Continuous Transversus Abdominis Plane Nerve Blocks: Does Varying Local Anesthetic Delivery Method—Automatic Repeated Bolus Versus Continuous Basal Infusion—Influence the Extent of Sensation to Cold?: A Randomized, Triple-Masked, Crossover Study in Volunteers

Abstract

Background It remains unknown whether continuous or scheduled intermittent bolus local anesthetic administration is preferable for transversus abdominis plane (TAP) catheters. We therefore tested the hypothesis that when using TAP catheters, providing local anesthetic in repeated bolus doses increases the cephalad-caudad cutaneous effects compared with a basal-only infusion. Methods Bilateral TAP catheters (posterior approach) were inserted in 24 healthy volunteers followed by ropivacaine 2 mg/mL administration for a total of 6 hours. The right side was randomly assigned to either a basal infusion (8 mL/h) or bolus doses (24 mL administered every 3 hours for a total of 2 bolus doses) in a double-masked manner. The left side received the alternate treatment. The primary endpoint was the extent of sensory deficit as measured by cool roller along the axillary line at Hour 6 (6 hours after the local anesthetic administration was initiated). Secondary endpoints included the extent of sensory deficit as measured by cool roller and Von Frey filaments along the axillary line and along a transverse line at the level of the anterior superior iliac spine at Hours 0–6. Results While there were statistically significant differences between treatments within the earlier part of the administration period, by Hour 6 the difference in extent of sensory deficit to cold failed to reach statistical significance along the axillary line (mean=0.9 cm; SD=6.8; 95% CI −2.0, 3.8; p=0.515) and transverse line (mean=2.5 cm; SD=10.1; 95% CI −1.8, 6.8; p=0.244). While the difference between treatments was statistically significant at various early time points for the horizontal, vertical and estimated area measurements of both cold and mechanical pressure sensory deficits, no comparison remained statistically significant by Hour 6. Conclusion No evidence was found in this study involving healthy volunteers to support the hypothesis that changing the local anesthetic administration technique (continuous basal versus hourly bolus) when using ropivacaine 0.2% and TAP catheter at 8 mL/h and 24 mL every 3 hours significantly influences the cutaneous effects after 6 hours of administration. Additional research is required to determine whether changing variables (e.g., local anesthetic concentration, basal infusion rate, bolus dose volume and/or interval) would provide different results.

Analgesic efficacy of an opioid-free postoperative pain management strategy versus a conventional opioid-based strategy following laparoscopic radical gastrectomy: an open-label, randomized, controlled, non-inferiority trial

“…Studies have shown that there wasno advantage of increasing the local anesthetic drug greater than 20 ml for STAPB [ 25 ]. At present, there are two main methods of administration for C-STAPB: one is low-dose continuous infusion, and the other is repetitive intermittent administration [ 26 , 27 ]. Compared with continuous infusion, an intermittent bolus of ropivacaine was found to not only lessen the overall local anesthetic requirement per day, but also has a wider sensory dermatome blockade and longer duration of analgesia.…”

Basal InfusionversusAutomated Boluses and a Delayed Start Timer for “Continuous” Sciatic Nerve Blocks after Ambulatory Foot and Ankle Surgery: A Randomized Clinical Trial

“…Our study is unique relative to nearly all previous investigations comparing automated boluses to a basal infusion in that (1) we included an integrated start-delay timer; (2) we did not define a maximum treatment period but rather removed catheters only after reservoir exhaustion; (3) we collected data 6 days after surgery, which is two to three times longer than previous investigations; and (4) we decreased mandatory average hourly local anesthetic delivery, while most others compared equivalent volumes/doses. 6–20,30–32…”

“…Our study is unique relative to nearly all previous investigations comparing automated boluses to a basal infusion in that (1) we included an integrated start-delay timer; (2) we did not define a maximum treatment period but rather removed catheters only after reservoir exhaustion; (3) we collected data 6 days after surgery, which is two to three times longer than previous investigations; and (4) we decreased mandatory average hourly local anesthetic delivery, while most others compared equivalent volumes/doses. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][30][31][32] Basal versus Automatic Boluses For popliteal-sciatic catheters after foot and ankle surgery, previous studies suggest that providing a basal infusion maximizes analgesia and other benefits compared with exclusively patient-controlled boluses, presumably due to the observed decrease in anesthetic volume/dose administered when patients must trigger the boluses themselves. 2,33 However, based on findings for epidural catheters, [34][35][36] it was theorized that increasing the volume of local anesthetic introduced at a single time point-a bolus-might improve perineural spread compared with an equivalent volume/dose provided as a basal infusion providing superior analgesia.…”

“…6 To date, nearly all trials involving ultrasound-guided catheter insertion adjacent to various peripheral nerves have failed to detect analgesic superiority of one administration modality over the other with equivalent hourly local anesthetic volume and dose, especially with the addition of patient-controlled boluses. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] While this suggests that switching from basal to automated boluses is unwarranted, 21 if the latter allows for a decrease in hourly anesthetic consumption while providing noninferior analgesia, it could prolong anesthetic administration and therefore analgesia. For outpatients with a fixed-volume reservoir, automated intermittent boluses offer two different opportunities to improve postoperative analgesia: (1) in the few initial postoperative days and (2) after the time when a basal infusion would have exhausted the anesthetic reservoir.…”