Anesthetic Titration Research Articles

Depth of anesthesia monitoring in Norway-A web-based survey.

The bispectral index (BIS) monitor is the most frequently used electroencephalogram (EEG)-based depth of anesthesia (DoA) technology in Norwegian hospitals. However, there is limited knowledge regarding the extent and clinical impact of its use and how anesthesiologists and nurse anesthetists use the information provided by the DoA monitors in their clinical practice. This cross-sectional survey on the use of DoA monitors in Norway used a web-based questionnaire distributed to anesthesia personnel in all hospitals in Norway. Participation was voluntary and anonymized, and the web form could not track IP sources or respondents' locations. Three hundred and ninety-one nurse anesthetists (n = 324) and anesthesiologists (n = 67) responded. Among the EEG-based DoA monitoring tools, BIS was most often used to observe and assess patients' DoA (98%). Raw EEG waveform analysis (10%), EEG-spectrogram (9%), and suppression rate (10%) were seldom used. Twenty-seven percent of the anesthesia personnel were able to recognize a burst suppression pattern on EEG and its significance. Fifty-eight percent of the respondents considered clinical observations more reliable than BIS. Almost all respondents reported adjusting anesthetic dosage based on the BIS index values (80%). However, the anesthetic dose was more often increased (90%) because of high BIS index values than lowered (55%) because of low BIS index values. Despite our respondents' extensive use of DoA monitoring, the anesthesia personnel in our survey did not use all the information and the potential to guide the titration of anesthetics the DoA monitors provide. Thus, anesthesia personnel could generally benefit from increased knowledge of how EEG-based DoA monitoring can be used to assess and determine individual patients' need for anesthetic medication.

Alternate Electrode Placements to Facilitate Frontal Electroencephalography Monitoring in Anesthetized and Critically Ill Patients.

Frontal electroencephalography (EEG) monitoring can be useful in guiding the titration of anesthetics, but it is not always feasible to place electrodes in the standard configuration in some circumstances, including during neurosurgery. This study compares 5 alternate configurations of the Masimo Sedline Sensor. Ten stably sedated patients in the intensive care unit were recruited. Frontal EEG was monitored in the standard configuration (bifrontal upright) and 5 alternate configurations: bifrontal inverse, infraorbital, lateral upright, lateral inverse, and semilateral. Average power spectral densities (PSDs) with 95% CIs in the alternate configurations were compared to PSDs in the standard configuration. Two-one-sided-testing with Wilcoxon signed-rank tests assessed equivalence in the spectral edge frequency (SEF-95), EEG power, and relative delta (0.5 to 3.5Hz), alpha (8 to 12Hz), and beta (20 to 30Hz) power between each alternate and standard configurations. After the removal of unanalyzable tracings, 7 patients were included for analysis in the infraorbital configuration and 9 in all other configurations. In the lateral upright and lateral inverse configurations, PSDs significantly differed from the standard configuration within the 15 to 20Hz band. The greatest decrease in EEG power was in the lateral inverse configuration (median: -97dB; IQR: -130, -62dB). The largest change in frequency distribution of EEG power was in the infraorbital configuration; median SEF-95 change of -1.4Hz (IQR: -2.8, 0.7Hz), median relative delta power change of +7.3% (IQR: 1.4%, 7.9%), and median relative alpha power change of -0.6% (IQR: -5.7%, 0.0%). These 5 alternate Sedline electrode configurations are suitable options for monitoring frontal EEG when the standard configuration is not possible.

EEG‐guided anesthetic titration and perioperative neurocognitive disorders

AbstractBackgroundPostoperative delirium (POD) is a serious complication of surgery associated with prolonged hospitalisation, long‐term cognitive decline, dementia and mortality. There is increasing evidence that electroencephalography (EEG) monitoring may reduce the incidence of POD, however, the best method for achieving this is unclear.MethodThis presentation will present the results of a multicentre randomised clinical trial of 515 at‐risk patients undergoing major surgery from 8 centres in 3 countries who were assessed for POD for 5 days postoperatively. They also underwent cognitive screening at baseline, discharge, 30 days and one year postoperatively. Patients were assigned to light or deep anaesthesia. Additionally, this presentation will consider a meta‐analysis of available studies investigating EEG monitoring to prevent delirium and outline the importance of EEG spectrogram interpretation as part of EEG monitoring and consequent anesthetic titration when using this technique to reduce or prevent POD.ResultThe incidence of POD was lower (19%) in the light anesthesia group compared with the deep anesthesia group (28%) (OR 0.58 (95% CI 0.38 to 0.88), P = 0.010). Meta‐analysis results were fragile and depended on inclusion criteria of studies. Interpretation of EEG spectrograms is a developing field, but adds significant, critical information.ConclusionEEG monitoring looks to be a possible method for preventing POD and long‐term complications. EEG spectrogram interpretation will likely add critical information to enhance this technique.

Protocol for a randomized controlled trial to reduce pediatric anesthesia emergence delirium by titration of sevoflurane anesthesia using brain function monitoring

BackgroundEmergence agitation or emergence delirium is a common complication of unknown etiology in pediatric anesthesia. Pediatric anesthesia emergence delirium (PAED) has been reported most commonly in younger children and may occur in about 30% of children up to 5–6 years old. Exposure to anesthetic agents may contribute to PAED, and we hypothesized that a management strategy to minimize exposure to volatile anesthetics may reduce PAED. Electroencephalography (EEG) signatures captured and displayed by brain function monitors during anesthesia change with concentration of sevoflurane and level of unconsciousness, and these EEG signatures may be used to inform titration of anesthetics.MethodsA single-center, parallel-group, two-arm, superiority trial with a 1:1 allocation ratio will be performed to compare the incidence of PAED following standard sevoflurane anesthesia (maintained at 1.0MAC) and EEG-guided anesthesia (minimum concentration to sustain surgical anesthesia as determined by monitoring of EEG signatures). Participants between 1 and 6 years of age undergoing surgical procedures involving minimal postoperative pain will be randomly assigned to receive standard (n = 90) or EEG-guided (n = 90) anesthesia. PAED score will be assessed by a blinded observer in the PACU on arrival and after 5, 10, 15, and 30 min.DiscussionAnesthesia management with proactive use of brain function monitoring is expected to reduce exposure to sevoflurane without compromising surgical anesthesia. We expect this reduced exposure should help prevent PAED. Routinely administering what may be considered standard levels of anesthetic such as 1.0 MAC sevoflurane may be excessive and potentially associated with unfavorable sequelae such as PAED.Trial registrationJapan Registry of Clinical Trials (jRCT) jRCTs032210248. Prospectively registered on 17 August 2021.

Pro-Con Debate: Electroencephalography-Guided Anesthesia for Reducing Postoperative Delirium.

Postoperative delirium (POD) has significant implications on morbidity, mortality, and health care expenditures. Monitoring electroencephalography (EEG) to adjust anesthetic management has gained interest as a strategy to mitigate POD. In this Pro-Con commentary article, the pro side supports the use of EEG to reduce POD, citing an empiric reduction in POD with processed EEG (pEEG)-guided general anesthesia found in several studies and recent meta-analysis. The Electroencephalography Guidance of Anesthesia to Alleviate Geriatric Syndromes (ENGAGES) trial is the exception to this, and issues with methods and achieved depths are discussed. Meanwhile, the Con side advocates that the use of EEG to reduce POD is not yet certain, citing that there is a lack of evidence that associations between anesthetic depth and POD represent causal relationships. The Con side also contends that the ideal EEG signatures to guide anesthetic titration are currently unknown, and the potential benefits of reduced anesthesia levels may be outweighed by the risks of potentially insufficient anesthetic administration. As the public health burden of POD increases, anesthesia clinicians will be tasked to consider interventions to mitigate risk such as EEG. This Pro-Con debate will provide 2 perspectives on the evidence and rationales for using EEG to mitigate POD.

Pro-Con Debate: Should All General Anesthesia Be Done Using Target-Controlled Propofol Infusion Guided by Objective Monitoring of Depth of Anesthesia?

In this Pro-Con commentary article, we discuss whether all general anesthesia should be done using target-controlled propofol anesthesia guided by monitoring of depth of anesthesia. This is an ongoing debate since more than 25 years, representing a scientific, cultural as well as geographical divide in the anesthesia community. The Pro side argues that total intravenous anesthesia causes less postoperative nausea and higher patient satisfaction than anesthesia using volatile anesthetics. Target-controlled infusion (TCI) of anesthetic agents allows for better titration of intravenous anesthesia using pharmacokinetic models. Processed EEG monitors, such as bispectral index monitoring, allows for better assessing the effect of TCI anesthesia than solely assessment of clinical parameters, such as ECG or blood pressure. The combination of TCI propofol and objective depth of anesthesia monitoring allows creating a pharmacokinetic-pharmacodynamic profile for each patient. Finally, anesthesia using volatile anesthetics poses health risks for healthcare professionals and contributes to greenhouse effect. The Con side argues that for procedures accompanied with ischemia and reperfusion injury of an organ or tissue and for patients suffering from a severe inflammation' the use of volatile anesthetics might well have its advantages above propofol. In times of sudden shortage of drugs, volatile anesthetics can overcome the restriction in the operating theater or even on the intensive care unit, which is another advantage. Volatile anesthetics can be used for induction of anesthesia when IV access is impossible, end-tidal measurements of volatile anesthetic concentration allows confirmation that patients receive anesthetics. Taking environmental considerations into account, both propofol and volatile anesthetics bear certain harm to the environment, be it as waste product or as greenhouse gases. The authors therefore suggest to carefully considering advantages and disadvantages for each patient in its according environment. A well-balanced choice based on the available literature is recommended. The authors recommend careful consideration of advantages and disadvantages of each technique when tailoring an anesthetic to meet patient needs. Where appropriate, anesthesia providers are encouraged to account for unique features of anesthetic drug behavior, patient-reported and observed postoperative outcomes, and economic and environmental considerations when choosing any of the 2 described techniques.

Comment on the Need to Fill a Gap in the Assessment of Neurological Status Before Elective Surgery.

Comment on the Need to Fill a Gap in the Assessment of Neurological Status Before Elective Surgery.

Faktori rizika za nastanak postoperativnog delirijuma

The occurrence of postoperative delirium (POD) has been recognized in recent decades as an important clinical syndrome, especially in elderly patients undergoing surgical treatment. The aim of this review was to examine the preoperative, intraoperative and postoperative factors that can lead to the occurrence of POD. The risk factors for developing POD are numerous, and most importantly, many can be modified. Some of the most significant risk factors for the occurrence of POD are older age, alcohol abuse, preoperatively worse functional and cognitive status, presence of depression and dementia. A higher incidence of POD was observed in patients undergoing more complex surgical procedures such as cardiac, vascular and orthopedic hip fracture operations. It was observed that after emergency surgical procedures POD occurs 1.5 to 3 times more often than during elective planned surgical procedures. Also, intraoperative bleeding and the application of transfusion were identified as significant risk factors for the occurrence of POD. In order to avoid cognitive deficits caused by longer exposure to anesthesia, research has shown that anesthetic titration by monitoring the bispectral index, as well as evoked auditory potentials, can reduce excessive exposure to anesthetics and thus reduce the risk of postoperative cognitive dysfunction. Knowledge of risk factors and identification of patients at increased risk are the basis of a strategy for the prevention of this syndrome. Current evidence suggests that perioperative avoidance of benzodiazepine use as well as adequate perioperative pain control are key measures to reduce the risk of POD.

Balancing the risks and benefits of anesthetics in status epilepticus

PurposeAccording to international guidelines, status epilepticus refractory to first- and second-line antiseizure medication should be treated with anesthetics. Therefore, continuously delivered intravenous midazolam, propofol, or barbiturates are recommended as third-line therapy. While electroencephalographically (EEG)-controlled titration of anesthetics to seizure termination or to the emergence of an EEG burst-suppression pattern makes sense, evidence of the efficacy and tolerability of such third-line treatment is limited and concerns regarding the risks of anesthesia remain. The lack of treatment alternatives and persistent international discord reflecting contradictory results from some studies leave clinicians on their own when deciding to escalate treatment.In this conference-accompanying narrative review, we highlight the challenges of EEG-monitored third-line treatment and discuss recent studies that examined earlier administration of anesthetics. ResultsBased on the literature, maintaining continuous burst suppression is difficult despite the constant administration of anesthetics, and the evidence for burst suppression as an adequate surrogate target is limited by methodological shortcomings as acknowledged by international guidelines. In our Swiss cohort including 102 patients with refractory status epilepticus, burst suppression as defined by the American Clinical Neurophysiology Society's Critical Care EEG Terminology 2021 was established in only 21%. Besides case reports suggesting that rapid but short-termed anesthesia can be sufficient to permanently stop seizures, a study including 205 patients revealed that anesthesia as second-line treatment was associated with a shorter median duration of status epilepticus (0.5 versus 12.5 days, p < 0.001), median ICU (2 versus 5.5 days, p < 0.001) and hospital stay (8 versus 17 days, p < 0.001) with equal rates of complications when compared to anesthesia as third-line treatment. ConclusionsRecent investigations have led to important findings and new insights regarding the use of anesthetics in refractory status epilepticus. However, numerous methodological limitations and remaining questions need to be considered when it comes to the translation into clinical practice, and, in consequence, call for prospective randomized studies.This paper was presented at the 8th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures held in September 2022.

Burst Suppression During General Anesthesia and Postoperative Outcomes: Mini Review.

In the last decade, burst suppression has been increasingly studied by many to examine whether it is a mechanism leading to postoperative cognitive impairment. Despite a lack of consensus across trials, the current state of research suggests that electroencephalogram (EEG) burst suppression, duration and EEG emergence trajectory may predict postoperative delirium (POD). A mini literature review regarding evidence about burst suppression impact and susceptibilities was conducted, resulting in conflicting studies. Primarily, studies have used different algorithm values to replace visual burst suppression examination, although many studies have since emerged showing that algorithms underestimate burst suppression duration. As these methods may not be interchangeable with visual analysis of raw data, it is a potential factor for the current heterogeneity between data. Even though additional research trials incorporating the use of raw EEG data are necessary, the data currently show that monitoring with commercial intraoperative EEG machines that use EEG indices to estimate burst suppression may help physicians identify burst suppression and guide anesthetic titration during surgery. These modifications in anesthetics could lead to preventing unfavorable outcomes. Furthermore, some studies suggest that brain age, baseline impairment, and certain medications are risk factors for burst suppression and postoperative delirium. These patient characteristics, in conjunction with intraoperative EEG monitoring, could be used for individualized patient care. Future studies on the feasibility of raw EEG monitoring, new technologies for anesthetic monitoring and titration, and patient-associated risk factors are crucial to our continued understanding of burst suppression and postoperative delirium.

Comparison between continuous rate infusion and target-controlled infusion of propofol in dogs: a randomized clinical trial

ObjectiveTo compare a propofol continuous rate infusion (CRI) with a target-controlled infusion (TCI) in dogs. Study designRandomized prospective double-blinded clinical study. AnimalsA total of 38 healthy client-owned dogs. MethodsDogs premedicated intramuscularly with acepromazine (0.03 mg kg–1) and an opioid (pethidine 3 mg kg–1, morphine 0.2 mg kg–1 or methadone 0.2 mg kg–1) were allocated to P-CRI group (propofol 4 mg kg–1 intravenously followed by CRI at 0.2 mg kg–1 minute–1), or P-TCI group [propofol predicted plasma concentration (Cp) of 3.5 μg mL–1 for induction and maintenance of anaesthesia via TCI]. Plane of anaesthesia, heart rate, respiratory rate, invasive blood pressure, oxygen haemoglobin saturation, end-tidal carbon dioxide and body temperature were monitored by an anaesthetist blinded to the group. Numerical data were analysed by unpaired t test or Mann–Whitney U test, one-way analysis of variance and Dunnett’s post hoc test. Categorical data were analysed with Fisher’s exact test. Significance was set for p < 0.005. ResultsOverall, propofol induced a significant incidence of relative hypotension (mean arterial pressure 20% below baseline, 45%), apnoea (71%) and haemoglobin desaturation (65%) at induction of anaesthesia, with a higher incidence of hypotension and apnoea in the P-CRI than P-TCI group (68% versus 21%, p = 0.008; 84% versus 58%, p = 0.0151, respectively). Propofol Cp was significantly higher at intubation in the P-CRI than P-TCI group (4.83 versus 3.5 μg mL–1, p < 0.0001), but decreased during infusion, while Cp remained steady in the P-TCI group. Total propofol administered was similar between groups. Conclusions and clinical relevanceBoth techniques provided a smooth induction of anaesthesia but caused a high incidence of side effects. Titration of anaesthesia with TCI caused fewer fluctuations in Cp and lower risk of hypotension compared with CRI.

Evaluating the role of Smartpilot® view assisted target-controlled infusion anesthesia during intracranial mass surgery: A comparative retrospective study with bispectral index-guided standard anesthesia

Background/Aim: Neuroanesthesia necessitates the control of both systemic and cerebral hemodynamics, the prevention of intracranial pressure increase, knowledge of anesthetics’ cerebral effects, and early neurological recovery. The titration of anesthetics becomes crucial to optimize the appropriate level of anesthesia required for surgery while reducing postoperative neurological consequences. Smartpilot® View (SPV) is a new decision support system that uses pharmacologic models to optimize anesthetic depth and improve patient outcomes. The goal of this study was to compare the effectiveness of SPV with standard BIS-guided anesthesia administration in terms of intraoperative hemodynamic stabilization, anesthetic consumption, and postoperative recovery times during intracranial mass surgery. Methods: Following ethics committee approval, the records of the patients who underwent elective supratentorial craniotomy between November 15, 2017 and March 15, 2018 were reviewed retrospectively. The demographics of the patients, anesthesia and surgery times, eye opening and extubation times, time to reach an Aldrete score of 9 and anesthetic consumptions were compared between those who were monitored with SPV in addition to BIS (SPV Group) and those who were monitored with solely BIS for standard anesthetic follow-up (BIS Group). Results: A total of 139 subjects were analyzed (SPV (n=71), BIS (n=68)). Hemodynamic responses to induction and intubation were more pronounced in the BIS group (P<0.05). Time until eye opening and extubation were 3.6 (2.4) versus 6.06 (1.63) minutes and 5.76 (1.3) versus 9.16 (1.0) minutes in the SPV and BIS groups (P<0.001). In the SPV Group, it took much less time to achieve an Aldrete score of 9 or above (P<0.001). Total consumed amount of both propofol and remifentanil were significantly lower in the SPV group (P<0.001). Conclusion: Use of SPV compared to BIS-guided routine anesthesia follow-up improved titration and consumption of anesthetic drugs, thereby facilitating the early recovery process in patients who underwent intracranial mass surgery.

Raw and processed electroencephalography in modern anesthesia practice: a brief primer on select clinical applications.

The evidence supporting the intraoperative use of processed electroencephalography (pEEG) monitoring to guide anesthetic delivery is growing rapidly. This article reviews the key features of electroencephalography (EEG) waveforms and their clinical implications in select patient populations and anesthetic techniques. The first patient topic reviewed is the vulnerable brain. This term has emerged as a description of patients who may exhibit increased sensitivity to anesthetics and/or may develop adverse neurocognitive effects following anesthesia. pEEG monitoring of patients who are known to have or are suspected of having vulnerable brains, with focused attention on the suppression ratio, alpha band power, and pEEG indices, may prove useful. Second, pEEG monitoring along with vigilant attention to anesthetic delivery may minimize the risk of intraoperative awareness when administering a total intravenous anesthesia in combination with a neuromuscular blockade. Third, we suggest that processed EEG monitoring may play a role in anesthetic and resuscitative management when adverse changes in blood pressure occur. Fourth, pEEG monitoring can be used to better identify anesthesia requirements and guide anesthetic titration in patients with known or suspected substance use.

Developing a Real-Time Electroencephalogram-Guided Anesthesia-Management Curriculum for Educating Residents: A Single-Center Randomized Controlled Trial.

Different anesthetic drugs and patient factors yield unique electroencephalogram (EEG) patterns. Yet, it is unclear how best to teach trainees to interpret EEG time series data and the corresponding spectral information for intraoperative anesthetic titration, or what effect this might have on outcomes. We developed an electronic learning curriculum (ELC) that covered EEG spectrogram interpretation and its use in anesthetic titration. Anesthesiology residents at a single academic center were randomized to receive this ELC and given spectrogram monitors for intraoperative use versus standard residency curriculum alone without intraoperative spectrogram monitors. We hypothesized that this intervention would result in lower inhaled anesthetic administration (measured by age-adjusted total minimal alveolar concentration [MAC] fraction and age-adjusted minimal alveolar concentration [aaMAC]) to patients ≥60 old during the postintervention period (the primary study outcome). To study this effect and to determine whether the 2 groups were administering similar anesthetic doses pre- versus postintervention, we compared aaMAC between control versus intervention group residents both before and after the intervention. To measure efficacy in the postintervention period, we included only those cases in the intervention group when the monitor was actually used. Multivariable linear mixed-effects modeling was performed for aaMAC fraction and hospital length of stay (LOS; a non-prespecified secondary outcome), with a random effect for individual resident. A multivariable linear mixed-effects model was also used in a sensitivity analysis to determine if there was a group (intervention versus control group) by time period (post- versus preintervention) interaction for aaMAC. Resident EEG knowledge difference (a prespecified secondary outcome) was compared with a 2-sided 2-group paired t test. Postintervention, there was no significant aaMAC difference in patients cared for by the ELC group (n = 159 patients) versus control group (N = 325 patients; aaMAC difference = -0.03; 95% confidence interval [CI], -0.09 to 0.03; P =.32). In a multivariable mixed model, the interaction of time period (post- versus preintervention) and group (intervention versus control) led to a nonsignificant reduction of -0.05 aaMAC (95% CI, -0.11 to 0.01; P = .102). ELC group residents (N = 19) showed a greater increase in EEG knowledge test scores than control residents (N = 20) from before to after the ELC intervention (6-point increase; 95% CI, 3.50-8.88; P < .001). Patients cared for by the ELC group versus control group had a reduced hospital LOS (median, 2.48 vs 3.86 days, respectively; P = .024). Although there was no effect on mean aaMAC, these results demonstrate that this EEG-ELC intervention increased resident knowledge and raise the possibility that it may reduce hospital LOS.

Reducing Perioperative Neurocognitive Disorders (PND) Through Depth of Anesthesia Monitoring: A Critical Review.

General anesthesia has been administered for over 150 years, and in that time, has become progressively safer. Improvements in outcomes have been driven by multiple advances, including the use of non-invasive monitors to assess cardiovascular and respiratory status. More recent advances have included the development and use of monitors to measure neurologic status by means of “processed” electroencephalography (pEEG), wherein the frontal EEG signal is analyzed by proprietary algorithms to produce a dimensionless number (scaled from 0 to 100), wherein low values are associated with deepening levels of sedation that progresses to loss of consciousness. Such monitors have been shown to enable anesthetic titration so as to expedite emergence and early recovery, and their use is advocated for the prevention of intraoperative awareness in the setting of administration of total intravenous anesthesia and neuromuscular blockade. Whether their use can minimize, or prevent, longer term adverse events is a matter of debate. In this narrative review of the most recent literature, we provide an assessment on the use of pEEG monitors in the prevention of a notable, and important, postoperative adverse outcome – delirium – in elderly patients. As we will discuss, the existing data do not support its routine use for the prevention of postoperative delirium in this, or any other, patient population.

Anaesthesia challenges in Wilson’s disease with multisystem involvement

Wilson’s disease is a rare genetic disorder with a prevalence rate of 1:10000-1:30000. It is a multi- system disorder with a defect in the copper transporter protein; thereby resulting in extortionate copper deposition in organs of the body; mainly liver, brain and cornea. Osteo-muscular involvement may also be seen, presenting as dystonia and muscle rigidity. The case discussed below is that of a 13 year old patient, ASA III E, diagnosed with Wilson’s disease 7 years back and now is posted for emergency tracheostomy under anaesthesia in view of chest rigidity, difficulty in breathing and repeated episodes of bronchospasm. The patient presented in late stage of the disorder with associated derangements of multiple systems of the body. This case report provides details of successful administration of Anaesthesia to a patient with Wilson's in late phase. The management protocol can be used as a guide in other surgeries of patients with this disorder, as precise titration of anaesthesia is needed.

Seen and Ignored: Are We Undermining Studies of Brain Health Interventions Before We Start?

Seen and Ignored: Are We Undermining Studies of Brain Health Interventions Before We Start?

Titration of sevoflurane anesthesia to optimize the time to regain airway reflexes in patients undergoing elective surgery: A randomized clinical trial comparing desflurane and sevoflurane anesthesia

Desflurane has adverse environmental effects, but has clinical advantages to speed emergence and return of protective airway reflexes compared with sevoflurane. We hypothesized that weaning of the inspired sevoflurane during the final 15minutes of surgery would eliminate differences in airway reflex recovery between these agents. After obtaining IRB approval and informed consent, 40 patients undergoing elective surgery (≥1-hour) randomly received desflurane or sevoflurane. Patients swallowed 20mL of water without drooling or coughing, and then received sedation and PONV pre-medication. Anesthesia was induced using propofol and fentanyl and maintained with desflurane or sevoflurane through a laryngeal mask airway maintaining a bispectral index of 45-50 and 50-60 during the final 15minutes before surgery end. Cardiorespiratory variables and age-adjusted minimal alveolar concentration were recorded. The duration between anesthetic discontinuation and first appropriate response to command was measured; the laryngeal mask airway was removed. Two minutes after responding to command, patients were positioned semi-upright and attempted to swallow water. If successful swallowing was not achieved, the test was repeated every 4minutes after each failure until successful swallowing was achieved. Average anesthetic concentration and bispectral index was similar in patients receiving desflurane vs sevoflurane. Response times after discontinuation of anesthetics were similar. There were no differences in the recovery of swallowing ability between desflurane and sevoflurane groups. Weaning of sevoflurane during the final 15 minutes of surgery eliminates clinical advantages of the more rapid return of airway reflexes with desflurane.

Anesthetic Management Using Multiple Closed-loop Systems and Delayed Neurocognitive Recovery: A Randomized Controlled Trial.

Cognitive changes after anesthesia and surgery represent a significant public health concern. We tested the hypothesis that, in patients 60 yr or older scheduled for noncardiac surgery, automated management of anesthetic depth, cardiac blood flow, and protective lung ventilation using three independent controllers would outperform manual control of these variables. Additionally, as a result of the improved management, patients in the automated group would experience less postoperative neurocognitive impairment compared to patients having standard, manually adjusted anesthesia. In this single-center, patient-and-evaluator-blinded, two-arm, parallel, randomized controlled, superiority study, 90 patients having noncardiac surgery under general anesthesia were randomly assigned to one of two groups. In the control group, anesthesia management was performed manually while in the closed-loop group, the titration of anesthesia, analgesia, fluids, and ventilation was performed by three independent controllers. The primary outcome was a change in a cognition score (the 30-item Montreal Cognitive Assessment) from preoperative values to those measures 1 week postsurgery. Secondary outcomes included a battery of neurocognitive tests completed at both 1 week and 3 months postsurgery as well as 30-day postsurgical outcomes. Forty-three controls and 44 closed-loop patients were assessed for the primary outcome. There was a difference in the cognition score compared to baseline in the control group versus the closed-loop group 1 week postsurgery (-1 [-2 to 0] vs. 0 [-1 to 1]; difference 1 [95% CI, 0 to 3], P = 0.033). Patients in the closed-loop group spent less time during surgery with a Bispectral Index less than 40, had less end-tidal hypocapnia, and had a lower fluid balance compared to the control group. Automated anesthetic management using the combination of three controllers outperforms manual control and may have an impact on delayed neurocognitive recovery. However, given the study design, it is not possible to determine the relative contribution of each controller on the cognition score.

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

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