Total and free serum Ropivacaine Concentrations for patients receiving Continuous Transversus Abdominis plane block for Postoperative analgesia after abdominal surgery: Pilot Study

This pilot study is checking how safe it is to use a continuous nerve-blocking technique called a transversus abdominis plane (TAP) block to control pain after abdominal surgery. The technique involves injecting a local anaesthetic called ropivacaine into the space between the abdominal muscles to numb the area. The study measures how much of the drug enters the bloodstream over 48 hours and watches for any signs of toxicity (such as heart rhythm changes). You may be eligible if: - You are 18 to 80 years old - You are having elective or emergency abdominal surgery - Your overall health status is reasonably good (ASA score less than 4) - You can speak and understand English adequately You may NOT be eligible if: - You have an allergy to local anaesthetic - You are pregnant - You are taking regular opioid (strong painkiller) or chronic pain medications - You have an abnormal heart tracing (QTc interval above 0.45 seconds for men, 0.47 for women) - You take certain medications affecting drug metabolism (ciprofloxacin or fluvoxamine) - You take medications that affect heart rhythm (such as haloperidol, amiodarone, or sotalol) Talk to your doctor about whether this trial might be right for you.