Pre-operative biomarkers and imaging tests as predictors of post-operative delirium in non-cardiac surgical patients: a systematic review.

BACKGROUND: Post-operative delirium (POD) is a common post-operative complication in elderly individuals and imposes a significant health and financial burden. Identifying predictive biomarkers may help understand the pathophysiology of POD. Our objective is to summarize the evidence of pre-operative biomarkers and imaging tests to predict POD in patients undergoing non-cardiac surgery. METHODS: A systematic search of English language articles in MEDLINE, EMBASE, Cochrane Database, PsychINFO, PubMed and ClinicalTrials. Gov up to January 2018 was performed. Studies that used biomarkers or imaging tests to predict POD and a validated POD assessment tool were included. Animal studies, paediatric, cardiac and intracranial surgery were excluded. Risk of bias was assessed using the Quality In Prognosis Study tool. RESULTS: Thirty-four prospective cohort studies involving 4424 patients were included. Nineteen studies described serum tests [Interleukin-6, Insulin-like Growth Factor 1, C-Reactive Protein (CRP), cholinesterases, apolipoprotein-E genotype, leptin, hypovitaminosis, hypoalbuminaemia, gamma-amino butyric acid], 10 described cerebral-spinal fluid tests (monoamine precursor, melatonin, acute phase proteins, S100B and neurofibrillary tangles), and 5 described imaging tests. Two studies had high risk of bias due to unclear outcome measurement and study participation. CRP was significantly associated with POD in 5 studies. Other biomarkers were either examined by only a single study or two or more studies with conflicting results. CONCLUSION: CRP is the most promising biomarker associated with POD. However, we are still in the early stages in identifying biomarkers and imaging tests that may further understanding of the pathophysiology of POD.

Patient preference survey: are patients willing to delay surgery if obstructive sleep apnea is suspected?

BACKGROUND: Screening and optimizing patients for OSA in the perioperative period may reduce postoperative complications. However, sleep studies can be difficult to obtain before surgery. Previous surveys reported that the majority of sleep physicians would delay surgery to diagnose and manage OSA, but most anesthesiologists would not. While disagreements exist, the importance of shared decision making and patient preferences have never been studied on this topic. It is unknown whether patients with suspected OSA, when given information about OSA, would be willing to delay surgery to diagnose and manage their condition preoperatively. METHODS: This study consisted of a self-administered questionnaire that surveyed patients, patient relatives, or any accompanying members. The survey was conducted in the preoperative clinic or in the perioperative patient and family waiting area at two hospitals in Canada and in the United States. A hypothetical scenario was used: participants were given information about OSA, and asked about their preferences regarding preoperative management should they be at risk for OSA in the setting of pending elective surgery. The objective of this study was to determine whether respondents preferred to 1) proceed with surgery as planned, 2) delay surgery to ensure the medical condition of OSA is diagnosed and optimized, or 3) let his/her physician decide. RESULTS: The final survey contained 19 questions and the survey was conducted from June 2016 to September 2016. Four hundred and seventy-three surveys were collected. Forty-four percent of respondents, when given information about OSA, preferred to delay surgery pending a sleep study and treatment. Forty percent of respondents who preferred to delay surgery would tolerate delaying up to two months. CONCLUSION: Increasing emphasis and significant value has been placed on shared-decision making between patients and physicians. Educating patients about the risks of OSA and incorporating patient preferences into the perioperative management of OSA may be warranted.

Sleep-Disordered Breathing, Postoperative Delirium, and Cognitive Impairment.

Sleep-disordered breathing (SDB) is highly prevalent in the general population and has been associated with cognitive impairment in older individuals. Delirium is an acute decline in cognitive function and attention that often occurs after surgery, especially in older individuals. Several recent studies suggest an association between SDB and postoperative delirium. The aim of this systematic review is to examine the current literature on SDB, postoperative delirium, and cognitive impairment and to discuss the pathophysiology and perioperative considerations. A literature search was performed of Medline (1946-2016), Medline In-Process (June 2016), Embase (1947-2016), Cochrane Central Register of Controlled Trials (May 2016), and Cochrane Database of Systematic Reviews (2005 to June 2016). Inclusion criteria for studies were (1) polysomnography confirmed SDB; (2) postoperative delirium or cognitive impairment confirmed by a validated diagnostic tool; and (3) publications in the English language. All study designs including randomized controlled trials and observational studies were included. The literature search identified 2 studies on SDB and postoperative delirium, 15 studies on SDB and cognitive impairment, and 5 studies on the effect of continuous positive airway pressure on cognitive impairment and delirium in older individuals. SDB was associated with cognitive impairment, and this systematic review revealed that SDB may be a risk factor for postoperative delirium, especially in older individuals. Although the pathophysiology of SDB and postoperative delirium is unclear and effective treatments for SDB to reduce the incidence of delirium have not been studied extensively, preliminary evidence suggests that continuous positive airway pressure therapy may lower the risk of delirium. Health care professionals need to be aware that undiagnosed SDB may contribute to postoperative delirium. Preoperative screening for SDB and strategies to reduce the risk for postoperative delirium may be helpful in older individuals. Further studies are needed to clarify the relationship between SDB and postoperative delirium and elucidate the pathophysiology of postoperative delirium through SDB.