Progress of automatic drug delivery in anaesthesia—The ‘Rostock assistant system for anaesthesia control (RAN)’

Abstract

The main goals of general anaesthesia should include (not exclusively) adequate hypnosis, analgesia and maintenance of vital functions. In addition, neuromuscular blockade (NMB) may be needed for a number of surgical procedures. Patient safety and cost reductions via the minimization of drug consumption and the shortening of post-operative recovery represent some of the main issues and motivations of automation of anaesthesia.Since the early eighties engineers and physicians joined efforts towards the development of sophisticated closed-loop control systems for drug delivery in the operating theatre and post-operatively.First, this paper should be seen as a review about the automatic drug delivery in anaesthesia. A summary is given about the methods of measurement, modelling and general progress of closed-loop control systems in anaesthesia. In particular, the development of the 'Rostock assistant system for anaesthesia control (RAN)' is also described. This system has been developed during the last 15 years at the University of Rostock and various systems and control-based ideas have been integrated since. With this system the multiple-input-multiple-output (MIMO) control of the depth of hypnosis and NMB has been shown to be possible as well as the closed-loop control of a deep arterial hypotension. Promising results have already been obtained from a first study, which has so far included as many as 22 patients using MIMO control.

Coordinated semi‐adaptive closed‐loop control for infusion of two interacting medications

“…On the average, the coordinated controller exhibited intuitively relevant behaviors as the weights in the cost function (22) were varied, as described in the following (see Figure 7).…”

“…The abovementioned intuitive behaviors of the proposed coordinated semi-adaptive control approach may be useful in tuning the weights in the cost function (22) to customize its performance when applied to other medication infusion problems.…”

“…However, the majority of prior art has focused on the infusion of a single medication, eg, propofol, [13][14][15] remifentanil, 16,17 and fluid, 18,19 whereas there is only limited volume of work reported on the closed-loop control for infusion of multiple medications to track multiple reference targets (see, for example, previous works [20][21][22] ). In addition to closed-loop control design, the coordination of reference targets also presents a challenge.…”

Towards a Multivariable Model for Controlling the Depth of Anaesthesia using Propofol and Remifentanil

“…Opioids such as fentanyl, alfentanyl and Remifentanil are known to have synergistic effect on Propofol (Milne et al, 2003;Kazama et al, 1998;Simanski et al, 2009). Since general anaesthesia is clinically defined as the balance between hypnosis, analgesia and paralysis, it is interesting to study the effect of drug interaction (Milne et al, 2003).…”

“…the paralysis component of general anaesthesia) is not inter-related to the hypnotic and analgesic components (i.e. no drug interaction) (Da Silva et al, 2011;Simanski et al, 2009). On the other hand, it has been shown that the use of Remifentanil in regulated DOA has a sparing effect on Propofol infusion rates, hence with much less over-dosage occurrences (Milner et al, 2003).…”