N THE LAST TWO decades many of the advances in medicine and surgery have been made possible by an increased knowledge and use of electronics. Among the machines and electronic devices which have had a marked effect on patient care are the cardiac pacemaker-monitor, Thermorite and alternating air mattresses, electronic oxygen tents, and many different types of suction machines. The operating of these and other machines is a technical skill required of today's registered nurse. We were part of a team of nurses on the intensive care unit at University Hospital of the New York University Medical Center who were responsible for using two different electronic patient-monitoring devices on an experimental basis. As patients were admitted to the unit, the nursing care they required was evaluated. Patients whose condition required monitoring of vital signs every hour or more frequently were selected for the study. Because we were interested in studying the effectiveness of the machines, we devised a form on which the details of the nursing activity, the patients' reactions, the accuracy of the machines, and general comments could be recorded. The machines looked wonderful, but we were a little skeptical. Some of the questions to which we sought answers were the following: * What is the patient's reaction to the use of monitoring devices? * What are the effects of the devices on the patient's comfort, freedom of motion, and safety? * How do the patient's condition, activity,'level of consciousness affect the accuracy of results? * What differences occur in the nurse's approach to the patient and is there a difference in the amount or type of patient contact? We used two machines in the study and we called them Monitor I and II. Monitor I consisted of four separate units to record blood pressure, temperature, pulse, and respirations. A standard blood pressure cuff and a small, highly sensitive microphone placed on the patient's forearm or just below the antecubital fossa recorded the systolic and diastolic pressures. We could obtain a recording by depressing the switch, or set it to record automatically in a twoor four-minute cycle. Each blood pressure reading remained visible on the dials until the next cycle. The cuff pressure had to be set at 20 to 30 mm. of mercury above the patient's systolic blood pressure and bel w the diastolic. Therefore, if the blood pressure were higher or lower than the setting, the monitor reading would be incorrect.