Re: reduction in pain associated with open carpal tunnel decompression

Wide Awake Open Carpal Tunnel Release: The Effect of Local Anesthetics in the Postoperative Outcome

Introduction  Wide awake open carpal tunnel decompression is a procedure performed under local anesthesia. This study aimed to present the effect of various local anesthetics in peri and postoperative analgesia in patients undergoing this procedure. Materials and Methods  A total of 140 patients, with 150 hands involved, underwent carpal tunnel release under local anesthesia. Patients were divided in five groups according to local anesthetic administered: lidocaine 2%, ropivacaine 0.75%, ropivacaine 0.375%, chirocaine 0.5%, and chirocaine 0.25%. Total 400 mg of gabapentin were administered to a subgroup of 10 cases from each group (50 cases totally), 12 hours before surgery. Patients were evaluated immediately, 2 weeks and 2 months after surgery according to VAS pain score, grip strength, and two-point discrimination. Results  In all patients, pain and paresthesia improved significantly postoperatively, while the use of gabapentin did not affect outcomes. Grip strength recovered and exceeded the preoperative value 2 months after surgery, without any difference between the groups. No case of infection, hematoma, or revision surgery was reported. Conclusion  Recovery after open carpal tunnel release appears to be irrelevant of the type of local anesthetic used during the procedure. Solutions of low local anesthetic concentration (lidocaine 2%, ropivacaine 0.375%, and chirocaine 0.25%) provide adequate intraoperative analgesia without affecting the postoperative course.

Sensation of Pain Using Buffered Lidocaine for Infiltration Before Vulvar Biopsy: A Randomized Controlled Trial

OBJECTIVE

To evaluate the effects of buffered lidocaine on pain scores during vulvar biopsy.

METHODS

We conducted a double-blind, randomized controlled trial, using prefilled, sequentially numbered, randomized syringes to infiltrate either 3 mL of buffered or nonbuffered lidocaine before vulvar biopsy. The primary outcome was a pain score marked on a 100-mm visual analog scale during infiltration. Secondary outcomes included pain scores after the procedure and change from baseline to infiltration. Participants were recruited to detect a clinically meaningful 15-mm difference in pain scores between groups. Sample size was calculated based on the null hypothesis that the mean pain score would be the same in women treated with buffered lidocaine as in those treated with nonbuffered placebo based on prior studies. Categorical data were compared by Fisher exact test, and continuous data were compared between groups by t-test or Wilcoxon rank sum test.

RESULTS

From July 2015 to April 2018, 129 participants were randomized to one of two groups: nonbuffered lidocaine or buffered lidocaine. One hundred twenty-five were analyzed (nonbuffered n=62, buffered n=63). Four patients were excluded. The majority of participants were non-Hispanic white women with a mean age of 59 years. There was no difference in the primary outcome of pain during infiltration with a mean pain score of 35.8 mm in the buffered lidocaine group compared with 42.2 in the nonbuffered lidocaine group (mean difference -6.4; 95% CI -18.4 to 5.6; P=.3 by Wilcoxon rank sum test). There was also no difference in secondary outcomes of pain over the entire procedure (mean difference -0.3, 95% CI -9.7 to 9.2; P=.7) or change in pain from baseline to infiltration (mean difference -6.9, 95% CI -18.4 to 4.7; P=.2).

CONCLUSION

There was no difference in pain scores during vulvar biopsy infiltration between the buffered and nonbuffered lidocaine groups.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT02698527.

Randomized Trial of Buffered Versus Plain Lidocaine for Local Anaesthesia in open Carpal Tunnel Decompression

We performed a randomized double-blind case–control study in 64 consecutive patients undergoing open carpal tunnel decompression under local anaesthetic to assess the pain experienced on injection of plain lidocaine (pH 6.4) compared with lidocaine buffered with sodium bicarbonate (pH 7.4). The results showed no statistical difference in the pain scores reported by patients. The mean pain scores for all patients were low, and most patients reported that they were “not at all anxious” about receiving a similar injection in the future.

The Use of a Fine-Gauge Needle to Reduce Pain in Open Carpal Tunnel Decompression: A Randomized Controlled Trial

This randomized controlled study on 86 patients compared the level of pain experienced by patients on instillation of local anaesthetic into the palm with a 23-gauge and a 27-gauge (dental) needle in open carpal tunnel decompression. Patients were asked to score the amount of pain they experienced during the injection of the local anaesthetic and their level of anxiety about future injections using a visual analogue scale (VAS) and a four-point verbal response scale (VRS). The mean pain and anxiety scores on the VAS were significantly lower in the dental needle group. There was significant correlation between the pain and anxiety VAS scores. When infiltrating local anaesthetic into the palm for open carpal tunnel decompression, the use of a fine (dental) needle can reduce the pain on that occasion and the anxiety concerning future injections likely to be experienced by the patient.

Pain Levels after Local Anaesthetic with or without Hyaluronidase in Carpal Tunnel Release: A Randomised Controlled Trial

Purpose. Hyaluronidase is an enzyme that temporarily liquefies the interstitial barrier, allowing easy dispersal of local anaesthetic through cleavage of tissue planes. This prospective, blinded, randomised controlled study investigates the utility of adding hyaluronidase to local anaesthetic in the setting of carpal tunnel release. Methods. 70 consecutive carpal tunnel release patients were recruited and randomised into a control group only receiving local anaesthetic and a hyaluronidase group receiving both hyaluronidase and local anaesthetic. Pain scores were rated using the visual analogue scale (VAS) by patients immediately after local anaesthetic injection and again immediately after the carpal tunnel release. Results. Preoperative VAS scores, taken after local anaesthetic injection, were greater than postoperative VAS scores. Postoperative VAS scores were significantly lower in the hyaluronidase group and tourniquet times were significantly shorter in the hyaluronidase group. Conclusion. Hyaluronidase addition to local anaesthetic in carpal tunnel release resulted in significant reductions in operative time and pain immediately after operation.

How acidic is the lidocaine we are injecting, and how much bicarbonate should we add?

BACKGROUND

The infiltration of local anesthetics can be painful, which is likely due, in part, to their acidity. In spite of a Cochrane study that recommended neutralizing lidocaine with bicarbonate to decrease the pain of injection, not many surgeons have adopted the practice, and there are many 'recipes' for how much bicarbonate one should add.

OBJECTIVE

To determine the acidity of lidocaine and the correct ratio of bicarbonate that should be added to neutralize lidocaine to achieve body pH.

METHODS

Fifty samples each of commonly used anesthetics (lidocaine 1% and 2%, with and without epinephrine 1:100,000) were obtained and tested for pH. Data were also analyzed according to whether the vials had been previously opened. Ten additional samples of lidocaine 1% with 1:100,000 epinephrine were titrated against sodium bicarbonate 8.4% and tested for pH and the presence of precipitate.

RESULTS

A solution of 1% lidocaine with 1:100,000 epinephrine had a mean (± SD) pH of 4.24±0.42, and 2% lidocaine with 1:100,000 epinephrine had a mean pH of 3.93±0.43. Plain 1% lidocaine had a pH of 6.09±0.16, and plain 2% lidocaine had a pH of 6.00±0.27. Epinephrine-containing solutions were more acidic when they had been previously opened. One per cent lidocaine with epinephrine required 8.4% sodium bicarbonate at a ratio of 1.1 mL:10 mL to 1.8 mL:10 mL to achieve the target tissue pH of 7.38 to 7.62.

CONCLUSION

Lidocaine with epinephrine was approximately 1000 times more acidic than subcutaneous tissue. The addition of bicarbonate to the local anesthetic solution is simple to perform and is inexpensive. The proper volume ratio of 8.4% sodium bicarbonate to 1% lidocaine with 1:100,000 epinephrine is approximately 1 mL:10 mL. Surgeons should be more aware of the simplicity and value of buffering with bicarbonate to decrease the pain of injection.

Remifentanil-propofol sedation as an ambulatory anesthesia for carpal tunnel release

OBJECTIVE

This prospective study evaluated the use of continuous sedation using propofol and remifentanil when carpal tunnel release (CTR) was performed under local anesthesia.

METHODS

We sedated 60 patients undergoing CTR using local anesthesia with remifentanil at loading and continuous doses of 0.5 µg kg(-1) and 0.05 µg kg(-1)min(-1), respectively, and propofol, using a target controlled infusion (TCI) pump set to a target of 2 µg mL(-1) (group A), or with the same drug doses except that the continuous remifentanil dose was 0.07 µg kg(-1)min(-1) (group B) or 0.1 µg kg(-1)min(-1) (group C).

RESULTS

In group B, the levels of pain when local anesthetics were administered (p = 0.001), intraoperative pain (p < 0.001) and anxiety (p = 0.001) were significantly lower than those of group A. Furthermore, the incidence of adverse events, including desaturation (p < 0.001) and vomiting (p = 0.043), was significantly lower in group B than in group C.

CONCLUSION

Continuous sedation using an appropriate dose of remifentanil and propofol can be used as safe, efficacious ambulatory anesthesia in cases of CTR under local anesthesia, performed using only 2 mL of local anesthetic, with a high degree of patient satisfaction.

Reducing the pain associated with local anaesthetic infiltration for open carpal tunnel decompression

This prospective, randomized study assessed the effectiveness of buffering lidocaine with sodium bicarbonate for reducing the pain associated with local anaesthetic infiltration for open carpal tunnel decompression. Twenty-one patients undergoing bilateral open carpal tunnel decompression received, in a randomized manner, lidocaine 1% with adrenaline (1:200,000) in one hand and the same local anaesthetic buffered with 8.4% NaHCO3 at a 5:1 ratio in the other hand. Pain, especially its burning element, was evaluated on a visual analogue scale and was significantly reduced with the buffered solution. The buffering was effective for all patients and no adverse effects were noted. This is a safe, easy and quick method for making open carpal tunnel surgery less uncomfortable to patients.

Carpal ligament decompression under local anaesthesia: the effect of lidocaine warming and alkalinisation on infiltration pain

This study investigated the effects of alkalinization and warming of lidocaine 1% on injection pain in patients undergoing carpal tunnel decompression. Sixty-four adult patients were randomly allocated into one of three groups: Group A (n=20) received plain lidocaine 1%, Group B (n=22) alkalinized lidocaine and Group C (n=22) warmed and alkalinized lidocaine. Pain on needle insertion and on infiltration was assessed using a 100mm Visual Analogue Scale (VAS). There was no significant difference regarding pain on needle insertion whereas significant differences were noted in reference to infiltration pain. In Groups B and C (alkalinized lidocaine) the VAS scores on skin infiltration were significantly lower than in Group A, while the pain score in Group C (alkalinized and warmed lidocaine) was significantly lower than in Group B.