Assessment of a New Piezoelectric Transducer Sensor for Noninvasive Cardiorespiratory Monitoring of Newborn Infants in the NICU

Abstract

Background: Electrocardiogram (ECG) and impedance pneumography (IPG), the most widely used techniques for cardiorespiratory monitoring in the neonatal intensive care unit (NICU), have the disadvantage of causing skin damage when used for very premature newborn infants. To prevent skin damage, we designed a new piezoelectric transducer (PZT) sensor. Objective: To assess the potential of the PZT sensor for cardiorespiratory monitoring in the NICU. Methods: The PZT sensor was placed under a folded towel under a neonate to detect an acoustic cardiorespiratory signal, from which heart rate (HR) and breathing rate (BR) were calculated, together with simultaneous ECG/IPG recording for 1–9 days for long and brief (1-min) assessment. Results: The brief assessment showed average correlation coefficients of 0.92 ± 0.12 and 0.95 ± 0.02 between instantaneous HRs/BRs detected by the PZT sensor and ECG/IPG in 27 and 11 neonates examined. During the long assessment, the HR detection rate by the PZT sensor was ∼10% lower than that by ECG (82.6 ± 12.9 vs. 91.8 ± 4.1%; p = 0.001, n = 27), although comparable (90.3 ± 4.1 vs. 92.5 ± 3.4%, p = 0.081) in ∼70% (18/27) of neonates examined; BR detection rate was comparable between the PZT sensor and IPG during relatively stable signal conditions (95.9 ± 4.0 vs. 95.3 ± 3.5%; p = 0.38, n = 11). The PZT sensor caused neither skin damage nor body movement increase in all neonates examined. Conclusion: The PZT sensor is noninvasive and does not cause skin irritation, and we believe it does provide a reliable, accurate cardiorespiratory monitoring tool for use in the NICU, although the issue of mechanical-ventilation noise remains to be solved.

Apnea during Cheyne-Stokes-like breathing detected by a piezoelectric sensor for screening of sleep disordered breathing

“…The detection ratio was higher than expected considering the small dimensions of the piezoelectric sensor. Moreover, no patient complained about the use of the piezoelectric sensor during measurement, consistent with a previous study …”

“…Hence, a simple device such as single‐signal screening instrument has been desired . We have developed a piezoelectric sensor system that is available for cardiorespiratory monitoring and that uses a single piezoelectric‐sensor signal . The piezoelectric sensor captures vibrations produced by heartbeats and breathing movements and noninvasively converts them into an electrical signal; the sensor never comes into contact with the patient's skin because it is placed under a sheet on a bed.…”

Noninvasive Monitoring of Cardiac Preload and Contractility by Heart Beat-Derived Mechanical Vibration on the Chest Wall in Guinea Pigs

“…[5][6][7] The piezoelectric transducer that is part of the accelerometer is useful for detecting cardiac and/or breathing movements when the sensor is placed under the body of small animals or humans. [8][9][10][11] The measurement is achieved by simply placing animals on the piezoelectric sensor and using an ideal high-pass filter to isolate heart sounds from the raw piezoelectric sensor signals. 8,10,11 The signals contain mechanical vibration signals arising from the heart beat, i.e., contraction and relaxation of ventricles, blood ejection, and closing and opening of valves.…”

Neonatal Respiratory Rate Monitoring Using a Pressure-Sensitive Mat

“…Patients admitted to Neonatal Intensive Care Units (NICU) require continuous monitoring of physiological parameters such as Respiration Rate (RR) and Heart Rate (HR). Widely used Respiration Rate (RR) monitoring techniques in NICU include Impedance Pneumography (IP) and flow measurement from mechanical ventilation [1], [2]. These invasive techniques are reliable and well-studied [3]- [5].…”

“…Pressure-and force-based vital signs monitoring has been an active research area for several years, mainly due to the unobtrusive and non-contact nature of the sensors [1], [17], [18], [23], [24], [37][38] [39].…”