Improved detection of adverse cardiovascular trends with the use of a two-variable computer alarm

Assessment of preload and afterload of patients having undergone cardiac surgery is commonly done by the monitoring of mean arterial and left atrial pressures (MAP, LAP). In this ICU, a central computer has been in use to sample routinely the MAP and LAP every 10 min. This computer has been programmed to activate an alarm sequence if a routinely acquired value of MAP or LAP is found to be outside of preset ("trend") limits. The computer then initiates a repeat mode of sampling of MAP and LAP as 1 min intervals. If three consecutive repeated values of either variable remain outside of the preset limits, then the following occurs: 1) a plot of the trend of MAP and LAP over the preceding 3 h appears on the bedside video monitor, 2) a bedside light and audible chime are activated, and 3) the bedside keyboard is locked out to other functions until the alarm is reset. A study showed that this system can detect adverse trends appropriately, averaging only 1-2 false alarms/patient per 8-h shift.