Intraoperative EEG Marker of Preoperative Frailty in Elderly Patients
Condition: Frailty
MeSH terms: Frailty
Study type: Observational

Summary: 
      Frailty is a state of vulnerability, characterized by a loss of mechanisms that maintain
      homeostasis, determining a lower capacity for recovery in the event of a stressful incident.
      It is one of the risk factors that increase postoperative adverse outcomes in the elderly
      population. It has been associated with worse results in different surgical settings,
      including increased mortality, readmission, referral to specialized care units, increased
      costs and hospital stay. Currently, there are several instruments for diagnosis and screening
      of frailty. All of them require time for their execution, an experienced evaluator and an
      adequate validation in the population in which they are intended to be used. The use of
      frontal electroencephalography during the intraoperative period has become increasingly
      popular. It allows the monitoring of brain activity during the administration of anesthetics.
      Various intraoperative electroencephalographic markers, such as alpha spectral power or total
      spectrum power, have been associated with factors such as preoperative physical activity,
      preoperative cognitive level, comorbidities, and postoperative delirium. The objective of
      this study will be to determine an intraoperative frontal electroencephalographic marker of
      preoperative frailty in ≥ 65 years patients undergoing general anesthesia with Sevoflurane
      for non-cardiac surgery.
    

Detailed description: 
      The world health organization has estimated that the population over 60 years of age will
      increase exponentially between 2015 and 2050. This change will be more pronounced in
      developing countries, including Chile. Each year, the number of older people (≥ 65 years)
      undergoing surgical interventions raises. This is due to a sustained increase in life
      expectancy, demographic changes, and progress in surgical/anesthetic techniques that allow
      this population to undergo less invasive procedures. In addition, older patients have a
      higher risk of postoperative morbidity and mortality compared to younger people.

      Frailty is one of the risk factors that increase adverse postoperative outcomes in the
      elderly population. It is defined as a state of vulnerability or lack of physiological
      reserve that is characterized by an inadequate resolution of homeostasis after a stressful
      event. Frailty determines that an event can generate changes in the postoperative state of
      dependence of these patients; causing a person who was independent prior to surgery to end up
      requiring assistance with their activities of daily living after it. Frailty has been
      associated with worse outcomes in different surgical settings, including increased mortality,
      readmission, referral to specialized care units, increased costs and hospital stay. In
      addition, preoperative frailty has also been associated with postoperative delirium.

      Currently, there are several instruments for the diagnosis and screening of frailty that
      present good sensitivity and specificity. All of them require time for their execution, an
      experienced evaluator and adequate validation in the population in which they are intended to
      be used. Furthermore, with some instruments, specific elements may be required, for example
      the Handgrip dynamometer for the Fried phenotype. These conditions are not always easy to
      obtain in the local preoperative setting and the tools are not always adequately validated
      for non-English speaking populations. Moreover, there is uncertainty regarding which frailty
      instrument to choose among the dozens described in the literature, and there are time
      pressures that prevent the addition of more tests or evaluations in the preoperative clinic.

      The use of frontal electroencephalography (EEG) during the intraoperative period has become
      increasingly popular. It is used to obtain a real-time record of brain electrical activity
      during administration of anesthetics. Interpreting the EEG in the time domain in real time in
      the operation room is challenging. Therefore, various processed EEG monitors (BIS®, SedLine®)
      currently clinically used, have incorporated the spectral analysis to their records. The
      spectrum presents the advantage to show the frequency decomposition of the EEG segment for
      all frequencies in a given range (usually <30 Hz) by plotting the frequency on the X axis and
      power on the Y axis. The accumulation of spectra over time is called spectrogram and can be
      presented graphically on the monitor, where the X-axis represents time, Y axis the
      decomposition of frequencies, and the Z bar represents the amplitude or power of the
      different waves. With increasing age there is a decrease in spectral power and alpha wave
      coherence (8-12 Hz). In addition, decreased alpha spectral power during anesthetic
      administration has been correlated with preoperative cognitive dysfunction. Recently,
      preoperative physical activity, the spectral power of the alpha wave and the entire spectral
      band have been associated with postoperative delirium in the cardio-surgical population. In
      addition, the spectral power of the alpha wave and broadband power (baseline noise) has been
      correlated with changes in age and patient comorbidities.

      The objective of this study will be to determine an intraoperative frontal
      electroencephalographic marker of preoperative frailty in a population older than 65 years
      undergoing general anesthesia with sevoflurane for elective non-cardiac surgery. Our
      hypothesis is that frail patients (determined by the FRAIL, Clinical Frailty Scale and Fried
      scales) undergoing general anesthesia with sevofluorane for non-cardiac surgery have a lower
      alpha spectral power and lower entire spectral band power of the EEG compared to patients of
      similar age, who are robust, undergoing the same type of surgeries.
    

Intervention name(s): Intraoperative frontal electroencephalogram
Intervention type(s): Device
Intervention description(s): Intra operative frontal electroencephalogram registration with 1 age adjusted Minimum Anesthetic Concentration of Sevoflurane
Observational model: Cohort
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        Patients ≥ 65 years scheduled for elective non-cardiac surgery requiring general
        anesthesia.
      
Keywords: Frailty; Electroencephalography; Pre operative; Alpha power