|Year : 2020 | Volume
| Issue : 2 | Page : 42-45
Comparison of efficacy and safety of dexmedetomidine versus propofol infusion for maintaining depth of general anesthesia when muscle relaxants are not used
Pulak Tosh, Sunil Rajan, Naina Narayani, Karthik Chandra Babu, Niranjan Kumar, Jerry Paul
Department of Anaesthesia, Amrita Institute of Medical Sciences, Amrita Vishwa Vidyapeetham, Kochi, Kerala, India
|Date of Submission||01-Feb-2020|
|Date of Acceptance||16-Mar-2020|
|Date of Web Publication||11-May-2020|
Dr. Sunil Rajan
Department of Anaesthesiology, Amrita Institute of Medical Sciences, Amrita Vishwa Vidyapeetham, Kochi, Kerala
Source of Support: None, Conflict of Interest: None
Background: In surgeries where direct nerve stimulation is required intraoperatively, the use of long-acting muscle relaxants should be avoided. The study aimed to assess the efficacy of dexmedetomidine versus propofol infusion in providing an adequate depth of general anesthesia where long-acting muscle relaxants were not used intraoperatively and to compare hemodynamics in both the groups. Patients and Methods: It was a prospective randomized controlled study done in forty patients undergoing total parotidectomy or brachial plexus surgeries. Group D received an intravenous (IV) bolus of dexmedetomidine 1 mcg/kg body weight before induction, followed by infusion at 0.7 mcg/kg/h intraoperatively. In Group B, the infusion of propofol was started at a rate of 1.5 mg/kg/h to a maximum of 100 mg/h after intubation. In both the groups, if the patient moved, bucked on the endotracheal tube, or if there were signs of inadequate depth of anesthesia, a bolus of propofol 0.5 mg/kg IV was given and repeated as required. Statistical analysis was performed using Mann–Whitney U-test and Fisher's exact test. Results: The number of times propofol bolus was required intraoperatively did not show any significant difference between groups. The mean heart rate was significantly lower in Group D before induction. At any other time points, the mean systolic blood pressure and mean arterial blood pressure were comparable in both the groups. Conclusion: Both dexmedetomidine and propofol infusions are equally effective and safe in providing an adequate depth of general anesthesia as reflected by patient immobility during surgeries where long-acting muscle relaxants were not used.
Keywords: Brachial plexus, dexmedetomidine, general anesthesia, propofol
|How to cite this article:|
Tosh P, Rajan S, Narayani N, Babu KC, Kumar N, Paul J. Comparison of efficacy and safety of dexmedetomidine versus propofol infusion for maintaining depth of general anesthesia when muscle relaxants are not used. Bali J Anaesthesiol 2020;4:42-5
|How to cite this URL:|
Tosh P, Rajan S, Narayani N, Babu KC, Kumar N, Paul J. Comparison of efficacy and safety of dexmedetomidine versus propofol infusion for maintaining depth of general anesthesia when muscle relaxants are not used. Bali J Anaesthesiol [serial online] 2020 [cited 2021 Feb 24];4:42-5. Available from: https://www.bjoaonline.com/text.asp?2020/4/2/42/284184
| Introduction|| |
Muscle relaxants play an important role in anesthesia. Although they do not provide any pain relief or produce unconsciousness, their use is often necessary to help the surgeon achieve the best possible operating conditions under general anesthesia. Nevertheless, in surgeries where direct nerve stimulation is required intraoperatively, either to identify nerves or to check their integrity, such as during total parotidectomy or brachial plexus surgeries, the use of long-acting muscle relaxants is to be avoided. Increased depth of anesthesia can usually be provided with supplemental intravenous (IV) infusions of propofol or dexmedetomidine but may be associated with hemodynamic instability.
The primary objective of the present study was to assess the efficacy of dexmedetomidine versus propofol infusion in providing an adequate depth of general anesthesia as reflected by the patient's immobility during surgeries where long-acting muscle relaxants were not used intraoperatively. The secondary objectives included the comparison of hemodynamic parameters, use of vasopressors or inotropes, and the time taken to extubate with the use of both drugs.
| Patients and Methods|| |
This was a prospective, randomized controlled trial in forty adult patients aged 20–60 years of the American Society of Anesthesiologist (ASA) physical status (PS) 1 and 2 who underwent total parotidectomy or brachial plexus surgeries under general anesthesia. Patients with significant hepatic, renal, or cardiac diseases and those with a history of allergy to test drugs were excluded from the study. The study period was between January 2017 and August 2019, and it was conducted after obtaining Institutional Ethical Committee Clearance and consent from the study participants.
The patients were randomly and equally allotted to either Group D (dexmedetomidine) or Group P (propofol) based on a computer-generated random sequence of numbers. With the use of sequentially numbered opaque sealed envelopes, concealment of allocation was done. General anesthesia was given to all patients following a standard institutional protocol. We used standard ASA monitoring equipment in this study.
Patients of both the groups were given injection glycopyrrolate 0.2 mg, midazolam 2 mg, and fentanyl 2 mcg/kg intravenously before induction. The induction of general anesthesia was with propofol 2–2.5 mg/kg. We went on with the administration of suxamethonium 2 mg/kg; patients were intubated with a 7.5 or 8.0 mm flexometalic endotracheal tube (ET) as appropriate. Anesthesia was maintained with end-tidal sevoflurane 2% in oxygen and nitrous oxide (1:1) under mechanical ventilation with a tidal volume of 6–8 mL/kg and respiratory rate of 12–16/min maintaining end-tidal carbon dioxide (CO2) between 25 and 30 mmHg.
Following induction, an intravenous infusion of dexmedetomidine was administered in patients of Group D at the rate of 0.7 mcg/kg/h. In the presence of hypotension, the infusion rate was reduced to 0.5 mcg/kg/h. In Group B, an IV infusion of propofol was started at a rate of 1.5 mg/kg/h to a maximum of 100 mg/h after intubation.
In both the groups, if the patient moved, bucked on ET tube, or if there were signs of inadequate depth of anesthesia such as heart rate (HR) >100/min and systolic blood pressure (SBP) >140 mmHg, the depth of anesthesia was increased with an IV bolus of injection propofol 0.5 mg/kg. In the event of bradycardia (HR <60/min), glycopyrrolate 0.2 mg or atropine 0.6 mg bolus were administrated accordingly. A fall in SBP to <90 mm Hg was managed by a fluid bolus of 200 ml. If the hypotension did not respond to fluid bolus, the rate of dexmedetomidine infusion was decreased to 0.5 mcg/kg/h in Group D and that of propofol to 1 mg/kg/h in Group P. If hypotension lasted >5 min, phenylephrine 50 mcg boluses were given IV in both the groups. Sustained hypotension warranted the use of noradrenaline infusion.
We recorded the HR, SBP, and mean arterial pressures (MAP) before any intervention (baseline data), before induction, and at 5, 10, 15, 30, 45, 60, 90, and 120 min after induction. Intraoperatively, the number of patient movements requiring propofol boluses were noted. Time to extubate was defined as the time from discontinuing all anesthetics until the time of extubation.
Statistical analysis was performed using SPSS 20.0 (IBM Corp. Released 2011. IBM SPSS Statistics for Windows, version 20.0. IBM Corp., Armonk, NY, USA). Mann–Whitney U-test was used to compare the demographics and hemodynamic parameters in both the groups. Fisher's exact test was used to compare the intraoperative patient movements in both the groups. P < 0.05 was considered statistically significant.
| Results|| |
Data of forty patients were analyzed in the present study. Demographic variables, distribution of ASA PS, did not show any statistically significant difference between the groups [Table 1]. Baseline mean HR, SBP, and MAP was comparable in both the groups. The mean HR was significantly lower in Group D before induction. HR at other time points did not show any significant difference between the groups [Figure 1]. The mean SBP [Figure 2] and MAP was comparable in both the groups during the study period. The number of times propofol bolus was required intraoperatively did not show any significant difference between the groups [Table 2]. The requirement of anticholinergics and vasopressors also was comparable in both the groups.
|Table 1: Comparison of demographics and American Society of Anesthesiologist physical status|
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|Table 2: Extubation time and the use of intraoperative propofol and vasopressor|
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| Discussion|| |
The practice of providing muscle relaxation has become an established part of the classic anesthesia triad alongside unconsciousness (hypnosis) and pain relief and has important advantages. The introduction of nondepolarizing muscle relaxants in anesthesia helped anesthetists to provide optimal surgical conditions by ensuring an immobile patient with lower doses of volatile or IV anesthetics and thereby maintaining hemodynamic stability. However, the use of muscle relaxants interferes with neuromuscular conduction, and hence, these agents are avoided when nerve stimulation studies are to be performed intraoperatively.
Different techniques are in practice to provide patient immobility when nondepolarizing muscle relaxants are contraindicated intraoperatively due to various reasons. Transtracheal injection of lidocaine has proved to be a better alternative to propofol and dexmedetomidine infusions.,,, The disadvantage of this technique is that the block has to be administered when the patient is awake. The technique is associated with coughing while the drug is being injected into the trachea, which causes discomfort to the patient.
Dexmedetomidine, an imidazole compound, is the pharmacologically active dextro-isomer of medetomidine. It displays selective α2-adrenoceptor agonistic actions, with analgesic and sedative-sparing properties while maintaining hemodynamic stability.,, It augments the actions of other anesthetic agents, resulting in perioperative sympatholysis, thereby reducing blood pressure by stimulating central α2 and imidazoline receptors. It is commonly used for deepening the plane of anesthesia intraoperatively. When used along with propofol, it significantly reduces the dose of propofol infusion required to increase anesthetic depth. It is generally considered as a safe adjuvant analgesic agent in those patients who are prone to opioid-induced respiratory depression in the postoperative period. The most frequent adverse events observed following the administration of a large bolus of dexmedetomidine are bradycardia and hypertension. It is an expensive drug to use and has to be given as an infusion under careful monitoring to provide a uniform depth of anesthesia.
Propofol is a commonly used IV agent for induction and maintenance of general anesthesia, which exerts its sedative actions on the central nervous system at various neurotransmitter receptors, mainly gamma-aminobutyric acid A receptor. Recovery from propofol-induced anesthesia is generally rapid and associated with less frequent side effects. When used for maintenance, the infusion should immediately follow the induction dose to provide satisfactory and continuous anesthesia. The most common side effects of propofol are hypotension and bradycardia. Propofol without muscle relaxants has provided good operating conditions in patients with myasthenia and muscular dystrophy.,
Both propofol and dexmedetomidine are commonly used drugs during scoliosis surgery with intraoperative neurophysiology monitoring. Propofol-based and remifentanil-based anesthesia has been found advantageous over sevoflurane and remifentanil for intraoperative neurophysiology studies in scoliosis surgery in children. Similarly, dexmedetomidine administered at a rate of 0.4 μg/kg/h, as an adjuvant of sevoflurane inhalational anesthesia, was shown to improve the wake-up test quality and maintained hemodynamic stability during scoliosis surgery.
Combining propofol and dexmedetomidine in optimal doses provides cardiovascular stability with less adverse effects while maintaining a similar onset time of propofol. Another study showed that the addition of dexmedetomidine to propofol maintained consistent depth of anesthesia with significantly lesser requirements of propofol but with hemodynamic depression and early postoperative sedation. During subarachnoid block, dexmedetomidine is recommended as an adjunct for intraoperative sedation because of its stable cardiopulmonary profile, sedative, and analgesic actions.
In our study, we did not combine both propofol and dexmedetomidine to avoid polypharmacy and also to assess the efficacy of the individual drugs in providing patient immobility with hemodynamic stability. The major limitation of our study was that it was not a blinded study. Only the patient and outcome assessor were blinded. The study, however, could be extended to larger patient populations, and different doses of the individual drugs need to be tested to find the optimum agent and dose, which will provide ideal surgical conditions and hemodynamic stability without compromising patient safety.
| Conclusion|| |
Both dexmedetomidine and propofol infusions are equally effective and safe in providing an adequate depth of general anesthesia as reflected by patient immobility during surgeries where longacting muscle relaxants are not used intraoperatively.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2]