الفهرس 
SPINAL ANESTHESIAOnly 14 pages are availabe for public view
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Abstract
Lower abdominal surgeries performed under spinal anesthesia has the
advantage of having rapid onset, maintaining spontaneous breathing, relaxing
the necessary muscles for surgery, and cost effectiveness. It also has the
advantage of being free from the risks of intubation and pulmonary
aspiration.
Prolonging the duration of spinal anesthesia would allow longer
surgical interventions. Various additives have been used in order to prolong
the duration of spinal anesthesia, including vasoconstrictive agents such as
epinephrine, phenylephrine, and clonidine. Agents such as opioids and
neostigmine have also been used.
Dexmedetomidine is a centrally acting α2 receptor agonist that can be
titrated to the desired level of sedation without significant respiratory
depression. It has an analgesic-sparing effect, significantly reducing opioid
requirements both during and after surgery. Dexmedetomidine also has a
sympatholytic effect that can attenuate the stress response to surgery
mitigating tachycardia and hypertension. Because of its analgesic properties,
”cooperative sedation” and lack of respiratory depression, Dexmedetomidine
is increasingly being used as a sedative and adjuvant in anesthesia.
Dexmedetomidine has been used safely in patients undergoing surgical
procedures under regional anesthesia. Intravenous and intrathecal
dexmedetomidine showed to prolong the duration of spinal analgesia and
decrease postoperative analgesia.
Our study was designed to explore whether dexmedetomidine by intrathecal
or IV route has superior synergistic effects to bupivacaine spinal anesthesia in
patients undergoing lower abdominal surgery as regard patient
hemodynamics, spinal block characteristics, postoperative analgesia, level of
sedation and overall adverse effects.
With approval of the Institutional Ethical Committee of Faculty of
medicine, Menoufiya University, Egypt, and after patient’s written consent,
sixty ASA physical status I-II aged 20 to 60 years scheduled for lower
abdominal surgery with expected duration of 90-120 min under spinal
anesthesia were enrolled in this prospective randomized comparative study
Patients were excluded from the study if there was a patient refusal, history of
cardiac, liver, or kidney disease, history of allergy to amide local anesthetics
or medications included in the study, presence of any neurological problem,
and any contraindication for regional anesthesia, failed or unsatisfactory
spinal block.
All patients were randomly assigned using computer generated
randomized code into two groups. Group I patients received intrathecally 15
mg in 3.0 ml hyperbaric Bupivacaine with 5.0 µg in 0.5 ml Dexmedetomidine
followed by infusion of intravenous normal saline bolus and maintenance
volume equivalent to the group II patients throughout the whole period of
surgery. Group II patients received intrathecal hyperbaric Bupivacaine 15 mg
in 3.0 ml with normal saline 0.5 ml, followed by intravenous bolus dose of
Dexmedetomidine 0.5 µg /kg over 10 min followed by intravenous infusion
of a dose of 0.5 µg /kg/hr for the whole period of the surgery.
After careful sterilization, spinal anesthesia was carried out by 22
gauge Quincke spinal needle after skin infiltration with lidocaine local
anesthetic in L3-L4 level. The study drugs were prepared and given by an
anesthesiologist who was not involved in the study, in unlabeled syringes.
Both the anesthesiologist and who performed the block and recorded the
intra-operative data and the PACU nurse who recorded the postoperative data
were blinded to the patient’s group to which the patients were allocated.
Assessment parameters included: vital signs (Heart rate, systolic and
mean blood pressure, arterial oxygen saturation). Assessment of sensory
block included recording Time to reach T6 level, Peak sensory level and its
time and regression time to S1. Assessment of motor block included
recording the time to reach Bromage 3 motor block before surgery and the
regression time to Bromage 0 after surgery. Assessment of pain
intraoperatively and in PACU was assessed for 12 hours using visual
analogue pain scale (VAS) between 0-10 (0= no pain, 10 = the most severe
pain). Analgesics were given when VAS score >4 with recording of time for
first analgesic request and total analgesic consumption. Assessment of
sedation intraoperatively and in PACU was done by using Ramsay sedation
scale. Occurrence of any side effects as nausea, vomiting, headache, itching,
shivering, respiratory, or cardiovascular events, were recorded.
Study results were as following:
The patient groups were comparable as regarding age, sex, weight, height,
type of surgery, and ASA physical status with no statistical significance.
Systolic and mean blood pressure values were lower in group II than
group I during the first 90 minutes of surgery. Similarly, Heart rate values
were statistically significantly lower in group II than group I during the first
60 minutes of surgery. In addition, group I showed less total consumption of
atropine and ephedrine, and less overall side effects than group II.
Intrathecal dexmedetomidine was superior to the intravenous route as
regard bupivacaine spinal block characteristics. Group I had earlier sensory
onset to T6 dermatome, higher peak sensory level, prolonged sensory
regression time to S1 dermatome, lower mean 12 hours VAS scale, longer
time to first analgesic request, less total analgesic consumption than group
Although the mean onset time to reach Bromage 3 level of motor block was
comparable between both groups, the regression time to Bromage 0 was
prolonged in the intrathecal group.
However, intravenous dexmedetomidine was superior in providing
better intra-operative sedation level but this advantage was only limited to the
operative time, and both routes provided comparable sedation level in the
postoperative period.
We conclude from our study results that both intrathecal and
intravenous dexmedetomidine were safe adjuvants to bupivacaine spinal
anesthesia. Intrathecal dexmedetomidine is superior adjuvant to spinal
bupivacaine when compared to intravenous dexmedetomidine. It provides
more stable hemodynamics, greater augmentation to sensory and motor block,
better quality of perioperative analgesia and lesser overall side effects.
Intravenous dexmedetomidine provides higher level of sedation during the
intra-operative period.