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.

Reduction of unexpected, life-threatening events in postoperative cardiac surgical patients; the role of computerized surveillance.

With increasing use of computerized surveillance (CS) in critical care, a key question is whether it favorably influences clinical outcome. Knowing that two intensive care unit beds would soon have CS capability, we embarked on an uninterrupted prospective study in which the incidence of sudden, unexpected life-threatening events (SULTE) was compared in post-open heart surgery patients whose subsystem performances were evaluated by conventional methods (CM) as opposed to those who would be followed by CS involving automatic acquisition and generation of 30 cardio-respiratory variables. We evaluated 211 patients, 91 with CM and 120 by CS. Since CS availability was limited, sicker patients were given priority for the two CS beds. Despite the obvious bias in favor of CM, there was a statistically significant reduction (P less than 0.001) in the incidence of SULTE in those patients followed by CS (1 of 120 patients: 0.8%; no SULTE-related deaths) in comparison to the CM patients (11 of 91 patients: 12%; two SULTE-related deaths.) The data suggest that computerized surveillance can play a role in reducing morbidity and possibly mortality in postoperative cardiac surgical patients.

Circulatory support with a left-heart assist device after intracardiac operation: design concepts and management techniques.

A simple left-heart assist device was developed to reduce left ventricular preload while simultaneously increasing total systemic blood flow. It consists of special cannulas connected to a simple extracorporeal tubing loop and roller pump, designed to permit bypass of as much as 5 liters of blood per minute from left atrium to ascending aorta. Employed in 15 patients with advanced heart disease who were in low cardiac output following repair, the system was proven effective. An asset of the device is the ability to subsequently separate the patient from the device without need to reenter the thorax or abdomen.