Effect of sedation with dexmedetomidine or propofol on gastrointestinal motility in lipopolysaccharide-induced endotoxemic mice

Magnetic Resonance Imaging of Gastric Motility in Conscious Rats

Introduction

Gastrointestinal (GI) magnetic resonance imaging (MRI) can simultaneously capture gastric peristalsis, emptying, and intestinal filling and transit. Performing GI MRI with animals requires anesthesia, which complicates physiology and confounds interpretation and translation from animals to humans. This study aims to enable MRI in conscious rats, and for the first time, characterize GI motor functions in awake versus anesthetized conditions.

Methods

We acclimated rats to remain awake, still, and minimally stressed during MRI. We scanned 14 Sprague-Dawley rats in both awake and anesthetized conditions after voluntarily consuming a contrast-enhanced test meal.

Results

Awake rats remained physiologically stable during MRI, showed gastric emptying of 23.7±1.4% after 48 minutes, and exhibited strong peristaltic contractions propagating through the antrum with a velocity of 0.72±0.04 mm/s, a relative amplitude of 40.7±2.3%, and a frequency of 5.1±0.1 cycles per minute. In the anesthetized condition, gastric emptying was about half of that in the awake condition, likely due to the effect of anesthesia in halving the amplitudes of peristaltic contractions rather than their frequency (not significantly changed) or velocity. In awake rats, the intestine filled more quickly and propulsive contractions were more occlusive.

Conclusion

We demonstrated the effective acquisition and analysis of GI MRI in awake rats. Awake rats show faster gastric emptying, stronger gastric contraction with a faster propagation speed, and more effective intestinal filling and transit, compared to anesthetized rats. Our protocol is expected to benefit future preclinical studies of GI physiology and pathophysiology.

Effects of remimazolam tosilate on gastrointestinal hormones and gastrointestinal motility in patients undergoing gastrointestinal endoscopy with sedation: a randomized control trial

PURPOSE

To investigate the impacts of remimazolam tosilate on gastrointestinal hormones and motility in patients undergoing gastrointestinal endoscopy with sedation.

METHODS

A total of 262 American Society of Anesthesiologists Physical Status I or II patients, aged 18-65 years, scheduled for gastrointestinal endoscopy with sedation, were randomly allocated into two groups (n = 131 each): the remimazolam tosilate group (Group R) and the propofol group (Group P). Patients in Group R received 0.2-0.25 mg/Kg remimazolam tosilate intravenously, while those in Group P received 1.5-2.0 mg/kg propofol intravenously. The gastrointestinal endoscopy was performed when the Modified Observer's Assessment of Alertness/Sedation scores were ≤3. The primary endpoints included the endoscopic intestinal peristalsis rating by the endoscopist; serum motilin and gastrin levels at fasting without gastrointestinal preparation (T0), before gastrointestinal endoscopy (T1), and before leaving the Post Anesthesia Care Unit (T2); and the incidences of abdominal distension during Post Anesthesia Care Unit.

RESULTS

Compared with Group P, intestinal peristalsis rating was higher in Group R (P < .001); Group R showed increased motilin and gastrin levels at T2 compared with Group P (P < .01). There was a rise in motilin and gastrin levels at T1 and T2 compared with T0 and at T2 compared with T1 in both groups (P < .01). The incidence of abdominal distension was lower in Group R (P < .05).

CONCLUSION

Compared with propofol used during gastrointestinal endoscopy with sedation, remimazolam tosilate mildly inhibits the serum motilin and gastrin levels, potentially facilitating the recovery of gastrointestinal motility.

An ingestible self-propelling device for intestinal reanimation

Postoperative ileus (POI) is the leading cause of prolonged hospital stay after abdominal surgery and is characterized by a functional paralysis of the digestive tract, leading to symptoms such as constipation, vomiting, and functional obstruction. Current treatments are mainly supportive and inefficacious and yield acute side effects. Although electrical stimulation studies have demonstrated encouraging pacing and entraining of the intestinal slow waves, no devices exist today to enable targeted intestinal reanimation. Here, we developed an ingestible self-propelling device for intestinal reanimation (INSPIRE) capable of restoring peristalsis through luminal electrical stimulation. Optimizing mechanical, material, and electrical design parameters, we validated optimal deployment, intestinal electrical luminal contact, self-propelling capability, safety, and degradation of the device in ex vivo and in vivo swine models. We compared the INSPIRE's effect on motility in models of normal and depressed motility and chemically induced ileus. Intestinal contraction improved by 44% in anesthetized animals and up to 140% in chemically induced ileus cases. In addition, passage time decreased from, on average, 8.6 days in controls to 2.5 days with the INSPIRE device, demonstrating significant improvement in motility. Luminal electrical stimulation of the intestine via the INSPIRE efficaciously restored peristaltic activity. This noninvasive option offers a promising solution for the treatment of ileus and other motility disorders.

Dexmedetomidine Has Differential Effects on the Contractility of Equine Jejunal Smooth Muscle Layers In Vitro

α2 agonists are frequently used in horses with colic, even though they have been shown to inhibit gastrointestinal motility. The aim of this study was to determine the effect of dexmedetomidine on small intestinal in vitro contractility during different phases of ischaemia. Experimental segmental jejunal ischaemia was induced in 12 horses under general anaesthesia, and intestinal samples were taken pre-ischaemia and following ischaemia and reperfusion. Spontaneous and electrically evoked contractile activity of the circular and longitudinal smooth muscles were determined in each sample with and without the addition of dexmedetomidine. During a second experiment, tetrodotoxin was added to determine if the effect was neurogenic. We found that the circular smooth muscle (CSM) contractility was not affected by ischaemia, whereas the longitudinal smooth muscle (LSM) showed an increase in both spontaneous and induced contractile activity. The addition of dexmedetomidine caused a decrease in the spontaneous contractile activity of CSM, but an increase in that of LSM, which was not mediated by the enteric nervous system. During ischaemia, dexmedetomidine also mildly increased the electrically induced contractile activity in LSM. These results may indicate a stimulatory effect of dexmedetomidine on small intestinal contractility. However, the influence of dexmedetomidine administration on intestinal motility in vivo needs to be further investigated.

Anesthesia and analgesia for common research models of adult mice

Anesthesia and analgesia are major components of many interventional studies on laboratory animals. However, various studies have shown improper reporting or use of anesthetics/analgesics in research proposals and published articles. In many cases, it seems "anesthesia" and "analgesia" are used interchangeably, while they are referring to two different concepts. Not only this is an unethical practice, but also it may be one of the reasons for the proven suboptimal quality of many animal researches. This is a widespread problem among investigations on various species of animals. However, it could be imagined that it may be more prevalent for the most common species of laboratory animals, such as the laboratory mice. In this review, proper anesthetic/analgesic methods for routine procedures on laboratory mice are discussed. We considered the available literature and critically reviewed their anesthetic/analgesic methods. Detailed dosing and pharmacological information for the relevant drugs are provided and some of the drugs' side effects are discussed. This paper provides the necessary data for an informed choice of anesthetic/analgesic methods in some routine procedures on laboratory mice.

A prospective study of intrapyloric botulinum toxin and EndoFLIP in children with nausea and vomiting

BACKGROUND

Intrapyloric botulinum toxin injection (IPBI) is used to treat nausea and vomiting in children, but no prospective pediatric studies exist. The aims of the current study were to assess the efficacy of IPBI in children with refractory nausea or vomiting and to use EndoFLIP as a biomarker of IPBI response.

METHODS

This was a prospective observational cohort study of pediatric patients undergoing IPBI for refractory nausea, vomiting, or feeding difficulties at a tertiary center. Patients completed validated questionnaires at baseline and 1, 2, and 3 months after IPBI. A subset of patients >10 years old underwent pyloric EndoFLIP at the time of IPBI. Symptoms were compared pre- and post-IPBI, and EndoFLIP measurements were assessed in relation to baseline characteristics and response to IPBI.

KEY RESULTS

Forty-five patients (mean age 14.2 ± 6.0 years) received IPBI, and 23 of those patients underwent EndoFLIP. Twenty-nine patients (64%) had symptomatic improvement at 1-month follow-up, including improvements in overall GI symptoms (p = 0.003), nausea and vomiting (p = 0.009), and discomfort when eating (p = 0.006). Symptomatic improvements lasted up to 3 months. There was a trend towards lower pyloric distensibility in patients with delayed versus normal gastric emptying (4.5 ± 3.8 mm2 /mmHg in delayed vs. 8.9 ± 6.6 mm2 /mmHg in normal, p = 0.09), though there were no differences in EndoFLIP measurements between IPBI responders and non-responders (p > 0.05).

CONCLUSIONS AND INFERENCES

The majority of patients responded to IPBI, with significant improvements seen in nausea, vomiting, and discomfort. Pyloric EndoFLIP tended to distinguish baseline delays in gastric emptying, but it did not predict IPBI response in this patient cohort.

Emerging Trends in Intestinal Knowledge Structure Associated With Acute Pancreatitis From 1981 to 2021: A Bibliometric Analysis

OBJECTIVES

Bibliometric analysis has not comprehensively summarized studies of acute pancreatitis (AP)-associated intestinal diseases. This work aimed to evaluate cooperative networks of authors, countries, and institutions and explore the field's developing trends and hot topics.

METHODS

Original articles and reviews of AP-associated intestinal diseases were obtained from the Web of Science Core Collection on October 11, 2021. VOSviewer and CiteSpace software were used to perform co-occurrence analyses for authors, countries, and institutions and detect the highest citation burst.

RESULTS

A total of 1634 articles on the intestine associated with AP were identified. The United States, the University of Auckland, and Roland Andersson are the most influential country, research institute, and scholar, respectively. The World Journal of Gastroenterology (73 articles) has the highest number of publications, and Gastroenterology was the most co-cited journal. The top 5 key words are "acute pancreatitis," "bacterial translocation," "management," "gut," and "inflammatory bowel disease." We find that several emergent key words like "gut microbiota," "pathway," "gut barrier," "risk," and "oxidative stress" experienced a continuous and rapid development as new research directions.

CONCLUSIONS

This bibliometric study summarizes current important perspectives and offers comprehensive guidance on the AP-associated intestinal diseases, which may help researchers choose the most appropriate research directions.

Impact of intravenous dexmedetomidine on gastrointestinal function recovery after laparoscopic hysteromyomectomy: a randomized clinical trial

Postoperative intestinal ileus is common after laparoscopic surgery, the incidence of those after hysterectomy was 9.2%. Anesthesia is one of the independent risk factors of postoperative ileus. Dexmedetomidine has been widely used in perioperative anesthesia and previous reports suggested that intraoperative dexmedetomidine may be associated with the improvement of gastrointestinal function recovery after abdominal surgery. We hypothesized that dexmedetomidine could improve gastrointestinal function recovery after laparoscopic hysteromyomectomy. Participants in elective laparoscopic hysteromyomectomy were enrolled with a single dose of 0.5 μg kg⁻¹ dexmedetomidine or the same volume of placebo intravenously administered for 15 min, followed by continuous pumping of 0.2 μg kg⁻¹ h⁻¹ of corresponding drugs until 30 min before the end of surgery. The primary outcome was the time to first flatus. Secondary outcomes were the time to first oral feeding and the first defecation, the occurrence of flatulence, pain score and postoperative nausea and vomiting until 48 h after the surgery. Eventually, 106 participants (54 in dexmedetomidine group and 52 in placebo group) were included for final analysis. The time to first flatus (SD, 25.83 [4.18] vs 27.67 [3.77], P = 0.019), oral feeding time (SD, 27.29 [4.40] vs 28.92 [3.82], P = 0.044), the time to first defecation (SD, 59.82 [10.49] vs 63.89 [7.71], P = 0.025), abdominal distension (n%, 12 (22.2) vs 21 (40.4), P = 0.044), PONV at 24 h (n%, 10 (18.5) vs 19 (36.5), P = 0.037), NRS 6 h (3.15(0.68) vs 3.46 (0.87), P = 0.043) and NRS 12 h (3.43 (0.88) vs 3.85 (0.85), P = 0.014) of dexmedetomidine group were significantly shorter than those of the placebo group. Intraoperative dexmedetomidine reduced the time to first flatus, first oral feeding, and first defecation. These results suggested that this treatment may be a feasible strategy for improving postoperative gastrointestinal function recovery in patients undergoing laparoscopic hysteromyomectomy.

Evaluation of the effect of different sedative doses of dexmedetomidine on the intestinal motility in clinically healthy donkeys (Equus asinus)

AIM

Gastrointestinal effects of different doses of dexmedetomidine in donkeys are still unidentified. The current study aimed to evaluate the impact of different doses of dexmedetomidine on the motility of selected parts of the gastrointestinal tracts in donkeys using transabdominal ultrasonography.

MATERIALS AND METHODS

An experimental crossover study was conducted on 30 healthy donkeys of both sexes (15 males and 15 females; 160 ± 60 kg). With a two-week washout period, each donkey received an injection of either a normal saline solution or three different doses of dexmedetomidine (3, 5, and 7 μg/kg, respectively). All medications were administered intravenously in equal volumes. The contractility of selected intestinal segments (duodenum, jejunum, left colon, right colon, and cecum) was measured 3 min before administration (zero time) and at 15, 30, 45, 60, 90, and 120 minutes after administration.

RESULTS

Small and large intestinal motility was within the normal ranges before IV injection of normal isotonic saline or dexmedetomidine at a dose of 3, 5, and 7 μg/kg. Two Way Repeated Measures ANOVA output of the data displayed a statistically significant the between time and treatments for the contractility of each of the duodenum (P = 0.0029), jejunum (P = 0.0033), left colon (P = 0.0073), right colon (P = 0.0035), and cecum (P = 0.0026), implying that the impact of treatment on the gastric motility varied among different time points. The simple main effect analysis revealed that the IV dexmedetomidine at 3, 5, and 7 μg/kg doses significantly inhibited (P ≤ 0.01) the bowel contractility compared to the administration of isotonic saline.

CONCLUSION

Dose-dependent inhibitory effect of dexmedetomidine on intestinal motility was reported in donkeys following intravenous administration. This inhibitory effect on intestinal motility should be considered in clinical practice.

Stimulating peristalsis improves esophagogastric junction observation during sedated esophagogastroduodenoscopy in children and adolescents

Background and study aims

Sedation impairs full visualization of the esophagogastric junction (EGJ) and Z line (the squamocolumnar junction) during esophagogastroduodenoscopy (EGD). The aim of this study was to determine whether induction of esophageal peristalsis could improve the ability to evaluate the Z line in children and adolescents.

Patients and methods

Study 1: Consecutive patients (10-15 years) undergoing EGD with propofol or midazolam sedation were enrolled. The proportion of Z line observed was compared between the two groups. Study 2: The effect of an air infusion near the EGJ following deflation of the stomach to induce esophageal peristalsis was investigated in the patients (15-18 years), undergoing EGD with propofol sedation. The proportion of Z line observed was compared between the stimulated group and control group.

Results

Study 1: 149 patients were evaluated; 87 received propofol (43 boys; average age 13.2 years (range, 10-15)) and 62 received midazolam (30 boys; average age 12.8 years (range, 10-15)). The proportion of the Z line visualized was low but was greater with propofol vs. midazolam sedation (36.8% vs 16.1%, P=0.0059). Study 2: 102 patients were evaluated; 62 had induction of peristalsis (34 boys; average age 16.2 years (range, 15-18)) and 40 controls (20 boys; average age 16.8 years (range, 15-18)). Complete visualization of the Z line achieved in 95% (59 of 62) following induction of peristalsis vs. 37.5% (15 of 40) of controls (P>0.001).

Conclusions

Induction of esophageal peristalsis greatly improved visualization of the Z line during sedated EGD in children and adolescents.

Acute Colonic Pseudo-Obstruction Following the Use of Dexmedetomidine

Dexmedetomidine is a preferred agent for light sedation with minimal adverse effects. We report a case of acute colonic pseudo-obstruction following dexmedetomidine use in a patient with alcohol withdrawal. He was treated with benzodiazepines first to control the withdrawal symptoms, then escalated to dexmedetomidine once delirium tremens ensued. Later on, the patient developed abdominal distension and vomiting. Imaging showed dilated bowel loops and absence of peristalsis on ultrasound. Decompression with the nasogastric (NG) tube was done, with high output from the NG tube. Dexmedetomidine infusion was used twice, and once it was stopped, the NG tube output was reduced, with the resumption of gastrointestinal motility and improvement of the abdominal distension. Recent similar reports of functional intestinal obstruction following alpha-2 (α2) agonist use necessitate further studies of intestinal motility following dexmedetomidine use and awareness of the possible side effect of dexmedetomidine on intestinal motility.