COMPARISON OF ULTRASOUND GUIDED RECTUS SHEATH BLOCK AND OBLIQUE SUBCOSTAL TRANSVERSUS ABDOMINIS PLANE BLOCK FOR PERIOPERATIVE ANALGESIA FOR MIDLINE INCISION ABDOMINAL SURGERIES

Intervention1: Rectus sheath block: A USG machine with linear array probe (5-12MHz) with an imaging depth of 4-6cm will be used for performing the block.
The ultrasound probe will be placed transverse on abdomen, immediately lateral (3 cm) to umbilicus.
A 20-gauge needle will be inserted in-plane in a medial to lateral orientation, through the subcutaneous tissue, to pierce through the anterior rectus sheath.
Upon identification of the rectus muscle and hyperechoic twin lines deep to it (posterior rectus sheath and fascia transversalis) in the ultrasound image the needle tip will be advanced to the desired position, posterior to the rectus muscle and above the underlying posterior rectus sheath under direct vision.
Following con�rmation of the correct position of the needle tip with hydro dissection of the rectus muscle away from the posterior rectus by administration of 0.51ml of normal saline; 20ml of 0.25% bupivacaine will be administered for block performance.
The procedure will be repeated on the opposite side.
Intervention2: oblique subcostal Transversus abdominis plane block: A USG linear array probe with high- or an intermediate-frequency linear probe of 35 to 40 mm will provide adequate imaging.
A needle of up to 15 to 20 cm in length , bend into a slight curve will be required , decribed by Hebbard et al .15
The operator will stand on the left side of the patient in the supine position, and both sides are blocked from this position, with the right hand holding the needle and the left hand holding the probe.
To perform the block, the rectus abdominis and underlying transversus abdominis muscles will be identified near the costal margin and xyphoid.
Local anesthetic is injected incrementally in the TAP (hydrodissection) by a needle passing along the obliq
Primary outcome(s): â?¢To assess the analgesic efficacy of rectus sheath block.
â?¢To assess the analgesic efficacy of oblique subcostal TAP block.
â?¢To compare the analgesic efficacy of both blocks.
Timepoint: 24 hrs
Study Design: Randomized, Parallel Group Trial
Method of generating randomization sequence:Coin toss, Lottery, toss of dice, shuffling cards etc Method of allocation concealment:An Open list of random numbers Blinding and masking:Participant and Investigator Blinded

干预1：腹直肌鞘阻滞（Rectus sheath block）：将使用配备线阵探头（5~12MHz）的超声（Ultrasound, USG）机，设置成像深度为4~6cm以实施阻滞操作。
将超声探头横向放置于腹部，紧邻脐部外侧3cm处。
采用20号针头，以平面内技术从内侧向外侧进针，依次穿过皮下组织并穿透腹直肌前鞘。
于超声图像中识别腹直肌及其深面的高回声双线（腹直肌后鞘与腹横筋膜）后，在直视下将针尖推进至目标位置：即腹直肌后方、腹直肌后鞘浅侧。
通过注入0.5~1ml生理盐水实施水分离，使腹直肌与后鞘分离，确认针尖位置正确后，注入20ml 0.25%布比卡因以完成阻滞操作。
上述操作将在对侧重复实施。

干预2：斜肋下腹横肌平面阻滞（oblique subcostal Transversus abdominis plane block, TAP block）：使用高频或中频线阵探头（35~40mm）的超声机可获得良好成像效果。
需使用长度15~20cm、略微弯曲的针头，该操作方案由Hebbard等人[15]提出。
操作者取患者左侧站位（患者取仰卧位），可通过该体位完成双侧阻滞：右手持针，左手握持探头。
实施阻滞时，在肋缘与剑突附近识别腹直肌及深面的腹横肌。
通过沿斜行路径进针，于腹横肌平面（Transversus abdominis plane, TAP）内分次注入局部麻醉药物以实施水分离。

主要结局指标：
• 评估腹直肌鞘阻滞的镇痛效果
• 评估斜肋下腹横肌平面阻滞的镇痛效果
• 对比两种阻滞方式的镇痛效果

时间节点：术后24小时
研究设计：随机平行对照试验
随机序列生成方法：抛硬币、抽签、掷骰子、洗牌等
分配隐藏方法：公开随机数列表
设盲与法：受试者与研究者双盲