Changes in the Bispectral Index in Response to Experimental Noxious Stimuli in Adults under General Anesthesia

Objective. Pain assessment is a major challenge in nonverbal patients in the intensive care unit (ICU). Recent studies suggest a relationship between the Bispectral Index (BIS) and nociceptive stimuli. This study was designed to examine changes in BIS in response to experimental noxious stimuli. Methods. Thirty participants under general anesthesia were in this quasiexperimental, within subject, pre- and poststudy. In the operating room (OR), BIS was monitored during moderate and severe noxious stimuli, induced by a thermal probe on the participants’ forearm, after induction of general anesthesia, prior to surgery. Results. Significant increases in BIS occurred during moderate (increase from 35.00 to 40.00, ) and severe noxious stimuli (increase from 37.67 to 40.00, ). ROC showed a sensitivity (Se) of 40.0% and a specificity (Sp) of 73.3% at a BIS value？>？45, in distinguishing a moderate from a severe noxious stimuli. Conclusion. BIS increased in response to moderate and severe noxious stimuli. The Se and Sp of the BIS did not support the use of the BIS for distinction of different pain intensities in the context of deep sedation in the OR. However, the results justify further studies in more lightly sedated patients such as those in the ICU. 1. Introduction Pain is commonly experienced during a stay in the intensive care unit (ICU). It is recognized that several procedures such as turning, endotracheal suctioning, and drain removal are painful, even for intubated and sedated patients [1]. However, pain assessment is a major challenge for health professionals since several barriers limit patients’ verbal communication and their ability to self-report pain [1–4]. In those who can communicate, up to 80% report having suffered moderate to severe pain during their ICU stay, suggesting an urgent need to enhance pain management in the context of critical care [1, 3, 5]. Pain under treatment may lead to a number of adverse physical consequences including respiratory complications [5–7]. In addition, when acute pain is inadequately relieved, it may contribute to increase the risk of developing chronic pain [8, 9]. This can have a serious impact on the individual’s level of functioning and cause great emotional distress, hindering quality of life, and long-term well-being [10]. Such findings strengthen the importance of improving pain assessment and management in the ICU. The American Society of Pain Management Nursing (ASPMN) published clinical recommendations pertaining to pain assessment in nonverbal patients, such as those who are unconscious or sedated and