Clinically relevant doses of lidocaine and bupivacaine do not impair cutaneous wound healing in mice

Antinociceptive and wound healing effects of a commercial formulation of lidocaine, bupivacaine, adrenaline and cetrimide applied topically to superficial skin wounds in horses

BACKGROUND

Post-traumatic distal limb wounds cause discomfort and heal gradually by second intention. The topical application of Tri-Solfen (lidocaine hydrochloride, bupivacaine hydrochloride, adrenaline acid tartrate and cetrimide [LBAC]) produces effective postsurgical cutaneous analgesia in lambs, calves and piglets; however, its effect on wounds in horses is unknown.

METHODS

The antinociceptive effect, measured by mechanical threshold (MT), and the wound healing impacts of LBAC compared with saline were investigated on surgically created 20 × 20 mm distal limb wounds in 10 horses. Treatment was applied once daily for 7 days following wounding on day 0. Mechanical thresholds were measured after treatment on days 1, 2 and 3. Healing was observed for 25 days.

RESULTS

The topical application of LBAC immediately following wounding and its reapplication 24 hours later increased the average MT on the first post-traumatic day by 3 Newtons. However, no antinociceptive benefit was observed on days 2 or 3. Treatment with LBAC did not adversely affect wound healing when compared with saline.

LIMITATIONS

Methodological differences preclude absolute MT comparisons between studies. The experimental design did not include a model of contaminated or naturally occurring wounds.

CONCLUSION

LBAC may provide an early antinociceptive benefit when applied to uncontaminated surgically created wounds without compromising healing.

Effect of pre-incisional and peritoneal local anesthetics administration on colon anastomosis and wound healing

BACKGROUND

Previous research has shown that levobupivacaine is as effective as bupivacaine but carries a lower risk of cardiac and central nervous system toxicity. This study explores whether levobupivacaine and bupivacaine are preferable for all patients, includ-ing those with comorbidities, particularly focusing on their effects on colonic anastomosis. The primary objective is to examine the influence of levobupivacaine and bupivacaine on colonic anastomosis. Additionally, the study will assess their impact on wound healing and their anti-adhesive properties.

METHODS

Conducted between July 28, 2022, to August 4, 2022, at the Hamidiye Animal Experiments Laboratory, this study was approved by the University Science Health, Hamidiye Animal Experiments Local Ethics Committee. This study was conducted using 21 male Sprague rats aged 16-20 weeks. The rats were allocated into three equal groups of seven each: Group C: pre-incisional isotonic; Group B: pre-incisional bupivacaine; and Group L: pre-incisional levobupivacaine. Macroscopic adhesion scores (MAS) were recorded during laparotomy and tissue samples were taken for histopathological examination and hydroxyproline levels measurement. Wound tensile strength along the middle incision line and anastomotic burst pressure were also assessed.

RESULTS

MAS was statistically significantly lower in Groups B and L compared to Group C (p<0.001). The wound histopathology score (WHS) was significantly higher in Group L than in Group B (p=0.021). Colon histopathology scores (CHSs) were also signifi-cantly higher in Group L compared to Group C (p=0.011).

CONCLUSION

TThe study found that bupivacaine and levobupivacaine did not significantly enhance wound healing, although le-vobupivacaine significantly improved WHS relative to bupivacaine. According to the findings of this study, levobupivacaine can enhance clinical practice by being used in patients undergoing colon anastomosis. It contributes significantly to the durability of colon anasto-mosis, has a more positive effect on wound healing compared to bupivacaine, and exhibits anti-adhesive properties. Additional clinical trials are necessary to validate these results further.

Evaluation of primary wound healing and potential complications after perioperative infiltration with lidocaine without adrenaline in surgical incisions in dogs and cats

BACKGROUND

Pre-emptive local analgesia with the use of lidocaine is practised increasingly in veterinary medicine as part of applied multimodal analgesia, despite its controversial impact on wound healing. The purpose of this prospective, randomised, double-blinded, placebo-controlled clinical study was to evaluate if preoperative subcutaneous infiltration of lidocaine has a negative impact on primary wound healing of surgical incisions. Fifty-two companion animals (3 cats and 49 dogs) were enrolled in the study. The inclusion criteria were as follows: American Society of Anaesthesiologists (ASA) score I or II, a minimum body weight of 5 kg, and a planned incisional length of at least 4 cm. Surgical incisions were infiltrated subcutaneously with lidocaine without adrenaline or NaCl (placebo). Follow-up questionnaires for owners and veterinarians and thermography of the surgical wound were used to assess wound healing. Antimicrobial use was documented.

RESULTS

There was no significant difference in either the total score or the individual assessment points between the treatment and the placebo group on the owner or the veterinary questionnaires in regard to primary wound healing (P > 0.05 for all comparisons). No significant difference was found between the thermography results of the treatment and placebo group (P = 0.78), and there was no significant correlation between the total score from the veterinary protocol and thermography results (Spearman's correlation coefficient - 0.10, P = 0.51). Surgical site infections developed in 5/53 (9.4%) surgeries and its occurrence varied significantly between the treatment and the placebo group as all cases of infection were in the placebo group (P = 0.05).

CONCLUSION

The results of this study indicate that lidocaine used as a local anaesthetic did not affect wound healing in patients with ASA scores I-II. The results suggest that lidocaine infiltration in surgical incisions can be safely used to reduce pain.

Systematic literature review of topical local anaesthesia or analgesia to donor site wounds

BACKGROUND

Topical local analgesic and anaesthetic agents have been used both pre- and immediately post-harvest on split-thickness skin graft (STSG) donor site wounds (DSW). There is no systematic review of their effectiveness in providing post-harvest analgesia, or of the possible toxic effects of systemic absorption. This study is designed to address the question of which agent, if any, is favoured over the others and whether there are any safety data regarding their use.

METHODS

Systematic literature review of randomised controlled trials of topical agents applied to STSG DSWs, with a view to providing analgesia. Studies identified via search of Cochrane and EBSCO databases. No restrictions on language or publication year. Primary outcomes: pain at the time of (awake) STSG, and post-harvest pain (up to first dressing change). Secondary outcome was serum medication levels relative to published data on toxic doses. Cochrane risk of bias assessment tool utilised in assessment of included studies. At least 2 reviewers screened and reviewed included studies. A narrative review is presented.

RESULTS

There were 11 studies meeting inclusion criteria. Overall methodological quality and patient numbers were low. Topical eutectic mixture of lidocaine and prilocaine pre-harvest affords good local anaesthesia in awake STSG harvesting. Topical bupivacaine (5 studies) or lidocaine (1 study) gave significantly better post-harvest anaesthesia/analgesia than placebo. Topical morphine performs no better than placebo. Topical local anaesthetic agents at reported doses were all well below toxic serum levels.

CONCLUSIONS

Topical local anaesthetics (lidocaine or bupivacaine) provide good analgesia, both during and after STSG harvest, at well below toxic serum levels, but there are no good data determining the best local anaesthetic agent to use. There is no evidence morphine performs better than placebo.

Development of Nanogel Loaded with Lidocaine for Wound-Healing: Illustration of Improved Drug Deposition and Skin Safety Analysis

A wound refers to a cut or blow that may result in primary or secondary infection or even death, if untreated. In the current study, we have explored the wound-healing properties of lidocaine nanogel, owing to its antioxidant and neutrophilic modulatory potential. Initially, the pre-formulation study was performed and then using central composite design (CCD) fabrication and the characterization of lidocaine-loaded nanoemulsion was carried out. After the preparation of a nanogel of lidocaine-loaded nanoemulsion, it was evaluated on various parameters, such as pH, spreadability, extrudability, drug content, in vitro drug release, dermatokinetic study and in vivo skin safety. Based on the pre-formulation study, the maximum solubility of lidocaine was found in oleic acid (324.41 ± 4.19 mg/mL) and in Tween 20 (192.05 ± 8.25 mg/mL), selected as a suitable emulsifier. The refractive index of the optimized nanoemulsion was found to be 1.35 ± 0.04, the electrokinetic potential was recorded as −15.47 ± 0.95 mV. The pH, spreadability and extrudability of nanogel was found to be 6.87 ± 0.51, 73.32 ± 4.59 gm.cm/sec and 107.41 ± 6.42 gm/cm2, respectively. The percentage of the cumulative drug content and drug release from nanogel was found to be 99.94 ± 1.70% and 93.00 ± 4.67%, respectively. Moreover, dermatokinetic study showed significantly (p < 0.0005) improved drug deposition and the in vivo skin safety study showed no sign of dermal erythematous lesion or any visible damage. Stability studies also testified the secureness of nanogel after storage in a prescribed environmental condition. Thus, this study provides substantial evidence for healing wounds effectively and the further evaluation of the in vivo model. The patent related to this work was published in the Indian Official Journal of the Patent Office (Issue number: 20/2022).

Comparison of in vitro and in vivo Toxicity of Bupivacaine in Musculoskeletal Applications

The recent societal debate on opioid use in treating postoperative pain has sparked the development of long-acting, opioid-free analgesic alternatives, often using the amino-amide local anesthetic bupivacaine as active pharmaceutical ingredient. A potential application is musculoskeletal surgeries, as these interventions rank amongst the most painful overall. Current literature showed that bupivacaine induced dose-dependent myo-, chondro-, and neurotoxicity, as well as delayed osteogenesis and disturbed wound healing in vitro. These observations did not translate to animal and clinical research, where toxic phenomena were seldom reported. An exception was bupivacaine-induced chondrotoxicity, which can mainly occur during continuous joint infusion. To decrease opioid consumption and provide sustained pain relief following musculoskeletal surgery, new strategies incorporating high concentrations of bupivacaine in drug delivery carriers are currently being developed. Local toxicity of these high concentrations is an area of further research. This review appraises relevant in vitro, animal and clinical studies on musculoskeletal local toxicity of bupivacaine.

Closure of defects in a geometric figure pattern associated with tumescent anesthesia with lidocaine in rabbits (Oryctolagus cuniculus)

Abstract The use of tumescent anesthesia with lidocaine can provide better intra- and postoperative analgesia that would benefit extensive reconstructive surgery. However, lidocaine can interfere with the healing process. Therefore, this study aimed to assess the local interference of the healing of induced and closed skin defects in a geometric pattern associated with the use of tumescent anesthesia with lidocaine in rabbits. Furthermore, we assessed its influence on cardiorespiratory parameters and postoperative analgesia. This study included 27 rabbits divided into three groups: GC (without the use of tumescence), GS (use of tumescence with 0.9% NaCl solution), and GL (use of tumescent anesthesia with lidocaine). There was no statistically significant intergroup difference in any stage of the wound healing process on macroscopic evaluations, in the angiogenesis process, or in the process of collagenization and fibroblast deposition. There were significant differences in heart rate (lower in GL), respiratory rate (higher in GC), mean arterial pressure (higher in GL), and expired concentration of isoflurane (lower in GL). There was no significant intergroup difference in the von Frey filament test or the visual analog scale score used to evaluate postoperative analgesia. We concluded that tumescent anesthesia with lidocaine does not impair postoperative tissue repair. Its use features benefits such as reducing the volume of inhaled anesthetic, maintaining the anesthesia plan, stable heart and respiratory rates, and lower hypotension during the surgical procedure.

Perioperative Intravenous Lidocaine and Metastatic Cancer Recurrence - A Narrative Review

Cancer is a major global health problem and the second leading cause of death worldwide. When detected early, surgery provides a potentially curative intervention for many solid organ tumours. Unfortunately, cancer frequently recurs postoperatively. Evidence from laboratory and retrospective clinical studies suggests that the choice of anaesthetic and analgesic agents used perioperatively may influence the activity of residual cancer cells and thus affect subsequent recurrence risk. The amide local anaesthetic lidocaine has a well-established role in perioperative therapeutics, whether used systemically as an analgesic agent or in the provision of regional anaesthesia. Under laboratory conditions, lidocaine has been shown to inhibit cancer cell behaviour and exerts beneficial effects on components of the inflammatory and immune responses which are known to affect cancer biology. These findings raise the possibility that lidocaine administered perioperatively as a safe and inexpensive intravenous infusion may provide significant benefits in terms of long term cancer outcomes. However, despite the volume of promising laboratory data, robust prospective clinical evidence supporting beneficial anti-cancer effects of perioperative lidocaine treatment is lacking, although trials are planned to address this. This review provides a state of the art summary of the current knowledge base and recent advances regarding perioperative lidocaine therapy, its biological effects and influence on postoperative cancer outcomes.

Outcomes following single, caudally based bilateral versus unilateral frontonasal sinusotomy for treatment of equine paranasal sinus disease

Background

Bilateral sinus disease is relatively uncommon in horses, accounting for 3%–4.5% of horses with sinonasal disease, but may require bilateral paranasal surgery for complete resolution. Complications and recurrence following bilateral sinusotomy have not been reported or compared to those following unilateral procedures.

Objective

To describe clinical features and outcomes in horses undergoing standing single, caudally based bilateral frontonasal sinusotomy compared to unilateral frontonasal surgery.

Methods

Records of horses (n = 37) undergoing surgical treatment for sinus disease (five bilateral, 32 unilateral) were retrospectively reviewed (2010–2017) for signalment, presenting complaint, duration of signs preoperatively, diagnostic imaging, treatments administered, duration hospitalization, complications, and owner satisfaction with the procedure. Mann–Whitney testing was used to compare age, duration of hospitalization, and follow‐up time in horses undergoing unilateral or bilateral procedures. Fisher's exact testing was used to determine if sex predilection was present for unilateral or bilateral disease. Survival time and time to recurrence were compared by Kaplan–Meier survival curves and log‐rank curve comparison testing. Significance was assessed at p < 0.05.

Results

Length of signs prior to admission did not differ between horses with unilateral and bilateral disease (p = 0.09), but there was a tendency for horses with bilateral disease to have clinical signs for longer. Age (p = 0.19) and hospitalization duration (p = 0.53) did not differ between horses undergoing unilateral versus bilateral procedures. Recurrence or failure to resolve signs was reported in 11/32 (34%) of unilateral and 0/5 bilateral cases (p = 0.07).

Conclusions

The bilateral single, caudally based sinusotomy approach may be considered to effectively treat bilateral paranasal sinus disease without concern for increased risk of life‐threatening complications or longer hospitalization duration than would be typical for unilateral sinusotomy procedures.

Subcutaneous Bupivacaine Infiltration Is Not Effective to Support Control of Postoperative Pain in Paediatric Patients Undergoing Spinal Surgery

Spinal deformity corrections in paediatric patients are long-lasting procedures involving damage to many tissues and long pain exposure; therefore, effective pain management after surgical treatment is an important issue. In this study, the effect of inclusion of local infiltration analgesia, as an integral part of the scheme in postoperative pain control, in children and adolescents, subjected to the spinal deformity correction procedure, was assessed. Thirty patients, aged 8 to 17 years, undergoing spinal deformity correction were divided into a study group, receiving a 0.25% bupivacaine solution before wound closure, and a control group (no local analgesic agent). Morphine, at the doses of 0.10 mg/kg of body weight, was administered to the patients when pain occurred. Pain scores, morphine administration, and bleeding were observed during 48 postoperative hours. The pain scores were slightly lower in a 0–4 h period in patients who received bupivacaine compared with those in the control group. However, no differences were observed in a longer period of time and in the total opioid consumption. Moreover, increasing bleeding was observed in the bupivacaine-treated patients (study group) vs. the control. Bupivacaine only modestly affects analgesia and, due to the increased bleeding observed, it should not to be part of pain control management in young patients after spinal deformity correction.

Lidocaine and bupivacaine as part of multimodal pain management in a C57BL/6J laparotomy mouse model

While the use of local anesthesia as part of multimodal pain management is common practice in human and veterinarian surgery, these drugs are not applied routinely in rodent surgery. Several recommendations on the use of local anesthesia exist, but systematic studies on their efficacy and side effects are lacking. In the present study, male and female C57BL/6J mice were subjected to a sham vasectomy or a sham embryo transfer, respectively. We tested whether a mixture of subcutaneously injected Lidocaine and Bupivacaine in combination with systemic Paracetamol applied via drinking water results in superior pain relief when compared to treatment with local anesthesia or Paracetamol alone. We applied a combination of methods to assess behavioral, emotional, and physiological changes indicative of pain. Voluntary Paracetamol intake via drinking water reached the target dosage of 200 mg/kg in most animals. Local anesthesia did not lead to obvious side effects such as irregular wound healing or systemic disorders. No relevant sex differences were detected in our study. Sevoflurane anesthesia and surgery affected physiological and behavioral measurements. Surprisingly, Paracetamol treatment alone significantly increased the Mouse Grimace Scale. Taken together, mice treated with a combination of local anesthesia and systemic analgesia did not show fewer signs of post-surgical pain or improved recovery compared to animals treated with either local anesthesia or Paracetamol.

In vitro evaluation of loaded chitosan membranes for pain relief and infection prevention

Wounds resulting from surgeries, implantation of medical devices, and musculoskeletal trauma result in pain and can also result in infection of damaged tissue. Up to 80% of these infections are due to biofilm formation either on the surface of implanted devices or on surrounding wounded tissue. Bacteria within a biofilm have intrinsic growth and development characteristics that allow them to withstand up to 1,000 times the minimum inhibitory concentration of antibiotics, demonstrating the need for new therapeutics to prevent and treat these infections. Cis-2-decenoic acid (C2DA) is known to disperse preformed biofilms and can prevent biofilm formation entirely for some strains of bacteria. Additionally, local anesthetics like bupivacaine have been shown to have antimicrobial effects against multiple bacterial strains. This study sought to evaluate hexanoic acid-treated electrospun chitosan membranes (HA-ESCM) as wound dressings that release C2DA and bupivacaine to simultaneously prevent infection and alleviate pain associated with musculoskeletal trauma. Release profiles of both therapeutics were evaluated, and membranes were tested in vitro against Methicillin-resistant Staphylococcus aureus (MRSA) to determine efficacy in preventing biofilm infection and bacterial growth. Results indicate that membranes release both therapeutics for 72 hr, and release profile can be tailored by loading concentration. Membranes were effective in preventing biofilm growth but were toxic to fibroblasts when loaded with 2.5 or 5 mg of bupivacaine.

Topical application of lidocaine or bupivacaine in the healing of surgical wounds in dogs

Purpose:

To analyze the anesthetic drugs interference with wound healing when used in the surgical bed.

Methods:

Macro and microscopic aspects of healing of surgical wounds were evaluated after instillation of topical anesthetics without vasoconstrictor or saline solution 0.9% as control in the transsurgical period. Thirty dogs, males and females were divided into two experimental groups. In both groups, two circular punch lesions of 6 mm diameter were performed in the abdomen. In group 1, lidocaine was instilled in one of the lesions and saline solution in the contralateral lesion. In group 2 the procedure was repeated with the use of bupivacaine. The macroscopic assessment of the lesions was performed on the first, third and tenth postoperative day. The excisional biopsy was performed on the tenth day and the samples were submitted for histopathological examination.

Results:

The macroscopic analysis had a significant difference between groups. Microscopic analysis was not significant between groups.

Conclusions:

The topical application of lidocaine and bupivacaine in the surgical wound is feasible and it does not influence skin healing. The benefit of such a practice, which has been the subject of other studies, seems to outweigh the risks.

Depletion of langerin+ cells enhances cutaneous wound healing

Langerin is a C-type lectin receptor that is expressed on Langerhans cells and langerin-positive dermal dendritic cells in the skin. Little is known about the function of langerin⁺ cells in wound healing. In this study, the effects of ablation of langerin⁺ cells on healing of a full-thickness excision wound were investigated using the langerin-DTR depletable mouse. Strikingly, depletion of langerin⁺ cells resulted in more rapid reduction in wound area. Accelerated wound healing in the langerin⁺ -cell-depleted group was characterized by enhanced neo-epidermis and granulation tissue formation, and increased cellular proliferation within the newly formed tissues. Accelerated healing in the absence of langerin⁺ cells was associated with increased levels of granulocyte-macrophage colony-stimulating factor, F4/80⁺ cells and blood vessels within the granulation tissue. These data support an inhibitory role for langerin⁺ cells during wound healing. Therapies that suppress langerin⁺ cells or their function may therefore have utility in progressing the healing of wounds in humans.

Local and regional anaesthesia in dogs and cats: Descriptions of specific local and regional techniques (Part 2)

Pain management in veterinary patients is a crucial component of appropriate patient care. Local anaesthetic drugs used in local and regional blockade can completely block the transmission of nociceptive impulses, decreasing both intra‐operative nociception and postoperative pain, while decreasing the potential incidence of adverse effects that can be associated with systemic boluses of drugs. For efficacy and safety, this class of drugs is recommended as part of the analgesic protocol in the majority of surgical procedures and traumatic injuries. Numerous local and regional blocks are proven effective in dogs and cats, thus providing the clinician with ample opportunity to include these blocks in practice. This manuscript, Part 2 of a two‐part instalment, focuses on brief descriptions of select commonly used local/regional anaesthesia techniques for dogs and cats that cover a multitude of painful surgeries/injuries and that can be implemented in any practice. In Part 1 of this topic, detailed information on local anaesthetic drugs commonly used in small animal practice was reviewed (Grubb & Lobprise, 2020).

Influence of Pain and Analgesia on Orthopedic and Wound-healing Models in Rats and Mice

The surgical stress response and resulting physiologic changes can lead to postoperative complications and negatively impact animal welfare. Although appropriate pain management is crucial to reduce the pain and stress response to surgery, analgesic choice can significantly affect bone and wound healing. This review aims to summarize data from rat and mouse studies and to provide recommendations for integrating analgesia into orthopedic and wound healing models in these species. Data from other species, such as humans, rabbits and other rodents, is included, where available. From these data, we conclude that for orthopedic surgical models, opioids, local anesthetics and dissociative agents have minimal impact on fracture healing; cyclooxygenase 2 (COX2) selective nonsteroidal antiinflammatory drugs (NSAID) may be used in the shortterm; and steroids should be avoided. For wound healing models, short-term systemic or topical opioids have negligible impact on wound healing; NSAID or local anesthetics may be used short-term; and systemic steroids should be avoided. Alternative analgesics such as tramadol, gabapentin, ketamine, and acetaminophen warrant consideration and further evaluation for both orthopedic and wound healing models. In all cases, researchers and veterinarians should work together to determine the appropriate analgesic plan to minimize pain, as well as to minimize unwanted effects on the orthopedic and wound healing models themselves.

Bacterial inhibition efficiency of prilocaine and bupivacaine

This study aimed to demonstrate the antibacterial effects of bupivacaine and prilocaine on Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. In our study, the in vitro antimicrobial effects of 20 mg/mL prilocaine and 5 mg/mL bupivacaine were tested against a S. aureus American-type culture collection (ATCC) 29213, P. aeruginosa ATCC 27853, and E. coli ATCC 25922, divided into Group P (Prilocaine) and Group B (Bupivacaine), respectively. S. aureus ATCC 29213, P. aeruginosa ATCC 27853, and E. coli ATCC 25922 were cultured on Mueller Hinton agar (Oxoid, Basingstoke, UK) plates for 18 to 24 hours at 37°C. In terms of inhibition zone diameters, inhibition of S. aureus ATCC 29213 was observed in both groups at the 12th and 24th hours. The 12th- and 24th-hour S. aureus ATCC 29213 value was significantly higher in Group P compared with Group B (P = .008). At the 12th and 24th hours, inhibition of E. coli ATCC 25922 was observed in both groups. The 12th- and 24th-hour E. coli ATCC 25922 value was significantly higher in Group P compared with Group B (P = .008). In our study, it was seen that prilocaine and bupivacaine had an antimicrobial effect on S. aureus and E. coli. In the comparison between these two local anesthetics (LAs), this effect was found to be significantly higher in prilocaine than bupivacaine. Therefore, we are of the opinion that antimicrobial effect potentials should also be taken into account in the selection of an LA agent in order to prevent the complications of an infection that might develop during LA infiltration and might lead to serious morbidity.

Antimicrobial effects of local anaesthetics

After the introduction of cocaine to the medical practice, local anaesthetics (LA) became essential in pain control. LA infiltration along the incision may be used to provide surgical anaesthesia or postoperative analgesia. This study aimed to compare the antimicrobial effects of the topical antimicrobial agent mupirocine with those of the LA lidocaine and the combination of lidocaine and adrenalin. In our study, the in vitro antimicrobial effects of 1 mL sterile saline, 20 mg/mL mupirocine, 20 mg/mL Lidocaine, and 20 mg/mL Lidocaine and Adrenaline were tested against Staphylococcus aureus American type culture collection (ATCC) 29213, Pseudomonas aeruginosa ATCC 27853, and Escherichia coli ATCC 25922 as Group C (Control), Group M (Mupirocine), Group L (Lidocaine), and Group LA (Lidocaine + adrenaline), respectively. S aureus ATCC 29213, P aeruginosa ATCC 27853, and E coli ATCC 25922 were cultured onto Mueller-Hinton agar (Oxoid, UK) plates for 18 to 24 hours at 37°C. Colonies from these plates were suspended in sterile saline and a 0.5 McFarland turbidity standard suspension (corresponding to 1.5 × 10⁸  CFU/mL) of each isolate was prepared. S Aureus ATCC 29213 inhibition zone diameter values of Group M, Group LA, and Group L were significantly higher compared with the group C (P ˂ 0.05). P aeruginosa ATCC 27853 inhibition zone diameter values of Group M and Group LA were significantly higher compared with the group C (P ˂ 0.05). E coli ATCC 25922 inhibition zone diameter values of Group M, Group LA, and Group L were significantly higher compared to the group C (P ˂ 0.05). LA infiltration along the incision may be used to provide surgical anaesthesia or postoperative analgesia. Considering that LAs show antimicrobial effects besides their analgesic effects, they may contribute to preventing the development and reducing the rate of surgical infections, decreasing the requirement to administer antibiotics. However, caution should be exercised not to antagonise the effective treatment of surgical infections, remembering that controversy on the antimicrobial effects of LAs remains in the literature. Therefore, further comprehensive studies with larger patient populations are warranted to demonstrate the antimicrobial effects of LAs.

Peritonsillar infiltration of lidocaine with adrenaline is associated with increased risk of secondary post-tonsillectomy haemorrhage

OBJECTIVES

In order to evaluate the safety of tonsillectomy among children, we retrospectively studied the incidence of post-operative complications, adverse events and their association with peri-operative medication.

METHODS

Data were collected from the medical records of 691 patients aged 1-16 years, including details of post-operative complications (any unplanned contact with the hospital), analgesics, dexamethasone, 5-HT3 antagonists, local anaesthetic and haemostatic agents.

RESULTS

Recovery was complicated in 13.6 per cent of patients, of whom 8.4 per cent were re-admitted to the ward. The most common complication was post-tonsillectomy haemorrhage, experienced by 7.1 per cent of patients. Re-operation under general anaesthesia (for grade III post-tonsillectomy haemorrhage) was required by 4.2 per cent of patients. Peritonsillar infiltration of lidocaine with adrenaline increased the risk of post-tonsillectomy haemorrhage (odds ratio = 4.1; 95 per cent confidence interval = 2.1 to 8.3).

CONCLUSION

Every seventh paediatric patient experienced a complicated recovery after tonsillectomy, caused by post-tonsillectomy haemorrhage in most cases. Local peritonsillar infiltration of lidocaine with adrenaline was associated with an increased risk of post-tonsillectomy haemorrhage.

Evaluation of intraoperative analgesia provided by incisional lidocaine and bupivacaine in cats undergoing ovariohysterectomy

Objectives The objective of this study was to assess the intraoperative analgesic effect of preoperative infiltration of the incision site with lidocaine or a mixture of lidocaine with bupivacaine in cats undergoing ovariohysterectomy (OHE). Methods This was a prospective, randomised clinical study. Healthy female intact cats (n = 75) undergoing OHE under medetomidine-ketamine-buprenorphine anaesthesia were assigned randomly into three treatment groups (n = 25 per group) to receive one of two local anaesthesia protocols or placebo preoperatively in the midline incision: lidocaine 1.5 mg/kg (group GL) or mixture of lidocaine 1 mg/kg and bupivacaine 1 mg/kg (group GLB) or sodium chloride 0.9% (control group). Blood pressure, heart and respiratory rate, temperature, muscle tonus and pupillary reflex were registered during surgery. During recovery, the cats were observed for side effects. Postoperative analgesia was provided with meloxicam (0.2 mg/kg). Most cats were rechecked 2 weeks postoperatively to remove skin sutures. Results There was no significant difference between groups regarding breed, age, body weight, surgical time and postoperative complication rate. The majority of the cats (60%) included in the control group received a supplemental bolus of propofol during surgery, when compared with 43% and 44% of the cats included in the GL and GLB groups, respectively. Heart rate was significantly higher ( P <0.05) in the control group at the time of excision of the second ovary and the uterine body. Mean arterial pressure (MAP) was stable in both treatment groups; in contrast, it tended to increase in the control group. Heart rate and MAP were similar between treatment groups. Conclusions and relevance Preoperative incisional block with only lidocaine or combined with bupivacaine seems to produce a similar intraoperative analgesia in cats undergoing OHE. Despite the similar intraoperative analgesic effect between treatment groups, the combination of lidocaine and bupivacaine reduced the required doses, and had a faster onset of action and prolonged effect.

[Effects of local anesthetics on wound healing]

INTRODUCTION

Local anesthetic infiltration is used widely for post-operative analgesia in many situations. However the effects of local anesthetics on wound healing are not demonstrated clearly. This study planned to evaluate the effects of lidocaine, prilocaine, bupivacaine and levobupivacaine on wound healing, primarily on wound tensile strength and on collagen ultrastructure.

METHODS

This study was conducted on male Sprague Dawley rats. On days 0, 8th, 15th, and 21st, all animals were weighed and received a preincisional subcutaneous infiltration of 3mL of a solution according the group. Control saline (C), lidocaine (L) 7mg.kg^-1, prilocaine (P) 2mg.kg^-1, bupivacaine (B) 2mg.kg^-1 and levobupivacaine (LVB) 2.5mg.kg^-1. The infiltrations were done at the back region 1.5cm where incision would be performed at the upper, middle and lower part along the midline, under general anesthesia. Wound tensile strengths were measured after 0.7cm×2cm of cutaneous and subcutaneous tissue samples were obtained vertical to incision from infiltrated regions. Tissue samples were also obtained for electron microscopic examination. Evaluations were on the 8th, 15th and 21st days after infiltration.

RESULTS

There was no difference between groups in the weights of the rats at the 0th, 8th, 15th and 21st days. The collagen maturation was no statistically different between groups at the 8th and 15th days. The maturation scores of the B and L groups at the 21st day was significantly lower than the Group C (1.40, 1.64 and 3.56; respectively). The wound tensile strength was no statistically different between groups at the 8th and 15th days but at the 21st day the Groups B and LVB had significantly lower value than Group C (5.42, 5.54 and 6.75; respectively).

CONCLUSION

Lidocaine and prilocaine do not affect wound healing and, bupivacaine and levobupivacaine affect negatively especially at the late period.

Pain alleviation in patients undergoing cardiac surgery; presternal local anesthetic and magnesium infiltration versus conventional intravenous analgesia: a randomized double-blind study

Background

Magnesium is one of the effective, safe local anesthetic adjuvants that can exert an analgesic effect in conditions presenting acute and chronic post-sternotomy pain. We studied the efficacy of continuous infusion of presternal magnesium sulfate with bupivacaine for pain relief following cardiac surgery.

Methods

Ninety adult patients undergoing valve replacement cardiac surgery randomly allocated into three groups. In all patients; a presternal catheter was placed for continuous infusion of either 0.125% bupivacaine and 5% magnesium sulfate (3 ml/h for 48 hours) in group 1, or 0.125% bupivacaine only in the same rate in group 2, versus conventional intravenous paracetamol and ketorolac in group 3. Rescue analgesia was iv 25 µg fentanyl. Postoperative Visual Analog Scale (VAS) and fentanyl consumption during the early two postoperative days were assessed. All patients were followed up over two months for occurrence of chronic post-sternotomy pain.

Results

VAS values showed high significant differences during the first 48 hours with the least pain scale in group 1 and significantly least fentanyl consumption (30.8 ± 7 µg in group 1 vs. 69 ± 18 µg in group 2, and 162 ± 3 in group 3 respectively). The incidence of chronic pain has not differed between the three groups although it was more pronounced in group 3.

Conclusions

Continuous presternal bupivacaine and magnesium infusion resulted in better postoperative analgesia than both presternal bupivacaine alone or conventional analgesic groups.

To Treat or Not to Treat: The Effects of Pain on Experimental Parameters

A common dilemma faced by all animal bioethics committees arises when exceptions are proposed to the use of analgesics in painful procedures. The committee and researcher must weigh the possible confounding effects of including additional drugs (analgesics) in their treatment regimen against the moral obligation to perform humane research. Often neglected in these considerations are the potential confounding effects of unrelieved pain and consistency with pain-relieving practices in human medicine. In this review, we summarize what is currently known regarding the molecular and physiologic effects of pain and analgesics in common animal models used across several therapeutic areas. This work is intended to help provide guidance and assurance that a comprehensive approach has been taken when contemplating how pain relief will be applied in animal research protocols.

Pre-existing weakness is critical for the occurrence of postoperative cognitive dysfunction in mice of the same age

Occurrence of postoperative cognitive dysfunction (POCD) is age-dependent and heterogenous. Factors deciding the occurrence of POCD in patients of the same age undergone same surgeries remain unclear. Here we investigated the effects of pre-existing weakness on the occurrence of POCD in mice of the same age. Pre-existing weakness of mice was induced by intraperitoneal injection of lipopolysaccharide (8mg/kg) and was evaluated by physical frailty index (by open field test), neuroinflammation level (by Iba1 immunostaining and inflammatory factors TNF-α and IL-1β), and neuronal activity (by p-CREB immunostaining). POCD was induced by partial hepatolobectomy and was evaluated by puzzle box test and Morris water maze test. The brains were collected to detect the levels of neuroinflammation, synaptophysin and NMDA receptor subunits NR2A, NR2B and NR1 (by western blot), and oxidative stress (by Dihydroethidium). Compared to the normal adult mice of the same age, LPS pretreated mice had increased physical frailty index, higher levels of neuroinflammation, and lower neuronal activity. Partial hepatolobectomy induced obvious impairments in executive function, learning and memory in LPS pretreated mice after surgery, but not in normal mice of the same age. Partial hepatolobectomy also induced heightened neuroinflammation, obvious loss of NMDA receptor subunits, strong oxidative stress in LPS pretreated mice on the 1^st and 3^rd postoperative day. However, the POCD-associated pathological changes didn’t occur in normal mice of the same age after surgery. These results suggest that pre-existing weakness is critical for the occurrence of POCD in mice of the same age.

Lidocaine Impairs Proliferative and Biosynthetic Functions of Aged Human Dermal Fibroblasts

BACKGROUND

The aged are at increased risk of postoperative wound healing complications. Because local anesthetics are infiltrated commonly into the dermis of surgical wounds, we sought to determine whether local anesthetics adversely affect proliferative and biosynthetic functions of dermal fibroblasts. We also evaluated the effect of local anesthetics on insulin-like growth factor-1 (IGF-1) and transforming growth factor-β1 (TGF-β1), growth factors that are important regulators of wound healing.

METHODS

Human dermal fibroblasts (HFB) from aged and young donors were exposed to local anesthetic agents at clinically relevant concentrations. We screened the effects of lidocaine, bupivacaine, mepivacaine, and ropivacaine on proliferation of HFB. Lidocaine was most detrimental to proliferation in HFB. We then evaluated the effect of lidocaine on expression and function of the growth factors, IGF-1 and TGF-β1. Lastly, concurrent exposure to lidocaine and IGF-1 or TGF-β1 was evaluated for their effects on proliferation and expression of dermal collagens, respectively.

RESULTS

Lidocaine and mepivacaine inhibited proliferation in aged HFB (for lidocaine 88% of control, 95% confidence interval [CI], 80%-98%, P = .009 and for mepivacaine 90% of control, 95% CI, 81%-99%, P = .032) but not in young HFB. Ropivacaine and bupivacaine did not inhibit proliferation. Because of the clinical utility of lidocaine relative to mepivacaine, we focused on lidocaine. Lidocaine decreased proliferation in aged HFB, which was abrogated by IGF-1. Lidocaine inhibited transcripts for IGF-1 and insulin-like growth factor-1 receptor (IGF1R) in fibroblasts from aged donors (IGF-1, log2 fold-change -1.25 [42% of control, 95% CI, 19%-92%, P = .035] and IGF1R, log2 fold-change -1.00 [50% of control, 95% CI, 31%-81%, P = .014]). In contrast, lidocaine did not affect the expression of IGF-1 or IGF1R transcripts in the young HFB. Transcripts for collagen III were decreased after lidocaine exposure in aged and young HFB (log2 fold-change -1.28 [41% of control, 95% CI, 20%-83%, P = .022] in aged HFB and log2 fold-change -1.60 [33% of control, 95% CI, 15%-73%, P = .019] in young HFB). Transcripts for collagen I were decreased in aged HFB (log2 fold-change -1.82 [28% of control, 95% CI, 14%-58%, P = .006]) but not in the young HFB. Similar to the transcripts, lidocaine also inhibited the protein expression of collagen III in young and aged HFB (log2 fold-change -1.79 [29% of control, 95% CI, 18%-47%, P = .003] in young HFB and log2 fold-change -1.76 [30% of control, 95% CI, 9%-93%, P = .043] in aged HFB). The effect of lidocaine on the expression of collagen III protein was obviated by TGF-β1 in both young and aged HFB.

CONCLUSIONS

Our results show that lidocaine inhibits processes relevant to dermal repair in aged HFB. The detrimental responses to lidocaine are due, in part, to interactions with IGF-1 and TGF-β1.

Use of vacuum-assisted closure to maintain viability of a skin flap in a dog

CASE DESCRIPTION

A 4-year-old sexually intact male Labrador Retriever-Poodle mix was admitted to the hospital for treatment of a wound in the left thoracic region. The wound had been debrided and primary closure had been performed by the referring veterinarian 4 days previously.

CLINICAL FINDINGS

The dog had a 20-cm-long wound covered by a large flap of skin that extended caudally from the scapula over the left side of the thorax. A 3-cm defect was evident at the cranioventral aspect of the wound, from which purulent material was being discharged. The skin flap was necrotic, and the skin surrounding the flap was bruised. Signs of pain were elicited when the wound and surrounding region were palpated. Other findings, including those of thoracic radiography, were unremarkable.

TREATMENT AND OUTCOME

The wound was debrided, and vacuum-assisted closure (VAC) was initiated for 3 days until a healthy bed of granulation tissue developed. A reconstructive procedure was performed with a rotation flap 3 days after VAC dressing removal. The VAC process was reinitiated 2 days following reconstruction because of an apparent failing of the skin flap viability. After 5 days of VAC, the flap had markedly improved in color and consistency and VAC was discontinued. Successful healing of the flap occurred without the need for debridement or additional intervention.

CLINICAL RELEVANCE

Use of VAC led to a good overall outcome for the dog, with complete healing achieved. Additional evaluation of this technique for salvaging failing skin flaps is warranted in dogs, particularly considering that no reliable method for flap salvage in veterinary species has been reported to date.

Preperitoneal Continuous Infusion of Local Anesthetics: What Is the Impact on Surgical Wound Infections in Humans?

OBJECTIVE

Continuous surgical wound infusion with local anesthetics is an effective and widely used technique in postoperative pain management. Some aspects of this technique, however, require further investigation. The aim of this study was to retrospectively assess whether continuous infusion of ropivacaine delays the process of wound healing, with an increased incidence of infection.

DESIGN

In total, 244 patients aged between 18 and 75 years, American society of anesthesiology II-III, underwent hepatobiliary pancreatic surgery, were classified into two groups and retrospectively analyzed: group R (Ropivacaine) included 152 patients whose surgical incision was fitted with a preperitoneal catheter continuously infusing ropivacaine. Group C (Control) included 92 patients receiving a total intravenous postoperative analgesia. The evaluation forms of the surgical wound according to the Southampton wound assessment scale (SWAS) were collected at three time points. The main outcome was the rate of patients with surgical site infection within 30 days postoperatively.

RESULTS

Twenty-one patients (13.8%) in group R and 9 patients (9.8%) in group C (P = 0.35) presented wound infection. The rate of patients with a wound evaluation of a SWAS grade IV or V in three time frames in Group R and Group C was T0, 1 (0.7%) and 1 (1.08%) (P = 0.72); T1, 25 (16.4%) and 7 (7.6%) (P = 0.04); T2, 8 (5.3%) and 5 (5.4%) (P = 0.53), respectively.onclusions. The incidence of infection in the surgical site according to the centers for disease control definition was comparable in both groups. The description of the wound healing process according to the SWAS scale shows an initial and temporary decrease in maturation in group R which does not persist in the long-term.

Beneficial effects of levobupivacaine regional anaesthesia on postoperative opioid induced hyperalgesia in diabetic mice

Background

Diabetic neuropathy is one of the most common complications of diabetes and causes various problems in daily life. The aim of this study was to assess the effect of regional anaesthesia on post surgery opioid induced hyperalgesia in diabetic and non-diabetic mice.

Methods

Diabetic and non-diabetic mice underwent plantar surgery. Levobupivacaine and sufentanil were used before surgery, for sciatic nerve block (regional anaesthesia) and analgesia, respectively. Diabetic and non-diabetic groups were each randomly assigned to three subgroups: control, no sufentanil and no levobupivacaine; sufentanil and no levobupivacaine; sufentanil and levobupivacaine. Three tests were used to assess pain behaviour: mechanical nociception; thermal nociception and guarding behaviours using a pain scale.

Results

Sufentanil, alone or in combination with levobupivacaine, produced antinociceptive effects shortly after administration. Subsequently, sufentanil induced hyperalgesia in diabetic and non-diabetic mice. Opioid-induced hyperalgesia was enhanced in diabetic mice. Levobupivacaine associated to sufentanil completely prevented hyperalgesia in both groups of mice.

Conclusion

The results suggest that regional anaesthesia can decrease opioid-induced hyperalgesia in diabetic as well as in non-diabetic mice. These observations may be clinically relevant for the management of diabetic patients.

2015 AAHA/AAFP pain management guidelines for dogs and cats

RATIONALE

The robust advances in pain management for companion animals underlie the decision of the American Animal Hospital Association (AAHA) and American Association of Feline Practitioners (AAFP) to expand on the information provided in the 2007 AAHA/AAFP Pain Management Guidelines. The 2015 Guidelines summarize and offer a discriminating review of much of this new knowledge.

RELEVANCE

Pain management is central to veterinary practice, alleviating pain, improving patient outcomes, and enhancing both quality of life and the veterinarian-client-patient relationship. These Guidelines support veterinarians in incorporating pain management into practice, improving patient care.

APPROACHES

The management of pain requires a continuum of care that includes anticipation, early intervention, and evaluation of response on an individual patient basis. A team-oriented approach, including the owner, is essential for maximizing the recognition, prevention and treatment of pain in animals.

EVIDENCE BASE

The Guidelines include both pharmacologic and non-pharmacologic modalities to manage pain; they are evidence-based insofar as possible and otherwise represent a consensus of expert opinion. Behavioral changes are currently the principal indicator of pain and its course of improvement or progression, and the basis for recently validated pain scores. Post-surgical pain is eminently predictable but a strong body of evidence exists supporting strategies to mitigate adaptive as well as maladaptive forms. Chronic pain is dominated by degenerative joint disease (DJD), which is one of the most significant and under-diagnosed diseases of cats and dogs. DJD is ubiquitous, found in pets of all ages, and inevitably progresses over time; evidence-based strategies for management are established in dogs, and emerging in cats.

Effects of analgesic use on inflammation and hematology in a murine model of venous thrombosis

Venous thrombosis (VT) is a significant cause of morbidity and mortality in humans. Surgical animal models are crucial in studies investigating the pathogenesis of this disease and evaluating VT therapies. Because inflammation is critical to both the development and resolution of VT, analgesic medications have the potential to adversely affect multiple parameters of interest in VT research. The objective of this study was to determine how several common analgesics affect key variables in a murine ligation model of deep vein thrombosis. Male C57BL/6 mice were randomly assigned to receive either local (bupivacaine) or systemic parenteral analgesia (buprenorphine, tramadol, or carprofen) or 0.9% NaCl (control). All mice underwent laparotomy and ligation of the inferior vena cava, and treatment was continued until euthanasia at 6 or 48 h after surgery. Analysis of harvested tissues and blood included: hematology, thrombus weight, serum and vein-wall cytokines (IL1β, IL6, IL10, TNFα), soluble P-selectin, and vein-wall leukocyte infiltration. Compared with 0.9% NaCl, all of the analgesics affected multiple parameters important to VT research. Carprofen and tramadol affected the most parameters and should not be used in murine models of VT. Although they affected fewer parameters, a single dose of bupivacaine increased thrombus weight at 6 h, and buprenorphine was associated with reduced vein wall macrophages at 48 h. Although we cannot recommend the use of any of the evaluated analgesic dosages in this mouse model of VT, buprenorphine merits additional investigation to ensure the highest level of laboratory animal care and welfare.

Ketamine is toxic to chondrocyte cell cultures

Ketamine has been used in combination with a variety of other agents for intra-articular analgesia, with promising results. However, although it has been shown to be toxic to various types of cell, there is no available information on the effects of ketamine on chondrocytes.

We conducted a prospective randomised controlled study to evaluate the effects of ketamine on cultured chondrocytes isolated from rat articular cartilage. The cultured cells were treated with 0.125 mM, 0.250 mM, 0.5 mM, 1 mM and 2 mM of ketamine respectively for 6 h, 24 hours and 48 hours, and compared with controls. Changes of apoptosis were evaluated using fluorescence microscopy with a 490 nm excitation wavelength. Apoptosis and eventual necrosis were seen at each concentration. The percentage viability of the cells was inversely proportional to both the duration and dose of treatment (p = 0.002 and p = 0.009). Doses of 0.5 mM, 1 mM and 2mM were absolutely toxic.

We concluded that in the absence of solid data to support the efficacy of intra-articular ketamine for the control of pain, and the toxic effects of ketamine on cultured chondrocytes shown by this study, intra-articular ketamine, either alone or in combination with other agents, should not be used to control pain.

Cite this article: Bone Joint J 2014; 96-B:989–94.

Comparison of the effects of bupivacaine, lidocaine, and tramadol infiltration on wound healing in rats

BACKGROUND AND OBJECTIVES

The aim of this study was to investigate the effects of saline solution, bupivacaine, lidocaine and tramadol infiltration on wound healing in rats.

METHOD

Thirty-two male Wistar Albino rats were randomly separated into four groups, receiving 3 mL saline solution in control group (Group C, n=8), 3 mL of 2% lidocaine in lidocaine group (Group L, n=8), 3 mL of 0.5% bupivacaine in bupivacaine group (Group B, n=8), and 3 mL of 5% tramadol in tramadol group (Group T, n=8). Breaking-strength measurements, collagen bundle counting, and histopathologic evaluation were evaluated in the tissue samples taken from the rats.

RESULTS

Comparing the control group with the groups where bupivacaine and lidocaine were used for wound infiltration, collagen production was lower, breaking-strength measurements showed reduced resistance while significantly high edema, vascularity, inflammation scores were found (p<0.0125). Between the control and the tramadol group there were no significant differences in collagen production, breaking-strength measurements, and edema, vascularity, inflammation scores (p>0.0125).

CONCLUSION

In our study, we found bupivacaine and lidocaine reduced the collagen production, wound breaking strength, and caused significantly high scores for edema, vascularity, and inflammation when compared to the control group. There was no significant difference between the control and the tramadol group. Results of this experimental preliminary study on rats support the idea that tramadol can be used for wound infiltration anesthesia without adverse effect on the surgical healing process. These results need to be verified in humans.

Postoperative analgesic effect of intravenous (i.v.) clonidine compared with clonidine administration in wound infiltration for open cholecystectomy

OBJECTIVES

This randomized double-blind study was designed to compare the postoperative analgesic effect of clonidine administered intravenously or in wound infiltration with bupivacaine.

METHODS

Sixty adults of ASA grade I-II undergoing open cholecystectomy were randomly allocated into three groups. Group 1 (control group) patients received wound infiltration with 30 ml of 0.25% bupivacaine at the end of surgery. Group 2 patients received 3 μg kg(-1) clonidine intravenously after resection of gall bladder plus wound infiltration with 30 ml of 0.25% bupivacaine. Group 3 patients received wound infiltration with 3 μg kg(-1) clonidine with 30 ml of 0.25% bupivacaine. A standard general anaesthesia technique was used. Postoperative analgesia was provided with i.v. diclofenac and morphine on demand. Postoperative pain, number of patients requiring rescue analgesia and total morphine consumption during 24 h after operation was recorded.

RESULTS

Postoperative morphine consumption was significantly less in patients receiving clonidine by either route when compared with the control group (P<0.0001). All patients in the control group required supplemental morphine, with nine patients in the i.v. clonidine group and 11 patients in the wound infiltration group (P<0.002). Pain scores were lower at rest for 12 h and on cough for 6 h in both clonidine groups when compared with the control group (P<0.01). Patients receiving i.v. clonidine had more hypotension (P<0.01) and sedation (P<0.001) compared with other groups.

CONCLUSIONS

Clonidine 3 μg kg(-1) provided effective postoperative analgesia and reduced morphine requirement when administered intravenously or in wound infiltration with bupivacaine. However, the incidence of complications was less with wound infiltration. CLINICAL TRIAL REGISTRY OF INDIA: (www.ctri.nic.in/), registration number CTRI/2012/12/003258.

Bupivacaine and levobupivacaine induce apoptosis in rat chondrocyte cell cultures at ultra-low doses

PURPOSE

Osteoarthritis (OA) is characterized by chondrocyte apoptosis and necrosis which play a key role during the progression of OA. Intra-articular administration of bupivacaine is a practical and effective way of postoperative pain control following various joint surgeries. 0.25 % bupivacaine showed to be safe in terms of chondrocyte toxicity. Around 200 nM of bupivacaine was shown to be effective for peripheral nerve block. This study aims to observe the possible cytotoxic effects of bupivacaine and its enantiomer levobupivacaine on chondrocyte cell culture at 7.69, 76.9, and 384.5 μM or at 0.0125, 0.0025, and 0.00025 % concentrations, respectively.

METHODS

Chondrocytes were isolated from rat articular cartilage after incubating with collagenase in RPMI-1640 medium. Cells were treated with bupivacaine and levobupivacaine at 7.69, 76.9, and 384.5 μM concentrations for 6, 24, and 48 h. Treated chondrocytes were stained with acridine orange and ethidium bromide and examined under a fluorescence microscope at a 490 nm excitation wavelength for apoptotic changes.

RESULTS

Study results suggest that both bupivacaine and levobupivacaine have dose-dependent chondrocyte toxicity, and this is significantly lesser at 7.69 μM dose. There was no significant difference in terms of chondrocyte apoptosis, (p > 0.05).

CONCLUSIONS

Clinicians should be skeptic for the serious long-term side effects of bupivacaine and its analogs, even at ultra-low doses.

Effects of levobupivacaine on wound healing

BACKGROUND

Local anesthetic infiltration along the incision may be used to provide surgical anesthesia or postoperative analgesia. However, the effect of local anesthetics on wound healing remains controversial. In this investigation, we evaluated the effects of levobupivacaine on wound healing.

METHODS

Sixty Wistar albino female rats weighing 230±20 g were included, with 10 rats in each group: group early c (early control): 3 mL isotonic saline; group early l1.25 (early levobupivacaine 1.25): 1.25 mg/kg per 3 mL levobupivacaine; group early l2.5 (early levobupivacaine 2.5): 2.5 mg/kg per 3 mL levobupivacaine; group late c (late control): 3 mL isotonic saline; group late l1.25 (late levobupivacaine 1.25): 1.25 mg/kg per 3 mL levobupivacaine; and group late l2.5 (late levobupivacaine 2.5): 2.5 mg/kg per 3 mL levobupivacaine. Rats in groups early c to early l2.5 were euthanized on the 8th day. Rats in groups late c to late l2.5 were euthanized on the 21st day. Wound tension strength, tissue hydroxyproline, and fibrotic index levels of the tissue samples from the early c and early l2.5 and late c and late l2.5 groups, respectively, on the 8th and 21st days were examined.

RESULTS

Levobupivacaine decreased wound tension strength on the 8th day, especially a 2.5 mg/kg dose (P<0.001), and increased it on the 21st day (P<0.001). It also increased the inflammatory response (P<0.001) and collagen synthesis (8th day, P=0.109; 21st day, P=0.103) on both the 8th and 21st days.

CONCLUSIONS

While levobupivacaine had a positive effect on wound healing during the early period, negative effects were observed thereafter. Additional studies at the molecular level are necessary to determine the cause of these apparently opposite effects.

[Postoperative wound infections. Pathophysiology, risk factors and preventive concepts]

Postoperative wound infections are the third most common type of nosocomial infection in German emergency hospitals after pneumonia and urinary infections. They are associated with increased morbidity and mortality, prolonged hospital stay and increased costs. The most important risk factors include the microbiological state of the skin surrounding the incision, delayed or premature prophylaxis with antibiotics, duration of surgery, emergency surgery, poorly controlled diabetes mellitus, malignant disease, smoking and advanced age. Anesthesiological measures to decrease the incidence of wound infections are maintaining normothermia, strict indications for allogenic blood transfusions and timely prophylaxis with antibiotics. Blood glucose concentrations should be kept in the range of 8.3-10 mmol/l (150-180 mg/dl) as lower values are associated with increased complications. Intraoperative and postoperative hyperoxia with 80% O(2) has not been shown to effectively decrease wound infections. The application of local anesthetics into the surgical wound in clinically relevant doses for postoperative analgesia does not impair wound healing.