The triad of anaesthesia

 

Perioperative monitoring of analgesia, consciousness and muscle relaxation

1. Using parameter specific monitoring devices

 

Objective assessment of nociception in anesthetized patients is a key challenge in medicine.

During general anesthesia, a patients’ body reacts to painful stimuli – although it is not consciously recognized. This intraoperative pain can stress the patient’s body and worsen pain after surgery. As the patient cannot communicate it is hard for clinicians to evaluate.

  • Throughout the surgical procedure, anesthetized patients are continuously monitored for hypnosis and muscle relaxation. Nociception/analgesia are currently assessed by monitoring changes in heart rate (HR), blood pressure (BP), and other indirect parameters which are not sensitive or specific to nociception.
  • Consequently, the patient may be given insufficient analgesia, which can promote postoperative pain, or excessive analgesia which can result in overdosing and related complications. 

With one multi-parameter fingersensor the anesthesiologist can access a objective view on the patients nociceptive status using the Medasense NOL patientmonitor.

Bispectral Index™ (BIS™) monitoring systems and the Carescape BIS monitor module enable anesthesia professionals to access processed EEG information as a measure of the effect of certain anesthetics during the care of patients they select to monitor. The clinical impact of BIS™ monitoring has been demonstrated in a variety of randomized controlled trials that reveal the potential for BIS monitoring to facilitate improvements—including patient safety—in anesthesia care.

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 relaxation 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.

 

Perioperative monitoring of analgesia, consciousness and muscle relaxation

2. Using the Carescape Monitoring system integrated parameters - Adequacy of anaesthesia

 

Monitoring Pain - Surgical Pleth Index SPI

SPI represents the patient’s hemodynamic responses to surgical stimuli and analgesic medication under general anesthesia.

SPI reflects the patient’s responses, which result from increased sympathetic activity as a
reaction to painful (nociceptive) stimuli. SPI monitoring is based on the acquisition of the readily available plethysmographic pulse wave, which is processed with a unique algorithm. The calculation analyzes the photoplethysmographic amplitude and the photoplethysmographic pulse interval, and then combines these two parameters to create a single digit, the Surgical Pleth Index. The details of the SPI algorithm have been published in an article in the British Journal of Anaesthesia titled “Assessment of surgical stress during
general anaesthesia”.

Dans l'écran partagé AoA unique du système, l'application BalanceView permet de combiner les valeurs SPI (indice de pléthysmographie chirurgicale) et SE (entropie d’état, une des composants de la mesure de l’entropie), et de les représenter sous une forme graphique.

Monitoring Hypnosis - Entropy measurements and monitoring

The GE Entropy™ Module is indicated for adult and pediatric patients older than 2 years within a hospital for monitoring the state of the brain by data acquisition of electroencephalograph (EEG) and frontal electromyograph (FEMG) signals. The spectral entropies, Response Entropy (RE) and State Entropy (SE), are processed EEG and FEMG variables. In adult patients, Response Entropy (RE) and State Entropy (SE) may be used as an aid in monitoring the effects of certain anesthetic agents, which may help the user to titrate anesthetic drugs according to the individual needs of adult patients. Furthermore in adults, the use of Entropy parameters may be associated with a reduction of anesthetic use and faster emergence from anesthesia. The Entropy measurement is to be used as an adjunct to other physiological parameters.

Bispectral Index™ (BIS™) monitoring systems and the Carescape BIS monitor module enable anesthesia professionals to access processed EEG information as a measure of the effect of certain anesthetics during the care of patients they select to monitor. The clinical impact of BIS™ monitoring has been demonstrated in a variety of randomized controlled trials that reveal the potential for BIS monitoring to facilitate improvements—including patient safety—in anesthesia care.

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 relaxation 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.