The Analgesic Efficacy of Intrathecal Bupivacaine and Fentanyl with Added Neostigmine or Magnesium Sulphate

Adjuvant Drugs for Peripheral Nerve Blocks: The Role of NMDA Antagonists, Neostigmine, Epinephrine, and Sodium Bicarbonate

The potential for misuse, overdose, and chronic use has led researchers to look for other methods to decrease opioid consumption in patients with acute and chronic pain states. The use of peripheral nerve blocks for surgery has gained increasing popularity as it minimizes peripheral pain signals from the nociceptors of local tissue sustaining trauma and inflammation from surgery. The individualization of peripheral nerve blocks using adjuvant drugs has the potential to improve patient outcomes and reduce chronic pain. The major limitations of peripheral nerve blocks are their limited duration of action and dose-dependent adverse effects. Adjuvant drugs for peripheral nerve blocks show increasing potential as a solution for postoperative and chronic pain with their synergistic effects to increase the duration of action and decrease the required dosage of local anesthetic. N-methyl-d-aspartate (NMDA) receptor antagonists are a viable option for patients with opioid resistance and neuropathic pain due to their affinity to the neurotransmitter glutamate, which is released when patients experience a noxious stimulus. Neostigmine is a cholinesterase inhibitor that exerts its effect by competitively binding at the active site of acetylcholinesterase, which prevents the hydrolysis of acetylcholine and subsequently retaining acetylcholine at the nerve terminal. Epinephrine, also known as adrenaline, can potentially be used as an adjuvant to accelerate and prolong analgesic effects in digital nerve blocks. The theorized role of sodium bicarbonate in local anesthetic preparations is to increase the pH of the anesthetic. The resulting alkaline solution enables the anesthetic to more readily exist in its un-ionized form, which more efficiently crosses lipid membranes of peripheral nerves. However, more research is needed to show the efficacy of these adjuvants for nerve block prolongation as studies have been either mixed or have small sample sizes.

The efficacy of spinal anaesthesia with fentanyl supplementation for arthroscopic knee surgery: A meta-analysis of randomized controlled studies

INTRODUCTION

The efficacy of spinal anaesthesia with fentanyl supplementation for arthroscopic knee surgery remains controversial. We conducted a systematic review and meta-analysis to explore the influence of fentanyl supplementation for arthroscopic knee surgery.

METHODS

We searched PubMed, Embase, Web of Science, EBSCO and Cochrane Library databases through May 2019 for randomized controlled trials (RCTs) assessing the efficacy and safety of fentanyl supplementation for arthroscopic knee surgery. This meta-analysis is performed using the random-effects model.

RESULTS

Five RCTs are included in the meta-analysis. Overall, compared with the control group for knee arthroscopy, fentanyl supplementation is associated with decreased time for sensory block regression to S1 (mean difference (MD) = -47.38; 95% confidence interval (CI) = -56.74 to -38.02; p < 0.00001), first ambulation (MD = -41.65; 95% CI = -65.11 to -18.19; p = 0.0005), first urination (MD = -23.45; 95% CI = -32.16 to -14.74; p < 0.00001) and hospital discharge (MD = -29.39; 95% CI = -44.73 to -14.06; p = 0.0002) but has no substantial influence on onset time of anaesthesia (MD = 0.50; 95% CI = -1.71 to 2.70; p = 0.66), duration for motor blockade (MD = -42.56; 95% CI = -119.18 to 34.07; p = 0.28), pruritus (risk ratio (RR) = 2.17; 95% CI = 0.28 to 16.90; p = 0.46) or nausea (RR = 0.42; 95% CI = 0.10 to 1.81; p = 0.25).

CONCLUSIONS

Fentanyl supplementation benefits postoperative recovery after knee arthroscopy.