FDA Approval of the Nasal Alar SpO₂ Sensor

On the 18th of March 2015, Xhale Assurance, developer of the patented Assurance® Nasal Alar SpO₂™ Sensor, announced its approval by the US Food and Drug Administration (FDA) and the global launch of this second-generation pulse oximetry sensor (1,2). The new Xhale Assurance® Nasal AlarSpO₂™ Sensor is compatible with the majority of pulse oximetry monitors used in many different healthcare settings. Pentland Medical is now marketing this product as the Nasal Alar SpO₂ Sensor (3).

Oxygen Supplementation in Patient Treatment

Acute and chronic medical conditions can be associated with hypoxia and require supplemental oxygen therapy. The acute medical conditions include attacks of asthma, pneumonia or respiratory distress syndrome (RDS). In premature babies, oxygen supplementation is given for the condition of bronchopulmonary dysplasia (BPD).

The chronic conditions requiring oxygen supplementation include chronic obstructive pulmonary disease (COPD), heart failure and sleep apnoea. In the treatment of these conditions, oxygen is usually administered through a nasal continuous positive airway pressure (NCPAP) machine, a nasal tube or a ventilator.

Pulse Oximetry in the Evaluation of Blood Oxygenation

It is important to monitor the requirements for and effects of oxygen supplementation as too much oxygen can be as harmful as too little. Pulse oximetry is a non-invasive method used to measure the oxygen level (or oxygen saturation) in the blood of the peripheral tissues, usually using a sensor attached to the finger.

The technology is based on detection of the light absorptive characteristics of oxygenated haemoglobin and the pulsating properties of the blood flow in the peripheral arteries and arterioles. With each heartbeat, there is a small increase in vascular volume, with an associated increase in oxygen-rich haemoglobin.

The pulse oximeter consists of a clip-like sensor that houses a light source, a light detector, and a microprocessor. One side of the sensor contains an infrared and a red light source which are transmitted through the tissues to the light detector on the other side. The oxygen-rich haemoglobin absorbs more of the infrared light; oxygen-poor hemoglobin absorbs more of the red light. The microprocessor calculates these differences and converts the information to a digital readout of the amount of oxygen being carried in the blood. This information enables the attending physician or nurse to evaluate the need for supplemental oxygen.

Use and Advantages of the Nasal Alar SpO₂ Sensor

The Nasal Alar SpO₂ Sensor fits comfortably on the nasal ala that is lateral to the nostril (nares) and does not require any adhesive to keep it secure (3). The Nasal Alar SpO₂ Sensor can be easily removed and reapplied for use during the patient’s hospital stay (3). The nasal ala is a highly vascular region that is fed anatomically by both the external and internal carotid arteries. This multi-directional arterial supply provides strong, reliable photoplethysmography signals that respond rapidly to changes in the patient’s arterial oxygen saturation. These signals can be lost when using sensors located on the finger (4).

The nasal alar site has the following advantages:

1. This site has no clinically significant sympathetic tone and, therefore, does not lose signal due to the patient being cold, anxious or stressed.
2. This site is less affected when patients experience diminished peripheral perfusion, as in cardiovascular disease, hypovolaemia or following medications that cause vascular changes.
3. The nasal alar site is less subject to signal distortion due to sensor interference from ambient light.
4. The strong signal from this location provides consistent accuracy, even at very low oxygen saturations.
5. The nasal alar site location makes the sensor less likely to be dislodged, which reduces alarms.
6. The nasal alar attachment site is easily accessed by an anaesthetist during surgery; the non-adhesive attachment makes the sensors easy to reposition.

Clinical Evaluation of the Nasal Alar SpO₂ Sensor

Recent studies support the feasibility and accuracy of nasal alar pulse oximetry (5). The many unique features of this nasal alar pulse oximetry sensor have encouraged clinical studies to evaluate its role beyond the operating theatre, in patients with acute, chronic or long-term medical conditions.

In February 2015, the results of a usability and acceptance study for the use of the Nasal Alar SpO₂ Sensor in a non-hospital setting, showed that 50 volunteer subjects were able to wear the sensor for seven days (6). All 50 study participants reported that, when compared to wearing a finger pulse oximeter, the Nasal Alar SpO₂ Sensor was more comfortable and interfered less with daily living activities (6). Although the use of oximeter sensors at sites such as the finger and forehead have been associated with skin pressure complications, there are no reported complications from the use of the Nasal Alar SpO₂ Sensor (6,7).

The benefits of the Nasal Alar SpO₂ Sensor include.

1. Reliable, consistent and accurate oxygen saturation measurement, that is unaffected by reduced peripheral perfusion.
2. Sensitive and rapid detection of changes in oxygen saturation.
3. Ease of access to the alar nasal sensor attachment site, even during surgery.
4. Comfort when wearing the sensor for long periods of time, with no complications.
5. The nasal alar location of the sensor resists monitoring fluctuations or signal distortion due to ambient light or motion.
6. Cost savings, when compared to finger and forehead sensors.

Cost: Nasal Alar SpO₂ Sensor

The Nasal Alar SpO₂ Sensor costs less than £20 ($30 USD) each (3). Patient studies have shown that the sensors are durable which means a significant cost saving can be expected in longer term monitoring (8). Digital sensors cost £8 ($12 USD), and forehead sensors are up to £16 ($24 USD). In the US, the average stay in ICU is 3.8 days and during this time, digital sensors will require replacement (8).

In conclusion, these results indicate that the Nasal Alar SpO₂ Sensor can be used comfortably, safely, effectively and at relatively low cost, not only in the operating room during anaesthesia or in intensive care, but also in a variety of situations within and outside the hospital.

This report has been received and reviewed by Dr Richard Melker, Xhale Assurance, on 25th June, 2015, prior to online publication.

If you would like to comment on any of the issues raised by this article, particularly from your own experience or insight, Healthcare-Arena would welcome your views.

References

(1) Xhale website. http://xhale.com Accessed June 18, 2015

(2) Press Release. Xhale Assurance Announces FDA Approval of its Second Generation Nasal Alar SpO₂ Sensor. March 18, 2015. http://xhale.com/xhale-assurance-announces-fda-approval-of-its-second-generation-nasal-alar-SpO₂-sensor/ Accessed June 18, 2015

(3) Pentland Medical. Nasal Alar SpO₂ Sensor. Product information. http://www.pentlandmedical.co.uk/index.php/products/pulse-oximetry-sensor/ Accessed June 18, 2015

(4) Davis DP, Aguilar S, Sonnleitner C, Cohen M, Jennings M. Latency and loss of pulse oximetry signal with the use of digital probes during pre-hospital rapid-sequence intubation. Prehosp Emerg Care 2011;15(1):18-22. http://informahealthcare.com/doi/abs/10.3109/10903127.2010.514091 Accessed June 18, 2015

(5) Morey TE, Rice MJ, Vasilopoulos T, Dennis DM, Melker RJ. Feasibility and accuracy of nasal alar pulse oximetry. Br J Anaesth 2014;112(6):1109-14. http://bja.oxfordjournals.org/content/112/6/1109.long Accessed June 18, 2015

(6) Melker, RJ, et al. Usability/Acceptance Study Final Report Xhale Assurance Nasal Alar Sensor. Feb. 2015. Unpublished data. On file, Xhale Assurance.

(7) Lee M, Eisenkraft JB, Forehead pulse oximeter-associated pressure injury. A Case Rep. 2014 Jan 15;2(2):13-5. doi: 10.1097/ACC.0b013e3182a66b29. http://www.ncbi.nlm.nih.gov/pubmed/25611043 Accessed June 18, 2015

(8) Pfuntner A, Wier LM, Steiner C. Costs for Hospital Stays in the United States, 2010. HCUP Statistical Brief #146. January 2013. Agency for Healthcare Research and Quality, Rockville, MD. http://www.hcup-us.ahrq.gov/reports/statbriefs/sb146.pdf. Accessed June 18, 2015