Pre-emptive analgesia and surgical pain

Efficacy and safety of 4-hydroxy-2-methyl-N-(5-methyl-2-thiazolyl)-2H-1, 2-benzothiazin-3-carboxamide 1,1-dioxide, a rapid-acting meloxicam formulation, for analgesia after orthopaedic surgery under general anaesthesia: a randomized controlled trial

BACKGROUND

Postoperative pain management is one of the most challenging treatments after orthopaedic surgery, and improved medical treatment options are urgently needed. This study aimed to evaluate the efficacy and safety of 4-hydroxy-2-methyl-N-(5-methyl-2-thiazolyl)-2H-1, 2-benzothiazin-3-carboxamide 1,1-dioxide (QP001) for moderate to severe pain following orthopaedic surgery.

METHODS

This randomized clinical trial enlisted patients experiencing moderate to severe pain following orthopaedic surgery in 20 hospitals in China. We allocated randomly 132 participants to receive 30 mg QP001 and 66 participants to receive 0.9% saline pre-surgery. The primary efficacy outcome was the total morphine consumption within 24 h.

RESULTS

The total morphine consumption in the QP001 group, versus placebo group, was significantly lower over the following 24 h [12.53 (10.51) vs. 26.13 (13.98), P < 0.001]. The total morphine consumption in the QP001 group, versus placebo group, was also significantly decreased over the following 48 h (P < 0.001). The QP001 group, versus placebo, showed a significant decrease in the effective pressing times of the analgesic pump, morphine relief analgesia ratio over the 24 h and 48 h periods and the area under the curve for pain intensity-time as well as a significant prolonged in the time of first pressing the analgesic pump and the time of first morphine rescue analgesia (P < 0.001). The QP001 groups, versus placebo, show no significant difference in adverse events, but the incidence of adverse drug reactions decreased (59.4% vs. 75.8%, P = 0.023).

CONCLUSION

QP001 provides analgesia and reduces opioid consumption in patients with moderate to severe pain after orthopaedic surgery, with a favorable safety profile.

Transdermal buprenorphine patch as an adjunct to multimodal analgesia after total joint arthroplasty: a retrospective cohort study

Background

Total hip arthroplasty or total knee arthroplasty (THA/TKA) is often associated with varying degrees of pain. In recent years, transdermal buprenorphine (TDB) patch has shown encouraging results for acute postoperative pain control in orthopedic surgery. The aim of our study was to investigate the efficacy and safety of the combination of TDB patch and nonsteroidal anti-inflammatory drugs (NSAIDs) as a multimodal analgesic regimen after THA/TKA.

Methods

Patients who underwent THA and TKA between January 2022 and January 2023 were reviewed. Three postoperative analgesic regimens were selected: Group A (flurbiprofen 50 mg and tramadol 37.5 mg/acetaminophen 325 mg), Group B (flurbiprofen 50 mg and TDB 5 mg), and Group C (Parecoxib 40 mg and TDB 5 mg). The primary outcomes were the Wong-Baker face pain scale revision (FPS-R) scores and the rate of sleep disturbances. Secondary outcomes of the study included the proportion of patients with postoperative pain relief rates categorized as 0%, <50%, ≥50%, and 100%.

Results

The dynamic FPS-R pain scores on day 3 after surgery in Group B were significantly lower than those in Group A for THA (P < 0.017). The dynamic FPS-R pain scores were lowest in Group C on day 2 and 3 after THA and TKA (P < 0.017). Rate of sleep disturbances was significantly lower in Group B for THA and in Group C for TKA, respectively, compared with that in Group A (P < 0.017). The proportion of dynamic pain relief rate ≥50% in Group C was statistically higher than that in Group A for THA (P < 0.017). Rate of adverse reactions among three groups for THA and TKA was not statistically different (P > 0.05).

Conclusion

This study suggests that the combination of TDB patch and NSAIDs is safe and effective for postoperative analgesia after THA/TKA.

Does Local Infiltration of Anesthesia Reduce Port-site Pain in Gynecological Laparoscopic Surgeries? A Pilot Study

Objectives

The objectives of this study were to evaluate the visual analog scale (VAS) score in patients receiving port-site bupivacaine infiltration in gynecological laparoscopic surgeries and to compare it with those receiving placebo and to evaluate the additional analgesic requirement in the first 24 h after surgery.

Materials and Methods

A prospective interventional study was conducted on 60 women scheduled for benign gynecological laparoscopic surgeries. Patients were randomized into two groups using an alternative sequential method of allocation. Approval from the Institute's Ethics Committee was sought. Informed written consent was taken from all the patients. All laparoscopic surgeries were performed under general anesthesia. Double-blinding was done. A VAS with a 10 cm vertical score ranging from "no pain" to "worst possible pain" was used to assess the postoperative pain when the patient awakened in the operating room (2 h after surgery), then after 6 and 24 h. The primary outcome measured was pain perception by the patient (as VAS scores), and the secondary outcome was the need for additional analgesia.

Results

Comparison of both groups with the VAS score shows P > 0.001, i.e., nonsignificant in all the groups. Additional analgesics were required in 56% of the patients in the intervention group and 60% of the patients in the control group; however, 44% and 40% of the patients from the intervention and control groups, respectively, do not require any additional analgesic in the postoperative period.

Conclusion

The local infiltration of bupivacaine does not significantly reduce the port-site postoperative pain in gynecological laparoscopic surgeries.

Preemptive QP001, a fast-acting meloxicam formulation, provides analgesia and reduces opioid consumption following abdominal surgery: a randomized controlled trial

BACKGROUND

QP001, a novel meloxicam formulation, has been developed to manage moderate to severe postoperative pain. This study aimed to evaluate the efficacy and safety of QP001 injections for moderate to severe pain following abdominal surgery.

METHOD

This prospective, multicenter, randomized, double-blind, placebo-controlled clinical trial enlisted patients experiencing moderate to severe pain following abdominal surgery. These patients were randomized to receive either QP001 injections (30 mg or 60 mg) or a placebo pre-surgery. The primary efficacy endpoint was the total morphine consumption within 24 h after the first administration.

RESULTS

A total of 108 patients were enrolled, and 106 patients completed the study. The total morphine consumption in the QP001 30 mg group and 60 mg group, versus placebo group, were significantly lower over the following 24 h (5.11[5.46] vs 8.86[7.67], P = 0.011; 3.11[3.08] vs 8.86[7.67], P < 0.001), respectively. The total morphine consumption in the QP001 30 mg and 60 mg groups, versus placebo group, was also significantly decreased over the following 48 h, including the 24-48 h period (P ≤ 0.001). The QP001 30 mg and 60 mg groups, versus placebo, showed a significant decrease in the area under the curve for pain intensity-time as well as a significant decrease in the effective pressing times of the analgesic pump over the 24 h and 48 h periods (P < 0.05). The QP001 groups, versus placebo, show no significant different in Adverse Events or Adverse Drug Reactions (P > 0.05).

CONCLUSION

Preoperative/preemptive QP001 provides analgesia and reduces opioid consumption in patients with moderate to severe pain following abdominal surgery, while maintaining a favorable safety profile.

Enhanced Recovery After Surgery Pathway in Kidney Transplantation: The Road Less Traveled

Enhanced recovery after surgery (ERAS) pathway is a multimodal perioperative care pathway designed to achieve early recovery after surgery. ERAS protocols have not yet been well recognized in kidney transplantation. The aim of this study was to investigate the impact of ERAS pathway on early recovery and short-term clinical outcomes of kidney transplant.

Postoperative Acupuncture is as Effective as Preoperative Acupuncture or Meloxicam in Dogs Undergoing Ovariohysterectomy: a Blind Randomized Study

Background

Acupuncture has the same analgesic effect as non-steroidal antiinflammatory drugs and opioids. It is challenging to perform preoperative acupuncture in unmanageable animals, while the residual postoperative anesthetic effect facilitates the performance of acupuncture postoperatively.

Objectives

To compare preoperative acupuncture or meloxicam versus postoperative acupuncture for postoperative analgesia after ovariohysterectomy.

Methods

This is a horizontal prospective positive control blind randomized experimental study. Thirty-six dogs were randomly divided into three groups: GA (preemptive acupuncture), GPA (postoperative acupuncture), and GM (meloxicam 0.2 mg/kg IV preoperatively). After sedation with acepromazine (0.05 mg/kg IM), anesthesia was induced with propofol (5.3 ± 0.3 mg/kg) and maintained with isoflurane/O2. Fentanyl (2 μg/kg, IV) was administered immediately before surgery. Bilateral acupuncture was performed at acupoints Large intestine 4, Spleen 6, and Stomach 36 for 20 minutes, before (GA) or immediately after surgery (GPA). Pain was evaluated by an observer blind to the treatment using the Glasgow scale before and for 24 hours after ovariohysterectomy. Dogs with a score ≥ 6 received rescue analgesia with morphine (0.5 mg/kg IM). Nonparametric data were analyzed by the Kruskal-Wallis test, followed by Dunn's test and parametric data by ANOVA followed by Tukey's test.

Results

Two GA and one GPA dogs received rescue analgesia once. Two GM dogs received rescue analgesia and one of those was treated again twice. There were no differences in the number of dogs receiving rescue analgesia between groups (p = 0.80).

Conclusion

Postoperative acupuncture was as effective as preoperative acupuncture or meloxicam in female dogs undergoing ovariohysterectomy.

The effect of preemptive local anesthesia on postoperative pain following vaginal hysterectomy: A randomized controlled trial

OBJECTIVE

We aimed to study the effect of preemptive local anesthetic without adrenaline on postoperative pain following vaginal hysterectomy and concomitant trans obturator tape (TOT).

STUDY DESIGN

This was a double-blinded, randomized, controlled trial. Women who undergone elective vaginal hysterectomy were included. Solutions of either Bupivacaine-Hydrochloride 0.5%, or Sodium-Chloride 0.9% as a placebo, were prepared prior to surgery, according to randomization. The chosen solution was injected before incision, in a circumferential manner, to the cervix. The amount of fluid administered was 10 ml. When colporrhaphy was also performed, an additional 5 ml of solution were injected in the midline of the vaginal wall prior to each incision line. We conformed to the CONSORT recommendations. By utilizing the 10 cm Visual-analogue-scale (VAS) we assessed post-operative pain at rest at 3, 8, and 24 h, and during ambulation at 8 and 24 h. We estimated that the intervention would cause a 25% reduction in the primary outcome. The required total sample size was calculated to be 30 patients women for each group. We used ANOVA for continuous variables and the Chi-square or Fisher exact tests for categorical variables.

RESULTS

A total of 30 women were included in each group. The level of postoperative pain, as assessed by VAS, was not significantly different between the groups, in all points of time. In addition, there was no difference between the groups in opioid based analgesics during recovery, nor in postoperative analgesic use.

CONCLUSION

Preemptive local anesthesia was not shown to be efficient in reducing postoperative pain after vaginal hysterectomy and TOT.

The effect of subcutaneous and intraperitoneal anesthesia on post laparoscopic pain: a randomized controlled trial

A few modes of perioperative local analgesia have been studied in order to reduce postoperative pain after laparoscopy, including preemptive local anesthetics in the trocar sites and intraperitoneal anesthetics administration at the end of the surgery. However, the evidence regarding their efficacy are conflicting. In addition, the combination of both aforementioned methods has been rarely studied. Our aim was to evaluate whether subcutaneous trocar site and/or intraperitoneal analgesia reduce pain after gynecologic operative laparoscopy. This was a single-centered, randomized, controlled, double-blinded trial. The patients were randomly assigned to one of four equally sized groups: group 1-subcutaneous and intraperitoneal analgesia; group 2-subcutaneous analgesia and intraperitoneal placebo; group 3-subcutaneous placebo and intraperitoneal analgesia; Group 4-subcutaneous and intraperitoneal placebo. The patients, the surgeons, and the pain evaluators were all blinded to the patient's allocation. Included were patients who underwent elective operative laparoscopy. Exclusion criteria were: active infection, pregnancy, known sensitivity to Bupivacaine-Hydrochloride, chronic pelvic pain, surgeries with additional vaginal procedures, conversion to laparotomy, and malignancy. A total of 9 ml of Bupivacaine-Hydrochloride (Marcaine) 0.5%, or Sodium-Chloride 0.9%, as a placebo, were injected subcutaneously to the trocar sites (3 ml to each trocar site), prior to skin incision. In addition, 10 ml of Bupivacaine-Hydrochloride 0.5%, diluted with 40 ml of Sodium-Chloride 0.9% (a total of 50 ml solution), or 50 ml of Sodium-Chloride 0.9%, as a placebo, were injected intraperitoneally at the end of the surgery. By utilizing the 10 cm Visual-analogue-scale (VAS) we assessed post-operative pain at rest at 3, 8, and 24 h, and during ambulation at 8 and 24 h. The study was approved by the local Institutional Review Board and has been registered at clinicaltrials.gov. We conformed to the CONSORT recommendations. Between December 2016 and July 2019, a total of 119 patients were included in the study. Demographic and interventional characteristics were similar among the groups. The level of postoperative pain, either at rest or with change of position, was not significantly different between the groups, at all-time points. Application of subcutaneous and/or intraperitoneal analgesia is not effective in reducing pain after gynecologic operative laparoscopy.Clinical trial identification number: NCT02976571. Date of trial registration 11/29/2016. URL of the registration site: https://clinicaltrials.gov .

Antinociceptive and anti-inflammatory effects of ginsenoside Rf in a rat model of incisional pain

Background

Ginseng saponin has long been used as a traditional Asian medicine and is known to be effective in treating various kinds of pain. Ginsenoside Rf is one of the biologically active saponins found in ginseng. We evaluated ginsenoside Rf’s antinociceptive and anti-inflammatory effects, and its mechanism of action on adrenergic and serotonergic receptors, in an incisional pain model.

Methods

Mechanical hyperalgesia was induced via plantar incision in rats followed by intraperitoneal administration of increasing doses of ginsenoside Rf (vehicle, 0.5 mg/kg, 1 mg/kg, 1.5 mg/kg, and 2 mg/kg). The antinociceptive effect was also compared in a Positive Control Group that received a ketorolac (30 mg/kg) injection, and the Naïve Group, which did not undergo incision. To evaluate the mechanism of action, rats were treated with prazosin (1 mg/kg), yohimbine (2 mg/kg), or ketanserin (1 mg/kg) prior to receiving ginsenoside Rf (1.5 mg/kg). The mechanical withdrawal threshold was measured using von Frey filaments at various time points before and after ginsenoside Rf administration. To evaluate the anti-inflammatory effect, serum interleukin (IL)-1β, IL-6, and tumor necrotizing factor-α levels were measured.

Results

Ginsenoside Rf increased the mechanical withdrawal threshold significantly, with a curvilinear dose–response curve peaking at 1.5 mg/kg. IL-1β, IL-6, and tumor necrotizing factor-α levels significantly decreased after ginsenoside Rf treatment. Ginsenoside Rf’s antinociceptive effect was reduced by yohimbine, but potentiated by prazosin and ketanserin.

Conclusion

Intraperitoneal ginsenoside Rf has an antinociceptive effect peaking at a dose of 1.5 mg/kg. Anti-inflammatory effects were also detected.

Comparative study between effect of pre- versus post-incisional transversus abdominis plane block on acute and chronic post-abdominal hysterectomy pain

Background:

The prevalence of persistent chronic pain after abdominal hysterectomy is 5–32%. Our objectives were to determine the influence of transversus abdominis plane (TAP) block on the incidence of acute and chronic post-hysterectomy pain and to examine potential associations between time of block administration, either before surgical incision (preemptive) or after end of surgical procedure and its effect.

Materials and Methods:

Seventy-five patients undergoing elective total abdominal hysterectomy under general anesthesia were allocated randomly to receive TAP block either pre-incisional, or before emergence from anesthesia or sham block (just a needle puncture, control group). Pain was evaluated postoperatively at rest and movement by visual analogue scale. Peri-operative analgesic requirements, sedation, postoperative nausea and vomiting scores were recorded. Patients were questioned at three, and six months after surgery for type and severity of chronic pain.

Results:

Pain scores were significantly higher in Group II versus Group I (P<0.05), but both demonstrated significantly lower pain scores than control Group. Analgesic requirements decreased significantly in patients received TAP block (P<0.0001) with more significant decrease in the pre-incisional group. The incidence of chronic pain was significantly reduced in the pre-incisional group than others. The incidence of sedation was noted to be higher in the control group (61%) versus other groups (18% and 32% respectively), at time point 12 h postoperatively but was comparable between 12, 48 h (awake and alert). Incidence of postoperative nausea and vomiting (PONV) was reduced in patients who received TAP block (16% and 29%) in Group I and II respectively versus 66.5% in Group III. There were no complications attributed to the TAP block.

Results:

Pain scores were significantly higher in Group II versus Group I (P<0.05), but both demonstrated significantly lower pain scores than control Group. Analgesic requirements decreased significantly in patients received TAP block (P<0.0001) with more significant decrease in the pre-incisional group. The incidence of chronic pain was significantly reduced in the pre-incisional group than others. The incidence of sedation was noted to be higher in the control group (61%) versus other groups (18% and 32% respectively), at time point 12 h postoperatively but was comparable between 12, 48 h (awake and alert). Incidence of postoperative nausea and vomiting (PONV) was reduced in patients who received TAP block (16% and 29%) in Group I and II respectively versus 66.5% in Group III. There were no complications attributed to the TAP block.

Conclusions:

TAP block seems to be an acceptable choice for postoperative analgesia; pre-incisional TAP block appeared to reduce the severity of acute pain, analgesic requirements with its undesirable side-effects and incidence of chronic pain in comparison with blockade before emergence from anesthesia.

A comparison of effect of preemptive use of oral gabapentin and pregabalin for acute post-operative pain after surgery under spinal anesthesia

BACKGROUND AND AIMS

Preemptive analgesia is an antinociceptive treatment that prevents establishment of altered processing of afferent input. Pregabalin has been claimed to be more effective in preventing neuropathic component of acute nociceptive pain of surgery. We conducted a study to compare the effect of oral gabapentin and pregabalin with control group for post-operative analgesia.

MATERIALS AND METHODS

A total of 90 ASA grade I and II patients posted for elective gynecological surgeries were randomized into 3 groups (group A, B and C of 30 patients each). One hour before entering into the operation theatre the blinded drug selected for the study was given with a sip of water. Group A- received identical placebo capsule, Group B- received 600mg of gabapentin capsule and Group C - received 150 mg of pregabalin capsule. Spinal anesthesia was performed at L3-L4 interspace and a volume of 3.5 ml of 0.5% bupivacaine heavy injected over 30sec through a 25 G spinal needle. VAS score at first rescue analgesia, mean time of onset of analgesia, level of sensory block at 5min and 10 min interval, onset of motor block, total duration of analgesia and total requirement of rescue analgesia were observed as primary outcome. Hemodynamics and side effects were recorded as secondary outcome in all patients.

RESULTS

A significantly longer mean duration of effective analgesia in group C was observed compared with other groups (P < 0.001). The mean duration of effective analgesia in group C was 535.16 ± 32.86 min versus 151.83 ± 16.21 minutes in group A and 302.00 ± 24.26 minutes in group B. The mean numbers of doses of rescue analgesia in the first 24 hours in group A, B and C was 4.7 ± 0.65, 4.1 ±0.66 and 3.9±0.614. (P value <0.001).

CONCLUSION

We conclude that preemptive use of gabapentin 600mg and pregabalin 150 mg orally significantly reduces the postoperative rescue analgesic requirement and increases the duration of postoperative analgesia in patients undergoing elective gynecological surgeries under spinal anesthesia.

The effectiveness of preemptive thoracic epidural analgesia in thoracic surgery

BACKGROUND

The aim of this study is to investigate the effectiveness of preemptive thoracic epidural analgesia (TEA) comparing conventional postoperative epidural analgesia on thoracotomy.

MATERIAL AND METHODS

Forty-four patients were randomized in to two groups (preemptive: Group P, control: Group C). Epidural catheter was inserted in all patients preoperatively. In Group P, epidural analgesic solution was administered as a bolus before the surgical incision and was continued until the end of the surgery. Postoperative patient controlled epidural analgesia infusion pumps were prepared for all patients. Respiratory rates (RR) were recorded. Patient's analgesia was evaluated with visual analog scale at rest (VASr) and coughing (VASc). Number of patient's demands from the pump, pump's delivery, and additional analgesic requirement were also recorded.

RESULTS

RR in Group C was higher than in Group P at postoperative 1st and 2nd hours. Both VASr and VASc scores in Group P were lower than in Group C at postoperative 1st, 2nd, and 4th hours. Patient's demand and pump's delivery count for bolus dose in Group P were lower than in Group C in all measurement times. Total analgesic requirements on postoperative 1st and 24th hours in Group P were lower than in Group C.

CONCLUSION

We consider that preemptive TEA may offer better analgesia after thoracotomy.

Antihyperalgesic effects of ginseng total saponins in a rat model of incisional pain

BACKGROUND

The aim of this study was to assess whether intraperitoneal administration of ginseng total saponins (GTS) has antihyperalgesic effects in a rat model of incisional pain. The proinflammatory responses and reversal of the antihyperalgesic effect of GTS by N-methyl-d-aspartate (NMDA) or naloxone were also evaluated.

MATERIALS AND METHODS

Rats were injected intraperitoneally with 0.9% saline vehicle or various doses of GTS before or after a plantar incision. Paw withdrawal in response to application of the von Frey filament with the lowest bending force marked the mechanical withdrawal threshold (MWT). Blood samples were collected for the assessment of serum interleukin (IL)-1β and IL-6 levels. The IL levels were measured using an enzyme-linked immunosorbent assay kit. Rats were injected intraperitoneally with NMDA or naloxone before the GTS injection to assess the reversal of the antihyperalgesic effect of GTS.

RESULTS

The MWT measured 2 h after the plantar incision increased significantly after the postincision administration of 50, 100, or 200 mg/kg of GTS compared with the MWT at 2 h after plantar incision. The MWT also increased significantly after the preincision injection of 100 or 200 mg/kg of GTS compared with the MWT of the vehicle control. Administration of GTS suppressed the postincision rise in serum IL-1β levels and NMDA inhibited the increase in the MWT compared with GTS alone.

CONCLUSIONS

Intraperitoneal administration of GTS before or after surgery induces antihyperalgesic effects in a rat model of incisional pain. The effects on mechanical hyperalgesia may be associated with anti-inflammatory cytokines and NMDA signaling.

The effect of post-surgical neuroplasticity on the stability of systemic pain perception: a psychophysical study

BACKGROUND

Surgery-induced neuroplasticity at spinal and supra-spinal levels is assumed to evoke a clinical acute post-operative pain (cAPOP) experience, which is expressed by allodynia and/or hyperalgesia. It remains unclear whether the systemic pain perception measured outside the incision area remains unchanged and whether it is affected by the presence of cAPOP.

AIMS

This study explored whether the systemic perception of experimental pain would be altered towards hypersensitivity following elective gynecological surgery unmasked by opioids.

METHODS

A perioperative psychophysical evaluation of heat pain thresholds (HPT) and pain estimations were obtained in a remote bodily area before and after surgery among 35 women.

RESULTS

The ratings for both pain dimensions of intensity and unpleasantness remained stable following surgery. However, there was a reduction found in HPT the day after surgery (43.6 ± 2.2 °C to 42.2 ± 3.1 °C, p = 0.002). This reduction was associated with lower HPT measured before surgery (r = .56, p < 0.000) and with higher cAPOP intensity obtained at rest (r = -.44, p = 0.008).

CONCLUSIONS

This post-surgical allodynia, as reflected by the systemic enhancement of pain perception, may represent plasticity in the central pain pathways at the supra-spinal level. Pre-surgical assessment of a patient's pain perception profile may predict certain pain dimensions of post-surgical pain plasticity. The evaluation of individual pain profiles may contribute to a mechanism-based approach aimed to attenuate the cAPOP.

Effect of preincisional epidural fentanyl and bupivacaine on postthoracotomy pain and pulmonary function

BACKGROUND

This study attempts to determine whether preemptive thoracic epidural analgesia (TEA) initiated before surgical incision would reduce the severity of acute post-thoracotomy pain, its effects on pulmonary function and stress response.

METHODS

Forty patients undergoing posterolateral thoracotomy received TEA either before (preoperative-TEA group) or after (postoperative-TEA group) surgery. Postoperative analgesia was maintained with epidural infusion of bupivacaine and fentanyl. Pain scores, pulmonary functions, arterial blood gases, plasma glucose, cortisol levels and epidural fentanyl consumption were compared for 48 hours after surgery.

RESULTS

The preoperative-TEA group demonstrated significantly reduced pain scores at 2, 4, 8, 12, 24, and 48 hours at rest (p = 0.001, p = 0.002, p = 0.004, p = < 0.001, p = 0.006, and p = 0.001, respectively) and at 4, 8, 12, 24, 48 hours on coughing (p = 0.001, p = 0.001, p = 0.001, p = 0.001, p = 0.004, respectively), and a significant reduction in epidural fentanyl consumption (208.6 +/- 49.3 mL, versus 260 +/- 28.8 mL, p = 0.001). The preoperative-TEA group showed significant improvement in pulmonary functions as compared with the postoperative-TEA group (p < 0.05), except forced expiratory volume in one second at 24 hours (p = 0.061) and peak expiratory flow rate at 48 hours (p = 0.188). The postoperative-TEA treated patients were more likely to have a higher arterial carbon dioxide pressure at 4, 8, 12, and 24 hours (p = 0.017, p = 0.001, p = 0.003, p = 0.001), respectively. However, we could not demonstrate a statistical difference in oxygenation, cortisol, or glucose level.

CONCLUSIONS

Though preemptive TEA appeared to reduce the severity of acute pain, preserve pulmonary function, and reduce analgesic requirements, these statistically significant differences were not enough to conclude a clinical significant difference between groups.

Patients initially diagnosed as 'warm' or 'cold' CRPS 1 show differences in central sensory processing some eight years after diagnosis: a quantitative sensory testing study

We used quantitative sensory testing (QST) to gain further insight into mechanisms underlying pain in CRPS 1. Specific goals were: (1) to identify altered patterns of sensory processing some 8 years after diagnosis, (2) to document differences in sensory processing between 'warm' and 'cold' diagnostic subgroups, (3) to determine relationships between changed sensory processing and disease progression regarding pain. The study was performed on a cohort of patients (n=47) clinically diagnosed with CRPS 1 of one upper extremity approximately 8 years previously. Pain was quantified by VAS and MacGill Pain Questionnaire (MPQ), and all subjects underwent electrical and mechanical QST. Cold patients (n=13) had poorer MPQ scores than warm ones (n=34), and more pain on electrical stimulation. Their evoked pain increased with disease progression and correlated with clinical pain measures. For both diagnostic subgroups, thresholds to pressure pain were lower on the affected extremity and with disease progression. Eight years after original diagnosis, cold CRPS 1 patients have poorer clinical pain outcomes and show persistent signs of central sensitisation correlating with disease progression. The latter is not the case for warm CRPS 1 patients. Both diagnostic subgroups show greater pressure hyperalgesia on the affected limb and with disease progression. QST may prove useful in the subdiagnosis of CRPS 1 and in quantifying its progression, with both applications warranting further investigation for clinical and research use.

Bupivacaine versus lidocaine analgesia for neonatal circumcision

Background

Analgesia for neonatal circumcision was recently advocated for every male infant, and its use is considered essential by the American Academy of Pediatrics. We compared the post-operative analgesic quality of bupivacaine to that of lidocaine for achieving dorsal penile nerve block (DPNB) when performing neonatal circumcision.

Methods

Data were obtained from 38 neonates following neonatal circumcision. The infants had received DPNB analgesia with either lidocaine or bupivacaine. The outcome variable was the administration by the parents of acetaminophen during the ensuing 24 hours.

Results

Seventeen infants received lidocaine and 19 received bupivacaine DPNB. Ten infants in the lidocaine group (59%) were given acetaminophen following circumcision compared to only 3 (16%) in the bupivacaine group (P < 0.01). Regression analysis showed that the only significant variable associated with the need for acetaminophen was the use of lidocaine (R² = 20.6; P = 0.006).

Conclusion

DPNB with bupivacaine for neonatal circumcision apparently confers better analgesia than lidocaine as judged by the requirement of acetaminophen over the ensuing 24-hour period.

The efficacy of preemptive analgesia for acute postoperative pain management: a meta-analysis

Whether preemptive analgesic interventions are more effective than conventional regimens in managing acute postoperative pain remains controversial. We systematically searched for randomized controlled trials that specifically compared preoperative analgesic interventions with similar postoperative analgesic interventions via the same route. The retrieved reports were stratified according to five types of analgesic interventions: epidural analgesia, local anesthetic wound infiltration, systemic N-methyl-d-aspartic acid (NMDA) receptor antagonists, systemic nonsteroidal antiinflammatory drugs (NSAIDs), and systemic opioids. The primary outcome measures analyzed were the pain intensity scores, supplemental analgesic consumption, and time to first analgesic consumption. Sixty-six studies with data from 3261 patients were analyzed. Data were combined by using a fixed-effect model, and the effect size index (ES) used was the standardized mean difference. When the data from all three outcome measures were combined, the ES was most pronounced for preemptive administration of epidural analgesia (ES, 0.38; 95% confidence interval [CI], 0.28-0.47), local anesthetic wound infiltration (ES, 0.29; 95% CI, 0.17-0.40), and NSAID administration (ES, 0.39; 95% CI, 0.27-0.48). Whereas preemptive epidural analgesia resulted in consistent improvements in all three outcome variables, preemptive local anesthetic wound infiltration and NSAID administration improved analgesic consumption and time to first rescue analgesic request, but not postoperative pain scores. The least proof of efficacy was found in the case of systemic NMDA antagonist (ES, 0.09; 95% CI, -0.03 to 0.22) and opioid (ES, -0.10; 95% CI, -0.26 to 0.07) administration, and the results remain equivocal.

Preoperative ketorolac has a preemptive effect for postoperative third molar surgical pain

There is uncertainty regarding the role of preemptive analgesia in preventing postoperative pain. Most previous studies were of parallel design completed under general anesthesia with many confounding inter-patient's variables. The present study evaluated the efficacy of preemptive ketorolac in a crossover design in patients undergoing bilateral mandibular third molar surgery. This was a double blind, randomized, placebo-controlled study where 34 patients had each of their identical impacted mandibular third molars removed under local anesthesia on two occasions. Each patients acted as their own control; one side was pretreated with intravenous ketorolac 30 mg before surgery followed by placebo injection after surgery, and for the other side, the patient was given placebo injection before surgery and post-treated with intravenous ketorolac 30 mg after surgery. The difference in postoperative pain between pretreated and post-treated side in each patient was assessed by four primary end-points: pain intensity as measured by a 100-mm visual analogue scale hourly for 12 h, time to rescue analgesic, postoperative analgesic consumption, and patient's global assessment. Throughout the 12-h investigation period, patients reported significantly lower pain intensity scores in the ketorolac pretreated sides when compared with the post-treated sides (P = 0.003). Patients also reported a significantly longer time to rescue analgesic (8.9 h versus 6.9 h, P = 0.005), lesser postoperative analgesic consumption (P = 0.007) and better global assessment for the ketorolac pretreated sides (P = 0.01). Pretreatment with intravenous ketorolac has a preemptive effect for postoperative third molar surgery and extended the analgesia by approximately 2 h.

Preoperative nonsteroidal anti-inflammatory agents: review of the literature

Clinical studies that have used the third molar extraction model for acute post-operative dental pain have demonstrated the usefulness of nonsteroidal anti-inflammatory drugs (NSAIDs) as a preoperative analgesic. Despite this evidence, the use of preoperative analgesia is still not widespread. This article reviews the preoperative use of NSAIDs for reducing postoperative dental pain and includes recommendations to implement the use of NSAIDs in patients undergoing elective surgical interventions.

Non-opioid analgesia improves pain relief and decreases sedation after gastric bypass surgery

PURPOSE

Several non-opioid drugs have been shown to provide analgesia during and after surgery. We compared sevoflurane anesthesia with fentanyl analgesia to sevoflurane and non-opioid drug treatment for gastric bypass surgery and recovery.

METHODS

Thirty obese patients (body mass index > 50 kg.m(-2)) undergoing gastric bypass were randomized to receive sevoflurane anesthesia with either fentanyl or a non-opioid regimen including ketorolac, clonidine, lidocaine, ketamine, magnesium sulfate, and methylprednisolone. Morphine use by patient-controlled analgesia (PCA) pump and pain score measured by visual analogue scale were determined in the postanesthesia care unit (PACU) and for the first 16 hr after surgery. Sedation was evaluated in the PACU. Investigators assessing patient outcomes were blinded to the study group.

RESULTS

Fentanyl treated patients were more sedated in the PACU compared to the non-opioid group. Non-opioid treated patients required 5.2 +/- 2.6 mg.hr(-1) morphine by PCA during their stay in the PACU while patients anesthetized with fentanyl used 7.8 +/- 3.3 mg.hr(-1) (P < 0.05). Fentanyl and non-opioid treated patients showed no difference in pain score one or 16 hr after surgery.

CONCLUSION

Our results show that non-opioid analgesia produced pain relief and less sedation during recovery from gastric bypass surgery compared to fentanyl.

Human brain plasticity: an emerging view of the multiple substrates and mechanisms that cause cortical changes and related sensory dysfunctions after injuries of sensory inputs from the body

Injuries of peripheral inputs from the body cause sensory dysfunctions that are thought to be attributable to functional changes in cerebral cortical maps of the body. Prevalent theories propose that these cortical changes are explained by mechanisms that preeminently operate within cortex. This paper reviews findings from humans and other primates that point to a very different explanation, i.e. that injury triggers an immediately initiated, and subsequently continuing, progression of mechanisms that alter substrates at multiple subcortical as well as cortical locations. As part of this progression, peripheral injuries cause surprisingly rapid neurochemical/molecular, functional, and structural changes in peripheral, spinal, and brainstem substrates. Moreover, recent comparisons of extents of subcortical and cortical map changes indicate that initial subcortical changes can be more extensive than cortical changes, and that over time cortical and subcortical extents of change reach new balances. Mechanisms for these changes are ubiquitous in subcortical and cortical substrates and include neurochemical/molecular changes that cause functional alterations of normal excitation and inhibition, atrophy and degeneration of normal substrates, and sprouting of new connections. The result is that injuries that begin in the body become rapidly further embodied in reorganizational make-overs of the entire core of the somatosensory brain, from peripheral sensory neurons to cortex. We suggest that sensory dysfunctions after nerve, root, dorsal column (spinal), and amputation injuries can be viewed as diseases of reorganization in this core.

Preoperative back pain is associated with diverse manifestations of central neuroplasticity

Increased or decreased gain in central nervous system processing after surgery, i.e. neuroplasticity, may play an important role in postoperative pain. Identification of patient subgroups particularly vulnerable to either type of post-surgical neuroplasticity is thus of interest. Preoperative pain has also been suggested to increase vulnerability to post-surgical chronic pain complications due to central facilitation. To study if back pain preoperatively is associated with differences in central sensory processing, we measured transcutaneous electric sensation, pain detection and pain tolerance thresholds at the upper arm, lower back and lower leg in 52 consecutive patients scheduled for back surgery in a blinded, prospective fashion. Patients with no pain had significantly lower pain thresholds than patients with pain in the leg, and significantly higher pain thresholds than those with pain in the back. These results suggest that preoperative pain can induce diverse central neuroplastic changes, i.e. inhibition and facilitation, and that the nature of this neuroplasticity depends on the nature of the pain involved. The presence of facilitation may be the basis of the increased vulnerability described in some studies of patients with significant preoperative pain, whereas the implications of reduced pain sensitivity are less clear. The demonstration of neuroplasticity and its diversity are, however, likely to be of significant clinical relevance.