A Self-Centering Respiration Monitor for Small Animal Research

It is necessary to monitor the physiological state of small animals being maintained under anesthetic. One parameter that may be observed is the respiratory pattern which is particularly important when using anesthetics known to depress respiratory function. A respiration monitor is described which indicates nasal air flow and which has a self-centering feature to eliminate drift. This feature enables the sensitivity of the unit to be increased to allow monitoring from animals with very low tidal volumes. The monitor is small and is battery operated to eliminate line frequency interference of sensitive recording equipment. It gives a meter indication of the respiratory pattern and provides an output suitable for driving a recorder. An audible tone is sounded at each inspiration.