European Journal of Cardiovascular Medicine

Balanced general anaesthesia encompasses amnesia, analgesia, hypnosis, muscle relaxation, and suppression of reflexes. Achieving these components typically requires a combination of agents. Intraoperative awareness—defined as unintended patient wakefulness or recall of events under anaesthesia ^[1,2] —is a rare but distressing phenomenon, with incidence ranging from 0.1% to 0.9% in general surgeries and higher in obstetric and cardiac procedures ^[5,8]. Its psychological consequences include nightmares, flashbacks, anxiety, PTSD, and fear of future anaesthesia ^[5,6,17].

Awareness can be explicit (conscious recall) or implicit (influencing behaviour without conscious recall). Risk factors include low anaesthetic doses, patient-specific variability, and certain comorbidities. Reliable monitoring remains challenging, as traditional indicators like heart rate or blood pressure are nonspecific. While devices like the Bispectral Index (BIS), based on EEG data, are considered helpful in monitoring anaesthetic depth [10,12,13], their high cost limits their availability in many institutions [22].

In economically constrained settings like ours, the Brice Questionnaire—administered postoperatively—remains a practical and validated tool to assess intraoperative awareness and explicit recall [1,7,22]. This questionnaire-based approach enables assessment even without advanced monitoring tools.

Propofol, a sedative-hypnotic, is commonly used due to its rapid onset and antiemetic properties. Dexmedetomidine, an alpha-2 agonist, provides sedation and analgesia without respiratory depression and may reduce anaesthetic requirements. This study compares their efficacy in preventing awareness and their impact on intraoperative hemodynamics.

Ethical Considerations

This prospective, randomized, single-blinded study was conducted in the Department of Anaesthesiology at Maharajah’s Institute of Medical Sciences (MIMS), Vizianagaram, Andhra Pradesh, India over a period of 6 months, from             to                 . Approval was obtained from the Institutional Ethical Committee. Written informed consent was secured from all participants.

A total of 60 ASA I/II patients, aged 18–65 years scheduled for elective open cholecystectomy under general anaesthesia were randomly divided into 2 equal groups. Group P received inj.Propofol 2 mg/kg induction + 3 mg/kg/hr infusion while Group D received inj. Dexmedetomidine 1 mcg/kg bolus over 10 minutes + 0.2–0.6 mcg/kg/hr infusion

Inclusion Criteria: Adults aged 18-65 years, ASA I/II, weight 35–70 kg, height 150–170 cm.

Exclusion Criteria: ASA III/IV, hearing or speech difficulties, neurological or psychiatric disorders, hepatic or renal dysfunction, allergy to study drugs, NYHA class IV, use of antipsychotics or sedatives, and emergency surgeries.

Anaesthesia Protocol

All patients were secured with intravenous access and standard baseline monitoring. Premedication consisted of intravenous glycopyrrolate at a dose of 0.004 mg/kg. Fentanyl 2 mcg/kg IV was administered prior to induction. Anaesthesia was induced with propofol 2 mg/kg IV and suxamethonium 2 mg/kg IV. Maintenance was carried out using isoflurane at 0.4% in a 67% nitrous oxide and oxygen mixture, supplemented with vecuronium for neuromuscular blockade.

Group P received a propofol infusion at 3 mg/kg/hr, while Group D received dexmedetomidine 1 mcg/kg IV over 10 minutes, followed by a maintenance infusion of 0.5 mcg/kg/hr. To minimize ambient operating room noise and standardize auditory input, all patients were provided with intraoperative music via headphones.

Postoperative Assessment

The Brice Questionnaire was administered 24 hours post-extubation to evaluate recall. The five standard questions included:

Table 1: Brice Questionnaire

If explicit recall was reported, follow-up questions explored sensations (pain, sound, paralysis), duration, attempts to alert staff, and emotional consequences. Based on responses, patients were classified  as having definite, possible, or no awareness.

Hemodynamic Monitoring: HR, MAP, and SpO₂ were recorded at baseline, induction, intubation, incision, and every 15 minutes intraoperatively.

Statistical Analysis

Data were analyzed using SPSS v22. Continuous variables were compared using unpaired t-tests; categorical data via Chi-square test. A p-value < 0.05 was considered statistically significant.

Primary outcome: Incidence of intraoperative awareness at 24 hours post-extubation.

Secondary outcomes: Trends in hemodynamic stability (HR and MAP) and frequency of intraoperative adverse events.

Demographics and Baseline Characteristics

There were no statistically significant differences in age, gender distribution, ASA status, or weight between the groups.

Hemodynamic Parameters

MAP and HR were significantly more stable in Group D compared to Group P.

Table 2: Mean Arterial Pressure (MAP) : (mm hg)

Figure 1: comparison of mean arterial pressure (mm hg)

Table 3: Comparison of Heart Rate at Various Time Points (bpm)

Figure 2 : Heart rate (bpm)

Incidence of Intraoperative Awareness: 

Table 4:  Incidence of Intraoperative Awareness in Both Groups

Incidence of Intraoperative Awareness in Both Groups

Note: Awareness assessed using the Brice Questionnaire administered 24 hours post-extubation.

Figure 3 : Intraoperative awareness incidence

Adverse Events: Mild bradycardia was noted in 3 patients in Group D; hypotension in 5 patients in Group P.

This prospective, randomized study demonstrates that dexmedetomidine is significantly more effective than propofol in preventing intraoperative awareness and maintaining intraoperative hemodynamic stability in patients undergoing open cholecystectomy. These findings are consistent with prior literature and reinforce the role of dexmedetomidine as a valuable adjunct in general anaesthesia, particularly in resource-constrained settings[3,4,20].

Intraoperative awareness is a rare but psychologically distressing phenomenon, with reported incidences varying between 0.1% to 0.2% in low-risk cases, and up to 1% in high-risk populations such as trauma, cardiac, or obstetric patients. In our study, the use of the Brice Questionnaire, a validated and widely used postoperative interview tool, helped identify three awareness events (10%) in the propofol group and none in the dexmedetomidine group. This difference was statistically significant (p = 0.04), indicating a true clinical benefit of dexmedetomidine in awareness prevention.

Dexmedetomidine is a highly selective alpha-2 adrenergic agonist that acts centrally on the locus coeruleus, reducing norepinephrine release and resulting in sedation, anxiolysis, analgesia, and amnesia without respiratory depression and reduces sympathetic output [3,14,15]. It produces a unique sedative state known as “cooperative sedation” [15,19] , in which patients are calm, rousable, and free from distress. These properties not only reduce the need for additional anaesthetic agents but also contribute to suppression of explicit memory formation, a key mechanism for reducing awareness.

On the contrary, propofol, although widely used for induction and maintenance due to its favourable pharmacokinetics, lacks intrinsic analgesic or significant amnestic properties at lower infusion rates [4,5]. Its effectiveness depends heavily on precise titration and is often used in combination with opioids and inhalational agents. In the absence of depth-of-anaesthesia monitoring tools such as BIS, subtherapeutic dosing or inter-patient variability in pharmacodynamics may result in inadequate sedation and unintentional awareness, as observed in this study.

In terms of hemodynamic stability, our study also showed superior outcomes with dexmedetomidine. The pressor responses to intubation, incision, and surgical manipulation were significantly blunted in the dexmedetomidine group compared to the propofol group. Mean arterial pressure (MAP) and heart rate (HR) remained more stable in Group D throughout the intraoperative period, consistent with earlier studies demonstrating the sympatholytic properties of dexmedetomidine.

Importantly, no patient in the dexmedetomidine group experienced intraoperative awareness, supporting prior findings such as those by Thejasvi et al., who showed that dexmedetomidine at 0.5 mcg/kg/hr significantly suppressed explicit memory compared to propofol at 50 mcg/kg/min. Their use of BIS and the Brice Questionnaire aligns with our methodology, further reinforcing the reliability of subjective tools in assessing awareness when BIS monitoring is not feasible.

In our study, isoflurane was maintained at 0.4% in combination with 67% nitrous oxide, which together provide an additive anesthetic effect. However, nitrous oxide has limited amnestic properties and may not be sufficient to prevent awareness when used alongside low-dose propofol without depth monitoring [13,22].

Although BIS monitors are considered the gold standard for evaluating anaesthetic depth, their cost, limited availability, and dependence on disposable sensors often make them impractical in lower-income or rural hospitals. In such settings, the Brice Questionnaire remains an essential, cost-effective alternative, particularly when administered systematically postoperatively. Its ability to distinguish between dreaming and awareness, and to quantify explicit recall, makes it a valuable endpoint in awareness-related research and clinical monitoring.

In addition to pharmacological strategies, the use of non-pharmacological methods like ambient noise control, use of soothing music (as done in this study), and minimizing operating room disturbances can further reduce the likelihood of awareness. Monitoring clinical signs such as movement, tachycardia, hypertension, sweating, or lacrimation can also provide indirect clues to inadequate anaesthesia.

This study demonstrates that dexmedetomidine is superior to propofol in preventing intraoperative awareness and maintaining intraoperative hemodynamic stability. These findings are consistent with previous literature supporting dexmedetomidine’s sedative, analgesic, and amnestic effects.

Dexmedetomidine, a selective alpha-2 agonist, induces sedation resembling non-REM sleep and reduces sympathetic output. This unique pharmacological profile enables it to provide stable anaesthesia without respiratory depression. In contrast, propofol lacks intrinsic analgesic properties and may not reliably suppress conscious perception at lower doses.

Dexmedetomidine’s ability to blunt the stress response to intubation and incision [20,21] contributed to its superior performance in maintaining hemodynamic parameters. Propofol was associated with more variability and higher rates of hypotension.

No awareness was reported in the dexmedetomidine group, while 10% of patients in the propofol group reported definite or possible awareness. These findings suggest that dexmedetomidine provides an additional margin of safety in patients at risk of intraoperative recall.

In our setting, the Brice Questionnaire served as a reliable, low-cost method for assessing awareness postoperatively [1,7,22]. Though BIS monitoring is considered the gold standard, its cost and limited availability restrict its use in low-resource environments.

Supporting literature such as Thejasvi et al.[7] and Roy et al. [9] further validates the use of dexmedetomidine and subjective tools like the Brice Questionnaire in avoiding explicit recall, particularly where EEG-based monitoring is unavailable.

While this study presents compelling evidence, it is not without limitations. The sample size is relatively small (n=60), and the single-center design may limit generalizability. Furthermore, the reliance on patient self-reporting through the Brice Questionnaire, although validated, may underreport subtle awareness episodes. Larger multicenter trials with BIS comparison arms could provide more robust conclusions.

Dexmedetomidine is more effective than propofol in preventing intraoperative awareness and provides superior hemodynamic control. The Brice Questionnaire serves as a practical and accessible tool for awareness assessment in institutions without BIS monitoring, especially in low-resource settings.

Additional Disclosures-

Funding: This study received no external funding and was conducted as part of institutional academic research.

Conflict of Interest: The authors declare no conflicts of interest related to this study.

Ethical Approval: Ethical clearance was obtained from the Institutional Ethics Committee of Maharajah’s Institute of Medical Sciences, Vizianagaram. All participants provided written informed consent prior to enrollment.

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