Awareness During Blended Anaesthesia

Relationships Between Bispectral Index (BIS), Implicit Memory Dream Recall and MAC in Blended Anaesthesia

the aim of this study was to estimate the relations between Bispectral Index values and explicit or implicit memory or dreams during two different minimal alveolar concentration (MAC) of sevoflurane in patients undergoing blended anaesthesia for major abdominal surgery and ,in this way, estimate the possibility to reduce, in presence of a deep analgesia, like epidural analgesia, the requirement of halogenated volatile anesthetics.

Study Overview

• Status: Completed
• Conditions: Intraoperative Awareness; Consciousness, Level Depressed
• Intervention / Treatment: Device: monitor for depth of hypnosis

Detailed Description

The decreased responsiveness to stimulation defines depth of anaesthesia which is a balance between effects of anaesthetic drugs and surgical stimulations.

Awareness is a rare occurrence with an incidence of 0,1-0,2 % , defined as postoperative recall of events occurring during general anaesthesia.

Different stages of awareness should be defined: conscious awareness with explicit recalls with pain; conscious awareness with explicit recalls without pain; conscious awareness without explicit recall and possible implicit recall; subconscious awareness without explicit recall and possible implicit recall; no awareness .

This memory can be traumatic and may result in developing a chronic posttraumatic stress disorder (PTSD) in more than half of subjects .

Some cases of awareness are caused by inadequate anesthesia and are potentially avoidable through the assessment of depth of hypnosis by an intraoperative monitoring , especially when muscle relaxants are used.

The Bispectral Index ( BIS ), one of the devices designed to monitor brain activity, through a proprietary algorithm , elaborates EEG and provides an index of hypnotic level.

Thus, several variables, derived from EEG time and frequency domain, are combined into a single index indicating the patient's level of consciousness.

A range between 40 and 60, during surgery, permits both to prevent awareness and to reduce the dose of anesthetic agent administered .

In this study, during major abdominal surgery, an epidural analgesia was performed to suppress afferent noxious stimuli and combined with a general anaesthesia based on halogenates.

Thereby the aim of this study was to estimate the relations between Bispectral Index values and explicit or implicit memory or dreams during two different minimal alveolar concentration (MAC) of sevoflurane in patients undergoing blended anaesthesia for major abdominal surgery and ,in this way, estimate the possibility to reduce, in presence of a deep analgesia, like epidural analgesia, the requirement of halogenated volatile anesthetics.

• Study Type: Observational
• Enrollment (Actual): 36

Contacts and Locations

Study Locations

• Italy
  • Rm
    • Rome, Rm, Italy, 00168
      • Catholic University Of Sacred Heart

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 70 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Probability Sample

Study Population

patients undergoing elective major abdominal surgery

Description

Inclusion Criteria:

native Italian speakers American society of anaesthesiologist physical status I-II -

Exclusion Criteria:refusal of placement of epidural catheter neurological or psychiatric diseases hearing impairment use of drugs know to affect central nervous system coagulopathy heart conditions infections allergy to local anaesthetics liver or renal disease

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Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Bispectral Index Group	Device: monitor for depth of hypnosis; evaluation of depth of hypnosis --------------------------------------------------------------------------------

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
correlation between BIS and free association test score	every 15 min during anaesthesia and 24 h after emergency from anaesthesia

Secondary Outcome Measures

Outcome Measure	Time Frame
MAC of sevoflurane necessary to avoid awareness	24 h after emergency from anaesthesia

Collaborators and Investigators

• Sponsor: Germano De Cosmo
• Investigators: Principal Investigator: De Cosmo Germano, PhD, Catholic University

Publications and helpful links

General Publications

• Sandin RH, Enlund G, Samuelsson P, Lennmarken C. Awareness during anaesthesia: a prospective case study. Lancet. 2000 Feb 26;355(9205):707-11. doi: 10.1016/S0140-6736(99)11010-9.
• Ghoneim MM. Incidence of and risk factors for awareness during anaesthesia. Best Pract Res Clin Anaesthesiol. 2007 Sep;21(3):327-43. doi: 10.1016/j.bpa.2007.05.002.
• Wong CS. What's the matter of depth of anesthesia? Acta Anaesthesiol Sin. 2001 Mar;39(1):1-2. No abstract available.
• Schwender D, Klasing S, Daunderer M, Madler C, Poppel E, Peter K. [Awareness during general anesthesia. Definition, incidence, clinical relevance, causes, avoidance and medicolegal aspects]. Anaesthesist. 1995 Nov;44(11):743-54. doi: 10.1007/s001010050209. German.
• Osterman JE, Hopper J, Heran WJ, Keane TM, van der Kolk BA. Awareness under anesthesia and the development of posttraumatic stress disorder. Gen Hosp Psychiatry. 2001 Jul-Aug;23(4):198-204. doi: 10.1016/s0163-8343(01)00142-6.
• Baars BJ. The brain basis of a "consciousness monitor": scientific and medical significance. Conscious Cogn. 2001 Jun;10(2):159-64; discussion 246-58. doi: 10.1006/ccog.2001.0510.
• Ekman A, Lindholm ML, Lennmarken C, Sandin R. Reduction in the incidence of awareness using BIS monitoring. Acta Anaesthesiol Scand. 2004 Jan;48(1):20-6. doi: 10.1111/j.1399-6576.2004.00260.x.
• Aceto P, Valente A, Gorgoglione M, Adducci E, De Cosmo G. Relationship between awareness and middle latency auditory evoked responses during surgical anaesthesia. Br J Anaesth. 2003 May;90(5):630-5. doi: 10.1093/bja/aeg113.

Study record dates

Study Major Dates

• Study Start: September 1, 2005
• Primary Completion (Actual): February 1, 2009
• Study Completion (Actual): February 1, 2009

Study Registration Dates

• First Submitted: November 12, 2012
• First Submitted That Met QC Criteria: February 25, 2013
• First Posted (Estimate): February 27, 2013

Study Record Updates

• Last Update Posted (Estimate): February 27, 2013
• Last Update Submitted That Met QC Criteria: February 25, 2013
• Last Verified: February 1, 2013

More Information

Terms related to this study

• Keywords: Cerebral State Index Monitor
• Additional Relevant MeSH Terms: Mental Disorders; Pathologic Processes; Nervous System Diseases; Neurologic Manifestations; Neurobehavioral Manifestations; Neurocognitive Disorders; Intraoperative Complications; Consciousness Disorders; Intraoperative Awareness
• Other Study ID Numbers: A1044/2001