Impact of dexmedetomidine-assisted anesthesia in elderly patients undergoing radical resection of colon cancer

Abstract

BACKGROUND

Radical resection of colon cancer under general anesthesia is one of the main treatment methods for this malignancy. However, due to the physiological characteristics of elderly patients, the safety of perioperative anesthesia needs special attention. As an α2-adrenergic receptor agonist, dexmedetomidine (Dex) has attracted much attention from anesthesiologists due to its stabilizing effect on heart rate and blood pressure, inhibitory effect on inflammation, and sedative and analgesic effects. Its application in general anesthesia may have a positive impact on the quality of anesthesia and postoperative recovery in elderly patients undergoing radical resection of colon cancer.

AIM

To investigate the anesthetic effects of Dex during radical surgery for colon cancer under general anesthesia in elderly patients.

METHODS

A total of 165 colon cancer patients who underwent radical surgery for colon cancer under general anesthesia at Qingdao University Affiliated Haici Hospital, Qingdao, China were recruited and divided into two groups: A and B. In group A, Dex was administered 30 min before surgery, while group B received an equivalent amount of normal saline. The hemodynamic changes, pulmonary compliance, airway pressure, inflammatory factors, confusion assessment method scores, Ramsay Sedation-Agitation Scale scores, and cellular immune function indicators were compared between the two groups.

RESULTS

Group A showed less intraoperative hemodynamic fluctuations, better pulmonary compliance, and lower airway resistance compared with group B. Twelve hours after the surgery, the serum levels of TLR-2, TLR-4, IL-6, and TNF-α in group A were significantly lower than those of group B (P < 0.05). After extubation, the Ramsay Sedation-Agitation Scale score of group A patients was significantly higher than that of group B patients, indicating a higher level of sedation. The incidence of delirium was significantly lower in group A than in group B (P < 0.05).

CONCLUSION

The use of Dex as an adjunct to general anesthesia for radical surgery in elderly patients with colon cancer results in better effectiveness of anesthesia.

Key Words: Dexmedetomidine; General anesthesia; Elderly; Colon cancer radical surgery; Anesthesia effectiveness; Delirium; Cellular immunity

Core Tip: This study investigated the anesthetic effects of dexmedetomidine (Dex) during radical surgery in elderly patients with colon cancer under general anesthesia. The use of Dex as an adjunct to general anesthesia for radical surgery in elderly patients with colon cancer resulted in better effectiveness of anesthesia, less intraoperative hemodynamic fluctuations, reduced inflammatory response caused by surgery, better pulmonary compliance, lower airway resistance, and decreased incidence of anesthesia-induced delirium.

INTRODUCTION

Colorectal cancer (CRC) ranks among the most prevalent malignancies in the elderly population. Radical surgery for colon cancer under general anesthesia is one of the primary treatment modalities for this malignancy. However, due to the physiological characteristics of elderly patients, they are prone to various complications, such as hemodynamic instability, inadequate oxygenation, and delirium, during and after surgery. These factors affect the effectiveness of surgery and patients' recovery[1-3]. Therefore, exploring more effective anesthetic methods to enhance surgical safety and improve postoperative recovery is crucial for elderly patients with CRC. Dexmedetomidine (Dex) is an α2-adrenergic receptor agonist that has gained significant attention due to its stabilizing effects on heart rate (HR) and blood pressure, inhibitory effects on inflammatory responses, and sedative and analgesic properties[4]. Its use under general anesthesia may have a positive impact on the quality of intraoperative anesthesia and postoperative recovery in elderly patients with colon cancer[5,6]. Therefore, this study aimed to analyze the anesthetic effects of Dex in conjunction with general anesthesia during radical surgery for colon cancer in elderly patients. Specific aspects of the analysis included physiological indicators, such as arterial pressure, HR, oxygen saturation, pulmonary compliance, and airway pressure, as well as peripheral blood markers of immune inflammation and postoperative recovery. The findings of this study will provide effective scientific guidance for anesthesia management in elderly patients with colon cancer, ultimately improving their surgical outcomes and quality of life.

MATERIALS AND METHODS

Patients

In this randomized clinical trial, 165 colon cancer patients who were scheduled to undergo elective radical surgery between January 2021 and June 2023 at Qingdao University Affiliated Haici Hospital, Qingdao, China were included. The patients were divided into two groups using a random number table: A (83 patients) and B (82 patients). Demographic data, including age and sex, were comparable between the two groups (P > 0.05; Table 1).

Table 1 Comparison of basic data between the two groups of patients.

Group	n	Age (year)	BMI(kg/m2)	Gender, n (%)		Years of education	ASA grade, n (%)		Hypertension, n (%)	Diabetes, n (%)
				Male	Female		Grade I	Grade II
A	83	63.8 ± 8.1	22.74 ± 1.86	46 (55.42)	37 (44.58)	5.41 ± 1.60	30 (36.14)	53 (63.86)	29 (34.94)	13 (15.66)
B	82	61.5 ± 7.7	23.10 ± 2.00	40 (48.78)	42 (51.22)	5.10 ± 1.73	39 (47.56)	43 (52.44)	34 (41.46)	18 (21.95)
t/χ2 value		1.869	-1.197	0.729		1.195	2.210		0.744	1.069
P value		0.063	0.233	0.393		0.234	0.137		0.388	0.301

ASA: American Society of Anesthesiologists.

The inclusion criteria were: (1) The diagnostic criteria for patients with colon cancer included in this study were based on the Chinese Society of Clinical Oncology Colorectal Cancer Diagnosis and Treatment Guidelines 2020 Edition[7]; (2) The age of the patients ranged from 45 to 79 years; (3) All patients underwent colonoscopy before surgery, and tissue specimens were obtained for pathological examination to confirm the diagnosis; (4) The patients had an American Society of Anesthesiologists[8] grade of I or II; and (5) All the patients underwent elective surgeries performed by the same medical staff.

The exclusion criteria were: (1) Metastatic CRC; (2) Intestinal obstruction, perforation, and abdominal infection; (3) Immune diseases; (4) Human immunodeficiency virus infection; (5) Abnormal coagulation function; (6) History of epilepsy or senile dementia; and (7) Atrial fibrillation and arrhythmias.

This study was conducted according to the Declaration of Helsinki. Written informed consent was obtained from all patients before surgery. The study protocol was approved by the local Medical Ethics Committee.

Anesthesia and surgical methods

Patients in group A received a continuous infusion of Dex at a rate of 0.4 μg/kg/h for 30 min before surgery, while patients in group B were only administered an equivalent amount of normal saline. In both groups, the infusion was stopped at the time of skin closure during surgery.

Both groups used the same anesthesia induction and maintenance protocols. Patients were required to fast for 8 h and abstain from drinking for 4 h before surgery, and they did not receive any medication prior to anesthesia induction. Two intravenous lines were established for each patient, and continuous monitoring of HR, blood pressure, electrocardiogram, and SpO₂ was conducted throughout the surgery. In addition, arterial pressure was monitored in real time through radial artery cannulation under local anesthesia. Both groups of patients received intravenous inhalation of combined anesthetics. During the anesthesia induction phase, the following medications were used: Citric acid sufentanil (Yichang Renfu Pharmaceutical Co., Ltd., National Drug Approval Number H20054256) at a dose of 0.2-0.3 μg/kg; etomidate (Jiangsu Hengrui Medicine Co., Ltd., National Drug Approval Number H32022379) at a dose of 0.2 mg/kg; cisatracurium [Dongying (Jiangsu) Pharmaceutical Co., Ltd., National Drug Approval Number H20060926] at a dose of 0.2 mg/kg. Respiratory parameters were controlled using a Draeger Primus anesthesia machine (Germany). The tidal volume was set at 6-8 mL/kg, ensuring that the end-tidal carbon dioxide partial pressure was maintained between 30-45 mmHg, and the respiratory rate was maintained at 12 breaths/min. For anesthesia maintenance, sevoflurane (produced, Shanghai Hengrui Medicine Co., Ltd., H20070172) was administered via inhalation, and a continuous intravenous infusion of remifentanil hydrochloride (Jiangsu Enhua Pharmaceutical Co., Ltd., National Drug Approval Number H20143314) was maintained at a dose of 0.5 to 1 μg/kg/min. Simultaneously, the end-tidal concentration of the inhaled anesthetic was maintained within the range of 1.0-1.3 minimum alveolar concentration. Additional intermittent doses of cisatracurium and sufentanil were administered during surgery. In the last 30 min before the end of the surgery, intravenous administration of ondansetron (produced by Qilu Pharmaceutical Co., Ltd., National Drug Approval Number H10970065) at a dose of 4 mg and sufentanil at a dose of 1 μg/kg was given, while the inhalation of sevoflurane and the infusion of remifentanil were stopped. The flow rate was set to 8 L/min with oxygen concentration adjusted to 100%. Once the patient was fully awake, the endotracheal tube was removed and the patient was transferred to the post-anesthesia recovery room.

Observation indicators and evaluation methods

Continuous monitoring was conducted to observe dynamic changes in mean arterial pressure (MAP), HR, SpO₂, pulmonary compliance, and airway pressure. Additionally, a comparison was made between the two groups of patients regarding the following peripheral blood parameters: TLR-2 and TLR-4, IL-6, TNF-α, confusion assessment method (CAM) scores for delirium assessment, Ramsay Sedation-Agitation Scale scores for sedation assessment during the awakening period, and cellular immune function indicators (CD3⁺, CD4⁺, CD8⁺, and CD3^-CD16⁺CD56⁺ cells).

The CAM primarily consists of four aspects for evaluating delirium: Alterations or fluctuations in a patient's consciousness, lack of concentration, disorganized thinking, and changes in the level of consciousness. Delirium was diagnosed if a patient met any of these criteria.

The Ramsay Sedation-Agitation Scale[9] has a score that ranges from 1 to 6 points: 1 point, restlessness; 2 points, the patient is awake and alert; 3 points, the patient is in a drowsy state but responds promptly to commands from doctors and nurses; 4 points, the patient is in a light sleep state and could be easily awakened; 5 points, the patient is in a deep-sleep state and responds sluggishly to calls from doctors and nurses; and 6 points, the patient is in a state of very deep sleep and does not respond to calls from doctors or nurses.

Venous blood (6-10) was collected in two separate tubes from each patient. One blood sample was processed by EDTA anticoagulation, diluted, centrifuged, and washed to collect the cells, which were then prepared into peripheral blood mononuclear cell (PBMC) suspensions. Subsequently, the density of PBMCs was adjusted to 10000 cells/mL, and immunological parameters were analyzed using a FACSCalibur flow cytometer (BD, United States). The immunological parameters measured included the levels of T lymphocyte subsets (CD3⁺, CD4⁺, and CD8⁺) and NK cells (CD3^-CD16⁺ CD56⁺).

The blood samples that were left were subjected to centrifugation at 3000 rpm for a 15 min (with a centrifugal radius of 10 cm) to separate the serum. ELISA was then used to detect the levels of TLR-2, TLR-4, IL-6, and TNF-α in the serum.

Statistical analysis

Data were analyzed using SPSS21.0. The measurement data of TLR-2, TLR-4, IL-6, TNF-α, MAP, HR, and SpO₂ collected in this study are described as the mean ± SD. A t-test was used for comparative analysis between the two groups. Enumeration data are described as rates (%), and the data were compared by the χ² test.

RESULTS

Comparison of operation parameters and anesthetic dosage between the two groups

Surgical duration, duration of anesthesia, intraoperative blood loss, intraoperative fluid replacement volume, and propofol dosage were comparable between the two groups of patients (P > 0.05). Group A received a lower dose of remifentanil than group B (P < 0.05; Table 2).

Table 2 Comparison of operation parameters and anesthetic dosage between the two groups of patients, mean ± SD.

Group	n	Surgical duration (min)	Anesthesia duration (min)	Intraoperative blood loss (mL)	Intraoperative fluid replacement volume (mL)	Propofol dosage (mg)	Remifentanil dosage (mg)
A	83	168.9 ± 17.5	188.5 ± 22.0	244.3 ± 28.0	934.1 ± 176.5	1759.4 ± 166.0	1.24 ± 0.21
B	82	172.5 ± 19.2	193.0 ± 24.1	250.0 ± 33.8	951.0 ± 184.0	1810.6 ± 178.2	1.35 ± 0.23
t value		-1.259	-1.253	-1.180	-0.602	-1.910	-3.209
P value		0.210	0.212	0.240	0.548	0.058	0.002

Comparison of fluctuations of MAP, HR, and SpO₂ in the two groups

Before anesthesia induction, the MAP, HR, and SpO₂ values of the two groups were comparable (P > 0.05). However, after intubation, the MAP in group A was significantly higher than that of group B group at 5 and 30 min, and the HR of group A was significantly higher than that of group B at 30 min during surgery (P < 0.05). The SpO₂ values at different time points before anesthesia induction, 5 min after intubation, during surgery, and postoperatively were comparable between the two groups (P > 0.05; Table 3 and Figure 1).

Figure 1 Fluctuation and variation trends of mean arterial pressure, heart rate, and SpO₂ in the two groups of patients. A: Mean arterial pressure; B: Heart rate; C: SpO₂. MAP: Mean arterial pressure; HR: Heart rate; Dex: Dexmedetomidine. ^aP < 0.05.

Table 3 Comparison of fluctuations of mean arterial pressure, heart rate, and SpO₂ in the two groups, mean ± SD.

Index	Group	Before anesthesia induction	5 min after intubation	Intraoperative 30 min	During extubation	3 min after extubation
MAP (mmHg)	A (n = 83)	101.8 ± 5.4	89.6 ± 4.1	87.0 ± 5.0	105.8 ± 5.4	100.6 ± 6.2
	B (n = 82)	103.0 ± 5.8	86.2 ± 5.3	83.1 ± 4.9	107.0 ± 6.7	102.3 ± 6.8
	t value	-1.376	4.612	5.060	-1.267	-1.678
	P value	0.171	0.000	0.000	0.207	0.095
HR (beats/min)	A (n = 83)	78.9 ± 5.4	73.0 ± 5.8	71.7 ± 5.5	83.2 ± 6.2	80.0 ± 6.1
	B (n = 82)	77.4 ± 6.0	71.4 ± 6.2	69.6 ± 6.3	84.4 ± 6.7	81.7 ± 6.8
	t value	1.688	1.712	2.282	-1.194	-1.691
	P value	0.093	0.089	0.024	0.234	0.093
SpO2 (%)	A (n = 83)	98.64 ± 0.77	95.40 ± 0.60	95.72 ± 0.58	96.81 ± 0.80	97.48 ± 0.77
	B (n = 82)	98.80 ± 0.81	95.26 ± 0.57	95.54 ± 0.60	96.64 ± 0.75	97.31 ± 0.69
	t value	-1.301	1.536	1.959	1.408	1.493
	P value	0.195	0.126	0.052	0.161	0.137

MAP: Mean arterial pressure; HR: Heart rate.

Comparison of lung compliance indexes between the two groups

Before anesthesia induction, lung compliance and airway peak pressure of the two groups were comparable (P > 0.05). Lung compliance was significantly higher and the peak airway pressure was significantly lower in group A than in group B at 5 min after intubation, 30 min during surgery, during extubation, and 3 min after extubation (P < 0.05; Table 4 and Figure 2).

Figure 2 Fluctuation and variation trends of pulmonary compliance and airway peak pressure measurement values in the two groups of patients. A: Lung compliance; B: Peak airway pressure. Dex: Dexmedetomidine. ^aP < 0.05.

Table 4 Comparison of lung compliance indexes between the two groups of patients, mean ± SD.

Index	Group	Before anesthesia induction	5 min after intubation	Intraoperative 30 min	During extubation	3 min after extubation
Lung compliance (mL/cmH2O)	A (n = 83)	46.61 ± 3.71	38.60 ± 3.20	39.19 ± 2.98	41.02 ± 3.20	44.67 ± 2.77
	B (n = 82)	47.03 ± 3.90	36.46 ± 3.43	36.74 ± 3.31	39.36 ± 3.43	42.70 ± 3.28
	t value	-0.709	4.144	4.998	3.215	4.170
	P value	0.479	0.000	0.000	0.002	0.000
Peak inflation pressure (cmH2O)	A (n = 83)	11.30 ± 1.63	13.35 ± 1.80	13.40 ± 1.75	13.11 ± 1.64	12.37 ± 1.58
	B (n = 82)	11.01 ± 1.51	14.40 ± 1.68	14.82 ± 1.89	13.54 ± 1.72	12.78 ± 1.70
	t value	1.185	-3.873	-5.008	-1.644	-1.605
	P value	0.238	0.000	0.000	0.102	0.110

Comparison of inflammatory factor levels between the two groups

Before surgery, the serum levels of TLR-2, TLR-4, IL-6, and TNF-α were comparable between the two groups (P > 0.05). Twelve hours postoperatively, the serum levels of TLR-2, TLR-4, IL-6, and TNF-α in group A were significantly lower than those of group (P < 0.05; Table 5), suggesting that group A group exhibited milder inflammatory responses.

Table 5 Comparison of inflammatory factor levels between the two groups of patients, mean ± SD.

Group	n	TLR-2 (ng/mL)		TLR-4 (ng/mL)		IL-6 (pg/mL)		TNF-α (pg/mL)
		Before surgery	1 h after surgery	Before surgery	1 h after surgery	Before surgery	1 h after surgery	Before surgery	1 h after surgery
A	83	0.41 ± 0.10	1.28 ± 0.36	1.04 ± 0.39	2.54 ± 0.68	4.41 ± 1.20	10.71 ± 2.54	13.20 ± 4.10	34.28 ± 6.95
B	82	0.43 ± 0.12	1.71 ± 0.48	1.12 ± 0.43	3.30 ± 0.91	4.80 ± 1.43	11.63 ± 2.86	14.41 ± 4.76	40.68 ± 7.73
t value		-1.164	-6.515	-1.252	-6.082	-1.899	-2.185	-1.750	-5.594
P value		0.246	0.000	0.212	0.000	0.059	0.030	0.082	0.000

Comparison of cellular immune indexes between the two groups

Before surgery, CD3⁺, CD4⁺, CD8⁺, and CD3-CD16⁺ CD56⁺ cell percentages were comparable between the two groups before surgery and at 12 h postoperatively (P > 0.05), suggesting that the effect on cellular immunity did not differ significantly between the two groups (Table 6).

Table 6 Comparison of cellular immune indexes between the two groups of patients, mean ± SD.

Group	n	CD3+ (%)		CD4+ (%)		CD8+ (%)		CD3-CD16+ CD56 + (%)
		Before surgery	12 h after surgery	Before surgery	12 h after surgery	Before surgery	12 h after surgery	Before surgery	12 h after surgery
A	83	63.8 ± 6.2	56.1 ± 4.8	40.3 ± 4.0	36.8 ± 3.9	22.3 ± 2.9	25.7 ± 3.4	14.7 ± 2.0	10.6 ± 2.6
B	82	65.0 ± 6.5	55.3 ± 5.0	41.5 ± 4.4	37.4 ± 4.2	21.5 ± 3.2	26.6 ± 3.8	14.2 ± 2.2	10.1 ± 2.7
t value		-1.214	1.048	-1.833	-0.951	1.683	-1.604	1.528	1.212
P value		0.227	0.296	0.069	0.343	0.094	0.111	0.128	0.227

Comparison of sedative effect and incidence of delirium between the two groups

In the assessment of anesthesia effectiveness conducted after extubation, the Ramsay Sedation-Agitation Scale scores of patients were significantly higher in group A than in group B, while the incidence of delirium was significantly lower in group A than in group B (P < 0.05; Table 7).

Table 7 Comparison of sedative effect and incidence of delirium between the two groups of patients.

Group	n	Ramsay score (score)	Incidence of delirium (%)
A	83	3.39 ± 0.84	11 (13.25)
B	82	2.94 ± 0.70	27 (32.93)
t/χ2 value		3.736	9.007
P value		0.000	0.003

DISCUSSION

Elderly patients undergoing curative surgery for colon cancer face several significant challenges, including maintenance of intraoperative physiological stability and optimization of postoperative recovery[10,11]. This patient population often has various chronic diseases such as cardiovascular and respiratory system disorders. Under general anesthesia, the presence of these conditions can increase surgical risks[12,13]. Complications such as hemodynamic instability, respiratory function failure, and cognitive impairment (such as postoperative delirium) that occur during and after surgery can significantly affect patient recovery and long-term prognosis[14,15]. Therefore, the selection of appropriate anesthetic agents and the optimization of anesthesia management are crucial for improving surgical success rates and reducing complications. Dex, a novel α2-adrenergic receptor agonist, has been associated with better hemodynamic stability and a potential reduction in postoperative delirium than traditional anesthetic drugs[16,17]. However, the efficacy and safety of Dex in elderly patients undergoing curative surgery for colon cancer have not yet been fully investigated. This randomized clinical trial aimed to assess the use of Dex under general anesthesia in elderly patients undergoing curative surgery for colon cancer.

The results of this study showed no significant differences (P > 0.05) between the two groups in terms of surgical duration, anesthesia duration, intraoperative bleeding volume, intraoperative fluid replacement volume, and propofol dosage. This suggests that the use of Dex does not significantly affect these basic surgical and anesthetic parameters. Moreover, at 5 min after intubation and 30 min after surgery, group A exhibited a smaller decrease in MAP than group B, and the HR of patients in group A was higher than that of group B at 30 min after surgery, indicating that the application of Dex helps stabilize intraoperative hemodynamics. Our analysis showed that the use of Dex enhanced the analgesic effect and suppressed the stress responses caused by pain. Specifically, the sedative and hypnotic effects of Dex are linked to the stimulation of α2 adrenergic receptors within the locus coeruleus region of the brainstem[18,19]. The locus coeruleus is a crucial component of the central nervous system that is involved in various physiological processes, including sleep control and wakefulness[20]. Dex, by activating α2 receptors, reduced the activity of the sympathetic nervous system, thereby lowering neuronal firing rates and the release of norepinephrine and resulting in reduced fluctuations in blood pressure and HR [21,22].

The results of this study also indicated that group A required a lower dose of remifentanil than group B (P < 0.05), suggesting a reduced need for analgesics in group A. Thus, we surmise that Dex provides adjunctive analgesic effects and enhances analgesic efficacy. Additionally, in terms of lung compliance and airway peak pressure, group A showed better measurements at 5 min after intubation, 30 min after surgery, during extubation, and after extubation than group B. Moreover, the peak airway pressure in group A was significantly lower than that of group B at 5 min after intubation and 30 min after surgery (P < 0.05). This indicates that Dex is beneficial for improving lung function and reducing airway resistance. This is mainly because Dex can exert lung protection by reducing the activity of inflammatory factors such as TNF-α, alleviating lung damage associated with mechanical ventilation, and reducing the inflammatory response triggered by endothelin, which is consistent with the research of Gao et al[23]. At the same time, further comparison of inflammatory indicators showed that 12 h after surgery, the serum levels of TLR-2, TLR-4, IL-6, and TNF-α in the Dex group were significantly lower than those of the control group (P < 0.05), indicating that Dex, to some extent, inhibited the postoperative inflammatory response. This is mainly attributed to the analgesic effect of Dex, which can inhibit the stress response and inflammatory cytokine release caused by pain. The exact mechanism is that Dex can activate the cholinergic transporter α7 nicotinic acetylcholine receptor, activate the vagus nerve, and thereby reduce the production of the inflammatory cytokines IL-6 and TNF-α. At the same time, the TLR4/MyD88/ERK1/2/NF-κB signaling pathway is inhibited, leading to a decrease in the release of inflammatory mediators (TLR-2 and TLR-4), which further confirms the Dex's protective effect on the lungs[24-26].

This study also compared the cellular immune function of patients, and the results showed that there was no significant difference in the levels of CD3⁺, CD4⁺, CD8⁺, CD3^-CD16⁺CD56⁺ cell percentages between the Dex group and the control group before and 12 h after surgery (P > 0.05). However, the Ramsay Sedation-Agitation Scale score of the Dex group was significantly higher than that of the control group, and the incidence of delirium was significantly lower than that of the control group (P < 0.05), indicating that the sedative effect in the Dex group was better and safer. Opioid drugs can activate opioid receptors in the brain, affecting the balance of various neurotransmitters such as dopamine, serotonin, and norepinephrine. This imbalance can lead to cognitive dysfunction and delirium. Dex, while exerting sedative effects, can also reduce the dosage of the opioid remifentanil by exerting analgesic effects, thereby enhancing sedative effects while reducing the impact of remifentanil on patient cognitive function. The analgesic effect of Dex is achieved through various mechanisms at different levels of the nervous system. First, at the peripheral nerve level, it inhibits the activity of Aδ and C class afferent nerve fibers, triggering cell hyperpolarization and thus blocking the peripheral transmission of pain signals[27,28]. Second, at the level of the locus coeruleus in the brainstem, it reduces the release of substance P from nerve endings and prevents the transmission of pain information in the dorsal horn of the spinal cord. Finally, at the spinal cord level, Dex synergistically inhibits the release of norepinephrine and enhances the activity of cholinergic nerves by binding to alpha 2A receptors, collectively reducing the perception of nociceptive stimuli[29,30].

CONCLUSION

The use of Dex as an adjunct to general anesthesia for radical surgery in elderly patients with colon cancer results in better effectiveness of anesthesia, less intraoperative hemodynamic fluctuations, reduced inflammatory response caused by surgery, better pulmonary compliance, lower airway resistance, and decreased incidence of anesthesia-induced delirium.