Pain model and fuzzy logic patient-controlled analgesia in shock-wave lithotripsy

Abstract

Pain control in conscious patients was investigated using a push-button, demand-driven supply of drugs. A fuzzy logic patient-controlled analgesia (PCA) algorithm was compared with a conventional algorithm, for alfentanil administration in extracorporeal shock-wave lithotripsy. The conventional PCA algorithm used an initial dose of 0.25mg, a fixed infusion rate of 60 mg h(-1) and a fixed bolus size of 0.2 mg with a 1 min lockout. The fuzzy logic PCA algorithm used an initial dose of 0.25 mg, a changeable infusion rate and a bolus size of 0.1 or 0.05 mg. The infusion rate was adjusted according to a look-up table that accepted the button-pressing history over the last three lockout intervals. The look-up table was designed using fuzzy logic. The bolus size was adjusted according to the button-pressing history over the past two lockout intervals. Twelve patients were treated using conventional PCA, and thirteen were treated with PCA + fuzzy logic control (FLC). PCA + FLC patients consumed 45% less drug. Also, PCA + FLC patients had a mean delivery/demand ratio of 82%, compared with 60% in conventional PCA. When the pain intensity scale was analysed, PCA + FLC patients had acceptable pain intensity at 62%, compared with 44% in conventional PCA.

Artificial neural networks in urolithiasis

“…Shieh et al [26] compared a fuzzy logic system with a conventional patient-controlled analgesia algorithm for pain control during ESWL with promising results. Newer genetic adaptive ANNs, described in prostate cancer [27,28], use supervised learning incorporating evolutionary mechanisms of survival and genesis, allowing solutions to evolve over time.…”

Recent advances in patient-controlled sedation

“…Shieh et al [8], in a study of PCS for lithotripsy discussed above, briefly discuss the relevance of the demand/delivery ratio to patient satisfaction or impression of adequate self-control. They found this ratio to be closer to one in the PCS/fuzzy-control group compared with the physician administered analgesia group.…”

“…Thus, limiting aggression will degrade robustness. One interesting approach to the aggression issue was described by Shieh et al [8] -fuzzy logic PCA. The system employed a fuzzy logic control system that adjusts the size of the bolus and basal infusion based on the recent history of button press activity.…”

Patient-controlled sedation in procedural care

“…An Ohmeda 9000 pump was programmed to adjust the size of the bolus and basal infusion according to the history of demand activity [65]. Although this is a novel design of the PCS model, this study did not attract followers.…”