General anesthesia for surgery influences melatonin and cortisol levels

Microbiota-gut-brain axis in perioperative neurocognitive and depressive disorders: Pathogenesis to treatment

An increasing number of people undergo anesthesia and surgery. Perioperative neurocognitive and depressive disorders are common central nervous system complications with similar pathogeneses. These conditions pose a deleterious threat to human health and a significant societal burden. In recent years, numerous studies have focused on the role of the gut microbiota and its metabolites in the central nervous system via the gut-brain axis. Its involvement in perioperative neurocognitive and depressive disorders has attracted considerable attention. This review aimed to elucidate the role of the gut microbiota and its metabolites in the pathogenesis of perioperative neurocognitive and depressive disorders, as well as the value of targeted interventions and treatments.

Effects of general versus regional anaesthesia on circadian melatonin rhythm and its association with postoperative delirium in elderly patients undergoing hip fracture surgery: study protocol for a prospective cohort clinical trial

INTRODUCTION

Postoperative delirium (POD) is a common neurological complication after hip fracture surgery and is associated with high morbidity and mortality in elderly patients. Although the specific mechanism of POD remains unclear, circadian rhythm disruptions have recently drawn increased attention. To date, only limited postoperative time points of plasma melatonin level measurements were recorded in previous studies, and such data cannot represent a comprehensive melatonin rhythm. The process of anaesthesia (either general anaesthesia (GA) or regional anaesthesia (RA)) is known to influence the melatonin rhythm. However, how these two anaesthesia methods differently affect the postoperative melatonin rhythm is still unknown. Therefore, we hypothesise that RA may attenuate the disruption of the melatonin rhythm, which might decrease the incidence of POD in elderly patients undergoing hip surgery.

METHODS AND ANALYSIS

In this prospective cohort clinical trial, 138 patients scheduled for hip fracture surgery will be divided into two groups to receive either GA or RA. The primary aim is to compare the circadian rhythm of melatonin secretion between the two groups and explore its association with the incidence of POD.

ETHICS AND DISSEMINATION

The study has been approved by the Medical Science Research Ethics Committees of Beijing Jishuitan Hospital (JLKS201901-04). The results of the study will be published in peer-reviewed international journals.

TRIAL REGISTRATION NUMBER

ChiCTR1900027393.

[Effect of general anesthesia on postoperative melatonin secretion in 4-to 6-year-old children with snoring]

OBJECTIVE

To evaluate the effect of general anesthesia on postoperative melatonin secretion in 4-to 6-year-old children with snoring.

METHODS

Twenty children with snoring aged 4-6 years of either gender (ASA grade Ⅰ and Ⅱ) were selected for adenoidectomy.Before, during and 3 days after the operation, salivary melatonin levels of the children were measured at 11 selected time points (T1-T11).The illumination intensity and body temperature of the children were recorded at each time point of measurement.The sleep time of the children in 3 days after the operation was recorded, and postoperative pain scores (FLACC) and Riker and Rehabilitation Quality Rating Scale-15(QoR-15) scores were assessed.Sleep Apnea Life Quality Evaluation Questionnaire (OSA-18) was used to evaluate postoperative recovery of the children at 28 days after the operation.The incidence of major adverse events of the children during hospitalization was recorded.

RESULTS

No significant difference was found in baseline salivary melatonin level among the 20 children before the operation.Salivary melatonin level at 7 am after the operation (T8) was significantly lowered as compared with that before the surgery (T4)(P < 0.05) but recovered at 7 am on the second day after the surgery (T11);salivary melatonin levels at T4, T8, and T11 exceeded 3 pg/mL on the third day.No significant difference was found in illumination intensity or body temperature across the time points when melatonin level was measured.The children showed no significant changes in FLACC score, Riker score or QOR- 15 score after the operation, but the OSA-18 score was significantly lowered after the operation (P < 0.05).None of the 20 children had such adverse events as respiratory depression, sinus bradycardia, sinus tachycardia, hypertension, hypotension, nausea or vomiting during hospitalization.

CONCLUSIONS

In preschool children with snoring, general anesthesia affects but does not inhibit melatonin secretion on the first night after surgery, and minor surgeries under general anesthesia in the morning do not cause significant changes in melatonin secretion to cause disturbance of the circadian rhythm in these children.

Evaluation of Presurgical Serum Cortisol Level in Patients Undergoing Major Maxillofacial Surgery

Background:

Stress is an integral part of life. Anxiety levels may increase when it comes to being treated surgically due to road traffic accidents causing facial trauma, other pathologies or burns. The stress that is caused during a surgical procedure as well as during the treatment in debilitated patients or traumatic conditions is bound to cause disturbance in the metabolic and physiologic levels of cortisol. Therefore, a study was carried out to determine the cortisol levels just prior to surgery on the day of operation to quantify the stress levels and also aid in any preanesthetic medication changes for the patient undergoing maxillofacial surgery.

Aim:

To evaluate and compare pre-surgical serum cortisol levels in patients undergoing major maxillofacial surgery under general anaesthesia.

Objective:

To evaluate the serum cortisol level of patient 3 days prior to surgery, on the day of surgery and to compare and evaluate the difference seen in both the obtained values.

Methods:

A prospective, randomized, in- vivo study was carried out in the Department of Oral and Maxillofacial Surgery at a teaching dental hospital. A total of 32 patients were included in this study. Inclusion and Exculsion criteria was made along with pre-opertive assessment of the patient, informed consent was obtained from all patients involved in the study. Patient blood sample, at 8 am three days prior to surgery and on the day of surgery and sent for laboratory investigations.

Result:

Participants in this clinical study underwent treatment of various ailments like facial trauma, and miscellaneous pathologies like Dentigerous Cyst, Oral submucosa fibrosis, Osteomyelitis, Benign Tumor and Orthognathic surgery. The anxiety of the patients were assessed by serum cortisol level preoperatively and on the day of operation. A total of 32 patients, 26 male and 06 female were included in the study. There was statistically highly significant difference seen between the mean values obtained three days prior to surgery and on the day of surgery.

Conclusion:

We have concluded from this study that the serum cortisol level shows significant increase on the day of surgery. A future study can focus on association between increased levels of serum cortisol and postoperative wound healing where patients can be divided into two groups one receiving pre-operative stress reduction protocol and other not receiving the same.

Internal clock and the surgical ICU patient

PURPOSE OF REVIEW

The alteration of circadian rhythms in the postoperative period has been demonstrated to influence the outcomes. With this narrative review we would revise how anesthesia, surgery and intensive care can interfere with the circadian clock, how this could impact on the postsurgical period and how to limit the disruption of the internal clock.

RECENT FINDINGS

Anesthesia affects the clock in relation to the day-time administration and the type of anesthetics, N-methyl-D-aspartate receptor antagonists or gamma-aminobutyric acid receptors agonists. Surgery causes stress and trauma with consequent alteration in the circadian release of cortisol, cytokines and melatonin. ICU represents a further challenge for the patient internal clock because of sedation, immobility, mechanical ventilation and alarms noise.

SUMMARY

The synergic effect of anesthesia, surgery and postoperative intensive care on circadian rhythms require a careful approach to the patient considering a role for therapies and interventions aimed to re-establish the normal circadian rhythms. Over time, approach like the Awakening and Breathing Coordination, Delirium Monitoring and Management, Early Mobility and Family engagement and empowerment bundle can implement the clinical practice.

Comparison of Morning and Evening Operation Under General Anesthesia on Intraoperative Anesthetic Requirement, Postoperative Sleep Quality, and Pain: A Randomized Controlled Trial

OBJECTIVE

Postoperative sleep disorders can cause serious adverse effects on postoperative outcomes. The purpose of our study was to compare the effects of the timing of surgery under general anesthesia on intraoperative anesthetic drug requirements, postoperative sleep quality and pain in patients.

MATERIALS AND METHODS

Eighty-four patients who underwent selective laparoscopic abdominal surgeries under general anesthesia were randomly assigned to the Day Group (8:00-12:00) or the Night Group (18:00-22:00). The portable sleep monitor (PSM) was used to determine sleep quality on the night before surgery (Sleep-preop), the first night after surgery (Sleep POD 1), and the third night after surgery (Sleep POD 3). The visual analog scale (VAS) was used to evaluate postoperative pain scores and the Athens Insomnia Scale (AIS) was used for assessing insomnia symptoms. The total dose of general anesthetics required and adverse effects after surgery were also assessed.

RESULTS

Compared to Sleep-preop, patients presented with a lower sleep efficiency and a higher AIS score during Sleep POD 1 and Sleep POD 3. Furthermore, the Night Group had a significantly lower proportion of rapid eye movement sleep, stable sleep, and unstable sleep than did the Day Group at Sleep POD 1 and Sleep POD 3. The dosage of propofol and remifentanil required in the Day Group was significantly higher than that in the Night Group. Furthermore, patients in the Day Group had better pain relief, with a lower VAS score at 1, 6, 12, and 24 hours after surgery. The incidences of postoperative nausea and vomiting and dizziness were significantly higher in the Night Group than those in the Day Group.

CONCLUSION

Morning operations required a higher dose of anesthetic drugs than did evening operations, which may be related to the circadian rhythm. The degree of postoperative sleep disorders was greater when the operation was performed in the evening than in the morning, which was also associated with increased pain perception and increased incidence of postoperative adverse effects. Thus, our results suggest that patients with hyperalgesia and sleep disorders may benefit from operations performed in the morning.

Endocrine-Metabolic Response in Patients Undergoing Multiple Body Contouring Surgeries After Massive Weight Loss

BACKGROUND

The endocrine-metabolic response to trauma is directly related to its magnitude, but little is known about the adverse effects of combined surgical procedures on morbidity.

OBJECTIVES

The authors sought to evaluate risk factors by measuring the endocrine-metabolic response in patients who underwent multiple body-contouring surgeries after massive weight loss.

METHODS

This prospective, randomized, interventional study included 46 massive weight loss patients who experienced a weight loss >30% of their body mass index (BMI) and were referred for body contouring surgery. Patients were randomly allocated to the control group (n = 10) or intervention group (n = 36), which in turn was divided into 3 subgroups (n = 12, each) according to BMI, surgical time, and scar length values. Blood samples were collected from all patients at different time points to assess biological stress markers.

RESULTS

Levels of IL-6 in patients in the higher ranges of BMI and operating time and with more extensive scar length were significantly higher in the immediate postoperative period compared with baseline. Concentrations of noradrenaline were significantly higher 24 hours after surgery compared with baseline only in patients in the higher range of operating time. A higher level of IL-6 at 72 hours after surgery compared with baseline was associated with more extensive scar length. Levels of other biological stress markers did not significantly differ.

CONCLUSIONS

The combination of surgical procedures did not significantly affect the concentrations of most biological stress markers. The variable of operating time most influenced increase in plasma concentrations of stress markers.

LEVEL OF EVIDENCE: 1

Effects of surgery start time on postoperative cortisol, inflammatory cytokines, and postoperative hospital day in hip surgery: Randomized controlled trial

BACKGROUND

The aim of this study was to compare morning surgery (Group A), characterized by high cortisol levels, with afternoon surgery (Group B), characterized by low cortisol levels, with respect to cortisol, inflammatory cytokines (interleukin [IL]-6, IL-8), and postoperative hospital days (POHD) after hip surgery.

METHODS

The study was conducted in a single center, prospective, randomized (1:1) parallel group trial. Patients undergoing total hip replacement or hemiarthroplasty were randomly divided into two groups according to the surgery start time: 8 AM (Group A) or 1-2 PM (Group B). Cortisol and cytokine levels were measured at 7:30 AM on the day of surgery, before induction of anesthesia, and at 6, 12, 24, and 48 hours (h) after surgery. Visual analogue scale (VAS) and POHD were used to evaluate the clinical effect of surgery start time. VAS was measured at 6, 12, 24, and 48 h postoperatively, and POHD was measured at discharge.

RESULTS

In total, 44 patients completed the trial. The postoperative cortisol level was significantly different between the two groups. (24 h, P < .001; 48 h, P < .001). The percentage of patients whose level returned to the initial level was higher in Group B than in Group A (P < .001). Significant differences in IL-6 levels were observed between the two groups at 12, 24, and 48 h after surgery (P = .015; P = .005; P = .002), and in IL-8 levels at 12 and 24 h after surgery (P = .002, P < .001). There was no significant difference between the two groups in VAS and POHD. However, only three patients in Group A were inpatients for more than 3 weeks (P = .233).

CONCLUSIONS

Afternoon surgery allowed for more rapid recovery of cortisol to the baseline level than morning surgery, and IL-6 and IL-8 were lower at 1-2 days postoperatively. The results of this study suggest that afternoon surgery may be considered in patients with postoperative delayed wound healing or inflammation because of the difference in cortisol, IL-6 and 8 in according to surgery start time.

CLINICAL TRIAL REGISTRATION NUMBER

NCT03076827 (ClinicalTRrial.gov).

Effect of anaesthetic agents on olfactory threshold and identification - A single blinded randomised controlled study

Background and Aims:

Anaesthetics are implicated in cognitive dysfunction, taste and odour deficits in the postoperative period. We aimed to assess the effect of isoflurane, sevoflurane, propofol and regional anaesthesia on the olfactory threshold, olfactory identification and endocrine regulation of associative memory in the postoperative period.

Methods:

In this observer-blinded randomised controlled study, 164 patients (>50 years) with the American Society of Anesthesiologists I and II status were randomised into one of four groups to receive regional anaesthesia, general anaesthesia with sevoflurane, general anaesthesia with isoflurane and total intravenous anaesthesia with propofol. Hindi Mental State Examination, olfactory threshold and olfactory identification were tested at 12 h preoperatively (T0), at 3 h postoperatively (T1) and at the time of discharge or postoperative day 3 (T2). In addition, serum melatonin levels were estimated at T0 and T1. The olfactory threshold was tested with n-butyl alcohol and olfactory identification with the University of Pennsylvania Smell Identification Test (UPSIT). Data were analysed using the one-way analysis of variance, Kruskal-Wallis or Mann-whitney tests.

Results:

The olfactory identification scores were lower with patients receiving sevoflurane-based anaesthesia at 3 h postoperatively (T1) when compared to preoperative (T0) (median 19.5 vs. 22; P = 0.01). This was accompanied by a significant postoperative reduction of plasma melatonin levels in sevoflurane group when compared to other groups (17.34 ± 4.8 pg/ml vs 23.2 ± 3.5 pg/ml; P < 0.001).

Conclusion:

Sevoflurane was associated with short-term olfactory identification impairment with a concomitant reduction in melatonin levels illustrating a possible humoral mechanism.

Comparing the Effects of Isoflurane-Sufentanil Anesthesia and Propofol-Sufentanil Anesthesia on Serum Cortisol Levels in Open Heart Surgery with Cardiopulmonary Bypass

Background

Major surgeries such as open-heart surgery with cardiopulmonary bypass are associated with a complexity of stress response leading to post-operative complications. Studies have confirmed that anesthesia can mitigate the surgically induced stress response.

Objectives

The aim of this study was to compare the effects of propofol and isoflurane, both supplemented with Sufentanil, on the stress response in coronary artery bypass graft surgery with cardiopulmonary bypass, using cortisol as a biochemical marker.

Methods

This double-blind randomized clinical trial was conducted on 72 patients who underwent coronary artery bypass grafting (CABG) with cardiopulmonary bypass meeting the inclusion criteria. The subjects were randomly divided into two groups of isoflurane (n = 36) and propofol (n = 36) both supplemented with sufentanil. Serum cortisol levels were measured and compared between the groups; 30 minutes before the surgery (T0), at the end of the cardiopulmonary bypass (T1), and 24 hours after the surgery (T2).

Results

Compared to the baseline (T0), at the end of cardiopulmonary bypass (T1), both groups demonstrated a decrease in plasma cortisol levels with no statistical significant difference (P = 0.4). At T2 measuring time point, the level of plasma cortisol significantly increased in both groups (P = 0.02), however this increase was less in the Isoflurane group.

Conclusions

In CABG with cardiopulmonary bypass, using plasma cortisol level as a measure, Isoflurane-Sufentanil significantly reduces the stress response to the surgery, when compared to propofol-Sufentanil.

Effect of Day and Night Desflurane Anaesthesia on Melatonin Levels in Rats

OBJECTIVE

The aim of this study is to investigate the effect of day and night administration of desflurane anaesthesia on melatonin levels in rats.

METHODS

Twenty-four 15-day-old rats were included in the study and were divided into four groups. The rats were anaesthetised between 19:00-01:00 (night group) and 07:00-13:00 (day group) with 5.7% desflurane concentration in 6 L min^-1 100% oxygen. 6 L min^-1 oxygen was administered to the control groups. At the end of 6 h of anaesthesia, blood samples were taken, and rats were sacrificed. Blood samples were centrifuged and melatonin levels from plasma samples were measured with radioimmunoassay.

RESULTS

There was a statistically significant difference between the groups (p=0.007). Between group day control and group night control there was a statistically significant difference (p=0.042). Further, there was a significant difference between group day control and night desfluran as well (p=0.024). We could not find any difference between other groups.

CONCLUSION

This study showed that 6 hours of 5.7% desflurane anaesthesia during day and night hours did not significantly change melatonin levels.

Effect of day/night administration of three different inhalational anesthetics on melatonin levels in rats

The nocturnal peak of melatonin can be altered after anesthesia and surgery. We aimed to examine the melatonin levels during the day and night after anesthesia with three commonly used inhalational anesthetics. Forty-eight male Wistar albino rats were randomized into eight groups. Rats were administered anesthesia between 7:00 am and 1:00 pm (day groups) or 7:00 pm and 1:00 am (night groups) for 6 hours. At the end of the anesthesia, blood samples were collected for assessing melatonin levels. Mean values of melatonin levels after 6 hours of anesthesia during daytime were 43.17±12.95 for control, 59.79±27.83 for isoflurane, 50.75±34.28 for sevoflurane and 212.20±49.56 pg/mL for desflurane groups. The night groups' mean melatonin levels were 136.12±33.20 for control, 139.85±56.29 for isoflurane, 117.48±82.39 for sevoflurane and 128.70±44.63 pg/mL for desflurane groups. Desflurane anesthesia between 7:00 am and 1:00 pm significantly increased melatonin levels (p<0.001). Sevoflurane and desflurane anesthesia between 7:00 pm and 1:00 am decreased the melatonin levels but there were no significant differences (p=0.904 and p>0.99, respectively). Isoflurane anesthesia did not significantly change melatonin levels during day or night (p=0.718 and p>0.99, respectively). Our results demonstrate that during daytime desflurane anesthesia can alter melatonin levels. Altered melatonin rhythm following inhalational anesthesia can be related to sleep disorders observed after anesthesia.

Influence of spinal and general anesthesia on the metabolic, hormonal, and hemodynamic response in elective surgical patients

Background

The aim of the study was to determine the significance of spinal anesthesia in the suppression of the metabolic, hormonal, and hemodynamic response to surgical stress in elective surgical patients compared to general anesthesia.

Material/Methods

The study was clinical, prospective, and controlled and it involved 2 groups of patients (the spinal and the general anesthesia group) who underwent the same surgery. We monitored the metabolic and hormonal response to perioperative stress based on serum cortisol level and glycemia. We also examined how the different techniques of anesthesia affect these hemodynamic parameters: systolic arterial pressure (AP), diastolic AP, heart rate (HR), and arterial oxygen saturation (SpO₂). These parameters were measured before induction on anesthesia (T1), 30 min after the surgical incisions (T2), 1 h postoperatively (T3) and 24 h after surgery (T4).

Results

Serum cortisol levels were significantly higher in the general anesthesia group compared to the spinal anesthesia group (p<0.01). Glycemia was significantly higher in the general anesthesia group (p<0.05). There was a statistically significant, positive correlation between serum cortisol levels and glycemia at all times observed (p<0.01). Systolic and diastolic AP did not differ significantly between the groups (p=0.191, p=0.101). The HR was significantly higher in the general anesthesia group (p<0.01). SpO₂ values did not differ significantly between the groups (p=0.081).

Conclusions

Based on metabolic, hormonal, and hemodynamic responses, spinal anesthesia proved more effective than general anesthesia in suppressing stress response in elective surgical patients.

Detection of recurrent Cushing's disease: proposal for standardized patient monitoring following transsphenoidal surgery

Transsphenoidal surgery (TSS) is first-line treatment for Cushing’s disease (CD), a devastating disorder of hypercortisolism resulting from overproduction of adrenocorticotropic hormone by a pituitary adenoma. Surgical success rates vary widely and disease may recur years after remission is achieved. Recognizing CD recurrence can be challenging; although there is general acceptance among endocrinologists that patients need lifelong follow-up, there are currently no standardized monitoring guidelines. To begin addressing this need we created a novel, systematic algorithm by integrating information from literature on relapse rates in surgically-treated CD patients and our own clinical experiences. Reported recurrence rates range from 3 to 47 % (mean time to recurrence 16–49 months), emphasizing the need for careful post-surgical patient monitoring. We recommend that patients with post-operative serum cortisol <2 µg/dL (measured 2–3 days post-surgery) be monitored semiannually for 3 years and annually thereafter. Patients with post-operative cortisol between 2 and 5 µg/dL may experience persistent or subclinical CD and should be evaluated every 2–3 months until biochemical control is achieved or additional treatment is initiated. Post-operative cortisol >5 µg/dL often signifies persistent disease and second-line treatment (e.g., immediate repeat pituitary surgery, radiotherapy, and/or medical therapy) may be considered. This follow-up algorithm aims to (a) enable early diagnosis and treatment of recurrent CD, thereby minimizing the detrimental effects of hypercortisolism, and (b) begin addressing the need for standardized guidelines for vigilant monitoring of CD patients treated by TSS, as demonstrated by the reported rates of recurrence.

Sleep disturbances and changes in urinary 6-sulphatoxymelatonin levels in patients with breast cancer undergoing lumpectomy

BACKGROUND

Sleep disturbances and changes in self-reported discomfort and melatonin secretion are common in the post-operative period. We aimed to study the distribution of sleep stages in the perioperative period and evaluate changes in secretion of the melatonin metabolite aMT6s and subjective parameters of sleepiness, pain, general well-being and fatigue in patients undergoing surgery for breast cancer.

METHODS

Twelve patients, 30-70 years, undergoing lumpectomy were included. Polysomnography was performed the night before surgery (PREOP), the night after (PO1) and 14 days after (PO14). Recordings were scored as awake, light-sleep, slow-wave sleep and rapid-eye-movement (REM) sleep. Sleep stages were analysed as % of total sleep time (TST). Self-reported discomfort was assessed using questions about the level of fatigue, well-being, pain and sleepiness. Urinary aMT6s was measured by radioimmunoassay.

RESULTS

There was significantly decreased REM sleep on PO1 (5.9% of TST) compared with PREOP (18.7% of TST) (P < 0.005). An increase in light sleep was observed on PO1 (68.4% of TST) compared with PREOP (55.0% of TST) (P < 0.05). No significant changes in TST, sleep latency, sleep period or total time awake were found. The observed sleep changes were normalised after 2 weeks. No significant changes were found in pain, well-being, fatigue or sleepiness. Night secretion of aMT6s showed a trend towards a decrease from PREOP to PO1 (P = 0.09) and normalisation on PO14 (P = 0.27 between PREOP and PO14).

CONCLUSION

Patients with breast cancer undergoing lumpectomy had significantly disturbed sleep architecture the night after surgery, and these changes were normalised after 2 weeks.

Perioperative plasma melatonin concentration in postoperative critically ill patients: its association with delirium

PURPOSE

Delirium is a common complication in postoperative critically ill patients. Although abnormal melatonin metabolism is thought to be one of the mechanisms of delirium, there have been few studies in which the association between alteration of perioperative plasma melatonin concentration and postoperative delirium was assessed.

MATERIALS

We conducted a prospective observational study to assess the association of perioperative alteration of plasma melatonin concentration with delirium in 40 postoperative patients who required intensive care for more than 48 hours. We diagnosed postoperative delirium using Confusion Assessment Method for the intensive care unit and measured melatonin concentration 4 times (before the operation as the preoperative value, 1 hour after the operation, postoperative day 1, and postoperative day 2).

RESULTS

Postoperative delirium occurred in 13 (33%) of the patients. Although there was no significant difference in preoperative melatonin concentration, Δ melatonin concentration at 1 hour after the operation was significantly lower in patients with delirium than in those without delirium (-1.1 vs 0 pg/mL, P = .036). After adjustment of relevant confounders, Δ melatonin concentration was independently associated with risk of delirium (odds ratio, 0.50; P = .047).

CONCLUSIONS

Delta melatonin concentration at 1 hour after the operation has a significant independent association with risk of postoperative delirium.

Day or night administration of ketamine and pentobarbital differentially affect circadian rhythms of pineal melatonin secretion and locomotor activity in rats

BACKGROUND

Surgery with general anesthesia disturbs circadian rhythms, which may lead to postoperative sleep disorders and delirium in patients. However, it is unclear how circadian rhythms are affected by different anesthetics administered at different times during the rest-activity cycle. We hypothesized that pentobarbital (an agonist at the γ-aminobutyric acid A receptors) and ketamine (an antagonist at the N-methyl-d-aspartate receptors) would have differential effects on circadian rhythms, and these effects would also be influenced by the time of their administration (the active versus resting phase).

METHODS

Rats were divided into 4 groups according to the anesthetic administered (pentobarbital or ketamine) and the timing of intraperitoneal administration (active/night phase or resting/day phase). Using online pineal microdialysis, we analyzed pineal melatonin secretion and locomotor activity rhythms in rats under a light/dark (12/12-hour) cycle for 5 days after anesthesia and microdialysis catheter implantation. The data were analyzed for rhythmicity by cosinor analysis.

RESULTS

Ketamine administered during the resting phase produced 65- and 153-minute phase advances, respectively, in melatonin secretion and locomotor activity rhythms on the first day after anesthesia. In contrast, ketamine administered during the active phase produced 43- and 235-minute phase delays. Pentobarbital had no effect on the phase of either melatonin secretion or locomotor activity, irrespective of the timing of administration. When administered during the active phase, both anesthetics decreased the amplitude of melatonin secretion on the day after anesthesia; when administered during the resting phase, however, neither anesthetic affected the amplitude. The amplitude of locomotor activity decreased in all animals for 3 days after anesthesia.

CONCLUSION

Ketamine has opposite phase-shifting effects on circadian rhythms according to the time of administration, whereas pentobarbital has no effect. Furthermore, both anesthetics decrease the postoperative amplitude of pineal melatonin secretion if administered during the active, but not the resting, phase of the 24-hour rest-activity cycle.

The effect of MELatOnin on Depression, anxietY, cognitive function and sleep disturbances in patients with breast cancer. The MELODY trial: protocol for a randomised, placebo-controlled, double-blinded trial

Introduction Breast cancer represents about one-third of all cancer diagnoses and accounts for about 15% of cancer deaths in women. Many of these patients experience depression, anxiety, sleep disturbances and cognitive dysfunction. This may adversely affect quality of life and also contribute to morbidity and mortality. Melatonin is a regulatory circadian hormone having, among others, a hypnotic and an antidepressive effect. It has very low toxicity and very few adverse effects compared with the more commonly used antidepressants and hypnotics. Methods and analysis The objective of this double-blind, randomised, placebo-controlled trial is to investigate whether treatment with oral melatonin has a prophylactic or ameliorating effect on depressive symptoms, anxiety, sleep disturbances and cognitive dysfunction in women with breast cancer. Furthermore, the authors will examine whether a specific clock-gene, PER3, is correlated with an increased risk of depressive symptoms, sleep disturbances or cognitive dysfunction. The MELODY trial is a prospective double-blinded, randomised, placebo-controlled trial in which the authors intend to include 260 patients. The primary outcome is depressive symptoms measured by the Major Depression Inventory. The secondary outcomes are anxiety measured by a Visual Analogue Scale, total sleep time, sleep efficiency, sleep latency and periods awake measured by actigraphy and changes in cognitive function measured by a neuropsychological test battery. Tertiary outcomes are fatigue, pain, well-being and sleep quality/quantity measured by Visual Analogue Scale and sleep diary and sleepiness measured by the Karolinska Sleepiness Scale. The PER3 genotype is also to be determined in blood samples.

Sevoflurane impairs post-operative olfactory memory but preserves olfactory function

BACKGROUND AND OBJECTIVE

The effect of anaesthesia on olfaction has not been systematically studied. Our aim is to compare the effects of general and regional anaesthesia on olfactory acuity and memory in the immediate post-operative period.

METHODS

Sixty adult patients with the American Society of Anesthesiologists I and II status scheduled for elective minor surgery were included. Exclusion criteria were smoking, alcoholism, psychiatric disease and recent or past airway infection with resulting hyposmia. Patients were randomly allocated to one of three groups (in the analysis, n = 16 in each group): epidural anaesthesia (group E), general anaesthesia with propofol (group P) and general anaesthesia with sevoflurane (group S) of 40-120 min duration. The evening before surgery, at 0.5 and at 3 h post-operatively olfactory acuity and memory were tested, along with blood sampling to measure plasma melatonin and oxytocin levels. Olfactory acuity was tested with successive dilutions of n-butyl-alcohol, and olfactory memory (interpretation of odours) with the University of Pennsylvania Smell Identification Test.

RESULTS

Patient characteristics did not differ between groups. Olfactory acuity was intact in all patients, before and after anaesthesia. Olfactory memory deteriorated in group S compared to groups P and E at both post-operative time-points. This was accompanied by a significant post-operative reduction of plasma melatonin levels in group S. Oxytocin levels remained constant in all groups.

CONCLUSION

Our results manifest a specific effect of sevoflurane on olfactory memory, not observed with neuraxial or total intravenous anaesthesia. The misinterpretation of odours in the immediate post-operative period by sevoflurane could be mediated by the decreased levels of melatonin.

Circadian aspects of post-operative morbidity and mortality

It has been well established that there exists a circadian concentration of cardiovascular, cerebrovascular and cardiopulmonary events. The aim was to describe aspects of circadian variation in relation to cardiovascular, cerebrovascular and thromboembolic diseases and to describe the literature concerning post-operative circadian disturbances. We also present the literature concerning circadian variation in post-operative morbidity and mortality. PubMed and the Cochrane database were searched for papers using a combination of 'circadian,''surgery,''post-operative,''mortality' and 'morbidity.' Eleven relevant studies were found, and seven of these were excluded due to the use of time of surgery and not time of morbidity or mortality as the main variable. The results from the four articles showed a circadian distribution of morbidity and mortality that mimics the one seen without surgery. There is a peak incidence of myocardial ischemia, fatal thromboembolism and sudden unexpected death in the morning hours. A circadian variation exists in post-operative morbidity and mortality. The observed circadian variation in post-operative morbidity and mortality may warrant a chronopharmacological approach to patients in the perioperative period. The underlying pathophysiological mechanisms should be the focus for future studies.

Effects of repeated surgical stress on daily changes of body core temperature in mice

Daily body core temperature rhythm has been known to become blunted for several days following intra-abdominal implantation of biotelemetry transmitters in small rodents and about a week is required for re-establishment of stable body core temperature oscillation. In the present study carried out on mice it was found that a repetition of the same minor surgical intervention (laparotomy) several days apart could speed up the stabilization of body temperature oscillations. Melatonin supplied with the drinking water continuously was found to speed up the return of stable daily body temperature rhythm further on consecutive laparotomies, while daily injections of methylprednisolone resulted in some delay in the development of stable body core temperature oscillations. It is concluded that in C57BL/6 mice possessing low plasma levels of melatonin exhibit an adaptive response to repeated stresses influencing the dynamics of daily body temperature rhythm.

[Biological rhythms for anaesthesia and intensive care]

Knowledge of biological rhythms has led to better understanding of the time-of-day dependent effects of anaesthetic drugs. These chronopharmacological effects are currently explained by the biological rhythms modulating the pharmacokinetic, toxic and pharmacodynamic parameters of these substances. Such effect has been described for general anesthetics, local anaesthetics, analgesics as well as for antibiotics. But recent data also highlight that general anaesthetics, probably part of their brain effects, also alter the regulation of biological rhythms, including the sleep-wake or the endogenous circadian temperature rhythms. This desynchronization of biological rhythms can led to disturbance of the circadian secretion of many substances, including hormones. Finally, biological rhythms have been also described with regard to physiology of pain and cardiovascular physiopathology. The concept of biological rhythm should be present in mind not only for the clinical management of patients but also for setting studies in the field of anaesthesia, pain and intensive care.

Disturbances in melatonin and core body temperature circadian rhythms after minimal invasive surgery

BACKGROUND

Sleep disturbances, fatigue and reduced general well-being frequently occur after minimal invasive surgery. The circadian rhythms of melatonin and core body temperature are central to the regulation of normal sleep. The aim of this study was to assess changes in these circadian rhythms after laparoscopic cholecystectomy.

METHODS

Twelve women were studied before and after laparoscopic cholecystectomy. The major urinary melatonin metabolite, 6-sulphatoxymelatonin (aMT6s), and the core body temperature were measured for 1 day before and 1 day after surgery. The basal and maximum secretion of aMT6s were determined, as well as the timing and amplitude of aMT6s and the temperature rhythm. The patients' rest-activity and calculated sleep parameters were assessed by actigraphy.

RESULTS

A significant delay in the timing of aMT6s rhythm was observed after surgery [median (range) peak time of aMT6s: after surgery, 05:49 h (02:57-08:23 h); before surgery, 04:32 h (02:18-06:49 h); P< or = 0.05]. The amplitude of the aMT6s rhythm was also significantly decreased after surgery [after surgery, 7.1 ng aMT6s/mg creatinine (1-15.9 ng); before surgery, 13.2 ng aMT6s/mg creatinine (2.9-22.7 ng); P< or = 0.005]. There was almost a 12-h phase delay of the core body temperature rhythm after surgery [peak time: before surgery, 17:39 h (15:17-22:06 h); after surgery, 05:14 h (03:24-21:43 h); P< or = 0.01].

CONCLUSIONS

Following laparoscopic cholecystectomy, there was a delay in the timing of the aMT6s rhythm and a decreased evening decline in the temperature rhythm.

Randomized clinical trial examining the effect of music therapy in stress response to day surgery

Background

Music therapy could reduce stress and the stress response. The aim of this study was to investigate the role of music therapy in alleviating stress during day surgery.

Methods

Sixty patients undergoing day surgery were randomized to one of three groups, each containing 20 patients. Before and during surgery, patients in group 1 listened to new age music and those in group 2 listened to a choice of music from one of four styles. Patients in group 3 (control group) heard the normal sounds of the operating theatre. Plasma levels of cortisol and subpopulations of lymphocytes were evaluated before, during and after operation.

Results

Plasma cortisol levels decreased during operation in both groups of patients who listened to music, but increased in the control group. Postoperative cortisol levels were significantly higher in group 1 than in group 2 (mean(s.d.) 14·21(6·96) versus 8·63(2·72) ng/dl respectively; P &lt; 0·050). Levels of natural killer lymphocytes decreased during surgery in groups 1 and 2, but increased in controls. Intraoperative levels of natural killer cells were significantly lower in group 1 than in group 3 (mean(s.d.) 212·2(89·3) versus 329·1(167·8) cells/µl; P &lt; 0·050).

Conclusion

Perioperative music therapy changed the neurohormonal and immune stress response to day surgery, especially when the type of music was selected by the patient.