Chapter 10; Assessment of Respiratory Function

Chapter 10; Assessment of Respiratory Function

 

Complete Chapter Questions With Answers

 

Sample Questions Are Posted Below

 

MULTIPLE CHOICE

 

1. A pulse oximeter differentiates oxyhemoglobin from deoxygenated hemoglobin by which of the following methods?

a.	Relating cyclical changes in light transmission through the sampling site
b.	Shining and comparing two wavelengths of light through the sampling site
c.	Direct measurement by a heated polarographic electrode applied to the skin
d.	Using a color sensing device that absorbs one wavelength of light through the skin

 

 

ANS:   B

A pulse oximeter uses spectrophotometry to differentiate between oxyhemoglobin and deoxygenated hemoglobin. Two wavelengths of light (660 nm and 940 nm) are shined through a sample site. Oxyhemoglobin absorbs more light at 940 nm (infrared light [IR]) than does deoxygenated hemoglobin. Deoxyhemoglobin absorbs more light at 660 nm. The use of cyclical changes in light transmission measured at the sampling site is the method to determine the pulse rate with a pulse oximeter. A heated polarographic electrode is used for transcutaneous partial pressure of oxygen (PtcO₂) measurements. A color sensing device is used to detect the amount of carbon dioxide in exhaled gas.

 

DIF:    1                      REF:    pg. 177

 

2. An arterial blood gas should be done to confirm pulse oximetry findings less than a minimum of _____________.

a.	60%
b.	70%
c.	80%
d.	90%

 

 

ANS:   C

When a patient’s oxygen saturation measured by pulse oximeter (SpO₂) is less than 80% an arterial blood gas should be drawn to confirm the patient’s oxygenation status because a pulse oximeter is generally accurate for oxygen saturations greater than 80%.

 

DIF:    1                      REF:    pg. 177

 

3. A pulse oximeter reading will be most accurate when used with a patient in which of the following situations?

a.	An intensive care unit patient with hyperbilirubinemia
b.	A hypotensive patient receiving peripheral vasoconstrictors
c.	An emergency department patient with evidence of smoke inhalation
d.	An open heart patient receiving extracorporeal membrane oxygenation

 

 

ANS:   A

Hyperbilirubinemia does not appear to affect pulse oximetry measurements as do low perfusion states, which are caused by the use of peripheral vasoconstrictors or extracorporeal membrane oxygenation (ECMO). Carbon monoxide poisoning will lead to an overestimation of oxygen saturation measured by pulse oximeter (SpO₂).

 

DIF:    1                      REF:    pg. 177

 

4. A patient arrives in the emergency department via ambulance following rescue from a house fire. The instrument that would be most appropriate to assist the respiratory therapist in assessing this patient’s oxygenation status is which of the following?

a.	Capnograph
b.	Pulse oximeter
c.	Calorimeter
d.	CO-Oximeter

 

 

ANS:   D

Laboratory CO-oximeters measure four types of hemoglobin: oxyhemoglobin (O₂Hb), deoxygenated hemoglobin (HHb), carboxyhemoglobin (COHb), and methemoglobin (MetHb). This is beneficial for patients who are suffering from smoke inhalation. The CO-oximeter provides the actual O₂Hb and the COHb. Carbon monoxide produces an erroneously high oxygen saturation measured by pulse oximeter (SpO₂). Therefore, if smoke inhalation is suspected, a CO-oximeter should be used to evaluate the oxygen saturation. Capnography is the measurement of carbon dioxide concentrations in exhaled gases and is used to assess proper airway placement. Calorimetry allows the clinician to estimate energy expenditure from measurements of oxygen consumption (O₂) and carbon dioxide production (CO₂). This measurement may be useful when weaning a patient from mechanical ventilation.

 

DIF:    2                      REF:    pg. 178

 

5. While trying to use a finger probe to assess a patient’s oxygenation status, the respiratory therapist finds that the pulse rate and the ECG monitor heart rate are not consistent and the oxygen saturation measured by pulse oximeter (S_pO₂) reading is blank. The patient is awake, alert, and in no obvious respiratory distress. The respiratory therapist should first take which of the following actions?
6. Change the probe site.
7. Draw an arterial blood gas.
8. Adjust the probe position on the finger.
9. Remove probe, perform a capillary refill test.

a.	1 and 2 only
b.	2 and 3 only
c.	3 and 4 only
d.	1 and 4 only

 

 

ANS:   C

The fact that the patient is awake, alert, and in no respiratory distress decreases the likelihood that the problem is with the patient. Therefore, the first action in this case should not be to draw an arterial blood gas (ABG). In cases where the pulse oximeter cannot identify a pulsatile signal, the oxygen saturation measured by pulse oximeter (SpO₂) reading may not be present. This could be alleviated by adjusting the probe position on the finger. Absent SpO₂ readings could also be due to low perfusion states. Performing a capillary refill test on the finger being used for the probe would show whether or not the finger has adequate blood flow. If this is true, the next step would be to change the site.

 

DIF:    3                      REF:    pg. 177