Local wakefulness-like activity of layer 5 cortex under general anaesthesia.

Consciousness, defined as being aware of and responsive to one's surroundings, is characteristic of normal waking life and typically is lost during sleep and general anaesthesia. The traditional view of consciousness as a global brain state has evolved toward a more sophisticated interplay between global and local states, with the presence of local sleep in the awake brain and local wakefulness in the sleeping brain. However, this interplay is not clear for general anaesthesia, where loss of consciousness was recently suggested to be associated with a global state of brain-wide synchrony that selectively involves layer 5 cortical pyramidal neurons across sensory, motor and associative areas. According to this global view, local wakefulness of layer 5 cortex should be incompatible with deep anaesthesia, a hypothesis that deserves to be scrutinised with causal manipulations. Here, we show that unilateral chemogenetic activation of layer 5 pyramidal neurons in the sensorimotor cortex of isoflurane-anaesthetised mice induces a local state transition from slow-wave activity to tonic firing in the transfected hemisphere. This wakefulness-like activity dramatically disrupts layer 5 interhemispheric synchrony with mirror-image locations in the contralateral hemisphere, but does not reduce the level of unconsciousness under deep anaesthesia, nor in the transitions to/from anaesthesia. Global layer 5 synchrony may thus be a sufficient condition for anaesthesia-induced unconsciousness, but is not a necessary one, at least under isoflurane anaesthesia. Local wakefulness-like activity of layer 5 cortex can be induced and maintained under deep anaesthesia, encouraging further investigation into the local vs. global aspects of anaesthesia-induced unconsciousness. KEY POINTS: The neural correlates of consciousness have evolved from global brain states to a nuanced interplay between global and local states, evident in terms of local sleep in awake brains and local wakefulness in sleeping brains. The concept of local wakefulness remains unclear for general anaesthesia, where the loss of consciousness has been recently suggested to involve brain-wide synchrony of layer 5 cortical neurons. We found that local wakefulness-like activity of layer 5 cortical can be chemogenetically induced in anaesthetised mice without affecting the depth of anaesthesia or the transitions to and from unconsciousness. Global layer 5 synchrony may thus be a sufficient but not necessary feature for the unconsciousness induced by general anaesthesia. Local wakefulness-like activity of layer 5 neurons is compatible with general anaesthesia, thus promoting further investigation into the local vs. global aspects of anaesthesia-induced unconsciousness.

Laminar evoked responses in mouse somatosensory cortex suggest a special role for deep layers in cortical complexity.

It has been suggested that consciousness is closely related to the complexity of the brain. The perturbational complexity index (PCI) has been used in humans and rodents to distinguish conscious from unconscious states based on the global cortical responses (recorded by electroencephalography, EEG) to local cortical stimulation (CS). However, it is unclear how different cortical layers respond to CS and contribute to the resulting intra- and inter-areal cortical connectivity and PCI. A detailed investigation of the local dynamics is needed to understand the basis for PCI. We hypothesized that the complexity level of global cortical responses (PCI) correlates with layer-specific activity and connectivity. We tested this idea by measuring global cortical dynamics and layer-specific activity in the somatosensory cortex (S1) of mice, combining cortical electrical stimulation in deep motor cortex, global electrocorticography (ECoG) and local laminar recordings from layers 1-6 in S1, during wakefulness and general anaesthesia (sevoflurane). We found that the transition from wake to sevoflurane anaesthesia correlated with a drop in both the global and local PCI (PCIst ) values (complexity). This was accompanied by a local decrease in neural firing rate, spike-field coherence and long-range functional connectivity specific to deep layers (L5, L6). Our results suggest that deep cortical layers are mechanistically important for changes in PCI and thereby for changes in the state of consciousness.

Brain state-dependent responses of midbrain dopaminergic neurons to footshock under urethane anaesthesia.

For a long time, it has been assumed that dopaminergic (DA) neurons in both the ventral tegmental area (VTA) and the substantia nigra pars compacta (SNc) uniformly respond to rewarding and aversive stimuli by either increasing or decreasing their activity, respectively. This response was believed to signal information about the perceived stimuli's values. The identification of VTA&SNc DA neurons that are excited by both rewarding and aversive stimuli has led to the categorisation of VTA&SNc DA neurons into two subpopulations: one signalling the value and the other signalling the salience of the stimuli. It has been shown that the general state of the brain can modulate the electrical activity of VTA&SNc DA neurons, but it remains unknown whether this factor may also influence responses to aversive stimuli, such as a footshock (FS). To address this question, we have recorded the responses of VTA&SNc DA neurons to FSs across cortical activation and slow wave activity brain states in urethane-anaesthetised rats. Adding to the knowledge of aversion signalling by midbrain DA neurons, we report that significant proportion of VTA&SNc DA neurons can change their responses to an aversive stimulus in a brain state-dependent manner. The majority of these neurons decreased their activity in response to FS during cortical activation but switched to increasing it during slow wave activity. It can be hypothesised that this subpopulation of DA neurons may be involved in the 'dual signalling' of both the value and the salience of the stimuli, depending on the general state of the brain.

The arousal level of consciousness required for working memory performance: An anaesthesia study.

Regarding the stage of arousal level required for working memory to function properly, limited studies have been conducted on changes in working memory performance when the arousal level of consciousness decreases. This study aimed to experimentally clarify the stages of consciousness necessary for optimal working memory function. In this experiment, the sedation levels were changed step-by-step using anaesthesia, and the performance accuracy during the execution of working memory was assessed using a dual-task paradigm. Participants were required to categorize and remember words in a specific target category. Categorization performance was measured across four different sedative phases: before anaesthesia (baseline), and deep, moderate and light stages of sedation. Short-delay recognition tasks were performed under these four sedative stages, followed by long-delay recognition tasks after participants recovered from sedation. The results of the short-delay recognition task showed that the performance was lowest at the deep stage. The performance of the moderate stage was lower than the baseline. In the long-delay recognition task, the performance under moderate sedation was lower than that under baseline and light sedation. In addition, the performance under light sedation was lower than that under baseline. These results suggest that task performance becomes difficult under half sedation and that transferring information to long-term memory is difficult even under one-quarter sedation.

An exploratory research report on brain mineralization in postoperative delirium and cognitive decline.

Delirium is a severe postoperative complication associated with poor overall and especially neurocognitive prognosis. Altered brain mineralization is found in neurodegenerative disorders but has not been studied in postoperative delirium and postoperative cognitive decline. We hypothesized that mineralization-related hypointensity in susceptibility-weighted magnetic resonance imaging (SWI) is associated with postoperative delirium and cognitive decline. In an exploratory, hypothesis-generating study, we analysed a subsample of cognitively healthy patients ≥65 years who underwent SWI before (N = 65) and 3 months after surgery (N = 33). We measured relative SWI intensities in the basal ganglia, hippocampus and posterior basal forebrain cholinergic system (pBFCS). A post hoc analysis of two pBFCS subregions (Ch4, Ch4p) was conducted. Patients were screened for delirium until the seventh postoperative day. Cognitive testing was performed before and 3 months after surgery. Fourteen patients developed delirium. After adjustment for age, sex, preoperative cognition and region volume, only pBFCS hypointensity was associated with delirium (regression coefficient [90% CI]: B = -15.3 [-31.6; -0.8]). After adjustments for surgery duration, age, sex and region volume, perioperative change in relative SWI intensities of the pBFCS was associated with cognitive decline 3 months after surgery at a trend level (B = 6.8 [-0.9; 14.1]), which was probably driven by a stronger association in subregion Ch4p (B = 9.3 [2.3; 16.2]). Brain mineralization, particularly in the cerebral cholinergic system, could be a pathomechanism in postoperative delirium and cognitive decline. Evidence from our studies is limited because of the small sample and a SWI dataset unfit for iron quantification, and the analyses presented here should be considered exploratory.

Effect of isoflurane anaesthetic time on ocular a-scan ultrasonography measures and their relationship to age and OCT measures in the Guinea pig.

A-scan ultrasonography enables precise measurement of internal ocular structures. Historically, its use has underpinned fundamental studies of eye development and aberrant eye growth in animal models of myopia; however, the procedure typically requires anaesthesia. Since anaesthesia affects intra-ocular pressure (IOP), we investigated changes in internal ocular structures with isoflurane exposure and compared measurements with those taken in awake animals using optical coherence tomography (OCT). Continuous A-scan ultrasonography was undertaken in tri-coloured guinea pigs aged 21 (n = 5), 90 (n = 5) or 160 (n = 5) days while anaesthetised (up to 36 min) with isoflurane (5% in 1.5L/min O2). Peaks were selected from ultrasound traces corresponding to the boundaries of the cornea, crystalline lens, retina, choroid and sclera. OCT scans (Zeiss Cirrus Photo 800) of the posterior eye layers were taken in 28-day-old animals (n = 19) and compared with ultrasound traces, with choroid and scleral thickness adjusted for the duration of anaesthesia based on the changes modelled in 21-day-old animals. Ultrasound traces recorded sequentially in left and right eyes in 14-day-old animals (n = 30) were compared, with each adjusted for anaesthesia duration. The thickness of the cornea was measured in enucleated eyes (n = 5) using OCT following the application of ultrasound gel (up to 20 min). Retinal thickness was the only ultrasound internal measure unaffected by anaesthesia. All other internal distances rapidly changed and were well fitted by exponential functions (either rise-to-max or decay). After 10 and 20 min of anaesthesia, the thickness of the cornea, crystalline lens and sclera increased by 17.1% and 23.3%, 0.4% and 0.6%, and 5.2% and 6.5% respectively, whilst the anterior chamber, vitreous chamber and choroid decreased by 4.4% and 6.1%, 0.7% and 1.1%, and 10.7% and 11.8% respectively. In enucleated eyes, prolonged contact of the cornea with ultrasound gel resulted in an increase in thickness of 9.3% after 10 min, accounting for approximately half of the expansion observed in live animals. At the back of the eye, ultrasound measurements of the thickness of the retina, choroid and sclera were highly correlated with those from posterior segment OCT images (R2 = 0.92, p = 1.2 × 10-13, R2 = 0.55, p = 4.0 × 10-4, R2 = 0.72, p = 5.0 × 10-6 respectively). Furthermore, ultrasound measures for all ocular components were highly correlated in left and right eyes measured sequentially, when each was adjusted for anaesthetic depth. This study shows that the depth of ocular components can change dramatically with anaesthesia. Researchers should therefore be wary of these concomitant effects and should employ adjustments to better render 'true' values.

Non-surgical correction of knee flexion deformity in persons with haemophilia: A staged multidisciplinary approach.

INTRODUCTION: Flexion deformity of the knee is a common complication following recurrent haemarthrosis in persons with haemophilia (PWH) on episodic factor replacement therapy, restricting independent mobility. There is limited literature on the comprehensive management of this condition. This report provides the outcome of a staged multidisciplinary approach for the correction of knee flexion deformity (KFD) even in limited resource settings. PATIENTS AND METHODS: The data of 49 consecutive PWH who were treated for KFD were analysed. The approach included graded physical therapy (PT), followed by serial casting and/or mobilisation under anaesthesia (MUA). MUA was done in carefully selected knees. Surgical correction was opted when non-surgical methods failed. RESULTS: Of the 49 patients (55 knees), with a median KFD of 40 degrees (range: 10-90), 26/55 (47%) were corrected by graded PT. With serial casting, 9/19 (47%) knees had their KFD corrected. MUA was done for 11 knees of which five achieved correction (45%). Surgical correction was required for only seven knees (12.7%). Following this approach, KFD improved from 40 degrees (range: 10-90) to 15 degrees (range: 0-40), with only minor loss of flexion from 105 (range: 60-155) to 90 degrees (range: 30-150). Out of 55 KFD, 46 (83.6%) KFD were corrected; non-surgical, 39 (70.9%) and surgery, seven (12.7%). The remaining patients (nine KFD; 16.4%) were able to achieve their functional goal despite not meeting the correction criteria. CONCLUSION: This study shows that in PWH, functionally significant KFD correction can be achieved in about 71%, through non-surgical methods, even without prophylactic factor replacement.

Dental management of people with complex or rare inherited bleeding disorders.

Advances in haematological therapies for people with complex or rare inherited bleeding disorders (IBD) have resulted in them living longer, retaining their natural teeth with greater expectations of function and aesthetics. Dental management strategies need to evolve to meet these challenges. Utilising low level laser diode therapy to reduce pre-operative inflammation to reduce the intraoperative and postoperative burden on haemostasis is described in a case series of 12 patients. For these individuals who previously required further medical management to support haemostasis or experienced such prolonged haemorrhage sufficient to warrant hospital admission, haemostasis was achieved in the dental surgery such that they were able to return home with no further medical intervention or overnight stays. Global inequities in accessing novel treatments for complex or rare IBD necessitates a comprehensive understanding of the local haemostatic agents available to dentists and the most commonly used agents and techniques are described including the use of single tooth anaesthesia (STA). STA is a computerised delivery mechanism that allows routine dental procedures that would previously have required block injections needing factor replacement therapy to be undertaken safely and effectively with no additional haemostatic intervention. The challenges of inhibitors in oral surgery are explained and discussed although more research and evidence is required to establish new treatment protocols. The importance of establishing good dental health in the quality of life of people with complex or rare IBD is highlighted with respect to the dental specific impact that more novel therapies may have on people with IBD.

Cardiovascular physiology of decapod crustaceans: from scientific inquiry to practical applications.

Until recently, the decapod crustacean heart was regarded as a simple, single ventricle, contraction of which forces haemolymph out into seven arteries. Differential tissue perfusion is achieved by contraction and relaxation of valves at the base of each artery. In this Review, we discuss recent work that has shown that the heart is bifurcated by muscular sheets that may effectively divide the single ventricle into 'chambers'. Preliminary research shows that these chambers may contract differentially; whether this enables selective tissue perfusion remains to be seen. Crustaceans are unusual in that they can stop their heart for extended periods. These periods of cardiac arrest can become remarkably rhythmic, accounting for a significant portion of the cardiac repertoire. As we discuss in this Review, in crustaceans, changes in heart rate have been used extensively as a measurement of stress and metabolism. We suggest that the periods of cardiac pausing should also be quantified in this context. In the past three decades, an exponential increase in crustacean aquaculture has occurred and heart rate (and changes thereof) is being used to understand the stress responses of farmed crustaceans, as well as providing an indicator of disease progression. Furthermore, as summarized in this Review, heart rate is now being used as an effective indicator of humane methods to anaesthetize, stun or euthanize crustaceans destined for the table or for use in scientific research. We believe that incorporation of new biomedical technology and new animal welfare policies will guide future research directions in this field.

Non-infectious adverse events of transperineal prostate biopsies performed under local anaesthesia.

OBJECTIVE: To report non-infectious adverse events associated with transperineal prostate biopsy (TPBx) performed under local anaesthesia (LA) in an outpatient setting. PATIENTS AND METHODS: This study reports secondary outcomes from the Norwegian arm of the prospective NORAPP study (ClinicalTrials.gov identifier NCT04146142) and included all patients referred for prostate biopsy from November 2019 to February 2021. Transperineal magnetic resonance imaging-transrectal ultrasonography fusion TPBx were taken using 40 mL 1% lidocaine with 4 mL of 8.4% sodium bicarbonate placed in the perineal skin, under the prostatic apex, in the m. levator ani bilaterally, and along the path of the needle. Follow-up using patient-reported questionnaires was done immediately after TPBx, and after 2 weeks and 2 months. Pain was reported using a visual analogue scale (VAS) during placement of the LA, and during and after TPBx. Haematuria and acute urinary retention (AUR) rates were recorded. RESULTS: We included 402 patients, and the response rate was 99.8% (401/402). The median (interquartile range [IQR]) age was 69 (63-74) years, the prostate volume was 40 (27-58) mL, the prostate-specific antigen level was 7.0 (4.5-11) ng/mL, and the number of biopsy cores taken was 8 (6-10). The median (IQR) VAS pain score was 1 (1-2) during placement of LA, 1 (0-2) during TPBx, and 0 (0-0) after TPBx. Haematuria and AUR rates were 64% (95% confidence interval [CI] 60-69%) and 0.5% (95% CI 0.1-1.8%), respectively. No patients were hospitalised or required after the TPBx surgical intervention. CONCLUSION: Transperineal prostate biopsies can be performed under LA with limited discomfort to the patient and few post-TPBx adverse events.

A retrospective analysis of perioperative medications for opioid-use disorder and tapering additional postsurgical opioids via a transitional pain service.

AIMS: To investigate perioperative opioid requirements in patients on methadone or buprenorphine as medication for opioid-use disorder (MOUD) who attended a transitional pain clinic (Personalized Pain Program, PPP). METHODS: This retrospective cohort study assessed adults on MOUD with surgery and attendance at the Johns Hopkins PPP between 2017 and 2022. Daily non-MOUD opioid use over 6 time-points was evaluated with regression models controlling for days since surgery. The time to complete non-MOUD opioid taper was analysed by accelerated failure time and Kaplan-Meier models. RESULTS: Fifty patients (28 on methadone, 22 on buprenorphine) were included with a median age of 44.3 years, 54% male, 62% Caucasian and 54% unemployed. MOUD inpatient administration occurred in 92.8% of patients on preoperative methadone but only in 36.3% of patients on preoperative buprenorphine. Non-MOUD opioid use decreased over time postoperatively (ß = -0.54, P < .001) with a median decrease of 90 mg morphine equivalents (MME) between the first and last PPP visit, resulting in 46% tapered off by PPP completion. Older age and duration in PPP were associated with lower MME, while mental health conditions, longer hospital stays and higher discharge opioid prescriptions were associated with higher MME. The average time to non-MOUD opioid taper was 1.79× longer in patients on buprenorphine (P = .026), 2.75× in males (P = .023), 4.66× with mental health conditions (P < .001), 2.37× with chronic pain (P = .031) and 3.51× if on preoperative non-MOUD opioids; however, higher initial MOUD level decreased time to taper (P = .001). CONCLUSIONS: Postoperative opioid tapering utilizing a transitional pain service is possible in patients on MOUD.

Psychedelic research, assisted therapy and the role of the anaesthetist: A review and insights for experimental and clinical practices.

Recent years have witnessed an unprecedented increase in the search for the use of psychedelics in improving physical and mental health. Anaesthesia has evolved since very early times, born from the need to eliminate pain and reduce suffering and there are reports of the use of anaesthetics to achieve mystical states since the nineteenth century. Nowadays, the renaissance of psychedelics in anaesthesia has been inspired by their potential in the treatment of chronic pain syndromes, palliative care and in the emergency department and pre-hospital care with the administration of psychedelics in cases of ischaemia, given their potential in neuroprotection. Although there are already some published protocols for the administration of psychedelics in patients with mental illness, little has been addressed concerning non-mental medical applications. In this sense, in patients with multiple comorbidities, functional limitations and polymedicated, the anaesthetist may play a fundamental role, not only in clinical practice, but also in translational research. This article focuses on the description of psychedelics, with a particular focus on dimethyltryptamine (DMT) and ayahuasca pharmacology, effects, safety and toxicity. A detailed description of the role of the anaesthetist in clinical and experimental research is provided, from participant's screening to preparation and dosing session, expected adverse effects and how to manage them, based on the protocol and standard procedures of a current study with neuroimaging during the psychedelic experience. Specific considerations regarding the management of psychedelic toxicity are also provided as well as future directions for safe psychedelic use in clinical practice.

General anaesthesia compared to conscious sedation for first-time atrial fibrillation catheter ablation-a Danish nationwide cohort study.

AIMS: Catheter ablation (CA) is a well-established treatment option for atrial fibrillation (AF), where sedation and analgesia are pivotal for patient comfort and lesion formation. The impact of anaesthesia type on AF recurrence rates remains uncertain. This study aimed to examine AF recurrence rates depending on conscious sedation (CS) vs. general anaesthesia (GA) during CA. METHODS AND RESULTS: Utilizing nationwide data from the Danish healthcare registries, we conducted this cohort study involving adults (≥18 years) undergoing first-time CA for AF between 2010 and 2018. Patients were categorized by anaesthesia type (CS or GA), with the primary endpoint being AF recurrence, defined by a composite endpoint of either antiarrhythmic drug (AAD) prescriptions, AF-related hospital admissions, electrical cardioversions, or AF re-ablation. The impact of anaesthesia type was evaluated using multivariable Cox proportional hazards analysis. The study cohort comprised 7957 (6421 CS and 1536 GA) patients. Persistent AF, hypertension, and heart failure, as well as use of AAD, were more prevalent in the GA group. Cumulative incidences of recurrent AF were higher in the CS group at 1 (46% vs. 37%) and at 5 (68% vs. 63%) years. Multivariate analysis revealed CS as significantly associated with increased risk of AF recurrence at 5-year follow-up [hazard ratio 1.26 (95% confidence interval 1.15-1.38)], consistent across paroxysmal and persistent AF subtypes. CONCLUSION: This nationwide cohort study suggests a higher risk of AF recurrence with CS during CA compared to GA. These results advocate for considering GA as the preferred anaesthesia type for improved CA outcomes.

Continuous stellate ganglion block for ventricular arrhythmias: case series, systematic review, and differences from thoracic epidural anaesthesia.

AIMS: Percutaneous stellate ganglion block (PSGB) through single-bolus injection and thoracic epidural anaesthesia (TEA) have been proposed for the acute management of refractory ventricular arrhythmias (VAs). However, data on continuous PSGB (C-PSGB) are scant. The aim of this study is to report our dual-centre experience with C-PSGB and to perform a systematic review on C-PSGB and TEA. METHODS AND RESULTS: Consecutive patients receiving C-PSGB at two centres were enrolled. The systematic literature review follows the latest Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. Our case series (26 patients, 88% male, 60 ± 16 years, all with advanced structural heart disease, left ventricular ejection fraction 23 ± 11%, 32 C-PSGBs performed, with a median duration of 3 days) shows that C-PSGB is feasible and safe and leads to complete VAs suppression in 59% and to overall clinical benefit in 94% of cases. Overall, 61 patients received 68 C-PSGBs and 22 TEA, with complete VA suppression in 63% of C-PSGBs (61% of patients). Most TEA procedures (55%) were performed on intubated patients, as opposed to 28% of C-PSGBs (P = 0.02); 63% of cases were on full anticoagulation at C-PSGB, none at TEA (P < 0.001). Ropivacaine and lidocaine were the most used drugs for C-PSGB, and the available data support a starting dose of 12 and 100 mg/h, respectively. No major complications occurred, yet TEA discontinuation rate due to side effects was higher than C-PSGB (18 vs. 1%, P = 0.01). CONCLUSION: Continuous PSGB seems feasible, safe, and effective for the acute management of refractory VAs. The antiarrhythmic effect may be accomplished with less concerns for concomitant anticoagulation compared with TEA and with a lower side-effect related discontinuation rate.

Cardiac implantable electronic devices in pregnancy: A position statement.

The aim of this document is to provide guidance for the management of women and birthing people with a permanent pacemaker (PPM) or implantable cardioverter defibrillator (ICD). Cardiac devices are becoming more common in obstetric practice and a reference document for contemporary evidence-based practice is required. Where evidence is limited, expert consensus has established recommendations. The purpose is to improve safety and reduce the risk of adverse events relating to implanted cardiac devices during pregnancy, birth and the postnatal period.

Analgesic effect of local anaesthetic in haemorrhoid banding: systematic review and meta-analysis.

PURPOSE: Rubber band ligation of haemorrhoids can be,painful and there is no consensus regarding the optimal analgesic strategy. This study aims to determine whether there is a difference in post-procedural pain in adults undergoing haemorrhoid banding who have received local anaesthetic, a pudendal nerve block or no regional or local analgesia. METHODS: MEDLINE, Embase, Google Scholar and clinical trial registries were searched for randomised trials of local anaesthetic or pudendal nerve block use in banding. Primary outcomes were patient-reported pain scores. The quality of the evidence was assessed using the GRADE approach. RESULTS: Seven studies were included in the final review. No articles were identified that studied pudendal nerve blocks. The difference in numerical pain scores between treatment groups favoured the local anaesthetic group at all timepoints. The mean difference in scores on a 10-point scale was at 1 h,-1.43 (95% CI-2.30 to-0.56, p < 0.01, n = 342 (175 in treatment group)); 6 h,-0.52 (95% CI-1.04 to 0.01, p = 0.05, n = 250 (130 in treatment group)); and 24 h,-0.31 (95% CI-0.82 to 0.19, p = 0.86, n = 247 (127 in treatment group)). Of reported safety outcomes, vasovagal symptoms proceeded to meta-analysis, with a risk ratio of 1.01 (95% CI 0.64-1.60). The quality of the evidence was rated down to 'low' due to inconsistency and imprecision. CONCLUSION: This review supports the use of LA for reducing early post-procedural pain following haemorrhoid banding. The evidence was limited by small sample sizes and substantial heterogeneity across studies. REGISTRATION: PROSPERO (ID CRD42022322234).

Two-stage laparoscopic transversus abdominis plane block as an equivalent alternative to thoracic epidural anaesthesia in bowel resection-an explorative cohort study.

PURPOSE: We evaluated the effect of the two-stage laparoscopic transversus abdominis plane block (TS-L-TAPB) in comparison to thoracic epidural anaesthesia (TEA) and a one-stage L-TAPB (OS-L-TAPB) in patients who underwent elective laparoscopic bowel resection. METHODS: We compared a TS-L-TAPB (266 mg bupivacaine), which was performed bilaterally at the beginning and end of surgery, with two retrospective cohorts. These were patients who had undergone a TEA (ropivacaine/sufentanil) or an OS-L-TAPB (200 mg ropivacaine) at the beginning of surgery. Oral and i.v. opiate requirements were documented over the first 3 postoperative days (POD). RESULTS: Patients were divided into three groups TEA (n = 23), OS-L-TAPB (n = 75), and TS-L-TAPB (n = 49). By the evening of the third POD, patients with a TEA had a higher cumulative opiate requirement with a median of 45.625 mg [0; 202.5] than patients in the OS-L-TAPB group at 10 mg [0; 245.625] and the TS-L-TAPB group at 5.625 mg [0; 215.625] (p = 0.1438). One hour after arrival in the recovery room, significantly more patients in the TEA group (100%) did not need oral and i.v. opioids than in the TS-L-TAPB (78%) and OS-L-TAPB groups (68%) (p = 0.0067).This was without clinical relevance however as the median in all groups was 0 mg. On the third POD, patients in the TEA group had a significantly higher median oral and i.v. opioid dose at 40 mg [0; 80] than the TS-L-TAPB and OS-L-TAPB groups, both at 0 mg [0; 80] (p = 0.0009). CONCLUSION: The TS-L-TAP showed statistically significant and clinically meaningful benefits over TEA and OS-L-TAP in reducing postoperative opiate requirements.

Propofol Reversibly Attenuates Short-Range Microstate Ordering and 20 Hz Microstate Oscillations.

Microstate sequences summarize the changing voltage patterns measured by electroencephalography, using a clustering approach to reduce the high dimensionality of the underlying data. A common approach is to restrict the pattern matching step to local maxima of the global field power (GFP) and to interpolate the microstate fit in between. In this study, we investigate how the anesthetic propofol affects microstate sequence periodicity and predictability, and how these metrics are changed by interpolation. We performed two frequency analyses on microstate sequences, one based on time-lagged mutual information, the other based on Fourier transform methodology, and quantified the effects of interpolation. Resting-state microstate sequences had a 20 Hz frequency peak related to dominant 10 Hz (alpha) rhythms, and the Fourier approach demonstrated that all five microstate classes followed this frequency. The 20 Hz periodicity was reversibly attenuated under moderate propofol sedation, as shown by mutual information and Fourier analysis. Characteristic microstate frequencies could only be observed in non-interpolated microstate sequences and were masked by smoothing effects of interpolation. Information-theoretic analysis revealed faster microstate dynamics and larger entropy rates under propofol, whereas Shannon entropy did not change significantly. In moderate sedation, active information storage decreased for non-interpolated sequences. Signatures of non-equilibrium dynamics were observed in non-interpolated sequences, but no changes were observed between sedation levels. All changes occurred while subjects were able to perform an auditory perception task. In summary, we show that low dose propofol reversibly increases the randomness of microstate sequences and attenuates microstate oscillations without correlation to cognitive task performance. Microstate dynamics between GFP peaks reflect physiological processes that are not accessible in interpolated sequences.

Cohort profile: the China surgery and anesthesia cohort (CSAC).

The China Surgery and Anaesthesia Cohort (CSAC) study was launched in July 2020 and is an ongoing prospective cohort study recruiting patients aged 40-65 years who underwent elective surgeries with general anaesthesia across four medical centres in China. The general objective of the CSAC study is to improve our understanding of the complex interaction between environmental and genetic components as well as to determine their effects on a wide range of interested surgery/anaesthesia-related outcomes. To achieve this goal, we collected enriched phenotypic data, e.g., sociodemographic characteristics, lifestyle factors, perioperative neuropsychological changes, anaesthesia- and surgery-related complications, and medical conditions, at recruitment, as well as through both active (at 1, 3, 7 days and 1, 3, 6, 12 months after surgery) and passive (for more than 1 year after surgery) follow-up assessments. We also obtained omics data from blood samples. In addition, COVID-19-related information was collected from all participants since January 2023, immediately after COVID-19 restrictions were eased in China. As of July 18, 2023, 12,766 participants (mean age = 52.40 years, 57.93% were female) completed baseline data collection (response rate = 94.68%), among which approximately 70% donated blood and hair samples. The follow-up rates within 12 months after surgery were > 92%. Our initial analyses have demonstrated the incidence of and risk factors for chronic postsurgical pain (CPSP) and postoperative cognitive dysfunction (POCD) among middle-aged Chinese individuals, which may prompt further mechanistic exploration and facilitate the development of effective interventions for preventing those conditions. Additional studies, such as genome-wide association analyses for identifying the genetic determinants of CPSP and POCD, are ongoing, and their findings will be released in the future.

Effects of inhalation versus total intravenous anaesthesia on long-term mortality in older patients after noncardiac surgery: a retrospective observational study.

BACKGROUND: Whether the anaesthetic agent used influences postoperative mortality in older patients remains unclear. We evaluated the effect of total intravenous anaesthesia (TIVA) vs inhalation anaesthesia on long-term mortality in older patients after noncardiac surgery. METHODS: We retrospectively analysed 45,879 patients aged ≥60 yr who underwent noncardiac surgery under general anaesthesia (for ≥2 h) between January 2011 and June 2019. They were divided into two groups according to the type of maintenance anaesthetic. The primary outcome was all-cause mortality within 1 yr after surgery. Secondary outcomes included postoperative complications (postoperative pulmonary complications, perioperative adverse cardiovascular events, and acute kidney injury), and 3-yr and 5-yr mortality after surgery. The stabilised inverse probability of treatment weighting method was used to adjust for potential confounders. RESULTS: Among 45,879 patients, 7273 (15.9%) patients received TIVA and 38,606 (84.1%) patients received inhalation anaesthesia. After adjustment with inverse probability of treatment weighting, there was no association between the type of anaesthetic agent and 1-yr mortality (hazard ratio=0.95; 95% confidence interval [CI] 0.84-1.08). Results for 3-yr and 5-yr mortality were similar. However, inhalation anaesthesia was associated with increased risk of postoperative complications (odds ratio [OR]=1.30; 95% CI 1.22-1.37 for postoperative pulmonary complications, OR=1.34; 95% CI 1.22-1.48 for perioperative adverse cardiovascular events, and OR=2.19; 95% CI 1.88-2.57 for acute kidney injury). In the subgroup analysis, the choice of anaesthetic agent showed differential effects on 1-yr mortality for female patients and emergency surgery. CONCLUSION: The choice of anaesthetic agent during the intraoperative period was not associated with 1-yr mortality in older patients undergoing noncardiac surgery. CLINICAL TRIAL REGISTRATION: Clinical Research Information Service of the Republic of Korea (KCT 0006363).