In this study, the amount of bleeding in the dexmedetomidine group was less relative to the remifentanil group, leading to significantly higher surgeon satisfaction with the quality of the field of surgery and decreased frequency of suctioning. On the other hand, patient satisfaction was higher in the remifentanil group than in the dexmedetomidine group. However, the targeted hemodynamic goals were met to a greater in the dexmedetomidine group, which is why TNG was required in the remifentanil group but was not needed for any of the patients in the dexmedetomidine group. Patients in both groups had adequate analgesia, such that a pain score of above 3 on the VAS was never recorded and there was no need for narcotics (meperidine). Nonetheless, in the first minutes of entering the recovery ward, the degree of painlessness was less in the remifentanil group than in the dexmedetomidine group. According to the study protocol, paracetamol was injected for any patient who complained of mild pain (VAS less than 3). Therefore, due to the higher number of patients complaining of mild pain in the dexmedetomidine group, this group had greater painkiller use. Over time, the difference between the groups in this parameter decreased and the amount of painkiller consumption increased in the remifentanil group, though both painkiller use and pain score remained lower in the remifentanil group at all times. The RASS score was lower in the remifentanil group at the beginning of recovery, which probably explains the longer stay in recovery and longer time required to reach an Aldrete Score of 9–10 in patients in the dexmedetomidine group. On the other hand, the time until the return of spontaneous respiration and extubation was longer in the remifentanil group than in the dexmedetomidine group.

Bleeding is one of the most important and risky factors that affect the type and method of anesthesia chosen by surgeons and anesthesiologists. In the study of Bayram A et al., less bleeding and greater surgeon satisfaction were achieved using dexmedetomidine compared with magnesium sulfate among patients undergoing functional endoscopic sinus surgery. Furthermore, the amount of TNG use for controlling the blood pressure was also less in the dexmedetomidine group [13].

Qin Ye et al., in a study of patients undergoing laparoscopic cholecystectomy, found that using the right dose of dexmedetomidine gives rise to hemodynamic stability [14]. At high doses, dexmedetomidine inhibits the release of epinephrine and norepinephrine by stimulating presynaptic a2-adrenoreceptors and increased parasympathetic tone, thereby promoting hemodynamic stability [15, 16]. This mechanism probably explains the greater hemodynamic stability witnessed at all times in the dexmedetomidine group of our study relative to the remifentanil group. However, immediately following intubation, the efficacy of dexmedetomidine decreased leading to a peak in blood pressure and heart rate. This is probably due to the release of a large amount of epinephrine and norepinephrine following laryngoscopic stimulation and intubation, surpassing the neutralization capacity of dexmedetomidine at the dosage used. It should be noted that such a sudden rise in blood pressure and heart rate following intubation was also seen in the remifentanil group.

Hemodynamic stability is one of the most important factors that affect the level of bleeding and, consequently, the surgeon’s satisfaction with the operation. In the study of Somayaji A et al., which was performed on patients undergoing functional endoscopic sinus surgery, the researchers found that hemodynamic fluctuations were minimal, leading to increased surgeon satisfaction and better surgical outcomes [11]. Rokhtabnak F et al. demonstrated that during rhinoplasty, dexmedetomidine had a greater ability to stabilize hemodynamic parameters than magnesium sulfate, giving rise to greater surgeon satisfaction with the quality of the surgical field [17].

Pain and its complications can prolong the recovery time and maximize patient dissatisfaction. Therefore, various drugs are provided to reduce postoperative pain. The initial painlessness in the remifentanil group was probably due to the cumulative effects of the residual levels of narcotics and their metabolites (morphine and fentanyl), with the patients’ complaints of pain increasing gradually as the effect of the drugs disappeared and the RASS score increased [18]. On the other hand, the analgesic effects of dexmedetomidine are delivered through the hyperpolarization of interneurons along with a decrease in the release of the substance P and glutamate neurotransmitters, representing a weaker analgesic effect than that of remifentanil, which is in agreement with the findings of previous studies [15, 16].

Previous studies indicate that dexmedetomidine exerts its sedative effects by blocking presynaptic and post-synaptic a2-adrenergic receptors and that its mechanism of sedation, unlike drugs such as narcotics and benzodiazepines, is not through affecting the gamma-aminobutyric acid system. Patients are likely to be in an arousable and cooperative state when awakened from anesthesia, which averts delirium [15, 19, 20]. Considering that remifentanil suppresses respiration to a greater degree than dexmedetomidine, the time of the return of spontaneous respiration and also the time required for extubation was longer in the remifentanil group relative to the dexmedetomidine group [21,22,23]. In the study of Maud AS Weerink et al., it was found that the analgesic effect of dexmedetomidine was less than remifentanil up to the level of 2.4 ng/ml, and a targeted level of these drugs can be achieved using the mentioned systems [15].

In this study, there were many limitations, which could be eliminated through the use of larger sample sizes, Bispectral Index (BIS) monitoring, and a target-controlled infusion (TCI) system. This would improve the monitoring of the level of consciousness and sleep of the patients and would allow the measurement of drug use with greater accuracy.

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