Non-invasive physiological measurements

The author points out noninvasive measurements are highly desirable in physiology for two main reasons: (1) absence of interference with the system under evaluation and (2) safety for the subject. Such measurements are especially important in children and during sleep or exercise studies. In these conditions a simple mouth piece, for instance, significantly modifies breathing pattern and can be considered as invasive. Inexpensive, powerful computer technology has greatly improved the availability and quality of noninvasive equipment. The author argues, however, that criteria such as accuracy, specificity, reliability, simplicity and ruggedness must be met before using noninvasive measurements are used for diagnosis and prognosis in the management of patients.>