The effect of intravenous and inhalational maintenance of anaesthesia on postoperative cognitive outcomes in elderly people

Postoperative cognitive worsening in seniors with an age above life expectancy: a prospective longitudinal study

BACKGROUND

The growing number of elderly patients in hospitals is a challenge for healthcare systems. The main objective is to measure the postoperative change in the cognitive status at hospital discharge and one year after discharge in elderly patients undergoing planned or deferrable surgery.

METHODS

We planned a prospective longitudinal study, single-center study: secondary care level hospital, enrolment from September 2018 to May 2019. We enroll elderly patients, aged above life expectancy in Italy, who underwent planned or deferrable surgery (men over 80.5 years old, women over 85.0 years old). In six months, we enrolled 76 eligible patients. We collected the scores of the clinical impairment scales Charlson Index, Barthel Index, and Six-Item Cognitive Impairment Test (6CIT). The primary endpoint was the postoperative worsening of the cognitive status at one-year follow-up. Secondary endpoints aimed to describe postoperative disabilities and complications, to investigate possible risk factors for cognitive worsening, and to measure the role of anesthesia in cognitive changes.

RESULTS

We recorded an increased rate of pathological 6CIT values during the hospitalization period, rising from 39.47% to 55.26% (McNemar test, P=0.007), and this rate was still increased at 55.56% (P=0.021) one year after discharge. Anesthesia did not show any significant harmful effect on cognitive status. The preoperative hemoglobin value seems to be a risk factor for cognitive status and one-year mortality.

CONCLUSIONS

Elderly patients had a significantly worse 6CIT value after planned surgery, which may derive in part from age and in part from hospitalization. It is difficult to determine if general anesthesia alone has no harmful effects on cognitive performance in patients at discharge and one year later. Further data are necessary.

Histone deacetylase 9 plays a role in sevoflurane-induced neuronal differentiation inhibition by inactivating cAMP-response element binding protein transcription and inhibiting the expression of neurotrophin-3

Postoperative cognitive decline (POCD) is a common and serious complication following anesthesia and surgery; however, the precise mechanisms of POCD remain unclear. Our previous research showed that sevoflurane impairs adult hippocampal neurogenesis (AHN) and thus cognitive function in the aged brain by affecting neurotrophin-3 (NT-3) expression; however, the signaling mechanism involved remains unexplored. In this study, we found a dramatic decrease in the proportion of differentiated neurons with increasing concentrations of sevoflurane, and the inhibition of neural stem cell differentiation was partially reversed after the administration of exogenous NT-3. Understanding the molecular underpinnings by which sevoflurane affects NT-3 is key to counteracting cognitive dysfunction. Here, we report that sevoflurane administration for 2 days resulted in upregulation of histone deacetylase 9 (HDAC9) expression, which led to transcriptional inactivation of cAMP-response element binding protein (CREB). Due to the colocalization of HDAC9 and CREB within cells, this may be related to the interaction between HDAC9 and CREB. Anyway, this ultimately led to reduced NT-3 expression and inhibition of neural stem cell differentiation. Furthermore, knockdown of HDAC9 rescued the transcriptional activation of CREB after sevoflurane exposure, while reversing the downregulation of NT-3 expression and inhibition of neural stem cell differentiation. In summary, this study identifies a unique mechanism by which sevoflurane can inhibit CREB transcription through HDAC9, and this process reduces NT-3 levels and ultimately inhibits neuronal differentiation. This finding may reveal a new strategy to prevent sevoflurane-induced neuronal dysfunction.

Association between post-operative delirium and use of volatile anesthetics in the elderly: A real-world big data approach

STUDY OBJECTIVE

Early post-operative delirium is a common perioperative complication in the post anesthesia care unit. To date it is unknown if a specific anesthetic regime can affect the incidence of delirium after surgery. Our objective was to examine the effect of volatile anesthetics on post-operative delirium.

DESIGN

Single Center Observational Study.

SETTING

Post Anesthesia Care Units at a German tertiary medical center.

PATIENTS

30,075 patients receiving general anesthesia for surgery.

MEASUREMENTS

Delirium was assessed with the Nursing Delirium Screening Scale at the end of the recovery period. Subgroup-specific effects of volatile anesthetics on post-operative delirium were estimated using generalized-linear-model trees with inverse probability of treatment weighting. We further assessed the age-specific effect of volatiles using logistic regression models.

MAIN RESULTS

Out of 30,075 records, 956 patients (3.2%) developed delirium in the post anesthesia care unit. On average, patients who developed delirium were older than patients without delirium. We found volatile anesthetics to increase the risk (Odds exp. (B) for delirium in the elderly 1.8-fold compared to total intravenous anesthesia. Odds increases with unplanned surgery 3.0-fold. In the very old (87 years or older), the increase in delirium is 6.2-fold. This result was confirmed with internal validation and in a logistic regression model.

CONCLUSIONS

Our exploratory study indicates that early postoperative delirium is associated with the use of volatile anesthetics especially in the sub-cohort of patients aged 75 years and above. Further studies should include both volatile and intravenous anesthetics to find the ideal anesthetic in elderly patients.

A comparison of postoperative respiratory complications associated with the use of desflurane and sevoflurane: a single-centre cohort study

Sevoflurane and desflurane are the most commonly used volatile anaesthetics for maintenance of anaesthesia. In this study, we aimed to evaluate the relationship between choice of volatile anaesthetic and early postoperative respiratory complications, and to address a critical knowledge gap in safety outcomes between these two commonly used agents. We performed a retrospective analysis of adult (non-cardiac surgery) patients who received sevoflurane or desflurane for the maintenance of general anaesthesia at our institution between 2005 and 2018. We evaluated the association between desflurane exposure (when compared with sevoflurane) and the primary outcome of postoperative respiratory complications, defined by early post-extubation desaturation (S_p O₂  < 90%) or re-intubation within 7 days postoperatively. Multivariable regression analyses were performed and adjusted for confounding factors, including patient, anaesthetic and surgical factors. Propensity matched, interaction and sub-group analyses were performed to assess outcomes in high-risk groups: morbidly obese (BMI > 35 kg.m^-2 ); elderly (age > 65 years); and high risk of respiratory complications as well as the primary outcome at 24 h. Desflurane was used for 23,830 patients and sevoflurane for 84,608 patients. Patients exposed to desflurane did not demonstrate a reduced risk of postoperative respiratory complications when compared with sevoflurane (adjusted odds ratio 0.99, 95%CI 0.94-1.04, p = 0.598). These findings were consistent across all sub-groups of high-risk patients and in the propensity score matched cohort. In summary, desflurane use was not associated with reduced postoperative respiratory complications when compared with sevoflurane. In the context of environmental and cost concerns with volatile anaesthetic agents, our study provides important data to support organisational decisions regarding the use of desflurane.

Characterization of DNA hydroxymethylation in the hypothalamus of elderly mice with post-operative cognitive dysfunction

Post-operative cognitive dysfunction (POCD) is a common syndrome characterized by perioperative cerebral damage in elderly patients, including cognitive impairment and memory loss. Recent studies have revealed that anesthesia is one of the key causes of POCD. Ubiquitin-like with PHD and ring finger domains 2 (Uhrf2) has been reported to play a crucial role in regulating DNA methylation and hydroxymethylation, which are closely connected with memory building and erasure. However, whether narcotic drugs can affect Uhrf2 to impact on DNA methylation and hydroxymethylation in POCD is poorly understood. In this study, a POCD model was established in elderly mice through sevoflurane treatment, and these mice were found to have compromised levels of global DNA 5'-hydroxymethylcytosine (5hmC) and Uhrf2 in the hippocampus and the amygdaloid nucleus, when compared with non-POCD and control mice. The results of immunoprecipitation and quantitative PCR revealed that 5hmC modification of the promoters of genes associated with neural protection and development, such as glial cell-derived neurotrophic factor, brain derived neurotrophic factor, glucocorticoid receptor and acyl-CoA sythetase short chain family member 2, was reduced in the hippocampus of POCD mice when compared with non-POCD and control mice. Taken together, the findings of the present study suggest that loss of 5hmC, in the hippocampus and the amygdaloid nucleus modulated by Uhrf2 suppression, may result in the learning and memory ability impairment seen in mice with POCD.