Oesophageal techniques for deriving the lung dynamics of quietly breathing sheep

An airway monitoring system was developed to record the lung dynamics of sheep using oesophageal pressure techniques. These techniques are minimally invasive and do not impede the animal from breathing spontaneously. This study investigates three methods for deriving lung resistance (R) and compliance (C) by evaluating their ability to select regular breaths amongst artefact effected signals. The Multi Linear Regression method, the Modified Mead-Whittenberger (MMW) method and Isovolumetric method were tested against signals with movement and/or swallowing artifacts. Their coefficient of variation (% CV) revealed that the MMW had the least variation with R at 35% CV and C at 25 % CV. The lung dynamics for 14 quietly breathing sheep were R = 1.5 ± 0.5 cmH2O/l/s, C = 0.20 ± 0.08 l/cmH2O, tidal volume = 0.25 ± 0.05 litres and respiratory rate = 26 ± 6 bpm.