Noninvasive monitors are finding increased use in the intensive care unit both as labor-saving tools and as a means to reduce complications associated with invasive techniques. The current technology allows for the replacement of a number of invasive devices with a noninvasive counterpart capable of providing similar information. The potential reduction in morbidity and mortality realized with a greater reliance on noninvasive monitors should result in widespread application of these modalities.
Flynn, C. J. (1972). Noninvasive monitoring. Anesthesiology, 37(3), 265–267. https://doi.org/10.1097/00000542-197209000-00001