Pulse oximetry

1. PREPARED BY
DR.SHALI B.S
PROFESSOR
MAMATA COLLEGE OF
NURSING.KHAMMAM

2.  A pulse oximeter is a medical device that
indirectly measures the oxygen saturation of a
patient's blood and changes in blood volume in
the skin.
 It is often attached to a medical monitor so
staff can see a patient's oxygenation at all time.

3. A source of light originates from the probe at two
wavelengths (650nm and 805nm).
The light is partly absorbed by haemoglobin, by
amounts which differ depending on whether it is
saturated or de-saturated with oxygen.
By calculating the absorption at the two wavelengths
the processor can compute the proportion of
haemoglobin which is oxygenated.
Where flow is sluggish (eg hypopovolaemia or
vasoconstriction) the pulse oximeter may be unable to
function.

4.  Monitor adequacy of oxygen saturation; quantify
response to therapy.
 Monitor unstable patient who may experience
sudden changes in blood oxygen level.
 Evaluation of need for home oxygen therapy.
 Determine supplemental oxygen needs at rest,
with exercise, and during sleep.
 Need to follow the trend and need to decrease
number of ABG sample drawn.
 Increased body temperature,
 acidosis.

5.  Decreased temperature
 Increased bilirubin,
 low perfusion or Sao2 < 80% may alter light
absorption and interfere with results.

6.  A pulse oximeter is useful in any setting where a
patient's oxygenation is unstable including intensive
care, operating, recovery, emergency and hospital
ward setting
.
 A pulse oximeter is used to monitor oxygenation, it
cannot determine the metabolism of oxygen, or the
amount of oxygen being used by the patient
 Pulse oximeters are of critical importance emergency
medicine and are also very useful for patients with
respiratory problems, especially COPD, or for
diagnosis of some sleep disorders such as hypoapnea.

7.  Assess patient's haemoglobin. Sao2 may not correlate well
with PaO2 if haemoglobin is not within normal limits.
 Remove patient's nail polish because it can affect the ability
of the sensor to correctly determine oxygen saturation,
particularly polish with blue or dark colours.
 Correlate oximetry with ABG values.
 Display heart rate should correlate with patient's heart rate.
 To improve quality of signal, hold finger dependent and
motionless (motion may alter results) and cover finger
sensor to occlude ambient light.

8.  Assess site of oximetry monitoring for
perfusion on a regular basis, because pressure
ulcer may occur from prolonged application of
probe.
 Document inspired oxygen or supplemental
oxygen and type of oxygen delivery device.
 Accuracy can be affected by ambient light, I.V.
dyes, nail polish, deeply pigmented skin,
patients in sickle cell crisis, jaundice, severe
anemia, and use of antibiotics such as sulfas.

9.  Abnormal haemoglobins
 I.V. dye,
 Exposure of probe to ambient light,
 low perfusion states,
 Skin pigmentation,
 Nail polish or nail coverings, and
 Nail deformities such as severe clubbing.