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Correspondence  |   March 2006
An Unusual Event with the Bispectral Index® Monitoring System
Author Affiliations & Notes
  • Bachar Hachwa, M.D.
    *
  • *The Ohio State University, Columbus, Ohio.
Article Information
Correspondence
Correspondence   |   March 2006
An Unusual Event with the Bispectral Index® Monitoring System
Anesthesiology 3 2006, Vol.104, 619. doi:
Anesthesiology 3 2006, Vol.104, 619. doi:
To the Editor:—
We have had concerns with the new Bispectral Index® Monitoring System (BIS®) Quatro sensor electrode from Aspect Medical Systems (Newton, MA) with respect to the possibility of causing frequent “paper cuts,” or pressure groove injuries, to the foreheads of patients because of its design, in particular, its sharp proximal edge.
During one recent cardiac case, a BIS® Quatro sensor was placed properly on a patient’s forehead at induction with specific attention given to avoid injury to the patient’s forehead by the proximal edge. However, at the onset of cardiopulmonary bypass, the pulmonary artery catheter was withdrawn 2 cm, which caused the electrode’s position to shift, as demonstrated in figure 1. It was not until later that a pressure groove was noted on the patient’s forehead, as shown in figure 2, and the electrode was repositioned.
Fig. 1. The electrode’s position during cardiopulmonary bypass. 
Fig. 1. The electrode’s position during cardiopulmonary bypass. 
Fig. 1. The electrode’s position during cardiopulmonary bypass. 
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Fig. 2. The pressure groove on the patient’s forehead. 
Fig. 2. The pressure groove on the patient’s forehead. 
Fig. 2. The pressure groove on the patient’s forehead. 
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We suggest that Aspect Medical should reconsider the design of its electrodes. Practitioners should also consider placing a small piece of gauze under the proximal edge of the electrode to reduce any harm.
*The Ohio State University, Columbus, Ohio.
Fig. 1. The electrode’s position during cardiopulmonary bypass. 
Fig. 1. The electrode’s position during cardiopulmonary bypass. 
Fig. 1. The electrode’s position during cardiopulmonary bypass. 
×
Fig. 2. The pressure groove on the patient’s forehead. 
Fig. 2. The pressure groove on the patient’s forehead. 
Fig. 2. The pressure groove on the patient’s forehead. 
×