Intraoperative Dexmedetomidine enhances recovery of GI function after Abdominal Surgery : JAMA

Dexmedetomidine is a highly selective α2-adrenergic receptor agonist with sedative, analgesic, sympatholytic, and anxiolytic properties. It is widely used as an anesthetic adjuvant in perioperative settings and as a sedative in the intensive care unit.

A prospective study was conducted to investigate the effect of low-dose intraoperative dexmedetomidine on the recovery of gastrointestinal function after abdominal surgery among older patients. Yao Lu et al hypothesized that intraoperative administration of low-dose dexmedetomidine would accelerate the recovery of gastrointestinal function after surgery.

This multicenter, double-blind, placebo-controlled randomized clinical trial was conducted at the First Affiliated Hospital of Anhui Medical University in Hefei, China (lead site), and 12 other tertiary hospitals in Anhui Province, China. A total of 808 participants aged 60 years or older who were scheduled to receive abdominal surgery with an expected surgical duration of 1 to 6 hours were enrolled. The study was conducted from August 21, 2018, to December 9, 2019. Dexmedetomidine infusion (a loading dose of 0.5 μg/kg over 15 minutes followed by a maintenance dose of 0.2 μg/kg per hour) or placebo infusion (normal saline) during surgery was given as intervention.

The primary outcome was time to first flatus. Secondary outcomes were postoperative gastrointestinal function measured by the I-FEED (intake, feeling nauseated, emesis, physical examination, and duration of symptoms) scoring system, time to first feces, time to first oral feeding, incidence of delirium, pain scores, sleep quality, postoperative nausea and vomiting, hospital costs, and hospital length of stay.

• Among 808 patients enrolled, 404 were randomized to receive intraoperative dexmedetomidine, and 404 were randomized to receive placebo.

• The dexmedetomidine group had a significantly shorter time to first flatus (median, 65 hours vs 78 hours espectively; P < .001), time to first feces (median, 85 hours vs 98 hours; P = .001), and hospital length of stay (median, 13 days vs 15 days; P = .005) than the control group.

• Postoperative gastrointestinal function (as measured by the I-FEED score) and delirium incidence were similar in the dexmedetomidine and control groups.

The study's findings demonstrated that dexmedetomidine decreased the time to first flatus and feces compared with saline placebo but did not find any statistically significant difference in postoperative gastrointestinal function as measured by the I-FEED score. Notably, the use of intraoperative dexmedetomidine had no effect on the incidence of delirium in the first 3 postoperative days. However, opioid medication use, pain scores, hospitalization costs, and hospital length of stay were significantly lower in the dexmedetomidine group compared with the control group.

The intraoperative administration of low-dose dexmedetomidine in patients undergoing open and laparoscopic abdominal surgeries did reduce the time to first flatus, suggesting the dose and context of administration are relevant in determining the benefits of dexmedetomidine associated with return of gastrointestinal function.

The pathophysiological mechanism of postoperative ileus involves complex processes in which inflammation, ischemic reperfusion injury, fluid administration, and pharmacological factors interact. Opioid medications have been associated with impairment of gastrointestinal motility through a dose-dependent inhibitory effect. The κ, μ, and δ opioid receptor subtypes have been identified on neurons of submucosal and myenteric plexuses. Therefore, the decreased use of sufentanil and remifentanil medications after the receipt of intraoperative dexmedetomidine, which was observed in the present study, may have beneficial effects on the postoperative recovery of gastrointestinal function. Furthermore, dexmedetomidine has the ability to attenuate ischemic reperfusion injury, inhibit inflammatory response, and improve stress response and these benefits may also provide plausible explanations for the reduced time to gastrointestinal recovery.

"Among older patients undergoing abdominal surgery, intraoperative dexmedetomidine significantly reduced the time to first flatus, time to first feces, and hospital length of stay without affecting the I-FEED score. Consideration of the use of intraoperative dexmedetomidine as part of the overall strategy for enhanced recovery after abdominal surgery is warranted"

Source: doi:10.1001/jamanetworkopen.2021.28886