Figure 2 illustrates the electronically collected oxygen saturation data compared to the single nurse recorded value for hour 13. Similarly, Figures 3 and 4 compare the single nurse recorded value of oxygen saturation to the electronic data for hours 14, and 17, respectively. The box represents the nurse observation. The box is placed at the beginning of the hour, although there is no way to know at what time during the hour the nurse made the observation. 17 Auto-correlation is a mathematical measurement of the degree to which an observation is influenced by the prior observation.
Clinical homeostasis is the condition when a patient s system is in balance.
Most patients in our study showed various levels of auto-correlation at different times in their oxygen saturation measurements. The researchers believe that this is an issue relative to understanding the meaning of these data. Oxygen saturation is measured to the nearest whole percent. As oxygen saturation approaches 100 percent saturation, the measurement preciseness seems to effect the data behavior. Examination of Figures 2 through 4 leads to only one conclusion, that a single sample per hour is not an adequate representation of the patient's vital signs during throughout the hour.