Breathing patterns in lambs after oleic acid lung injury utilizing respiratory inductive plethysmography

We measured breathing patterns utilizing a respiratory inductive plethysmograph (RIP) in seven healthy nonsedated lambs after an iv infusion of oleic acid (50 mg/kg) to induce acute pulmonary edema. Our single position graphic (SPG) calibration technique was employed for gain factor calculation. Accuracy was validated by the simultaneous volume measurement of RIP and integrated pneumotachography (PNT). Of a total 840 validation breaths, 467 (56%) were within 5% of PNT, 734 (87%) were within 10%, and 834 (99.9%) were within 20%. In each study baseline physiologic and breathing pattern data were collected and also at 15, 30, 60, 90, 150, and 210 min postoleic acid infusion. Validation of RIP accuracy before each data collection revealed 29% required new gain factor calculation. Recalibration was done within 5 min. Excluding respiratory frequency, which remained at 30% above baseline, variables were not significantly different than baseline measurements at the 210-min interval. Results suggest that calibration of RIP using our SPG technique is a time-efficient method and that RIP can accurately measure breathing patterns, providing an additional tool for assessment of experimental lung injury in lambs.