Effects of glycemic regulation on chronic postischemia pain

Chronic post-ischemic pain (CPIP) a model of complex regional pain syndrome (CRPS-I): Role of oxidative stress and inflammation

Complex regional pain syndrome (CRPS) presents as a persistent and distressing pain condition often stemming from limb trauma or ischemia, manifesting as either CRPS-I (without initial nerve injury) or CRPS-II (accompanied by nerve injury). Despite its prevalence and significant impact on functionality and emotional well-being, standard treatments for CRPS remain elusive. The multifaceted nature of CRPS complicates the identification of its underlying mechanisms. In efforts to elucidate these mechanisms, researchers have turned to animal models such as chronic post-ischemic pain (CPIP), which mirrors the symptoms of CRPS-I. Various mechanisms have been proposed to underlie the acute and chronic pain experienced in CRPS-I, including oxidative stress and inflammation. Traditional treatment approaches often involve antidepressants, non-steroidal anti-inflammatory drugs (NSAIDs), and opioids. However, these methods frequently fall short of providing adequate relief. Accordingly, there is a growing interest in exploring alternative treatments, such as antioxidant supplementation, anti-inflammatory agents, and non-pharmacological interventions. Future research directions should focus on optimizing treatment strategies and addressing remaining gaps in knowledge to improve patient outcomes. This review aims to delve into the pathophysiological mechanisms implicated in the CPIP model, specifically focusing on oxidative stress and inflammation, with the ultimate goal of proposing innovative therapeutic strategies for alleviating the symptoms of CRPS-I.

Ward monitoring 4.0: real-time metabolic insights from continuous glucose monitoring into perioperative organ dysfunction

The now-routine clinical deployment of continuous glucose monitoring has demonstrated benefit in real-world settings. We make the case that continuous glucose monitoring can help re-examine, at scale, the role that (stress) hyperglycaemia plays in fuelling organ dysfunction after tissue trauma. Provided robust perioperative data do emerge, well-established continuous glucose monitoring technology could soon help transform the perioperative landscape.

The Relationship Between Pre-Operative Glycosylated Haemoglobin and Opioid Consumption After Caesarean Section in Women With Gestational Diabetes Mellitus

INTRODUCTION

Women with Gestational diabetes mellitus (GDM) had a higher need and consumption of analgesics than women without GDM. The preoperative level of HbA1c was associated with the postoperative consumption for analgesics in diabetic patients. This prospective observational study go further to investigate the relationship between the pre-operative HbA1c and the post-operative consumption for analgesics in women with GDM.

METHODS

Women with GDM and a singleton pregnancy undergoing elective cesarean section under combined spinal-epidural anaesthesia were divided into two groups based on pre-operative HbA1c: group HbA1c < 6% and group HbA1c ≥ 6%. Analgesics consumption, number of patient-controlled analgesia (PCA) compression, and pain scores in 6 hours and 24 hours post-operation were compared between the two groups. Then Pearson's correlation coefficient and a stepwise multivariate linear regression were performed to investigate possible independentpredictors of post-operative 24-hour sufentanil consumption.

RESULTS

Analgesics consumption was significantly lower (18.8 ± 0.4 vs 23.2 ± 4.3; 82.7 ± 2.4 vs 115.8 ± 17.4, P < 0.001), and number of PCA compressions was significantly less frequent (1 [1-2] vs 3 [1-5]; 5 [3-7] vs 7 [3-15], P < 0.001), and in group HbA1c < 6% than in group HbA1c ≥ 6% in 6 hours and 24 hours post-operation.The univariate analysis showed that sufentanil consumption at 24 hours post-operation was significantly related to pre-operative HbA1c (r = 0.338, P < 0.001) and parity (r = 0.184, P = 0.03) and was related to blood glucose management methods (r = 0.172, P = 0.043). Multivariate linear regression analysis showed that HbA1c was the independent factor related to post-operative 24-hour sufentanil consumption (adjusted r2 = 0.246, P < 0.001).

CONCLUSIONS

This study demonstrated that in pregnant women with GDM, the pre-operative HbA1c is independently related to the need for and consumption of analgesics in 24 hours after CS.

Animal Models of Complex Regional Pain Syndrome Type I

Complex regional pain syndrome (CRPS) is a chronic pain disorder characterized by spontaneous or evoked regionally-confined pain which is out of proportion to the initial trauma event. The disease can seriously affect the quality of the patients' life, increase the psychological burden, and cause various degrees of disability. Despite the awareness of CRPS among medical practitioners for over a century, its pathogenesis remains unclear, and the available treatment is still unsatisfactory. Effective animal models are the foundation of disease research, which is helpful in understanding the pathogenesis and an in-depth exploration of the appropriate therapeutic approaches. Currently, researchers have established a series of animal models of the disease. There are four main CRPSI animal models: chronic post-ischemic pain (CPIP) model, tibial fracture/cast immobilization model, passive transfer-trauma model, and the needlestick-nerve-injury (NNI) model. The modeling methods of these models are constantly improving over time. In preclinical studies, the interpretation of experimental results and the horizontal comparison between similar studies may be affected by the nature of the experimental animal breeds, sex, diet, and psychology. There is need to facilitate the choice of appropriate animal models and avoid the interference of the factors influencing animal models on the interpretation of research results. The review will provide a basic overview of the influencing factors, modeling methods, and the characteristics of CRPSI animal models.

Laboratory environmental factors and pain behavior: the relevance of unknown unknowns to reproducibility and translation

The poor record of basic-to-clinical translation in recent decades has led to speculation that preclinical research is "irreproducible", and this irreproducibility in turn has largely been attributed to deficiencies in reporting and statistical practices. There are, however, a number of other reasonable explanations of both poor translation and difficulties in one laboratory replicating the results of another. This article examines these explanations as they pertain to preclinical pain research. I submit that many instances of apparent irreproducibility are actually attributable to interactions between the phenomena and interventions under study and "latent" environmental factors affecting the rodent subjects. These environmental variables-often causing stress, and related to both animal husbandry and the specific testing context-differ greatly between labs, and continue to be identified, suggesting that our knowledge of their existence is far from complete. In pain research in particular, laboratory stressors can produce great variability of unpredictable direction, as stress is known to produce increases (stress-induced hyperalgesia) or decreases (stress-induced analgesia) in pain depending on its parameters. Much greater attention needs to be paid to the study of the laboratory environment if replication and translation are to be improved.

Perioperative catabolism

PURPOSE

This article reviews the pathophysiology, clinical relevance, and therapy of the catabolic response to surgical stress.

PRINCIPLE FINDINGS

The key clinical features of perioperative catabolism are hyperglycemia and loss of body protein, both metabolic consequences of impaired insulin function. Muscle weakness and (even moderate) increases in perioperative blood glucose are associated with morbidity after major surgery. Although the optimal glucose concentration for improving clinical outcomes is unknown, most medical associations recommend treatment of random blood glucose > 10 mmol·L(-1). Neuraxial anesthesia blunts the neuroendocrine stress response and enhances the anabolic effects of nutrition. There is evidence to suggest that the avoidance of preoperative fasting prevents insulin resistance and accelerates recovery after major abdominal surgery.

CONCLUSIONS

Current anticatabolic therapeutic strategies include glycemic control and perioperative nutrition in combination with optimal pain control and the avoidance of preoperative starvation. All these elements are part of Enhanced Recovery After Surgery (ERAS) programs.

Glycemia-dependent nuclear factor κB activation contributes to mechanical allodynia in rats with chronic postischemia pain

BACKGROUND

Ischemia-reperfusion injury causes chronic postischemia pain (CPIP), and rats with higher glycemia during ischemia-reperfusion injury exhibit increased allodynia. Glycemia-induced elevation of nuclear factor κB (NFκB) may contribute to increased allodynia.

METHODS

Glycemia during a 3-h ischemia-reperfusion injury was manipulated by: normal feeding; or normal feeding with administration of insulin; dextrose; or insulin/dextrose. In these groups, NFκB was measured in ipsilateral hind paw muscle and spinal dorsal horn by enzyme-linked immunosorbent assay (ELISA), and SN50, an NFκB inhibitor, was administered to determine its differential antiallodynic effects depending on glycemia.

RESULTS

CPIP fed/insulin rats (12.03 ± 4.9 g, N = 6) had less allodynia than fed, fed/insulin/dextrose, and fed/dextrose rats (6.29 ± 3.37 g, N = 7; 4.57 ± 3.03 g, N = 6; 2.95 ± 1.10 g, N = 9), respectively. Compared with fed rats (0.209 ± 0.022 AU, N = 7), NFκB in ipsilateral plantar muscles was significantly lower for fed/insulin rats, and significantly higher for fed/dextrose rats (0.152 ± 0.053 AU, N = 6; 0.240 ± 0.057 AU, N = 7, respectively). Furthermore, NFκB in the dorsal horn of fed, fed/insulin/dextrose, and fed/dextrose rats (0.293 ± 0.049 AU; 0.267 ± 0.037 AU; 0.315 ± 0.015 AU, respectively, N = 6 for each) was significantly higher than in fed/insulin animals (0.267 ± 0.037 AU, N = 6). The antiallodynic SN50 dose-response curves of CPIP rats in the fed/insulin/dextrose, fed/dextrose, and fed conditions exhibited a rightward shift compared with the fed/insulin group. The threshold SN50 dose of CPIP fed/dextrose, fed/insulin/dextrose, and fed rats (328.94 ± 92.4 ng, 77.80 ± 44.50 ng, and 24.89 ± 17.20 ng, respectively) was higher than that for fed/insulin rats (4.06 ± 7.04 ng).

CONCLUSIONS

NFκB was activated in a glycemia-dependent manner in CPIP rats. Hypoglycemic rats were more sensitive to SN50 than rats with higher glycemia. The finding that SN50 reduces mechanical allodynia suggests that NFκB inhibitors might be useful for treating postischemia pain.