Effects of general anesthesia on behavioral circadian rhythms and clock-gene expression in the suprachiasmatic nucleus in rats

A chronopharmacological comparison of ciprofol and propofol: focus on sedation and side effects

Propofol is a commonly used intravenous anesthetic in clinical practice, while ciprofol, a propofol derivative, also targets GABAA receptors with enhanced anesthetic potency. Regarding chronopharmacology, it remains unclear whether the new drug ciprofol has improved anesthetic effect and less side effects compared with propofol. First, we assessed the critical anesthetic dosage (Dca) of ciprofol and propofol exhibited diurnal rhythmicity. At the highest Dca, the loss of righting reflex duration was significantly longer for ciprofol than that for propofol at both Zeitgeber Time (ZT) 4 and ZT16. The β3 subunits of the GABAA receptor, which are involved in mediating anesthetic effects, and the metabolizing enzyme UGT1A9 for propofol demonstrated rhythmic expression. Moreover, molecular dynamics simulation indicated a higher binding affinity of R-ciprofol to GABRB3 compared with propofol. Animal behavior experiments indicated that ciprofol was associated with no incidence of side effects at any time of day, while propofol exhibited circadian-related adverse effects. Notably, ciprofol infrequently disrupted the rhythmicity of clock gene expression compared to propofol. From a chronopharmacological perspective, ciprofol offers improved sedation and fewer side effects compared to propofol, suggesting its higher potential for clinical application.

Dexmedetomidine accelerates photoentrainment and affects sleep structure through the activation of SCNVIP neurons

Dexmedetomidine (DexM), a highly selective α2-adrenoceptor agonist, significantly reduces postoperative adverse effects, including sleep and circadian rhythm disruptions. Vasoactive intestinal peptide neurons in the suprachiasmatic nucleus (SCNVIP) regulate the synchronization of circadian rhythms with the external environment in mammals. We investigate the effects of DexM on sleep and circadian rhythms, as well as the underlying mechanisms. Using electrophysiological and chemogenetic methods, along with locomotor activity and electroencephalogram/electromyogram recordings, we found that DexM accelerates the rate of re-entrainment following an 8-hour phase advance in the 12-hour light:12-hour dark cycle, increases the amount of non-rapid eye movement sleep, and decreases the mean duration of rapid eye movement sleep. Chemogenetic inhibition of SCNVIP neurons hinders the acceleration of re-entrainment and the changes in the sleep-wakefulness cycle induced by DexM. Electrophysiological results show that DexM increases the firing rate and the frequency of spontaneous glutamatergic postsynaptic currents while decreasing the frequency of spontaneous GABAergic PSCs in SCNVIP neurons through the α2-adrenergic receptor. Additionally, DexM reduces the frequency of miniature GABAergic PSCs in SCNVIP neurons. In conclusion, these findings suggest that DexM promotes sleep and maintains the coordination of circadian rhythms with the external environment by activating SCNVIP neurons through the α2-adrenoceptor.

The impact of diurnal variations on emergence delirium following general anesthesia and surgery in children

Background

Emergence delirium (ED) is a widely recognized issue that prolongs mechanical ventilation and post-anesthesia care unit (PACU) resuscitation time, consequently increasing hospital costs and mortality. Postoperative disturbance in circadian rhythms, commonly leading to sleep disorders, has been identified as a significant risk factor for ED. However, the influence of surgery timing (morning vs. afternoon) on the incidence of ED in pediatric patients undergoing general anesthesia remains unknown.

Methods

Patients aged 2-6 years who were operated on under general anesthesia with a bispectral index value between 50 and 60 were categorized based on anesthesia start time into either the morning surgery group (Group M, 8:00-12:00) or the afternoon surgery group (Group A, 13:00-17:00). The primary outcome was the post-extubation incidence of ED assessed by the Cornell Assessment of Pediatric Delirium (CAPD) score. Secondary outcomes included extubation time, duration of PACU stay, and adverse postoperative events and complications.

Results

We recruited a total of 560 patients, 280 in group M and 280 in group A. Compared to Group M, Group A exhibited a significantly higher incidence of ED (p < 0.001), elevated CAPD scores (p < 0.001), and prolonged PACU stays (p < 0.001). Notably, there was no significant difference in extubation time and anesthesia-related adverse events or other postoperative complications between the groups.

Conclusion

Our study highlights that the time of surgery significantly affects the incidence of ED, CAPD scores, and PACU stay duration in children. Further validation of these findings may guide future strategies to reduce ED.

Study on the preventive effect of dexmedetomidine on anesthetic associated sleep disturbance in young to middle-aged female patients undergoing hysteroscopy: a study protocol for a crossover randomized controlled trial

BACKGROUND

Postoperative sleep disturbance has a potentially detrimental effect on postoperative recovery. Perioperative patients are affected by several factors. General anesthesia induces a non-physiological state that does not resemble natural sleep. Exposure to propofol/sevoflurane can lead to desynchronization of the circadian rhythm, which may result in postoperative sleep disturbance characterized by mid-cycle advancement of sleep and daytime sleepiness. Dexmedetomidine is a highly selective α2-adrenoceptor agonist with a unique sedative effect that facilitates the transition from sleep to wakefulness. Basic research has shown that dexmedetomidine induces deep sedation, similar to physical sleep, and helps maintain forebrain connectivity, which is likely to reduce delirium after surgery. The aim of this study is to evaluate the influence of exposure to the mono-anesthetic propofol on the development of postoperative sleep disturbance in young and middle-aged female patients undergoing hysteroscopy and whether prophylactic administration of dexmedetomidine influences reducing postoperative sleep disturbance.

METHODS

This prospective randomized controlled trial (RCT) will include 150 patients undergoing hysteroscopy at the First Affiliated Hospital of Xiamen University. Participants will be randomly assigned to three groups in a 1:1:1 ratio. The dexmedetomidine group will have two subgroups and will receive a nasal spray of 0.2 µg/kg or 0.5 µg/kg 25 min before surgery, while the control group will receive a saline nasal spray. Three groups will undergo hysteroscopy with propofol-based TIVA according to the same scheme. Sleep quality will be measured using a wearable device and double-blind sleep assessments will be performed before surgery and 1, 3, and 7 days after surgery. SPSS 2.0 is used for statistical analysis. A χ2 test is used to compare groups, and t-test is used to determine statistical the significance of continuous variables.

DISCUSSION

The purpose of this study is to investigate the incidence of propofol-associated sleep disorders and to test a combination of dexmedetomidine anesthesia regimen for the prevention of postoperative sleep disorders. This study will help to improve patients' postoperative satisfaction and provide a new strategy for comfortable perioperative medical treatment.

TRIAL REGISTRATION

ClinicalTrials.gov NCT06281561. Registered on February 24, 2024.

The timing of the mouse hind paw incision does not influence postsurgical pain

Chronobiological approaches have emerged as tools to study pain and inflammation. Although time-of-day effects on the expression of pain after injury have been studied, it remains unaddressed whether the timing of the injury itself can alter subsequent pain behaviors. The aim of this study was to assess postsurgical pain behaviors in a mouse hind paw incision assay in a circadian-dependent manner. Incisions were made at one of four equally spaced time points over a 24-hour period, with evoked and spontaneous pain behaviors measured using the von Frey mechanical sensitivity test, Hargreaves' radiant heat paw-withdrawal test, and the Mouse Grimace Scale. Algesiometric testing was performed in C57BL/6 mice prior to and at multiple time points after incision injury, at the same time of day, until pain resolution. No statistically significant differences were observed between groups. This study adds to the literature on circadian rhythms and their influence on pain in the pursuit of more biologically informed pre- and postoperative care.

Postoperative Pain Following Eye Enucleation: A Prospective Observational Study

Background and Objectives: Enucleation of an eye is the most invasive procedure in ophthalmologic surgery. It can be the result of various diseases (malignant/chronic/trauma/infection) and is nevertheless relatively rare, but leads to the loss of a strongly innervated neuronal organ. This study systematically evaluates postoperative pain levels following enucleation of the eye globe. Materials and Methods: This prospective single-center study enrolled twenty-four patients undergoing enucleation of the eye globe. Perioperatively all patients completed (preoperative day, day of surgery, 1st, 2nd, and 3rd day following surgery) standardized questionnaires concerning their pain experience and treatment-related side-effects (internal protocol, QUIPS, painDETECT®). Patients received usual pain therapy in an unstandardized individual manner. Results: Preoperatively, mean average pain intensity of all included patients was 3.29 ± 2.46 (range, 0-8), 3.29 ± 3.24 (range, 0-8) on the day of surgery, 4.67 ± 1.90 (range, 2-10) on day 1, 3.25 ± 1.39 (range, 1-6) on day 2, and 2.71 ± 1.30 (range, 1-6) on day 3 after surgery. Mean maximum pain intensity was 4.71 ± 3.28 (range, 0-10) preoperatively, 4.04 ± 3.78 (range, 0-10) on the day of surgery, 5.75 ± 2.01 (range, 2-10) on day 1, 4.25 ± 1.89 (range, 2-10) on day 2, and 3.88 ± 1.54 (range, 2-8) on day 3 after surgery. Nineteen patients (79.2%) stated that they would have preferred more pain therapy. Conclusions: Patients undergoing eye enucleation report pain sensations in need of intervention in this university hospital. Thus, effective standardized pain treatment concepts are now a high priority to be established in an interdisciplinary manner containing standardized regimens and continuous regional procedures. Awareness of this problem in the medical team should be sharpened through targeted training and information.