Abstract
The Video Overlay Monitoring System (Here in after referred to as VOLMS), which uses a personal computer to superimpose values from a commercially available monitor onto the intraoperative images and allows the storage and transfer of these images, has already been discussed in Part 2. This system also displays the results of various information processing which uses preoperative values as a reference. With the objective of obtaining possibly the most exact preoperative values, we have developed the following software for determining preoperative values that follows the process of estimating theses values, and installed this software in the VOLMS.
1. A monitoring interval was set to one minute,and the current values of four variables-systolic blood pressure (SBP),mean blood pressure (MBP), pulse rate (PR), and percutancously measured saturation of arterial oxygen (SpO2)- were sequentially compared with their previous values.
2. The logical multiplications of three consecutively measured values for each variable were almost the same values in that environment.
The preoperative values were used as a reference that were obtained by this software during implant placement. These values were often observed throughout the surgery. In the information processing mode of the VOLMS, when the value of any of the variables exceeded an alarm level, the screen automatically switches to check its current value. The preoperative values, the upper and lower limits of an alarm, and a percentage change in the rate pressure product (RPP) from its preoperative value that were displayed on that screen became accurate for the patient. In addition, the advisory marks, which indicated changes from the preoperative values, became more rliable.
