Assessment of a new piezoelectric transducer sensor for noninvasive cardiorespiratory monitoring of newborn infants in the NICU.
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 approximately 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 approximately 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.


CONCLUSIONS
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.
Department of Cell Physiology, Akita University Graduate School of Medicine, Akita, Japan. bigwave@gipc.akita-u.ac.jp
Shinichi
S
Sato
Wako
W
Ishida-Nakajima
Akira
A
Ishida
Masanari
M
Kawamura
Shinobu
S
Miura
Kyoichi
K
Ono
Nobuya
N
Inagaki
Goro
G
Takada
Tsutomu
T
Takahashi
D015374:Biosensing Techniques / Q000295:instrumentation*; D002319:Cardiovascular System / Q000503:physiopathology*; D004562:Electrocardiography / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D005260:Female; D005865:Gestational Age; D006339:Heart Rate; D006347:Heart Sounds; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008838:Microcomputers; D008991:Monitoring, Physiologic / Q000295:instrumentation* / Q000379:methods; D015656:Respiratory Mechanics / Q000502:physiology*; D014159:Transducers