Data will be collected on patients in the intensive care units at the selected hospitals on patients who have been assigned, by the attending physician, to have regular pupillary assessments, and in whom staff nurses are performing pupillary assessments with the pupillometer. While a sample size estimate would be considered inappropriate for registry development, power analysis techniques were used to examine the potential of this registry to generate adequate information to begin to fully describe normative data for pupillary exams. Using the assumption that the desire is to understand neurological pupil index (NPi) and size differences within 0.1, and that the spread of data would be approximately normally distributed, a minimum of 3,250 observations is required (alpha = 0.05, beta = 0.80). It must, however, be repeated that this is simply a rough estimate. The registry data generated will, in fact, be the source of data from which future studies will be powered.
