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Choice Medical Handheld Pulse Oximeter MD300I Basic Operation

Outer View

Fig.2.1 Front view

Fig.2.2 Rear view

Install the batteries

The oximeter can be powered by 2 AA-Size alkaline batteries (which will typically provide 50 hours of continuous operation), or by the optional rechargeable NiMH battery pack.

When battery power is lower than 2.4V, the sign will flicker in its display area. Replace the battery (or rechargeable NiMH battery pack) as soon as possible. The installation steps are shown as Fig. 2.3.

Be sure to insert the batteries in the correct polarity, as indicated by polarity marking (+ and -) inside the battery compartment.


Connect the sensor

Connect the oximeter sensor to the top of the oximeter as shown in Fig. 2.4. Ensure that the sensor is firmly plugged in.



Clip the sensor to the patient's finger, and ensure that the patient's nail surface is facing upward, as shown in Fig. 2.5.

Fig.2.5 Placement of the finger

Power on the oximeter

Press the function key (left key) to power it on. Several seconds later, the measurement value will appear.

Notice: To maintain the highest degree of accuracy, it is recommended that the finger and the oximeter sensor/probe is kept as still as possible.

Brightness adjustment

When you press the function key (left key) for more than one second, the brightness level headed with “Br” will be shown on the top right of the screen. You can adjust the brightness by degrees by pressing the setting key (right key). There are 10 levels of brightness. The default is level four.


Mode switch

After turning on the oximeter, each time the function key (left key) is pressed, the oximeter will switch to another display mode, as shown below.

Factors that may affect the measurement

During operation, the accuracy of oximetry readings can be affected by the following factors:

Instrument performance depends on the pulsatile character of the artery. The measurement would not be considered reliable and accurate if the following conditions are present during measurement:

  • Shock or cardiac arrest
  • Temperature of the digit
  • After the administration of a cardiovascular drug
  • Anemia
  • Evidence of ventilation-perfusion mismatch

Instrument performance depends on the wavelength absorption for oxyhemoglobin and deoxyhemoglobin. If there are substances absorbing the same wavelength, this would induce false or low SpO2 values. The following may affect these values:

  • carboxyhemoglobin
  • methemoglobin
  • methylene blue
  • Indigo carmine

Extremely high illumination could affect the SpO2 measurement. Use a semi-translucent or opaque cover to shield the sensor.

Other factors

  • High-frequency electrosurgical interference from external devices, including defibrillators.
  • Placement of a sensor on an extremity that currently has installed a blood pressure cuff, arterial catheter, or intravascular line;
  • The patient has hypotension, severe vasoconstriction, severe anemia, or hypothermia;
  • An arterial occlusion proximal to the sensor.


  • Use only SpO2 sensors provided by manufacturer. Other SpO2 sensors may cause improper performance.
  • Do not use an SpO2 sensor with exposed optical components.
  • Excessive patient movement may cause inaccurate measurements.
  • Tissue damage can be caused by incorrect operation or misusing sensor; for example, by wrapping the sensor too tight. Inspect the sensor site to ensure the skin's integrity and the adhesion position of the sensor is correct. More frequent inspection should be taken if necessary.
  • Loss of pulse signal can occur in any of the following situations:
    • The sensor is too tight;
    • There is excessive illumination from light sources such as a surgical lamp, a bilirubin lamp, or sunlight;
    • A blood pressure cuff is inflated on the same extremity as the one to which an SpO2 sensor is attached.

Storage and Transportation

Storage: Storage Temperature -20°C - 70°C. Relative Humidity < 90%

Transportation: Transport by airline, train or vessel after packing according to request.

Package: Pack the product with the hard bag, and put the foam between the inner box and the cartoon to alleviate the shake.

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