Tidal Volume Measurements in Newborns Using Respiratory Inductive Plethysmography

Abstract

Respiratory inductive plethysmography (RIP) is a well-accepted noninvasive technology for monitoring breathing patterns in adults. Prior attempts to calibrate this device in babies have been fraught with technical difficulties, thereby limiting applications in this population. Recently, a new method, qualitative diagnostic calibration (QDC), has been shown to provide accurate calibration of tidal volume in adults. The QDC method is based upon principles of the isovolume maneuver and carried out during natural breathing without specialized respiratory maneuvers or postural changes. We calibrated RIP with QDC in the supine posture and compared tidal volume (VT) measured with RIP to VT by a face mask-pneumotachograph (PNT) in 21 healthy full-term newborns in supine and prone postures. Eleven of the babies were calibrated during active sleep and 10 in quiet sleep. The mean VT in the supine and prone postures were 19 and 25 ml, respectively. In the supine and prone postures, weighted mean difference between RIP (VT) and PNT (VT) and 95% confidence intervals were -0.05 ml (-0.27, 0.18) and -0.32 ml (-0.08, 0.55), respectively. There was no difference in the accuracy of RIP relative to PNT calibrated during active sleep when thoracoabdominal incoordination was present or quiet sleep when it was not in either the supine or the prone postures. Therefore, in full-term infants, RIP calibrated with QDC solely in the supine posture provides clinically acceptable measurements of VT in both supine and prone postures.

Pletismografia respiratória por indutância: estudo comparativo entre calibração por manobra de isovolume e calibração qualitativa diagnóstica em voluntários saudáveis avaliados em diferentes posturas

“…In contrast, Adams et al (14) reported obtaining satisfactory K values when QDC was performed in neonates. However, the authors did not evaluate the relative contribution of the thoracic and abdominal compartments or the accuracy of the K values obtained.…”

“…(11) According to the authors, the contributions of the rib cages and abdomens of anesthetized children were insufficient to derive K. One of the findings of the present study was the contribution of the rib the gold standard method (ISOCAL), various studies have suggested the use of the QDC method. (11)(12)(13)(14) One of the major advantages of the QDC method is that it is easy to perform, given that, for QDC, individuals need only maintain baseline breathing for 5 min, and calibration is performed on the basis of the variation in the results obtained for each compartment. This method is questionable in view of the RIP calibration principle, i.e., variation in calibration because of volume shifts between the rib cage and abdomen.…”

Proportional Assist Ventilation Decreases Thoracoabdominal Asynchrony and Chest Wall Distortion in Preterm Infants

“…The bands provide voltage changes that are proportional to the changes in their cross-sectional area and thus reflect the volume changes in the rib cage and abdominal compartments. Calibration was achieved by the built-in qualitative diagnostic calibration procedure that determines the relative electrical gains for the two signals (20,21). This procedure takes approximately 5 min and was done while the infants were in the supine position, lying quietly in their incubators.…”

Inductance Plethysmography: An Alternative Signal to Servocontrol the Airway Pressure during Proportional Assist Ventilation in Small Animals

“…The position of the bands was secured with tape. We started the Respigraph and used its built-in qualitative diagnostic calibration procedure to set the relative electrical gains of the rib cage and abdominal transducers (9,12). The protocol was then commenced for the study on normal animals.…”