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    Physicians often advise removing gel, acrylic nails, or nail polish before a sleep study. But why? Does it impact pulse oximetry test results significantly? Is there a scientific basis? Keep reading to find out the answers via this blog.

    Sleep study with oximetry

    A pivotal device used in sleep studies, whether conducted overnight or during the day at a sleep center or home, is the pulse oximeter. This essential tool consists of a simple sensor typically placed on the fingertip. Its primary function is to measure oxygen saturation, scientifically termed SaO2, by assessing the amount of oxygen-carrying hemoglobin in the blood.

    The pulse oximeter operates by emitting a red light that traverses through the finger to a light detector on the opposite side. During this process, a portion of the light is absorbed by the finger, while the remaining portion reaches the light detector.

    However, the efficacy of the pulse oximeter can be compromised under certain conditions. For instance, wearing artificial nails, especially those made of acrylic, poses a hindrance to the sensor’s accuracy. Acrylic nails create a barrier between the sensor and the blood in the finger, impeding the transmission of light to the detector. Similarly, nail polish, especially in colors like red, can affect the sensor’s ability to accurately measure blood oxygen levels. This alteration in light absorption can lead to an inaccurate baseline reading, particularly when the patient tests with acrylics or nail polish.

    In a sleep study, it’s crucial to observe any change from the baseline oxygen reading. If there’s an issue with the initial oxygen measurement due to obstructed sensors, the sleep technologist overseeing the study can usually detect this signal and rectify it before it becomes a significant problem. In cases where nails obstruct the sensor, the technician might opt to reposition the pulse oximeter to a toe or earlobe to obtain accurate readings.

    However, if the sensor fails to acquire any signal during the polysomnography, technical difficulties might necessitate canceling the study instead of continuing with incomplete or unreliable recordings.

    In essence, the pulse oximeter is a vital component in sleep studies, offering insights into oxygen saturation levels. Yet, its accuracy can be affected by factors such as artificial nails and nail polish, necessitating caution during testing to ensure accurate and reliable readings for an effective sleep study evaluation.

    Do you have to remove my nail polish, gels, or acrylics before the sleep study?

    While it’s preferable to avoid acrylic nails or remove them before the sleep study, we can proceed with the study even if they’re still on. Similarly, it’s advised to remove red nail polish, which is relatively easier compared to acrylics, before the study for optimal results. 

    Study 1

    In a 2007 prospective clinical-experimental trial conducted in an ICU with mechanically ventilated and critically ill patients, researchers examined the impact of acrylic fingernails on oxygen saturation measurements using pulse oximeters. Patients had SpO2 measured three times in both standard and sideways positions at their natural nails, followed by SpO2 measurements at the acrylic fingernail in the same manner.

    The study aimed to assess the accuracy (mean difference) and precision (standard deviation) of these measurements to determine any discrepancies. The findings indicated that acrylic fingernails might interfere with oxygen saturation measurements, leading to significant inaccuracies. However, these inaccuracies were deemed clinically irrelevant, meaning they were not substantial enough to impact patient care.

    The study suggested that the compromised accuracy could be attributed to a diminished signal-to-noise ratio in patients with acrylic fingernails. This effect seemed to be further influenced by the wavelengths used in the pulse oximeter.

    Therefore, the study concluded that while acrylic fingernails might slightly affect the precision of oxygen saturation readings, the level of inaccuracy was not clinically significant. However, to ensure precise and accurate measurements with pulse oximetry, removing artificial acrylic fingernails was recommended, as this could potentially improve the accuracy of SpO2 readings [1]. 

    Study 2

    In 2013, researchers delved into the impact of nail polish colors and acrylic nails on the accuracy of saturation readings obtained through a pulse oximeter. To conduct this investigation, fifty non-smoking volunteers participated in the study. Their fingers were sequentially numbered from the little finger of the right hand as 1 to the little finger of the left hand as 10.

    Alternate fingers were treated: clear, red, brown, and black nail polish were applied, while the 5th finger on one hand had an acrylic nail. The corresponding fingers on the other hand served as controls. The study then measured oxygen saturation using a pulse oximeter.

    The results revealed that fingers adorned with clear nail polish, red nail polish, and acrylic nails displayed consistent saturation values. The mean saturation values for these variations did not exhibit any significant differences. However, when black and brown nail polish was applied, only 12% and 64% of those nails, respectively, recorded saturation values that were notably different.

    Consequently, the study concluded that dark-colored nail polish, particularly black and brown, should be removed before determining SpO2. This removal was suggested to ensure the accuracy of readings obtained through pulse oximetry. The inconsistency in obtaining accurate saturation values with darker nail polish hues emphasized the importance of their removal to attain precise and reliable measurements [2].

    What if you use glittered nail polish?

    In a 2019 randomized clinical trial, researchers aimed to investigate how various colors of glittered nail polish affect oxygen saturation (SpO2) levels in healthy individuals. The study involved 30 healthy students with SpO2 levels of 95% or higher, free from nail bed complications and issues related to blood flow in the environment. 

    The participants’ SpO2 levels were initially measured on all ten fingers after they sat and rested for 10 minutes in a room with normal temperature. Subsequently, they randomly applied ten different colors of glittered nail polish to their fingernails. Post-application, the SpO2 levels were measured again after the nail polish had dried.

    Interestingly, the study found that out of the ten glittered nail polish colors tested, dark green and purple did not notably alter the SpO2 readings. However, the application of all other colors resulted in a slight reduction in SpO2 levels. Nonetheless, these changes were deemed insignificant in clinical terms, as the difference in SpO2 levels before and after nail polish application was within an acceptable range (less than a 2% change).

    Consequently, the study’s conclusion highlighted that the use of various colors of glittered nail polish does not produce clinically significant changes in pulse oximetry measurements among healthy subjects. Therefore, the routine removal of glittered nail polish in clinical, surgical, and emergency settings is deemed unnecessary based on these findings.

    Final Thoughts

    If you’re unsure whether to remove nail polish or acrylic nails before overnight oximetry, consult your doctor for guidance. For further clarification, reach out to the sleep study specialists at Apurva Advanced Medical Care in Prescott, Arizona, US. They can provide expert advice on this matter.