title: Association between frailty, cerebral oxygenation and adverse post-operative outcomes in elderly patients undergoing non-cardiac surgery: An observational pilot study.
abstract: OBJECTIVE
  Although both frailty and low cerebral oxygen saturation increase the risk of post-operative complications, their relationship is yet to be investigated. The purpose of this observational study was to investigate the association between frailty, intraoperative cerebral oxygen saturation and post-operative complications in elderly patients undergoing non-cardiac surgery.
  
  
  METHODS
  After approval from the Institutional Review Board, 25 elderly patients (>65 years) undergoing non-cardiac major surgery were included in this study. Pre-operatively, all included patients were assessed for frailty and classified into frail and non-frail groups. All patients had routine intraoperative monitors, and a cerebral oximeter applied during anaesthesia. The 'intraoperative' anaesthesiologist and the post-operative study investigator were blinded to cerebral oximeter readings throughout the study. The incidence of significant intraoperative cerebral oxygen desaturation, adverse post-operative outcomes and length of hospital stay were compared. Statistical significance was defined as a value of P < 0.05.
  
  
  RESULTS
  We found that the frail group had more intraoperative cerebral desaturation (odds ratio [OR] [95% confidence interval [CI]]: 1.75 [1.11-2.75]) and longer median (interquartile range) length of hospital stay compared to the non-frail group (13.5 days [8.75-27.5] and 8 days [6-11], respectively). Furthermore, in patients with a low-baseline cerebral oxygen saturation (<55%), intraoperative cerebral desaturation (OR [95% CI]: 2.10 [1.00-4.42]), adverse post-operative outcomes (OR [95% CI]: 1.80 [1.00-3.23]) and median (interquartile range) length of hospital stay (15 days [9-31.5] vs. 9 days [6.25-13.75], P = 0.04) were significantly higher compared to subjects with higher baseline (≥55%) cerebral oxygen saturation.
  
  
  CONCLUSIONS
  Frail patients have more intraoperative cerebral desaturation and longer lengths of hospital stay compared to non-frail patients.
authors.affiliation: Department of Anaesthesiology, General Hospital, Singapore.
authors.forename: Shariq Ali
authors.initials: SA
authors.lastname: Khan
authors.affiliation: Department of Anaesthesiology, General Hospital, Singapore.
authors.forename: Henry Wenjie
authors.initials: HW
authors.lastname: Chua
authors.affiliation: Department of Anaesthesiology, General Hospital, Singapore.
authors.forename: Premila
authors.initials: P
authors.lastname: Hirubalan
authors.affiliation: Department of Anaesthesiology, Sri Ramachandra Medical College and Research Institute, Chennai, Tamil Nadu, India.
authors.forename: Ranjith Baskar
authors.initials: RB
authors.lastname: Karthekeyan
authors.affiliation: Department of Anaesthesiology, General Hospital, Singapore.
authors.forename: Harikrishnan
authors.initials: H
authors.lastname: Kothandan
keywords: Cerebral oxygenation; frailty; non-cardiac surgery; post-operative outcome