The use of regional nerve blocks in the management of perioperative pain has gained popularity in recent years. Also referred to as “preventive analgesia,” regional nerve blocks are a safe and effective method of pain management, where the blockade of specific nerves can lead to a reduction in postoperative pain and opioid consumption [1,2]. The timing of regional nerve block is an important consideration for proper analgesia.
During surgery, nociceptive signals initiated by tissue injury induce a state of central nervous system hyperactivity which causes patients to experience pain [3]. This central sensitization is thought to be the underlying mechanism of persistent postoperative pain [3]. Failure to control postoperative pain has been associated with prolonged hospital stays, increased healthcare costs, weakening of the immune system, and development of chronic pain [5]. The two main modalities of regional nerve blocks, single-shot and continuous, have both been shown to be a successful methods of controlling postoperative pain, specifically pain associated with mobilization, which is commonly the most difficult pain to alleviate [3].
One factor that influences the timing of the regional nerve block is the type of nerve block being used [2,4]. Continuous nerve blocks delivered through an indwelling catheter have been shown to have a small but significant advantage over single-shot nerve blocks in controlled postoperative pain in some studies [5]. A 2022 study comparing the benefits of a single-shot femoral nerve block versus a continuous femoral nerve block found that patients who received the former had a 50% reduction in the need for postoperative manipulation after total knee arthroplasty [5]. However, the superiority of continuous versus single-shot nerve blocks in pain management remains debated [5].
Another factor that influences the timing of the regional nerve block is the type of surgery being performed [2,4]. In upper limb surgeries, a continuous brachial plexus block (CIBPB) is often given before or after the induction of anesthesia [4]. Some institutions have even beguan to explore initiating CIBPB postoperatively for pain control, although no significant difference between preoperatively initiated CIBPB and postoperatively initiated CIBPB was measured [4]. The choice of timing depends on the anesthesiologist’s preference, patient clinical status, and the surgery being performed [4]. In contrast, for lower limb surgeries, a femoral nerve block is typically administered after the induction of anesthesia due to the anatomical location of the nerve under the inguinal canal and discomfort that patients can experience if the block is performed while they are awake [5].
Furthermore, the timing of regional nerve block administration before surgery remains an area of controversy partially due to concerns about rebound pain when the effects of the block wear off [2]. The phenomenon of rebound pain has only started to be explored in recent literature [2]. A 2017 study sought to explore this concept by interviewing patients who received a peripheral nerve block before ankle surgery [2]. All patients received a single-shot popliteal sciatic and saphenous nerve block as primary anesthesia using ropivacaine 0.75% [2]. Patients were told to expect a minimal block duration of 12 hours [2]. The results of the study found that most patients generally expressed satisfaction with the peripheral nerve block regardless of their postoperative pain profile [2]. Mental alertness, increased mobility, and the ability to eat without nausea were advantages emphasized in patient interviews [2]. Some did experience “excruciating” pain when the single-shot block wore off, and it appears that nocturnal cessation of the blocks’ effect worsened the issue [2].
Given the current lack of consensus on the ideal timing of regional nerve block administration, anesthesiologists should use evidence-based clinical judgement and patient preference to make decisions on whether to administer a nerve block before or after induction of anesthesia, and whether to use a single-shot or continuous mode of analgesia. Further research is needed to establish the optimal timing of regional nerve blocks.
References
- Richebé, P., Rivat, C., & Liu, S. (2013). Perioperative or postoperative nerve block for preventive analgesia: should we care about the timing of our regional anesthesia?. Anesthesia & Analgesia, 116(5), 969-970.
- Henningsen, M., Sort, R., Møller, A., & Herling, S. (2018). Peripheral nerve block in ankle fracture surgery: a qualitative study of patients’ experiences. Anaesthesia, 73(1), 49-58.
- Lavand’homme, P. (2011). From preemptive to preventive analgesia: time to reconsider the role of perioperative peripheral nerve blocks?. Regional Anesthesia and Pain Medicine, 36(1), 4-6.
- Kim, H. J., Kim, H., Koh, K. et al. (2022). Initiation Timing of Continuous Interscalene Brachial Plexus Blocks in Patients Undergoing Shoulder Arthroplasty: A Retrospective Before-and-After Study. Journal of Personalized Medicine, 12(5), 739.
- Freccero, D., Van Steyn, P., Joslin, P. et al. (2022). Continuous Femoral Nerve Block Reduces the Need for Manipulation Following Total Knee Arthroplasty. JBJS Open Access, 7(3).