Clinical trial NCT01377636: Measurement of Bispectral Index and Awareness in Patients Undergoing Electrophysiology Studies With Isoproterenol
Official title: Study to Measure BIS and Awareness in Patients Receiving Isoproterenol During Catheter Ablation for Atrial Fibrillation
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Intraoperative Awareness
Keywords: Isoproterenol
Bispectral index (BIS)
electrophysiology studies (EPS)
Lead sponsor: NYU Langone Health
Sponsor class: OTHER
First posted: 2011-06-21
Enrollment: 20
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: NA
Intervention model: SINGLE_GROUP
Primary purpose: TREATMENT

Brief summary: Isoproterenol is used as a cardiac stimulant in electrophysiology studies (EP). Preliminary data suggests that administration of isoproterenol increases the Bispectral index (BIS). BIS is used to monitor neuronal signals under anesthesia. The BIS level is suggested to correspond to the level of consciousness. We hypothesize that isoproterenol increases BIS values because it increases the patient's level of consciousness through its central nervous system (CNS) stimulatory effects. In this study, we will administer increasing doses of isoproterenol to EPS patients. We will measure the BIS levels continuously before and after isoproterenol administration. In addition, we will test the level of awareness of patients by their response to a modified isolated forearm technique.

Detailed description: Isoproterenol is a direct acting Beta-1 and Beta-2 agonist useful for its effects on bronchodilation and myocardial contractility. Its CNS side effects include nervousness, headache, dizziness, restlessness, insomnia, anxiety, tension, blurring of vision, fear, and excitement. In addition to our preliminary data, two case reports show an increase in BIS with administration of isoproterenol. Our hypothesis is that administration of isoproterenol will increase the level of consciousness of the patient as reflected in the BIS reading.

The BIS Vista Monitor is a non-invasive device that measures the electrical activity of the brain. It computes a number between 0 and 100 which corresponds to a level of consciousness which is known as the Bispectral (BIS) value. Using the BIS value to guide administration of anesthetic medication, clinicians can make informed decisions for optimal anesthesia. This technology has the potential to prevent over sedation, but is currently not a standard monitoring device.

Another approach to evaluating the level of consciousness of anesthetized patients is to assess their ability to form memories or recall events which occurred while under anesthesia. Conscious recall is the first to disappear with decreasing levels of consciousness. A BIS of 60 or less has been shown in various studies to be sufficient to prevent conscious recall in the vast majority of patients. We propose to use a modified isolated forearm technique test in which the patient is asked to squeeze an observer's hand during anesthesia to ascertain if awareness can occur without recall at a BIS of 60 to 70. (6) Implicit memory in which there is no conscious recall or evaluation of awareness can be assessed by word stem completion tests and has been shown to occur with a BIS as low as 40 - 60 although these results are not consistent across all studies. (7)

Eligibility criteria: Inclusion Criteria:

* Patients scheduled for EP studies for catheter ablation of atrial fibrillation under general anesthesia will participate in the study

Exclusion Criteria:

* Patients with neuromuscular disease precluding the use of succinylcholine will be excluded.
* Patient or cardiologist refusal

Primary outcomes:
measure: Number of Participants With an Increase in BIS Readings During Steady State
timeFrame: During time of Electrophysiology (EP) studies.
measure: BIS Change
timeFrame: Within 20 minutes of starting isoproterenol infusion
Secondary outcomes:
measure: Number of Participants With Spontaneous Musculoskeletal Movement
timeFrame: Within 20 minutes of starting isoproterenol infusion
measure: Number of Participants Who Follow Verbal Command to Squeeze Hands
timeFrame: Within 20 minutes of starting isoproterenol infusion
Other outcomes:
measure: Number of Participants With Significant Change in Heart Rate
timeFrame: Within 20 minutes of starting isoproterenol infusion
measure: Number of Participants With Change in Blood Pressure
timeFrame: Within 20 minutes of starting isoproterenol infusion
measure: Number of Participants With Amnesia or No Recall During Steady State
timeFrame: Within one hour of completing anesthesia
measure: Number of Participants With New Arrhythmia During Steady State.
timeFrame: Within 20 minutes of start of isoproterenol
measure: Number of Participants Who Developed Ischemia or ST Segment Changes
timeFrame: Within 20 minutes of starting isoproterenol infusion
Locations:
city: New York City
country: United States
facility: NYU Langone Medical Center, Department of Anesthesiology
state: New York
Study officials:
affiliation: NYU School of Medicine
name: Patrick Linton, MD
role: PRINCIPAL_INVESTIGATOR
References:
citation: O'Neill DK, Aizer A, Linton P, Bloom M, Rose E, Chinitz L. Isoproterenol infusion increases level of consciousness during catheter ablation of atrial fibrillation. J Interv Card Electrophysiol. 2012 Aug;34(2):137-42. doi: 10.1007/s10840-011-9652-3. Epub 2012 Feb 25.