Page 303 - Saunders Comprehensive Review For NCLEX-RN

phase 1 (heard as the blood pulsates
through the vessel when air is released
from the BP cuff and pressure on the
artery is reduced) as the systolic
pressure, and the beginning of the fifth
Korotkoff sound at phase 5 as the
diastolic pressure.
i. BP readings obtained electronically with
a vital sign monitoring machine should
be checked with a manual cuff if there
is any concern about the accuracy of
the reading.

When taking a BP, select the appropriate

cuff size; a cuff that is too small will yield a falsely
high reading, and a cuff that is too large will yield a
falsely low one.
VI. Pulse Oximetry
A. Description
1. Pulse oximetry is a noninvasive test that registers the
oxygen saturation of the client’s hemoglobin.
2. The capillary oxygen saturation (Sao ) is recorded as a
2
percentage.
3. The normal value is 95% to 100%.
4. After a hypoxic client uses up the readily available
oxygen (measured as the arterial oxygen pressure,
Pao , on arterial blood gas [ABG] testing), the reserve
2
oxygen—that is, oxygen attached to the hemoglobin
(Sao )—is drawn on to provide oxygen to the tissues.
2
5. A pulse oximeter reading can alert the nurse to
hypoxemia before clinical signs occur.
6. If pulse oximetry readings are below normal, instruct
the client in deep breathing technique and recheck the
pulse oximetry.
B. Nursing Considerations
1. A vascular, pulsatile area, such as the fingertip or
earlobe, is needed to detect the degree of change in
the transmitted light that measures the oxygenated
and deoxygenated hemoglobin.
2. Factors that affect light transmission also affect the
measurement of SpO .
2
3. Some factors that affect light transmission can include
sensor movement, fingernail polish, hypotension,
anemia, or peripheral vascular disorders.
C. Procedure

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