Closed-loop administration of analgesic drugs based on heart rate variability analysis.

General anesthesia is based on the use of hypnotic, muscle relaxant and analgesic drugs in order to render the patient unresponsive to the surgical procedure. The difficulty for anesthesiologists is then to determinate the minimum efficient dose to avoid any risk of under or over dosing. For several years, monitoring systems were developed in order to measure depth of hypnosis, myorelaxation and analgesia. As soon as all these monitoring systems became available, several teams worked on the closed-loop administration of anesthetic agents. We have developed a closed-loop system allowing the automatic administration of analgesic drugs. This system is based on the analysis of a heart rate variability based index: the ANI (Analgesia Nociception Index). In this paper, we describe this device and demonstrate its efficiency, repeatability and safety in a simulation environment.

Automated analgesic drugs delivery guided by vagal tone evaluation: interest of the Analgesia Nociception Index (ANI).

Analgesic drugs delivery optimization constitutes one of the main objectives of modern anesthesia. Indeed, their over or under determination constitutes a risk for anesthetized patient in terms of hemodynamic reactivity or post-operative hyperalgesia. Nowadays, new physiological indexes allow anesthesiologists to evaluate the balance between the analgesia level and the noxious stimulus importance. ANI is an index related to the autonomic nervous system activity based on heart rate variability analysis. Its ability for the analgesia / nociception balance evaluation has been established bringing evidences about its helpfulness for analgesic drug delivery. In this article, we describe a device for automatic analgesic drugs administration based on the ANI evolution during surgical procedures under general anesthesia. We hypothesized that such a device could improve the quality and safety of anesthesia by reducing adverse cardiovascular events and delivered analgesic drugs doses.

Heart rate variability analysis for arterial hypertension etiological diagnosis during surgical procedures under tourniquet.

Pneumatic tourniquets are widely used to provide a bloodless operative field during upper or lower limb surgery. If tourniquet inflation during general anesthesia is initially a mild stimulus, a long duration of inflation can imply heart rate and blood pressure increasing. However, heart rate or blood pressure increasing can also be caused by other external stimuli. Indeed, in the case of an insufficient analgesia, painful surgical stimuli can also cause an increase in heart rate and blood pressure. Therefore, in the case of the use of a tourniquet during surgery, it's very difficult for the anesthesiologist to distinguish hypertension caused by pain from hypertension caused by tourniquet inflation. In such a case, an efficient and reliable hypertension diagnosis could help the anesthesiologist in the medication choice. We have previously developed and evaluated an Analgesia / Nociception Index (ANI) based on the magnitude analysis of the respiratory patterns on the RR series. We hypothesize that the use of such an index could help in the arterial hypertension etiological diagnosis during surgical procedures under tourniquet.