The median effective analgesic dose (ED50) of ropivacaine in ultrasound-guided transversus abdominis plane block for analgesia in reversal of ileostomy: A double-blind up-down dose-finding study

Ultrasound-Guided Rectus Sheath Block Combined with Butorphanol for Single-Incision Laparoscopic Cholecystectomy: What is the Optimal Dose of Ropivacaine?

Purpose

In recent years, ultrasound-guided rectus sheath block (RSB) has been widely used in postoperative analgesia of abdominal operation. However, there is no uniform standard for the optimal dose of local anesthetics (LA) under ultrasound-guided rectus sheath block. This study aimed to determine the dose of ropivacaine combined with butorphanol that is effective in 50% (ED50) and 95% (ED95) of subjects for successful pain-free ultrasound-guided RSB in single-incision laparoscopic cholecystectomy (SILC).

Patients and Methods

Twenty-four patients scheduled to undergo single-incision laparoscopic cholecystectomy received an ultrasound-guided RSB. The initial dose of ropivacaine injected was 1.7 mg/kg, which was subsequently increased or decreased by 0.2 mg/kg, depending on whether the previous patient was free from pain (numeric rating scale (NRS) score of incisional pain at rest within 12 h after operation ≤ 3). All patients were treated with butorphanol 0.02 mg/kg as preemptive analgesia. The ED50 and ED95 were calculated using a probit regression model.

Results

The ED50 and ED95 of ropivacaine combined with butorphanol in ultrasound-guided rectus sheath block for analgesia in SILC, which were calculated by the probit regression model, were 0.719 mg/kg (95% confidence interval (CI), 0.553 mg/kg−0.873 mg/kg) and 0.967 mg/kg (95% CI, 0.835 mg/kg−1.91 mg/kg), respectively.

Conclusion

As part of a multimodal analgesia strategy, a dose of 0.719 mg/kg ropivacaine provided successful RSB under ultrasound guidance in 50% of the patients who underwent SILC. A dose of 0.967 mg/kg would be successful in 95% of patients.

Transversus Abdominis Plane Block

In this narrative review article, the authors discuss the anatomy, nomenclature, history, approaches (posterior vs. lateral vs. subcostal), techniques, pharmacology, indications, and complications of transversus abdominis plane blocks, as well as possible alternative truncal blocks.

Despite the scarcity of evidence and contradictory findings, certain clinical suggestions can nonetheless be made. Overall transversus abdominis plane blocks appear most beneficial in the setting of open appendectomy (posterior or lateral approach). Lateral transversus abdominis plane blocks are not suggested for laparoscopic hysterectomy, laparoscopic appendectomy, or open prostatectomy. However, transversus abdominis plane blocks could serve as an analgesic option for Cesarean delivery (posterior or lateral approach) and open colorectal section (subcostal or lateral approach) if there exist contraindications to intrathecal morphine and thoracic epidural analgesia, respectively.

Future investigation is required to compare posterior and subcostal transversus abdominis plane blocks in clinical settings. Furthermore, posterior transversus abdominis plane blocks should be investigated for surgical interventions in which their lateral counterparts have proven not to be beneficial (e.g., laparoscopic hysterectomy/appendectomy, open prostatectomy). More importantly, because posterior transversus abdominis plane blocks can purportedly provide sympathetic blockade and visceral analgesia, they should be compared with thoracic epidural analgesia for open colorectal surgery. Finally, transversus abdominis plane blocks should be compared with newer truncal blocks (e.g., erector spinae plane and quadratus lumborum blocks) with well-designed and adequately powered trials.

Endogenous Opiates and Behavior: 2016

This paper is the thirty-ninth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2016 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia, stress and social status, tolerance and dependence, learning and memory, eating and drinking, drug abuse and alcohol, sexual activity and hormones, pregnancy, development and endocrinology, mental illness and mood, seizures and neurologic disorders, electrical-related activity and neurophysiology, general activity and locomotion, gastrointestinal, renal and hepatic functions, cardiovascular responses, respiration and thermoregulation, and immunological responses.

Levobupivacaine absorption pharmacokinetics with and without epinephrine during TAP block: analysis of doses based on the associated risk of local anaesthetic toxicity

PURPOSE

Cases of local anaesthetic systemic toxicity (LAST) periodically occur following transversus abdominal plane (TAP) blocks. The aim of this study was to characterize levobupivacaine absorption pharmacokinetics, with and without epinephrine, and estimate the risk of LAST, based on a previously reported toxic threshold.

METHODS

Previously reported data from 11 volunteers receiving ultrasound-guided TAP blocks with and without epinephrine on two independent occasions were analysed. Serial venous concentrations were measured for 90 min. A pharmacokinetic analysis was performed using the NONMEM statistical programme. The use of epinephrine in the solution was included in the analysis of covariates. The associated risk of LAST symptoms associated with different levobupivacaine dose schemes with and without epinephrine was estimated in 1000 simulated subjects.

RESULTS

A one-compartment first-order input and elimination model adequately fit the levobupivacaine data. Epinephrine prolonged the levobupivacaine absorption half-life {4.22 [95 % confidence interval (CI) 2.53-6.50] vs. 7.02 [95 % CI 3.74-14.1]; p < 0.05} and reduced its relative bioavailability (0.84; 95 % CI 0.72-0.97; p < 0.05) The derived model predicts that levobupivacaine dose schemes should be halved from 3 mg kg(-1) body weight with epinephrine to 1.5 mg kg(-1) without epinephrine to obtain a comparable risk of anaesthetic toxicity symptoms of approximately 0.1 %.

CONCLUSIONS

Our results strongly support the addition of epinephrine to the local anaesthetic solution, especially when doses of levobupivacaine of >1.5 mg kg(-1) are required. Recommendations regarding the maximum allowable doses of local anaesthetics should consider population analysis to determine safer dosage ranges.