Before any surgical procedure, patients must remove all nail coatings, including polish, gels, and artificial nails. This is a strict safety measure because a patient’s circulation and oxygen levels must be monitored continuously and accurately throughout the operation. The requirement ensures the proper function of monitoring equipment and allows medical staff to perform quick physical checks. Failing to prepare the nails can lead to misdiagnosis or delayed recognition of a medical complication during anesthesia.
Understanding Pulse Oximetry
One of the primary tools affected by nail coatings is the pulse oximeter, a non-invasive device typically clipped onto a finger or toe. This instrument measures the percentage of hemoglobin in the blood that is saturated with oxygen, known as the SpO2 level. The device works by emitting two distinct wavelengths of light: red light (around 660 nanometers) and infrared light (around 940 nanometers).
Oxygenated hemoglobin absorbs more infrared light and allows more red light to pass through the tissue. Conversely, deoxygenated hemoglobin absorbs more of the red light and less of the infrared light. The oximeter sensor measures the subtle differences in the absorption ratio of these two light types as the blood pulses through the capillaries. This measurement allows the device to calculate the oxygen saturation level, providing real-time data to the surgical team about a patient’s respiratory function.
How Nail Coatings Obscure Accurate Readings
Nail coatings interfere with the pulse oximeter by altering the transmission of light waves. Opaque colors, particularly dark shades such as black, blue, or purple, are problematic because they absorb or scatter a significant amount of the emitted red and infrared light. This absorption prevents the sensor from receiving enough light to calculate a reliable ratio.
When the light is heavily absorbed by the polish, the device may mistakenly interpret the lack of transmitted light as a sign of low oxygen saturation. This can lead to a falsely low reading, known as artifactual hypoxemia. Thick coatings, including gel polish, dip powder, and acrylic nails, also create a physical barrier that diffuses the light, which can cause the reading to fail entirely or produce erratic numbers.
Even clear or light-colored polishes can pose a problem due to their thickness or reflective properties, potentially leading to inaccurate readings, although their impact is generally less severe than dark colors. The chemical composition and pigment density of the polish directly affect the degree of light absorption and scattering.
Visual Assessment and Hygiene Requirements
Beyond electronic monitoring, the natural nail bed provides medical personnel with insight into a patient’s circulatory health. Anesthesiologists and nurses routinely check the tissue color beneath the nail as a quick assessment of oxygenation and perfusion. A bluish discoloration of the nail beds, known as cyanosis, is a noticeable sign of low oxygen levels in the blood.
The surgical team also uses the nail bed to perform a capillary refill time (CRT) test, which assesses peripheral circulation. This test involves pressing on the nail bed until it briefly turns white, or blanches, and then timing how long it takes for the normal pink color to return. A refill time longer than two seconds can indicate poor blood flow or low blood pressure, signaling the need for immediate intervention.
Artificial nails, gel polish, and chipped lacquer present a separate concern related to infection control in the sterile operating room environment. These coatings can harbor bacteria, including pathogens like Staphylococcus aureus or Pseudomonas species, in the microscopic spaces between the nail and the coating. The presence of these microorganisms increases the risk of surgical site infections, especially for patients who may be immunocompromised or undergoing procedures near the extremities.