Perioperative Plasma Concentrations of Stable Nitric Oxide Products Are Predictive of Cognitive Dysfunction After Laparoscopic Cholecystectomy

Research Progress on the Role of Inflammatory Mechanisms in the Development of Postoperative Cognitive Dysfunction

Postoperative cognitive dysfunction (POCD), as one of the common postoperative complications, mainly occurs after surgery and anesthesia, especially in the elderly. It refers to cognitive function changes such as decreased learning and memory ability and inability to concentrate. In severe cases, there could be personality changes and a decline in social behavior. At present, a great deal of research had been carried out on POCD, but its specific mechanism remains unclear. The release of peripheral inflammation-related factors, the degradation and destruction of the blood-brain barrier, the occurrence of central inflammation, and the neuronal apoptosis and synaptic loss could be promoted by neuroinflammation indicating that inflammatory mechanisms may play key roles in the occurrence of POCD.

Exogenous hydrogen sulfide alleviates surgery-induced neuroinflammatory cognitive impairment in adult mice by inhibiting NO signaling

Background

To investigate the effect and mechanisms of exogenous hydrogen sulfide in surgery-induced neuroinflammatory cognitive dysfunction.

Methods

C57BL/6 J male mice (n = 140) were used and randomly divided into seven groups: the sham group, surgery group, GYY4137 group, L-NAME group, surgery+GYY4137 group, surgery +L-NAME group, and surgery+GYY4137 + L-NAME group. After the interventions, open field tests (OFT) and the Morris water maze (MWM) test were conducted to evaluate learning and memory abilities in the mice. ELISAs, nitrate reductase assays, and Western blots (WB) were conducted to evaluate interleukin-1 beta (IL-1β), tumor necrosis factor-alpha (TNF-α), nitric oxide (NO), inducible nitric oxide synthase (iNOS), malondialdehyde (MDA), and antioxidant enzyme superoxide dismutase (SOD) levels. Furthermore, the expression level of microglial marker ionized calcium binding adaptor molecule 1 (IBA) in the hippocampal CA1 and CA3 areas was detected by an immunohistochemical (IHC) assay and apoptotic cells were observed using terminal deoxynucleotidyl transferase dUTP end-labeling (TUNEL) staining kits.

Results

We found that surgery induced neuroinflammatory cognitive dysfunction, oxidative stress, microglial activation, and cell apoptosis in the hippocampus. Moreover, following surgery, NO and iNOS levels were elevated in the hippocampus. Notably, all the effects caused by surgery were reversed by the H₂S donor GYY4137 or the iNOS inhibitor N(gamma)-nitro-L-arginine methyl ester (L-NAME). However, the combined application of GYY4137 and L-NAME was not superior to treatment with either agent alone and the effect of GYY4137 was similar to that of L-NAME.

Conclusion

The long-acting hydrogen sulfide donor GYY4137 had an ability to reversed the cognitive deficits and inflammation caused by carotid artery exposure surgery. This implies that NO signaling pathways might participate in this process. These results indicate that exogenous H₂S may be a promising therapy for POCD.

Post-Operative Cognitive Dysfunction: An exploration of the inflammatory hypothesis and novel therapies

Post-Operative Cognitive Dysfunction (POCD) is a highly prevalent condition with significant clinical, social and financial impacts for patients and their communities. The underlying pathophysiology is becoming increasingly understood, with the role of neuroinflammation and oxidative stress secondary to surgery and anaesthesia strongly implicated. This review aims to describe the putative mechanisms by which surgery-induced inflammation produces cognitive sequelae, with a focus on identifying potential novel therapies based upon their ability to modify these pathways.

Neurologic Complications in Noncardiac Surgery

In this article, the incidence of nervous system injuries associated with noncardiac surgery is reviewed briefly. In general, these can be divided into injuries that are clinically apparent (eg, stroke or peripheral nerve damage), which may generally be detectable on clinical examination, and more subtle forms of brain injury (eg, personality changes and postoperative cognitive dysfunction), injuries that are primarily detected by neuropsychological testing.

Thinking through postoperative cognitive dysfunction: How to bridge the gap between clinical and pre-clinical perspectives

Following surgery, patients may experience cognitive decline, which can seriously reduce quality of life. This postoperative cognitive dysfunction (POCD) is mainly seen in the elderly and is thought to be mediated by surgery-induced inflammatory reactions. Clinical studies tend to define POCD as a persisting, generalised decline in cognition, without specifying which cognitive functions are impaired. Pre-clinical research mainly describes early hippocampal dysfunction as a consequence of surgery-induced neuroinflammation. These different approaches to study POCD impede translation between clinical and pre-clinical research outcomes and may hamper the development of appropriate interventions. This article analyses which cognitive domains deteriorate after surgery and which brain areas might be involved. The most important outcomes are: (1) POCD encompasses a wide range of cognitive impairments; (2) POCD affects larger areas of the brain; and (3) individual variation in the vulnerability of neuronal networks to neuroinflammatory mechanisms may determine if and how POCD manifests itself. We argue that, for pre-clinical and clinical research of POCD to advance, the effects of surgery on various cognitive functions and brain areas should be studied. Moreover, in addition to general characteristics, research should take inter-relationships between cognitive complaints and physical and mental characteristics into account.

Nitric oxide index is not a predictor of cognitive dysfunction following laparotomy

STUDY OBJECTIVE

To determine the associations between postoperative cognitive dysfunction (POCD) and plasma concentrations of stable nitric oxide products [nitric oxide index (NOi)].

DESIGN

Prospective study.

SETTING

Academic hospital.

PATIENTS

28 ASA physical status I, II, and III physical status patients undergoing major non-cardiac surgery.

INTERVENTIONS

Cognitive assessment was performed preoperatively and postoperatively at 4 days (early) and 6 weeks (late).

MEASUREMENTS

Serial measurements of plasma NOi were recorded.

MAIN RESULTS

Early POCD with a deficit in one cognitive domain was present in 18 patients (64%), and in 8 patients (28%) with deficits in two or more cognitive domains. Late POCD was evident in three patients (20%) who had a deficit in one domain. Eight patients were lost to late follow-up. There was no difference in baseline or subsequent serum concentrations of NOi between those who showed early and late POCD and those who showed no POCD.

CONCLUSION

Factors other than nitric oxide-mediated injury is responsible for POCD following major non-cardiac surgery.

Postoperative cognitive dysfunction: computerized and conventional tests showed only moderate inter-rater reliability

PURPOSE

The incidence of postoperative cognitive dysfunction (POCD) depends on the test battery and calculation method used. The measurements may be performed with a paper and pencil test battery or with a computerized test battery. The objective of this study was to measure the incidence and congruence of POCD by comparing a computerized test battery with a paper and pencil test battery in the same patient population.

METHODS

In total, 67 patients were included: 30 consecutive in-patients undergoing surgery under general anesthesia and 37 non-surgical out-patients as control. Patients were tested with a paper and pencil test battery and a computerized test battery on inclusion in the study and 7 days later. Both test batteries covered the cognitive domains: visual attention, visual learning, memory, and speed of processing.

RESULTS

The computerized test battery classified 10.0% (95% CI 3.5-25.6%) of the patients as suffering from POCD whereas the paper and pencil test battery classified 30.0% (95% CI 16.7-47.9%) as suffering (95% CI for difference 3.9-36.5%, P = 0.03). The inter-rater reliability between both test batteries showed moderate agreement (Cohen's kappa of 0.41). All patients identified by use of the computerized test battery were also identified with the paper and pencil test battery. The paper and pencil test battery identified 6 additional cases.

CONCLUSION

In our study we demonstrated that the incidence of POCD measured with computerized test battery and paper and pencil test battery showed moderate inter-rater reliability. Use of neuropsychological test batteries theoretically covering the same cognitive domains does not automatically lead to the same classification of POCD.

Paravertebral block: new benefits from an old procedure

PURPOSE OF REVIEW

Paravertebral blocks are becoming increasingly popular, especially as an anesthetic adjunct for breast procedures. New reports suggest additional reasons for adding this block to the anesthetic armamentarium.

RECENT FINDINGS

Recent studies demonstrate a benefit from preoperative placement of a paravertebral block, not only in reducing acute postoperative pain, but also statistically significant reductions in the percentage of patients that develop chronic postsurgical pain 1 year after surgery. Another study found that the breast-cancer recurrence rate at 36 months after surgery was lower in the paravertebral group compared with the general anesthesia-only group of patients.

SUMMARY

Paravertebral blocks are a well established option to provide anesthesia and postoperative analgesia during breast surgery. Recent studies suggest additional benefits to this procedure. Not only is acute pain better controlled, but the development of chronic mastectomy pain syndrome and recurrence of cancer may be reduced by preoperative placement of paravertebral block. These studies provide additional reasons why this block should be considered as part of the anesthetic for breast surgery.

The associations between severity of early postoperative pain, chronic postsurgical pain and plasma concentration of stable nitric oxide products after breast surgery

In this study, we compared the effects of two analgesic regimens on perioperative nitric oxide index (NOx) and the likelihood of subsequent development of chronic postsurgical pain (CPSP) after breast surgery and sought to determine the association among early postoperative pain, NOx, and the likelihood of subsequent development of CPSP. Twenty-nine consecutive ASA I or II patients undergoing breast surgery with axillary clearance were randomly allocated to one of two groups. Patients in group S (n = 15) received a standard intraoperative and postoperative analgesic regimen (morphine sulfate, diclofenac, dextropropoxyphene hydrochloride + acetaminophen prn). Patients in group N (n = 14) received a continuous paravertebral block (for 48 h) and acetaminophen and parecoxib (followed by celecoxib up to 5 days). Visual analog scale pain scores at rest and on arm movement were recorded regularly until the fifth postoperative day. A telephone interview was conducted 10 wk postoperatively. The McGill Pain Questionnaire was used to characterize pain. NOx was estimated preoperatively, at the end of surgery, 30 min and 2, 4, 12, 24, 48 h postoperatively. Twelve (80%) patients in group S and no patient in group N developed CPSP (P = 0.009). Compared with patients with a pain rating index > or =1 (n = 18) 10 wk postoperatively, patients with a pain rating index = 0 (n = 11) had lesser visual analog scale pain scores on movement at each postoperative time point from 30 min until 96 h postoperatively (P < 0.005) and at rest 30 min (0.6 +/- 1.5 versus 30.2 +/- 26.8; P = 0.004), 4 h (2.3 +/- 7.5 versus 19.0 +/- 25.8; P = 0.013), 8 h (4.4 +/- 10.2 versus 21.4 +/- 27.0; P = 0.03) and 12 h (0.7 +/- 1.2 versus 15.4 +/- 27.0; P = 0.035) postoperatively. NOx values were greater in group N compared with group S 48 h postoperatively (40.6 +/- 20.1 versus 26.4 +/- 13.5; P = 0.04).

Postoperative Cognitive Dysfunction After Cardiac Surgery

Prolonged postoperative cognitive dysfunction (POCD) is reported to occur frequently after cardiac surgery. However, it is rarely assessed in routine clinical practice and receives little attention. Although the cerebral consequences of cardiopulmonary bypass have been measured clinically, insights into the resulting molecular and pathologic events within the brain have only begun to be investigated. POCD is likely to impair quality of life and constitutes a large burden on society when elderly patients prematurely lose their independence. Numerous studies have reported that neurocognitive deficit is associated with heightened mortality, increased length of hospital stay, and discharge to a nursing home. This is linked with a tremendous demand for health-care resources. Because of the magnitude of the clinical problem, serious consideration must be directed toward understanding its etiology and the development of neuroprotective strategies. Clearly identifying the mechanisms of POCD is challenging. The purpose of this review is to discuss recent developments in our understanding of the pathophysiologic mechanisms, prevention, and treatments that have been designed to ameliorate brain dysfunction after cardiac surgery.