Masimo announced today that a new study to be published in the June 2013 edition of the journal Anesthesia & Analgesia (available online today) concludes that Acoustic Respiration Rate (RRa™) shows "significantly greater accuracy and precision for respiratory rate as compared to capnometry." Study results suggest that "the capnometer is about 3% less precise" than RRa (95% confidence interval, 0.9-4.8%).1
Abnormal ventilatory rate is a common clinical occurrence that can precede a major clinical event, such as cardiac arrest, onset of sepsis, and respiratory infection.2,3 Continuous monitoring of respiration rate—a critical ventilatory vital sign that provides early detection of respiratory compromise and patient distress—is especially important for post-surgical patients receiving sedatives, opioids, or patient-controlled analgesia (PCA) for pain management as the sedation can induce respiratory depression and place patients at considerable risk of serious injury or death.4-7
In the published study, 33 (adult) post-surgical patients were monitored in the post-anesthesia care unit using a Masimo Pulse CO-Oximeter with rainbow® Acoustic Monitoring™ technology (Rad-87, version 7804) connected to an adhesive acoustic respiration rate Sensor (RAS-125, rev C) applied to the neck and a nasal cannula connected to a bedside capnometer (Oridion Capnostream20, version 4.5). Both the acoustic monitor and capnometer were connected to a computer for continuous acoustic and expiratory carbon dioxide waveform recordings—enabling automatic calculation of a reference ventilatory rate for each device—while a trained technician simultaneously listened to the breathing sounds from the acoustic signal to determine inspiration and expiration reference markers within the ventilatory cycle. Results after 3,712 total monitoring minutes (average of 112 minutes per subject) showed rainbow® acoustic respiration rate monitoring had "significantly greater accuracy (P = 0.0056) and precision (P = 0.0024) for respiration rate as compared with capnometry" and "trended a higher sensitivity (P = 0.0461)" to pauses in ventilation (81% vs 62%) in 21 apneic events." While reliability of the two devices was high on average, study authors noted that study "results suggest that the capnometer is about 3% less precise…."1
The study concluded that, relative to capnometry, acoustic respiration rate (RRa) "demonstrated greater accuracy, precision, and sensitivity to pauses in ventilation."
According to the study's lead researcher and author, Michael Ramsay , M.D., Chief of the Department of Anesthesiology and Pain Management at Baylor University Medical Center in Dallas, "The results of our study show that the addition of RRa for continuous ventilatory rate monitoring provides a safety net for post-surgical patients receiving opioids with the potential to greatly improve the timeliness of response to an adverse respiratory event. Both of which help to improve patient safety and outcomes for post-surgical patients in recovery areas and on general care floors."
Masimo rainbow® Acoustic Monitoring™ technology noninvasively and continuously measures respiration rate using an innovative adhesive sensor with an integrated acoustic transducer that is easily and comfortably applied to the patient's neck. Using acoustic signal processing that leverages Masimo's patented revolutionary Signal Extraction Technology (SET®), the respiratory signal is separated and processed to display continuous acoustic respiration rate (RRa)—enabling earlier detection of respiratory compromise and patient distress.
As a result of mounting evidence of the increased risk to patients, many nationally recognized health care organizations have launched major initiatives recommending continuous monitoring of oxygenation and ventilation of post-surgical patients to detect and respond appropriately to the early indicators of physiological deterioration, including: the Institute for Healthcare Improvement,8 the Joint Commission,9,10 the Anesthesia Patient Safety Foundation,11 and the American Society of Anesthesiologists.12 Traditional methods for monitoring a patient's respiration rate have demonstrated limitations that can affect accuracy and patient tolerance.13-15
"This study provides a side-by-side analysis of RRa and capnography measurements that compares more than 3,700 monitored minutes of continuous respiration data," said Michael O'Reilly, M.D., Chief Medical Officer of Masimo. "With such detailed data points and critical analysis, the results are undeniable—Masimo rainbow® Acoustic Monitoring™ technology offers improved sensitivity, accuracy, precision and reliability over capnometry for continuous monitoring of ventilation rate in post-surgical patients."
1 Ramsay M, Usman M, Lagow E, Mendoza M, Untalan E, De Vol E. "The Accuracy, Precision and Reliability of Measuring Ventilatory Rate and Detecting Ventilatory Pause by rainbow Acoustic Monitoring and Capnometry." Anesth Analg; April 30, 2013 ANE.0b013e318290c798. Available online here.
2 Schein RM, Hazday N, Pena M, Ruben BH, Sprung CL. "Clinical antecedents to in-hospital cardiopulmonary arrest." Chest 1990;98:1388–92. Available online here.
3 Mailey J, Digiovine B, Baillod D, Gnam G, Jordan J, Rubinfeld I. "Reducing hospital standardized mortality rate with early interventions." J Trauma Nurs 2006;13:178–82. Available online here.
4 Joint Commission on Accreditation of Healthcare Organizations. Sentinel event alert: patient controlled analgesia by proxy; JCAHO. 2004. Available online here.
5 Institute for Safe Medication Practices. Safety issues with patient-controlled analgesia: Part I – How errors occur; ISMP. 2003. Available online here.
6 Institute for Safe Medication Practices. Safety issues with patient-controlled analgesia: Part II – How to prevent errors; ISMP. 2003. Available online here.
7 Bird M. "Acute pain management: a new area of liability for anesthesiologists"; ASA Newsletter. 2007; 71:8. Available online here.
8 Institute for Healthcare Improvement. Rapid Response Teams. Available online here.
9 The Joint Commission. 2009 National Patient Safety Goals. Available online here.
10 The Joint Commission. Sentinel event alert: Safe use of opioids in hospitals; 2012. Available online here.
11 Anesthesia Patient Safety Foundation. APSF Newsletter. "No Patient Shall be Harmed by Opioid-Induced Respiratory Depression." 2011; 26(2):21-40. Available online here.
12 American Society of Anesthesiologists. Practice Guidelines for the Prevention, Detection and Management of Respiratory Depression Associated with Neuraxial Opioid Administration Available online here.
13 Maddox RR, Williams CK, Oglesby H, Butler B, Colclasure B. "Clinical experience with patient-controlled analgesia using continuous respiratory monitoring and a smart infusion system." Am J Health Syst Pharm 2006;63:157–64.
14 Friesen RH, Alswang M. "End-tidal PCO2 monitoring via nasal cannulae in pediatric patients: accuracy and sources of error." J Clin Monit 1996;12:155–9.
15 Gaucher A, Frasca D, Mimoz O, Deboene B. "Accuracy of respiratory rate monitoring by capnometry using the Capnomask in intubated patients receiving supplemental oxygen after surgery." Br. J. Anaesth 2012;108:316–20.