Handheld Pulse Oximeter - 66 Series FAQ


The PC-66H (Battery Operated Handheld Pulse Oximeter) is powered by three AA Batteries. The batteries are included with your device. Please replace used batteries with 1.5V AA batteries.

Depends on the usage scenario. For continuous monitoring, typically the fully charged battery or new AA batteries will last for 8 hours. For spot checking, batteries should last a few days or weeks depending on the frequency of use.

8 hours.

When replacing your device’s batteries, please ensureyou replace all 3 batteries. Do not replace just one or two.

The possible reasons are:

- Using the wrong charging cable

- Battery is removed

- Defective cable(s)

- Defective battery

Yes, you can still operate your oximeter while it is plugged in and charging.

Due to the effects that COVID-19 has on overall lung function and your body’s ability to obtain oxygen, monitoring SpO2 is vital to managing COVID-19 both during and after infection. Our pulse oximeters allow users to monitor their oxygen saturation from the comfort of home, alerting them to possible health issues.

Here is a quick list of those who may benefit from having a Pulse Oximeter at home. Click here for more information!

- Musicians

- Athletes

- Parents with Infants

- Users diagnosed with COPD or Asthma.

- Users diagnosed with Sleep Apnea

- Users with cardiac disorders (chronic or acute)

- People seeking to improve their daily blood oxygen saturation

- Children aged 2-12 (learn more)

- Individuals recovering from injury or surgery (How Oxygen Levels can Affect Healing)

- People recovering from illness (Ex: the flu or COVID-19)

Sp02 is an abbreviation for arterial oxygen saturation. Please Keep in mind Sp02 is a measurement of arterial blood (not venous blood) because arteries contain the red blood cells that have most recently passed through the lungs, where they collect oxygen. PR refers to pulse rate, the number of times your heart beats per minute. PI refers to perfusion index, which is the ratio of the pulsatile blood flow to the non-pulsatile or static blood in peripheral tissue.

Oxygen Desaturation Index, otherwise known as ODI, is the measure of insufficient blood oxygen levels, specifically during sleep.

Pulse oximetry measures the percent of blood hemoglobin that is oxygen rich. It functions by passing a red beam of light into the fingertip. The oxygen level is then determined by measuring how much light passes through the fingertip vs how much is absorbed. 

For more information on how Pulse Oximetry and Sensors work, check out this blog.

Pulse Oximeters have a variety of uses! Even those without respiratory conditions find them to be useful and necessary in daily life. For example, athletes and musicians often use pulse oximeters to monitor their oxygen intake and lung function. For more information on who can benefit from using a pulse oximeter, click here.

We suggest purchasing the PC-66L Rechargeable Handheld Pulse Oximeter for those who need to use their oximeter overnight.

Both the PC-66H and the PC-66L can technically be used for continuous overnight monitoring. However, using then rechargeable pulse oximeter tends to save users money in the long term as it eliminates the need to purchase or replace AA batteries.

Keep in mind, you can use the oximeter while it is charging!

While it is not necessary to do so, many parents have begun monitoring their infants overnight and during naps as a preventative measure against Sudden Infant Death Syndrome (SIDS). Low oxygen levels can be a key early indicator of major issues that are often involved in SIDS. Consult a pediatrician if there is concern. Click here to view our Infant Foot Sensor#72.

Both of our PC-66 Series Handheld Pulse Oximeters are equipped with the ability to sound an alarm if your reading drops below the threshold value. You can manually set your own values in the device to better suit your needs and lifestyle. For how to set up the alarm, please watch this video.

Muting the alarm will only block out the standard beeping. If your readings go below your set threshold values, the oximeter will override the mute and sound an alarm to alert you.

The PC-66Handheld Pulse Oximeter will over-write the mute function when the followings occur:

- An alarm event occurred

- Sensor has fallen off

- Device was turn off and on again

CMI Health has sensors for continuous monitoring and spot-checking for a wide range of ages. The sensor comparison chart will help you identify the sensor best suited for your unique needs – that can be found here. If you are still confused as to which sensor to purchase, please feel free to reach out to our customer service team at info@cmihealth.com. We are always happy to assist.

We suggest using the Soft Rubber/Silicone sensors #84 for overnight use.

Our overnight sensor is designed to fit comfortably and securely on the user's finger during sleep. The stronger grip helps to prevent the sensor from moving or falling off during unconscious movement.

When properly using, storing, and caring for your sensor, it should last for a very long time. To clean the sensor, use rubbing alcohol.

Though the sensor cable port may look similar to another brands’ device port, the program and hardware are different. CMI Health’s sensors are only compatible with CMI Health PC-66 Handheld Pulse Oximeter series.

This sensor was designed for finger or foot use (the infant foot wrap sensor) only. Using this sensor on any other part of the body may result in inaccurate readings. We strongly suggest following the instructions found in the user manual.

To clear the device memory, first turn on the device via the power button. Once the device is on, hold down the “mute button”. This will pull up the device data records. From here, hold down the mute button again. A notification will pop up that says, “Are you sure you want to delete all”. Use the arrow buttons to scroll to the “Yes” option. Click the “Mode” Button to select “Yes”. This will delete all recorded data. You can then use the power button as a “Back” button to return to the home screen. If you are still unsure of how to clear the data, please click here to view our video tutorial.

You can share medical reports with a physician through the Oximeter Data Manager desktop program.  Once the data is uploaded to the application you can export the data as a report by going to the Data Review tab, selecting Sp02 Continuous, highlight the record you want to share, select the Chart tab, select report.  You can print the report or save the report as a pdf, through the print options, to email the report to a physician.

Please check if you are using the USB data cable, not the Power cable. The correct USB data cable should have a bulky end that plugs into the PC and should be labeled with “USB”. The USB data cable is included with every PC-66H and PC-66L unit.

If you are using the correct USB data cable, but still getting COM error. Please search and run “Device Manager” in the Windows Search. Check if you have Prolific USB-to-Serial Comm Port under Ports, as shown below. If not please download and run this USB Driver, choose Repair if prompted, and check Device Manager when the installation has been finished.

If you have the Prolific USB-to-Serial Comm Port show up, please make sure you have the device ON with the data upload screen at all times when you perform data upload in the software. You will need to finish all uploading process, including data selection and uploading to the patient record, while the device data upload screen is ON.

Our devices are manufactured under international standards, to be more specific, the Pulse Rate Accuracy is ±2bpm or ±2% (whichever is greater) and the SpO2 accuracy is not greater than 3% for SpO2 range from 70% to 100%

Pulse Oximeters are highly accurate when used according to best practices. 

The following variables below can impact oximeter accuracy…

- Brightness of Light

- Probe Placement

- Pressure on the Wrist

- Nerve-Blocking Medications

- Movement

- Artificial Nail Accessories

- Other Health Condition 

For more detailed information on each of these factors and how to mitigate inaccuracy in your oximeter readings - read our blog post on Factors That Affect Pulse Oximeter Readings.

When it comes to which finger you should use a pulse oximeter on, the answer isn’t as cut and dry as one may initially believe. Based on the results of one specific study, it was found that the highest SpO2 value was measured on a subjects’ right middle fingers.

However, this variance was very slight when compared to the readings of all the other fingers. For this reason, it’s believed that you will obtain similar measurements regardless of which finger you place the probe on. It is still a good practice to use a more uniform digit like the index or middle finger rather than the pinky or thumb as this helps to reduce the margin for error. For more information on which finger you should use, please click here.

Our oximeters are manufactured to international quality standards. If the readings from your PC-66 Handheld Pulse Oximeter are slightly off from other pulse oximeter’s readings, the possible reasons are:


- Within 3% difference should be normal. According to international manufacturing standards, SpO2 accuracy is within 3% between 70% to 100%.
- Your device is defective and or experiencing some sort of malfunction.
- Your sensor or converter cable is defective and or malfunctioning.


Please contact CMI Health, Inc. customer service: 888-985-1125 or info@cmihealth.com for specific device or quality concerns.

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