An Advisory System for Propofol Anaesthesia After Determining the Sensitivity of the Patient During the Induction Stage

Determining the sensitivity of the patient (SOP) during the induction stage is important because it is related to the confidence of the anaesthetist in controlling this system. Not only does this stage involve no surgical disturbances or artifacts, it is also fast and dynamic and very suitable for identifying the response of the patient to the drug. Eight patients underwent major abdominal surgery during intravenous anaesthesia and were all classified as ASA physical status category 1 or 2. A personal computer was connected via the RS232 ports for the Dinamap (i.e., Critikon, Inc., USA) and the Graseby 3400 syringe pump (i.e., Graseby Medical Limited, UK). All the trials measured patients' systolic arterial pressure (SAP) and heart rate (HR) using a Dinamap instrument. The clinical signs (i.e., sweating (SW), lacrimation (LA), and pupil response (PR)) were observed and input regularly about 5 min by the anaesthetist. A Graseby 3400 syringe pump which can pump from 0.1 to 1200 ml/hr was used to infuse propofol. Fentanyl was injected manually by syringe according to the rule-base. Also, a hierarchical fuzzy logic monitoring and rule-based control advisory system is tested in this paper to assess the determining the patient's sensitivity in the induction stage. The patient sensitivity of the elicited rule-base from anaesthetists' experience has been tested with the 8 patients during induction stage. Therefore, the good recovery time between acceptable and fast was 75 % in 8 patients. And, the mean (SD) of recovery time was 8.13 ± 5.94 min. Furthermore, the monitoring depth of anaesthesia (DOA) in terms of deciding of the confidence of depth of anaesthesia (CDOA) has also been tested with the 8 patients during maintenance stage. The mean (SD) of the mean CDOA in 8 patients was 93.55 ± 5.80 %. We conclude that determining the SOP in the induction stage is important because it is related to the confidence of the anaesthetist in controlling this advisory system. But a longer series of patients is needed to refine the rule-bases of the SOP, and to see how widely they are applicable.