Evaluation of a "heads-up" display for cardiopulmonary bypass

Multiple variables must be analyzed during cardiopulmonary bypass in order to judge the adequacy of perfusion. Variables when viewed singly can be confusing and lead to inaccurate representation of the physiological status of the patient. Communication between the perfusionist and members of the surgical team requires accuracy and complete presentation of pertinent data. Toward this goal of improving the assimilation and processing of information during cardiopulmonary bypass, a multivariable computer-aided "Heads-up Display" (HUD) was developed. Modern jet pilots use heads-up display for rapid assimilation of information when making judgments about the performance of their aircraft and weapons systems. Heads-up display is an electronically generated display that is superimposed upon a pilot's forward field of view. An analogy between a jet pilot and a perfusionist can be made. A geometric form, a hexagon, is used as part of the heads-up display for cardiopulmonary bypass (CPB-HUD). The polygon represents a performance evaluation graph. Each of the six "spokes of a wheel" represents a physiological parameter. The represented variables are: cardiac index, peripheral vascular resistance, hematocrit, dynamic operating blood level, venous saturation, and mean arterial pressure. The perfusionist inputs target values. Target values are then compared to actual values and expressed as a percentage. If all targeted values are achieved, the graphical representation is a hexagon. The surgical team rapidly recognizes abnormal patterns that are outside individual target values. They include, but are not limited to, patterns of: vasoconstriction, vasodilatation, hypovolemia, decreased oxygen carrying capacity, and several others. The CPB-HUD has proved to be of value for planning, real time evaluation, retrospective analysis of cardiopulmonary bypass benchmark data, and as an aid in the teaching of new personnel concerned with cardiopulmonary bypass.