الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 32 |  |  |
| | | from | 32 | | |
Abstract
Perioperative pain management is a medical and human necessity, within the last two decades awareness of pain management is growing rapidly.
The proper management of perioperative pain is not only a humanitarian requisite, it affects post operative rehabilitation, morbidity and even mortality. Also proper pain management is associated with better patient satisfaction and decrease hospitalization time and cost.
Although local anesthetics are the foundation of regional anesthesia, they carry some disadvantages. That leads to development and the use of wide variety of adjuvant agents to be used with them, to enhance and prolong their actions. This allows decreasing total consumption of the used drugs and accordingly the suspected side effects.
These adjuvants are compounds that have undesirable or low potency effect, but in combination with local anesthetics and opioids allow reducing their dose. Many adjuvants are used in regional anesthetic practice. The most commonly used adjuvants are opioids, α2 adrenoreceptor agonists (such as Dexmedetomedine and Clonidine), NMDA antagonists (such as Ketamine and Magnesium Sulfate) and Acetyl choline estrase inhibitors (Neostagmine).
Magnesium Sulfate showed to have NMDA antagonistic prosperities In vitro studies. Intrathecal Magnesium Sulfate has shown to potentiate morphine antinocieption in a postoperative model. Several studies documented beneficial effect for epidural and Intrathecal Magnesium Sulfate in improving postoperative analgesia in several procedures including Cesarean section and thoracic surgery.
Concerning Dexmedetomidine, it is highly selective α2 adrenoreceptor agonist with selectivity ratio of 1600:1 (α2: α1). It is the pharmacologically active dextro-enantiomer of medetomidine. Because of its α2adrenoceptor agonist properties, Dexmedetomidine has a broad range of pharmacological properties, including sedation associated with arousability and orientation and without respiratory depression. Additional effects includes analgesia, anxiolysis, hemodynamic stability, anti-shivering effect, reduced nausea and vomiting and anesthetic sparing effect.
Aim of the work:
Our study was designed to explore whether dexmedetomidine or MgSo4 as an adjuvant to bupivacaine has better analgesic properties when compared to plain bupivacaine in post TKR epidural analgesia.
Patients and methods:
This study is double blind randomised study comparing plain Bupivacaine and Bupivacaine plus one of two adjuvant drugs through epidural in postoperative pain control after TKR. Sixty patients were randomised into three groups group (B) received plain Bupivacaine 0.5% (2.5ml) + 7.5 ml normal saline (producing 10 ml of bupivacaine 0. 125%), group (BM) received plain Bupivacaine 0.5% (2.5ml) + Magnesium sulphate 10% 0.5ml (50mg mgso4) + 7 ml normal saline (producing 10 ml of bupivacaine 0.125%), group (BD) received plain Bupivacaine 0.5% (2.5ml) +Dexmedetomidine 0.25 microgram/kg + volume completed to 10 ml using normal saline (producing 10 ml of bupivacaine 0.125%). Patients received epidural on demand when his VAS reaches 4.
Our measures included analgesic efficacy: including onset, peak and duration of analgesia (measured by visual pain scale), hemodynamic
stability (heart rate, ABP, respiratory rate), Motor blockade using Bromage scale and sedation using sedation score. Adverse effects and complications were recorded. Blood cortisol level was measured at the morning of the surgery and repeated one hour post operative and at morning for postoperative day one.
Results
In our study there was no statistically significant difference between the three groups regarding recorded demographic data (Age, sex distribution, ASA score and weight). Overall patients were elderly with mean age for group (B) 60.1±5.8, group (BM) 62.4±4.2 and 60.8±4.4 in group (BD).
Comparing analgesic characters among the three groups, group (BD) showed superior results with earlier onset, peak, and longer duration of analgesia. Which lead to statistically significant lower total Bupivacaine consumption and less need for rescue analgesic in group (BD).
Over all the three groups were safe with minimal hemodynamic instability. Only four patients developed hypotension (MAP< 75 mm hg) requiring support. The four patients were in group (BM) and that was statistically significant with P. value 0.01. MAP was lowest in group (BM) with mean 86.4± 3.4 vs. 94.5 ± 2.6 in group (BD) and 95.4 ± 2.1 in group (B) and difference was statistically difference with P. value .01.
Heart rate was overall stable with no patient developed persistent bradycardia (HR < 60) or tachycardia (HR > 100). There was no statistically significant difference between three groups regarding heart rate. With mean HR 93.5± 2.3 beat per minute in group (BM) , 73.6 ± 5.4 beat per minute in group (BD) and 92.7 ± 3.8 beat per minute in group (B).
Overall drugs used with low dose (analgesic dose) are well tolerated and has minimal side effects. In our study no patient developed sedation, motor block, respiratory depression (RR <10/min). There were no allergic reaction to any of the drug used and no patient developed neurological complications. Three patients developed nausea and vomiting in group (BM) versus one patient in group (BD) and group (B). Shivering was higher in group (B) as four patients developed shivering vs. one in group (BD) and no patient in group (BM). The differences were statistically insignificant for both shivering and nausea and vomiting.