System and method of assessing analgesic adequacy using biopotential variability

Abstract

The system and method for predicting and measuring a subject's analgesic state and analgesic adequacy. Biopotential signals are obtained from a subject through electrodes. A processor will compute a measure that is representative of the subject's sedative state and / or muscle activity. A metric representative of such measures is then determined. In the case where a measure is taken of both the subject's sedative state and muscle activity the two measures are combined into an index representative of the subject's analgesic state and analgesic adequacy.

Description

CROSS REFERENCE TO RELATED APPLICATION [0001] This application claims benefit of Provisional Application Ser. No. 60 / 787,992 filed on Mar. 31, 2006.FIELD OF THE INVENTION [0002] The field of the present invention relates to medical monitoring tools, and more particularly, to a system and method for predicting and measuring a subject's analgesic state and analgesic adequacy. BACKGROUND OF THE INVENTION [0003] A patient undergoing anesthesia for a surgical procedure generally receives one or more pharmacological anesthetic agents. Different anesthetic agents produce different effects, the most important of which are sedation or hypnosis (the lack of consciousness or awareness of the surrounding world), analgesia (the blunting or absence of pain) and paralysis (lack of movement). Anesthetic agents may provide one or more of these effects and to varying extents. For example, neuromuscular blocking agents provide potent paralysis, but no sedation or analgesia. Opioids provide analgesia a...

AI Technical Summary

Problems solved by technology

The anesthetic administration is complicated by the multiple effects of the administered anesthetic agents.

For example, since volatile agents have analgesic as well as sedative effects, an increase in the administered concentration of a volatile agent will result in a concomitant, and possibly undesired, increase in analgesic effect.

All anesthetic agents have deleterious effects associated with excessive doses.

These measures are nonspecific, however, and a patient may experience significant pain without exhibiting any of them.

In addition, agents administered to maintain blood pressure and heart rate within desired ranges may abolish hemodynamic responses.

The measurement of pain is difficult, since patient descriptions vary.

However, since different patients have different pain thresholds and expectations, VAS assessments are inherently limited.

In addition, VAS assessments are not useful when a patient cannot respond, such as during surgery.

In addition, deeper anesthetic intraoperative hypnotic levels have been linked with increased rates of postoperative mortality [Monk T G, Saini V, Weldon B C, Sigl J C: Anesthetic Management and One-Year Mortality after Noncardiac Surgery.

While excessive doses of the various anesthetic agents may have deleterious effects, inadequate doses may result in different but also undesirable effects.

While monitoring means exist to determine the adequacy of the sedative / hypnotic and paralytic states, no similar monitoring technology allows the objective assessment of analgesic state and analgesic adequacy.

However, they do not teach a method of determining analgesic state or analgesic adequacy, nor do they teach how to resolve the separate influences of the level of consciousness and pain on the EEG signal.

None of the systems proposed to date has disclosed a system or method of which would allow such a determination.

Images