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PULSE OXIMETER-

THIS ARTICE WILL TELL YOU ALL ABOUT OF PULSE OXIMETER.

WHAT CAN MEASURE PULSE OXIMETER-

  1. SpO2 (PERIPHERAL OXYGEN SATURATION)
  2. HR (HEART RATE)
  3. PI (PERFUSION INDEX)

IN THIS READING

SpO2 IS 98% & PULSE RATE IS 72.

THEN WHAT IS THE NORMAL Spo2 & PR.

ACCORDING TO WHO NORMAL SpO2 RANGE FROM  95% TO 100%.

IF THE SpO2 IS 94% OR BELOW TREATMENT IS REQUIRED QUICKLY.

IF SpO2 IS BELOW 90% THEN IT IS CLINICAL EMERGENCY.

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NORMAL HR = 72-100 BEATS/MIN

WHAT IS OXYGEN SATURATION-

OUR RED BLOOD CELLS CONTAIN HEMOGLOBIN WHICH CARRY THE OXYGEN. HOW MUCH Hb IS BOUND TO RED BLOOD CELLS IS KNOWN AS OXYGEN SATURATION.

IS ARTERIAL & VENOUS BLOOD CONTAIN DIFFERENT AMOUNT OF OXYGEN-

NORMALLY,ONLY 75% OF Hb OF VENOUS BLOOD IS SATURATED WITH OXYGEN & IN ARTERIAL BLOOD 98% OF Hb IS SATURATED WITH OXYGEN.

SO,BECAUSE OF THESE ARTERIAL BLOOD IS BRIGHT RED & VENOUS BLOOD IS DARK RED.

DO YOU KNOW HOW PULSE OXIMETER WORK-

PULSE OXIMETER HAS A PAIR OF LIGHT EMITTING DIODE. ONE LED IS RED WITH WAVELENGTH OF 660nm & OTHER IS INFRARED WITH WAVELENGTH OF 940nm.ABSORPTION OF LIGHT AT THESE WAVELENGTHS DIFFERS BETWEEN BLOOD LOADED WITH OXYGEN & BLOOD LACKING OXYGEN.OXYGENATED Hb ABSORB MORE INFRARED LIGHT & ALLOW MORE RED LIGHT TO PASS THROUGH.WHILE DEOXYGENATED Hb ALLOW MORE INFRARED LIGHT & ABSORB MORE RED LIGHT.

THE AMOUNT OF LIGHT THAT IS TRANSMITTED IS MEASURED.THE RATIO OF RED LIGHT MEASUREMENT TO INFRARRED LIGHT MEASUREMENT IS CALCULATED BY PROCESSOR THEN CONVERTED TO SpO2.

FACTORS WHICH INCREASE ACCURACY OF PULSE OXIMETER-

PHOTO PLETHYSMOGRAPH INCREASE ACCURACY OF PULSE OXIMETER.

NEWER OXIMETER HAVE PHOTO PLETHYSMOGRAPH WAVEFORM WHICH USE MULTIPLE WAVELENGTHS OF LIGHT THAT QUANTIFY METHEMOGLOBIN,CARBOXYGLOBIN & TOTAL HEMOGLOBIN CONTENT IN BLOOD.

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PERFUSION INDEX-

IT IS THE RATIO OF PULSATILE BLOOD FLOW(ARTERIAL FLOW) TO NON-PULSATILE BLOOD FLOW(VENOUS & CAPILLARY FLOW).

IT IT BELOW 0.4% IN PULSE OXIMETER IT MEANS WEAK PULSE STRENGTH & POOR PERFUSION & READING WOULD NOT BE RELIABLE.

CAUSE OF POOR PERFUSION- PERIPHERAL VASCULAR DISEASE,DIABETES,OBESITY,BLOOD CLOTS.

HOW ACCURATE IS PULSE OXIMETER-

WE CAN NEVER SAY A PULSE OXIMETER IS 100% ACCURATE. IT CAN SHOW ±2% ERROR.

FACTOR THAT CAN AFFECT PULSE OXIMETER READING-

  1. NAIL POLISH
  2. HENNA
  3. ANY KIND OF PIGMENT ON SKIN
  4. MOVEMENT
  5. CARBON MONO OXIDE POISONING
  6. POOR PERFUSION

PULSE OXIMETER CAN’T DISTINGUISH BETWEEN CARBON MONO OXIDE & OXYGEN & READING WOULD BE INACCURATE.READING WOULD BE FALSE UPTO 4HRS AFTER RECENTLY SMOKE FROM FIRES OR HEAVY TRAFFIC ENVIRONMENT.

HOW MUCH O2 IS BINDED TO Hb IN 100% OF SATURATION-

Hb CAN NORMALLY BIND 1.34 mL OF O2/gm of Hb. NORMAL Hb IS 15gm/dL. THEN NORMAL OXYGEN BINDING CAPACITY 20 mL/dL BLOOD IF SATURATION IS 100%.

WHAT HAPPEN IF Hb DECREASE-

O2 CONTENT ALSO DECREASE SO THERE  WOULD BE NO CHANGE IN O2 SATURATION.

WHAT IF PERSON HAVE ABNORMAL Hb MOLECULE-

LIKE,IN SICKLE CELL ANEMIA IN SUCH CASES ARTERIAL BLOOD GAS ANALYSIS PaO2 & SaO2 IS NECESSARY.

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WHAT IS SaO2-

SaO2 IS OXYGEN SATURATION READING DERIVED FROM ABG ANALYSIS ( ARTERIAL BLOOD GAS ANALYSIS)

WHICH IS MORE RELIABLE – SpO2 OR SaO2

OXIMETER IS NON INVASIVE METHOD FOR MEASURE OXYGEN SATURATION & CONSIDERED ACCURATE & RELIABLE IN THE RANGE OF 90%-100%.

HIGHEST ACCURACY AT 90%-100% O2 SATURATION,INTERMEDIATE AT 80%-90% SATURATION & AT LOWEST BELOW 80%.

FDA SAYS– If an FDA-cleared pulse oximeter reads 90%, then the true oxygen saturation in the blood is generally between 86-94%.

WHICH OXIMETER YOU SHOULD BUY-

RECOMMENDED TO BUY FDA APPROVED OXIMETER WITH PI & PHOTOPLETHYSMOGRAPH.

YET,CHEAPER OTC OXIMETER ARE ALSO AVAILABLE YOU CAN ALSO GO FOR THEM.

 

 

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