Detection of respiratory activity in newborn infants using a noncontact vision-based monitor.

ABSTRACT

OBJECTIVE: To examine the effectiveness of a noncontact vision-based infrared respiratory monitor (IRM) in the detection of authentic respiratory motion in newborn infants. STUDY DESIGN: Observational study in a neonatal intensive care unit. METHODS: Eligible infants lay supine with torso exposed under the IRM's infrared depth-map camera and torso images were recorded at 30 frames/s. Respiratory motion waveforms were subsequently derived from upper (IRMupper ) and lower (IRMlower ) torso region images and compared with contemporaneous impedance pneumography (IP) and capsule pneumography (CP). Waveforms, in 15 s investigative epochs, were scanned with an 8 s sliding window for authentic respiratory waveform (spectral purity index [SPI] ≥ 0.75, minimum five complete breaths). Maximum SPI and frequency of occurrence of authentic respiratory waveform in 15 s epochs were compared between monitoring modalities in pooled and per patient data (Friedman ANOVA). RESULTS: Recordings comprised 532 min of images from 35 infants, yielding 2131 investigative epochs, with authentic respiratory motion detected in all infants. For CP, IP, IRMupper , and IRMlower , the proportion of epochs containing authentic respiratory motion in pooled data were 65%, 50%, 36%, and 48%, with median SPImax of 0.79, 0.75, 0.70, and 0.74, respectively. Per-patient average SPImax was 0.79, 0.75, 0.69, and 0.74 for CP, IP, IRMupper , and IRMlower with proportion of authentic respiratory motion being 64%, 50%, 29%, and 49%, respectively. CONCLUSION: An IRM focused on the lower torso detected authentic respiratory motion with comparable performance to IP in newborn infants in intensive care and deserves further investigation.