Bispectral Index® and the incidence of apnea during monitored anesthesia care

Purpose:

The Bispectral Index (BIS) provides an estimate of depth of consciousness during sedation. If apnea can be shown to correlate with BIS, then a potential improvement in safety during MAC/sedation may be achieved.

Scope:

Ninety-nine patients undergoing MAC anesthesia were monitored with BIS for level of consciousness, and capnography for apnea detection. The anesthesia provider was blinded to BIS and capnography data. Forty-nine percent of subjects experienced apnea independent of medical history, procedure, or medication. BIS immediately preceding apneic episodes (55 ± 18) was frequently lower than that recommended for an upper limit during general anesthetics (<60). The incidence increased as depth of consciousness decreased with a 50% likelihood of developing apnea at a BIS of 56.

Conclusions:

The incidence of apnea during MAC is high, and incidence increases as BIS decreases.