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Accurate long-term pulse oximetry monitoring with greater patient comfort, lower cost and application beyond the ICU

Image courtesy Xhale Assurance

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.


(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

Antimicrobial Research Collaborative (ARC) recommends CRE screening as a priority for admissions to high-risk specialities

Image: ©nata-lunata/Shutterstock #220986358

The Gram-negative bacterial family of Enterobacteriaceae, includes the species Klebsiella, Enterobacter, and Escherichia. These bacteria can cause opportunistic wound infections, gastroenteritis, pneumonia and septicaemia, particularly in hospital patients, including post-operative patients. Carbapenem-resistant Enterobacteriaceae (CRE) is now a serious concern for the NHS (1).

In 2009, reports first emerged from the USA that these new hospital-acquired, antibiotic-resistant bacteria, had caused death in hospital patients. A prediction was made at this time that CRE could be even harder to eradicate than methicillin-resistant Staphylococcus aureus (MRSA) or antibiotic-resistant Clostridium difficile.

Following reports of cases of CRE in more than a dozen hospitals in England and Scotland in 2009, the then Health Protection Agency (HPA) (now Public Health England) issued a warning about what it called, ‘a notable public health risk’(1). Initially, CRE was thought to be imported from patients having had surgery in India and CRE was considered to be a consequence of the increasing number of UK patients travelling abroad for surgery each year (> 100,000 in 2013) (2).

In 2015, a joint collaboration between Imperial College Healthcare NHS Trust, Imperial College Academic Health Sciences Centre (AHSC) and Imperial College London has created a new multidisciplinary research group, the Antimicrobial Research Collaborative (ARC) (3,4). The aim of the ARC is to translate research findings into new infection prevention strategies. This initiative will have an important role in addressing the problem of antimicrobial resistance (AMR).

As part of the ARC collaboration, in April 2015 researchers lead by Professor Alison Holmes, Director of the National Institute for Health Research (NIHR) Health Protection Research Unit (HPRU), Imperial College London, published their review of current CRE screening strategies in the Journal of Infection(5,6). Among the findings of this study, they noted that admissions to high-risk specialties were likely to have higher CRE prevalence rates and that the higher prevalence of CRE resulted in higher detection rates and lower false-positivity rates (6). These researchers have recommended that CRE screening should be prioritised for hospital admissions to high-risk specialties (6).

The CRE strains are resistant to all the standard antibiotics now used in the NHS. Furthermore, some of these resistant bacteria have been shown to survive in hospital environments, such as table surfaces and door handles.

In May 2015, a publication by Weber and colleagues in the US, in the journal Infection Control & Hospital Epidemiology (ICHE) (published online in Feb 2015), reported that CRE-infected patients contaminated the environmental surfaces of hospital rooms in 8.4% of cases, but at low levels (7). Three species of CRE, Enterobacter, Klebsiella, and Escherichia, survived poorly, with 15% survival after 24 hours and 0% survival after 72 hours (7).

The survival of enteric organisms, such as CRE, is likely to be less than the survival of MRSA on hospital surfaces, due to differences in the structure of the bacterial cell capsule. The ICHE study shows that the levels of contamination and survival are high enough to be important in terms of CRE transmission (7).

In conclusion, carbapenem-resistant Enterobacteriaceae (CRE) are an important group of infections for the new multidisciplinary antimicrobial resistance (AMR) teams to target. Despite their reported limited growth and survival on hospital surfaces, the increasing number of reported cases supports the view that now is not the time to be complacent about hospital infection control.

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.


(1) Public Health England. https://www.gov.uk/government/organisations/public-health-england Accessed June 16, 2015

(2) Office for National Statistics, Travel Tends 2013. http://www.ons.gov.uk/ons/dcp171776_361237.pdf Accessed June 16, 2015

(3) Imperial College Healthcare NHS Trust. http://www.imperial.nhs.uk Accessed June 16, 2015

(4) The Antimicrobial Research Collaborative (ARC), Imperial College, London. http://www.imperial.ac.uk/arc Accessed June 16, 2015

(5) The National Institute for Health Research Health Protection Research Unit (NIHR HPRU) in Healthcare Associated Infections and Antimicrobial Resistance, Imperial College London. http://www1.imperial.ac.uk/hpruantimicrobialresistance/ Accessed June 16, 2015

(6) Venanzio V, Gharbi M, Moore LS, Robotham J, Davies F, Brannigan E, Galletly T, Holmes AH. Screening suspected cases for carbapenemase-producing Enterobacteriaceae, inclusion criteria and demand. J Inf 2015;pii:S0163-4453(15)00197-8. http://www.ncbi.nlm.nih.gov/pubmed/26070742 Accessed June 16, 2015

(7) Weber DJ, Rutala WA, Kanamori H, Gergen MF, Sickbert-Bennett EE. Carbapenem-resistant Enterobacteriaceae: frequency of hospital room contamination and survival on various inoculated surfaces. Infect Control Hosp Epidemiol. 2015;36(5):590-3. http://www.ncbi.nlm.nih.gov/pubmed/25661968 Accessed June 16, 2015


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