Intravenous Regional Anesthesia: A Historical Overview and Clinical Review

Comparison of nerve block and spinal anesthesia in second toe pulp free flap surgery for fingertip reconstruction

Toe pulp flap surgery is a viable option for soft tissue defects of the fingertips, effectively addressing patient needs and fingertip characteristics. The preferred anesthesia for lower-extremity surgery includes spinal and regional anesthesia. However, the choice between these methods depends on patient safety and surgical efficacy. In this retrospective study, we aimed to ascertain the optimal anesthetic technique by examining the efficacy, safety, pain control, and potential side effects of spinal and peripheral nerve block anesthetics. We included 40 patients aged 18-60 years who underwent partial second toe pulp free flap surgery for fingertip reconstruction. Twenty patients received spinal anesthesia (SA), while the remaining 20 received peripheral nerve block anesthesia. We conducted a comparative analysis of postoperative pain scores, adverse effects, analgesic usage, and patient satisfaction scores associated with each anesthesia method. Independent t-test, Mann-Whitney U test, and chi-squared test were performed. The SA group exhibited hypotension, bradycardia, urinary retention, and postdural puncture headache rates of 10%, 10%, 5%, and 5%, respectively. A significant difference in the timing of first analgesic use was observed (spinal, 3.7 ± 0.8 vs. peripheral nerve block, 13.2 ± 6.6; P = 0.006). Visual analog scale (VAS) scores of the patients at the 2nd, 4th, and 6th h were significantly lower in the peripheral nerve block group (P < 0.001, P < 0.001, P < 0.001, respectively). VAS scores at 12 and 24 h were similar between the groups (P = 0.07, P = 0.135, respectively). Peripheral nerve block anesthesia is superior to SA for partial second toe pulp free flap surgery, offering lower complication rates, reduced postoperative pain, and improved patient comfort.

Regional versus systemic dexmedetomidine as an adjuvant to lidocaine for intravenous regional anaesthesia in healthy volunteers: a randomized crossover study

BACKGROUND

Dexmedetomidine enhances the quality and duration of lidocaine intravenous regional anaesthesia (IVRA). However, the two administration routes have not been directly compared regarding effects on tourniquet tolerance time with lidocaine IVRA. Additionally, it remains unclear whether the prolonged tourniquet tolerance stems from the direct peripheral action of dexmedetomidine or indirect systemic analgesic effects.

METHODS

We conducted forearm IVRA in 12 healthy volunteers using a crossover design on two separate study days. One day, the systemic dexmedetomidine group received an intravenous infusion of 0.5 μg/kg dexmedetomidine (20 mL) in one arm, followed by 0.5% lidocaine (25 mL) forearm IVRA in the contralateral arm. On the other day, the regional dexmedetomidine group received an intravenous 0.9% saline infusion (20 mL) in one arm, followed by combined 0.5% lidocaine (25 mL) and 0.5 μg/kg dexmedetomidine forearm IVRA in the opposite arm. After a two-week washout period, participants crossed over to receive the alternate treatment. The primary outcome was tourniquet tolerance time, from initiating IVRA until the patient-reported tourniquet pain numerical rating scale exceeded three.

RESULTS

The tourniquet tolerance time was longer with regional versus systemic dexmedetomidine (36.9 ± 7.6 min vs 23.3 ± 6.2 min, respectively), with a 13.6 min mean difference (95% CI: 10.8 to 16.4 min, p < 0.001). Regional dexmedetomidine also hastened sensory onset and extended sensory recovery compared to systemic administration. Delayed sedation after tourniquet release occurred in 5 of 12 subjects receiving regional dexmedetomidine.

CONCLUSION

The addition of regional dexmedetomidine to lidocaine prolonged tourniquet tolerance time in forearm IVRA to a greater extent compared to systemic dexmedetomidine in healthy volunteers.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, ChiCTR2300067978.

Regional anaesthesia for ambulatory surgery

Regional anaesthesia (RA) has an important and ever-expanding role in ambulatory surgery. Specific practices vary depending on the preferences and resources of the anaesthesia team and hospital setting. It is used for various purposes, including as primary anaesthetic technique for surgery but also as postoperative analgesic modality. The limited duration of action of currently available local anaesthetics limits their application in postoperative pain control and enhanced recovery. The search for the holy grail of regional anaesthetics continues. Current evidence suggests that a peripheral nerve block performed with long-acting local anaesthetics in combination with intravenous or perineural dexamethasone gives the longest and most optimal sensory block. In this review, we outline some possible blocks for ambulatory surgery and additives to perform RA. Moreover, we give an update on local anaesthesia drugs and adjuvants, paediatric RA in ambulatory care and discuss the impact of RA by COVID-19.

Drug Permeability: From the Blood-Brain Barrier to the Peripheral Nerve Barriers

Drug delivery into the peripheral nerves and nerve roots has important implications for effective local anesthesia and treatment of peripheral neuropathies and chronic neuropathic pain. Similar to drugs that need to cross the blood-brain barrier (BBB) and blood-spinal cord barrier (BSCB) to gain access to the central nervous system (CNS), drugs must cross the peripheral nerve barriers (PNB), formed by the perineurium and blood-nerve barrier (BNB) to modulate peripheral axons. Despite significant progress made to develop effective strategies to enhance BBB permeability in therapeutic drug design, efforts to enhance drug permeability and retention in peripheral nerves and nerve roots are relatively understudied. Guided by knowledge describing structural, molecular and functional similarities between restrictive neural barriers in the CNS and peripheral nervous system (PNS), we hypothesize that certain CNS drug delivery strategies are adaptable for peripheral nerve drug delivery. In this review, we describe the molecular, structural and functional similarities and differences between the BBB and PNB, summarize and compare existing CNS and peripheral nerve drug delivery strategies, and discuss the potential application of selected CNS delivery strategies to improve efficacious drug entry for peripheral nerve disorders.