Plasma Concentrations of Levobupivacaine With and Without Epinephrine in Transversus Abdominis Plane Blocks

The subjects were randomized to receive a unilateral TAP block. This was realized using a sterile technique, guided by ultrasound. Two operators with experience in ultrasound-guided regional blocks performed all procedures. A high-resolution linear U.S. transducer (L38x/10-5 MHz Sonosite M-Turbo®, Bothell, WA) and a Stimuplex 100 mm needle, 20 gauge (B. Braun Stimuplex, Melgusen, Germany) were used. After obtaining a clear view of the blocking plane, between internal oblique and transverse muscles, 20 ml of levobupivacaine 0.25% with 5 µg/mL epinephrine were injected.

The subjects were randomized to receive a unilateral TAP block. This was realized using a sterile technique, guided by ultrasound. Two operators with experience in ultrasound-guided regional blocks performed all procedures. A high-resolution linear U.S. transducer (L38x/10-5 MHz, Sonosite M-Turbo ®, Bothell, WA) and a Stimuplex 100 mm needle, 20 gauge (B. Braun Stimuplex, Melgusen, Germany) were used. After obtaining a clear view of the blocking plane, between internal oblique and transverse muscles, 20 ml of levobupivacaine 0.25% were injected.

Standard anesthetic monitoring was used, including continuous electrocardiogram, non invasive blood pressure and peripheral oxygen saturation. Later, under local anesthesia a permeable venous line and an arterial line were installed for blood sampling measures to determine local anesthetic plasma levels.

The extent of sensory block was measured by assessment of temperature, soft and hard touch using alcohol, cotton and pin prick respectively. These measurements were made every 10 minutes during the first hour and every 30 minutes to complete 4 hours.