The comparative preemptive analgesic efficacy of addition of vitamin B complex to gabapentin versus gabapentin alone in women undergoing cesarean section under spinal anesthesia: A prospective randomized double-blind study

Mechanisms of action of vitamin B1 (thiamine), B6 (pyridoxine), and B12 (cobalamin) in pain: a narrative review

Pain is a complex sensory and emotional experience with nociceptive, nociplastic, and neuropathic components. An involvement of neurotropic B vitamins (B1 - thiamine, B6 - pyridoxine, and B12 - cyanocobalamin) as modulators of inflammation and pain has been long discussed. New evidence suggests their therapeutic potential in different pain conditions. In this review, we discuss the main role of neurotropic B vitamins on different nociceptive pathways in the nervous system and to describe their analgesic action mechanisms. The performed literature review showed that, through different mechanisms, these vitamins regulate several inflammatory and neural mediators in nociceptive and neuropathic pain. Some of these processes include aiming the activation of the descending pain modulatory system and in specific intracellular pathways, anti-inflammatory, antioxidative and nerve regenerative effects. Moreover, recent data shows the antinociceptive, antiallodynic, and anti-hyperalgesic effects of the combination of these vitamins, as well as their synergistic effects with known analgesics. Understanding how vitamins B1, B6, and B12 affect several nociceptive mechanisms can therefore be of significance in the treatment of various pain conditions.

A Latin American consensus meeting on the essentials of mixed pain

OBJECTIVES

The term "mixed pain" has been established when a mixture of different pain components (e.g. nociceptive, neuropathic, and nociplastic) are present. It has gained more and more acceptance amongst pain experts worldwide, but many questions around the concept of mixed pain are still unsolved. The sensation of pain is very personal. Cultural, social, personal experiences, idiomatic, and taxonomic differences should be taken into account during pain assessment. Therefore, a Latin American consensus committee was formed to further elaborate the essentials of mixed pain, focusing on the specific characteristics of the Latin American population.

METHODS

The current approach was based on a systematic literature search and review carried out in Medline. Eight topics about the definition, diagnosis, and treatment of mixed pain were discussed and voted for by a Latin American consensus committee and recommendations were expressed.

RESULTS

At the end of the meeting a total of 14 voting sheets were collected. The full consensus was obtained for 21 of 25 recommendations (15 strong agreement and 6 unanimous agreement) formulated for the above described 8 topics (7 of the 8 topics had for all questions at least a strong agreement - 1 topic had no agreement for all 4 questions).

CONCLUSION

In a subject as complex as mixed pain, a consensus has been reached among Latin American specialists on points related to the definition and essence of this pain, its diagnosis and treatment. Recommendations for diagnosis and treatment of mixed pain in Latin America were raised.

Perioperative micronutrients, macroscopic benefits?

'Micronutrients' are vitamins and minerals vital for healthy metabolic function, wound healing and disease and infection prevention. Micronutrients may play a role in significantly improving postoperative recovery and indices of patient comfort; however, minimal research exists for surgical patients. Furthermore, current guidelines on perioperative nutrition have a macronutrient focus which may fail to guide detection and treatment of the subclinical micronutrient deficiency in a patient who is not obviously malnourished. Limited research into supplementation of some micronutrient deficiencies shows favourable results; however, given the financial implications of wound care, the prevalence of micronutrient deficiency and possible benefits from attention to micronutrition for postoperative recovery, further research into this area is urgently warranted. Interventions to guide optimal future clinical practice are suggested.

Effects of a BMI1008 mixture on postoperative pain in a rat model of incisional pain

Background

The purpose of this study was to evaluate the analgesic effect of BMI1008 (a new drug containing lidocaine, methylene blue, dexamethasone and vitamin B complex) and to investigate the analgesic effect of lidocaine and BMI-L (other components of BMI1008 except lidocaine) at different concentrations in a rat model of incisional pain.

Methods

Male Sprague-Dawley rats (250–300 g) were used for the incisional pain model simulating postoperative pain. After the operation, normal saline, various concentrations of BMI1008, lidocaine with a fixed concentration of BMI-L, and BMI-L with a fixed concentration of lidocaine were injected at the incision site. The preventive analgesic effect was evaluated using BMI1008 administered 30 min before and immediately after the operation. In addition, BMI1008 was compared with positive controls using intraperitoneal ketorolac 30 mg/kg and fentanyl 0.5 μg/kg. The mechanical withdrawal threshold was measured with a von Frey filament.

Results

The analgesic effect according to the concentration of BMI1008, lidocaine with a fixed concentration of BMI-L, and BMI-L with a fixed concentration of lidocaine showed a concentration-dependent response and statistically significant difference among the groups (P <0.001, P <0.001, and P <0.001, respectively). The analgesic effect according to the time point of administration (before and after the operation) showed no evidence of a statistically significant difference between the groups (P = 0.170). Compared with the positive control groups, the results showed a statistically significant difference between the groups (P = 0.024).

Conclusion

BMI1008 showed its analgesic effect in a rat model of incisional pain in a concentration-dependent manner. Moreover, BMI-L showed an additive effect on the analgesic effect of lidocaine.

Multivitamin Use in Enhanced Recovery After Surgery Protocols: A Cost Analysis

INTRODUCTION

Enhanced Recovery After Surgery (ERAS) protocols have shown significant benefits in multiple areas including early mobilization, improved pain control, and early oral intake. Deficient nutritional states may compromise the operative outcomes. Several essential vitamins, e.g., B12, C, D, and E, have demonstrated anti-inflammatory properties and may promote wound healing. Given the low risk of oral multivitamin supplementation and the potential benefits, we hypothesized that adding a multivitamin to our institution's ERAS protocols would be a low-cost perioperative intervention accounting for a very small fraction of the annual pharmacy budget.

METHODS

A cost analysis for vitamin supplementation for all adult orthopedic surgical cases for the fiscal year 2018 was conducted. To assess the potential cost for multivitamin supplementation in the perioperative period, the fiscal year 2018 pharmacy budget and current costs of multivitamins were obtained from the hospital pharmacy. Medication costs were obtained from the medical logistics ordering system at per unit (i.e., bottle) and per tablet levels for all formulary oral multivitamins. We also determined the number of adult orthopedic surgical cases for our facility in the fiscal year 2018 from our surgery scheduling system. The cost for supplementation for a single day (day of surgery), 1 week (first postoperative week), 6 weeks plus 1 week preop, and 6 months plus 1 week preop for all cases was then calculated.

RESULTS

Our institution's pharmacy budget for the fiscal year 2018 was $123 million dollars with two oral multivitamins on formulary. Prenatal tablets, containing vitamins A-E, calcium, iron, and zinc, cost $1.52 per bottle of 100 tablets and $0.0152 per tablet, while renal formulation tablets, containing water-soluble vitamins B and C, cost $2.79 per bottle of 100 tablets and $0.0279 per tablet. For one fiscal year, the medication cost to supplement every adult orthopedic surgery patient with an oral multivitamin for 1 day, 1 week, 6 weeks plus 1 week preop, and 6 months plus 1 week preop would range from $60.47 to $110.99, from $423.29 to $776.93, from $2,963.03 to $5,438.51, and from $10,582.25 to $19,423.25, respectively, depending on which multivitamin was prescribed. These costs would represent between 0.00005% and 0.00009% of the annual pharmacy budget for 1 day, between 0.0003% and 0.0006% for 1 week, between 0.00245% and 0.441% for 6 weeks plus 1 week preop, and between 0.00875% and 1.575% for 6 months plus 1 week preop, respectively.

DISCUSSION/CONCLUSIONS

The relative nutrient-deficient state in the perioperative patient from decreased oral intake contributes to the metabolic derangements resulting from the surgery. The current ERAS protocols help to mitigate this with early feeding, and the addition of multivitamin supplementation may enhance this process. Multivitamins are safe, widely accessible, and inexpensive, and early investigations of pain control and healing have shown encouraging results. Further prospective studies are needed for incorporating multivitamins into ERAS protocols in order to elucidate the effective dosages, duration of treatment, and effect on outcomes.

Non-drug pain relievers active on non-opioid pain mechanisms

This review is aimed to summarize the pain-relieving effect of non-drug substances, mostly prescribed as integrators in treatment of pain, including especially in chronic postoperative pain (CPSP) and in chronic back pain after acute episodes. Their use reflects the fact that the current treatments for these syndromes continue to pose problems of unsatisfactory responses in a significant portion of patients and/or of an excess of side effects like those noted in the present opioid crisis. As integrators are frequently introduced into the market without adequate clinical testing, this review is aimed to collect the present scientific evidence either preclinical or clinical for their effectiveness. In particular, we reviewed the data on the use of: B vitamins; vitamin C; vitamin D; alpha lipoic acid (ALA); N-acetylcysteine; acetyl L-carnitine; curcumin; boswellia serrata; magnesium; coenzyme Q10, and palmitoylethanolamide. The combination of preclinical findings and clinical observations strongly indicate that these compounds deserve more careful attention, some of them having interesting clinical potentials also in preventing chronic pain after an acute episode. In particular, examining their putative mechanisms of action it emerges that combinations of few of them may exert an extraordinary spectrum of activities on a large variety of pain-associated pathways and may be eventually used in combination with more traditional pain killers in order to extend the duration of the effect and to lower the doses. Convincing examples of effective combinations against pain are vitamin B complex plus gabapentin for CPSP, including neuropathic pain; vitamin B complex plus diclofenac against low back pain and also in association with gabapentin, and ALA for burning mouth syndrome. These as well as other examples need, however, careful controlled independent clinical studies confirming their role in therapy.

[Role of B vitamins, thiamine, pyridoxine, and cyanocobalamin in back pain and other musculoskeletal conditions: a narrative review]

Low back pain, as well as other musculoskeletal disorders (neck pain, osteoarthritis, etc.), are a very frequent cause of consultation both in primary care and in other hospital specialties and are usually associated with high functional and work disability. Acute low back pain can present different nociceptive, neuropathic and nonciplastic components, which leads to consider it as a mixed type pain. The importance of the concept of mixed pain is due to the fact that the symptomatic relief of these pathologies requires a multimodal therapeutic approach to various pharmacological targets. The antinociceptive role of the B vitamin complex has been recognized for several decades, specifically the combination of Thiamine, Pyridoxine and Cyanocobalamin (TPC). Likewise, there is accumulated evidence that indicates an adjuvant analgesic action in low back pain. The aim of the present review is to present the existing evidence and the latest findings on the therapeutic effects of the TPC combination in low back pain. Likewise, some of the most relevant mechanisms of action involved that can explain these effects are analyzed. The reviewed evidence indicates that the combined use of PCT has an adjuvant analgesic effect in mixed pain, specifically in low back pain and other musculoskeletal disorders with nociceptive and neuropathic components. This effect can be explained by an anti-inflammatory, antinociceptive, neuroprotective and neuromodulatory action of the TPC combination on the descending pain system.

PROSPECT guideline for elective caesarean section: updated systematic review and procedure-specific postoperative pain management recommendations

Caesarean section is associated with moderate‐to‐severe postoperative pain, which can influence postoperative recovery and patient satisfaction as well as breastfeeding success and mother‐child bonding. The aim of this systematic review was to update the available literature and develop recommendations for optimal pain management after elective caesarean section under neuraxial anaesthesia. A systematic review utilising procedure‐specific postoperative pain management (PROSPECT) methodology was undertaken. Randomised controlled trials published in the English language between 1 May 2014 and 22 October 2020 evaluating the effects of analgesic, anaesthetic and surgical interventions were retrieved from MEDLINE, Embase and Cochrane databases. Studies evaluating pain management for emergency or unplanned operative deliveries or caesarean section performed under general anaesthesia were excluded. A total of 145 studies met the inclusion criteria. For patients undergoing elective caesarean section performed under neuraxial anaesthesia, recommendations include intrathecal morphine 50–100 µg or diamorphine 300 µg administered pre‐operatively; paracetamol; non‐steroidal anti‐inflammatory drugs; and intravenous dexamethasone administered after delivery. If intrathecal opioid was not administered, single‐injection local anaesthetic wound infiltration; continuous wound local anaesthetic infusion; and/or fascial plane blocks such as transversus abdominis plane or quadratus lumborum blocks are recommended. The postoperative regimen should include regular paracetamol and non‐steroidal anti‐inflammatory drugs with opioids used for rescue. The surgical technique should include a Joel‐Cohen incision; non‐closure of the peritoneum; and abdominal binders. Transcutaneous electrical nerve stimulation could be used as analgesic adjunct. Some of the interventions, although effective, carry risks, and consequentially were omitted from the recommendations. Some interventions were not recommended due to insufficient, inconsistent or lack of evidence. Of note, these recommendations may not be applicable to unplanned deliveries or caesarean section performed under general anaesthesia.

Complementary and alternative therapies for post-caesarean pain

BACKGROUND

Pain after caesarean sections (CS) can affect the well-being of the mother and her ability with her newborn. Conventional pain-relieving strategies are often underused because of concerns about the adverse maternal and neonatal effects. Complementary alternative therapies (CAM) may offer an alternative for post-CS pain.

OBJECTIVES

To assess the effects of CAM for post-caesarean pain.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register, LILACS, PEDro, CAMbase, ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP) (6 September 2019), and checked the reference lists of retrieved articles.

SELECTION CRITERIA

Randomised controlled trials (RCTs), including quasi-RCTs and cluster-RCTs, comparing CAM, alone or associated with other forms of pain relief, versus other treatments or placebo or no treatment, for the treatment of post-CS pain.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed study selection, extracted data, assessed risk of bias and assessed the certainty of evidence using GRADE.

MAIN RESULTS

We included 37 studies (3076 women) which investigated eight different CAM therapies for post-CS pain relief. There is substantial heterogeneity among the trials. We downgraded the certainty of evidence due to small numbers of women participating in the trials and to risk of bias related to lack of blinding and inadequate reporting of randomisation processes. None of the trials reported pain at six weeks after discharge. Primary outcomes were pain and adverse effects, reported per intervention below. Secondary outcomes included vital signs, rescue analgesic requirement at six weeks after discharge; all of which were poorly reported, not reported, or we are uncertain as to the effect Acupuncture or acupressure We are very uncertain if acupuncture or acupressure (versus no treatment) or acupuncture or acupressure plus analgesia (versus placebo plus analgesia) has any effect on pain because the quality of evidence is very low. Acupuncture or acupressure plus analgesia (versus analgesia) may reduce pain at 12 hours (standardised mean difference (SMD) -0.28, 95% confidence interval (CI) -0.64 to 0.07; 130 women; 2 studies; low-certainty evidence) and 24 hours (SMD -0.63, 95% CI -0.99 to -0.26; 2 studies; 130 women; low-certainty evidence). It is uncertain whether acupuncture or acupressure (versus no treatment) or acupuncture or acupressure plus analgesia (versus analgesia) has any effect on the risk of adverse effects because the quality of evidence is very low. Aromatherapy Aromatherapy plus analgesia may reduce pain when compared with placebo plus analgesia at 12 hours (mean difference (MD) -2.63 visual analogue scale (VAS), 95% CI -3.48 to -1.77; 3 studies; 360 women; low-certainty evidence) and 24 hours (MD -3.38 VAS, 95% CI -3.85 to -2.91; 1 study; 200 women; low-certainty evidence). We are uncertain if aromatherapy plus analgesia has any effect on adverse effects (anxiety) compared with placebo plus analgesia. Electromagnetic therapy Electromagnetic therapy may reduce pain compared with placebo plus analgesia at 12 hours (MD -8.00, 95% CI -11.65 to -4.35; 1 study; 72 women; low-certainty evidence) and 24 hours (MD -13.00 VAS, 95% CI -17.13 to -8.87; 1 study; 72 women; low-certainty evidence). Massage We identified six studies (651 women), five of which were quasi-RCTs, comparing massage (foot and hand) plus analgesia versus analgesia. All the evidence relating to pain, adverse effects (anxiety), vital signs and rescue analgesic requirement was very low-certainty. Music Music plus analgesia may reduce pain when compared with placebo plus analgesia at one hour (SMD -0.84, 95% CI -1.23 to -0.46; participants = 115; studies = 2; I2 = 0%; low-certainty evidence), 24 hours (MD -1.79, 95% CI -2.67 to -0.91; 1 study; 38 women; low-certainty evidence), and also when compared with analgesia at one hour (MD -2.11, 95% CI -3.11 to -1.10; 1 study; 38 women; low-certainty evidence) and at 24 hours (MD -2.69, 95% CI -3.67 to -1.70; 1 study; 38 women; low-certainty evidence). It is uncertain whether music plus analgesia has any effect on adverse effects (anxiety), when compared with placebo plus analgesia because the quality of evidence is very low. Reiki We are uncertain if Reiki plus analgesia compared with analgesia alone has any effect on pain, adverse effects, vital signs or rescue analgesic requirement because the quality of evidence is very low (one study, 90 women). Relaxation Relaxation may reduce pain compared with standard care at 24 hours (MD -0.53 VAS, 95% CI -1.05 to -0.01; 1 study; 60 women; low-certainty evidence). Transcutaneous electrical nerve stimulation TENS (versus no treatment) may reduce pain at one hour (MD -2.26, 95% CI -3.35 to -1.17; 1 study; 40 women; low-certainty evidence). TENS plus analgesia (versus placebo plus analgesia) may reduce pain compared with placebo plus analgesia at one hour (SMD -1.10 VAS, 95% CI -1.37 to -0.82; 3 studies; 238 women; low-certainty evidence) and at 24 hours (MD -0.70 VAS, 95% CI -0.87 to -0.53; 108 women; 1 study; low-certainty evidence). TENS plus analgesia (versus placebo plus analgesia) may reduce heart rate (MD -7.00 bpm, 95% CI -7.63 to -6.37; 108 women; 1 study; low-certainty evidence) and respiratory rate (MD -1.10 brpm, 95% CI -1.26 to -0.94; 108 women; 1 study; low-certainty evidence). We are uncertain if TENS plus analgesia (versus analgesia) has any effect on pain at six hours or 24 hours, or vital signs because the quality of evidence is very low (two studies, 92 women).

AUTHORS' CONCLUSIONS

Some CAM therapies may help reduce post-CS pain for up to 24 hours. The evidence on adverse events is too uncertain to make any judgements on safety and we have no evidence about the longer-term effects on pain. Since pain control is the most relevant outcome for post-CS women and their clinicians, it is important that future studies of CAM for post-CS pain measure pain as a primary outcome, preferably as the proportion of participants with at least moderate (30%) or substantial (50%) pain relief. Measuring pain as a dichotomous variable would improve the certainty of evidence and it is easy to understand for non-specialists. Future trials also need to be large enough to detect effects on clinical outcomes; measure other important outcomes as listed lin this review, and use validated scales.

Perioperative analgesia after intrathecal fentanyl and morphine or morphine alone for cesarean section: A randomized controlled study

OBJECTIVES

Intrathecal morphine is used in the postoperative management of pain after caesarean section (CS), but might not be optimal for intraoperative analgesia. We hypothesized that intrathecal fentanyl could supplement intraoperative analgesia when added to a local anesthetic and morphine without affecting management of postoperative pain.

METHODS

This prospective, randomized, double-blind, parallel-group study included 60 parturients scheduled for elective CS. Spinal anesthesia consisted of bupivacaine with either morphine 100 μg (M group), or fentanyl 25 μg and morphine 100 μg (FM group). The frequency of intraoperative pain and pethidine consumption in the 24 hours postoperatively was recorded.

RESULTS

Fewer patients in the FM group required additional intraoperative analgesia (P < .01, relative risk 0.06, 95% confidence interval [CI] 0.004-1.04). The FM group was noninferior to the M group for 24-hour opioid consumption (95% CI -10.0 mg to 45.7 mg, which was below the prespecified boundary of 50 mg). Pethidine consumption in postoperative hours 1 to 12 was significantly higher in the FM group (P = .02). Postoperative nausea and vomiting (PONV) were more common in the FM group (P = .01). Visual analog scale scores, effective analgesia, Apgar scores, and rates of pruritus and respiratory depression were similar between the groups.

CONCLUSIONS

Intrathecal combination of fentanyl and morphine may provide better perioperative analgesia than morphine alone in CS and could be useful when the time from anesthesia to skin incision is short. However, an increase in PONV and possible acute spinal opioid tolerance after addition of intrathecal fentanyl warrants further investigation using lower doses of fentanyl.