Cognitive clarity in colon surgery: The dexmedetomidine advantage

Abstract

Colon cancer is one of the most prevalent cancers globally, especially in the older age group. A large number of older patients undergoing surgery for colon cancer suffer from postoperative cognitive dysfunction (POCD). The trial by Bu et al demonstrated that dexmedetomidine (Dex) significantly reduced the incidence of POCD compared to placebo in individuals undergoing colon cancer surgery. Additionally, better cerebral oxygenation and lower cerebral injury markers were reported with the use of Dex. The trial has some limitations, such as a single-center design and a smaller sample size, and further studies with larger patient populations and robust multi-center designs are warranted to establish these findings.

Key Words: Dexmedetomidine; Colon cancer; Old age group; Postoperative cognitive dysfunction; Cerebral injury

Core Tip: This letter highlights the trial by Bu et al, which reveals that dexmedetomidine can significantly reduce the incidence of postoperative cognitive dysfunction and improve cerebral oxygenation in elderly patients undergoing radical colon cancer surgery. Despite several limitations, the study reflects profound clinical implications while suggesting additional research and innovative approaches to treatment.

TO THE EDITOR

Colon cancer is the third most fatal and second most prevalent cancer worldwide, with over 1.1 million new cases and nearly 1 million deaths in 2020 alone[1]. Particularly in the older population, after the age of 50 years, the incidence and mortality due to colon cancer have risen dramatically by 40%[2]. With a complex pathophysiology starting from the formation of polyps and ultimately leading to malignancy, this cancer requires prompt interventions. As the patient population continues to rise, the number of elderly patients requiring surgical interventions, such as radical colon cancer surgery, increases significantly. However, postoperative cognitive dysfunction (POCD), which can severely affect recovery and quality of life, is a major concern in this age group.

Dexmedetomidine (Dex) is a highly selective α2-adrenoceptor agonist with sedative, analgesic-sparing, anxiolytic, and sympatholytic effects[3]. It blocks norepinephrine release, which lowers the excitability of the sympathetic nervous system. This inhibitory action lowers blood pressure and heart rate variations, and aids in maintaining hemodynamic stability during surgery[4]. These qualities of Dex, combined with its anesthetic characteristics, can offer promising results in reducing POCD and other postoperative complications in elderly patients undergoing surgery for colon cancer. However, there is a paucity of thorough data specifically pertaining to older individuals undergoing significant colon cancer surgeries. In this critical context, Bu et al[5] conducted a clinical trial to explore the efficacy and safety of Dex in older patients undergoing colon cancer surgery.

DEX AND POST-OPERATIVE COMPLICATIONS

Bu et al[5] conducted a randomized clinical trial to evaluate the efficacy of Dex in elderly patients who were scheduled for elective colon cancer surgery. The trial included 117 patients, aged between 65 and 79 years, divided into two groups: Group A (n = 59) was given Dex, while group B (n = 58) was given normal saline as a placebo[5]. To ensure that the results could be directly attributed to the intervention, the study methodically controlled for factors including the length of the procedure and the dosage of anesthetics. Cerebral oxygen saturation (rSO2), anesthetic drug dosages, cognitive function assessments, and serum levels of biomarkers S100β and neuron-specific enolase (NSE) were the main parameters assessed. These biomarkers are important indications of both cognitive decline and neuronal damage.

Bu et al[5] reported that, compared to the placebo group, the Dex group required a substantially smaller overall dosage of anesthetic drugs. This reduction in anesthetic drug usage is specifically beneficial for elderly patients, who are more vulnerable to drug-related adverse effects and complications. Additionally, patients in the Dex group exhibited higher rSO2, a higher glucose uptake rate, and a lower lactate production rate, indicating better rSO2 and more efficient brain metabolism. Furthermore, serum levels of S100β and NSE were lower in the Dex group, correlating with reduced neuronal injury. Most importantly, the incidence of POCD and adverse reactions was significantly lower in the Dex group, suggesting enhanced cognitive function and overall well-being[5]. These findings are in line with a meta-analysis by Yu et al[6], which indicated that Dex significantly reduced the incidence of POCD in elderly patients receiving surgeries (risk ratio: 0.47; P < 0.001).

Strengths and limitations

The innovative efforts by Bu et al[5] to evaluate the efficacy and safety of Dex in this age group are to be appreciated. The study used a randomized clinical trial design, the most reliable method for assessing the effectiveness of an intervention. With a specific focus on older patients and clearly defining the patient population, the trial addressed an essential clinical hurdle and offered relevant insights for this susceptible age group. Moreover, evaluating numerous outcomes provides an in-depth view of the intervention’s implications from both clinical and biochemical aspects. In addition, the continued control of anesthesia during the procedures and the employment of the same surgical team for all the cases ensured the consistency and validity of the results.

However, this study has multiple shortcomings and limitations that should be considered. Firstly, the trial was conducted at a single center, which may limit the generalizability of the reported results. Secondly, the primary focus of the study is on short-term outcomes, specifically POCD during the initial postoperative phase. Understanding the entire effect of the intervention requires addressing long-term cognitive results and other possible late effects of Dex. Thirdly, although the study assessed biochemical indicators and cognitive function, it ignored functional outcomes that are important for assessing the intervention’s real-world impact. These outcomes include activities of daily living, quality of life, and long-term neurological status.

Clinical implications

The findings in the clinical trial by Bu et al[5] carry some profound clinical implications. According to the results, Dex lowers neuronal damage indicators and increases cerebral oxygenation. These neuroprotective properties can be used by clinicians to safeguard cognitive function in older patients both during and after surgery. In this high-risk group, the decreased incidence of POCD with Dex can enhance long-term cognitive health and quality of life. Notably, using Dex in anesthesia protocols may reduce drug-related adverse effects and complications, as seen by the lower overall dosage of anesthetic drugs needed during colon surgery in the Dex group. Furthermore, the capacity of Dex to maintain hemodynamic stability throughout surgery is especially beneficial for older patients and can contribute to more stable future perioperative care.

CONCLUSION

The trial by Bu et al presented strong evidence for using Dex in elderly patients undergoing colon cancer surgery[5]. The results show that Dex can improve cerebral oxygenation, dramatically reduce the need for anesthetic drugs, and lessen the risk of adverse reactions and POCD. Larger, multicenter trials that can yield more reliable and generalized data are needed in the future to validate and strengthen these findings. However, current findings can affect immediate clinical practices, even as larger studies are awaited. To completely comprehend the effects of Dex, further research is required to evaluate the long-term cognitive and functional outcomes of older patients with colon cancer.