The goal of this study is to learn about the effectiveness of TAP block for pain relief after vascular surgery on the abdominal aorta.

The main question the investigators are looking to answer is whether the TAP block lowers the dose of opioid required after abdominal aortic surgery.

The surgery on the abdominal aorta requires extended haemodynamic monitoring and is performed under general anaesthesia. After applying general anaesthesia, the patients will receive a TAP block (subcostal approach) before the start of the surgery.

During the procedure the patients will receive both opioid and nonopioid analgesics, as part of the standard perioperative protocol for abdominal aortic surgery.

After the procedure all patients will receive following the standard protocol for pain relief after abdominal aortic surgery - NSAIDs and nonopioid analgesics regularly. All patients will postoperatively receive opioid as a rescue drug as needed (PCA).

Participants will be randomly allocated in two groups, where one group will receive local anaesthetic for the TAP block and the control group will receive normal saline for the TAP block. The anaesthetist, the nurses and doctors in the postoperative care will all be blinded as to the group in which each patient is allocated.

The participants will be followed from surgery until discharge from hospital.

Inclusion Criteria:

• Adult patients admitted for an elective vascular surgery on abdominal aorta that agree and give written consent to be included in the study.

Exclusion Criteria:

• Patients allergic to the drugs we will use in the study, local anaesthetic, nonopioid analgesics, NSAIDs.
• Patients with pain syndromes that are preoperatively already on any kind of chronic pain therapy.
• Patients that will experience surgical complications that requires reoperation will be excluded postoperatively.

Dedicated anaesthetic nurse will prepare the syringes for administering the TAP block for each participant. She will be the only person to know which group each participant has been allocated to. Since local anaesthetic and normal saline have no color the anaesthetist performing the block will be, as will the doctors and nurses in postoperative care, blinded to the group each participant has been allocated to.