الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Shoulder surgery is the second most frequently performed orthopedic procedure, after knee surgery. Repairing a damaged, degenerated or diseased shoulder joint and treating a variety of diseases and conditions in the shoulder joint. The standard anesthesia in shoulder surgeries is Brachial plexus block, as it ensures proper postoperative pain management that may require large opioids dose, it also facilitates rehabilitation. In upper limb surgeries, it is a method of regional aneshtesia that may be used alone or complementary to general anethisa. It is done by injecting local anesthetic agents close to the brachial plexus. The patient may choose to be concsious or sedated or fully anesthetized if needed. The nerves in the upper limb are easily accessible in several regions and grouped around arteries, making it an ideal location for regional anesthesia. Brachial plexus block temporarily blocks sensation and movement in the upper extremity.
The brachial plexus can be numbed in different methods, depending on where the needle or catheter is inserted to deliver the local anesthetic. It includes the interscalene block (ISB), that is done on the neck, axillary block that is done in the armpit, supraclavicular block above the clavicle, while below the clavicle, the infraclavicular block can be delivered. For the shoulder and proximal upper extremity, ISB is chosen. While for mid-humerus and below, the supraclavicular block is the best. Axillary blocks is used in forearm surgeries. If continuous anesthesia is required, Infraclavicular block is chosen.
The principal indication for an ISB is surgery of the shoulder. Local anesthetic spread after interscalene administration extends from the distal roots/proximal trunks, and follows a distribution to the upper dermatomes of the brachial plexus and its upper trunk. ISB under US guidance may help to improve the accuracy of placement and reduce the risk of complications. As individual nerves can be more easily located, which allows for the use of smaller volumes of anesthetic and consequently reduce risk of local anesthesia spread to the phrenic nerve. Possible complications of ISB include arterial puncture, pneumothorax, and diaphragmatic dysfunction.
The primary aim of this study was to compare between the low dose and high dose Bupivacaine in phrenic nerve affection in interscalene nerve block. The secondary aim was to study the efficacy of ultrasound guided interscalene nerve block on the intensity of postoperative pain.
Included patients were classified as American Society of Anesthesiologists physical status I- II, with a Body mass index of 18-35 kg.m-2. Patients randomly received either low dose bupivacaine (5ml; 0.5%) or high dose bupivacaine (10ml; 0.5%) in ultrasound-guided ISB. The two groups were compared against each other in terms of efficacy and safety up to 12 hours post-operatively.
Regarding demographics, there were no significant differences in the gender distribution between the two study arms (p-value: 0.82). However, the recruited cases had a significantly higher mean age (40 years) compared to the control subjects (35 years; p-value: 0.016). In terms of vital signs, the cases had significantly higher intraoperative and postoperative heart rates (HR) compared to the controls. The postoperative mean arterial blood pressure (ABP) was also significantly higher in the cases compared to the controls (p-value: <0.001).
Pain severity, assessed using the visual analogue scale (VAS), showed a gradual increase from 30 minutes postoperatively to 6 hours postoperatively, followed by a slight decrease. Overall, the cases (low dose group) reported higher mean pain severity compared to the controls (high dose group). The cases requested postoperative analgesics significantly earlier than the controls (p-value: <0.001). Complications were rare, with no cases of paradoxical abdominal movement, residual neuromuscular block, or diaphragmatic excursion, except for one case. The majority of participants required postoperative analgesics, with no significant difference between the two study arms. In the correlation analysis, mean pain severity was found to be significantly correlated with older age and intraoperative HR. However, these correlations were not significant when analyzed separately for cases and controls.
A multivariable regression analysis was performed to investigate the difference in mean pain severity between the cases and controls while considering age and intraoperative HR as potential confounders. The analysis revealed that the difference in mean pain severity between the two groups was no longer significant after adjusting for age and intraoperative HR. Instead, mean intraoperative HR was found to be significantly associated with postoperative pain severity (p-value: <0.001). The findings suggest that the initial differences in pain severity between the cases and controls were likely influenced by age and intraoperative HR, rather than the intervention itself. Therefore, it is crucial to consider these potential confounding variables when interpreting study results.
The results highlight the importance of individualized pain management strategies based on patient characteristics and monitoring of intraoperative HR to optimize postoperative pain control. Our findings were in-line with numerous previously published results. However, the comparison done at the current study is unprecedented and the findings did address the knowledge gap found in the literature.