High Versus Low Dose Serratus Anterior Plane Block After Minimally Invasive Valve Surgery.

The needle will be introduced in-plane from supero-anterior to postero-inferior until the needle tip is positioned in the plane underneath the serratus muscle (deep compartment). Under continuous ultrasound guidance, 3/4th of the bupivacaine 0.25% plus epinephrine solution will be injected in the deep compartment. After the deep component of the serratus anterior plane block is completed, the needle will be withdrawn to the subcutaneous tissues. The needle will be flattened and advanced in-plane to the plane superficial to the serratus muscles. The remainder quarter of the bupivacaine 0.25% plus epinephrine solution will be injected superficial to the serratus muscles after correct placement of the needle tip is confirmed on ultrasound. In total a dose of 2.4mg/kg patient ideal body weight will be administered. There is a maximal dose of 200 mg adrenalized bupivacaine for patients with an ideal body weight of 83 kg or more.

The needle will be introduced in-plane from supero-anterior to postero-inferior until the needle tip is positioned in the plane underneath the serratus muscle (deep compartment). Under continuous ultrasound guidance, 3/4th of the bupivacaine 0.25% will be injected in the deep compartment. After the deep component of the serratus anterior plane block is completed, the needle will be withdrawn to the subcutaneous tissues. The needle will be flattened and advanced in-plane to the plane superficial to the serratus muscles. The remainder quarter of the bupivacaine 0.25% will be injected superficial to the serratus muscles after correct placement of the needle tip is confirmed on ultrasound.

A patient controlled intravenous analgesia system (Bodyguard 595 Colorvision®) with morphine (Sterop®) using following settings: bolus 1.5 mg and lockout interval 7 min with maximal dose of 30mg per 4 hours.