Near Infrared Spectral Determination of Human Tissue pH

A reflectiver near infrared (NIR spectrometer is proposed for the noninvasive measurement of surface and deep tissue pH. Previous experimental studies have demonstrated on a preliminary basis the ability to estimate liquide pH in complex biological matrices based on NIR spectra [Dre 90][Sch 93], and the proposed development program will design, contruct and test an experimental bench NIR pH measurement. Biotronics has also demonstrated on a previous and related Navy-sponsored SBIR program, designated TAMM for Transcutaneous Analyte Measuring Method, tested over 750 patients in Navy and civilian hospitals with a reflective NIR instrument for the measurement of the primary human body electrolytes: sodium, chloride, calcium, potassium and bicarbonate. The physical principle involved in these NIR measurements is the same as for pH - ionic distortions of the primary NIR water spectrum. In fact, pH measurements represent a lesser challenge because of the greater density of the hydrogen ion in human tissue. The bench prototype NIR instrument will be designed to operate in different NIR spectral regions to achieve varying depths of tissue penetration and to explore various spectral regions with a view to future spectral optimization in the Phase II preproduction prototype. The previous successful biotronics TAMM experience with reflective NIR spectrometry and pattern recognition in noninvasive human blood electrolyte measurements bodes well for achieving the objectives of this program. commercialization and military applicatiom of the new NIR pH instrument will follow the same paths now opened as a result of the Navy TAMM SBIR program. Major impacts will be in military combat casualty care and civilian emergency medicine.