Continuous Serratus Anterior Blockade for Sternotomy

With the patient in supine position, an ultrasound transducer will be used to find the 4th rib in the mid-axillary line. A 17g touhy needle will be introduced in-plane in an inferior to superior direction until its tip rests between the serratus anterior muscle and the 4th rib or the 3rd external intercostal muscle. A bolus of study drug 10ml (either ropivacaine 0.2% or normal saline) will be delivered though the needle. A 18g multiholed catheter will be inserted and secured to the patients' skin with adhesive dressings. A further 10ml of study drug will be administered through the catheter. The same procedure will be followed on the contralateral side. The study drug will be administered by programmed intermittent bolus (PIB) 10ml every 2 hours to each side in a staggered, alternating fashion. The PIB study drug will to be continued for 72 hours post-insertion.

Patients in both groups will receive the standard of care analgesic medications in the cardiovascular intensive care unit and the ward.