Non-invasive Tidal Volume Monitoring Using the Linshom Respiratory Monitoring Device

Many post-operative complications arise from patients who breathe inadequately. Inadequate respiration, whether the result of surgery or the anesthesia, causes a decrease in blood oxygen saturation and an increase in carbon dioxide partial pressure. Both of these surrogate measurements of respiration may pose a challenge to measure. Some administer exogenous oxygen to all patients as they leave the operating room in order to maintain the blood oxygen saturation. This renders the oximeter a less sensitive metric of depressed respiration. In the face of decreased respiration, the carbon dioxide levels continue to increase slowly and often go undetected unless blood gases are measured. Indeed carbon dioxide blood levels are the only metric to detect inadequate ventilation using this surrogate index. Monitoring ventilation is a serious challenge outside of critical care settings. In fact, there are no monitors available that can measure tidal volume or relative tidal volume outside of these settings. Linshom is a novel instrument that tracks relative respiration by measuring the excursions of the temperature swings between inspiration and expiration and normalizing them to the patient's breathing. This monitor may be the first non-invasive monitor to measure relative tidal volume in non-critical care settings. The purpose of this study is to determine whether a non-invasive, temperature-based respiratory instrument can track tidal volume (Vt) in patients. The investigators hypothesize that the Linshom device can accurately and consistently track tidal volume as measured by closed loop mechanical ventilator.