Zohn Centimole:A randomized controlled trial of anesthesia guided by BIS vs. standard care and effects on cognition

Title: A randomized controlled trial of anesthesia guided by BIS vs. standard care and effects on cognition. Keywords: anesthesia, cognitive function, BIS monitor, elderly Abstract: Postoperative cognitive dysfunction (POCD) is a subtle deterioration of cognitive function affecting one or many cognitive domains observed after exposure to anesthetics. These deficits in advanced cognitive functions and predictable memory continue after appropriate drug half-lives have expired, lasting from days to years. The incidence of POCD ranges from 10-50% depending on group. This cognitive decline is associated with increased one year mortality, as well as morbidity and family/caregiver stress. The domains most affected are attention and cognitive speed but also affect executive function and memory. A widely researched hypothesis for the mechanisms underlying POCD alterations is neurotoxic injury. Although there are many different anesthetics, the inhalation anesthetics are the basis of anesthesia used today. It is well described that inhalation anesthetics have neuropathogenic links similar to the senile dementias including Alzheimer’s disease. Multiple neuropathogenic mechanisms of inhalation anesthetic have been described. Anesthetic techniques that rely on high concentrations of volatile anesthetics expose patients to high cumulative exposure. A balanced anesthetic technique utilizing multiple drugs exposes patients to a lower cumulative volatile anesthetic dose. The long-term goal of this program of research is to elucidate an anesthetic technique that results in improved outcomes (less incidence of postoperative cognitive impairment) from anesthesia. One such technique showing great promise is electroencephalographic (EEG) guided anesthesia. Electroencephalographic activity monitors utilize time-domain, frequency-domain, and dual spectral analysis of raw EEG signals to objectively measure level of consciousness. The application of the Fourier transformation to EEG waveforms and subsequently, the correlation with depth of anesthesia ushered in bedside monitors to guide anesthesia dosing. Gan et al. (1997) established early that a secondary benefit of this guided technique was a 13.4% reduction in anesthetic drug consumption. Investigators have further sought to associate avoidance of deep anesthesia (brain monitor values