Pulse oximetry is useful for monitoring and assessing several patient parameters. As a standard of care, it provides you with noninvasive indication of patients’ cardiopulmonary status. However, pulse oximetry does have limitations.
In this blog post, we identify common problems with pulse oximetry use such as:
- Patient and environment conditions can make monitoring difficult
- Nurses are often burdened by alarm fatigue
- Pulse oximetry doesn’t measure everything
We hope to provide solutions to these limitations that help you provide the best care for your patients.
Patient and area conditions can make monitoring difficult
Several factors can interfere with the correct function of a pulse oximeter – depending on your facility’s pulse oximetry technology – including1:
- Light. Bright light (such as the operating theater light or sunlight) directly on the sensor may affect the reading. To prevent this, shield the sensor from direct light.
- Motion. Movement may make it difficult for the sensor to pick up or maintain a signal.
- Pulse volume. The oximeter only detects pulsatile flow. It may be unable to detect a pulse when cardiac output or blood pressure is low due to hypovolemic shock. It may also fail to detect a signal when the patient has an arrhythmia.
- Vasoconstriction reduces blood flow to the peripheries. The oximeter may fail to detect a signal if the patient is very cold and peripherally vasoconstricted.
- Carbon monoxide poisoning may give a falsely high saturation reading. Carbon monoxide binds very well to hemoglobin and displaces oxygen to form a bright red compound called carboxyhemoglobin. This is only an issue in patients that have been exposed to excessive carbon monoxide.
Low perfusion. Low perfusion can make it difficult to accurately read and track the state of true arterial circulation. Low perfusion often leads to inaccurate or absent pulse oximetry measurements.†2
†Oxygen saturation accuracy can be affected by certain environmental, equipment, and patient physiologic conditions that influence readings of SpO2. Please consult the IFU and Operator’s Manual of your pulse oximetry equipment for full safety information.
Nurses are often burdened by alarm fatigue
Alarms alert you to clinical problems such as:
- Low saturation emergency (hypoxia) — i.e. SpO2 below designated threshold
- No pulse detected
- Low pulse rate
- High pulse rate
However, what happens when you are overwhelmed with an additional 350 alarm conditions per patient per day?3 A true life-threatening event may be lost in a cacophony of noise from the multitude of devices with competing alarm signals. These alarms try to capture nurse attention without offering clarity on the action that should be taken. This issue can be compounded by inconsistent alarm system functions, including:4
- Providing information
- Suggesting action
- Directing action
- Taking action
Inconsistent alarm system characteristics — such as information provided, integration, degree of processing, and prioritization — can also add to the problem.4
Smart alarm management technologies are designed to reduce the number of nuisance alarms while alerting caregivers to clinically significant events. Smart alarm technology has been built into both Nellcor™ pulse oximetry with OxiMax™ technology and Microstream™ capnography monitoring platforms.
Nellcor™ SatSeconds alarm management technology is a clinician-controlled feature engineered to differentiate between serious hypoxemia and minor transient events — without the dangers associated with alarm delays. It generates alarms based on both the depth and the duration of a patient’s desaturation, helping reduce nuisance alarms.3,4
For example, with a Nellcor™ SatSeconds alarm setting of 50, an alert would trigger if:†
- A desaturation of five percent below the alarm threshold lasts for 10 seconds (five percent x 10 seconds=50)
- A desaturation of 10 percent below the alarm threshold lasts for five seconds (10 percent x five seconds=50)
- Data shows that Nellcor™ SatSeconds alarm management technology helps reduce the number of clinically insignificant alarms. This gives clinicians the opportunity to respond to alarms that are clinically relevant.4
†A third party study showed that at a setting of 50, nuisance alarms were reduced in the neonate population by 40%. Clinical judgment should be used to determine appropriate SatSeconds settings.
Related: Learn more about our complimentary education, dedicated product specialists, collaboration opportunities, professional U.S.-based technical help, and Nellcor™ pulse oximetry monitoring system warranties.
Pulse oximetry doesn’t measure everything
A pulse oximeter doesn’t provide information about respiratory rate, tidal volume, cardiac output, or blood pressure.
Hemoglobin may remain saturated with oxygen despite hypoventilation causing rising levels of carbon dioxide.5 In addition, oxygen saturation may not fall below 90 percent until the patient is already in serious trouble, especially if the patient is on supplemental oxygen.5 In fact, normal oxygenation saturation doesn’t rule out respiratory compromise — respiratory insufficiency, failure, and arrest — which is a threat to patients and health systems.6 A 2016 analysis of 44,551 acute respiratory events revealed a mortality rate of 39.4 percent.6
To identify respiratory compromise in its early stages, you should consider leveraging continuous patient monitoring of both oxygenation and ventilation. Continuous monitoring of etCO2 and SpO2, paired with a clinical remote monitoring system, may help improve patient safety.7–11 It may also help your hospital avoid a cost of around $53,502 per respiratory failure episode, according to a HealthGrades estimate.12
Related: Learn how continuous patient monitoring systems such as our Vital SyncTM remote patient monitoring and clinical support solution lets you see what’s happening at a patient’s bedside without having to be in the room.
1. World Health Organization. The WHO Pulse Oximetry Training Manual. World Health Organization Website. https://www.who.int/patientsafety/safesurgery/pulse_oximetry/who_ps_pulse_oxymetry_training_manual_en.pdf. Published 2011.
2. Gehring H, Hornberger C, Matz H, et al. The effects of motion artifact and low perfusion on the performance of a new generation of pulse oximeters in volunteers undergoing hypoxemia. Respir Care. 2002; 47:48–60.
3. Brostowicz HM, Khodayar Rais-Bahrami K. Oxygen saturation monitoring in the neonatal intensive care unit: evaluation of a new alarm management. Presented at: Program and abstracts of the American Academy of Pediatrics National Conference & Exhibition. Washington, D.C. October 17–20, 2009.
4. Stefanescu BM et al. Improving Filtering of Pulse Oximeter Monitoring Alarms in the Neonatal ICU: Bedside Significance. Resp Care. 2016 (Vol 61 No 1): 85-89.
5. Kirkland L. Pulse oximeter a valuable tool, but has limitations. ACP Hospitalist Website. Dec. 2009.
6. Andersen LW, Berg KM, Chase M., et al. Acute respiratory compromise on inpatient wards in the United States: Incidence, outcomes, and factors associated with in-hospital mortality. Resuscitation. 2016;105:123–129.
7. Metzner J, Posner KL, Domino KB. The risk and safety of anesthesia at remote locations: the US closed claims analysis. Curr Opin Anaesthesiol. 2009;22(4):502–508.
8. Cook TM, Woodall N, Harper J, Benger J. Fourth National Audit Project. Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Part 2: intensive care and emergency departments. Br J Anaesth. 2011;106(5):632–642.
9. Patail B. Lead-user Profile: The Veterans Health Administration. In: Infusing Patients Safely: Priority Issues from the AAMI/FDA Infusion Device Summit. Oct. 5, 2010:12.
10. McCarter T, Shaik Z, Scarfo K, Thompson LJ. Capnography monitoring enhances safety of postoperative patient-controlled analgesia. Am Health Drug Benefits. 2008;1(5):28–35.
11. Jopling M, Heard L, Kofol T, Warner E. Evaluating the cost-effectiveness of capnography monitoring in procedural sedation: a gastroenterology (GI) suite cost-avoidance model. Gastrointest Endosc. 2015;81(5S):AB193.
12. Health Grades Patient Safety in American Hospitals Study. http://patientsafetymovement.org/wp-content/uploads/2016/02/Resources_Reports_Patient_Safety_in_American_Hospitals_Study.pdf. March 2011
© 2020 Medtronic. All rights reserved. Medtronic, Medtronic logo and Further, Together are trademarks of Medtronic. All other brands are trademarks of a Medtronic company. 05/2020-20-PM-0021
About the AuthorMore Content by Clarerita Higgins