Microprocessors in intensive care medicine

Three specific applications of microprocessors to intensive care instrumentation are presented. Automatic feedback control of mechanical ventilation is achieved using end-tidal carbon dioxide concentration, oxygen consumption, and carbon dioxide production as the input control parameters. Closed-loop control of fluid infusion is used for resuscitating burn patients; intravenous infusion rate is microprocessor controlled to maintain a desired urine output. Metabolic rate is measured by indirect calorimetry using a microprocessor to compute the results and control the measuring instrumentation. These examples show how microprocessor technology has been used to expand instrumentation capability and implement feedback control. These systems use multiple-input feedback control, user guidance, automatic calibration, self-diagnostics, and intelligent alarms.