Rectus sheath single-injection blocks: a study to quantify local anaesthetic absorption using serial ultrasound measurements and lidocaine serum concentrations

Abstract

Objectives Rectus sheath blocks are an established option for analgesia following abdominal surgery, but pharmacokinetic data are limited. This study sought to characterise the absorption of lidocaine injectate and the pharmacokinetics of lidocaine after rectus sheath injection. Methods Bilateral rectus sheath single‐injection blocks were given to 10 patients undergoing general or urological surgery. Afterwards, serial lidocaine serum levels and ultrasound measurements of the rectus sheath injectate reservoir were collected. Key findings Injectate within the rectus sheath was visible with ultrasound up to 12 h after injection. However, the rate of drug absorption exceeded that of injectate disappearance. Peak serum concentration occurred within 30 min with average peak concentrations of 1.65 μg/ml. Lidocaine clearance was lower than reported in young healthy subjects. The body mass index positively correlated with lidocaine terminal phase half‐life, and clearance negatively correlated with age. Conclusions The study provides the first data describing lidocaine pharmacokinetics after rectus sheath injection. Peak serum concentrations transiently achieved systemic levels associated with pain relief after a single bolus injection. The data from this study could be used to develop a regime using single shot rectus sheath blockade with a bolus of lidocaine followed by infusion using bilateral rectus sheath catheters.

Effect of Stellate Ganglion Block Combined with Lidocaine at Different Concentrations for Preemptive Analgesia on Postoperative Pain Relief and Adverse Reactions of Patients Undergoing Laparoscopic Cholecystectomy

“…In addition, the stellate ganglion is a cervical sympathetic ganglion, which is merged by the inferior cervical ganglion from C 3-7 with the first thoracic sympathetic ganglion and sometimes including T 2 and middle cervical ganglia. Relevant published works have pointed out that SGB can improve patient tolerance to surgical trauma and ensure perioperative safety and treatment efficacy [ 17 ]. The indications for SGB are broad, including systemic disorders (myasthenia gravis), head disorders (cerebral vascular spasm), and eye disorders (cataracts).…”

Effects of pecto-intercostal fascial block combined with rectus sheath block for postoperative pain management after cardiac surgery: a randomized controlled trial

“…[18] And RSB even a single shot seems to have a sustained and extended analgesia pharmacokinetically. [19] Drainage pain is severe and persistent, the application of RSB could solve this problem, reducing nearly 35% opioid consumption. There was no signi cant difference in the incidence of pain at the chest tube within 48h (14.8% vs 29.6%, p = 0.190), merely a higher trend in the PIFB group.…”

Piecing together human adult comparative pharmacokinetic trials and rodent studies: What happens to drug clearance in obesity?

“…Similarly, in rats fed HFD, the intrinsic CL of lidocaine to its main dealkylated metabolite was decreased (96). In surgical patients given lidocaine as rectus sheath injection (139), the correlation of weight-unadjusted lidocaine plasma CL was weak and not significant (r=-0.22, p>0.05). However, when viewed as weight-normalized CL, there was a significant negative correlation of plasma CL with BMI (r =-0.85, p<0.05).…”