: Acoustic ventilatory monitoring using a Masimo Pulse CO-Oximeter™ can accurately measure respiratory rate. (Image source: Thinkstock)
Acoustic ventilatory monitoring using a Masimo Pulse CO-Oximeter™ can accurately measure respiratory rate. (Image source: Thinkstock)

Though not an American Society of Anesthesiologists standard, continuous electronic monitoring of ventilatory rate is important. How well does the Masimo Pulse CO-Oximeter (Masimo Corporation, Irvine, CA) with respiratory acoustic monitoring technology (Masimo RRa™) measure respiratory rate? Drs. Joshua H. Atkins and Jeff E. Mandel, both from the Department of Anesthesiology and Critical Care, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, used this monitor to establish the accuracy of respiratory rate determination in 50 patients with a laryngeal mask airway undergoing urologic surgery. The results of this study are discussed in the article titled “Performance of Masimo Rainbow Acoustic Monitoring for Tracking Changing Respiratory Rates Under Laryngeal Mask Airway General Anesthesia for Surgical Procedures in the Operating Room: A Prospective Observational Study,” which was published in the current issue of Anesthesia & Analgesia.

The authors compared the performance of acoustic monitoring to ventilation measured with a pneumotachograph, considered a gold-standard technique. The authors identified 136 transitions in respiratory rate of at least 4 breaths per minute. Respiratory rate changes detected with acoustic monitoring were delayed by 45 seconds from instantaneous rate estimates obtained from the pneumotachograph, a sufficient time for adequate patient care in the majority of situations. Actual respiratory rates were in close agreement. Though erroneous values at times were present during transient apnea, the errors in most instances were present for no more than 30 sec.

Compared to a pneumotachograph, the Masimo using respiratory acoustic monitoring technology accurately measured respiratory rate over a wide range of respiratory rates, from low values due, for example, to opioid-induced respiratory depression, to high rates due to sepsis.

As Dr. Scott D. Kelley, Chief Medical Officer, Respiratory & Monitoring Solutions, Covidien (a competitor of Masimo) and Dr. Michael A. E. Ramsay, Department of Anesthesiology and Pain Management, Baylor University Medical Center, Dallas, Texas note in the accompanying editorial, “Respiratory Rate Monitoring: Characterizing Performance for Emerging Technologies,” “…given the current lack of respiration rate monitoring on the general care floor, it is likely that the available devices are sufficiently accurate for implementation into continuous monitoring care strategies. The critical evidence needed is to assess if the addition of continuous respiration rate monitoring can further enhance patient safety and outcomes when utilized. Given the clear role of respiration rate as the “vital” vital sign, this evidence will likely be provided in the near future.”