Optimised Anaesthesia to Reduce Post Operative Cognitive Decline (POCD) in Older Patients Undergoing Elective Surgery, a Randomised Controlled Trial

Background The study determined the one year incidence of post operative cognitive decline (POCD) and evaluated the effectiveness of an intra-operative anaesthetic intervention in reducing post-operative cognitive impairment in older adults (over 60 years of age) undergoing elective orthopaedic or abdominal surgery. Methods and Trial Design The design was a prospective cohort study with a nested randomised, controlled intervention trial, using intra-operative BiSpectral index and cerebral oxygen saturation monitoring to enable optimisation of anaesthesia depth and cerebral oxygen saturation in older adults undergoing surgery. Results In the 52 week prospective cohort study (192 surgical patients and 138 controls), mild (?2 = 17.9 p<0.0001), moderate (?2 = 7.8 p = 0.005) and severe (?2 = 5.1 p = 0.02) POCD were all significantly higher after 52 weeks in the surgical patients than among the age matched controls. In the nested RCT, 81 patients were randomized, 73 contributing to the data analysis (34 intervention, 39 control). In the intervention group mild POCD was significantly reduced at 1, 12 and 52 weeks (Fisher’s Exact Test p = 0.018, ?2 = 5.1 p = 0.02 and ?2 = 5.9 p = 0.015), and moderate POCD was reduced at 1 and 52 weeks (?2 = 4.4 p = 0·037 and ?2 = 5.4 p = 0.02). In addition there was significant improvement in reaction time at all time-points (Vigilance Reaction Time MWU Z = ?2.1 p = 0.03, MWU Z = ?2.7 p = 0.004, MWU Z = ?3.0 p = 0.005), in MMSE at one and 52 weeks (MWU Z = ?2.9 p = 0.003, MWU Z = ?3.3 p = 0.001), and in executive function at 12 and 52 weeks (Trail Making MWU Z = ?2.4 p = .0.018, MWU Z = ?2.4 p = 0.019). Conclusion POCD is common and persistent in older adults following surgery. The results of the nested RCT indicate the potential benefits of intra-operative monitoring of anaesthetic depth and cerebral oxygenation as a pragmatic intervention to reduce post-operative cognitive impairment

Incidence of and factors associated with perioperative cardiac arrest within 24 hours of anesthesia for emergency surgery

Visith Siriphuwanun,1 Yodying Punjasawadwong,1 Worawut Lapisatepun,1 Somrat Charuluxananan,2 Ketchada Uerpairojkit2 1Department of Anesthesiology, Faculty of Medicine, Chiang Mai University, Mueang District, Chiang Mai, Thailand; 2Department of Anesthesiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand Purpose: To determine the incidence of and factors associated with perioperative cardiac arrest within 24 hours of receiving anesthesia for emergency surgery. Patients and methods: This retrospective cohort study was approved by the ethical committee of Maharaj Nakorn Chiang Mai Hospital, Thailand. We reviewed the data of 44,339 patients receiving anesthesia for emergency surgery during the period from January 1, 2003 to March 31, 2011. The data included patient characteristics, surgical procedures, American Society of Anesthesiologists (ASA) physical status classification, anesthesia information, location of anesthesia performed, and outcomes. Data of patients who had received topical anesthesia or monitoring anesthesia care were excluded. Factors associated with cardiac arrest were identified by univariate analyses. Multiple regressions for the risk ratio (RR) and 95% confidence intervals (CI) were used to determine the strength of factors associated with cardiac arrest. A forward stepwise algorithm was chosen at a P-value &lt;0.05. Results: The incidence (within 24 hours) of perioperative cardiac arrest in patients receiving anesthesia for emergency surgery was 163 per 10,000. Factors associated with 24-hour perioperative cardiac arrest in emergency surgery were age of 2 years or younger (RR =1.46, CI =1.03&ndash;2.08, P=0.036), ASA physical status classification of 3&ndash;4 (RR =5.84, CI =4.20&ndash;8.12, P&lt;0.001) and 5&ndash;6 (RR =33.98, CI =23.09&ndash;49.98, P&lt;0.001), the anatomic site of surgery (upper intra-abdominal, RR =2.67, CI =2.14&ndash;3.33, P&lt;0.001; intracranial, RR =1.74, CI =1.35&ndash;2.25, P&lt;0.001; intrathoracic, RR =2.35, CI =1.70&ndash;3.24, P&lt;0.001; cardiac, RR =3.61, CI =2.60&ndash;4.99, P&lt;0.001; and major vascular; RR =3.05, CI =2.22&ndash;4.18, P&lt;0.001), respiratory or cardiovascular comorbidities (RR =1.95, CI =1.60&ndash;2.38, P&lt;0.001 and RR =1.38, CI =1.11&ndash;1.72, P=0.004, respectively), and patients in shock prior to receiving anesthesia (RR =2.62, CI =2.07&ndash;3.33, P&lt;0.001). Conclusion: The perioperative incidence of cardiac arrest within 24 hours of anesthesia for emergency surgery was high and associated with multiple factors such as young age (&le;2 years old), cardiovascular and respiratory comorbidities, increasing ASA physical status classification, preoperative shock, and surgery site. Perioperative care providers, including surgeons, anesthesiologists, and nurses, should be prepared to manage promptly this high risk group of surgical patients. Keywords: risk factors, retrospective cohort, anesthetic care, perioperative cardiac arrest, emergency surger

Bispectral index for improving intraoperative awareness and early postoperative recovery in adults

Background:The use of clinical signs, or end‐tidal anaesthetic gas (ETAG), may not be reliable in measuring the hypnotic component of anaesthesia and may lead to either overdosage or underdosage resulting in adverse effects because of too deep or too light anaesthesia. Intraoperative awareness, whilst uncommon, may lead to serious psychological disturbance, and alternative methods to monitor the depth of anaesthesia may reduce the incidence of serious events. Bispectral index (BIS) is a numerical scale based on electrical activity in the brain. Using a BIS monitor to guide the dose of anaesthetic may have advantages over clinical signs or ETAG. This is an update of a review last published in 2014.Objectives:To assess the effectiveness of BIS to reduce the risk of intraoperative awareness and early recovery times from general anaesthesia in adults undergoing surgery.Search methods:We searched CENTRAL, MEDLINE, Embase, and Web of Science on 26 March 2019. We searched clinical trial registers and grey literature, and handsearched reference lists of included studies and related reviews.Selection criteria:We included randomized controlled trials (RCTs) and quasi‐RCTs in which BIS was used to guide anaesthesia compared with standard practice which was either clinical signs or end‐tidal anaesthetic gas (ETAG) to guide the anaesthetic dose. We included adult participants undergoing any type of surgery under general anaesthesia regardless of whether included participants had a high risk of intraoperative awareness. We included only studies in which investigators aimed to evaluate the effectiveness of BIS for its role in monitoring intraoperative depth of anaesthesia or potential improvements in early recovery times from anaesthesia.Data collection and analysis:Two review authors independently assessed studies for inclusion, extracted data, and assessed risk of bias. We assessed the certainty of evidence with GRADE.Main results:We included 52 studies with 41,331 participants; two studies were quasi‐randomized and the remaining studies were RCTs. All studies included participants undergoing surgery under general anaesthesia. Three studies recruited only participants who were at high risk of intraoperative awareness, whilst two studies specifically recruited an unselected participant group. We analysed the data according to two comparison groups: BIS versus clinical signs; and BIS versus ETAG. Forty‐eight studies used clinical signs as a comparison method, which included titration of anaesthesia according to criteria such as blood pressure or heart rate and, six studies used ETAG to guide anaesthesia. Whilst BIS target values differed between studies, all were within a range of values between 40 to 60.BIS versus clinical signs: We found low‐certainty evidence that BIS‐guided anaesthesia may reduce the risk of intraoperative awareness in a surgical population that were unselected or at high risk of awareness (Peto odds ratio (OR) 0.36, 95% CI 0.21 to 0.60; I2 = 61%; 27 studies; 9765 participants). However, events were rare with only five of 27 studies with reported incidences; we found that incidences of intraoperative awareness when BIS was used were three per 1000 (95% CI 2 to 6 per 1000) compared to nine per 1000 when anaesthesia was guided by clinical signs. Of the five studies with event data, one included participants at high risk of awareness and one included unselected participants, four used a structured questionnaire for assessment, and two used an adjudication process to identify confirmed or definite awareness.Early recovery times were also improved when BIS was used. We found low‐certainty evidence that BIS may reduce the time to eye opening by mean difference (MD) 1.78 minutes (95% CI ‐2.53 to ‐1.03 minutes; 22 studies; 1494 participants), the time to orientation by MD 3.18 minutes (95% CI ‐4.03 to ‐2.33 minutes; 6 studies; 273 participants), and the time to discharge from the postanaesthesia care unit (PACU) by MD 6.86 minutes (95% CI ‐11.72 to ‐2 minutes; 13 studies; 930 participants).BIS versus ETAG: Again, events of intraoperative awareness were extremely rare, and we found no evidence of a difference in incidences of intraoperative awareness according to whether anaesthesia was guided by BIS or by ETAG in a surgical population at unselected or at high risk of awareness (Peto OR 1.13, 95% CI 0.56 to 2.26; I2 = 37%; 5 studies; 26,572 participants; low‐certainty evidence). Incidences of intraoperative awareness were one per 1000 in both groups. Only three of five studies reported events, two included participants at high risk of awareness and one included unselected participants, all used a structured questionnaire for assessment and an adjudication process to identify confirmed or definite awareness.One large study (15,452 participants) reported a reduced time to discharge from the PACU by a median of three minutes less, and we judged the certainty of this evidence to be low. No studies measured or reported the time to eye opening and the time to orientation.Certainty of the evidence: We used GRADE to downgrade the evidence for all outcomes to low certainty. The incidence of intraoperative awareness is so infrequent such that, despite the inclusion of some large multi‐centre studies in analyses, we believed that the effect estimates were imprecise. In addition, analyses included studies that we judged to have limitations owing to some assessments of high or unclear bias and in all studies, it was not possible to blind anaesthetists to the different methods of monitoring depth of anaesthesia.Studies often did not report a clear definition of intraoperative awareness. Time points of measurement differed, and methods used to identify intraoperative awareness also differed and we expected that some assessment tools were more comprehensive than others.Authors' conclusions:Intraoperative awareness is infrequent and, despite identifying a large number of eligible studies, evidence for the effectiveness of using BIS to guide anaesthetic depth is imprecise. We found that BIS‐guided anaesthesia compared to clinical signs may reduce the risk of intraoperative awareness and improve early recovery times in people undergoing surgery under general anaesthesia but we found no evidence of a difference between BIS‐guided anaesthesia and ETAG‐guided anaesthesia. We found six studies awaiting classification and two ongoing studies; inclusion of these studies in future updates may increase the certainty of the evidence