The International Association for the Study of Pain (IASP) defines pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage”.

Post-operative pain is a problem for many patients and affects recovery, risk of post-operative complications and quality of life. A thorough preoperative evaluation, careful perioperative planning, identification, and individualized treatment of high-risk patients can reduce post-operative pain. Multimodal treatment combines different analgesic techniques in order to utilize synergistic and additive effects of different treatments and has the potential to optimize effects and reduce side effects.

Currently, various modalities for post-operative pain management exist. Traditionally opioids ,NSAIDS and Paracetamol were used as the main agents for post-operative analgesia.Newer modalities include Patient Control Analgesia (PCA) pumps, epidural neuraxial blocks and peripheral nerve blocks. With multimodal approach there is decrease in opioid requirement and at the same time reduction in side effects due to opioids such as nausea, vomiting, drowsiness and constipation.

There is an increasing trend toward the use of peripheral nerve blocks for post-operative pain control. They are one of the safest and most effective methods to control pain from surgery.For post- operative pain control nerve blocks can be given alone or as a component of multimodal analgesia. In a peripheral nerve block, anaesthetic drug is injected at a particular site around the nerves which then stop the pain signal to reach the brain, thus provides analgesia. Peripheral nerve block can be given as a single injection (sPNB), when post-operative pain is of short duration or as a continuous catheter infusion (cPNB), when prolonged post-operative analgesia is required .

Uncontrolled pain after abdominal surgery increases the incidence of postoperative complications, as it prolongs hospitalization, and increases health care costs and the use of opioids.Interfacial plane blocks such as Quadratus Lumborum block (QLB) and Errector Spinae block are the new emerging modalities, performed by ultrasound guidance, that are being put to use for post operative analgesia in patients undergoing abdominal surgeries.

Quadratus lumborum block has been used for postoperative analgesia in patients undergoing upper abdominal surgeries. The analgesia is achieved in T7–L1 dermatomes,with cranial spread to T4–T5 and caudal spread to L2–L3 dermatomes. Quadratus lumborum block 3 implies the application of the local anesthetic between the QLM and the psoas major muscle (PMM) at the front of the QLM, at the level of its attachment to the transverse process of L4 vertebra.

Erector spinae block (ESB) is an interfascial plane block in which anaesthetic drug is injected between anterior surface of Erector spinae muscle and transverse process of underlying vertebra. It acts by blocking dorsal and ventral rami of spinal nerves .Block will be performed at the T9 level in our study.

Ropivacaine is a long-acting amide local anaesthetic agent and first produced as a pure enantiomer .It produces effects similar to other local anaesthetics via reversible inhibition of sodium ion influx in nerve fibres. Ropivacaine is less lipophilic than bupivacaine and is less likely to penetrate large myelinated motor fibres, resulting in a relatively reduced motor blockade.Thus, ropivacaine has a greater degree of motor sensory differentiation, which could be useful when motor blockade is undesirable. The reduced lipophilicity is also associated with decreased potential for central nervous system toxicity and cardiotoxicity.

Patient controlled analgesia (PCA) is another modality which is given along with    peripheral nerve blocks to reduce post-operative pain. PCA allow patient to control his desired level of analgesia which ultimately lead to patient satisfaction .

The above mentioned nerve blocks have been studied and used in the management of postoperative pain in patients undergoing upper abdominal surgeries with variable results. So, in this study we will be comparing the effectiveness of Quadratus lumborum block and Erector spinae plane block along with PCA for post-operative pain management in abdominal surgeries with midline incision.

Sample Size:

n= (Z²_a/2 p(1-p)

              d²

^Z _α/2 = 1.96 at 5% level of significance

p = prevalence

Here, we conside p=50%

p=505=0.5

1-p=1-0.5=0.5

d=adsolute pricisim

d=12%=0.12

n= (1.96)²x(0.5)x(0.5)

              (0.12)²

n= 3.84x0.25

        0.0144

n=66.66

n = 67

So, the sample size is 67.