Application of a micro-computer for the measurement of intracranial pressure and automatic data processing: development of a new system and its application

Abstract

Detailed monitoring of the intracranial pressure and other parameters of patients with intracranial lesions is essential for the recognition of its pathophysiology and for determination of adequate treatment. Recent advances in microcomputer technology has made it possible to assemble a compact intelligent system for bedside use. A new computerized system was developed for the numerical analysis of intracranial pressure (ICP), systemic blood pressure (BP), and heart rate (HR). ICP and BP were detected by pressure transducers and HR by ECG equipment. The systolic, mean, and diastolic pressures of ICP and BP were electrically measured. These seven kinds of data were converted to binary code by an analog-to-digital converter and were put into the microcomputer. The data were displayed on a TV monitor and refurnished every two seconds. They were recorded on paper tape and stored in the memory of the microcomputer. Data analysis was divided into the on-line and off-line modes. On-line processing was performed during data acquisition. It made a table of the average and standard deviations of each type of data during the previous hour, and a graph of the mean hourly ICP for the six hours prior with the formula of its regression line. The regression coefficient showed the tendency of the course of the ICP; that is, either increasing, decreasing, or stationary. Off-line processing was performed from the data recorded on the paper tape and included seven kinds of analysis. It coulds: 1) list all seven kinds of data; 2) list the ηHB (the ratio of the ICP pulse pressure to the BP); 3) list the cerebral perfusion pressure; 4) graph the ICP and BP; 5) graph the ICP and BP after smoothing by a moving average; 6) classify the data and; 7) make an ICP histogram. For an accurate analysis of ICP, quantitative analysis is essential. This system is capable of processing a variety of parameters, such as ICP, BP, and H R into digital form, and could also perform multiple data analysis. The program was designed to automatically perform many kinds of processing within a short time. It was also possible to select the most appropriate type of analysis for a given case.