Overview

Adequate anesthesia results from a balance of many components, and needs to be assessed with more than one parameter. When the Surgical Pleth Index is used together with other monitored parameters, such as hemodynamics, NMT, and Entropy, you can get a complete picture of the patient’s status combined on one screen.

Benefits and Technology

BENEFITS   

Entropy measurement may be used as an aid in monitoring the effects of certain anesthetic agents in adults and may help the user titrate anesthetic drugs according to the individual needs in adults. GE entropy parameters may also be associated with a reduction of anesthetic use and faster emergence from anesthesia with adult patients.   

NMT aids in obtaining optimal conditions for surgery - timing and dosing of NMBAs for safe extubation and for safer recovery from neuromuscular blockage.   

Surgical Pleth Index (SPI) can be used to help assess both acute nociceptive events, as well as long-term state reactions during general anesthesia.   

TECHNOLOGY

Entropy Monitoring

Entropy* is an innovative clinical measurement designed to provide information on the state of the brain on hospital patients older than 2 years. Entropy monitoring is based on acquisition and processing of raw EEG and Frontal Electromyograph (FEMG) signals by using the Entropy algorithm, GE Healthcare’s application of spectral entropy easurement. Entropy is available as a module with CARESCAPE* Modular Monitors with OR and PACU softwares.   

See the algorithm publication at: Description of the Entropy* algortihm as applied in the Datex-Ohmeda S/5TM Entropy Module, Acta Anresthesiologica Scandinavica 2004; 48: 154-161, H. Viertio-Oja, V. Maja, M. Särkelä, P. Talja, N. Tenkanen, H. Tolvanen-Laakso, M. Paloheimo, A. Vakkuri, A. Yli-Hankala, P. Merilainen.

NMT Monitoring

Neuromuscular Transmission (NMT) is the transfer of an impulse between a nerve and a muscle in the neuromuscular junction. NMT can be blocked by neuromuscular blocking agents – drugs which cause transient muscle paralysis and prevent the patient from moving and breathing spontaneously. Muscle relaxation is used during general anesthesia to enable endotracheal intubation and to provide the surgeon with optimal working conditions. In critical care, muscle relaxation is used during mechanical ventilation to minimize the patient’s work of breathing and to improve oxygenation. 

Neuromuscular transmission monitoring in GE’s products provides integrated measurement of the level of neuromuscular block. It also offers plexus stimulation for Regional Block. The stimulation modes are train of four (TOF), single twitch (ST), double burst stimulation (DBS) and post tetanic count (PTC). NMT monitoring is available for CARESCAPE* Modular Monitors as a module.

SPI Monitoring

The Surgical Pleth Index (SPI, earlier called SSI), is a digit that may be used to monitor the patient’s hemodynamic responses to surgical stimuli and analgesic medications during general anesthesia. SPI reflects the patient’s responses, which result from increased sympathetic activity as a reaction to painful (nociceptive) stimuli.   

The details of the SPI algorithm have been published in an article in the British Journal of Anaesthesia 98, 447-455 (2007) titled, “Assessment of surgical stress during general anaesthesia”. Huiku, M., et al   

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