May 16, 2013
(NASDAQ: MASI) announced today that a new study to be published in the
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%).
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.
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.
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 (
= 0.0056) and precision (
= 0.0024) for respiration rate as compared with capnometry" and "trended a higher sensitivity (
= 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…."
The study concluded that, relative to capnometry, acoustic respiration rate (RRa) "demonstrated greater accuracy, precision, and sensitivity to pauses in ventilation."