Functional Endoscopic Sinus Surgery (FESS) has revolutionized the treatment of various head and neck pathologies, offering improved precision and outcomes. However, it presents significant challenges for anesthesiologists, particularly regarding intraoperative blood loss. Excessive bleeding can obscure the surgical field, increasing operative time and risk of complications [1].Controlled hypotension, defined as reducing systolic blood pressure to 80–90 mmHg, mean arterial pressure (MAP) to 50–65 mmHg, or achieving a 30% reduction from baseline MAP, is an effective strategy to minimize bleeding and improve surgical visibility [2]. Various pharmacological agents can induce controlled hypotension, including nitrates, beta-blockers, calcium channel blockers, and alpha-2 agonists [3,4]. Clonidine, an alpha-2 adrenergic agonist, exhibits sedative, analgesic, and hypotensive effects via central sympatholysis. In contrast, esmolol is a cardio-selective beta-1 receptor blocker characterized by rapid onset, short duration, and absence of intrinsic sympathomimetic or membrane-stabilizing activity at therapeutic doses. This study aims to compare the efficacy and safety of clonidine and esmolol in achieving controlled hypotension during FESS, focusing on hemodynamic parameters such as heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and MAP.

Aim

To compare the effectiveness and safety of clonidine and esmolol as hypotensive agents in achieving controlled hypotension during functional endoscopic sinus surgery (FESS).

Objectives

1. To assess and compare the intraoperative hemodynamic parameters (heart rate, systolic blood pressure, diastolic blood pressure, and mean arterial pressure) between clonidine and esmolol groups during FESS.

To evaluate and compare the postoperative recovery profiles, including emergence time, sedation scores, time to first rescue analgesic requirement, and incidence of postoperative complications, between the two groups

After obtaining approval from the Institutional Ethics Committee this prospective, randomized interventional study was conducted from April 2023 to August 2024 in the ENT operating theater of a tertiary care hospital. All procedures adhered to the Declaration of Helsinki guidelines [5].

A total of 68 patients scheduled for FESS under general anesthesia (GA), aged 20–60 years, weighing 45–65 kg, and classified as American Society of Anesthesiologists (ASA) physical status I or II, were assessed. Patients with a history of hypertension, coronary artery disease, coagulopathy, recurrent sinus surgery, orbital abscess, or known drug allergies were excluded. Ultimately, 60 patients met the inclusion criteria and were randomized into two groups (n = 30 each) using the opaque sealed envelope method. Allocation was performed by a colleague not involved in patient care, ensuring allocation concealment.

Preoperative evaluations included thorough history-taking, physical examination, and routine laboratory investigations. Written informed consent was obtained from all patients.

On arrival in the operating room, standard monitors were attached, and baseline HR, SBP, DBP, MAP, and SpO₂ were recorded. An 18G intravenous cannula was inserted, and Ringer lactate infusion commenced at 10 mL/kg. Premedication included ondansetron 0.15 mg/kg, midazolam 0.02 mg/kg, glycopyrrolate 4 µg/kg, and fentanyl 2 µg/kg. Preoxygenation was performed with 100% oxygen. Induction was achieved using thiopentone sodium 5 mg/kg and succinylcholine 1.5 mg/kg, followed by tracheal intubation. Anesthesia was maintained with 40% O₂, 60% N₂O, atracurium 0.1 mg/kg, and isoflurane (0.4 MAC).

The study drug loading dose was administered 10 minutes before induction. Group A received clonidine 2 µg/kg diluted in 10 mL of 0.9% saline over 10 minutes, followed by a maintenance infusion of 1 µg/kg/hr. Group B received esmolol 1 mg/kg over 1 minute, followed by an infusion at 1 mg/kg/hr. Infusions were continued until 5 minutes before surgery completion or stopped earlier if hypotension occurred.

Intraoperative monitoring included HR, SBP, DBP, MAP, SpO₂, frequency of suctioning, and surgical field assessment. Surgical field quality was graded using the Fromme–Boezaart scale [6]:

• 0: No bleeding
• 1: Slight bleeding, no suctioning required
• 2: Slight bleeding, occasional suctioning required, surgical field not threatened
• 3: Slight bleeding, frequent suctioning required, surgical field threatened a few seconds after suction is stopped
• 4: Moderate bleeding, frequent suctioning, surgical field threatened immediately after suction is stopped
• 5: Severe bleeding, constant suctioning required, surgical field severely threatened

Hypotension was initially managed with fluid boluses; if unresponsive, the infusion rate was reduced or stopped. If required, mephentermine 6 mg IV was administered. Bradycardia (HR < 60 bpm) was managed by stopping the infusion and, if necessary, administering atropine 0.6 mg IV.

Reversal was achieved using neostigmine 0.05 mg/kg and glycopyrrolate 0.01 mg/kg IV, followed by extubation once patients were fully awake. Emergence time was defined as the interval from cessation of anesthetics to return of consciousness. Postoperative assessments included the Ramsay Sedation Score, emergence time, and VAS score every 30 minutes. Rescue analgesia (IV diclofenac 75 mg) was administered when VAS reached 3, and the time to first analgesic requirement was noted. Adverse effects such as nausea, vomiting, hypotension, bradycardia, headache, and flushing were recorded.

Sample size was calculated for 95% confidence and 80% power, anticipating a minimum detectable difference of 8 ± 10 mmHg in MAP one minute post-intubation. Data analysis was performed using SPSS version 22 (SPSS Inc., Chicago, IL). Categorical variables were compared using Chi-square tests, and continuous data were analyzed using Student’s t-test. A p-value < 0.05 was considered statistically significant.

Table 1. Demographic Variables

Table 2. Mean Heart Rate (MHR)

Table 3. Mean Arterial Pressure (MAP)

Controlled hypotension has significantly enhanced surgical dissection in functional endoscopic sinus surgery (FESS) by minimizing intraoperative blood loss. Excessive bleeding during FESS can obstruct the surgical field, potentially increasing tissue damage and the risk of postoperative adhesions, thereby affecting surgical outcomes [8]. While multiple studies have compared various hypotensive agents in FESS, direct comparisons between clonidine and esmolol are scarce. In this study, we evaluated and compared their effects on hemodynamic parameters, surgical field quality, emergence time, sedation, analgesic requirements, and postoperative complications.

Our study demonstrated that demographic parameters were comparable between the two groups, supporting the validity of our comparisons. Both clonidine and esmolol effectively achieved controlled hypotension, but clonidine produced more stable hemodynamics with consistently lower mean arterial pressure (MAP) and heart rate (HR) values. Furthermore, patients receiving clonidine experienced longer postoperative analgesia and emergence times, indicating its prolonged sedative and analgesic effects.

The fall in blood pressure with clonidine can be attributed to its central sympatholytic action via presynaptic α-2 adrenoreceptor activation, which reduces sympathetic outflow. Esmolol, by contrast, achieves hypotension through its negative chronotropic and inotropic effects, reducing cardiac output and systemic arterial pressure.

Our results align with the findings of Ibrahim et al. [9], who reported that clonidine controlled hemodynamic changes more effectively than esmolol in laparoscopic cholecystectomy. They also found that clonidine induced greater postoperative sedation — a result echoed in our study. Clonidine’s sedative action is mediated by its effects on the locus coeruleus (LC), an area rich in α-2 receptors that plays a major role in arousal and autonomic control.

Similar observations were reported by Bafna et al. [4], who compared dexmedetomidine and clonidine in FESS and concluded that both drugs achieved stable hemodynamics and improved surgical conditions, with clonidine contributing to conscious sedation. Pathak et al. [10] also highlighted that preoperative clonidine infusion delayed rescue analgesic requirements and enhanced postoperative sedation, attributed to its action on the dorsal horn of the spinal cord and the ventrolateral preoptic nucleus.

In our study, blood loss and the surgical field quality, assessed using the Fromme–Boezaart scale, were comparable between groups and predominantly scored 2 or 3, reflecting satisfactory field visibility. Kumar et al. [11] also reported similar surgical field scores (1 or 2) when comparing dexmedetomidine and clonidine during FESS.

Contrastingly, Hamed et al. [12] evaluated esmolol in patients undergoing open myomectomy and found no significant reduction in mean HR and MAP, and only a nonsignificant reduction in blood loss. This discrepancy may stem from the lower esmolol dose used (0.5 mg/kg) compared to our study (1 mg/kg).

Regarding side effects, hypotension and bradycardia were more frequently observed in the clonidine group, albeit without statistical significance. These events resolved upon stopping the infusion, and none of the patients required pharmacologic interventions such as mephentermine or atropine. Similar observations were reported by Patil et al. [13], emphasizing the safety profile of these agents despite minor hemodynamic fluctuations.

Some limitations of our study warrant mention. Although we included both genders, male participants predominated, which may limit the generalizability of our findings across genders. Furthermore, invasive blood pressure monitoring was not employed, as it is not routine practice during FESS and would pose ethical concerns if used solely for research purposes. Blinding was not implemented; however, objective parameters were assessed by personnel not directly involved in the study, minimizing potential bias.

Compared to esmolol, clonidine offers superior hemodynamic stability, enhanced surgical field visibility, and additional benefits such as reduced intraoperative bleeding and extended postoperative analgesia in patients undergoing FESS. Clonidine also contributes to postoperative sedation, which may enhance patient comfort in the immediate recovery period. Its simplicity of administration, safety profile, and cost-effectiveness make clonidine a particularly attractive option for controlled hypotension in both developing and developed settings. Nevertheless, further research is needed to confirm these findings and explore their implications for postoperative sedation and recovery in larger, more diverse patient populations.

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