure will cause the gauge reading to increase slightly. In other words, the gauge will indicate flow to the patient while the patient is receiving little or no oxygen.


What are the two types of air compressors that we generally use?

  • Piston air compressor
  • Diaphragm air compressor

What are the indications for oxygen therapy?

  • Hypoxemia
  • Labored breathing or dyspnea
  • Increased myocardial work

What are the signs and symptoms of hypoxemia?

  • Tachycardia
  • Dyspnea
  • Cyanosis (unless anemia is present)
  • Impairment of special senses
  • Headache
  • Mental disturbance
  • Slight hyperventilation

What are the complications of oxygen therapy?

  • Respiratory depression (patients with COPD who is chronically hypoxic is most affected. Maintain pao2 between 50 and 65 mmhg for these types of patients.)
  • Atelectasis (high oxygen concentrations in the lungs can wash out nitrogen in the lung and reduce the production of surfactant. Which may lead to atelectasis maintain fio2 below 60%.)
  • Oxygen toxicity (High oxygen concentrations results in increased oxygen free radicals and therefore lung tissue toxicity. This may lead to acute respiratory distress syndrome "ards". Maintain fio2 below 60%.)
  • Reduce mucociliary activity (maintain fio2 below 60%. The beating of the cilia in the mucociliary blanket is not as active when high fio2 levels are used)
  • Retinopathy of prematurity "ROP" (This is caused by high pao2 levels in infants and results in blindness. It is more common in premature infants. Maintain pao2 below 80 mmhg. The normal level of pao2 in infants is 50-70 mmhg.)

What is a normal pao2 value of a person less than 60 years old?

80 mm HG


What is a normal pao2 of a 70 year old?

70 mmhg


What is a normal pao2 of an 80 year old person?

60 mmhg


What are the four types of hypoxia?

  • Hypoxemic hypoxia
  • Anemic hypoxia
  • Stagnant circulatory hypoxia
  • Histotoxic hypoxia

When is it beneficial to administer oxygen therapy?

  • Inadequate oxygen in the inspired air
  • A ventilation perfusion mismatch

When is it not beneficial to administer oxygen therapy?

  • Alveolar hypoventilation
  • Diffusion defects (pulmonary edema, atelectasis and pulmonary fibrosis)
  • A anatomic right-to-left shunt

If a normal pao2 level cannot be maintained with a ___ oxygen mask, a large shunt is probable and should not be treated with higher oxygen concentrations.



When do you administer CPAP to a patient?

When the paco2 is at normal or below normal levels.


When is a patient declared needing mechanical ventilation?

Paco2 level is elevated in a patient with hypoxemia.


What is a normal hemoglobin level?

12 to 16 g/dL


How can the hemoglobin concent be increased?

By administering packed red blood cells.


What are the causes of anemic hypoxia?

  • Decreased hemoglobin
  • Carbon monoxide poisoning
  • Excessive blood loss
  • Methemoglobin
  • Iron deficiency

If a patient comes in and says that they have been exposed to carbon monoxide what do you do?

Give the patient 100% oxygen usually using a non rebreathing mask which delivers high oxygen concentrations.


What is another way that carbon monoxide poisoning can be treated other getting giving a non-rebreather?

Placing patient in a hyperbaric oxygen therapy chamber.


The level of carbon monoxide bound hemoglobin may be determined with what?

CO oximetry


How does a patient usually present with carbon monoxide poisoning when looking at an ABG?

A normal pao2 level with a low or normal paco2 level and the pH level is usually low as a result of lactic acidosis (metabolic acidosis) caused by severe hypoxia. lactic acid is produced as the body goes into an aerobic metabolism trying to provide more oxygen to the tissues


If a patient has a PaO2 of 255 mm Hg but saturation is at 60% do you need to turn their FiO2 down?

No, because thePaO2 is so high and their saturation is so low is because O2 is not able to combine to the Hb since it is already carrying CO therefore the O2 dissolves in the plasma there by increasing the PaO2 . The patient should not be titrated oxygen until their saturation is at 95% or greater.


How is excessive blood loss treated?

By administering blood to the patient.


What is the most common cause of methemoglobin?

nitrite poisoning


How is nitrite poisoning treated? causes increase in methemoglobin which can cause anemic hypoxia.

by administering ascorbic acid or methylene blue (by removing nitrite from the body)


How is iron deficiency treated?

increasing iron intake or by administering blood


What are the two ways blood carries oxygen?

  • Bound to Hb
  • Dissolved in plasma

How do you figure out the patients total arterial content?

(HB * 1.34 * SaO2) + (PaO2 * 0.003) = Total content


When a pt has stagnant hypoxia the O2 content and carrying capacity is normal but the capillary perfusion is diminished as a result of what?

  • Decreased HR
  • Decreased CO
  • Shock
  • Embolism

In histotoxic hypoxia the oxidative enzyme mechanism of the cell is impaired as a result of what?

  • Cyanide poisoning
  • Alcohol poisoning

In Histotoxic hypoxia is rarely accompanied by hypoxemia but is accompanied by ___________ venous PO2 levels.



What low flow device delivers 22-35% O2 at flows of 1/4 - 4 L/min, and this one is inserted into the trachea through the second and third tracheal rings.

Transtracheal catheter


What low flow device delivers 24-40% O2 at flow rates of 1/4 - 6 L/min?

Nasal cannula


What device delivers 22-35% O2 at flow rates of 1/4 to 4 L/min ?

Nasal Reservoir


What device delivers 35-50% O2 at flow rates of 5-10 L/min?

Simple O2 Mask


What device delivers 40-70% O2 at flow rates of 10-15 L/min?

Partial Rebreathing Mask


What device delivers 60-80% O2 at flow rates of 10-15 L/min, and has a one way valve that prevents the pt exhaled gas from entering the reservoir bag and it is considered a "low flow"

Nonrebreathing Mask


Low flow O2 devices are adequate O2 delivery systems only when the pt meets what following criteria?

  • Regular and consistent ventilatory pattern.
  • RR of < than 25 breaths/min
  • Consistent Vt of 300-700 mL

What device is considered high flow and delivers 24-50% O2?

Air-Entrainment Mask


A/O2 ratio




A/O2 ratio




A/O2 ratio




A/O2 ratio




A/O2 ratio




A/O2 ratio




A/O2 ratio




A/O2 ratio




If the Fio2 is > 40% what do you use to calculate for magic box?



If the Fio2 is < 40% what do you use to calculate from magic box?



How do you calculate total flow?

Magic box using current FiO2

take ratio and add together EX: 3:1 3+1=4

take the added ratio and multiply it by the amount of flow that is given that is your total flow.


What device delivers 21-100% O2 at flow rates of 8-15 L/min?

Mist should be visible at all times to ensure adequate flow rates.

Aerosol Mask


What device delivers 21-40% O2 (depending on nebulizer setting) at a flow rates of 8-15 L/min?

Face tent


What device uses 21-100% O2 (depending on nebulizer setting) at flow rates of 8-15 L/min?

used on intubated or tracheostomy pt.

A 50 mL piece of reservoir tubing should be at the end of the T piece preventing air from entering the T piece during inspiration and if the tubing falls off FiO2 may decrease.

Adequate flows are ensured by visible mist flowing out the 50 mL reservoir at all times.

T-Piece/ Briggs adaptor


What device delivers 35-60% O2 (depending on nebulizer setting) at flow rates of 10-15 L/min?

Adequate flows are ensured by visible mist flowing out of the exhalation port at all times.

Tracheostomy Mask (collar)


What device provides close to 100% body humidity to all pt's flows up to 8 L/min are used on infants and up to 40 L/min are used on adults and provides and O2 percentage of up to 80%?

High Flow Cannula


How do you calculate FiO2?

O2 + (air flow * 0.2) / Total Flow = FiO2

EX O2 flow 10 L/min

Air flow 30 L/min (entrained through nebulizer)

Air flow 6 L/min (bleed in)

Total Flow 46 L/min

10 + (36 * 0.2) / 46 = 10 + 7.2 / 46 = 17.2/46 = 0.37 or 37%


How do you calculate the Alveolar Air Equation?

((PB-47 mm hg) (FiO2)) - (PaCO2 * 1.25)


What is the normal range for PA-aO2?

4-12 mm Hg


What are the common mixtures of Helium/Oxygen?

80% Helium : 20% Oxygen

70% Helium: 30% Oxygen


To calculate the actual flow of an 80:20 helium/Oxygen what do you do?

multiply the set flow by 1.8


Flowmeter is at 10 L/min what is the actual flow?

10 * 1.8 = 18 L/min


How do you calculate for a desired flow of 80:20 Helium : Oxygen?

desired flow / 1.8 = need flowmeter set to this flow


Pt needs 12 L/min

1.2/1.8 = 6.6 L/min is what the flowmeter needs to be set on.


To calculate the actual flow of an 70:30 helium/Oxygen what do you do?

multiply the set flow by 1.6


Flowmeter is at 10 L/min what is the actual flow?

10 * 1.6 = 16 L/min


How do you calculate for a desired flow of 70:30 Helium : Oxygen?

desired flow / 1.6 = need flowmeter set to this flow


Pt needs 12 L/min

1.2/1.6 = .75 L/min is what the flowmeter needs to be set on.


What is Nitric Oxide used for to treat?

PPHN in neonates that are 34 weeks gestation or term


What is a common starting dose for NO?

20 parts per million (ppm)


What can happen to a patient receiving NO and not weaned properly?

patient could have a rebound effect


What are the two basic types of hyperbaric chambers?

Fixed multiplace chamber (walk in units can have more patients in)

Portable monoplace chamber (only one person at a time)


What is the hyperbaric chamber usually pressurized at?

3 atm or 3 times atmospheric pressure


What is the physiologic effects of hyperbaric O2 chamber?

  • Elevated PaO2 levels
  • Vasoconstriction
  • New capillary bed formation
  • metabolic alteration of aerobic and anaerobic organism.
  • Reduction of nitrogen bubbles in the blood.

What are the indications for a hyperbaric oxygen therapy?

  • CO poisoning
  • Cyanide poisoning
  • Decompression sickness
  • Gas gangrene
  • Gas embolism
  • Osteonecrosis

HBO treatments usually consist of what?

90 minutes at 2-3 atm. 2-4 times a day


A Galvanic Cell O2 analyzer uses what to chemically reduce O2 to electron flow?

electrolyte gel


A Galvanic Cell O2 analyzer uses what to measure O2 concentration?

A Clark electrode


What affects the Galvanic Cell O2 analyzer?

  • Water
  • positive pressure
  • high altitude
  • a torn membrane
  • lack of electrolyte

A Polarographic O2 analyzer

A _______ polarizes the electrodes to allow O2 reduction to occur, which gives off electron flow.



A Polarographic O2 analyzer is uses what to measure O2 concentration?

Clark Electrode


A Polarographic O2 analyzer is affected by what?

  • Water
  • positive pressure
  • high altitude
  • torn membrane
  • lack of electrolyte gel

What is the diffrences between the Galvanic Cell O2 analyzer and the Polargraphic O2 analyzer?

The electrodes last longer on the galvanic cell analyzer.

The polargraphic analyzer has a quicker response time.


What is the most important aspect to remember for the examination of the analyzers?

That they read 0 when calibrated to room air.


How does the pulse oximeters are devics that measure SaO2?

Principle of spectrophotometry


Light from the probe is directed through a ________ ___ to be absorbed in different amounts, depending on the amount of O2 bound to Hb. The result displayed on the monitor as a percentage of saturation.

Capillary bed


Where can a pulse ox be placed on a pt?


  • finger
  • toe
  • ear


  • ankle
  • foot

What are the causes of inaccurate readings?

  • Low blood perfusion
  • CO poisoning
  • severe anemia
  • hypotension
  • hypothermia
  • cardiac arrest
  • nail polish (blue, green, brown, black)
  • ambient light source such as direct sunlight, phototherapy, and fluorescent lights
  • Dark skin pigmentation

Coocimetery (hemoximetery)

This procedure requires ______ blood to be obtained. The oximeter, part of the blood gas analyzer, is able to measure the amount of Hb, HbO2, and HbCO2 in blood.



HbCO is usually expressed as a percentage of what?

total Hb


HbCO as high as 10% is seen in what patients?

Heavy smokers


HbCO levels > than 20% usually result in what?

Nausea and vomiting


What level of HbCO is considered fatal?