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Background: 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. Methods: 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. Results: 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. Conclusion: 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. [ABSTRACT FROM AUTHOR]

A recent study published in Acta Anesthesiologica Scandinavica compared the effects of methadone and morphine for postoperative pain management after bladder cancer surgery. The study found that a single dose of methadone did not result in significant opioid-sparing effects or pain reduction compared to morphine. While some patients reported higher satisfaction with methadone, the overall findings question the clinical benefits of methadone over morphine in this context. Further research is needed to determine if specific patient populations or types of surgery may benefit from methadone or if morphine remains a reliable choice for pain control after major surgeries. [Extracted from the article]

During a 2-week period, we have encountered five cases presenting with the combination of cerebral venous thrombosis (CVT), intracerebral hemorrhage and thrombocytopenia. A clinical hallmark was the rapid and severe progression of disease in spite of maximum treatment efforts, resulting in fatal outcome in for 4 out of 5 patients. All cases had received ChAdOx1 nCov-19 vaccine 1–2 weeks earlier and developed a characteristic syndrome thereafter. The rapid progressive clinical course and high fatality rate of CVT in combination with thrombocytopenia in such a cluster and in otherwise healthy adults is a recent phenomenon. Cerebral autopsy findings were those of venous hemorrhagic infarctions and thrombi in dural venous sinuses, including thrombus material apparently rich in thrombocytes, leukocytes and fibrin. Vessel walls were free of inflammation. Extra-cerebral manifestations included leech-like thrombi in large veins, fibrin clots in small venules and scattered hemorrhages on skin and membranes. CVT with thrombocytopenia after adenovirus vectored COVID-19 vaccination is a new clinical syndrome that needs to be recognized by clinicians, is challenging to treat and seems associated with a high mortality rate. [ABSTRACT FROM AUTHOR]

How and to what extent electrical brain activity reflects pharmacologically altered states and contents of consciousness, is not well understood. Therefore, we investigated whether measures of evoked and spontaneous electroencephalographic (EEG) signal diversity are altered by sub-anaesthetic levels of ketamine compared to normal wakefulness, and how these measures relate to subjective experience. High-density 62-channel EEG was used to record spontaneous brain activity and responses evoked by transcranial magnetic stimulation (TMS) in 10 healthy volunteers before and during administration of sub-anaesthetic doses of ketamine in an open-label within-subject design. Evoked signal diversity was assessed using the perturbational complexity index (PCI), calculated from EEG responses to TMS perturbations. Signal diversity of spontaneous EEG, with eyes open and eyes closed, was assessed by Lempel Ziv complexity (LZc), amplitude coalition entropy (ACE), and synchrony coalition entropy (SCE). Although no significant difference was found in TMS-evoked complexity (PCI) between the sub-anaesthetic ketamine condition and normal wakefulness, all measures of spontaneous EEG signal diversity (LZc, ACE, SCE) showed significantly increased values in the sub-anaesthetic ketamine condition. This increase in signal diversity correlated with subjective assessment of altered states of consciousness. Moreover, spontaneous signal diversity was significantly higher when participants had eyes open compared to eyes closed, both during normal wakefulness and during influence of sub-anaesthetic ketamine. The results suggest that PCI and spontaneous signal diversity may reflect distinct, complementary aspects of changes in brain properties related to altered states of consciousness: the brain's capacity for information integration, assessed by PCI, might be indicative of the brain's ability to sustain consciousness, while spontaneous complexity, as measured by EEG signal diversity, may be indicative of the complexity of conscious content. Thus, sub-anaesthetic ketamine may increase the complexity of the conscious content and the brain activity underlying it, while the level or general capacity for consciousness remains largely unaffected. [ABSTRACT FROM AUTHOR]

Background: Onvision is a new technology for needle tip detection and tracking in ultrasound-guided regional anesthesia. The system consists of a piezoelectric sensor close to the needle tip and an electronic console integrated in the ultrasound system. The needle tip is visualized by a green circle on the ultrasound screen. The aim of the study was to investigate the effect of the new needle tip tracking technology on in-plane infraclavicular plexus blocks.Methods: The study was a randomized, controlled, observer blinded cross-over trial in 26 healthy volunteers. Two specialists in anesthesiology performed an ultrasound-guided infraclavicular lateral sagittal brachial plexus block with and without needle tip tracking. Primary outcome was procedure time, measured from insertion of the needle until local anesthesia injection was completed. Secondary outcome measures included the number of hand movements and path lengths (assessed by hand motion analysis), block success rate, onset time and duration, discomfort experienced by the volunteers, and the anesthesiologists' confidence as to whether their block would be successful or not.Results: Mean (SD) procedure time was 183.0 (56.1) s with and 206.8 (56.2) s without needle tip tracking (p=0.16). There were no significant differences in any of the secondary outcomes. Two volunteers' experienced Horner syndrome after blocks without needle tip tracking. No other adverse events occurred during the study.Conclusion: Our study on needle tip tracking for infraclavicular blocks did not reveal any significant differences between active needle tip tracking and the control procedures, neither for primary outcome nor secondary outcome measurements.Trial Registration Number: NCT03631914. [ABSTRACT FROM AUTHOR]

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Background: The Onvision needle tip tracking (NTT) is a new technology consisting of a needle with an ultrasound sensor close to the needle tip and a console for computerised signal processing. The aim of the study was to evaluate NTT technology during ultrasound-guided simulated peripheral nerve block procedures in a porcine phantom model.Methods: Forty anaesthesiologists performed in-plane and out-of-plane simulated nerve blocks with and without NTT guidance. The primary outcome measure was procedure time. Secondary outcomes were hand movements and the path length travelled by the hands measured by motion analysis, precision of the needle tip related to the target structure, success rates and violations of the target structure, and the participants confidence whether their procedure would be successful or not.Results: Procedure time was reduced from 66.7 (SD = 47.5) seconds to 43.8 (SD = 29.2) seconds when NTT was used for out-of-plane procedures (P = 0.002). The number of hand movements of the probe hand was 13.9 (SD = 30.2) with NTT and 22.8 (SD = 30.0) without NTT (P = 0.019). No significant differences were registered during the performance of in-plane procedures. The participants confidence in a presumed block success was increased with both in-plane procedures (8.50 (SD = 1.18) with NTT vs 7.65 (SD = 1.96), P = 0.004) and out-of-plane procedures (8.50 (SD = 1.09) vs 7.10 (SD = 1.89), P = 0.0001).Conclusions: The new NTT technology significantly reduced the procedure time and the number of hand movements for ultrasound-guided out-of-plane PNB procedures. No significant differences were found for the in-plane procedures. [ABSTRACT FROM AUTHOR]

Temporary parent vessel clip occlusion in aneurysm surgery is not always practical or feasible. Adenosine-induced transient cardiac arrest may serve as an alternative. We retrospectively reviewed our clinical database between September 2011 and July 2014. All patients who underwent microsurgical clipping of intracranial aneurysms under adenosine-induced asystole were included. A total of 18 craniotomies were performed, and 18 aneurysms were clipped under adenosine-induced asystole (7 basilar arteries, 8 internal carotid arteries, 1 middle cerebral artery, and 1 anterior communicating artery) in 16 patients (10 females, 6 males). Nine cases were elective and seven after subarachnoid hemorrhage. Mean age was 54 years (range 39-70). The indications for adenosine use were proximal control in narrow surgical corridors in 13 cases and “aneurysm softening” in 4 cases. A single dose was used in 14 patients; 3 patients had multiple boluses. The median (range) total dose was 30 (18-135) mg. Adenosine induced a bradycardia with concomitant arterial hypotension in all patients, and the majority also had asystole for 5-15 sec. Transient cardiac arrhythmias were noted in one patient (AFib in need of electroconversion after two boluses). Nine clinical scenarios where adenosine-induced temporary cardiac arrest and deep hypotension was an effective adjunct to temporary clipping during microsurgical clipping of intracranial aneurysms were identified. [ABSTRACT FROM AUTHOR]

Objective: The objective of this study was to test whether properties of 1-s segments of spontaneous scalp EEG activity can be used to automatically distinguish the awake state from the anesthetized state in patients undergoing general propofol anesthesia. Methods: Twenty five channel EEG was recorded from 10 patients undergoing general intravenous propofol anesthesia with remifentanil during anterior cervical discectomy and fusion. From this, we extracted properties of the EEG by applying the Directed Transfer Function (DTF) directly to every 1-s segment of the raw EEG signal. The extracted properties were used to develop a data-driven classification algorithm to categorize patients as “anesthetized” or “awake” for every 1-s segment of raw EEG. Results: The properties of the EEG signal were significantly different in the awake and anesthetized states for at least 8 of the 25 channels (p < 0.05, Bonferroni corrected Wilcoxon rank-sum tests). Using these differences, our algorithms achieved classification accuracies of 95.9%. Conclusion: Properties of the DTF calculated from 1-s segments of raw EEG can be used to reliably classify whether the patients undergoing general anesthesia with propofol and remifentanil were awake or anesthetized. Significance: This method may be useful for developing automatic real-time monitors of anesthesia. [ABSTRACT FROM AUTHOR]

Background: The Shamrock technique is a new method for ultrasound-guided lumbar plexus blockade. Data on the optimal local anaesthetic dose are not available.Objective: The objective of this study is to estimate the effective dose of ropivacaine 0.5% for a Shamrock lumbar plexus block.Design: A prospective dose-finding study using Dixon's up-and-down sequential method.Setting: University Hospital Orthopaedic Anaesthesia Unit.Intervention: Shamrock lumbar plexus block performance and block assessment were scheduled preoperatively. Ropivacaine 0.5% was titrated with the Dixon and Massey up-and-down method using a stepwise change of 5 ml in each consecutive patient. Combined blocks of the femoral, the lateral femoral cutaneous and the obturator nerve were prerequisite for a successful lumbar plexus block.Patients: Thirty patients scheduled for lower limb orthopaedic surgery completed the study.Main Outcome Measures: The minimum effective anaesthetic volume of ropivacaine 0.5% (ED50) to achieve a successful Shamrock lumbar plexus block in 50% of the patients. Further analysis of the data was performed with a logistic regression model to calculate ED95 and to estimate the effective doses for a sensory lumbar plexus block not requiring a motor block of the femoral nerve.Results: The Dixon and Massay estimate of the ED50 was 20.4 [95% confidence interval (95% CI) 13.9 to 30.0] ml ropivacaine 0.5%. The logistic regression estimate of the ED95 was 36.0 (95% CI 19.7 to 52.2) ml ropivacaine 0.5%. For a sensory lumbar plexus block, the ED50 was 17.1 (95% CI 12.3 to 21.9) ml and the ED95 was 25.8 (95% CI 18.6 to 33.1) ml.Conclusion: A volume of 20.4 ml ropivacaine 0.5% provided a successful Shamrock lumbar plexus block in 50% of the patients. A volume of 36.0 ml would be successful in 95% of the patients.Trial Registration: ClinicalTrials.gov identifier NCT01956617. [ABSTRACT FROM AUTHOR]