Authored by Asghar Karbord*
Abstract
Aim: there are many reports about the efficacy of analgesics in reducing postoperative pain after lumbar decompressive surgery. This study aimed to investigate the effect of subdermal and intramuscular injection of bupivacaine on the severity of postoperative pain after lumbar decompression surgery.
Material and Methods:
in this randomized double-blind trial, 50 patients who candidate for lumbar decompressive surgery elective for this them. Bupivacaine (0.25%) in the intervention group and normal saline (40 ml) in the control group were injected subcutaneously and intramuscularly. Factors of age, size of surgical cutting, number of operating spaces, duration of operation, the rate of need to analgesia, and the severity of pain at times of 3,12 and 24 hours after surgery were assessed.Results: the severity of pain in Bupivacaine group, in hours 3, 12 and 24 after postoperative surgery was less than control group (P value<0.05). Also, there was no significant difference between the two groups in terms of mean pain intensity using repeated measure design (P value<0.05). But within Bupivacaine group, pain severity significantly decreased during the 24 hours after surgery. (p<0.05)
Conclusion: Although bupivacaine (0.25%) results in reducing pain after surgery, more studies are recommended to investigate the effect of bupivacaine in combination with other drugs in cases of lumbar decompressive surgery. Also, it reduces pain during the 24 hours after surgery is very important.
Keywords: Bupivacaine; Pain relief; Lumbar decompression surgery
Introduction
Lumbar decompressive surgery is indicated whenever pain and neural complications of herniated discs, despite conservative treatment, continue. Lumbar decompression is a common procedure for treatment of spine pathology [1]. Despite progresses in realizing postoperative acute pain entity in recent decades, still 80% of patients suffer from pain after surgery [2]. Undermanaged pain could lead to depression, autonomic over-reaction and joints stiff ness [3,4]. Post laminectomy pain has been reported to be caused by some potential pathological changes occurring around the nerve tissue such as inflammation, edema, fibrosis and mechanical pressure on the posterior longitudinal ligament and central sensitization [5]. The origin of lumbar and back pain is irritation of no acceptors and mechanoceptors of vertebrae, discs, duramater, facet capsules, muscles and ligaments [3,6]. By activating the sympathetic system, uncontrolled postoperative pains may lead to complications and even death. Sympathetic activity increases myocardial oxygen consumption and causes cardiac ischemia and infarction [7]. Sympathetic activity may also decrease gastro-intestinal motility and depth of inspiration leading to paralytic ileus and respiratory complications [7]. Administration of non-steroidal anti- inflammatory drugs (NSAIDs) and opioids is a common method in postoperative pain control [8]. Using opioids alone in not effective in reducing these types of pains, so different drugs including corticosteroids and local anesthetics are also noted [9]. Although analgesics are usually used to control moderate to severe post discectomy pains, but their side effects reduce their applying range [4]. Local anesthetics affect cell wall proteins and inhibit secretion and activity of prostaglandins and nociceptors stimulating lysosome enzymes [10]. On the other way, local anesthetics, by inhibiting the Na pumps, block the transit of neural messages along the nerve [11].
Local anesthetics for reducing pain Decreases the high costs of anti-inflammatory drugs, opioids and infusion pumps. Local infiltration of bupivacaine is a known method of postoperative pain reduction in many other surgical specialties effective in some [12,13], noneffective in others [14,15]. Combination of long acting anesthetic agent and corticosteroid can reduce postoperative discomfort [16]. As there are limited numbers of such studies in our country, we decided to perform the study to see whether it could lead to better pain control or not.
Matrials and Methods
This is a double blind randomized clinical trial performed on 50 patients with disc herniation and canal stenosis, referring to Rajaee hospital, Qazvin (2019), to evaluate the effects of local injection of bupivacaine in reducing postoperative pain. This study approved by ethical committee of Qazvin University of Medical Sciences with ethical number of IR.QUMS.REC.1395.119.
There is no conflict with ethical considerations. Also, the research protocol was approved by the Iranian Registry of Clinical Trials (IRCT2017020625676N8). After signing the personal testimonial papers of participating in the clinical trial, 50 patients (class ASA I and II) randomly entered in groups: interventional and control. The interventional group (25 patients) was injected sub dermal and intramuscular bupivacaine and the control group (25 patients) received only normal saline in the same way. Addicted patients and those with surgery duration more than 2.5 hours were omitted from the study. At the end of operation in the interventional group, bupivacaine 0.25% and in the control group, 40 ml normal saline were infiltrated subdermally and intramuscularly while the surgeon and educated nurse were not aware of the type of drugs injected. Before surgery, the patients were educated to use VAS (visual analogue scale) to point their postoperative pain severity. Pain severity was registered at hours 3, 12 and 24 by educated personnel (either nurse or physician). For those patients with VAS≥4 morphine was injected intravenously and the dose used were documented in the clinical dossier.
Statistical method
Kai score was used for qualitative factors analysis, T-test two independent samples, for quantitative factors and repetitive measures in SPSS-22 software was used for evaluation of pain intensity during different periods of time.
Results
Information of 50 patients were analyzed. 26 (52%) received bupivacaine and 24(48%) received normal saline. In bupivacaine group the average age was 43.62±11.41 and in saline group was 44.54±15.25. Age range of patients was 25-72 years. 11 men (45.8%) and 15 women (57.7%) received bupivacaine. 13 men (54.2%) and 11 women (42.3%) received saline. There was no significant difference in regard to age (P= o.191) and gender (P= 0.290) between the two groups. Other patient characteristics are shown in Table 1.
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