Continuous Wound Infiltration of Local Anesthetics in Postoperative Pain Management: Safety, Efficacy and Current Perspectives

Perioperative pain management with regional analgesia techniques for visceral cancer surgery: A systematic review and meta-analysis

STUDY OBJECTIVE

Regional analgesia following visceral cancer surgery might provide an advantage but evidence for best treatment options related to risk-benefit is unclear.

DESIGN

Systematic review of randomized controlled trials (RCT) with meta-analysis and GRADE assessment.

SETTING

Postoperative pain treatment.

PATIENTS

Adult patients undergoing visceral cancer surgery.

INTERVENTIONS

Any kind of peripheral (PRA) or epidural analgesia (EA) with/without systemic analgesia (SA) was compared to SA with or without placebo treatment or any other regional anaesthetic techniques.

MEASUREMENTS

Primary outcome measures were postoperative acute pain intensity at rest and during activity 24 h after surgery, the number of patients with block-related adverse events and postoperative paralytic ileus.

MAIN RESULTS

59 RCTs (4345 participants) were included. EA may reduce pain intensity at rest (mean difference (MD) -1.05; 95% confidence interval (CI): -1.35 to -0.75, low certainty evidence) and during activity 24 h after surgery (MD -1.83; 95% CI: -2.34 to -1.33, very low certainty evidence). PRA likely results in little difference in pain intensity at rest (MD -0.75; 95% CI: -1.20 to -0.31, moderate certainty evidence) and pain during activity (MD -0.93; 95% CI: -1.34 to -0.53, moderate certainty evidence) 24 h after surgery compared to SA. There may be no difference in block-related adverse events (very low certainty evidence) and development of paralytic ileus (very low certainty of evidence) between EA, respectively PRA and SA.

CONCLUSIONS

Following visceral cancer surgery EA may reduce pain intensity. In contrast, PRA had only limited effects on pain intensity at rest and during activity. However, we are uncertain regarding the effect of both techniques on block-related adverse events and paralytic ileus. Further research is required focusing on regional analgesia techniques especially following laparoscopic visceral cancer surgery.

Use of wound infusion catheters for delivery of local anesthetic following standing partial ostectomy of thoracolumbar vertebral spinous processes in horses is not associated with increased surgical site infections

Background

Wound infusion catheters (WICs) have been used in humans and some veterinary species for post-operative local anesthetic administration following a variety of surgical procedures, aiming to reduce post-operative analgesia requirements and improve patient comfort. Benefit in reduction in pain, post-operative analgesia requirements and length of hospital stay are well documented in humans, but use of WICs may not have been widely adopted in veterinary species due to the concern of increased complications, such as dehiscence or surgical site infection (SSI), creating a barrier to their use. This study aimed to evaluate the use of WICs in horses undergoing standing partial ostectomy surgeries, document complications and investigate if the incidence of SSI was equivalent between those horses that did and did not have a WIC.

Methods

Clinical records were searched between January 2010-December 2023 for horses undergoing standing partial ostectomy surgery of thoracolumbar vertebral spinous processes at one institution. Population variables (age, breed, bodyweight), placement of a WIC or not, post-operative complications, analgesia protocols and surgical time were recorded. Horses received up to 0.1 mg kg-1 bupivacaine (0.5 mg mL-1) every 6-8 h via the WIC where one was placed. To compare SSI complication incidence between using or not using a WIC, a proportional independent equivalence test was used.

Results

There were 64 horses included in the final analysis with a WIC placed in 29/64 horses (45.3%) and 35/64 (54.7%) having no WIC placed at surgery. Incidence of short-term SSI was 11.4% (no WIC used) and 13.8% (WIC used), respectively. The difference in proportion of SSI between the presence or absence of a WIC was not significant [-0.024 (90% CI -0.181; 0.133); p = 0.94].

Conclusion

The incidence of SSIs was equivalent between groups whether a WIC was used or not. WICs should be considered as part of a multi-modal analgesic approach in the post-operative period. Further research into local anesthetic dosing and its impact on rescue analgesia requirements and pain-scores is warranted.

Synergistic interaction of guanfacine or dexmedetomidine coadministered with lidocaine for cutaneous analgesia in rats

BACKGROUND

This study examined the cutaneous analgesic effects of lidocaine co-injected with guanfacine and its comparison with dexmedetomidine.

METHODS

Cutaneous analgesic effects are quantified through the blocking effects of the cutaneous trunci muscle reflex against skin pinpricks in rats. The dose-response curves of guanfacine, dexmedetomidine, and lidocaine were constructed and drug-drug interactions were analyzed by the ED50 isobologram.

RESULTS

Subcutaneous injections of guanfacine, dexmedetomidine, and lidocaine produced dose-dependently nociceptive/sensory blockade. On the ED50 (50% effective dose) basis, the potency rankings of the drug are dexmedetomidine (0.09 [0.08-0.11] μmol/kg) > guanfacine (3.98 [2.96-5.34] μmol/kg) > lidocaine (25.40 [23.51-27.44] μmol/kg) (p < 0.01). On their equipotent doses (ED25, ED50, and ED75), the duration of sensory blockade induced by guanfacine or dexmedetomidine was longer than lidocaine's (p < 0.01). Both guanfacine and dexmedetomidine showed synergistic effects with lidocaine.

CONCLUSIONS

We showed that guanfacine elicits dose-dependent cutaneous analgesia when administered subcutaneously. Lidocaine is less potent than guanfacine or dexmedetomidine. Both guanfacine and dexmedetomidine enhance the potency and duration of lidocaine. Better synergistic responses we are getting with guanfacine plus lidocaine.

Lateral Femoral Cutaneous Nerve Block or Wound Infiltration Combined with Pericapsular Nerve Group (PENG) Block for Postoperative Analgesia following Total Hip Arthroplasty through Posterior Approach: A Randomized Controlled Trial

Background: Pericapsular nerve group (PENG) block, although effective for pain management following total hip arthroplasty (THA), does not cover skin analgesia. In this randomized controlled trial, we compared the effectiveness of PENG block combined with lateral femoral cutaneous nerve (LFCN) block or wound infiltration (WI) on postoperative analgesia and functional outcomes. Methods: Fifty patients undergoing posterior-approached THA under spinal anesthesia were randomly allocated to receive LFCN block with 10 mL of 0.5% ropivacaine or WI with 20 mL of 0.5% ropivacaine. In both groups, PENG block was performed by injecting 20 mL of 0.5% ropivacaine. Primary outcomes were static and dynamic pain scores (0-10 numeric rating scale) measured in the first 24 h after surgery. Secondary outcomes included postoperative opioid consumption, functional assessment and length of hospital stay. Results: Postoperative static NRS of patients receiving LFCN was higher than that of patients receiving WI at 6 h but lower at 24 h, with a median (IQR) of 3 (2-4) vs. 2 (1-2) (p < 0.001) and 2 (2-3) vs. 3 (3-4) (p = 0.02), respectively. Static pain scores at 12 h did not show significant differences, with an NRS of 3 (2-4) for WI vs. 3 (3-4) for LFCN (p = 0.94). Dynamic pain and range of movement followed a similar trend. No significant differences were detected in other outcomes. Conclusions: LFCN block was not inferior to WI for postoperative analgesia and functional recovery in association with PENG block during the first postoperative day, although it had worse short-term pain scores. Based on these results, it is reasonable to consider LFCN block as a valid alternative to WI or even a complementary technique added to WI to enhance skin analgesia during the first 24 h after THA. Future studies are expected to confirm this hypothesis and find the best combination between PENG block and other techniques to enhance analgesia after THA.

Sustained release local anesthetics for pain management: relevance and formulation approaches

This review attempted to ascertain the rationale for the formulation of sustained-release local anesthetics and summarize the various formulation approaches designed to date to achieve sustained and localized local analgesic effects. The incidence of pain, which is the concern of patients as well as health care professionals, is increasing due to accidents, surgical procedures, and other diseases. Local anesthetics can be used for the management of moderate to severe acute and chronic pain. They also allow regional analgesia, in situations where the cause and source of the pain are limited to a particular site or region, without the need for loss of consciousness or systemic administration of other analgesics thereby decreasing the risk of potential toxicities. Though they have an interesting antipain efficacy, the short duration of action of local anesthetics makes the need for their multiple injections or opioid adjuvants mandatory. To overcome this problem, different formulations are being designed that help achieve prolonged analgesia with a single dose of administration. Combination with adjuvants, liposomal formulations, lipid-based nanoparticles, thermo-responsive nanogels, microspheres, microcapsules, complexation with multivalent counterions and HP-β-CD, lipid-based nanoparticles, and bio-adhesive films, and polymeric matrices are among the approaches. Further safety studies are required to ensure the safe and effective utilization of sustained-release local anesthetics. Moreover, the release kinetics of the various formulations should be adequately established.

To assess the analgesic efficacy of adjuvant magnesium sulfate added with ropivacaine over ropivacaine alone as a continuous infiltration in total abdominal hysterectomy wound: A randomized controlled trial

Background and Aims

Magnesium sulfate (MgSO4) has been demonstrated to have analgesic property in various clinical settings. This study explores if addition of MgSO4 to ropivacaine increases its analgesic efficacy when infiltrated continuously in the postsurgical wound following total abdominal hysterectomy.

Material and Methods

This randomized controlled trial was conducted at a tertiary care referral hospital in New Delhi, India. Fifty-two patients were randomized into two groups to receive the intervention of which 48 were able to complete the study. The first group (n = 26) received 0.25% ropivacaine infiltration and the second group (n = 26) received 0.25% ropivacaine with 5% MgSO4 at the incision site for 48 h postoperatively. Primary objective was to compare the total postoperative opioid (morphine) consumption by the study participants in both the groups and the secondary objectives were pain scores at rest and at movement, patient satisfaction score, and wound quality of life on the 7th postoperative day among the two groups.

Results

Both the groups were comparable in their demographic characteristics. The median morphine consumed at 48 h postoperatively was 16.5 [0-77] mg in the ropivacaine group and 13[1-45] mg in the ropivacaine with MgSO4 group and the difference was statistically insignificant (P = 0.788). There was no statistical difference between the groups with respect to the pain scores, patient satisfaction, or wound quality of life at 7 days.

Conclusion

The addition of MgSO4 to ropivacaine does not confer any additional postoperative analgesic benefits over ropivacaine alone in continuous wound infiltration following total abdominal hysterectomy.

Can Ultrasound-Guided Continuous Paravertebral Block Reduce the Incidence of Chronic Postsurgical Pain in Patients with Thoracoscopic Lung Cancer Surgery? A Randomized Controlled Trial

Background

Thoracoscopic lung cancer surgery is accompanied by severe pain. Both continuous paravertebral block (CPVB) and continuous wound infiltration (CWI) are widely used for perioperative analgesia in thoracoscopic surgery. However, the effects of these different methods on chronic postsurgical pain (CPSP) are still unknown. Patients and Methods. This prospective randomized controlled trial assessed the eligibility of 113 patients. Ninety-seven patients who met the inclusion criteria were randomly divided into a CPVB group and a CWI group, and 80 patients were analyzed in the final study. The primary outcome measures were the incidence and intensity of chronic postsurgical pain (CPSP) at 3, 6, and 9 months after surgery. The secondary outcome measures were the numerical rating scale (NRS) score of rest and activity at 12, 18, and 24 hours and on the 2nd, 3rd, and 7th days postoperatively; the Barthel Activities of Daily Living (ADL) score of activity levels on the 1st, 2nd, 3rd, and 7th days postoperatively; and the long-term quality of the life score at 3, 6, and 9 months postoperatively.

Results

The incidence of chronic postsurgical pain in the CWI group was significantly higher than that in the CPVB group at 3, 6, and 9 months after surgery (all P < 0.05). The intensity of chronic postsurgical pain was significantly decreased in the CPVB group at 3, 6, and 9 months after surgery (P < 0.05). NRS-R and NRS-A scores were significantly decreased in the CPVB group within the first week after thoracoscopic surgery (P < 0.001). ADL scores were increased in the CPVB group within 3 days postoperatively. However, there were no differences in the ADL score on the 7th postoperative day or the long-term quality of the life score at 3, 6, and 9 months postoperatively.

Conclusion

Continuous ultrasound-guided paravertebral block reduced the intensity of acute pain within 7 days postoperatively and reduced the incidence of chronic pain at 3, 6, and 9 months after surgery, but there was no significant advantage in long-term quality of life. This trial is registered with ChiCTR2000038505.

Efficacy of Wound Instillation With Bupivacaine Through a Wound Catheter for Postoperative Analgesia in Laparotomy Wounds in Comparison With Conventional Intravenous Analgesics

Introduction A laparotomy can cause severe postoperative pain, which, if treated adequately, can result in reduced incidence of lung atelectasis and ileus promoting early mobilization and faster recovery and in turn reducing the duration of hospital stays. Hence, effective postoperative analgesia is important to reduce postoperative stress and improve early surgical outcomes. Therefore, the hypothesis is based on the fact that following a midline laparotomy, instillation of local anaesthetic agent 0.25% bupivacaine through a wound catheter placed in the subcutaneous plane may provide better analgesia compared to the conventional intravenous analgesics and improve the early surgical outcomes. Methodology A prospective, comparative, quasi-experimental study was conducted on 80 patients planned for emergency or elective midline laparotomy procedures over a period of 18 months, who were randomly distributed into two groups of 40 each. The bupivacaine group consisted of 40 patients who received 10ml of 0.25% bupivacaine instilled through a wound catheter placed in the subcutaneous plane following a midline laparotomy. This was repeated every six hours for the first 24 hours followed by every 12 hours for the next 24 hours. The conventional intravenous (IV) analgesics group involved 40 patients who received conventional IV analgesics routinely used. Pain scores were recorded every four hours for 60 hours using the visual analogue scale (VAS) and dynamic visual analogue scale (DVAS). The parameters assessed were mean VAS and DVAS scores, number of rescue analgesic demands, cumulative rescue analgesic requirement, and early surgical outcomes. Wound complications were also assessed. Results Both groups shared similar demographic characteristics in terms of age, gender, comorbidities, and duration of operation. In comparison to patients who got standard IV analgesics, those who received 0.25% bupivacaine had improved postoperative analgesia. Between the two groups, there were statistically significant results in the number of rescue analgesic demands in the first 24 hours, but in the next 24 hours, it was statistically insignificant. The study also showed that bupivacaine instillation led to a significant decrease in postoperative lung complications and the length of hospital stays; however as hypothesised, it did not improve early surgical outcomes. Conclusion This modality, the instillation of bupivacaine through a wound catheter, is an efficient and technically simple method to provide optimal postoperative analgesia. It substantially reduces the need for systemic analgesics and can potentially avoid their related side effects. Hence, the armamentarium of multimodal analgesia can therefore include this method of delivering postoperative analgesia.

Extended Release of Bupivacaine from Temperature-responsive Hydrogels Provides Multi-day Analgesia for Postoperative Pain

OBJECTIVE

A local anesthetic that provides analgesia lasting at least three days could significantly improve postoperative pain management. This study evaluated the analgesic efficacy and safety of an extended-release formulation of bupivacaine based on the injectable hydrogel carrier poly(N-isopropylacrylamide-co-dimethylbutyrolactone acrylamide-co-Jeffamine M-1000 acrylamide) (PNDJ).

METHODS

The efficacy of PNDJ containing 4% bupivacaine (SBG004) given by peri-incisional subcutaneous injection (SBG004 SC) or wound filling instillation (SBG004 WF) was evaluated compared to saline, liposomal bupivacaine, bupivacaine collagen sponge, bupivacaine-meloxicam polyorthoester, and bupivacaine HCl in a porcine skin and muscle incision model. Mechanical allodynia was assessed by withdrawal from application of von Frey filaments, and local tolerance was evaluated by histology. Bupivacaine pharmacokinetics for SBG004 SC were measured in rabbits (16.5 mg bupivacaine/kg).

RESULTS

Animals demonstrated less mechanical allodynia at incisions receiving SBG004 SC for up to 96 hours postoperatively. Incisions treated with SBG004 SC tolerated more force without a withdrawal indicative of pain compared to saline for 96 hours, and compared to SBG004 WF and all active controls at 24, 48, and 72 hours except bupivacaine-meloxicam polyorthoester at 72 hours. By 49 days, SBG004 was histologically absent and was replaced with granulation tissue infiltrated with immune cells in some areas. In rabbits, Cmax was 41.6 ± 9.7 ng/mL with t1/2 82.0 ± 35.8 hours (mean ± SD).

CONCLUSIONS

Peri-incisional SBG004 SC provided extended release of bupivacaine sufficient to reduce sensation of incisional pain for 96 hours, in vivo bupivacaine delivery for at least 7 days, and a favorable local and systemic toxicity profile.

Management of routine postoperative pain for children undergoing cardiac surgery: a Paediatric Acute Care Cardiology Collaborative Clinical Practice Guideline

BACKGROUND

Pain following surgery for cardiac disease is ubiquitous, and optimal management is important. Despite this, there is large practice variation. To address this, the Paediatric Acute Care Cardiology Collaborative undertook the effort to create this clinical practice guideline.

METHODS

A panel of experts consisting of paediatric cardiologists, advanced practice practitioners, pharmacists, a paediatric cardiothoracic surgeon, and a paediatric cardiac anaesthesiologist was convened. The literature was searched for relevant articles and Collaborative sites submitted centre-specific protocols for postoperative pain management. Using the modified Delphi technique, recommendations were generated and put through iterative Delphi rounds to achieve consensus.

RESULTS

60 recommendations achieved consensus and are included in this guideline. They address guideline use, pain assessment, general considerations, preoperative considerations, intraoperative considerations, regional anaesthesia, opioids, opioid-sparing, non-opioid medications, non-pharmaceutical pain management, and discharge considerations.

CONCLUSIONS

Postoperative pain among children following cardiac surgery is currently an area of significant practice variability despite a large body of literature and the presence of centre-specific protocols. Central to the recommendations included in this guideline is the concept that ideal pain management begins with preoperative counselling and continues through to patient discharge. Overall, the quality of evidence supporting recommendations is low. There is ongoing need for research in this area, particularly in paediatric populations.

Efficacy of a local anesthetic gel infusion kit for pain relief after minimally invasive colorectal surgery: an open-label, randomized clinical trial

Continuous wound infusion with local anesthesia is an effective method for reducing postoperative pain after laparoscopic colorectal surgery. However, most subcutaneous local anesthesia is delivered through continuous injection, which can be inconvenient for patients. This study compared the effectiveness of postoperative pain relief from the application of a local poloxamer 407-based ropivacaine hydrogel (Gel) to the incision site with continuous infusion-type ropivacaine administration (On-Q) in patients undergoing laparoscopic colorectal surgery. This prospective, randomized, non-inferiority study included 61 patients who underwent laparoscopic colorectal surgery with an incision length of 3-6 cm. All 61 patients were randomly assigned to the Gel group (poloxamer 407-based 0.75% ropivacaine, 22.5 mg) or the On-Q group (0.2% ropivacaine, 4 mg/hour for two days). Postoperative analgesia was induced in all patients with intravenous patient-controlled analgesia (IV-PCA). The outcome measures, which were assessed for 72 h after surgery, included the total amount of fentanyl consumed via IV-PCA (primary endpoint), and the amount of rescue analgesia (pethidine) and postoperative pain intensity assessed using a numeric rating scale (NRS) [secondary endpoints]. The Gel was administered to 31 patients and On-Q was used for 30 patients. There was no significant difference in the total usage of fentanyl between the two groups (Gel group, 1623.98 mcg; On-Q group, 1595.12 mcg; P = 0.806). There was also no significant difference in the frequency of analgesic rescue medication use (P = 0.213) or NRS scores (postoperative 6 h, P = 0.860; 24 h, P = 0.333; 48 h, P = 0.168; and 72 h, P = 0.655) between the two groups. The Gel, which continuously delivers a local anesthetic to operative sites, can thus be considered an effective device for analgesia and pain relief for midline incisions in laparoscopic colorectal surgery.

A prospective cohort study to evaluate continuous wound infusion with local analgesics within an enhanced recovery protocol after colorectal cancer surgery

AIM

To reduce detrimental opioid-related side effects, minimising the postoperative opioid consumption is needed, especially in older patients. Continuous wound infusion (CWI) with local analgesics appears to be an effective opioid-sparing alternative. However, the added value of CWI to an enhanced recovery protocol after colorectal cancer (CRC) surgery is unclear. The aim of this study was to evaluate the outcomes of CWI after CRC surgery within a strictly adhered to enhanced recovery protocol.

METHODS

In this multicentre prospective observational cohort study, patients who underwent CRC surgery between May 2019 and January 2021 were included. Patients were treated with CWI as adjunct to multimodal pain management within an enhanced recovery protocol. Postoperative opioid consumption, pain scores and outcomes regarding functional recovery were evaluated.

RESULTS

A cohort of 130 consecutive patients were included, of whom 36.2% were ≥75 years. Postoperative opioids were consumed by 80 (61.5%) patients on postoperative day 0, and by 28 (21.5%), 27 (20.8%), and 18 (13.8%) patients on postoperative days 1, 2, and 3, respectively. Median pain scores were <4 on all days. The median time until first passage of stool was 1.0 (IQR: 1.0-2.0) day. Postoperative delirium occurred in 0.8%. Median length of hospital stay was 3.0 days (IQR: 2.0-5.0).

CONCLUSION

In patients treated with CWI, low amounts of postoperative opioid consumption, adequate postoperative pain control, and enhanced recovery were observed. CWI seems a beneficial opioid-sparing alternative and may further improve the outcomes of an enhanced recovery protocol after CRC surgery, which seems especially valuable for older patients.

Efficacy and safety of wound infiltration modalities for postoperative pain management after cesarean section: a systematic review and network meta-analysis protocol

BACKGROUND

Postoperative pain after a cesarean section has negative consequences for the mother during the postoperative period. Over the years, various postoperative pain management strategies have been used following cesarean section. Opioid-based analgesics and landmark approaches have negative side effects, while ultrasound-based regional analgesia necessitates resources and experience, but various wound infiltration adjuvants are innovative with few side effects and are simple to use. The efficacy and safety of each adjuvant, however, are unknown and require further investigation.

OBJECTIVE

This network meta-analysis is intended to provide the most effective wound infiltration drugs for postoperative management after cesarean section.

METHOD

A comprehensive search will be conducted in PubMed/MEDLINE, Cochrane Library, Science Direct, CINHAL, and LILACS without date and language restrictions. All randomized trials comparing the effectiveness of wound infiltration drugs for postoperative pain management after cesarean section will be included. Data extraction will be conducted independently by two authors. The quality of studies will be evaluated using the Cochrane risk of bias tool, and the overall quality of the evidence will be determined by GRADEpro software.

DISCUSSION

The rate of postoperative acute and chronic pain is very high which has a huge impact on the mother, family, healthcare practitioners, and healthcare delivery. It is a basic human right to give every patient with postoperative pain treatment that is realistic in terms of resources, technique, cost, and adverse event profile.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42021268774.

Postoperative opioid prescribing, use and pain trends following general surgery procedures: a retrospective cohort study among veterans comparing non-opioid versus chronic opioid users

INTRODUCTION

Understanding postoperative opioid use patterns among different populations is key to developing opioid stewardship programs.

METHODS

We performed a retrospective cohort study on opioid prescribing, use, and pain after general surgery procedures for patients cared for by a transitional pain service at a veterans administration hospital. Discharge opioid prescription quantity, 90-day opioid prescription, and patient reported outcome pain measures were compared between chronic opioid users and non-opioid users (NOU). Additionally, 90-day total opioid use was evaluated for NOU.

RESULTS

Of 257 patients, 34 (13%) were on chronic opioid therapy, over 50% had a mental health disorder, and 29% had a history and/or presence of a substance use disorder. NOU were prescribed a median (IQR) of 10 (7, 12) tablets at discharge, while chronic opioid users were prescribed 6 (0, 12) tablets (p<0.001). 90-day opioid prescription (not including baseline opioid prescription for chronic users) was 10 (7, 15) and 6 (0, 12) tablets, respectively (p=0.001). There were no differences in changes in pain intensity or pain interference scores during recovery between groups. Median 90-day opioid use post discharge for NOU was 4 (0, 10) pills.

DISCUSSION

Non-opioid and chronic opioid users required very few opioid pills following surgery, and patients on chronic opioid therapy quickly returned to their baseline opioid use after a small opioid prescription at discharge. There was no difference in pain recovery between groups. Opioid prescribing guidelines should include patients on chronic opioid therapy and could consider recommending a more conservative prescribing approach.

Amiodarone Provides Long-Lasting Local Anesthesia and Analgesia in Open-State Mouse Nociceptors

Local anesthetics with long-lasting effects and selectivity for nociceptors have been sought over the past decades. In this study, we investigated whether amiodarone, a multiple channel blocker, provides long-lasting local anesthesia and whether adding a TRPV1 channel activator selectively prolongs sensory anesthetic effects without prolonging motor blockade. Additionally, we examined whether amiodarone provides long-lasting analgesic effects against inflammatory pain without TRPV1 channel activator co-administration. In the sciatic nerve block model, 32 adult C57BL/6J mice received either bupivacaine, amiodarone with or without capsaicin (a TRPV1 agonist), or vehicle via peri-sciatic nerve injection. Sensory and motor blockade were assessed either by pinprick and toe spread tests, respectively. In another set of 16 mice, inflammatory pain was induced in the hind paw by zymosan injection, followed by administration of either amiodarone or vehicle. Mechanical and thermal sensitivity and paw thickness were assessed using the von Frey and Hargreaves tests, respectively. The possible cardiovascular and neurological side effects of local amiodarone injection were assessed in another set of 12 mice. In the sciatic nerve block model, amiodarone produced robust anesthesia, and the co-administration of TRPV1 agonist capsaicin prolonged the duration of sensory blockade, but not that of motor blockade [complete sensory block duration: 195.0 ± 9.8 min vs. 28.8 ± 1.3 min, F (2, 21) = 317.6, p < 0.01, complete motor block duration: 27.5 ± 1.6 min vs. 21.3 ± 2.3 min, F (2, 22) = 11.1, p = 0.0695]. In the zymosan-induced inflammatory pain model, low-dose amiodarone was effective in reversing the mechanical and thermal hypersensitivity not requiring capsaicin co-administration [50% withdrawal threshold at 8 h (g): 0.85 ± 0.09 vs. 0.25 ± 0.08, p < 0.01, withdrawal latency at 4 h (s) 8.5 ± 0.5 vs. 5.7 ± 1.4, p < 0.05]. Low-dose amiodarone did not affect zymosan-induced paw inflammation. Local amiodarone did not cause cardiovascular or central nervous system side effects. Amiodarone may have the potential to be a long-acting and nociceptor-selective local anesthetic and analgesic method acting over open-state large-pore channels.

Opioid-free versus opioid-based anesthesia in pancreatic surgery

BACKGROUND

Opioid-free anesthesia (OFA) is associated with significantly reduced cumulative postoperative morphine consumption in comparison with opioid-based anesthesia (OBA). Whether OFA is feasible and may improve outcomes in pancreatic surgery remains unclear.

METHODS

Perioperative data from 77 consecutive patients who underwent pancreatic resection were included and retrospectively reviewed. Patients received either an OBA with intraoperative remifentanil (n = 42) or an OFA (n = 35). OFA included a combination of continuous infusions of dexmedetomidine, lidocaine, and esketamine. In OBA, patients also received a single bolus of intrathecal morphine. All patients received intraoperative propofol, sevoflurane, dexamethasone, diclofenac, neuromuscular blockade. Postoperative pain management was achieved by continuous wound infiltration and patient-controlled morphine. The primary outcome was postoperative pain (Numerical Rating Scale, NRS). Opioid consumption within 48 h after extubation, length of stay, adverse events within 90 days, and 30-day mortality were included as secondary outcomes. Episodes of bradycardia and hypotension requiring rescue medication were considered as safety outcomes.

RESULTS

Compared to OBA, NRS (3 [2-4] vs 0 [0-2], P < 0.001) and opioid consumption (36 [24-52] vs 10 [2-24], P = 0.005) were both less in the OFA group. Length of stay was shorter by 4 days with OFA (14 [7-46] vs 10 [6-16], P < 0.001). OFA (P = 0.03), with postoperative pancreatic fistula (P = 0.0002) and delayed gastric emptying (P < 0.0001) were identified as only independent factors for length of stay. The comprehensive complication index (CCI) was the lowest with OFA (24.9 ± 25.5 vs 14.1 ± 23.4, P = 0.03). There were no differences in demographics, operative time, blood loss, bradycardia, vasopressors administration or time to extubation among groups.

CONCLUSIONS

In this series, OFA during pancreatic resection is feasible and independently associated with a better outcome, in particular pain outcomes. The lower rate of postoperative complications may justify future randomized trials to test the hypothesis that OFA may improve outcomes and shorten length of stay.

OUP accepted manuscript

Background

Local anaesthetic infiltration is widely used to reduce pain after laparoscopic cholecystectomy (LC). This trial evaluated the effect of depth of local anaesthetic infiltration on postoperative pain reduction after LC.

Methods

Patients undergoing elective LC between March 2018 and February 2019 were randomized into no infiltration, subcutaneous infiltration, and rectus sheath infiltration using bupivacaine. The primary outcome was 24-h postoperative cumulative morphine use, and the secondary outcomes were mean 24-h Numerical Rating Scale (NRS) for pain, and nausea, and vomiting. Subgroups were compared and multivariable analyses were performed.

Results

Out of 170 eligible patients, 162 were selected and 150 patients were analysed: 48 in the no-infiltration group, 50 in the subcutaneous infiltration group, and 52 in the rectus sheath infiltration group. The groups had similar clinical features, although mean BMI was higher in the subcutaneous infiltration group (P = 0.001). The 24-h cumulative morphine use in the rectus sheath infiltration group was significantly lower than in the no-infiltration group (P = 0.043), but no difference was observed between the subcutaneous infiltration and no-infiltration groups (P = 0.999). One hour after surgery, the rectus sheath infiltration group had a significantly lower NRS score than the no-infiltration and subcutaneous infiltration groups respectively (P = 0.006 and P = 0.031); however, the score did not differ among the three groups at any of the time points from 2 h after the surgery. The incidence of nausea or vomiting was comparable among the three groups. Multivariable analysis documented that a lower dose of morphine use was associated with rectus sheath infiltration (P = 0.004) and diabetes (P = 0.001); whereas, increased morphine use was associate with age (P = 0.040) and a longer duration of surgery (P = 0.007).

Conclusions

Local anaesthetic infiltration into the rectus sheath reduced postoperative cumulative morphine use and the immediate NRS score in patients undergoing LC; however, the pain scores were comparable 2 h after surgery.

Registration number

TCTR20201103002 (http://www.thaiclinicaltrials.org).

The Analgesic Benefits of Ketorolac to Local Anesthetic Wound Infiltration Is Statistically Significant But Clinically Unimportant: A Comprehensive Systematic Review and Meta-Analysis

Objective: Even though ketorolac-infiltration is said to provide superior postoperative analgesic benefits in different surgical procedures, its safety and efficacy remain to be validated because of the lack of high-quality evidence. We aimed to summarize the efficacy and safety of ketorolac-infiltration based on published randomized-controlled trials (RCTs). Approach: This work followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, assessing the methodological quality of systematic reviews and the Cochrane Collaboration recommendations. We searched for RCTs evaluating the efficacy of ketorolac-infiltration in adults in the PubMed, Web of Science, Embase, Cochrane Library, Chinese databases, and Google Scholar. The two co-primary outcomes of this meta-analysis were rescue analgesic consumption in the 24-h postoperative period and rest pain scores. Results: Twelve trials (761 patients) were analyzed. Ketorolac-infiltration provided a clinically unimportant benefit in morphine consumption (mean difference, -2.81 mg; 95% confidence interval [CI], -5.11 to -0.50; p = 0.02; moderate-quality evidence). Low-to-moderate quality evidence supported a brief (2-6 h), clinically subtle, but statistically consistent effect of surgical site ketorolac-infiltration in reducing wound pain at rest. High-quality evidence supported shorter hospital stays for surgical patients receiving local ketorolac-infiltration when compared to controls (mean difference, -0.12 days; 95% CI, -0.17 to -0.08; p < 0.00001). Further, ketorolac-infiltration does not improve any opioid-related side effects. Innovation: Ketorolac-infiltration provides statistically significant but clinically unimportant benefits for improving postoperative wound pain. Conclusion: Overall, despite the fact that current moderate-to-high quality of evidence does not support routine using of ketorolac as an adjuvant to local anesthetic for wound infiltration, these findings underscore the importance of optimizing agents and sustained delivery parameters in postoperative local anesthetic practice. Clinical Trials.gov ID: CRD42021229095.

Updates on Wound Infiltration Use for Postoperative Pain Management: A Narrative Review

Local anesthetic wound infiltration (WI) provides anesthesia for minor surgical procedures and improves postoperative analgesia as part of multimodal analgesia after general or regional anesthesia. Although pre-incisional block is preferable, in practice WI is usually done at the end of surgery. WI performed as a continuous modality reduces analgesics, prolongs the duration of analgesia, and enhances the patient’s mobilization in some cases. WI benefits are documented in open abdominal surgeries (Caesarean section, colorectal surgery, abdominal hysterectomy, herniorrhaphy), laparoscopic cholecystectomy, oncological breast surgeries, laminectomy, hallux valgus surgery, and radical prostatectomy. Surgical site infiltration requires knowledge of anatomy and the pain origin for a procedure, systematic extensive infiltration of local anesthetic in various tissue planes under direct visualization before wound closure or subcutaneously along the incision. Because the incidence of local anesthetic systemic toxicity is 11% after subcutaneous WI, appropriate local anesthetic dosing is crucial. The risk of wound infection is related to the infection incidence after each particular surgery. For WI to fully meet patient and physician expectations, mastery of the technique, patient education, appropriate local anesthetic dosing and management of the surgical wound with “aseptic, non-touch” technique are needed.

Postoperative pain: a review of emerging therapeutic options

INTRODUCTION

Postoperative pain is often managed by opioid medications, even though they carry a risk of adverse effects such as vomiting, constipation, sedation, respiratory depression and physical dependence. Furthermore, opioid use in the healthcare setting has likely contributed to the epidemic. However, the mismanagement of postoperative pain can result in delayed recovery time, impaired physical function, increased risk of morbidity and mortality, chronic pain, and higher healthcare costs.

AREAS COVERED

This review explores emerging therapeutic options and strategies in the management of acute postoperative pain and focuses on opioid-sparing, multimodal analgesia. This includes regional anesthetic techniques, non opioid pharmacotherapy, novel opioids and non-pharmacologic therapy. We have also discussed examples of novel analgesics and formulations which have potential benefits in reducing postoperative pain and opioid use after surgery.

EXPERT OPINION

The development of novel regional anesthesia techniques allows for opioid minimization in increasing number of surgical procedures. This synergizes with the availability of novel non-opioid analgesic adjucts. In addition, several novel opioid drugs have been developed which may be pathway selective and associated with less adverse effect than conventional opioids.

Efficacy and safety of dexmedetomidine as an adjuvant to local wound infiltration anaesthesia: A meta-analysis with trial sequential analysis of 23 randomised controlled trials

To further identify the real efficacy and safety of dexmedetomidine as an adjuvant to local wound infiltration anaesthesia, we conducted this meta‐analysis. The systematic search strategy was performed using PubMed, Embase, Cochrane Library, and Chinese databases. As a result, a total of 23 RCTs (1445 patients) were included. Patients receiving dexmedetomidine combined with local anaesthetics had a lower rescue analgesia rate [risk ratio (RR): 0.48; 95% confidence interval (CI): 0.36‐0.65] and lower rescue analgesic consumption [weighted mean difference (WMD): −10.80 mg; 95%CI: −13.28 to −8.31 mg] than patients receiving local anaesthetics alone. The dexmedetomidine‐related adverse reactions included bradycardia (RR: 1.33; 95%CI: 0.32‐5.56) and hypotension (RR: 3.00; 95%CI: 0.49‐18.42). In addition, the time to first analgesic request (WMD: 296.16 minutes; 95%CI: 165.69 minutes ~ 426.63 minutes), incidence of postoperative nausea and vomiting (PONV) and pain scores at 4 hours postoperatively were also significantly lower in patients receiving dexmedetomidine combined with local anaesthetics. This meta‐analysis demonstrated that the use of dexmedetomidine as an adjuvant to wound infiltration is effective for reducing the rescue analgesia rate, rescue analgesic consumption and PONV. In addition, limited evidence shows that dexmedetomidine can prolong postoperative analgesia for approximately 5 hours. Further investigations on dexmedetomidine‐related adverse reactions and the dose–response effect of dexmedetomidine in wound infiltration are warranted.