Effects of Intraoperative Ketamine Versus Dexmedetomidine on Release of Inammatory Mediators in Laparoscopic Hysterectomy. Prospective Randomized Trial

Background: Surgery and anesthesia are sources of stress to the patients. Inammatory reactions to this stress have adverse effects on wound healing and remote organs in addition to long-term sequels e.g. adhesion formation. We compared the effects of dexmedetomidine and ketamine on perioperative level of serum inammatory biomarkers including tumor necrosis factor-α, interleukin-6, and C- reactive protein. Methods: We included Seventy-ve patients, aged 30-60, ASA I–II, and scheduled for laparoscopic hysterectomy. Patients were randomized to receive intraoperative ketamine (bolus dose 0.25 mg/kg then continuous infusion 250 µg/kg/h), dexmedetomidine (1µg/kg bolus dose then continuous infusion 0.5 µg/kg/h), or placebo. The primary outcome was to measure serum level of inammatory biomarkers. Hemodynamic parameters, Recovery time, and complications within 24 hours postoperative were recorded. Results: Whilst there was signicant increase in concentrations of inammatory biomarkers 6 and 24 h postoperative in all groups, there were signicant differences between ketamine and dexmedetomidine group as compared to control group with no signicant differences between ketamine and dexmedetomidine group. As regard hemodynamic parameters, there were signicant increase in ketamine group and decrease in dexmedetomidine group as compared to base line with no need for medical intervention. There was delayed recovery in ketamine group versus control and dexmedetomidine group (24.3 ± 6.4, 12.6 ± 2.0, 13.5 ± 3.3 min respectively; P < 0.001). More complications were reported in ketamine group but did not reach statistical signicance. Conclusion: Dexmedetomidine and ketamine are comparable as regards attenuation of perioperative inammatory response. However, dexmedetomidine has a favorable safety prole.

One of the strategies used to reduce systemic cytokine response is to use anesthetic or sub anesthetic dose of general anesthesia or opioid with potential anti-in ammatory effect [5].
Effect of ketamine on perioperative in ammatory response has been widely studied. Recently, dexmedetomidine has been suggested to have anti-in ammatory properties [6] as in vitro studies [7][8][9] and few human studies (patients in ICU) [10,11].
The aim of this study is to compare the effect of continuous intraoperative infusion of dexmedetomidine to ketamine on postoperative release of in ammatory biomarkers which include tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), and C-reactive protein (CRP) in patients undergoing laparoscopic hysterectomy. In addition, we evaluate the safety pro le of both drugs.
We hypothesized that dexmedetomidine could attenuate the in ammatory response to surgery and anesthesia. In addition, dexmedetomidine may have less adverse effects than ketamine.

Methods
This prospective randomized study was carried out from November 2019 to May 2020 in Tanta University Hospitals. The trial followed the CONSORT 2010 statement guidelines for conducting a randomized controlled trial.
Ethics approval and consent to participate: This study was approved by the University's Institutional Review Board (IRB0010038) and written informed consent was obtained from all subjects participating in the trial. The trial was registered prior to patient enrollment. Trial registration ( Classi cation I-II, and scheduled for elective laparoscopic hysterectomy were included in the study. The trial followed the CONSORT 2010 guidelines for conducting a randomized controlled trial.
Exclusion criteria: The exclusion criteria included patient refusal, severe respiratory or cardiac disorders, hepatic or renal insu ciency, allergy to any of the study drugs, body mass index >35 kg /m 2 , uncontrolled diabetes, and use of any drug that might affect the immunity as chemotherapy or hormonal treatment.

Sample size calculation:
Based on previous study [12], we hypothesized that attenuation in cytokine concentration would be at least 30% 6 h after intravenous dexmedetomidine infusion intraoperative. Therefore, twenty-one patients are required in each group at an alpha value of 0.05 and 90% power of the study. To overcome the dropped-out cases, 25 patients are included in each group.
Patients were randomized into three equal groups (25 patients each) using computer-generated random numbers concealed in sealed opaque envelopes indicating the group of assignment. In group C (control group), patients received general anesthesia (GA) only while in group K (ketamine group), received racemic ketamine, and those in group D (dexmedetomidine group) received dexmedetomidine.
In the preoperative preparatory room, an intravenous line was established; midazolam 2 mg intravenous was given to all patients. A venous blood sample was withdrawn to determine base line values of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), C-reactive protein (CRP) which were used as in ammatory biomarkers.
On arrival to the operating theater, monitoring was applied to all participants including electrocardiogram (ECG), non-invasive blood pressure (NIBP) and pulse oximetry (Cardiocaps/5; DatexOhmeda, Helsinki, Finland). Baseline values of heart rate (HR) and mean arterial pressure (MAP) were recorded.
For all patients, GA was induced with fentanyl 1µg /kg, propofol 2mg/kg and cisatracurium 0.15 mg/kg. After endotracheal intubation, capnography was added to the previous monitoring. Patients in group K received racemic ketamine 0.25 mg/kg as intravenous bolus dose over 10 min then intravenous infusion at rate of 250 µg · kg -1 · h -1 While patients in group D received dexmedetomidine 1 µg/kg as intravenous bolus dose over 10 min then intravenous infusion at rate of 0.5 µg · kg -1 · h -1 .
Bolus dose of either drugs was given before the skin incision followed by continuous infusion according to the group of assignment. Anesthesia was maintained by iso urane 1.5-2% in 50% oxygen and cisatracurium 0.03mg/kg as required, and ventilator settings were adjusted to keep EtCO 2 between 35 and 40 mmHg.
After completion of the surgical procedure, ondansetron 4 mg intravenous was given and tracheal extubation was done after reversal of neuromuscular block and ful llment of extubation criteria.
All patients were transferred to the post-anesthesia care unit (PACU) and they were transferred to surgical ward according to modi ed Aldrete score (if score is ≥9) Our primary outcome was to assess in ammatory biomarkers TNF-α, IL-6, CRP at the following points: T1; base line before induction of anesthesia, T2; 6 hours after injection of the study drugs, T3; 24 hours after injection of the study drugs.
Venous blood samples were collected in into EDTA tubes. Blood samples from each subject were collected simultaneously over 10-20 minutes. Samples were immediately placed on ice and centrifuged at 2000 g for 10 minutes and then plasma was frozen and stored at −70C° until further analyzes which were performed within 10 days after collection. The sandwich ELISA (enzyme-linked immunosorbent assay) method using commercially available tests (Quantikine ELISA Kit, R&D Systems, Minneapolis, USA) was applied for determination of TNF-α, IL-6, CRP levels. The absorbance measurements were performed with a use of the photometer for microplates Elx 800 by Bio-Tek Instruments (USA). The absorbance values were read for the wavelength of λ = 450 nm with Λ correction 540 or 570 nm. The absorbance was converted into concentration units based upon a standard curve.
Secondary measurements were MAP and HR, which were measured at the following points: baseline before induction of anesthesia (T0), immediately after intubation (T1), immediately after end of bolus dose of the study drugs (T2), then every 10 min until the end of surgery. Recovery time was measured from discontinuation of anesthesia and reversal of muscle relaxant until transfer to PACU. Any adverse effects like postoperative nausea and vomiting (PONV), Hypotension (MAP < 65 mmHg), bradycardia (HR< 50 beat/min), over-sedation, and psychomimetic change as agitation, hallucinations, or vivid dreams up to 24 h after the surgery) were recorded.

Statistical analysis
Data were fed to the computer and analyzed using IBM SPSS software package version 20.0. (Armonk, NY: IBM Corp). The Kolmogorov-Smirnov test was used to verify the normality of distribution of variables; Comparisons between groups for categorical variables were assessed using Chi-square test (Fisher or Monte Carlo). ANOVA was used to compare more than two groups for normally distributed quantitative variables and followed by Post Hoc test (Tukey) for pairwise comparison. ANOVA with repeated measures and Post Hoc test (adjusted Bonferroni) was assessed for comparison between different periods Signi cance of the obtained results was judged at the 5% level.

Results
Over the duration of six months, 83 patients were assessed for eligibility but only 75 patients were chosen for the analysis. Three patients did not meet inclusion criteria and ve patients refused to participate in the study. Fortunately, no patients were lost during the follow up. The patients were randomly allocated in one of the three groups. Finally, 25 patients in each group were analyzed as shown in CONSORT ow diagram Fig. 1.
The study groups were comparable as regard to age, body mass index, and duration of the surgery [ Table 1].
Whilst there were signi cant increase in the concentrations of in ammatory biomarkers (TNF-α, IL-6, and CRP) 6 and 24 h postoperative in the 3 studied groups, there were signi cant differences between ketamine group and dexmedetomidine group as compared to the control group with no signi cant differences between ketamine group and dexmedetomidine group. The results indicated that ketamine and dexmedetomidine could attenuate the early postoperative in ammatory response [ Table 2].
It has been found that hemodynamic parameters (HR and MAP) were signi cantly increased as compared to the baseline values in ketamine group while in dexmedetomidine group; hemodynamic parameters were signi cantly decreased as compared to the baseline values. The patients were clinically stable and did not need any intervention. The overall measurement results are summarized in Figs. 3 and 4.
The results showed that there were no signi cant differences between the studied group as regard the adverse effects. More adverse effects reported in the ketamine group (agitation in one patient, nausea in six patients, vomiting in two patients). Although it was statistically non-signi cant, it is of clinical importance [ Table 3].
Availability of data and materials: The datasets used and / or analyzed during the current study are available from the corresponding author on reasonable request.

Discussion
Dexmedetomidine is an alpha 2 -adrenergic agonist, which has an analgesic, sedative, and sympatholytic effect. In addition, animal studies demonstrated the anti-in ammatory effect of dexmedetomidine [9,13].
Up to our knowledge, it is the rst study to compare the effect of dexmedetomidine and ketamine on suppression of in ammatory response (release of in ammatory biomarkers, including TNF-α, IL-6, and CRP) in female patients undergoing laparoscopic hysterectomy. In addition, we assessed the side effects of both drugs.
The choice of TNF-α and IL-6 to be assessed was due to their very early involvement in the initiation of in ammatory response [14]. In addition, IL-6 is not affected by anesthetic interventions alone, so it re ects the surgery-induced stress [15]. We found that dexmedetomidine was able to mitigate the early postoperative in ammatory response. Also, earlier studies were reported that dexmedetomidine decreased TNF-α and IL-6 concentrations in rats with sepsis [13,16] and alleviated in ammation in a rat model with spinal cord injury [7]. Furthermore, it signi cantly decreased the development of postoperative intraabdominal adhesions in rats with abdominal surgery [17]. This anti-in ammatory effect of dexmedetomidine was demonstrated also in clinical trials, where its administration postoperatively to patients requiring sedation and mechanical ventilation was associated with decreased concentrations of IL-6 levels [11]. Dexmedetomidine was reported also to decrease IL-1, TNF-α, and IL-6 concentrations in patients with sepsis [18].
Few studies have evaluated the anti-in ammatory effects of dexmedetomidine on surgery-induced in ammatory response, whose results were consistent with our study. Kang et al. [1] found that patients undergoing laparoscopic cholecystectomy who received dexmedetomidine had signi cantly lower concentrations of IL-1β, TNF-α, IL-10, and CRP with lower leukocytic count compared to the control participants. Ueki et al. [6] demonstrated that dexmedetomidine reduced the increase in postoperative IL-6 levels in patients undergoing cardiopulmonary bypass. Ding et al. [19] found dexmedetomidine to signi cantly decrease TNF-α and IL-6 compared to the control group in elderly patients undergoing laparoscopic radical prostatectomy. Li et al. [20] reported that dexmedetomidine reduced signi cantly the intraoperative and postoperative levels of TNF-α and IL-6 in patients undergoing open gastrectomy. Jiang et al. [21] stated that dexmedetomidine had signi cantly decreased IL-6 levels after open esophagectomy.
The mechanism of the anti-in ammatory effect of dexmedetomidine is not completely understood. Dexmedetomidine was postulated to modify the production of cytokines by macrophages and monocytes [22]. In addition, it was found to possess an antiapoptotic effect, which may contribute to protection against anesthetic-induced apoptosis in vivo and in vitro [23].
Moreover, dexmedetomidine could augment the phagocytic activity of macrophages in vitro [24]. Dexmedetomidine may also suppress in ammation through a central sympatholytic effect by stimulation of the cholinergic anti-in ammatory pathway [25]. Another proposed mechanism is inhibition of nuclear factor kappa B activation [26]. It might be possible that the antinociceptive action of dexmedetomidine contributes to its anti-in ammatory effect [27].
Ketamine is an anesthetic and analgesic drug with anti-in ammatory effect [28]. A meta-analysis concluded that ketamine has a signi cant inhibitory effect on postoperative IL-6 levels and thereby mitigates the early in ammatory response after surgery [5]. Moreover, ketamine has been shown to decrease the postoperative levels of TNF-α, IL-1β, IL-6 [29]. The current study showed that ketamine and dexmedetomidine suppressed the increase in the postoperative level of in ammatory markers, with no signi cant differences. This nding indicates that both drugs could be equally effective in attenuation of postoperative in ammatory response.
In our study, all patients were clinically stable and none needs any intervention, although HR and MAP were signi cantly increased in ketamine group and signi cantly decreased in dexmedetomidine group compared to the baseline values. Similar hemodynamic effects of dexmedetomidine were observed in several studies [19,20,30,31]. This is considered a myocardial protective effect of dexmedetomidine as it prevents the acute increases during airway management, reduces myocardial oxygen demand, and decreases the risk of myocardial injury [32].
We found that the recovery time was slightly higher in the dexmedetomidine group (13.5 ± 3.3 min) compared to the control group (12.6 ± 2.0 min), whereas the recovery time was signi cantly longer in the ketamine group (24.3 ± 6.4 min) than in the other two groups. In partial agreement to our results, previous studies showed that dexmedetomidine when co-administered with propofol associated with a longer recovery time from anesthesia [33,34]. The lack of signi cant difference in recovery time between the dexmedetomidine and control groups in our study may be attributed to the used protocol that differed from other studies. Delayed recovery time with ketamine administration was reported even with subanesthetic doses [35].
Evaluation of the adverse effects in our study elicited no signi cant differences among the studied groups. However, more adverse effects were recorded in the ketamine group. This difference in adverse events may bear clinical importance despite being statistically insigni cant. Dexmedetomidine has been shown to prevent emergence agitation [34] and postoperative vomiting[39] more effectively than ketamine. These ndings suggest that dexmedetomidine is safe and may be preferred over ketamine for having lower rate of adverse effects as well as maintenance of hemodynamic stability with myocardial protective effect and control of emergence agitation.

Limitations Of The Study
First, short term follow up of anti-in ammatory effect of the study drugs. Second, the study did not investigate the mechanism of action of the study drugs Further studies are proposed to compare different doses of dexmedetomidine and ketamine to know the minimum effective dose given by either continuous infusion or single injection. Furthermore, by evaluation of more in ammatory biomarkers the mechanism of action of dexmedetomidine could be concluded.

Conclusion
Dexmedetomidine and ketamine were comparable to each other as regards attenuation of the postoperative in ammatory response. However, the safety pro le of dexmedetomidine seems favorable over that of ketamine as evidenced by the former's lower rate of adverse effects with maintenance of hemodynamic stability.  The manuscript has been read and nally approved by all the authors.

List Of Abbreviations
Competing interests: The authors declare that they have no competing interests   data presented as percentage (%).