Esketamine counters opioid-induced respiratory depression

The effect and mechanism of low-dose esketamine in neuropathic pain-related depression-like behavior in rats

BACKGROUND

Clinical evidence suggests that Esketamine (ESK) is an effective treatment for depression. However, the effects of Esketamine in treating depression-like behavior induced by neuropathic pain is unclear. The underlying molecular mechanisms require further investigation to provide new therapeutic targets for the treatment of clinical neuropathic pain-related depression.

METHODS

A neuropathic pain-related depression model was established in rats with spared nerve injury (SNI). Male Sprague-Dawley rats were randomly divided into four groups: Sham Group, SNI group, SNI + Normal Saline (NS) Group and SNI + ESK5mg/kg Group. Mechanical pain thresholds were measured to assess pain sensitivity in SNI rats. On the 14th day after surgery a forced swim test and sucrose preference test were used to evaluate the depressive-like behavior of rats in each group. Further, a proteomic analysis was used to quantify differentially expressed proteins. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were analyzed to explore the main protein targets of SNI in the medial prefrontal cortex. The expression of proteins was detected by Western blotting.

RESULTS

A neuropathic pain-related depression model was established. Compared with the Sham group, the mechanical pain threshold was decreased significantly (13.2 ± 1.0 vs. 0.7 ± 0.01 g n = 8), while immobility on the forced swim test was also decreased (93.1 ± 7.4 vs. 169.5 ± 9.6 s n = 8), and sucrose preference rate was significantly increased (98.8 ± 0.3 vs. 73.1 ± 1.4n = 7) in SNI group rats. Compared with the SNI + NS group, the mechanical pain threshold was not statistically significant, while immobility on the forced swim test was clearly decreased (161.1 ± 11.6 vs. 77.9 ± 5.0 s n = 8), and sucrose preference rate was significantly increased (53.1 ± 8.9 vs. 96.1 ± 1.4n = 7) in SNI + ESK5mg/kg group rats. To further investigate the underlying mechanism, we employed proteomics to identify proteins exhibiting more than a 1.2-fold difference (P < 0.05) in expression levels within each group for subsequent analysis. Relative to the Sham group, 88 downregulated and 104 up-regulated proteins were identified in the SNI group, while 120 and 84 proteins were up- and down-regulated in the Esketamine treatment group compared with the SNI + NS group. Compared with Sham group, the expressions of mGluR5 and Homer1a were up-regulated in the medial prefrontal cortex (mPFC) in SNI group (mGluR5:0.97 ± 0.05 vs 1.47 ± 0.15, Homer1a:1.03 ± 0.06 vs 1.46 ± 0.16n = 6), and down-regulated after intervention with Esketamine (mGluR5:1.54 ± 0.11 vs 1.06 ± 0.07, Homer1a:1.51 ± 0.13 vs 1.12 ± 0.34n = 6).

CONCLUSIONS

Low-dose Esketamine appeared to relieve depression-like behavior induced by neuropathic pain. The Homer1a-mGluR5 signaling pathway might be the mechanism of antidepressant effect of Esketamine.

Efficacy of nonopioid analgesics and adjuvants in multimodal analgesia for reducing postoperative opioid consumption and complications in obesity: a systematic review and network meta-analysis

BACKGROUND

Managing postoperative pain in patients with obesity is challenging. Although multimodal analgesia has proved effective for pain relief, the specific impacts of different nonopioid i.v. analgesics and adjuvants on these patients are not well-defined. This study aims to assess the effectiveness of nonsteroidal antiinflammatory drugs, paracetamol, ketamine, α-2 adrenergic receptor agonists, lidocaine, magnesium, and oral gabapentinoids in reducing perioperative opioid consumption and, secondarily, in mitigating the occurrence of general and postoperative pulmonary complications (POPCs), nausea, vomiting, PACU length of stay (LOS), and hospital LOS among surgical patients with obesity.

METHODS

A systematic review and network meta-analysis was performed. PubMed, Scopus, Web of Science, CINAHL, and EMBASE were searched. Only English-language RCTs investigating the use of nonopioid analgesics and adjuvants in adult surgical patients with obesity were included. The quality of evidence and certainty were assessed using the RoB 2 tool and GRADE framework, respectively.

RESULTS

In total, 37 RCTs involving 3602 patients were included in the quantitative analysis. Compared with placebo/no intervention or a comparator, dexmedetomidine, ketamine, lidocaine, magnesium, and gabapentin significantly reduced postoperative opioid consumption after surgery. Ketamine/esketamine also significantly reduced POPCs. Ibuprofen, dexmedetomidine, and lidocaine significantly reduced postoperative nausea, whereas dexmedetomidine, either alone or combined with pregabalin, and lidocaine reduced postoperative vomiting. Dexmedetomidine significantly reduced PACU LOS, whereas both paracetamol and lidocaine reduced hospital LOS.

CONCLUSIONS

Intravenous nonopioid analgesics and adjuvants are crucial in multimodal anaesthesia, reducing opioid consumption and enhancing postoperative care in adult surgical patients with obesity.

SYSTEMATIC REVIEW PROTOCOL

CRD42023399373 (PROSPERO).

Impact of different doses of esketamine on the incidence of hypotension in propofol-based sedation for colonoscopy: a randomized controlled trial

Background

Hypovolemia is common in colonoscopy due to fasting and bowel preparation, and propofol itself can reduce systemic vascular resistance, resulting in relative hypovolemia. Therefore, hypotension is not a rare event during propofol-based sedation for colonoscopy.

Objectives

Our objective was to explore the efficacy of esketamine as a sedative adjuvant in reducing the incidence of hypotension during colonoscopy.

Design

This was a prospective randomized trial. The trial was registered with the Chinese Clinical Trial Registry (ID: ChiCTR 2100047032).

Methods

We included 100 eligible patients who planned to receive a colonoscopy and randomly divided them into 4 groups with 25 patients in each group, which were propofol 2 mg/kg (Group P), propofol 1 mg/kg with esketamine 0.2 mg/kg (Group E1), propofol 1 mg/kg with esketamine 0.3 mg/kg (Group E2), and propofol 1 mg/kg with esketamine 0.4 mg/kg (Group E3). The hemodynamic and respiratory parameters were documented at various times during the procedure, including the patient's entry into the endoscopic room (T0), the induction of sedation (T1), the insertion of the colonoscope (T2), the removal of the colonoscope (T3), and the awakening of the patient (T4). The primary outcome was the incidence of hypotension. Secondary outcomes were cardiovascular side effects other than hypotension, incidence of hypoxia, cumulative changes in cardiovascular and respiratory parameters, total propofol dosage, anesthesia recovery time, and satisfactory levels of both patients and endoscopists.

Results

The incidence of hypotension in Group E1 (16%), Group E2 (16%), and Group E3 (12%) was significantly lower than in Group P (60%), with p values 0.003, 0.003, and <0.001 respectively. The cumulative changes in diastolic blood pressure and mean arterial pressure in Groups E1, E2, and E3 were significantly higher than in Group P (p = 0.024, p < 0.001, p = 0.006, respectively). Cumulative changes in systolic blood pressure in Group E3 were significantly higher than those in Group P (p = 0.012). The respiratory-related parameters were not statistically significant.

Conclusions

This study showed that the application of 0.4 mg/kg esketamine in propofol-based sedation reduced the incidence of hypotension during colonoscopy while providing satisfactory sedation.

Opioid-free anesthesia improves postoperative recovery quality of small and medium-sized surgery: a prospective, randomized controlled study

BACKGROUND

Opioid anesthesia (OA) is currently the predominant anesthetic method. However, its associated side effects, such as nausea and vomiting, coupled with the principle of enhanced recovery after surgery (ERAS), have spurred the adoption of opioid-free anesthesia (OFA) in select surgical procedures. For small and medium-sized operations, ERAS is particularly important. The aim of this study was to investigate the effect of OFA, utilizing esketamine in combination with dexmedetomidine and sevoflurane, on postoperative recovery quality following small and medium-sized surgical interventions.

METHODS

A total of 120 patients who underwent various small and medium-sized operations were randomly allocated to OFA and OA groups. The OA group received sufentanyl and sevoflurane, while the OFA group received esketamine, dexmedetomidine, and sevoflurane. The primary outcome measure was the postoperative quality of recovery-40 scores (QoR-40) 24 hours after surgery. Secondary outcomes included hemodynamic changes at different time intervals, the incidences of adverse events were recorded.

RESULTS

Patients in the OFA group exhibited a higher QoR-40 score of 184.0 (182.0, 186.2) compared to 182.0 (180.0, 184.0) in the OA group (P<0.001). The disparities were particularly noble in terms of Physical comfort and Emotional status. Multivariable analysis identified postoperative nausea and vomiting (PONV) as a significant independent factor impacting QoR-40 (β=-4.49 [-6.1, -2.87], P<0.001). Hemodynamic stability was more pronounced in the OFA than in the OA group. The incidence of PONV was substantially lower in the OFA group (one [1.6%] vs. 14 [25%], P<0.001), with a reduced need for vasoactive drugs (five [7.8%] vs. 15 [26.8%], P=0.005), and a lower incidence of respiratory depression (0 [0%] vs. six [10.7%], P=0.009).

CONCLUSIONS

OFA improves the postoperative recovery quality in small and medium-sized surgical procedures, potentially attributed to decreased incidence of PONV. Additionally, OFA facilitates the maintenance of more stable hemodynamics throughout the operation.

Comparison Between Esketamine and Alfentanil for Hysteroscopy: A Prospective, Double-Blind, Randomized Controlled Trial

Purpose

This study aimed to establish the 95% effective dose (ED95) of esketamine in combination with propofol for hysteroscopy and then to evaluate its efficacy and safety profile.

Patients and Methods

This prospective, double-blind, randomized controlled trial consisted of two cohorts. In cohort 1, 45 women aged 18-65 years undergoing hysteroscopy were randomly assigned to either group E (esketamine + propofol) or group A (alfentanil + propofol). Dixon's up-and-down method was used to determine the ED95 of esketamine and alfentanil. In cohort 2, 86 patients were randomized to group E and group A, with the calculated ED95 dose of the study drugs used for induction. The success rate of anesthesia using the ED95% dose, along with parameters related to anesthesia induction, recovery, and adverse events were also recorded.

Results

The ED95 of esketamine was 0.254 mg/kg (95% CI: 0.214-1.004), while that of alfentanil was 9.121 μg/kg (95% CI: 8.479-13.364). The anesthesia success rate was 93.0% in group E and 95.2% in group A (p = 0.664). After resuscitation, both groups achieved a 100% success rate. The induction time was significantly shorter in group E (60.0 [55.0-70.0] s) compared to group A (67.0 [61.0-79.3] s) (p = 0.006). Group E had lower rates of respiratory depression (p < 0.001), hypoxia (p = 0.006), minimum perioperative SpO2 (p = 0.010), and hypotension (p = 0.001). Esketamine had less effect on respiratory rate, heart rate, mean blood pressure, and end-tidal carbon dioxide compared to alfentanil (all p < 0.001). There were no significant differences in postoperative pain between the two groups.

Conclusion

This study determined the ED 95 dose of esketamine for intravenous general anesthesia during hysteroscopy. Esketamine showed less respiratory and hemodynamic depression, as well as fewer adverse effects compared to alfentanil. Esketamine is an ideal anesthetic agent compared to alfentanil for hysteroscopic anesthesia.

Trial Registration

www.chictr.org.cn, (ChiCTR2300077283); registered November 3, 2023.

Advances in attenuating opioid-induced respiratory depression: A narrative review

Opioids exert analgesic effects by agonizing opioid receptors and activating signaling pathways coupled to receptors such as G-protein and/or β-arrestin. Concomitant respiratory depression (RD) is a common clinical problem, and improvement of RD is usually achieved with specific antagonists such as naloxone; however, naloxone antagonizes opioid analgesia and may produce more unknown adverse effects. In recent years, researchers have used various methods to isolate opioid receptor-mediated analgesia and RD, with the aim of preserving opioid analgesia while attenuating RD. At present, the focus is mainly on the development of new opioids with weak respiratory inhibition or the use of non-opioid drugs to stimulate breathing. This review reports recent advances in novel opioid agents, such as mixed opioid receptor agonists, peripheral selective opioid receptor agonists, opioid receptor splice variant agonists, biased opioid receptor agonists, and allosteric modulators of opioid receptors, as well as in non-opioid agents, such as AMPA receptor modulators, 5-hydroxytryptamine receptor agonists, phosphodiesterase-4 inhibitors, and nicotinic acetylcholine receptor agonists.

Observation on the Analgesic Effect of Different Doses of a Combination of Esketamine and Dexmedetomidine Administered for Percutaneous Endoscopic Transforaminal Discectomy: A Randomized, Double-Blind Controlled Trial

BACKGROUND

Percutaneous endoscopic transforaminal discectomy (PETD) is an effective method for treating lumbar disc herniation, and is typically performed under local anesthesia. However, inadequate analgesia during the procedure remains a concern, prompting the search for a medication that can provide optimal pain control with minimal impact on the respiratory and circulatory systems.

OBJECTIVES

The aim of this study was to observe the effects of different doses of esketamine combined with dexmedetomidine on reducing visual analog scale (VAS) scores during surgical interventions.

METHODS

One hundred two patients who underwent PETD were randomly divided into a control group (group C: normal saline + dexmedetomidine), an E1 group (0.1 mg kg-1 esketamine + dexmedetomidine), and an E2 group (0.2 mg kg-1 esketamine + dexmedetomidine). The primary outcome was the maximum visual analogue scale (VAS) (score: 0 = no pain and 10 = worst pain) at six time points. The secondary outcomes included the Assessment of Alertness/Sedation Scale (OAA/S) score and mean arterial pressure (BP), heart rate (HR), respiratory rate (RR), and oxygen saturation (SpO2) at 11 time points. The incidence of adverse reactions during and 24 h after the operation and patient satisfaction with the anesthesia were also recorded.

RESULTS

Compared with those in group C, the VAS scores of patients in groups E1 and E2 were lower at T6, T7, and T9 (P < 0.05). From T4 to T10, the OAA/S scores of the E1 and E2 groups were both lower than those of group C (P < 0.05), and at the T4-T6 time points, the OAA/S score of the E2 group was lower than that of group E1 (P < 0.05). At T4 and T5, the HR and BP of patients in groups E1 and E2 were greater than those in group C (P < 0.05). Compared with those in group C, the incidences of intraoperative illusion, floating sensation, postoperative dizziness, and hyperalgesia in groups E1 and E2 were significantly greater (P < 0.01). There was no significant difference in patient RR, SpO2, or postoperative satisfaction with anesthesia among the three groups (P > 0.05).

CONCLUSION

The combination of esketamine and dexmedetomidine can reduce VAS scores during certain stages of this type of surgery; it has minimal impact on respiration and circulation. However, this approach is associated with increased incidences of postoperative dizziness and psychiatric side effects, which may also affect patients' compliance with surgical instructions from medical staff. Patient satisfaction was not greater with dexmedetomidine combined with esketamine than with dexmedetomidine alone.

TRIAL REGISTRATION

http://www.chictr.org.cn . Identifier: ChiCTR2300068206. Date of registration: 10 February 2023.

Effect of esketamine on the ED50 of propofol for successful insertion of ureteroscope in elderly male patients: a randomized controlled trial

BACKGROUND

Propofol is effective and used as a kind of routine anesthetics in procedure sedative anesthesia (PSA) for ureteroscopy. However, respiratory depression and unconscious physical activity always occur during propofol-based PSA, especially in elderly patients. Esketamine has sedative and analgesic effects but without risk of cardiorespiratory depression. The purpose of this study is to investigate whether esketamine can reduce the propofol median effective dose (ED50) for successful ureteroscope insertion in elderly male patients.

MATERIALS AND METHODS

49 elderly male patients undergoing elective rigid ureteroscopy were randomly divided into two groups: SK Group (0.25 mg/kg esketamine+propofol) and SF Group (0.1 µg/kg sufentanil+propofol). Patients in both two groups received propofol with initial bolus dose of 1.5 mg/kg after sufentanil or esketamine was administered intravenously. The effective dose of propofol was assessed by a modified Dixon's up-and-down method and then was adjusted with 0.1 mg/kg according to the previous patient response. Patients' response to ureteroscope insertion was classified as "movement" or "no movement". The primary outcome was the ED50 of propofol for successful ureteroscope insertion with esketamine or sufentanil. The secondary outcomes were the induction time, adverse events such as hemodynamic changes, hypoxemia and body movement were also measured.

RESULT

49 patients were enrolled and completed this study. The ED50 of propofol for successful ureteroscope insertion in SK Group was 1.356 ± 0.11 mg/kg, which was decreased compared with that in SF Group, 1.442 ± 0.08 mg/kg (P = 0.003). The induction time in SK Group was significantly shorter than in SF Group (P = 0.001). In SK Group, more stable hemodynamic variables were observed than in SF Group. The incidence of AEs between the two groups was not significantly different.

CONCLUSION

The ED50 of propofol with esketamine administration for ureteroscope insertion in elderly male patients is 1.356 ± 0.11 mg/kg, significantly decreased in comparsion with sufentanil.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, No: ChiCTR2300077170. Registered on 1 November 2023. Prospective registration. http://www.chictr.org.cn .

Efficacy and safety of esketamine for pediatric gastrointestinal endoscopy: a meta-analysis and trial sequential analysis

Objective

The role of esketamine in pediatric gastrointestinal endoscopy is still unclear. This study aims to evaluate the efficacy and safety of esketamine for pediatric gastrointestinal endoscopy.

Methods

Clinical trials of esketamine for pediatric gastrointestinal endoscopy were searched in eight common databases, up to October 2023. These clinical trials were included in the meta-analysis and trial sequential analysis (TSA). The risk ratio (RR) and weighted mean difference (WMD) were used as the effect sizes for dichotomous variables and continuity variables, respectively. When the heterogeneity test showed I2 < 50%, the fixed effects model was used for the meta-analysis and TSA; Otherwise, the random effects model was used for them.

Results

In terms of efficacy endpoints, the meta-analysis showed that compared with placebo or blank, esketamine significantly decreased recovery time by 2.34 min (WMD -2.34; 95% Confidence interval [CI] -3.65, -1.02; p = 0.0005) and propofol consumption by 0.70 mg/kg (WMD -0.70; 95% CI -0.98, -0.43; p < 0.00001), and increased mean heart rate by 4.77 beats/min (WMD 4.77; 95% CI 2.67, 6.87; p < 0.00001) and mean arterial pressure by 3.10 mmHg (WMD 3.10; 95% CI 1.52, 4.67; p = 0.0001), while induction time and mean blood oxygen remained comparable. TSA indicated conclusive evidence for these benefits. In terms of safety endpoints, the meta-analysis revealed that esketamine significantly reduced involuntary movements by 59% (RR 0.41; 95% CI 0.22, 0.76; p = 0.005) and choking by 51% (RR 0.49; 95% CI 0.26, 0.92; p = 0.03), while significantly increasing dizziness by 98% (RR 1.98; 95% CI 1.11, 3.56; p = 0.02) and there were no significant differences in total adverse events, respiratory depression, and vomiting. TSA demonstrated conclusive evidence for involuntary movements and dizziness. Low-dose analysis showed that esketamine at ≤0.3 mg/kg significantly reduced recovery time, propofol consumption and involuntary movements, and significantly increasing mean heart rate, with no increase in dizziness. The Begg's test (p = 0.327) and the Egger's test (p = 0.413) indicated no significant publication bias, yet the funnel plot suggested potential publication bias.

Conclusion

Esketamine is an effective adjuvant anesthesia for children undergoing gastrointestinal endoscopy. However, the general dose of esketamine may increase the risk of dizziness, which can be avoided by administering a low dose (≤0.3 mg/kg).

Application of OFA-based ERAS for video-assisted thoracoscopic surgery in elderly patients with airway stenosis: A case report

BACKGROUND

Thoracic surgery without general anesthesia can be traced back to the First World War, and thoracic epidural block was used to complete the operation due to a large number of patients with gunshot wounds who needed emergency thoracic surgery. By reducing the intraoperative opioid dose, intraoperative and postoperative opioid-related adverse events such as respiratory depression, nausea and vomiting, delirium, hyperalgesia, and other side effects can be reduced to the benefit of patients.

METHODS

A 72-year-old male patient was admitted to the hospital with a 5-day history of multifocal pain throughout the body caused by a fall. The injury was not treated at that time, and the pain gradually increased, accompanied by cough with difficulty expelling sputum.

DIAGNOSES

Left lung contusion; traumatic pneumonia; multiple left rib fractures; left fluid pneumothorax; thyroid tumor of unknown nature, possibly malignant. Grade I tracheal stenosis; Sequelae of cerebral infarction. Because of goiter and severe tracheal compression, the patient was not intubated and received deopiated general anesthesia combined with epidural anesthesia to preserve spontaneous breathing.

OUTCOMES

At the end of the video-assisted thoracoscopic exploration, the patient was immediately conscious and returned directly to the ward 6 min later. The patient was able to move freely after surgery and eat normally within 6 h of surgery. The postoperative visual analog scale score was 2 points, and there were no anesthetic complications during the follow-up.

CONCLUSION

The opioid-free anesthesia strategy of tubeless general anesthesia, allowing spontaneous breathing combined with epidural anesthesia in elderly patients with tracheal stenosis undergoing video-assisted thoracoscopic surgery can not only avoid accidents and injuries caused by tracheal intubation and mechanical ventilation, but can also significantly reduce postoperative respiratory complications, optimize postoperative analgesia, and help achieve enhanced recovery after surgery.

Efficacy and safety of low-dose esketamine for painless gastrointestinal endoscopy in adults: a systematic evaluation and meta-analysis

Object: The benefits of low-dose esketamine for painless gastrointestinal endoscopy remain unclear. As such, the present study aimed to investigate the efficacy and safety of low-dose esketamine for this procedure. Methods: Seven common databases were searched for clinical studies investigating low-dose esketamine for painless gastrointestinal endoscopy. Subsequently, a meta-analysis was performed to synthesize and analyze the data extracted from studies fulfilling the inclusion criteria. Results: Meta-analysis revealed that, compared with propofol, low-dose esketamine in combination with propofol significantly reduced recovery time by 0.56 min (mean difference [MD] -0.56%, 95% confidence interval (CI) -1.08 to -0.05, p = 0.03), induction time by 9.84 s (MD -9.84, 95% CI -12.93 to -6.75, p < 0.00001), propofol dosage by 51.05 mg (MD -51.05, 95% CI -81.53 to -20.57, p = 0.01), and increased mean arterial pressure by 6.23 mmHg (MD 6.23, 95% CI 1.37 to 11.08, p = 0.01). Meanwhile, low-dose esketamine reduced injection pain by 63% (relative risk [RR] 0.37, 95% CI 0.28 to 0.49, p < 0.00001), involuntary movements by 40% (RR 0.60, 95% Cl 0.42 to 0.85, p < 0.005), choking by 42% (RR 0.58, 95% Cl 0.38 to 0.88, p = 0.01), bradycardia by 68% (RR 0.32, 95% Cl 0.18 to 0.58, p = 0.0002), hypotension by 71% (RR 0.29, 95% Cl 0.21 to 0.40, p < 0.00001), respiratory depression by 63% (RR 0.37, 95% 0.26 to 0.51, p < 0.00001), additional cases of propofol by 53% (RR 0.47, 95% Cl 0.29 to 0.77, p = 0.002), and increased hypertension by 1000% (RR 11.00, 95% Cl 1.45 to 83.28, p = 0.02). There were no significant differences in mean heart rate, mean oximetry saturation, delirium, dizziness, vomiting, tachycardia, and hypoxemia. Subgroup analyses revealed that, compared with other dose groups, 0.25 mg/kg esketamine afforded additional benefits in recovery and induction time, mean arterial pressure, involuntary movements, hypoxemia, and respiratory depression. Conclusion: Low-dose esketamine was found to be safe and effective for providing anesthesia during gastrointestinal endoscopy, with 0.25 mg/kg identified as the optimal dose within the dosage ranges examined. However, caution should be exercised when administering this drug to patients with inadequate preoperative blood pressure control.

Efficacy and safety of esketamine combined with propofol for curative endoscopic resection in colorectum: a prospective, randomized controlled trial

BACKGROUND

Curative endoscopic resection is widely used to treat colonic polyps and early stage cancers. The anesthetic strategy commonly involves the use of propofol combined with a small dose of opioids for sedation. Adverse respiratory or cardiovascular events such as hypotension often occur when attempting to achieve the necessary level of sedation. Several studies have suggested its advantages owing to the anesthetic, analgesic, and sympathomimetic properties of esketamine. However, there are no reports on curative colorectal endoscopic resection. We designed this randomized controlled trial to assess the efficacy and safety of esketamine combined with propofol for sedation in patients undergoing curative colorectal endoscopic resection.

METHODS

A total of 166 patients who underwent curative colorectal endoscopic resection were randomly assigned to groups A (propofol + fentanyl) or E (propofol + esketamine). Ideal sedation was assessed using the MOAA/S scale and was achieved using TCI-propofol with different doses of fentanyl and esketamine. The propofol consumption and vasoactive drug dosages were recorded. Sedation-related times, adverse events, and satisfaction were recorded.

RESULTS

Of the 160 patients, the total propofol consumption was significantly lower in group E (n = 81) (300 mg) than in group A (n = 79) (350 mg). Hypotension and bradycardia were significantly lower in Group E than in Group A. The groups showed no significant differences in other adverse events, induction time, recovery time, or patient or endoscopist satisfaction.

CONCLUSION

Compared to fentanyl, esketamine helps decrease propofol consumption and increases cardiovascular stability during curative colorectal endoscopic resection in American Society of Anesthesiologists Class I-III patients without affecting anesthesia, patient and endoscopist satisfaction, or other adverse events.

TRIAL REGISTRATION

The study was retrospectively registered at the Chinese Clinical Trial Registry ( www.chictr.org.cn ; registration number: ChiCTR2300069014 on 03/03/2023).

Supplemental low-dose esketamine to propofol versus propofol alone on perioperative characteristics in children undergoing surgery: a prospective randomized controlled trial

BACKGROUND

Limited data exist regarding the use of the esketamine-propofol combination (esketofol) in pediatric surgery. This study aimed to investigate the effect of esketofol versus propofol alone on the perioperative characteristics of children undergoing minor surgery.

METHODS

Eighty-four children aged two to six years were randomly assigned to either the propofol group or the esketofol group. Intraoperative outcomes included bispectral index, dosage of anesthetics, and extubation time. Postoperative outcomes comprised oropharyngeal airway usage, time to orientation, time to eye-opening, length of stay in the post-anesthesia care unit, the need for rescue opioids, pain rating using the Face, Legs, Activity, Cry, Consolability (FLACC) Scale, Pediatric Anesthesia Emergence Delirium Score, nausea and vomiting, and psychotomimetic symptoms. The FLACC pain score was the primary outcome, and the remaining parameters were considered secondary outcomes.

RESULTS

The FLACC Score (2 [1, 3.3] vs. 4 [3, 5.3], P<0.001) and frequency of rescue opioids (14.3% vs. 33.3%, P=0.040) were significantly lower, while Bispectral Index (BIS) was higher (P<0.001) in the esketofol group compared with the propofol group. Moreover, the time to orientation and length of stay in the post-anesthesia care unit (PACU) were significantly longer in the esketofol group compared with the propofol group (P=0.029 and P=0.025, respectively). The other outcomes were similar between the two groups.

CONCLUSIONS

Esketofol reduces postoperative pain and the need for rescue opioids, but it extends recovery time in the PACU and increases BIS without affecting other outcomes.

Effect of esketamine on the EC50 of remifentanil for blunting cardiovascular responses to endotracheal intubation in female patients under general anesthesia: a sequential allocation dose-finding study

BACKGROUND

This study aimed to investigate the effect of esketamine on the dose-effect relationship between remifentanil and the cardiovascular response to endotracheal intubation during target-controlled infusion (TCI) of propofol.

METHODS

Patients underwent elective gynecological laparoscopic surgery under general anesthesia with endotracheal intubation, aged 18-65 years, American Society of Anesthesiologists class I or II, 18 kg/m2 ≤ body mass index ≤ 30 kg/m2, were randomly divided into the control (group C) and esketamine groups (group E). Before anesthesia induction, group E received an intravenous injection of 0.3 mg/kg of esketamine, while group C received an equal dose of physiological saline. TCI of propofol to the effect-site concentration (EC) of 3.0 μg/mL, and then TCI of remifentanil to the effect room and intravenous injection of rocuronium 0.6 mg/kg after MOAA/S was 0. Endotracheal intubation was performed after 2 min. Dixon's modified sequential method was used, and the initial EC of remifentanil was 3.0 ng/mL. The EC of remifentanil was determined according to the intubation response of the previous patient, with an adjacent concentration gradient of 0.3 ng/mL. The EC50 and EC95 values and their 95% confidence intervals (CIs) were determined using probit regression analysis.

RESULTS

The EC50 for cardiovascular response inhibition to endotracheal intubation using remifentanil was 3.91 ng/mL (95% CI: 3.59-4.33 ng/mL) and EC95 was 4.66 ng/mL (95% CI: 4.27-6.23 ng/mL) with TCI of propofol 3.0 μg/mL. After intravenous administration of 0.3 mg/kg of esketamine, the EC50 of remifentanil was 3.56 ng/mL (95% CI: 3.22-3.99 ng/mL) and EC95 was 4.31 ng/mL (95% CI: 3.91-5.88 ng/mL).

CONCLUSIONS

Combined with TCI of propofol 3.0 μg/mL for anesthesia induction, esketamine significantly reduced the EC50 and EC95 of remifentanil to inhibit the cardiovascular response to endotracheal intubation.

TRIAL REGISTRATION

The trial was registered in the Chinese Clinical Trials Registry ( www.chictr.org.cn ; registration number: ChiCTR2200064932; date of registration:24/10/2022).

Postoperative esketamine improves ventilation after video-assisted thoracoscopic lung resection: A double-blinded randomized controlled trial

Background

Pain management after lung resection plays a crucial role in reducing postoperative pulmonary complications (PPCs). This study aimed to examine the effect of postoperative esketamine infusion as an adjunct to opioid analgesia on ventilation and pulmonary complications in patients underwent lung resection.

Methods

Patients undergoing video-assisted thoracoscopic lung resection were randomly assigned to either the esketamine group or the control group. The esketamine group received a 24-h infusion of 1.5 mcg/ml sufentanil combined with 0.75 mcg/ml esketamine after surgery, while the control group received 1.5 mcg/ml sufentanil alone. The primary outcome measure was low minute ventilation, and the secondary outcome measures were hypoxemia, PaO2/FiO2 levels, postoperative pulmonary complications, hospital stay duration, ambulation time, Visual Analogue Scale (VAS) score, depression and anxiety levels, sleep quality, and analgesia satisfaction.

Results

80 patients were randomly divided into two groups: the esketamine group (n = 40) and the control group (n = 40). The esketamine group exhibited notably reduced incidence of low minute ventilation (P = 0.014), lower occurrence of postoperative pulmonary complications (PPCs) compared to the control group (P = 0.039), and decreased incidence of hypoxemia (P = 0.003). Furthermore, the esketamine group showed improved outcomes with lower VAS scores on the second postoperative day and enhanced sleep quality (P < 0.001) after the surgery.

Conclusions

Postoperative esketamine infusion with opioids improved ventilation and reduced PPCs after lung resection, warranting further clinical studies.

Trial registration

This study was registered on ClinicalTrials.gov (Trial ID: NCT05458453, https://clinicaltrials.gov/ct2/show/NCT05458453).

Effect of esketamine-based opioid-sparing anesthesia strategy on postoperative pain and recovery quality in patients undergoing total laparoscopic hysterectomy: A randomized controlled trail

Objective

Opioid-sparing anesthesia reduces intraoperative use of opioids and postoperative adverse reactions. The current study investigated the effect of esketamine-based opioid-sparing anesthesia on total laparoscopic hysterectomy patients' recovery.

Methods

Ninety patients undergoing total laparoscopic hysterectomy were randomly assigned to esketamine-based group (group K) or opioid-based group (group C). The allocation to groups was unknown to patients, surgeons, and postoperative medical staff. The inability to implement blinding for anesthesiologists was due to the distinct procedures followed by the various groups while administering drugs. The QoR-40 and VAS were used to measure recovery quality. Postoperative adverse events, perioperative opioid consumption, and intraoperative hemodynamics were secondary endpoints.

Results

There was an absence of notable discrepancy in the baseline data observed between the two groups. The QoR-40 scores exhibited greater values in group K when compared to group C on the first day following the surgical procedure (160.91 ± 9.11 vs 151.47 ± 8.35, respectively; mean difference 9.44 [95 %CI: 5.78-13.11]; P < 0.01). Within 24 h of surgery, the VAS score of group K was lower at rest and during movement. (P < 0.05 for each). Group K had much lower rates of nausea and vomiting within 24 h of surgery. (P < 0.05 for each). Group K received significantly lower total doses of sufentanil and remifentanil than group C. (17.28 ± 2.59 vs 43.43 ± 3.52; 0.51 ± 0.15 vs 1.24 ± 0.24). The proportion of patients who used ephedrine in surgery was higher in group C than in group K (P < 0.05).

Conclusions

Esketamine-based opioid-sparing anesthesia strategy is feasible and enhanced recuperation following surgery by decreasing adverse effects associated with opioids and pain scores compared to an opioid-based anesthetic regimen.

Effective dose of propofol combined with intravenous esketamine for smooth flexible laryngeal mask airway insertion in two distinct age groups of preschool children

BACKGROUND

There is limited research on the combined use of propofol and esketamine for anesthesia induction during flexible laryngeal mask airway (FLMA) in pediatric patients, and the effective dosage of propofol for FLMA smooth insertion remains unclear. We explored the effective dose of propofol combined with intravenous esketamine for the smooth insertion of FLMA in two distinct age groups of preschool children.

METHODS

This is a prospective, observer-blind, interventional clinical study. Based on age, preschool children scheduled for elective surgery were divided into group A (aged 1-3 years) and group B (aged 3-6 years). Anesthesia induction was started with intravenous administration of esketamine (1.0 mg.kg- 1) followed by propofol administration. The FLMA was inserted 2 min after propofol administration at the target dose. The initial dose of propofol in group A and group B was 3.0 mg.kg- 1 and 2.5 mg.kg- 1, respectively. The target dose of propofol was determined with Dixon's up-and-down method, and the dosing interval of propofol was 0.5 mg.kg- 1. If there was smooth insertion of FLMA in the previous patient, the target dose of propofol for the next patient was reduced by 0.5 mg.kg- 1; otherwise, it was increased by 0.5 mg.kg- 1. The median 50% effective dose (ED50) for propofol was estimated using Dixon's up-and-down method and Probit analysis, while the 95% effective dose (ED95) was estimated through Probit analysis. Vital signs and adverse events during induction were recorded.

RESULTS

Each group included 24 pediatric patients. Using Dixon's up-and-down method, the ED50 of propofol combined with esketamine for smooth insertion of FLMA in group A was 2.67 mg.kg- 1 (95%CI: 1.63-3.72), which was higher than that in group B (2.10 mg. kg- 1, 95%CI: 1.36-2.84) (p = 0.04). Using Probit analysis, the ED50 of propofol was calculated as 2.44 (95% CI: 1.02-3.15) mg.kg- 1 in group A and 1.93 (95% CI: 1.39-2.32) mg.kg- 1 in group B. The ED95 of propofol was 3.72 (95%CI: 3.07-15.18) mg.kg- 1 in group A and 2.74 (95%CI: 2.34-5.54) mg.kg- 1 in group B. In Group B, one pediatric patient experienced laryngospasm.

CONCLUSION

The effective dose of propofol when combined with intravenous esketamine for smooth insertion of FLMA in children aged 1-3 years is 2.67 mg.kg- 1, which is higher than that in children aged 3-6 years (2.10 mg. kg- 1).

TRIAL REGISTRATION

Chinese Clinical Trial Registry Center (Registration Number: ChiCTR2100044317; Registration Date: 2021/03/16).

Esketamine use is associated with shortened postoperative hospital stay in patients after knee arthroscopic surgery: a propensity score-matched cohort study

BACKGROUND

Previous studies have examined anesthetics to improve postoperative prognosis after knee arthroscopic surgery. However, it is currently unknown whether perioperative anesthetics can influence postoperative hospital stay. We investigated the impact of esketamine after knee arthroscopic surgery on post-operative length of stay, fever and surgical site infection.

METHODS

This study included 455 patients who underwent knee surgery between January2020 and August 2021at a tertiary hospital in China. Patient characteristics, preoperative laboratory values, intra-operative anesthetic data, and postoperative outcomes were collected. Univariate and multivariate logistic regression analyses with or without propensity score matching were performed to identify factors related to post-operative discharge within 3 days(PD3).

RESULTS

A total of 297 cases met our inclusion criteria. The mean age of patients was 42 ± 14 years, mean body mass index, 24.1 ± 3.5 kg/m2, 157(53%) patients were male. Meniscus-related procedures accounted for the most part of all the procedures with a percentage of 40.4%, followed by combined procedures of 35.4%. After we adjusted for demographic and intraoperative characteristics with propensity score matching, esketamine use was significantly associated with PD3 with the highest odds ratio of 2.28 (95% confidence interval (CI): 1.18-4.41, p = 0.014).

CONCLUSION

Esketamine use was associated with PD3 in patients underwent knee arthroscopic surgery. The findings of this study will be useful to anesthesiologists in making informed decisions regarding the choice of anesthetics for knee joint diseases.

TRIAL REGISTRATION

This study was approved by the Ethics Committee (Approval No.:2023-041-01) of the Eighth Affiliated Hospital, Sun Yat-sen University and retrospectively registered.

Effect of Esketamine Added to Propofol Sedation on Desaturation and Hypotension in Bidirectional Endoscopy: A Randomized Clinical Trial

Importance

Propofol sedation is widely used for endoscopic procedures, but it poses risks of hemodynamic and respiratory depression. The addition of esketamine as an adjuvant may reduce propofol requirements and associated adverse events.

Objective

To evaluate the effects of low-dose esketamine added to propofol-based sedation on desaturation and hypotension during same-visit bidirectional endoscopy.

Design, Setting, and Participants

This multicenter, double-blind, placebo-controlled randomized clinical trial assessed patients from 3 teaching hospitals in China who were scheduled for same-visit bidirectional endoscopy between February 8 and November 30, 2022, and randomly assigned to receive esketamine or normal saline (placebo).

Interventions

After induction of sedation with 0.1 μg/kg of sufentanil and 0.5 mg/kg of propofol, patients in the esketamine group received 0.15 mg/kg of intravenous esketamine, whereas patients in the placebo group received an equivalent volume of saline. Sedation was achieved through propofol titration.

Main Outcomes and Measures

The primary outcome was the composite of desaturation and hypotension during the procedures. Secondary outcomes included desaturation, hypotension, propofol requirements, postprocedure pain and fatigue, nausea or vomiting, dizziness or headache, hallucination or nightmare, endoscopist satisfaction, and patient satisfaction.

Results

Among the 663 initially enrolled patients, 660 completed the study (median [IQR] age, 48 [36-57] years; 355 [53.8%] female), with 331 randomized to the esketamine group and 329 to the placebo group. The administration of esketamine compared with placebo significantly reduced the incidence of the composite outcome of desaturation and hypotension (8.2% vs 21.0%; difference, -12.8 percentage points; odds ratio [OR], 0.34; 95% CI, 0.21-0.54; P < .001). Additionally, esketamine led to significantly lower incidences of desaturation (OR, 0.36; 95% CI, 0.18-0.72; false discovery rate q = .01) and hypotension (OR, 0.33; 95% CI, 0.18-0.60; q < .001) and reduced propofol requirements (difference, -58.9 mg; 95% CI, -65.7 to -52.2 mg; q < .001), without significant effects on other secondary outcomes.

Conclusions and Relevance

In this randomized clinical trial of patients undergoing same-visit bidirectional endoscopy, the administration of low-dose esketamine resulted in an approximately 61% reduction in the incidence of desaturation and hypotension, accompanied by decreased propofol requirements. These findings support the use of esketamine as an adjuvant to propofol-based sedation in endoscopic procedures.

Trial Registration

Chinese Clinical Trial Registry Identifier: ChiCTR2200055938.

Safety and tolerability of esketamine in propofol based sedation for endoscopic variceal ligation with or without injection sclerotherapy: Randomized controlled trial

OBJECTIVES

Esketamine is an S (+) enantiomer of ketamine with greater potency and similar psychomimetic effects compared to racemic ketamine. We aimed to explore the safety of esketamine in different doses as an adjuvant to propofol in patients undergoing endoscopic variceal ligation (EVL) with or without injection sclerotherapy.

METHODS

One hundred patients were randomized to receive sedation with propofol 1.5 mg/kg in combination with sufentanil 0.1 μg/kg (group S), esketamine 0.2 mg/kg (group E0.2), esketamine 0.3 mg/kg (group E0.3), or esketamine 0.4 mg/kg (group E0.4) for EVL (n = 25 each). Hemodynamic and respiratory parameters were recorded during the procedure. The primary outcome was the incidence of hypotension; secondary outcomes included the incidence of desaturation, positive and negative syndrome scale (PANSS) after the procedure, pain score after the procedure, and secretion volume.

RESULTS

The incidence of hypotension was significantly lower in groups E0.2 (36%), E0.3 (20%), and E0.4 (24%) than in group S (72%). The incidence of SpO2  ≤94% was significantly lower in group E0.4 (4%) than in group S (32%). No significant intergroup difference was found in the PANSS assessment.

CONCLUSIONS

Combining 0.4 mg/kg esketamine with propofol sedation was optimal to facilitate EVL with stable hemodynamic status and better respiratory function during the procedure, without significant psychomimetic side-effects.

TRIAL REGISTRATION

Chinese Clinical Trial Registry (Trial ID: ChiCTR2100047033, http://www.chictr.org.cn/showproj.aspx?proj=127518).

Recent advances in the study of anesthesia-and analgesia-related mechanisms of S-ketamine

Ketamine is a racemic mixture of equal amounts of R-ketamine and S-ketamine and is well known to anesthesiologists for its unique dissociative anesthetic properties. The pharmacological properties of ketamine, namely, its sympathetic excitation, mild respiratory depression, and potent analgesia, are still highly valued in its use as an anesthetic for some patients. In particular, since its advent, S-ketamine has been widely used as an anesthetic in many countries due to its increased affinity for NMDA receptors and its enhanced anesthetic and analgesic effects. However, the anesthetic and analgesic mechanisms of S-ketamine are not fully understood. In addition to antagonizing NMDA receptors, a variety of other receptors or channels may be involved, but there are no relevant mechanistic summaries in the literature. Therefore, the purpose of this paper is to review the mechanisms of action of S-ketamine on relevant receptors and systems in the body that result in its pharmacological properties, such as anesthesia and analgesia, with the aim of providing a reference for its clinical applications and research.

Median effective dose (ED50) of esketamine combined with propofol for children to inhibit response of gastroscope insertion

BACKGROUND

Propofol is the most commonly used drug for procedural sedation during gastroscopy. However, independent use of propofol can lead to increased dosage and additional side effects. Esketamine was found to be exceptional in combination with propofol for painless gastroscopy. No studies have calculated the median effective dose (ED₅₀) of esketamine combined with propofol in pediatric painless gastroscopy. Here, we designed a research to study the ED₅₀ of esketamine combined with propofol using the Dixon and Massey up-and-down sequential method for inhibiting the response of gastroscope insertion.

METHODS

Children who met the inclusion and exclusion criteria were included in this study. Propofol and esketamine were used as anesthetics for painless gastroscopy in children. To explore the ED₅₀, the initial propofol dose was set at 3 mg/kg in all children. The first child was given an esketamine dose of 0.1 mg/kg, followed by 30 s of slow bolus injection propofol. If anesthesia induction failed (coughing or body movement of children during gastroscope insertion), the esketamine dose was elevated in the next child, with a interval difference of 0.05 mg/kg. Otherwise, if the anesthesia induction was successful, the next dosage was reduced by 0.05 mg/kg. The study was stopped if nine crossover inflection points were reached. The ED₅₀ of esketamine was calculated using probit regression, and the blood pressure, pulse oxygen saturation, heart rate, recovery time, and side effects were recorded in all children.

RESULTS

A total of 26 children were included in this study. The ED₅₀ of esketamine combined with 3 mg/kg propofol was 0.143 mg/kg (95% CI 0.047-0.398 mg/kg). The total consumption of propofol was 16.04 ± 5.37 mg. The recovery time was 16.38 ± 8.70 min. Adverse effects recorded were delayed awakening in two cases and increased oral secretions of another child during the examination inducing cough and hypoxemia (86% was the lowest).

DISCUSSION

The ED₅₀ of esketamine was 0.143 mg/kg when combined with 3 mg/kg propofol for successful sedation in pediatric gastroscope insertion. This sub-anaesthetic dose of esketamine was safe and efficacious with few complications in pediatric painless gastroscopy.

TRIAL REGISTRATION

The study was registered at the Chinese Clinical Trial Registry ( www.chictr.org.cn ; registration number: ChiCTR2100052830 on 06/11/2021).

Pharmacology of viable mechanism agnostic respiratory stimulants for the reversal of drug-induced respiratory depression in humans

INTRODUCTION

Drug-induced respiratory depression is potentially fatal and can be caused by various drugs such as synthetic opioids and tranquilizers. The only class of respiratory depressants that has a specific reversal agent are opioids, such as naloxone. These reversal agents have limited utility in situations of polysubstance ingestion with agents from multiple respiratory depressant classes. Hence, there is an unmet need for drugs that stimulate breathing irrespective of the underlying cause of respiratory depression, i.e. mechanism agnostic respiratory stimulants.

AREAS COVERED

In this review, we discuss agnostic respiratory stimulants, tested in humans with promising results, i.e. ampakines, drugs that act at the carotid bodies, N-methyl-D-aspartate receptor antagonist ketamine, and orexin receptor-2-agonist danavorexton, and others that demonstrated positive effects in animals but not yet in humans.

EXPERT OPINION

Rapid, effective rescuing of individuals who overdosed on respiratory depressants saves lives. While naloxone is the preferred drug for reversing opioid-induced respiratory depression, its effectiveness is limited in cases involving non-opioids. While several agnostic respiratory stimulants showed promise in humans, further research is needed to optimize dosing, evaluate safety and efficacy in deeper respiratory depression (apnea). Additionally, future studies should combine agnostic stimulants with naloxone, to improve rapid, effective rescue from drug overdoses.

Intraoperative intravenous low-dose esketamine improves quality of early recovery after laparoscopic radical resection of colorectal cancer: A prospective, randomized controlled trial

BACKGROUND

Esketamine has higher potency, stronger receptor affinity, a stronger analgesic effect, a higher in vivo clearance rate, and a lower incidence of adverse reactions when compared to ketamine. However, there have been few ketamine studies to assess patient-centered, overall recovery outcomes from the perspective of patients with colorectal cancer.

METHODS

This was a prospective, randomized controlled trial. Ninety-two patients undergoing laparoscopic radical resection of colorectal cancer were randomly assigned to either the esketamine (K group) or non-eskatamine (C group) group. After anesthesia induction, a loading dose of 0.25 mg/kg was administered, followed by continuous infusion at a rate of 0.12 mg.kg-1.h-1 until closure of surgical incisions in the K group. In the C group, an equivalent volume of normal saline was infused. The primary outcome was quality of recovery at 24 h after surgery, as measured by the Quality of Recovery-15 (QoR-15) scale. The QoR-15 was evaluated at three timepoints: before (Tbefore), 24 h (T24h) and 72 h (T72h) after surgery.

MAIN RESULTS

A total of 88 patients completed this study. The total QoR-15 scores in K group (n = 45) were higher than in the C group (n = 43) at 24 h: 112.33 ± 8.79 vs. 103.93 ± 9.03 (P = 0.000) and at 72 h: 118.73 ± 7.82 vs. 114.79 ± 7.98 (P = 0.022). However, the differences between the two groups only had clinical significance at 24 h after surgery. Among the five dimensions of the QoR-15, physical comfort (P = 0.003), emotional state (P = 0.000), and physical independence (P = 0.000) were significantly higher at 24 h in the K group, and physical comfort (P = 0.048) was higher at 72 h in the K group.

CONCLUSIONS

This study found that intraoperative intravenous low-dose esketamine could improve the early postoperative quality of recovery in patients undergoing laparoscopic radical resection of colorectal cancer from the perspective of patients.

Evaluating efficacy and safety of sub-anesthetic dose esketamine as an adjuvant to propofol/remifentanil analgosedation and spontaneous respiration for children flexible fibreoptic bronchoscopy: a prospective, double-blinded, randomized, and placebo-controlled clinical trial

Background: Flexible fiberoptic bronchoscopy (FFB) for children is widely performed under sedation. Currently, the optimal sedation regimen remains unclear. Esketamine is an N-methyl-D-aspartic acid (NMDA) receptor antagonist, which has stronger sedative and analgesic effects and exerts less cardiorespiratory depression than other sedatives. The purpose of this study was to evaluate whether a subanesthetic dose of esketamine as an adjuvant to propofol/remifentanil and spontaneous ventilation compared with control reduces the procedural and anesthesia-related complications of FFB in children. Materials and methods: Seventy-two children ≤ 12 years of age who were scheduled for FFB were randomly assigned, in a 1:1 ratio, to the esketamine-propofol/remifentanil (Group S, n = 36) or to the propofol/remifentanil group (Group C, n = 36). All children were retained spontaneous ventilation. The primary outcome was the incidence of oxygen desaturation (respiratory depression). Perioperative hemodynamic variables, blood oxygen saturation (SPO₂), end-tidal partial pressure of carbon dioxide (PetCO₂), respiratory rate (R), and the Bispectral index (BIS), induction time, procedural time, recovery time, the time to the ward from the recovery room, consumption of propofol and remifentanil during the procedure and the appearance of adverse events, including paradoxical agitation following midazolam administration, injection pain, laryngospasm, bronchospasm, PONV, vertigo, and hallucination were also compared. Results: The incidence of oxygen desaturation was significantly lower in Group S (8.3%) compared to Group C (36.1%, p = 0.005). The perioperative hemodynamic profile including SBP, DBP, and HR were more stable in Group S than that in Group C (p < 0.05). Consumption of propofol and remifentanil was lower in Group S than in Group C (p < 0.05). Furthermore, PAED scores, cough scores and injection pain were lower in the Group S than in Group C (p < 0.05). The recovery time of Group S was slightly longer than that of Group C (p < 0.05). Nobody happened paradoxical agitation following midazolam administration, PONV, vertigo, and hallucinations in both groups (p > 0.05). Conclusion: Our findings indicate that a subanesthetic dose of esketamine as an adjuvant to propofol/remifentanil and spontaneous respiration is an effective regimen for children undergoing FFB. Our findings will provide a reference for clinical sedation practice during these procedures in children. Clinical Trail Registration: Chinese clinicaltrials.gov registry (identifier: ChiCTR2100053302).

Efficacy and Safety of a Subanesthetic Dose of Esketamine Combined with Propofol in Patients with Obesity Undergoing Painless Gastroscopy: A Prospective, Double-Blind, Randomized Controlled Trial

Purpose

Patients with obesity are more susceptible to hypoxemia. Anesthetic management for patients with obesity undergoing painless gastroscopy presents a severe challenge for anesthesiologists. Esketamine is a NMDA antagonist that has been proven to be beneficial for ameliorating respiratory depression owing to its sympathomimetic effect; however, there are no relevant reports on its use in patients with obesity. We designed a randomized controlled trial to evaluate whether esketamine can be the ideal adjuvant to propofol sedation in patients with obesity undergoing painless gastroscopy.

Patients and Methods

A total of 104 patients with obesity undergoing painless gastroscopy were randomly divided into group C (propofol+saline) and group S (propofol+esketamine 0.25 mg/kg). Anesthesia was induced by 2 mg/kg propofol with saline or esketamine. The consumption of propofol, hemodynamic parameters, duration of procedure, induction time, postoperative awakening time, and orientation recovery time were recorded. Adverse events and satisfaction scores were also recorded.

Results

Propofol consumption was 274.4±22.6 mg and 201.3±16.6 mg in groups C and S, respectively. The induction time of groups C and S were 25.4±2.3 s and 17.8±1.9 s, respectively. The postoperative awakening times of groups C and S were 6.2±1.1 min and 4.8±1.3 min, respectively. Hemodynamic parameters were more stable in group S than in group C. The incidence of adverse events such as injection pain, hypoxemia, hypotension, bradycardia, choking, and body movement were significantly lower in group S. The satisfaction scores of the endoscopist and anesthesiologist were (4.58±0.49 vs 3.71±0.83) and (4.75±0.44 vs 3.33±0.92), respectively.

Conclusion

The combination of propofol and esketamine (0.25 mg/kg) improves the safety and reduces the incidence of adverse events in patients with obesity during painless gastroscopy. Thus, this method is worthy of clinical application.

Clinical Trials Registration

ChiCTR 2200062547.

Inhaled Δ9-tetrahydrocannabinol does not enhance oxycodone-induced respiratory depression: randomised controlled trial in healthy volunteers

BACKGROUND

In humans, the effect of cannabis on ventilatory control is poorly studied, and consequently, the effect of Δ⁹-tetrahydrocannabinol (THC) remains unknown, particularly when THC is combined with an opioid. We studied the effect of THC on breathing without and with oxycodone pretreatment. We hypothesised that THC causes respiratory depression, which is amplified when THC and oxycodone are combined.

METHODS

In this randomised controlled crossover trial, healthy volunteers were administered inhaled Bedrocan® 100 mg (Bedrocan International B.V., Veendam, The Netherlands), a pharmaceutical-grade high-THC cannabis variant (21.8% THC; 0.1% cannabidiol), after placebo or oral oxycodone 20 mg pretreatment; THC was inhaled 1.5 and 4.5 h after placebo or oxycodone intake. The primary endpoint was isohypercapnic ventilation at an end-tidal Pco₂ of 55 mm Hg or 7.3 kPa (V_E55), measured at 1-h intervals for 7 h after placebo/oxycodone intake.

RESULTS

In 18 volunteers (age 22 yr [3]; 9 [50%] female), oxycodone produced a 30% decrease in V_E55, whereas placebo was without effect on V_E55. The first cannabis inhalation resulted in V_E55 changing from 20.3 (3.1) to 23.8 (2.4) L min^-1 (P=0.06) after placebo, and from 11.8 (2.8) to 13.0 (3.9) L min^-1 (P=0.83) after oxycodone. The second cannabis inhalation also had no effect on V_E55, but slightly increased sedation.

CONCLUSIONS

In humans, THC has no effect on ventilatory control after placebo or oxycodone pretreatment.

CLINICAL TRIAL REGISTRATION

2021-000083-29 (EU Clinical Trials Register.).

The Use of Caffeine Citrate for Respiratory Stimulation in Acquired Central Hypoventilation Syndrome: A Case Series

Introductions

Caffeine is commonly used as a respiratory stimulant for the treatment of apnea of prematurity in neonates. However, there are no reports to date of caffeine used to improve respiratory drive in adult patients with acquired central hypoventilation syndrome (ACHS).

Presentation of case series

We report two cases of ACHS who were successfully liberated from mechanical ventilation after caffeine use, without side effects. The first case was a 41-year-old ethnic Chinese male, diagnosed with high-grade astrocytoma in the right hemi-pons, intubated and admitted to the intensive care unit (ICU) in view of central hypercapnia with intermittent apneic episodes. Oral caffeine citrate (1600mg loading followed by 800mg once daily) was initiated. His ventilator support was weaned successfully after 12 days. The second case was a 65-year-old ethnic Indian female, diagnosed with posterior circulation stroke. She underwent posterior fossa decompressive craniectomy and insertion of an extra-ventricular drain. Post-operatively, she was admitted to the ICU and absence of spontaneous breath was observed for 24 hours. Oral caffeine citrate (300mg twice daily) was initiated and she regained spontaneous breath after 2 days of treatment. She was extubated and discharged from the ICU.

Conclusion

Oral caffeine was an effective respiratory stimulant in the above patients with ACHS. Larger randomized controlled studies are needed to determine its efficacy in the treatment of ACHS in adult patients.

Low-dose esketamine for the prevention of emergency agitation in children after tonsillectomy: A randomized controlled study

Background: Emergency agitation is a common postoperative complication in pediatric patients after general anesthesia. The aim of this study was to explore the effects of a low dose of esketamine on emergency agitation in children following tonsillectomy. Materials and Methods: Eighty children were recruited prospectively to this study and divided into the esketamine group and the control group (40 cases in each group). The induction and maintenance of anesthesia were the same in both groups. At the end of surgery, the esketamine group received 0.25 μg/kg esketamine, while the control group received the same volume of normal saline. The extubation time, time to eye opening, Ramsay sedation scale and time to discharge from the post-anesthesia care unit (PACU) were recorded during post-anesthesia care unit. Postoperative complications, such as emergency agitation, respiratory depression, hypertension, tachycardia, nightmares, nausea, and vomiting, were also recorded. Results: The incidence of emergency agitation was lower in the esketamine group compared with that in the control group (5% vs. 27.5%, p = 0.006). The time to eye opening was longer in the esketamine group than in the control group (17.2 ± 2.7 vs. 15.5 ± 2.3 min, p = 0.005). However, the extubation time and time to discharge from PACU were similar between the two groups. Conclusion: Low-dose of esketamine decreases the incidence of emergency agitation in children after tonsillectomy without delaying extubation time and increasing the postoperative side effects. (www.chictr.org.cn, registration number: ChiCTR2100054178).

Esketamine-A quick-acting novel antidepressant without the disadvantages of ketamine

Esketamine, which is an S-enantiomer of ketamine, is better than conventional antidepressants and even better than R-ketamine. This article discusses the mechanism of action of Esketamine, how different it is from other antidepressants, its side effect profile, indications for use, various routes of administration and the review of existing literature on Esketamine.

Determining the effective dose of esketamine for mitigating pain during propofol injection by Dixon's up-and-down method: a double-blind, prospective clinical study of drug dose response

BACKGROUND

Propofol is an intravenous (IV) anesthetic medication widely used for procedural sedation, operative anesthesia, and in intensive care unit (ICU), but the incidence of pain during IV infusion can reach 28-90%. Ketamine can attenuate pain associated with IV propofol injection through local and central analgesic effects. Ketamine is gradually being transitioned to its S-enantiomer, esketamine, which has a similar mechanism of action. The purpose of our study is to determine the half effective dose (ED₅₀), 95% effective dose (ED₉₅), and 99% effective dose (ED₉₉) of esketamine for attenuating propofol injection pain using Dixon's up-and-down method to provide a reference for optimal dose selection for surgeries and procedures.

METHODS

Thirty gynecological patients undergoing hysteroscopic surgery were enrolled in a sequential method to determine the effective dose of esticketamine for analgesic propofol injection in order of operation. This study was based on the sequential allocation up-and-down rule designed by Dixon, and each patient was induced by esticketamine combined with propofol. During induction, the target dose of esketamine was first given via venous access in the left hand of the patient, and 30 s later, a fixed dose of 2 mg/kg (1 ml/s) of propofol was given. Patient perception of pain was scored with the verbal rating scale (VRS) every 5 s after the start of the propofol infusion, and the evaluation was stopped once the patient became unresponsive. The dosage of esketamine was increased or decreased up or down according to the patient's pain response. The initial dose of esketamine was 0.2 mg/kg, and the gradient of adjacent dose was 0.02 mg/kg. If the pain response assessment of the upper patient was positive (+), the dose of esselketamine in the next patient was increased by 0.02 mg/kg; if the pain response assessment of the upper patient was negative (-), the dose of esselketamine in the next patient was decreased by 0.02 mg/kg. The tests were carried out sequentially, with the pain response changing from positive to negative or from negative to positive, and the tests were stopped after at least 6 crossover points, and the effective dose of esticketamine was calculated using probit probability regression analysis.

RESULTS

The ineffective group comprised patients with a positive pain response and the effective group comprised patients with a negative pain response. The 95% CI was set as the confidence interval of effective dose ED value，and we found esketamine's ED₅₀ = 0.143 mg/kg (0.120, 0.162 mg/kg), ED₉₅ = 0.176 mg/kg (0.159, 0.320 mg/kg), and ED₉₉ = 0.189 mg/kg (0.167, 0.394 mg/kg). The esketamine dose and VRS score during propofol injection were significantly different between the two groups (P < 0.05), whereas surgical duration, emergence time, visual analogue scale (VAS) score of postoperative uterine contraction pain, and Riker sedation/anxiety scale (SAS) score were not significantly different. Bradycardia occurred in only one patient during anesthesia induction, while hemodynamics was stable in the rest of the patients without obvious adverse reactions.

CONCLUSION

Small doses of esketamine combined with propofol can be safely and effectively used for hysteroscopic surgery. We recommended a dose of 0.2 mg/kg IV esketamine before induction of anesthesia to reduce the pain of propofol injection.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2100048951. Date of registration: July 19, 2021.

Effect of esketamine vs dexmedetomidine adjunct to propofol sedation for pediatric 3Tesla magnetic resonance imaging: a randomized, double-blind, controlled trial

BACKGROUND

Adequate sedation is essential for pediatric patients undergoing 3Tesla (T) magnetic resonance imaging (MRI). Using propofol alone is associated with patient arousing and adverse airway events. This study aimed to assess esketamine vs dexmedetomidine adjunct to propofol sedation for pediatric 3 T MRI.

METHODS

In this randomized, double-blind, controlled trial, 114 pediatric patients aged between 6 months and 8 years were randomly assigned, in a 1:1 ratio, to the esketamine-propofol group or the dexmedetomidine-propofol group. Sedation was provided with esketamine or dexmedetomidine in combination with propofol titration. The primary outcome was the total dose of propofol. Secondary outcomes included propofol infusion dose, adverse events, time to emergence from sedation, and time to discharge from recovery room.

RESULTS

A total of 111 patients completed this study (56 in the esketamine-propofol group and 55 in the dexmedetomidine-propofol group). All MRI procedures were successfully performed under sedation. The total median (IQR) dose of propofol was significantly lower in the esketamine-propofol group (159.8 [121.7, 245.2] μg/kg/min) than that in the dexmedetomidine-propofol group (219.3 [188.6, 314.8] μg/kg/min) (difference in medians [95% CI] =  - 66.9 [- 87.8 to - 43.0] μg/kg/min, P < 0.0001). The use of esketamine resulted in a lower dose of propofol for titration (difference in medians [95% CI] =  - 64.3 [- 75.9 to - 51.9] μg/kg/min), a shorter time to emergence (difference in means [95% CI] =  - 9.4 [- 11.4 to - 7.4] min), and a reduced time to recovery room discharge (difference in means [95% CI] =  - 10.1 [- 12.1 to - 8.2] min). In the dexmedetomidine-propofol group, 2 patients experienced upper airway obstruction and 6 patients had bradycardia. No episodes of oxygen desaturation or other adverse events were observed.

CONCLUSIONS

Although both regimens provided effective sedation for pediatric 3 T MRI, the esketamine-propofol sedation reduced propofol requirement and facilitated recovery, without detection of increased adverse effects in the studied population. Trial registration Chinese Clinical Trial Registry (identifier: ChiCTR2100048477).

L-cysteine methyl ester overcomes the deleterious effects of morphine on ventilatory parameters and arterial blood-gas chemistry in unanesthetized rats

We are developing a series of thiolesters that produce an immediate and sustained reversal of the deleterious effects of opioids, such as morphine and fentanyl, on ventilation without diminishing the antinociceptive effects of these opioids. We report here the effects of systemic injections of L-cysteine methyl ester (L-CYSme) on morphine-induced changes in ventilatory parameters, arterial-blood gas (ABG) chemistry (pH, pCO₂, pO₂, sO₂), Alveolar-arterial (A-a) gradient (i.e., the index of alveolar gas-exchange within the lungs), and antinociception in unanesthetized Sprague Dawley rats. The administration of morphine (10 mg/kg, IV) produced a series of deleterious effects on ventilatory parameters, including sustained decreases in tidal volume, minute ventilation, inspiratory drive and peak inspiratory flow that were accompanied by a sustained increase in end inspiratory pause. A single injection of L-CYSme (500 μmol/kg, IV) produced a rapid and long-lasting reversal of the deleterious effects of morphine on ventilatory parameters, and a second injection of L-CYSme (500 μmol/kg, IV) elicited pronounced increases in ventilatory parameters, such as minute ventilation, to values well above pre-morphine levels. L-CYSme (250 or 500 μmol/kg, IV) also produced an immediate and sustained reversal of the deleterious effects of morphine (10 mg/kg, IV) on arterial blood pH, pCO₂, pO₂, sO₂ and A-a gradient, whereas L-cysteine (500 μmol/kg, IV) itself was inactive. L-CYSme (500 μmol/kg, IV) did not appear to modulate the sedative effects of morphine as measured by righting reflex times, but did diminish the duration, however, not the magnitude of the antinociceptive actions of morphine (5 or 10 mg/kg, IV) as determined in tail-flick latency and hindpaw-withdrawal latency assays. These findings provide evidence that L-CYSme can powerfully overcome the deleterious effects of morphine on breathing and gas-exchange in Sprague Dawley rats while not affecting the sedative or early stage antinociceptive effects of the opioid. The mechanisms by which L-CYSme interferes with the OR-induced signaling pathways that mediate the deleterious effects of morphine on ventilatory performance, and by which L-CYSme diminishes the late stage antinociceptive action of morphine remain to be determined.

Effect of different doses of esketamine compared with fentanyl combined with propofol on hypotension in patients undergoing painless abortion surgery: a prospective, randomized, double-blind controlled clinical trial

Background

Opioids analgesics commonly used in abortion procedures are associated with respiratory and circulatory depression. Esketamine is a N-methyl-D-aspartate receptor (NMDA) antagonist and a common analgesic. The drug has several advantages including rapid onset and offset and it causes minimal cardiorespiratory depression. However, studies have not explored the effects of esketamine in patients undergoing painless abortion surgery. Therefore, the present study sought to evaluate the effect of different doses of esketamine compared with the effect of fentanyl on incidence of perioperative hypotension in patients undergoing painless abortion surgery and to explore the optimal esketamine dose for this population.

Methods

A total of 178 female patients undergoing painless abortion surgery were enrolled to the current study. The patients were aged 18–45 years, had a body mass index (BMI) of 18–28 kg m^− 2 and a class I or II physical status as determined using the American Society of Anesthesiologists (ASA) system. Patients were randomly assigned to four groups as follows: group F (n = 45) in which patients underwent intravenous (IV) administration of 1 μg kg^− 1 fentanyl followed by IV administration of 2 mg kg^− 1 propofol, and group EL, group EM and group EH (n = 45, 44, 44) with patients receiving IV administration of 0.2 mg kg^− 1, 0.25 mg kg^− 1, 0.3 mg kg^− 1 esketamine, respectively, followed by IV administration of 2 mg kg^− 1 propofol. The primary outcome of the study was the incidence of hypotension whereas secondary outcomes included incidence of adverse events, perioperative changes of vital signs, anesthesia induction time, recovery time and dischargeable time, propofol addition, as well as patient, surgeon and anesthesiologist satisfaction levels.

Results

The findings showed that the incidence of hypotension was significantly lower in subjects in group EL, group EM and group EH (0, 0, 0%) relative to the incidence in patients in group F (20%) (χ² = 19.648; P = 0.000). In this study, the incidence of hypoxia of subjects in group EL, group EM and group EH (0, 2.3, 2.3%) was significantly lower compared with that of patients in group F (11.1%) (χ² = 8.622; P = 0.035). The findings indicated that the incidence of somatic motor reactions was significantly lower in participants in group EM and group EH (9.1, 4.5%) relative to that of patients in group F and group EL (26.7, 15.6%) (χ² = 10.254; P = 0.016). The results showed that the incidence of nausea and vomiting and potential psychiatric symptoms were significantly higher in patients in group EH (15.9, 11.4%) compared with that of participants in group F (2.2, 0%), group EL (4.4, 0%) and group EM (2.3, 2.3%) (χ² = 7.493; P = 0.038 and χ² = 8.248; P = 0.003). In this study, the mean arterial pressure (MAP) and heart rate (HR) of subjects in group EL, group EM and group EH were more stable compared with that of patients in group F. Frequency of the additional propofol dose was markedly less in group EM and EH (26.7%, 17,8%) compared with that in group F and EL (9.1, 4.5%) (χ² = 10.254; P = 0.016). The findings indicated that the dischargeable time was significantly shorter for patients in group EM compared with that of subjects in group F, group EL and group EH.

Conclusions

The findings of the present study showed that single-dose esketamine (0.25 mg kg^− 1) effectively decreased incidence of hypotension and total adverse events and reduced the frequency of additional propofol dose required for patients undergoing painless abortion with preservation of physician-patient satisfaction.

Suicidal behavior-advances in clinical and neurobiological research and improvement of prevention strategies

Suicide is the 14^th leading cause of death worldwide. It is responsible for 1%-5% of all mortality. This article highlights the latest developments in universal, selective, and indicated prevention strategies. Concerning universal suicide prevention, current research has shown that strategies such as restricting access to lethal means (e.g., control of analgesics and hot-spots for suicide by jumping) and school-based awareness programs are most efficacious. Regarding selective prevention, substantial progress can be expected in psychological screening methods for suicidal behavior. The measurement of implicit cognition proved to be more valid in predicting future suicide attempts than classic clinical assessment. Latest developments are smartphone-based interventions and real-time monitoring of suicidal behavior. Great effort has been made to establish valid neurobiological screening methods (e.g., genetic and epigenetic risk factors for suicide, hypothalamic-pituitary-adrenal axis) without yielding a major bre-akthrough. Potentially, multiple biomarkers rather than a single one are necessary to identify individuals at risk. With regard to indicated prevention in form of psychopharmacological treatment, recent pharmacoepidemiological studies and meta-analyses have supported a protective role of antidepressants, lithium, and clozapine. However, the data concerning a specific anti-suicidal effect of these drugs are currently not consistent. Promising results exist for ketamine in reducing suicidal ideation, independently of its antidepressant effect. Concerning psychotherapy, recent findings suggest that psychotherapeutic interventions specifically designed to prevent suicide re-attempts are most efficacious. Specifically, cognitive behavioral therapy and psychodynamic therapy approaches proved to decrease the number of suicide re-attempts significantly.

Opioid-free total intravenous anesthesia for thyroid and parathyroid surgery: Protocol for a randomized, double-blind, controlled trial

Background

Opioid-free anesthesia (OFA) may improve postoperative outcomes by reducing opioid-related adverse effects. This study aims to evaluate the effects of OFA on postoperative nausea and vomiting (PONV), postoperative pain, and 30-day outcomes after thyroid and parathyroid surgery.

Methods

This two-center, randomized, double-blind, controlled trial will include 400 adult patients scheduled for thyroid and parathyroid surgery. Patients will be randomly assigned, 1:1 and stratified by sex and site, to an OFA group (esketamine, lidocaine, and dexmedetomidine) or a control group (opioid-based anesthesia with sufentanil). All patients will receive propofol-based total intravenous anesthesia and PONV prophylaxis with dexamethasone and ondansetron. The primary outcome is the incidence of PONV (defined as experiencing any event of nausea, retching, or vomiting) during the first 48 h postoperatively. The secondary outcomes include the severity of PONV, antiemetic rescue therapy, pain scores at rest and while coughing, need for rescue analgesia, perioperative adverse effects related to anesthetics or analgesics (hypotension, bradycardia, hypertension, tachycardia, desaturation, dizziness, headache, hallucination, and nightmare), time to extubation, length of post-anesthesia care unit stay, length of postoperative hospital stay, patient satisfaction, and a composite of 30-day major adverse events (myocardial infarction, cardiac arrest, cerebrovascular accident, coma, acute renal failure, pulmonary embolism, sepsis, septic shock, deep neck space infection, reintubation, reoperation, blood transfusion, failure to wean off ventilator, and death). Analyses will be performed in the modified intention-to-treat population.

Discussion

We hypothesize that our OFA regimen reduces PONV after thyroid and parathyroid surgery. We will also investigate whether OFA leads to improvements in postoperative pain and major adverse events. Our results will offer evidence for optimizing anesthesia regimens in patients who undergo thyroid and parathyroid surgical procedures.

Clinical trial registration

http://www.chictr.org.cn, identifier: ChiCTR2200059656.

Comparison of the Effects of Esketamine/Propofol and Sufentanil/Propofol on the Incidence of Intraoperative Hypoxemia during Bronchoscopy: Protocol for a Randomized, Prospective, Parallel-Group Trial

BACKGROUND

Propofol, ketamine, and sufentanil are the most commonly used anesthetics during bronchoscopy, alone or in combination, for sedation. Esketamine is an s-enantiomer of ketamine racemate and has both sedative and analgesic effects. Esketamine does not inhibit respiration and maintains hemodynamic stability. This study aims to compare the clinical efficacy of esketamine/propofol with sufentanil/propofol for patients during bronchoscopy.

METHODS

Patients undergoing bronchoscopy will be randomly assigned to receive either sufentanil/propofol (sufentanil group; n = 33; sufentanil: 0.2 μg/kg) or esketamine/propofol (esketamine group; n = 33; esketamine: 0.2 mg/kg) for sedation and analgesia. Intraoperative clinical information, general anesthetic drug dosage, the incidence of intraoperative hypoxemia, total time of hypoxemia, awakening time, delirium, nausea and vomiting, adverse reactions, and patient satisfaction will be collected.

DISCUSSION

Hypoxia has detrimental effects on patients with respiratory disease. Ameliorating hypoxemia in patients undergoing bronchoscopy is critical. Our results will provide effective sedation with esketamine in patients undergoing bronchoscopy.

TRIAL REGISTRATION

Chinese clinical trial registry: ChiCTR2200058990.

Respiratory effects of the atypical tricyclic antidepressant tianeptine in human models of opioid-induced respiratory depression

BACKGROUND

Animal data suggest that the antidepressant and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor modulator tianeptine is able to prevent opioid-induced respiratory depression. We hypothesize that oral or intravenous tianeptine can effectively prevent or counteract opioid-induced respiratory depression in humans.

METHODS

Healthy male and female volunteers participated in two studies that had a randomized, double blind, placebo-controlled, crossover design. We first tested oral tianeptine (37.5, 50 and 100 mg, 8 subjects/group) pretreatment followed by induction of alfentanil-induced respiratory depression (alfentanil target concentration 100 ng/mL). Primary endpoint was ventilation at an extrapolated end-tidal carbon dioxide concentration of 55 mmHg (V̇E55). We next determined the ability of four subsequent and increasing infusions of intravenous tianeptine (target tianeptine plasma concentrations 400, 1,000, 1,500 and 2,000 ng/mL, each given over 15 min), to counteract remifentanil-induced respiratory depression in 15 volunteers. Ventilation was measured at isohypercpania (baseline ventilation 20 ± 2 L/min). Primary endpoint was minute ventilation during the 60 min of tianeptine versus placebo infusion.

RESULTS

Alfentanil reduced V̇E55 to 13.7 (95% CI 8.6-18.8) L/min following placebo pretreatment and to 17.9 (10.2-25.7) L/min following 50 mg tianeptine pretreatment (mean difference between treatments 4.2 (-11.5-3.0) L/min, p = 0.070). Intravenous tianeptine in the measured concentration range of 500 to 2,000 ng/ml did not stimulate ventilation but instead worsened remifentanil-induced respiratory depression: tianeptine 9.6 ± 0.8 L/min versus placebo 15.0 ± 0.9 L/min, mean difference 5.3 L/min, 95% CI 2.5-8.2 L/min; p = 0.001, after 1 hour of treatment.

CONCLUSIONS

Neither oral nor intravenous tianeptine were respiratory stimulants. Intravenous tianeptine over the concentration range of 500-2000 ng/mL worsened respiratory depression induced by remifentanil.

Are thyrotropin-releasing hormone (TRH) and analog taltirelin viable reversal agents of opioid-induced respiratory depression?

Opioid-induced respiratory depression (OIRD) is a potentially life-threatening complication of opioid consumption. Apart from naloxone, an opioid antagonist that has various disadvantages, a possible reversal strategy is treatment of OIRD with the hypothalamic hormone and neuromodulator thyrotropin-releasing hormone (TRH). In this review, we performed a search in electronic databases and retrieved 52 papers on the effect of TRH and TRH-analogs on respiration and their efficacy in the reversal of OIRD in awake and anesthetized mammals, including humans. Animal studies show that TRH and its analog taltirelin stimulate breathing via an effect at the preBötzinger complex, an important respiratory rhythm generator within the brainstem respiratory network. An additional respiratory excitatory effect may be related to TRH's analeptic effect. In awake and anesthetized rodents, TRH and taltirelin improved morphine- and sufentanil-induced respiratory depression, by causing rapid shallow breathing. This pattern of breathing increases the work of breathing, dead space ventilation, atelectasis, and hypoxia. In awake and anesthetized humans, a continuous infusion of intravenous TRH with doses up to 8 mg, did not reverse sufentanil- or remifentanil-induced respiratory depression. This is related to poor penetration of TRH into the brain compartment but also other causes are discussed. No human data on taltirelin are available. In conclusion, data from animals and human indicate that TRH is not a viable reversal agent of OIRD in awake or anesthetized humans. Further human studies on the efficacy and safety of TRH's more potent and longer lasting analog taltirelin are needed as this agent seems to be a more promising reversal drug.

Low-Dose Esketamine as an Adjuvant to Propofol Sedation for Same-Visit Bidirectional Endoscopy: Protocol for a Multicenter Randomized Controlled Trial

Background

Same-visit bidirectional endoscopy (esophagogastroduodenoscopy and colonoscopy) is widely performed under sedation. At present, the optimal sedation regimen remains unclear. This study aims to test the hypothesis that a low-dose esketamine added to propofol sedation reduces hemodynamic and respiratory adverse events in these procedures.

Methods

In this multicenter, randomized, double-blind, placebo-controlled trial, 660 adult patients scheduled for same-visit bidirectional endoscopy under sedation from 3 teaching hospitals in China will be recruited. Patients will be randomly allocated, in a 1:1 ratio, to an esketamine group or a normal saline group (n = 330 in each group), stratified by study center. All patients will receive intravenous propofol 0.5 mg/kg and sufentanil 0.1 μg/mL for induction of sedation, followed by intravenous esketamine 0.15 mg/kg or the same volume of normal saline. Propofol will be titrated to the target sedation levels during the procedures. The primary endpoint is a composite of desaturation (peripheral oxygen saturation < 90%) and hypotension (systolic blood pressure <80 mmHg or decrease >30% of baseline). Secondary endpoints include desaturation, hypotension, total dose of propofol, pain scores and fatigue scores on the 0-10 numerical rating scale, dizziness or headache, hallucination or nightmare, nausea or vomiting, endoscopist satisfaction, and patient satisfaction. All analyses will be intention-to-treat.

Discussion

We expect that a low-dose esketamine adjunct to propofol-based sedation will improve cardiorespiratory stability in patients undergoing same-visit bidirectional endoscopy, providing reference for clinical sedation practice during these procedures.

Trial Registration

Chinese Clinical Trial Registry (Identifier: ChiCTR-ChiCTR2200055938).

Efficacy and Safety of Remimazolam Tosilate Combined With Esketamine for Analgesic Sedation in Mechanically Ventilated ICU Patients: A Single-Arm Clinical Study Protocol

Introduction

Patients in the intensive care unit (ICU) frequently experience increased heart rate, blood pressure, and respiration rate as a product of anxiety and restlessness about their condition and treatments. Analgesia and sedation commonly involve benzodiazepines or opioids that lead to respiratory suppression and other adverse reactions. Remimazolam tosilate is a short-acting GABAA receptor agonist with reduced cardiovascular and respiratory inhibition compared to other commonly used benzodiazepines. Esketamine is a non-competitive N-methyl-D-aspartic acid (NMDA) receptor inhibitor that inhibits hyperalgesia and prolongs postoperative analgesia. It also reduces postoperative pain, delirium, and the use and acute tolerance of opioids. This study aims to assess the efficacy and safety of remimazolam tosilate combined with esketamine and sufentanil for sedation and analgesia in mechanically ventilated ICU patients.

Methods and Analysis

This prospective, single-arm, single-center, open-label clinical trial will be conducted from January 2022 to December 2023. The study will include 200 adult patients (≥ 18 years) from Shandong Provincial Hospital (affiliated with Shandong First Medical University) who are mechanically ventilated and admitted to the ICU between 24 and 72 h from the time of ventilation and who are administered analgesia and sedatives. Patients will undergo arterial blood gas analysis before administration. Remimazolam tosilate (0.2 mg/kg) will be injected intravenously within 30 s, followed by continuous infusion at a rate of 0.1 to 0.3 mg/kg/h via micropump. Esketamine (0.25 mg/kg) will be injected intravenously and maintained at 0.15 mg/kg/h, while sufentanil will be maintained at the rate of 0.1 to 0.2 μg/kg/h. The primary study outcome is the overall time required to maintain sedation. Secondary outcomes will include the total dosage used to reach the target sedation level, total mechanical ventilation time, awakening time, length of hospital stay, and incidence of cardiorespiratory-related adverse events and delirium. Adverse events (AEs) will be reported regardless of their relationship to the experimental drugs. AEs associated with adverse drug reactions will be classified as “affirmative correlation,” “possible relevance,” and “unable to determine.” A paired t-test or Wilcoxon signed-rank test will be used to compare the changes of observed indexes before and after treatment. A P &lt; 0.05 will be considered statistically significant.

Ethics and Dissemination

This study was approved by the local ethics committee at Shandong Provincial Hospital affiliatied to Shandong First Medical University. The results of this trial will be disseminated in peer-reviewed journals and at scientific conferences.

Trial Registration

The trial is registered at the Chinese Clinical Trial Registry: ChiCTR2100053106; date of registration: 2021-11-10.

Research advances in the clinical application of esketamine

Esketamine is dextrorotatory ketamine, which is an enantiomer of ketamine. Compared with ketamine, it has the advantages of a fast metabolism, fewer side effects, and strong pharmacological effects, so it is more suitable for clinical use. Esketamine has a powerful analgesic effect and has little effect on breathing. It has a wide range of applications in the fields of pediatric anesthesia, conscious sedation anesthesia, and emergency analgesia. In addition, it is also used for pain that is difficult to relieve with conventional drugs and to prevent postoperative pain. Various routes of administration are also suitable for patients who need short-term analgesia and sedation. As a drug, esketamine inevitably brings some side effects when it is used clinically. In this article, by introducing the mechanism of action and pharmacological characteristics of esketamine, its clinical application is reviewed, and it provides a reference for the more reasonable and safe clinical application of esketamine.

Treatment of opioid overdose: current approaches and recent advances

BACKGROUND

The USA has recently entered the third decade of the opioid epidemic. Opioid overdose deaths reached a new record of over 74,000 in a 12-month period ending April 2021. Naloxone is the primary opioid overdose reversal agent, but concern has been raised that naloxone is not efficacious against the pervasive illicit high potency opioids (i.e., fentanyl and fentanyl analogs).

METHODS

This narrative review provides a brief overview of naloxone, including its history and pharmacology, and the evidence regarding naloxone efficacy against fentanyl and fentanyl analogs. We also highlight current advances in overdose treatments and technologies that have been tested in humans.

RESULTS AND CONCLUSIONS

The argument that naloxone is not efficacious against fentanyl and fentanyl analogs rests on case studies, retrospective analyses of community outbreaks, pharmacokinetics, and pharmacodynamics. No well-controlled studies have been conducted to test this argument, and the current literature provides limited evidence to suggest that naloxone is ineffective against fentanyl or fentanyl analog overdose. Rather a central concern for treating fentanyl/fentanyl analog overdose is the rapidity of overdose onset and the narrow window for treatment. It is also difficult to determine if other non-opioid substances are contributing to a drug overdose, for which naloxone is not an effective treatment. Alternative pharmacological approaches that are currently being studied in humans include other opioid receptor antagonists (e.g., nalmefene), respiratory stimulants, and buprenorphine. None of these approaches target polysubstance overdose and only one novel approach (a wearable naloxone delivery device) would address the narrow treatment window.

Advances in Reversal Strategies of Opioid-induced Respiratory Toxicity

Opioids may produce life-threatening respiratory depression and death from their actions at the opioid receptors within the brainstem respiratory neuronal network. Since there is an increasing number of conditions where the administration of the opioid receptor antagonist naloxone is inadequate or undesired, there is an increased interest in the development of novel reversal and prevention strategies aimed at providing efficacy close to that of the opioid receptor antagonist naloxone but with fewer of its drawbacks such as its short duration of action and lesser ability to reverse high-affinity opioids, such as carfentanil, or drug combinations. To give an overview of this highly relevant topic, the authors systematically discuss predominantly experimental pharmacotherapies, published in the last 5 yr, aimed at reversal of opioid-induced respiratory depression as alternatives to naloxone. The respiratory stimulants are discussed based on their characteristics and mechanism of action: nonopioid controlled substances (e.g., amphetamine, cannabinoids, ketamine), hormones (thyrotropin releasing hormone, oxytocin), nicotinic acetylcholine receptor agonists, ampakines, serotonin receptor agonists, antioxidants, miscellaneous peptides, potassium channel blockers acting at the carotid bodies (doxapram, ENA001), sequestration techniques (scrubber molecules, immunopharmacotherapy), and opioids (partial agonists/antagonists). The authors argue that none of these often still experimental therapies are sufficiently tested with respect to efficacy and safety, and many of the agents presented have a lesser efficacy at deeper levels of respiratory depression, i.e., inability to overcome apnea, or have ample side effects. The authors suggest development of reversal strategies that combine respiratory stimulants with naloxone. Furthermore, they encourage collaborations between research groups to expedite development of viable reversal strategies of potent synthetic opioid-induced respiratory depression.

Recreational ketamine-related deaths notified to the National Programme on Substance Abuse Deaths, England, 1997-2019

BACKGROUND

Ketamine is a phencyclidine derivative with dissociative anaesthetic properties. Increasing numbers of individuals in England take ketamine recreationally. Information on deaths arising from such use in England is presented.

METHODS

Cases were extracted on 31 January 2020 from the National Programme on Substance Abuse Deaths database, based on text searches of the cause of death, coroner's verdict and positive toxicology results for the terms 'ketamine' or 'norketamine'.

FINDINGS

During 1997-2005, there were <5 deaths p.a. in which ketamine was implicated. Numbers increased until 2009 (21), plateauing until 2016; thereafter, deaths have risen to about 30 p.a. Decedents' characteristics (N = 283): male 84.1%, mean age 31.2 (SD 10.0) years, employed 56.5%, drug use history 79.6% and living with others 60.3%. Ketamine was detected with other substances in most cases. Main (74.6%) underlying cause of death was accidental poisoning. Ketamine may have impaired judgement in other cases.

CONCLUSIONS

Although controlled, recreational ketamine use and related fatalities continue to increase. Consumers need to be more aware of the potentially fatal risks they face.

The median effective concentration of propofol with different doses of esketamine during gastrointestinal endoscopy in elderly patients: A randomized controlled trial

AIMS

Propofol may result in hypotension, bradycardia and loss of protective reflexes, especially in elderly patients, while esketamine, a N-methyl-D-aspartate receptor antagonist, has analgesic, anaesthetic and sympathomimetic properties and is known to cause less cardiorespiratory depression. We hypothesized that esketamine may reduce the median effective concentration (EC₅₀ ) of propofol and coadministration is less likely to produce hypotension during gastrointestinal endoscopy in elderly patients.

METHODS

Ninety elderly patients, aged 65-89 years, undergoing gastrointestinal endoscopy were randomly assigned into 3 groups: SK0 (control) group (0 mg/kg esketamine); SK0.25 group (0.25 mg/kg esketamine); and SK0.5 group (0.5 mg/kg esketamine). Anaesthesia was achieved by plasma target-controlled infusion of propofol with different bolus doses of esketamine. The EC₅₀ of propofol for gastrointestinal endoscopy was determined by using the up-and-down method of Dixon. The initial plasma target concentration is 2.5 μg/mL and the adjacent concentration gradient is 0.5 μg/mL. Cardiovascular variables were also measured.

RESULTS

Propofol EC₅₀ s and its 95% confidence interval for gastrointestinal endoscopy in elderly patients were 3.69 (2.59-4.78), 2.45 (1.85-3.05) and 1.71 (1.15-2.27) μg/mL in the SK0, SK0.25 and SK0.5 groups, respectively (P < .05). The average percent change from baseline mean arterial pressure was -19.7 (7.55), -15.2 (7.14) and -10.1 (6.73), in the SK0, SK0.25 and SK0.5 groups, respectively (P < .001).

CONCLUSION

Combination medication of propofol with esketamine reduced the propofol EC₅₀ during gastrointestinal endoscopy in elderly patients compared with administration of propofol without esketamine. Increasing doses of SK with propofol are less likely to produce hypotension with shorter recovery time.

Ready for a "breakthrough" with ketamine? A look at recent pharmacological insights!

PURPOSE OF REVIEW

To update pharmacological insights on ketamine integrating information from different disciplines for developing steps to "breakthrough" approaches in clinical challenges.

RECENT FINDINGS

Pharmacokinetic/pharmacodynamic (PK/PD) models have incorporated recirculation, ketamine metabolites, drug-drug interaction, and covariates such as age. Ketamine-induced relief from treatment-resistant depression has been explained by "disinhibition" of gamma-aminobutyric acid-ergic interneurons and synaptogenic mechanisms requiring neurotrophic signals. Neuroimaging/electroencephalographic investigations have shown an increase in gamma spectral power in healthy volunteers and patients with depression, but also opposite changes in functional network connectivity after subanesthetic ketamine. Volunteer data may not be transferable to clinical conditions. Altered states of consciousness induced by subanesthetic ketamine have been described by disruption of resisting-state functional networks and frontoparietal connectivity with preservation of multisensory and sensor-motor networks. This has been interpreted as a "disconnected consciousness".

SUMMARY

More precise PK/PD models may improve the ketamine use regimen. The findings from research on depression are an important discovery because ketamine's impact on neuronal plasticity and synaptogenesis in human brain disease has directly been documented. Psychic adverse effects with subanesthetic ketamine are related to a "disconnected consciousness". Overall, progress has been made, but the "breakthrough" still has to come.