Calibration of respiratory inductive plethysmography in lambs receiving intermittent mandatory mechanical ventilation

Respiratory inductive plethysmography (RIP) is a noninvasive method of assessing breathing pattern. We employed a single-position graphic (SPG) calibration technique for gain factor calculation in 38 studies on five sedated lambs who were receiving intermittent mandatory mechanical ventilation (IMV). The SPG technique uses selection of two breaths from a 20-sec run of breaths with different ribcage/pneumotachograph (PNT) and abdomen/PNT ratios for gain calculation. Validation of gains was performed by comparing volumes obtained simultaneously by RIP and PNT. The mean tidal volume (VT) measured by RIP corresponded well with mean VT measured by PNT with animals receiving 42.2 +/- 13.2 (SD) % of breaths over 1 min by IMV. Time for calibration and validation ranged between 15 and 30 min. The results of this study suggest that the SPG calibration technique provides an accurate method of calibration of RIP in sedated lambs receiving IMV.