Intensive Care
Planning
Patient under sedation
(click to enlarge)
The Algorithm
The first step was to develop a simple set of rules for managing sedation. In the process of developing the rules, the team improved their understanding of sedation management dynamics. Current sedation-agitation scoring systems place sedation and agitation at the opposite ends of a continuum, but the researchers realised that patients can show signs of agitation and sedation simultaneously. Instead of a continuum, they developed the concept of managing agitation and sedation independently, and incorporated it into their rules.
The completed set of rules was developed into a mathematical algorithm based on the principle that a patient’s sedation needs can be predicted by their recent medication history. The algorithm also had to provide for nursing intervention via boluses (small volumes of drug, rapidly delivered), and a gradual decrease in the background infusion rate (to wean patients off sedation).
The result is an algorithm that calculates the infusion rate as two-thirds of the average of the patient’s total infusion administered over the previous four hours. Nurses can intervene by adding boluses which are included in the sum. The reduction factor of two-thirds allows the background infusion rate to drop away when there is no agitation and so no boluses; but for as long as agitation continues, a background infusion is maintained.
Paper trial
The innovation was first tested by plotting the algorithm as a paper chart which nursing staff implemented using manual calculations. This low-risk trial of the new sedation management protocol cost next to nothing.
Patients were given a background infusion of the painkiller morphine (1.0mg/ml) mixed with the tranquiliser midazolam (0.5mg/ml). Nurses gave an additional dose in the form of a bolus if the patient became agitated (typically 0.5 – 2.0ml depending on the patient’s age and weight). Every four hours nurses summed the total volume of drugs infused to manage the patient and, using the algorithm, calculated a new rate of infusion.
The paper trial confirmed the potential benefits of the new protocol for both patients and staff. Feedback refined the algorithm and background infusion rates were recalculated hourly for greater precision.
Mr Dove, overseer of the design of the Infuse-Rite, stresses the importance of this initial testing and the patience of the ICU nurses which allowed the team to optimise the design.
