E EDITORIAL
Preventing Delirium After Cardiothoracic Surgery: Provocative but Preliminary Evidence for Bispectral Index Monitoring Miles Berger, MD, PhD, Jacob Nadler, MD, PhD, and Joseph P. Mathew, MD
E
ver since Bedford’s seminal 1955 case series in the Lancet titled “Adverse Cerebral Effects of Anesthesia on Old People,” we have known that some patients have cognitive problems after anesthesia and surgery.1 Today, the term postoperative delirium is often used to describe the mental state of many of these patients. Delirium is a syndrome of waxing and waning mental status changes and alterations in the level of consciousness. It is a common (and likely underrecognized) complication correlated with adverse outcomes including decreased quality of life and increased hospital and 6-month mortality.2 More recently, postoperative delirium has also been associated with cognitive decline during the first year after cardiac surgery.3 Is there anything that we as anesthesiologists can do to decrease the incidence of delirium? Processed electroencephalography (EEG) (e.g., Bispectral Index, BIS) is a controversial tool in anesthesiology but may be a useful instrument for preventing postoperative delirium. In this issue of Anesthesia & Analgesia, Whitlock et al.4 examine whether using a BIS monitor decreases the incidence of delirium in cardiothoracic surgery patients. They report a trend toward less delirium in the BIS-guided anesthetic group versus the end-tidal anesthetic concentration (ETAC)-guided group (18.8% vs 28%), although this difference was not statistically significant (P = 0.058) despite adequate statistical power. Nevertheless, this finding is consistent with the results of similar studies in noncardiac surgical patients, which have shown that BIS-guided anesthetic titration (as opposed to typical titration to hemodynamic end points) lowers the incidence of delirium.5,6 Even when spinal anesthesia was the primary anesthetic technique, titrating sedation depth to a BIS ≥80 vs approximately 50 decreased the incidence of delirium.7 In each of these studies, BIS usage (or a higher BIS target range) was associated with lower average anesthetic
From the Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina. Accepted for publication January 6, 2014. Funding: This work was supported by departmental funds. The authors declare no conflicts of interest. Reprints will not be available from the authors. Address correspondence to Miles Berger, MD, PhD, Department of Anesthesiology, Duke University Medical Center, 4324 Orange Zone (Duke South), Durham NC 27710. Address e-mail to [email protected]. Copyright © 2014 International Anesthesia Research Society DOI: 10.1213/ANE.0000000000000130
706 www.anesthesia-analgesia.org
dosage6,7 or a decreased incidence of deep anesthesia (e.g., BIS values
Preventing Delirium After Cardiothoracic Surgery: Provocative but Preliminary Evidence for Bispectral Index Monitoring Miles Berger, MD, PhD, Jacob Nadler, MD, PhD, and Joseph P. Mathew, MD
E
ver since Bedford’s seminal 1955 case series in the Lancet titled “Adverse Cerebral Effects of Anesthesia on Old People,” we have known that some patients have cognitive problems after anesthesia and surgery.1 Today, the term postoperative delirium is often used to describe the mental state of many of these patients. Delirium is a syndrome of waxing and waning mental status changes and alterations in the level of consciousness. It is a common (and likely underrecognized) complication correlated with adverse outcomes including decreased quality of life and increased hospital and 6-month mortality.2 More recently, postoperative delirium has also been associated with cognitive decline during the first year after cardiac surgery.3 Is there anything that we as anesthesiologists can do to decrease the incidence of delirium? Processed electroencephalography (EEG) (e.g., Bispectral Index, BIS) is a controversial tool in anesthesiology but may be a useful instrument for preventing postoperative delirium. In this issue of Anesthesia & Analgesia, Whitlock et al.4 examine whether using a BIS monitor decreases the incidence of delirium in cardiothoracic surgery patients. They report a trend toward less delirium in the BIS-guided anesthetic group versus the end-tidal anesthetic concentration (ETAC)-guided group (18.8% vs 28%), although this difference was not statistically significant (P = 0.058) despite adequate statistical power. Nevertheless, this finding is consistent with the results of similar studies in noncardiac surgical patients, which have shown that BIS-guided anesthetic titration (as opposed to typical titration to hemodynamic end points) lowers the incidence of delirium.5,6 Even when spinal anesthesia was the primary anesthetic technique, titrating sedation depth to a BIS ≥80 vs approximately 50 decreased the incidence of delirium.7 In each of these studies, BIS usage (or a higher BIS target range) was associated with lower average anesthetic
From the Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina. Accepted for publication January 6, 2014. Funding: This work was supported by departmental funds. The authors declare no conflicts of interest. Reprints will not be available from the authors. Address correspondence to Miles Berger, MD, PhD, Department of Anesthesiology, Duke University Medical Center, 4324 Orange Zone (Duke South), Durham NC 27710. Address e-mail to [email protected]. Copyright © 2014 International Anesthesia Research Society DOI: 10.1213/ANE.0000000000000130
706 www.anesthesia-analgesia.org
dosage6,7 or a decreased incidence of deep anesthesia (e.g., BIS values
