XHALE ASSURANCE® | A Philips Company

Nasal Alar SpO2 Sensor

The next generation of pulse oximetry

Traditional digit-based pulse oximetry presents several challenges to effectively and efficiently monitoring a patient’s parameters. Because of the distance from a patient’s heart to the fingertip or toes, a digit-based pulse oximetry sensor can result in slower detection of saturation changes which can delay critical decision making.

Standard pulse oximeters using sensors on the patient’s digit fail to work in a variety of common clinical conditions that lead to diminished blood flow to the digits, including patient shock (low blood pressure from a variety of causes), patient anxiety, peripheral vascular disease (a disease of blood vessels outside the heart), the advanced age of the patient (the elderly tend to have less blood circulation), abnormally low patient body temperature (including hypothermia), swelling of the digits and the administration of many drugs that decrease peripheral blood flow. In addition, during surgery a patient’s hands are frequently covered or wrapped, providing limited access to the anesthesiologist. The digit placement of the oximetry sensor also often results in the sensors being dislodged, resulting in loss-of-signal alarms.


Our Assurance® technology offers several advantages to existing digit-based oximetry:

  • monitoring a branch of the internal carotid, which provides blood to the brain, at the nasal ala site enables faster detection of oxygen saturation changes, reducing the lag-time between hypoxia in the brain and notification on the oximetry monitor;
  • the nasal ala site location of our sensors has no clinically significant sympathetic tone, and therefore, does not lose signal due to patients being cold, anxious or in stress;
  • monitoring at the nasal ala site is less negatively affected when patients experience diminished peripheral perfusion, reducing loss of signal incidents resulting from cardiovascular disease, hypovolemia or from the administration of vasoactive medications;
  • the nasal ala site is generally not subject to signal distortion due to ambient light interference (which occurs when a bright light, such as a light used during surgery, interferes with a pulse oximetry sensor);
  • the strong signal provided by the nasal ala site provides consistent accuracy, even at very low oxygen saturations;
  • the nasal ala site location of our sensors makes the sensor less likely to be dislodged, reducing loss-of signal alarms;
  • the nasal ala attachment site generally is easily accessed during surgery; and
  • the non-adhesive attachment of our Assurance® sensors makes the sensors easy to reposition and allows use for lengthy procedures or long stays.

The nasal ala, the fleshy part of the nose adjacent to the opening of the nares (nostril), is a region rich in vasculature that offers a unique monitoring site for pulse oximetry.

This site is fed by both the external and internal carotid arteries. The internal carotid provides blood to the brain, and this multi-directional arterial supply provides strong, reliable photoplethysmography signals that are rapidly responsive to changes in the patient’s arterial oxygen saturation.

Unlike the extremities, this measurement site is less susceptible to patient movement and loss of signal due to variations in peripheral perfusion. And it is easily accessed by an anesthesiologist during surgery.


Placement of the Assurance® Nasal Alar SpO2 Sensor is simple, fitting comfortably on the nasal ala. Because secure sensor placement does not depend upon adhesive attachment, the sensor is easily removed and reapplied as necessary for use throughout the length of the patient’s hospital stay.