Respiratory Monitoring: Advantages of Inductive Plethysmography over Impedance Pneumography

Inductive plethysmography and impedance pneumography are two non-invasive technologies for measuring respiratory function. The following report describes the advantages of inductive plethysmography, which include greater accuracy and sensitivity; the ability to assess thoracoabdominal coordination; and the minimization of motion artifact. Together, these properties make inductive plethysmography a superior technique for identifying and differentiating obstructive, central and mixed sleep apneas, and for detecting hypopneas. INTRODUCTION The ability to accurately monitor respiratory function is critical to the study of such disorders as sleep apnea and chronic obstructive pulmonary disease, where respiratory dysfunction can be dangerous and even fatal. In addition, certain medications can affect respiration and monitoring these effects can be useful to the clinical researcher. Respiratory monitoring can also provide insight into such conditions as anxiety disorder, where respiratory instability has been documented even independent of panic attacks. Impedance pneumography and inductive plethysmography are two noninvasive technologies available for measuring respiratory function. Impedance pneumography has been available for decades and is commonly used in clinical research. However, the technology has limitations that can affect the accuracy and application of this method. Inductive plethysmography is a newer alternative to impedance pneumography that is associated with a higher degree of accuracy and has additional practical benefits to the clinical researcher. IMPEDANCE PNEUMOGRAPHY Impedance pneumography employs low amplitude, high frequency (50 to 500 kHz) alternating current (AC) between two surface electrodes to record thoracic movements or volume changes at the rib cage (RC) during a respiratory cycle. Based on Ohm’s