Download Procedure: The patient is placed in a supine position with

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INTRODUCTION: Brachial plexus block provides us alternative anesthesia technique to
General anesthesia for upper limb surgeries(1,2). Brachial plexus block is safer anesthesia
technique compared to General anesthesia in patients with high risk factors for surgery like
ischemic heart disease, cardiomyopathy, COPD, hypothyroidism. Of various local anesthetics,
commonly used are Lignocaine, Bupivacaine and Ropivacaine. Lignocaine use is restricted for
its limited duration of action. Ropivacaine for its higher cost and non-availability in our
institution. Bupivacaine can be safely used as it has longer duration of action.
Brachial plexus nerve blocks have analgesic and opioid sparing benefits for upper limb surgery.
Continuous brachial plexus block can provide prolonged postoperative analgesia and opioid
sparing effect. But its use is limited by its cost and management challenges. Single shot
peripheral nerve blocks as an alternative to General anesthesia have become a standard
anesthesia technique throughout the world. Single shot peripheral nerve block technique is
limited by the pharmacological duration and therapeutic index of local anesthetics.
Therefore adding an adjuvant analgesic is an alternative to prolong the analgesic duration and to
decrease the potential risk of side effects of local anesthetics by reducing the dose of local
anesthetics.
By increasing the duration of analgesia with a single shot block we can achieve a longer duration
of post-operative analgesia without significant clinical side-effects and hence we can avoid
continuous catheterization.
Many adjuvants have been added in the effort to prolong the duration of local anesthetics like
Epinephrine, Butorphanol tartrate, Dexamethasone, Tramadol, Buprenorphine, Verapamil,
Methylprednisolone, Clonidine, Dexmedetomidine(3). Of all the adjuvants Dexmedetomidine has
shown promising results and is completely devoid of complications (4).
Bupivacaine is a racemic mixture of stereoisomers belonging to amide class local anesthetics.
Dexmedetomidine, the pharmacologically active d-isomer of medetomidine is a highly specific
and selective α2 adrenoceptor agonist with α2:α1 binding selectivity ratio of 1620:1 as compared
to 220:1 for clonidine, thus decreasing the unwanted side effects of α1 receptors.
Presynaptic activation of α2 adrenoceptor in central nervous system (CNS) inhibits the release of
norepinephrine, terminating the propagation of pain signals and their postsynaptic activation
inhibits sympathetic activity, thereby decreasing HR and BP
Dexmedetomidine action have been shown to dose dependent and peripherally mediated.
A reduction of action potentials with dexmedetomidine which was not reversed with α2adrenergic receptor antagonists is Noted.4
High selectivity for α-2A receptors mediates analgesia, sedation, and anxiolysis. The research
done so far shows encouraging results for its use in intravenous sedation (ICU and operative
patients), spinal, epidural, caudal anesthesia, and Bier's block. By virtue of its effects on spinal
α2 receptors, it prolongs analgesia when used with local anesthetics for neuraxial blocks.
However all studies carried out so far to prove the peripheral action of α2 agonists were animal
studies. There are very few human studies, i.e. greater palatine and axillary brachial plexus nerve
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blocks have subsequently demonstrated that increased duration of sensory blockade can be
achieved by adding Dexmedetomidine to Bupivacaine and Levobupivacaine.
The present study is being undertaken to evaluate the onset time, duration of sensory and motor
block, postoperative analgesic duration, incidence of vomiting, requirements of rescue and
backup analgesia in first 24 hours with 0.25% Bupivacaine along with 50 ùg of dexmeditomidine
combination compared to 0.25% Bupivacaine for brachial plexus block by Supraclavicular
approach.
MATERIAL AND METHODS: This study was conducted in the Department of
Anesthesiology, Govt. Medical College, Anantapuramu after obtaining approval from intuitional
ethics committee. Informed consent was taken from the patients. The study was conducted over a
period of 6 months. Only those who gave willful written consent were included in the study. 60
patients of age groups 18 to 80 years undergoing upper limb surgery under supraclavicular
brachial plexus block were enrolled in a prospective, randomized, double-blind, placebocontrolled trial.
Patients were randomly allocated in this double blind study (using a sealed envelope technique)
into two groups, each group containing 30 patients.
Group C-received 40 ml of 0.25% Bupivacaine plus 2 ml. of normal saline.
Group Dex-received 40 ml of 0.25% Bupivacaine plus 50ùg of dexmedetomidine.
INCLUSION CRITERIA: ASA class1, 2 & 3, age group between 18 to 80 years, consenting
patients.
EXCLUSION CRITERIA: Unwilling patients, ASA class 4 & 5, infection at the site of
injection, presence of coagulopathies, hypersensitivity to Bupivacaine & Dexmedetomidine.
patients with a history of significant neurological, psychiatric, neuromuscular, cardiovascular,
pulmonary, renal, hepatic disease, alcoholism or drug abuse, pregnancy or lactating women
patients with morbid obesity, diabetes, peripheral vascular disease and patients receiving
adrenoceptor agonist or antagonist therapy or chronic analgesic therapy.
On the day before surgery patients were explained about the procedure to be undertaken and the
benefits and risks involved in the procedure. All the patients were explained about the visual
analogue scale (VAS) and made well conversant with it. All the patients were instructed to
remain in fasting state from 9 pm onwards and Tab. Alprazolam 0.5 mg. given orally as an
anxiolytic.
After arrival of patients in the operation theatre, they were allotted C and DEX groups by sealed
envelope technique.
Patient is secured with 18G Cannula on the opposite hand to be operated and maintenance fluid
Dextrose normal saline is started. Patient is monitored with multichannel monitor for NIBP,
Pulse rate, SPO2, temperature and 3 lead ECG. Inj. Midazolam 1 mg. given intravenously before
block to reduce the anxiety and discomfort during the block. All the resuscitation equipment and
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the general anesthesia equipments are kept ready in case of inter scalene nerve block
complication and block failure.
The patients were administered dose of normal saline & dexmedetomidine according to their
group category mixed with 0.25% Bupivacaine.
Procedure: The patient is placed in a supine position with the head turned away from the side to
be blocked. The arm to be anesthetized should be adducted, and the hand should be extended
along the side toward the ipsilateral knee as far as possible. The midpoint of the clavicle should
be identified and marked. The posterior border of the sternocleidomastoid can be palpated easily
when the patient raises the head slightly. The palpating fingers can then roll over the belly of the
anterior scalene muscle into the interscalene groove, where a mark should be made
approximately 1.5 to 2.0 cm posterior to the midpoint of the clavicle. Palpation of the subclavian
artery at this site confirms the landmark.[1,2]
After appropriate preparation and development of a skin wheal, the anesthesiologist stands at the
side of the patient facing the patient's head. A 22-gauge, 4-cm needle is directed in a caudad,
slightly medial, and posterior direction until a paresthesia or motor response is elicited or the first
rib is encountered.
Paresthesia and motor response of the arm or shoulder are equally efficacious.
After elicitation of Paresthesia 40 ml of 0.25% Bupivacaine mixed with 2 ml. of normal saline is
injected in Group C and 40 ml. of 0.25% Bupivacaine mixed with 50ùg of dexmedetomidine
injected in Group DEX.
Strict vigilance is kept for the complications of Supra clavicular block like intravascular injury
and Pneumothorax is 0.5% to 6%. Other complications include frequent phrenic nerve block
(40% to 60%), Horner's syndrome (ptosis, miosis, anhydrosis), and neuropathy. The presence of
phrenic or cervical sympathetic nerve blockade normally requires only reassurance. Although
nerve damage can occur, it is uncommon and usually self-limited.[1,2,5]
Onset time of block (time for surgical anesthesia) is defined as the time gap between the
completion of local anesthetic injection to pinprick discrimination.
Postoperatively all the patients were shifted to the recovery room ICU. For first 24 hours.
Patients were assessed for pain, nausea and vomiting.
Postoperative pain assessed with visual analogue scale (VAS) score of 0-10 (0=no pain,
10=worst imaginable pain).VAS scores >4 were treated with. Inj. Diclofenac sodium 75 mg.
intra muscularly. If analgesia is still inadequate after 30 minutes inj. pentazocine 30 mg.
intravenous given. The total administered doses of Diclofenac sodium and of pentazocine during
the first 24 hours was recorded. Time for the first analgesic requirement was noted.
Duration of postoperative analgesia was defined as the time between last suture application and
requirement for first rescue analgesic at VAS score > 4.
Patients were monitored throughout the study period for evidence of feeling of pain during
surgery and acceptance of the procedure.
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Sensory block was assessed by the pin prick method. Assessment of sensory block was done at
each minute after completion of drug injection in the dermatomal areas corresponding to median
nerve, radial nerve, ulnar nerve and musculocutaneous nerve till complete sensory blockade.
Sensory onset was considered when there was a dull sensation to pin prick along the distribution
of any of the above-mentioned nerves. Complete sensory block was considered when there was
complete loss of sensation to pin prick.
Sensory block was graded as:
Grade 0: Sharp pain felt.
Grade 1: Analgesia, dull sensation felt.
Grade 2: Anesthesia, no sensation felt.
Assessment of motor block was carried out by the same observer at each minute till complete
motor blockade after drug injection. Onset of motor blockade was considered when there was
Grade 1 motor blockade. Peak motor block was considered when there was Grade 2 motor
blockade. Motor block was determined according to a modified Bromage scale for upper
extremities on a 3-point scale:
Grade 0: Normal motor function with full flexion and extension of elbow, wrist and fingers.
Grade 1: Decreased motor strength with ability to move the fingers only.
Grade 2: Complete motor block with inability to move the fingers.
The block was considered incomplete or failed block when patient didn’t have analgesia even
after 30 min of drug injection.
Patient was monitored for hemodynamic variables such as heart rate, blood pressure and oxygen
saturation every 5 min after the block intraoperatively and every 60 min post-operatively.
Assessment of blood loss was done and fluid was administered as per the loss. Duration of
surgery was noted.
The intra- and post-operative assessment was done by another anesthesiologist who was unaware
of the drug used. Patients were assessed for duration of analgesia as per a numeric rating scale of
0 to 10. The numeric rating scale was recorded post-operatively every 60 min till the score of 4.
The rescue analgesia was given in the form of inj. Diclofenac sodium (1.5 mg/kg)
intramuscularly at the VAS ≥4 and the time of administration was noted.
All patients were observed for any side-effects like nausea, vomiting, dryness of mouth and
complications like pneumothorax, hematoma, local anesthetic toxicity and post-block neuropathy
in the intra- and post-operative periods.
Comparison between two groups was done by using student’s t-test. p value <0.05 was
considered statistically significant, value <0.01 was considered highly significant, value >0.05
was considered insignificant.
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RESULTS:
There is no significant differences with respect to age, gender and duration of surgical procedure
in two groups (table no=1). The anesthesia technique is similar in two groups
Parameters
Age (YEARS)
Gender (M:F)
HEIGHT (CM)
WEIGHT (KG)
DURATION OF SURGERY (MINUTES)
Group C
48.2±17.07
17:13
165.1±7.2
57.9±7.9
53.7±23.42
Group DEX
46.76±17.51
16:14
166.4±8.1
62.4±8.6
57.4±21.34
TABLE 1: Demographic profile
The onset of action of Supra clavicular block had no significant difference between two groups.
PARAMETERS
TIME(MINUTES)
GROUP C
6.46±2.41
GROUP DEX
6.5±2.64
P VALUE
0.95
TABLE 2: Time for onset of action of SUPRACLAVICULAR BLOCK
Duration of motor block is significantly higher in group DEX compared to group C.6
PARAMETER
TIME(MINUTES)
GROUP C
GROUP DEX
128.66±34.93 279±72.04
P VALVE
0.0000001
TABLE 3: Duration of MOTOR BLOCK
Duration of sensory block is significantly higher in group DEX compared to group C[7].
PARAMETER
GROUP C
GROUP DEX
TIME (MINUTES)
201.0±49.38
451.56±129.30
TABLE 4: Duration of SENSORY BLOCK
P VALVE
0.0000001
Time for onset of pain in the postoperative period is significantly prolonged in group DEX
compared to group C[6,7,8].
PARAMETER
TIME(MINUTES)
GROUP C
201.0±49.38
GROUP DEX
451.56±129.30
TABLE: 5 Time for onset of pain in the postoperative period
P VALVE
0.0000001
6
500
450
400
350
300
GROUP C
250
GROUP DEX
200
150
100
50
0
O.B
D.M.B
D.S.B
D.O.A
Figure 1: Comparison of mean onset time block (OB); duration of motor block (DMB) and
sensory block (DSB); and duration of analgesia (DOA). The time difference between the two
groups was statistically very significant (P < 0.001)
There is no significant difference between the two groups for administration of Diclofenac
potassium in the first 24 hours of postoperative period as rescue analgesia.
PARAMETER
Dosage
GROUP C
75±0.0
GROUP DEX
75±0.0
TABLE 6: Diclofenac potassium dose administration in the postoperative period
Pentazocine administration in the first 24 hours of postoperative period is significantly lower in
group DEX compared to group C.(8)
PARAMETER
GROUP C
GROUP DEX
P VALVE
Dosage(MG)
30±0.0
4±10.37
0.0001
TABLE 7: Opioid dose administration in the postoperative period
Incidence of postoperative nausea and vomiting is significantly less in group DEX than group
C(9).
PARAMETER
GROUP C
GROUP DEX
P VALVE
FREQUENCY
0.56±0.50
0.066±0.25
0.000099
TABLE: 8: Incidence of postoperative nausea and vomiting in the postoperative period
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DISCUSSION: Regional anesthesia by using Supra clavicular Brachial plexus block has been
used as ideal alternative to general anesthesia in patients with high risk factors for surgery under
general anesthesia. Single shot brachial plexus block usage is limited by early onset of
postoperative pain, high opioid dosage administration and higher incidence of postoperative
vomiting, which can be managed by adding an adjuvant to local anesthetics. Advantages of
adding adjuvant to local anesthetic include prolongation of sensory block, motor block, delayed
onset of pain in the postoperative period, low dosage administration of opioid analgesics in the
postoperative period and lower incidence of postoperative vomiting.[10,11]
In our study the surgeries varied from surgical neck of Humerus to lower end fractures of radius,
ulna and fingers. No major complications were encountered in our study.
High selectivity of Dexmedetomidine for α-2A receptors mediates analgesia, sedation, and
anxiolysis. The research done so far shows encouraging results for its use in intravenous sedation
(ICU and operative patients), spinal, epidural, caudal anesthesia, and Bier's block. By virtue of
its effects on spinal α2 receptors, it prolongs analgesia when used with local anesthetics for
neuraxial blocks.
Studies by Brummett et al., showed that dexmedetomidine enhances duration of Bupivacaine
anesthesia and analgesia of sciatic nerve block in rats without any evidence of histopathological
damage to the nerve[11]. In another study, dexmedetomidine added to Ropivacaine increased the
duration of sciatic nerve blockade in rats, most likely due to the blockade of hyperpolarizationactivated cation current (i.e., a direct effect on the peripheral nerve activity). Kosugi et al.,
examined the effects of various adrenoceptor agonists including dexmedetomidine, tetracaine,
oxymetazoline and Clonidine, and also an α2 adrenoceptor antagonist (atipamezole) on
compound action potential (CAP) recorded from frog sciatic nerve, and found that CAPs were
inhibited by α2 adrenoceptor agents so that they were able to block nerve conduction[19].
Yoshitomi et al., demonstrated that dexmedetomidine as well as Clonidine enhanced the local
anesthetic action of Lignocaine via peripheral α-2A adrenoceptors.(4) Studies have shown that
Clonidine when added to Bupivacaine prolongs the duration of anesthesia and analgesia in
brachial plexus block, but was associated with bradycardia, hypotension, and respiratory
depression as side effects[4]. Masuki et al., suggested that dexmedetomidine induces
vasoconstriction via α2 adrenoceptors in the human forearm possibly also causing
vasoconstriction around the site of injection, delaying the absorption of local anesthetic and
hence prolonging its effect[20]. Esmaoglu et al., reported prolongation of axillary brachial plexus
block when dexmedetomidine was added to levobupivacaine[14].
To conclude in view of profound postoperative analgesia, delayed onset of pain in
postoperative period, low dosage requirement of opioid, lower incidence of postoperative
vomiting, lower rate of complications along with early ambulation and discharge makes supra
clavicular block with local anesthetic with adjuvant an ideal alternative anesthesia technique to
General anesthesia in selected group of patients with high risk factors for General anaesthesia.
[12,13,15]
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CONCLUSION: Addition of Dexmedetomidine as an adjuvant to Bupivacaine for Supra
clavicular brachial plexus block significantly prolongs the duration of sensory and motor block,
decrease dose of postoperative Diclofenac and opioids requirements, decreased incidence of
postoperative nausea and vomiting in patients undergoing upper limb surgeries (9). Duration of
motor block & sensory block is significantly prolonged in Dexmedetomidine group with
significant difference in postoperative Diclofenac and opioid requirement and incidence of
postoperative nausea and vomiting.
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