Table of Contents  
ORIGINAL ARTICLE
Year : 2016  |  Volume : 9  |  Issue : 4  |  Page : 563-568

Monitored anesthesia care with propofol or dexmedetomidine for patients undergoing upper limb surgeries under brachial plexus blockade: a comparative study


1 Department of Anaesthesiology and Critical Care, Subharti Medical College, Swami Vivekanand University, Meerut, Uttar Pradesh, India
2 Department of Radiodiagnosis and Interventional Imaging, Subharti Medical College, Swami Vivekanand University, Meerut, Uttar Pradesh, India

Date of Submission21-Oct-2015
Date of Acceptance02-Jul-2016
Date of Web Publication12-Jan-2017

Correspondence Address:
Kumkum Gupta
(Anesthesia), 108-109, Chanakyapuri, Shastri Nagar, Meerut 250004, Uttar Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1687-7934.198253

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  Abstract 

Background
Brachial plexus block is widely used for upper limb surgeries but intraoperatively patients remain aware. The present study aimed to compare the sedative efficacy and safety of propofol infusion versus dexmedetomidine infusion for monitored anesthesia care during upper limb surgeries under ultrasound (US)-guided brachial plexus blockade.
Patients and methods
Sixty adult consented patients of American Society of Anesthesiologists physical status I–III of both sexes were given 20 ml of 0.75% ropivacaine (150 mg) for brachial plexus blockade under US guidance. The patients were randomized into two groups of 30 patients each, to receive either propofol infusion [group I (P)] or dexmedetomidine infusion [group II (D)] during the intraoperative period. The primary goals were to achieve a sedation score of 2–3 on the Ramsay sedation scale and to compare the duration of postoperative analgesia assessed using the visual analog scale. The hemodynamic stability, respiratory depression, or any complication due to technique or medications was also recorded as secondary outcomes.
Results
US guidance helped visualization of the nerves, the needle, and the spread of local anesthetic at the brachial plexus block site. Desired sedation score of 2–3 was effectively achieved with intraoperative infusions of dexmedetomidine and propofol. Hypotension occurred in 11 patients of the propofol group, whereas no episode of hypotension was noted in the dexmedetomidine group. Bradycardia was evident in five patients of the dexmedetomidine group. The duration of postoperative analgesia with dexmedetomidine infusion was significantly prolonged when compared with propofol infusion as assessed using visual analog scale. Respiratory depression did not occur in any patient. No adverse events inherent to sedative medication or technique were observed in any patient.
Conclusion
The clinical efficacy and safety of dexmedetomidine was better than propofol due to prolonged postoperative analgesia and intraoperative hemodynamic stability without respiratory depression.

Keywords: brachial plexus blockade, dexmedetomidine, monitored anesthesia care, propofol, ropivacaine, ultrasound guidance


How to cite this article:
Gupta K, Tyagi V, Gupta PK, Rastogi B, Jain M, Bansal M. Monitored anesthesia care with propofol or dexmedetomidine for patients undergoing upper limb surgeries under brachial plexus blockade: a comparative study. Ain-Shams J Anaesthesiol 2016;9:563-8

How to cite this URL:
Gupta K, Tyagi V, Gupta PK, Rastogi B, Jain M, Bansal M. Monitored anesthesia care with propofol or dexmedetomidine for patients undergoing upper limb surgeries under brachial plexus blockade: a comparative study. Ain-Shams J Anaesthesiol [serial online] 2016 [cited 2017 Sep 23];9:563-8. Available from: http://www.asja.eg.net/text.asp?2016/9/4/563/198253


  Introduction Top


Brachial plexus blockade is an efficient regional anesthetic technique for the upper limb surgery with the advantage of minimal alteration in hemodynamics. A single injection of local anesthetic drug is adequate as the brachial plexus is enclosed in a fascial sheath [1]. Ultrasound (US) guidance helps to detect the anatomical variants of brachial plexus and allows imaging of individual nerves and related anatomical structures and monitoring of local anesthetic drug spread in appropriate tissue planes during injection [2],[3],[4].

Monitored anesthesia care combines the intravenous sedation with regional anesthetic techniques. The intravenous sedation is used to diminish the anxiety and apprehension of patients with depressed level of consciousness without obtunding the protective reflexes. The patient remains appropriately responsive to verbal commands and able to maintain the airway independently [5]. Several techniques of intravenous sedation are available during regional anesthetic blocks with primary goals to achieve sedation while maintaining arousibility, cooperation, and hemodynamic and respiratory stability.

Current treatment of choice includes intravenous midazolam, opioids, and propofol, but these medications are associated with limitations of respiratory depression, lack of orientation, severe hypotension, and gastrointestinal hypomotility. Low-dose propofol infusion to maintain a plasma concentration of 1–1.5 μg/ml is appropriate for sedation in conjunction with regional anesthesia [6]. Dexmedetomidine produces cooperative sedation, and hence is indicated for sedation during the surgical procedures under regional anesthetic techniques. The dosage of sedatives is titrated to attain the desired score of sedation (2–3) on the Ramsay sedation scale [7].

The present study aimed to compare the sedative efficacy and safety of propofol infusion with dexmedetomidine infusion for monitored anesthesia care during upper limb surgery under US-guided brachial plexus blockade.


  Patients and methods Top


After approval of the Institutional Ethical Committee and obtaining written informed consent, 60 patients of American Society of Anesthesiologists physical status I–III of both sexes between 18 and 58 years of age and BMI less than 25 who were scheduled for elective upper limb surgery were enrolled for this prospective randomized study from August 2014 to July 2015 in the Department of Anesthesiology and Critical Care, CSS Hospital, associated to NSCB Subharti Medical College, Meerut, Uttar Pradesh, India. All patients were subjected to preanesthetic assessment. Exclusion criteria were as follows: presence of clinically significant coagulopathy; infection at the injection site; allergy to local anesthetics; pre-existing neuromuscular, cardiovascular, and hepatic diseases; refusal to technique; and inability to visualize the brachial plexus with US guidance. Any patients taking psychotropic medications or receiving chronic analgesic therapy other than simple analgesics were also excluded from the study.

Patients were admitted before the day of surgery and fasting of at least 6 h was ensured. On arrival to the operation theater, intravenous access was established and lactated Ringer’s intravenous infusion was started at the rate of 6–8 ml/kg for all patients to replenish the overnight fasting. Standard monitoring comprising noninvasive blood pressure (BP), heart rate (HR), ECG, and pulse oximetry (SpO2) was instituted for all patients throughout the surgical procedure.

Brachial plexus block was performed using the supraclavicular approach with a transportable US system (SonoSite MicroMax; SonoSite Inc., Bothell, Washington, USA) with 38 mm 8–13 MHz linear high frequency transducer (HFL-38). Under all aseptic precautions, the US transducer was placed in sagittal plane in the supraclavicular fossa to visualize the brachial plexus, located lateral and superior to the subclavian artery between the anterior and middle scalene muscles. A 23 G 40 mm short bevelled echogenic needle for optimal control and visibility was placed deep to the caudal elements of the brachial plexus, and a predetermined volume of 20 ml of 0.75% (150 mg) ropivacaine was administered around the brachial plexus after negative aspiration to avoid accidental intravascular injection. A 3 min local massage was performed to facilitate an even drug distribution.

After establishment of brachial plexus blockade, the patients were randomized according to computer generated random number table into two comparable equal groups of 30 patients each.

Patients of group I (P) received propofol infusion at a rate of 5 μg/kg/min, and then the rate was increased by increments of 5–10 μg/kg/min until the desired score of sedation of 2–3 on the Ramsay sedation scale was achieved.

Patients of group II (D) were administered a loading dose of 1 μg/kg of dexmedetomidine over 10 min, followed by a maintenance infusion of 0.2–0.7 μg/kg/h, and the rate was adjusted to achieve the desired score of sedation 2–3 on the Ramsay sedation scale.

A minimum period of 5 min between adjustments was allowed for onset of peak drug effect. In both groups, infusion of study drug medication was continued during the intraoperative period until the surgery was completed.

The onset of sensory block was assessed using the pinprick method using a 25 G hypodermic needle in the appropriate area using a three-point scale for pain (2, sharp pain; 1, blunt pain; and 0, no pain) and the onset time of sensory block was the time from completion of the injection to first loss of pinprick sensation in any dermatome. Motor weakness was assessed by hand grip and movement at the elbow, wrist, and fingers, using a modified Bromage scale (grade 0: normal motor function, able to raise the extended arm to 90° for 2 s; grade 1: able to flex the elbow and move the fingers but unable to raise the extended arm; grade 2: unable to flex the elbow but able to move the fingers; grade 3: complete motor block, unable to move the arm, elbow, and fingers). The onset time of motor block was the time from completion of the injection to first loss of motor power [8].

Patients were assessed for onset of sensory and motor blockade every 5 min until the desired surgical anesthesia was achieved, with time 0 min being the time of completion of the injection. Duration of sensory blockade was defined as the time from onset of sensory block until the complete recovery of sensation. Duration of sensory analgesia was defined when patient demanded the first rescue analgesic and was assessed using the visual analog scale. Duration of motor block was the time from onset of motor block to complete recovery of motor power of upper limb and was determined by asking the patients to note the time when they could first move their fingers of blocked limb.

All patients were assessed for the level of sedation using the Ramsay sedation scale: 1, awake patient is anxious and agitated or restless or both; 2, patient is cooperative, oriented, and tranquil; 3, patient responds to commands and asleep; 4, patient exhibits brisk response to stimulus; 5, patient exhibits a sluggish response to stimulus; and 6, patient exhibits no response [9].

Intraoperative arterial BP, HR, and peripheral oxygen saturation were recorded, and any incidence of hypotension, bradycardia, or fall in peripheral oxygen saturation was noted and managed according to clinical protocol. Patients were also observed for any discomfort, nausea, vomiting, shivering, pain, or any other side effect. Any need for additional medication was also recorded.

The sample size was calculated with standard computer programs, which computed that ∼24–26 patients should be included in each group to detect a clinically significant difference of hemodynamic parameters between the groups for type 1 error of 0.05 and power of 80%. Assuming a 5% dropout rate, the total sample size of 60 patients was set. The obtained data are expressed as mean and SD, considering the latter as the best predictor. Statistical analysis was performed using statistical program SPSS, 11.5 version software (SPSS Inc., Chicago, Illinois, USA) for comparing observed data using Student’s t-test, the χ2-test, and the Mann–Whitney U-test, as appropriate. A P-value less than 0.05 was considered statistically significant.


  Results Top


The present study compared the sedative efficacy and safety of propofol infusion with dexmedetomidine infusion for monitored anesthesia care during brachial plexus blockade that was successfully completed on 60 consented adults. The US-guided visualization of the brachial plexus, needle, and spread of local anesthetic in the supraclavicular region was consistent in all enrolled patients. The surgical anesthesia was clinically effective and scheduled surgical procedure could be performed uneventfully in all patients. All patients were cooperative with subsequent assessment of block characteristics.

Patients of both groups were comparable with respect to the demographic profile and surgical factors ([Table 1]). The infusion rate of study drugs was adjusted to achieve a Ramsay sedation score of 2–3 throughout the surgery. There were no surgical or anesthetic complications. None of the patients needed supplemental analgesia during surgery.
Table 1: Demographic profile of patients

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The baseline recordings of HR, systemic BP, and oxygen saturation were comparable between the two groups. The study showed that intraoperative dexmedetomidine infusion effectively stabilized the hemodynamic parameters of HR and BP when compared with intraoperative propofol infusion.

Eleven patients of the propofol group suffered from hypotension (systolic BP<100 mmHg), which was managed with rapid intravenous infusion of crystalloid solution, and no patients required any intervention with vasopressor medication. The BP remained stable in all patients of the dexmedetomidine group. Bradycardia (HR<60 beats/min) was observed in five patients of the dexmedetomidine group, which was normalized by reducing the rate of dexmedetomidine infusion and no patient required atropine. No patients of the propofol group suffered from bradycardia ([Table 2]).
Table 2: Hemodynamic parameters

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The duration of postoperative sensory analgesia was longer in patients of the dexmedetomidine group (327.53±24 min) compared with the propofol group (296.47±34 min), with a statistically significant difference between the two groups (P=0.037) ([Table 3]). The two groups showed an average visual analog scale score of 3 during pain assessment in the postoperative period, but pain intensity was significantly reduced with dexmedetomidine infusion in comparison with propofol infusion at 20 min, 1 h, and 2 h postoperatively.
Table 3: Sensory and motor blockade characteristics

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Dexmedetomidine and propofol infusion, both effectively achieved the desired level of sedation (score of 2–3 on the Ramsay sedation scale). None of the patients showed any complication or adverse effects inherent to the dexmedetomidine or propofol infusion. The respiratory rate and peripheral oxygen saturation were comparable between the two the groups. None of the patients complained of difficulty in breathing or showed clinical evidence of respiratory depression or a drop in oxygen saturation below 95% on room air. No side effects of nausea, vomiting, or pruritus were observed in any patient. Postoperatively, there was no recall of intraoperative events in any patient. All patients were completely awake, able to obey commands, and could walk without difficulty ([Table 4]).
Table 4: Properties, complications, and adverse events of propofol and dexmedetomidine infusion

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  Discussion Top


Surgical anesthesia is a pharmacologically induced state that renders the patient insensible to noxious surgical stimulation. It is not a single pharmacologic process but is the result of the interaction of hypnotics and analgesics in a synergistic manner. The hypnotic component (unconsciousness) is created by the administration of intravenous and inhaled anesthetics, whereas the analgesic component is created by the administration of either opioids or local anesthetics (regional anesthesia). Some drugs such as ether, nitrous oxide, ketamine, and α-2 agonists provide both hypnotic and analgesic components to some degree [10].

Monitored anesthesia care combines sedative–hypnotic with regional anesthesia to provide patient comfort, analgesia, and sedation while allowing the patient to maintain oxygenation and airway control independently [11]. Patients under monitored anesthesia care experience fewer incidences of nausea and vomiting and can be discharged home safely and quickly [12].

Brachial plexus blockade is preferred over general anesthesia for upper limb surgeries in the day care setting. The brachial plexus is most compactly arranged in the supraclavicular region [1] and hence this site was chosen for brachial plexus blockade for the present study.

The US imaging directs the targeted nerve under live guidance, with concurrent visualization of important vascular and other adjacent structures, and hence improves success rate. The risks of intra-arterial injection or a pneumothorax are negligible [13],[14],[15]. In the present study, the small volume of 20 ml of 0.75% ropivacaine has produced reliable and intense blockade with negligible risks of intra-arterial injection or a pneumothorax. During the study, the brachial plexus was successfully blocked, with no significant difference in the onset of sensory and motor blockade between the two groups.

Intravenous sedation is used for adult patients to diminish anxiety and apprehension without obtunding protective airway reflexes. Several techniques of intravenous sedation are available during regional block with primary goals to achieve sedation while maintaining arousibility, cooperation, and hemodynamic and respiratory stability, whereas deep sedation is avoided due to risk for apnea [10].

Current choices for intravenous sedation include midazolam, opioids, and propofol, but their use is associated with respiratory depression, lack of orientation, hypotension, and gastrointestinal hypomotility. A low-dose infusion of propofol to maintain plasma concentration of 1–1.5 μg/ml or a short-acting barbiturate (10–20 mg of methohexital or 25–75 mg of thiopental) is appropriate for sedation in conjunction with regional anesthetic technique to produce a depressed level of consciousness. Midazolam (1–2 mg) with or without fentanyl (12.5–25 μg) or sufentanil (2.5–5 μg) is a common regimen [7].

Propofol has many properties of sedative–hypnotic for use in monitored anesthesia care but has only minimal analgesic property. The context-sensitive half-time of propofol remains shortened even after prolonged infusion. It may cause some respiratory depression and hemodynamic instability but showed excellent recovery profile [6].

Dexmedetomidine is a highly selective α-2 adrenergic receptor agonist and produces both analgesia and cooperative sedation, a state closely resembling physiological stage II of nonrapid eye movement sleep, and hence the patients can be easily awakened. This action is not mediated by γ-amino-butyric acid-mimetic system, and hence it does not depress the respiratory drive during sedation and showed little effect on ventilation. The activation of the α-2 agonist receptors in the brain (locus coeruleus) and the spinal cord decreases sympathetic outflow causing dose-dependent sedation, analgesia, hypotension, and bradycardia [16],[17],[18].

Dexmedetomidine exerts its clinical effects through α-2 receptors in the locus coeruleus and hemodynamic manifestation through the direct and indirect actions of the sympathetic nervous system. It has peripheral vasoconstrictive effect that causes hypertension. The unique feature is the absence of substantial respiratory depression [12].

Continuous infusion of a short-acting drug is superior to intermittent bolus dosing, as it produces less fluctuation in drug concentration and also reduces the total amount of drug. Drugs were titrated using adjustable infusion to avoid excessive sedation. If noxious stimulus was increased or decreased, the concentration of drugs were increased or decreased.

The present study showed that intraoperative dexmedetomidine infusion effectively stabilized the hemodynamic parameters of HR and BP when compared with intraoperative propofol infusion. Hypotension was observed in 11 patients of the propofol group due to peripheral vasodilation, which could be managed with rapid intravenous infusion of crystalloid solution only and vasopressor medication was not required. Bradycardia was observed in five patients of the dexmedetomidine group because of its effect on α-2 adrenoceptors, which was managed by reducing the rate of dexmedetomidine infusion, and atropine was not given in any patient.

Our study indicates that the duration of postoperative analgesia was enhanced in patients who were given dexmedetomidine infusion during brachial plexus block when compared with patients given propofol infusion, and the difference between the groups was statistically significant.

Awareness and postoperative recall of events during anesthesia is an important clinical problem. Drugs with sedative–hypnotic properties reduce attention to stimuli as a direct consequence of depression of consciousness. Dexmedetomidine and propofol, both medications have amnesic effects at subhypnotic doses. None of the patients of the present study could recall intraoperative events due to adequate level of sedation. These results of present study are in accordance with the study by Arain et al. [19].

Al-Mustafa et al. [20] studied the effect of intravenous dexmedetomidine infusion during spinal anesthesia with bupivacaine and concluded that intravenous dexmedetomidine administration prolonged the sensory and motor blockade of spinal anesthesia with good sedation and hemodynamic stability. We also observed the prolonged duration of sensory analgesia in the dexmedetomidine group as compared with the propofol group.

Kaygusuz et al. [21] have comparatively evaluated the sedation of dexmedetomidine with propofol during shockwave lithotripsy and concluded that dexmedetomidine has had better analgesic properties and respiratory function of the patients was better maintained than with propofol. Our study also showed the same results.


  Conclusion Top


The intraoperative dexmedetomidine infusion produces adequate sedation, maintained the hemodynamic stability with respiratory adequacy, and enhanced the duration of postoperative analgesia. US guidance has facilitated the accurate perineural placement of local anesthetic drug. The relative clinical efficacy and safety of dexmedetomidine was significantly better compared with propofol.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

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Marhofer P, Greher M, Karpal S. Ultrasound guidance in regional anesthesia. Br J Anesth 2005; 95:226–230.  Back to cited text no. 15
    
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Akada S, Takeda S, Yoshida Y, Nakazato K, Mori M, Hongo T et al. The efficacy of dexmedetomidine in patients with noninvasive ventilation: a preliminary study. Anesth Analg 2008; 107:167–170.  Back to cited text no. 16
    
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Arain SR, Ebert TJ. The efficacy, side effects, and recovery characteristics of dexmedetomidine versus propofol when used for intraoperative sedation. Anesth Analg 2002; 95:461–466.  Back to cited text no. 19
    
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Al-Mustafa MM, Badran IZ, Abu-Ali HM, Al-Barazangi BA, Massad IM, Al-Ghanem SM. Intravenous dexmedetomidine prolongs bupivacaine spinal analgesia. Middle East J Anaesthesiol 2009; 20:225–231.  Back to cited text no. 20
    
21.
Kaygusuz K, Gokce G, Gursoy S, Ayan S, Mimaroglu C, Gultekin Y. A comparison of sedation with dexmedetomidine or propofol during shockwave lithotripsy: a randomized controlled trial. Anesth Analg 2008; 106:114–119.  Back to cited text no. 21
    



 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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