BIS and Entropy Nociception Monitoring
Condition: Pain
Study type: Observational

Summary: 
      Reports have been appearing in literature over the past years of various
      nociception-antinociception monitors, introduced and promoted from major manufactures.
      Recently a new term Practice misalignment" has been recently coined indicating research study
      groups that are distant from daily anesthesia practice, with some scientific relevance but
      very little clinical relevance simulating "purely hypothetical" conditions that are not
      related to "everyday" anesthesia practice.
    

Detailed description: 
      Background: Reports have been appearing in literature over the past years of various
      nociception-antinociception monitors, introduced and promoted from major manufactures.
      Recently a new term Practice misalignment" has been recently coined indicating research study
      groups that are distant from daily anesthesia practice, with some scientific relevance but
      very little clinical relevance simulating "purely hypothetical" conditions that are not
      related to "everyday" anesthesia practice. These proposed new nociception-antinociception
      parameters are assumed to be "immune" from confounding factors commonly encountered such as
      neuromuscular block, remifentanil, or cardiovascular haemodynamically active drugs.

      Methods: Investigators sought to quantify the basic components of these new
      nociception-antinociception parameters in response to various noxious stimuli, and then test
      them against the most confounding factors namely neuromuscular blocking agents (NMBAs) for
      sEMG, remifentanil analgesia and haemodynamic changes, while at the same time analysing the
      EEG and blood levels. Investigators examined two nociception -antinociception parameters
      basic components sBIS/sEMG and Response Entropy-State Entropy difference from the two main
      manufacturers GE and Medtronic.

      Fifty patients, aged 18-65 years, undergoing general surgery on the lower limb were randomly
      allocated to the BIS 25 or BIS 50 groups. Exclusion criteria included alcohol or drug abuse,
      chronic treatment with antihypertensive or cardiovascular medications including β-blockers,
      and medications acting on the central nervous system such as benzodiazepines, antiepileptic
      and neuroleptic medications, After capnographic verification of proper lungs ventilation with
      40% oxygen in air, either BIS 50 levels or BIS 25 were subsequently maintained via propofol
      TCI 0.2 microg mL-1 TCI adjustments. Stable BIS values that showed no further decline and
      remained within BIS ±5 of either BIS 50 levels or BIS 25 of the previous BIS value were
      considered an indicator of pseudo-steady state plasma effect-site equilibration. Two
      silver/silver chloride surface stimulating electrodes were placed 4 cm apart on the ulnar
      nerve at the wrist and connected to Innervator NS272 (Fisher & Paykel, Auckland, New Zealand)
      peripheral nerve stimulator. The ulnar nerve was stimulated in an ascending sequence of
      single twitch electric stimulations starting from 10 mA, up till 80 mA for a period of 10 s
      with a 3 min period between stimulations. BIS and Entropy data were recorded. After which
      patients were re-stimulated under remifentanil and again re-stimulated under NMBAs.
    

Observational model: Case-Control
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Fifty patients, aged 18-65 years, undergoing general surgery on the lower limb were
        randomly allocated to the BIS 25 or BIS 50 groups