Background Knowledge Of Pulse Oximetry

Oxygen Saturation

Outline 

Background Knowledge ◦ ◦ ◦ ◦ ◦ ◦ ◦

Definition of special terms Example of SaO2 Respiration Range of heart rate Transportation of oxygen – the blood Hemoglobin Arterial blood versus venous blood

Background Knowledge Definition of special terms (Medical) 

SO2 Oxygen saturation  Artery + Venous

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SaO2

Arterial oxygen saturation  95 – 98%

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SvO2Venous oxygen saturation  60 – 80%

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SpO2

Pulse oxygen saturation  Arterial oxygen saturation  Pulse oximeter used

Background Knowledge Example of SaO2  Each hemoglobin is able to carry 4 oxygen molecules  As a result, when there are 100 hemoglobin, a total number of 400 oxygen molecules can be carried  When the number of oxygen carried = 380 then SaO2 = 380/400 * 100% = 95%

Background Knowledge Respiration 

Respiration = the process of gas exchange ◦ Takes oxygen in and carbon-dioxide out

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Two levels of respiration ◦ Internal respiration (cellular respiration) The use of O2 by our cells CO2 is the waste product

◦ External respiration (ventilation) The exchange of O2 and CO2 between the atmosphere and body tissues

Background Knowledge Range of heart rate (per minute)  Elderly : 55 - 60  Young people : 70 – 90  Below 8-year-old : 80 – 140 ◦ ◦ ◦ ◦

4–7 years old : 80 – 100 2-3 years old : 100 – 120 1-year-old : 110 – 130 Neonate : 120 - 140

Background Knowledge Transportation of oxygen – the blood White blood cell (minority)  Red blood cell (majority) 

◦ Hemoglobin 

Related illness – hypoxia ◦ Malfunction of hemoglobin Carry other elements other than oxygen in artery system

◦ Detection using SaO2 measurement

Background Knowledge Hemoglobin

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4O2 + Hb <——> nH+ + Hb(O2)4

Background Knowledge Arterial blood versus venous blood 

Colour

◦ Artery: bright-red ◦ Venous : dark -red

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SO2

◦ SaO2 : 95-98% ◦ SvO2 : 60-80%

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As a result, the oxygen saturation determine the colour of both arterial and venous blood