Fig. (8) The Masimo system for acoustic respiratory rate monitoring is a well-established technique for respiratory monitoring. Two forms of available acoustic sensors are available, and both are designed for placement on the neck, near the trachea. The system also includes a pulse oximetry feature, and numerically displays the arterial oxygen saturation, the heart rate and the respiratory rate (known as RRa). Also displayed is the time-domain acoustic waveform, a feature that can be helpful when troubleshooting. While multiple studies have confirmed the value of this method of acoustical respiratory monitoring in a number of settings, the technology as currently available has some important limitations. First, neither the raw nor the processed acoustic signal is available to the clinician to listen to, although the time-domain signal is displayed. The fact that the system does not provide an analog signal output for such purposes also limits the kind of supplementary analysis that might otherwise be performed, such as digitally recording the obtained signals, subjecting the signal to analog or digital filtering, or carrying out real-time color spectrographic analysis of the obtained breath sounds. Also, because of the proprietary nature of the Masimo acoustic monitoring system, little is publicly known about the flat acoustic sensor used. The likelihood, however, is that their sensor is based on piezoelectric film technology, as this technology has proven to be very useful in a variety of clinical applications. Image Credit: us.pdf