 
Pulse oximeter is a non-invasive medical device.
which tells about two parameters.
first is pulse oxygen saturation
whose symbol is SpO2.
and second is pulse rate
whose symbol is PR.
pulse oxygen saturation refers
to the amount of oxygen in blood.
whose normal value range is 95%-100%
if it becomes less than 90%
then it is called Hypoxemia
in which patient feels breathing difficulty
along with chest pain
which is a symptom of Covid-19 also
oxygen therapy is required for it's treatment
but in some patients of Covid-19
no symptoms has been observed
despite having less than 80% of SpO2
that is no breathing problem despite being hypoxemia
so this condition is called silent hypoxemia
or happy hypoxia
this may be recovered automatically
or may be a cause of sudden cardiac failure
and patient may die suddenly
causes of hypoxemia other than Covid 19 are
anemia, lung problem(asthma, COPD), & heart defects
second parameter is pulse rate
which is equal to heart rate
i.e. heart beats per minute
it's normal value is 60-100 beats per minute.
if it is more than 100bpm then it is called tachycardia
which mainly occurs due to
hypertension, hyperthyroidism or anemia
and if it is less than 60bpm then it is called bradycardia
which mainly occurs due to
hypothyroidism, heart tissue damage or rheumatic fever
some noticeable points before using pulse oximeter
first is not for children below 4 years old
nail polish causes inaccuracy in readings
third one is
for getting accurate reading
one should use middle finger of right hand
fourth one is
do not use in patients instantly
coming after MRI or CT scan
fifth one is
patients who taking dopamine
or anesthetics like lidocaine
pulse oximeter does not give accurate readings in those
and sixth one is
light emitted from pulse oximeter is harmful to the eyes
so one should not stare at the light
and at last
talking about best pulse oximeter
before purchasing a pulse oximeter
3 points should be taken into consideration
first Accuracy
2nd Resolution
3rd Measuring range
generally, all pulse oximeter
have similar accuracy, resolution and measuring range
 
 
 
 
 
thus as per technical specifications
all pulse oximeter are similar.
if you have got a pulse oximeter
whose accuracy deviation is less than +_2%
then name the brand in comment box
