Breakthrough pain and rapid-onset opioids in patients with cancer pain: a narrative review.

Breakthrough pain is transitory pain that occurs despite the use of opioids for background pain control. Breakthrough pain occurs in 40% to 80% of patients with cancer pain. Despite effective analgesic therapy, patients and their caregivers often feel that their pain is not sufficiently controlled. Therefore, an improved understanding of breakthrough pain and its management is essential for all physicians caring for patients with cancer. This article reviews the definition, clinical manifestations, accurate diagnostic strategies, and optimal treatment options for breakthrough pain in patients with cancer. This review focuses on the efficacy and safety of rapid-onset opioids, which are the primary rescue drugs for breakthrough pain.

Trends in the prescription of opioids and gabapentinoids in patients with failed back surgery syndrome in Korea: a population-based study.

Background: Failed back surgery syndrome (FBSS) is a chronic condition that is characterized by persistent back pain following one or more spinal surgeries. Pharmacological interventions, such as the use of opioids and gabapentinoids, are frequently used in the treatment of FBSS. However, prolonged and excessive use of these medications can lead to dependence and adverse effects. This study investigates trends in opioid and gabapentinoid prescriptions among patients with FBSS in Korea from 2016 to 2020. Methods: Data from the Health Insurance and Review Agency were analyzed, and claims listing FBSS were selected for the study. Prescription patterns of opioids and gabapentinoids were classified based on the number of days prescribed per year. Results: Of the 390,095 patients diagnosed with FBSS, 41.6% of the patients were prescribed gabapentinoids, and 42.0% of them were prescribed opioids, while 10.6% of the patients were classified as long-term gabapentinoid users, 11.4% as long-term opioid users, and 7.4% of the patients were found to have long-term prescriptions for both drugs. The proportion of patients who received both gabapentinoid and opioid prescriptions increased annually. The doses of opioids prescribed have also increased along with the increase in the number of patients receiving opioid prescriptions. Conclusions: The prescription rates of opioids and gabapentinoids among patients with FBSS in Korea continue to increase steadily, posing potential risks of addiction and adverse effects. Further research is needed to better understand the actual status of addiction in patients with FBSS.

Effect of Dexmedetomidine Preconditioning on Hepatic Ischemia-Reperfusion Injury in Acute Hyperglycemic Rats.

BACKGROUND: Acute hyperglycemia frequently occurs in stressful situations, including liver transplantation or hepatic surgery, which may affect the protective effects of dexmedetomidine preconditioning and increase postoperative mortality. Therefore, this study aimed to investigate the effects of dexmedetomidine on hepatic ischemia-reperfusion injury in acute hyperglycemia. METHODS: Thirty-six Sprague-Dawley rats were randomly assigned to 6 groups, including a combination between 2 glycemic (normo- and hyperglycemia) and 3 ischemia-reperfusion conditions (sham, ischemia-reperfusion only, and dexmedetomidine plus ischemia-reperfusion). Dexmedetomidine 70 µg/kg was preconditioned 30 minutes before ischemic injury. After 6 hours of reperfusion, serum aminotransferase levels were measured to confirm the hepatic tissue injury. Furthermore, inflammatory (nuclear factor-κb, tumor necrosis factor-α, and interleukin-6) and oxidative stress markers (malondialdehyde and superoxide dismutase) were detected. RESULTS: Ischemia-reperfusion injury significantly increased the serum levels of aminotransferase and inflammatory and oxidative stress markers. These ischemia-reperfusion-induced changes were further exacerbated in hyperglycemia and were significantly attenuated by dexmedetomidine preconditioning. However, the effects of dexmedetomidine in hyperglycemia were lesser than those in normoglycemia (P < .05 for aminotransferases, inflammatory markers, malondialdehyde, and superoxide dismutase). CONCLUSIONS: These findings suggest that the protective effects of dexmedetomidine preconditioning may be intact against hepatic ischemia-reperfusion injury in acute hyperglycemia. Although its effects appeared to be relatively reduced, this may be because of the increase in oxidative stress and inflammatory response caused by acute hyperglycemia. To determine whether the effects of dexmedetomidine itself would be impaired in hyperglycemia, further study is needed.

Comparison of a Non-Opioid Multimodal Analgesia Protocol with Opioid-Based Patient-Controlled Analgesia for Pain Control Following Robot-Assisted Radical Prostatectomy: A Randomized, Non-Inferiority Trial.

Background: Opioid use after surgery is a potential contributor to the opioid epidemic. An adequate pain control method after surgery while minimizing opioid exposure is needed. This study aimed to compare the effect of non-opioid multimodal analgesia (NOMA) protocol with opioid-based patient-controlled analgesia (PCA) for pain relief after robot-assisted radical prostatectomy (RARP). Methods: This prospective randomized, open, non-inferiority trial included 80 patients scheduled for RARP. The NOMA group received pregabalin, paracetamol, bilateral quadratus lumborum block, and pudendal nerve block. PCA group received PCA. Pain scores, postoperative nausea and vomiting, opioid requirements, and quality of recovery were recorded 48 hours after surgery. Results: We found no significant differences in pain scores. The mean difference in pain score during rest at 24 h was 0.5 (95% CI -0.5 to 2.0). This result demonstrated the non-inferiority of NOMA protocol to PCA at our non-inferiority margin (-1). In addition, 23 patients in the NOMA group did not receive any opioid agonist for 48 h after surgery. Recovery of bowel function was also faster in the NOMA group than in the PCA group (25.0 hours vs 33.4 hours, p = 0.01). Limitations: We did not evaluate whether our NOMA protocol could decrease the incidence of new continuous opioid use after surgery. Conclusion: NOMA protocol successfully controlled postoperative pain and was non-inferior to morphine-based PCA regarding patient-reported pain intensity. It also promoted recovery of bowel function and decreased postoperative nausea and vomiting.

Comparison of the Analgesic Efficacy of Opioid-Sparing Multimodal Analgesia and Morphine-Based Patient-Controlled Analgesia in Minimally Invasive Surgery for Colorectal Cancer.

BACKGROUND: A multimodal analgesia (MMA) protocol has shown the effect of postoperative pain control and reduced the postoperative opioid consumption. However, it was questionable whether MMA could replace opioid-based patient-controlled analgesia (PCA) for postoperative pain control. Therefore, this study aimed to investigate whether an MMA protocol is non-inferior to opioid-based PCA for pain management after a minimally invasive colorectal cancer surgery. METHODS: A randomized, open-label, non-inferiority clinical trial was conducted on patients undergoing laparoscopic or robotic resection of colorectal cancer. The patients were randomly assigned to either the PCA or MMA group. The MMA protocol included pregabalin, tramadol, wound infiltration, and transversus abdominis plane block. The primary outcome was the numeric rating scale (NRS) score for pain at rest 24 h postoperatively. RESULTS: Ninety-seven patients were included in the intention-to-treat analysis. The mean difference in NRS score at rest at 24 h was 0.25 (95% confidence interval, - 0.61 to 1.11). This result demonstrated the non-inferiority of MMA to PCA in our non-inferiority margin (- 1). Compared with the PCA group, the median remifentanil dose (996 vs. 654 µg; p < 0.001) and time in the post-anesthesia care unit (35 vs. 25 min; p < 0.001) were significantly less in the MMA group. CONCLUSIONS: Our MMA protocol successfully controlled postoperative pain and was non-inferior to morphine-based PCA based on patient-reported pain intensity, with no significant increase in adverse events. These results will help construct a strategy to reduce conventional opioid prescriptions for pain management after a minimally invasive colorectal cancer surgery. Trial Registration Number Trial Registration Clinical Research Information Service Identifier: KCT0002593.

Infection prevention measures and outcomes for surgical patients during a COVID-19 outbreak in a tertiary hospital in Daegu, South Korea: a retrospective observational study.

BACKGRUOUND: The first large coronavirus disease 2019 (COVID-19) outbreak outside China occurred in Daegu. In response, we developed infection prevention measures for surgical patients during the outbreak at our hospital and retrospectively reviewed the outcomes of COVID-19-related surgical patients. METHODS: We reviewed the medical records of 118 COVID-19-related surgical patients and monitored their clinical outcomes until March 31, 2021. We also interviewed healthcare workers who participated in their perioperative care at Kyungpook National University Chilgok Hospital. The perioperative management guidelines for COVID-19-related patients were prepared through multidisciplinary discussions, including the infection control department, surgical departments, and anesthesiology department before and during the COVID-19 outbreak. RESULTS: One standard operating room was temporarily converted to a negative-pressure room by increasing the exhaust air volume, creating a relative pressure of -11.3 Pa. The healthcare workers were equipped with personal protective equipment according to the patient's classification of the risk of COVID-19 transmission. The 118 COVID-19-related patients underwent emergent surgery in the negative-pressure room, including three COVID-19-confirmed patients and five COVID-19-exposed patients. CONCLUSION: All surgeries of the COVID-19-related patients were performed without specific adverse events or perioperative COVID-19 transmission. Our experience setting up a negative-pressure operating room and conservative perioperative protocol to prevent COVID-19 transmission will help plan and execute infection control measures in the future.

Transversus abdominis plane block for lumboperitoneal shunt surgery in idiopathic normal pressure hydrocephalus: a case report.

The transversus abdominis plane (TAP) block is an ideal pain control method used in surgeries that require abdominal wall incisions through the injection of an anesthetic solution into the plane between the internal oblique muscle and transversus abdominis muscle. Herein, we report an 83-year-old man who was diagnosed with idiopathic normal pressure hydrocephalus (iNPH) and underwent lumboperitoneal shunt surgery (LPS). The TAP block was performed before LPS, and the numerical rating scale for pain was 0 at day 1 after the surgery. The patient was discharged early at day 3 after surgery despite the patient being extremely old, as he reported quick relief from the postoperative abdominal pain. The TAP block can hence be considered for use before LPS in elderly patients with iNPH.

Translation and Validation of the Korean Version of the Postoperative Quality of Recovery Score QoR-15.

Quality of recovery after anesthesia is an important measure of the early postoperative health status of patients. The Quality of Recovery-15 (QoR-15) questionnaire is a self-rated questionnaire used to assess the quality of postoperative recovery. This study is aimed at translating and validating the Korean version of QoR-15 (QoR-15K). One hundred fifty patients were included in this study. We translated the original version of QoR-15 into QoR-15K and evaluated its validity, reliability, responsiveness, and clinical feasibility. QoR-15K showed acceptable criterion, structure, and construct validities. Reliability was verified using Cronbach's α (0.856), standard error of measurement (10.78), split-half reliability (0.831), test-retest reliability (ρ = 0.945, P ≤ 0.001), and intraclass correlation test-retest (ρ = 0.903, P ≤ 0.001). These results represent an acceptable reliability. Responsiveness was verified using Cohen's effect size (1.39), standardized response mean (1.03), and the correlation between QoR-15K score and duration of anesthesia (ρ = -0.197, P = 0.016). These results show acceptable responsiveness. The mean ± standard deviation time to complete QoR-15K was 138.1 ± 30.7 s. QoR-15K was rated more than adequate on the COnsensus-based Standards for the selection of health Measurement INstruments checklist. In conclusion, QoR-15K shows acceptable validity, reliability, responsiveness, and clinical feasibility and may help evaluate postoperative quality of recovery in Korean populations.

Analgesic Effect of Ultrasound-Guided Preoperative Unilateral Lateral Quadratus Lumborum Block for Laparoscopic Nephrectomy: A Randomized, Double-Blinded, Controlled Trial.

PURPOSE: The quadratus lumborum block (QLB) is a relatively new regional analgesic technique that could provide analgesia to the abdominal wall and reduce postoperative opioid consumption. We investigated the opioid-sparing effect of a unilateral lateral QLB in laparoscopic nephrectomy. PATIENTS AND METHODS: A total of 60 patients undergoing laparoscopic nephrectomy were included in the study. Patients were randomized into two groups as QLB and control group. QLB group received QLB with 25mL 0.25% ropivacaine, and the control group received 25mL 0.9% saline at anterolateral border of quadratus lumborum muscle preoperatively. Opioid consumption and the pain intensity at rest and on movement were measured at 2nd, 6th, 24th, and 48th hour postoperatively. We also assessed the time to first flatus to measure the extent of paralytic ileus and the quality of recovery-15 (QoR-15) questionnaire. RESULTS: Postoperative opioid consumption was significantly lower in the QLB group than in the control group at 6, 24, and 48h after surgery (P < 0.05). The pain intensity at rest and on movement was significantly lower in the QLB group than in the control group during the first 24 hours after surgery (P < 0.05). The incidence of postoperative nausea and vomiting, time to first flatus, and QoR-15 score did not show significant differences. CONCLUSION: Preoperative unilateral QLB successfully decreased postoperative pain and opioid consumption after laparoscopic nephrectomy and could be an option for analgesia after laparoscopic nephrectomy.

Effect of dexmedetomidine on the development of mechanical allodynia and central sensitization in chronic post-ischemia pain rats.

PURPOSE: Complex regional pain syndrome type 1 (CRPS I) is an intractable neuropathic pain syndrome. Chronic post-ischemia pain (CPIP) model is an animal model of CRPS I which is produced by ischemia-reperfusion (IR) injury of the hind limb. Dexmedetomidine (DEX) is a selective and potent α2 adrenergic receptor agonist with analgesic and protective effects following an IR injury. We hypothesized that DEX protects the development of mechanical allodynia and central sensitization in CRPS I. Therefore, we evaluated the dose-related protective effect of DEX in a CPIP model. METHODS: We divided 45 rats into five groups: sham, CPIP, CPIP + DEX 10 µg/kg, CPIP + DEX 50 µg/kg, and CPIP + DEX 100 µg/kg. Rats in the sham group underwent sham surgery, and the other rats received CPIP injury. One hour before reperfusion or end of sham surgery, normal saline was injected into the rats in the sham and CPIP groups, and DEX (designated dose) was injected into the rats in the other groups. All rats were evaluated for the withdrawal threshold of both hind paws before surgery and 1, 3, and 7 days after surgery. Phosphorylation of N-methyl-d-aspartate receptor subunits (pGluN1) and phosphorylation of extracellular signal-regulated kinases (pERK) in the spinal cord were measured 3 days after surgery. RESULTS: Administration of DEX before reperfusion showed a significant increase in the withdrawal threshold in both hind paws and a significant decrease of the expressions of pGluN1 and pERK in CPIP rats dose dependently (P<0.05). CONCLUSION: DEX may inhibit the development of mechanical allodynia and central sensitization in CPIP rats.

Effects of Glutathione on Mechanical Allodynia and Central Sensitization in Chronic Postischemic Pain Rats.

Background: The chronic postischemia pain (CPIP) model is an animal model using ischemia/reperfusion injury that mimics the symptoms of complex regional pain syndrome type I. Glutathione (GSH) prevents ischemia/reperfusion injury by scavenging free radicals. We conducted this study to investigate the protective effect of GSH in CPIP rats via changes of mechanical allodynia and phospholyration of the N-methyl-D-aspartate receptor subunit GluN1. Methods: We divided 45 rats into 5 groups: sham, CPIP, CPIP + GSH 100 mg/kg, CPIP + GSH 200 mg/kg, and CPIP + GSH 500 mg/kg. Rats in the sham and CPIP groups received normal saline and rats in the other groups received GSH at the designated doses thirty minutes prior to reperfusion. Withdrawal thresholds were evaluated before sugery as well as 1, 3, and 7 days after surgery. pGluN1 level in the spinal cord was also measured. Results: GSH treated rats show a significant increase in the withdrawal thresholds of both hind paws as compared with the CPIP group dose-dependently. The expression of pGluN1 in the GSH treated rats significantly decreased as compared to the CPIP group (all P < 0.05). Conclusion: These findings suggest that GSH inhibited the development of mechanical allodynia and central sensitization in CPIP rats.

Comparison of Analgesic Efficacy of Laparoscope-Assisted and Ultrasound-Guided Transversus Abdominis Plane Block after Laparoscopic Colorectal Operation: A Randomized, Single-Blind, Non-Inferiority Trial.

BACKGROUND: Transversus abdominis plane (TAP) block has been used as a component of multimodal analgesia after abdominal operation. We introduced a new laparoscope-assisted TAP (LTAP) block technique using intraperitoneal injection and compared its analgesic effect with that of an ultrasound-guided TAP (UTAP) block in terms of postoperative pain control. STUDY DESIGN: A prospective, randomized, single-blinded non-inferiority clinical trial was conducted with patients undergoing elective laparoscopic colectomy for colon cancer. Eighty patients were randomly assigned (1:1 ratio) to the UTAP and LTAP groups. At the end of the operation, opioid consumption and numeric rating scores (NRS; 0 [no pain] to 10 [worst pain]) of pain were recorded at 2, 6, 24, and 48 hours postoperatively and were compared between the groups. The primary end point was pain NRS during rest at 24 hours after operation. RESULTS: Thirty-eight patients in the LTAP group and 35 patients in the UTAP group completed the study protocol. We found no significant difference in mean ± SD pain NRS during rest at 24 hours between the LTAP group (3.90 ± 1.7) and the UTAP group (4.5 ± 1.9). The mean difference in pain NRS during rest at 24 hours was 0.57 (95% CI -0.26 to 1.41). Because the lower boundary of a 95% CI for the differences in pain NRS was > -1, non-inferiority was established. There was no significant difference between the groups in NRS pain during rest, NRS pain on movement, and postoperative morphine consumption during the 48 hours after operation. CONCLUSIONS: These results show our new LTAP block technique was non-inferior to the ultrasound-guided technique in providing a TAP block after laparoscopic colorectal operation.

Effect of Intravenous High Dose Vitamin C on Postoperative Pain and Morphine Use after Laparoscopic Colectomy: A Randomized Controlled Trial.

Background and Objective. Vitamin C has antioxidant, neuroprotective, and neuromodulating effects. Recently, it showed antinociceptive effect as a result of the antioxidant properties. Therefore, we designed this study to assess the effect of intravenous vitamin C on opiate consumption and pain in patients undergoing laparoscopic colectomy. Methods. A total of 100 patients were enrolled and allocated to receive 50 mg/kg vitamin C or placebo by intravenous infusion immediately after induction of anesthesia. Morphine consumption and scores of pain were assessed at 2, 6, and 24 h after completion of surgery. Results. There were 97 patients included in the analysis. Patients who received vitamin C had higher plasma concentrations of vitamin C at the end of surgery, significantly lower morphine consumption at the 2 h after end of surgery, and significantly lower pain scores at rest during first 24 h postoperatively. There was no significant difference between groups in side effects, fatigue score, or pain score during cough. Conclusion. This study shows high dose vitamin C infusion decreased postoperative pain during the first 24 h and reduced morphine consumption in the early postoperative period. Additional research needed to examine whether higher doses of vitamin C and longer infusion times can amplify these effects.

Inhibition of reactive oxygen species downregulates the MAPK pathway in rat spinal cord after limb ischemia reperfusion injury.

INTRODUCTION: We examined the activity of mitogen-activated protein kinase (MAPK) family members, extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38, in rats pinal cord after hind limb ischemia reperfusion (IR) and analyzed the role of reactive oxygen species (ROS) as mediators of MAPK signaling under these conditions. METHODS: In experiment 1, hind limb IR rats were treated intraperitoneally with one of following agents at 30 min before reperfusion: allopurinol (4, 40 mg/kg), superoxide dismutase (SOD, 4000 U/kg), N-nitro-l-arginine methyl ester (l-NAME, 10 mg/kg), or SOD (4000 U/kg) + l-NAME (10 mg/kg). In experiment 2, 5,10,15,20-tetrakis (N-methyl-4'-pyridyl) porphyrinato iron (III) (FeTMPyP) was administered intraperitoneally (1, 3, or 10 mg/kg) 30 min before reperfusion. After 3 d reperfusion period, the spinal cord (L4-6) was harvested to investigate MAPK signaling activity. RESULTS: In experiment 1, p-ERK and p-JNK levels were significantly higher in the IR group than sham group. Administration of allopurinol, SOD, l-NAME, or SOD + l-NAME significantly reduced the IR-induced increase in p-ERK and p-JNK levels. There were no significant differences in p-p38 levels. In experiment 2, FeTMPyP significantly reduced the IR-induced increase in p-ERK and p-JNK levels in a dose-dependent manner. CONCLUSIONS: Activation of ERK and JNK in the spinal cord was induced by hind limb IR and was not accompanied by p38 activation. IR-induced MAPK phosphorylation was reduced by inhibition of superoxide, nitric oxide, and peroxynitrite, indicating that ROS produced by hind limb IR mediate the activation of these signaling pathways in the spinal cord, potentially affecting distant organs.

Effects of stellate ganglion block on sedation as assessed by bispectral index in normal healthy volunteers.

BACKGROUND: The sympathetic nervous system plays an important role in the arousal response. Recently, the stellate ganglion block (SGB) was found to effectively treat anxiety and night awakening in humans and decrease electroencephalogram (EEG) indices of arousal responses in rat. But, the role of the sympathetic block in human arousal responses has not yet been studied. OBJECTIVE: We performed this prospective, double-blinded, controlled volunteer study to investigate the sedative effects and bispectral index (BIS) changes of SGB. STUDY DESIGN: A randomized, double-blind trial. SETTING: Single academic medical center. METHODS: This study was approved by the Ethics Committee of Kyungpook National University Hospital (ref: KNUH-10-1081) and registered with CRiS (Clinical Research Information Service, http://cris.cdc.go.kr, ref: KCT0000036, 2010. 9.24). Twenty healthy volunteers were enrolled in this study. The volunteers were randomly assigned to one of 2 groups: the SGB group (n = 10) and the sham group (n =10). Volunteers in SGB group received SGB and volunteers in the sham group received a sham procedure. BIS value, heart rate, and blood pressure were measured before and 5, 10, 20, and 30 minutes after the procedure. Observer's Assessment of Alertness/Sedation (OAA/S) scores were assessed before and 10 and 30 minutes after the intervention. RESULTS: In the SGB group, BIS values and OAA/S scores significantly decreased after the intervention as compared to baseline (P < 0.05). The values were also significantly decreased in the SGB group when compared to the values in sham group after the intervention (P < 0.05). There was a significant change of mean blood pressure 10 to 30 minutes after SGB (P < 0.05). There were no differences in heart rate during study period between groups. LIMITATIONS: This study is limited by a relatively small sample size. CONCLUSIONS: This study showed that SGB has a sedative effect in normal healthy volunteers, as evidenced by decreased OAA/S scores and BIS values.

Can intravenous patient-controlled analgesia be omitted in patients undergoing laparoscopic surgery for colorectal cancer?

PURPOSE: Opioid-based intravenous patient-controlled analgesia (IV-PCA) is a popular method of postoperative analgesia, but many patients suffer from PCA-related complications. We hypothesized that PCA was not essential in patients undergoing major abdominal surgery by minimal invasive approach. METHODS: Between February 2013 and August 2013, 297 patients undergoing laparoscopic surgery for colorectal cancer were included in this retrospective comparative study. The PCA group received conventional opioid-based PCA postoperatively, and the non-PCA group received intravenous anti-inflammatory drugs (Tramadol) as necessary. Patients reported their postoperative pain using a subjective visual analogue scale (VAS). The PCA-related adverse effects and frequency of rescue analgesia were evaluated, and the recovery rates were measured. RESULTS: Patients in the PCA group experienced less postoperative pain on days 4 and 5 after surgery than those in the non-PCA group (mean [SD] VAS: day 4, 6.2 [0.3] vs. 7.0 [0.3], P = 0.010; and day 5, 5.1 [0.2] vs. 5.5 [0.2], P = 0.030, respectively). Fewer patients in the non-PCA group required additional parenteral analgesia (41 of 93 patients vs. 53 of 75 patients, respectively), and none in the non-PCA group required rescue PCA postoperatively. The incidence of postoperative nausea and vomiting was significantly higher in the non-PCA group than in the PCA group (P < 0.001). The mean (range) length of hospital stay was shorter in the non-PCA group (7.9 [6-10] days vs. 8.7 [7-16] days, respectively, P = 0.03). CONCLUSION: Our Results suggest that IV-PCA may not be necessary in selected patients those who underwent minimal invasive surgery for colorectal cancer.

Effect of local wound infiltration and transversus abdominis plane block on morphine use after laparoscopic colectomy: a nonrandomized, single-blind prospective study.

BACKGROUND: Recently, nonopioid-based treatment modalities have been used to improve analgesia and decrease opioid-related side effects after surgery. Transversus abdominis plane (TAP) block and local infiltration of the surgical wound are commonly used multimodal analgesia techniques after abdominal surgery; however, few studies have compared the effectiveness of a TAP block with that of local infiltration of surgical wounds in patients who have undergone laparoscopic colorectal surgery. MATERIALS AND METHODS: Sixty patients undergoing laparoscopic colorectal surgery participated in this prospective comparative study. All patients were allocated to 1 of 2 groups as follows: the TAP group or the infiltration group. Patients in the TAP group received bilateral TAP blocks at the end of the surgery. Patients in the infiltration group received local infiltration of anesthetics in the surgical wounds after closure of the peritoneum. All patients received postoperative analgesia with morphine as a patient-controlled analgesia. Opioid consumption and pain scores were recorded at 2, 6, 24, and 48 h after the operation. RESULTS: The characteristics of patients in the TAP group (n = 30) and local infiltration group (n = 29) were comparable. Pain scores while coughing and at rest were not different between the two groups. Postoperative morphine use was significantly reduced in the TAP group compared with that in the local infiltration group at 2-6 h (2.9 ± 1.9 mg versus 4.5 ± 3.2 mg, P = 0.02), 6-24 h (5.5 ± 3.3 mg versus 10.2 ± 8.4 mg, P = 0.00), the first 24 h (16.6 ± 6.6 mg versus 24.0 ± 9.7 mg), and 48 h (23.6 ± 8.2 mg versus 31.8 ± 12.5 mg, P = 0.00). No differences in rescue analgesic use or side effects were noted between the groups. CONCLUSIONS: Compared with local anesthetic infiltration, bilateral TAP blocks decreased the cumulative morphine use at 24 h and 48 h postoperatively in patients who had undergone laparoscopic colorectal surgery.

A peroxynitrite decomposition catalyst prevents mechanical allodynia and NMDA receptor activation in the hind-paw ischemia reperfusion injury rats.

The contributions of superoxide and nitric oxide to ischemia/reperfusion (I/R)-induced neuropathic pain have previously been demonstrated in an animal model that mimics the symptoms of complex regional pain syndrome type I (CRPS I). Targeting peroxynitrite, which is the product of their interaction, may provide effective treatments for I/R-induced neuropathic pain. In this study, the effect of the peroxynitrite decomposition catalyst FeTMPyP [5,10,15,20-tetrakis (N-methyl-4'-pyridyl)porphyrinato iron (III)], administered at doses of 1, 3 and 10 mg/kg via intraperitoneal injection 30 min prior to reperfusion, was evaluated in rats with chronic post-ischemic pain. The pain behavior of the rats was tested with a von Frey filament. Phosphorylation of N-methyl-D-aspartate (NMDA) receptors in the L4/6 section of the spinal cord was measured on the third day following reperfusion by western blotting. The rats treated with 3 or 10 mg/kg FeTMPyP demonstrated significant increases in their paw withdrawal thresholds and decreased levels of phosphorylated NMDA receptor subunit 1 compared with those of the vehicle group (all P<0.001). These findings suggest that nitrosative stress, specifically that associated with peroxynitrite, may be involved in the mechanical allodynia and central sensitization that are associated with CRPS I and may provide a rationale for CRPS I treatment strategies using peroxynitrite decomposition catalysts.

The effects of stellate ganglion block on the electroencephalogram in rats.

PURPOSE: It is reported that the sympathetic nervous system may play an important role in the arousal response. The present study evaluated the effect of stellate ganglion block (SGB) on electroencephalogram (EEG) activity in rats. MATERIALS AND METHODS: Adult male Sprague-Dawley rats were divided into two groups: SGB (n = 10) or intramuscular (IM, n = 10) injection was performed with 0.2 ml 0.25 % bupivacaine. The spectral edge frequency 95 % (SEF 95 %), median frequency (MF), beta to theta ratio (BTR), and beta to delta ratio (BDR) were estimated 30 min before bupivacaine injection and 15, 20, 25, 30, 45, 55, and 100 min after SGB or IM injection. RESULTS: Ipsilateral ptosis occurred in all the rats that underwent SGB but did not occur in the IM group. Significant decrease of the 95 % SEF value, MF, BTR, and BDR was observed from 15 to 45 min after SGB compared with those of the IM group, respectively (p < 0.05). CONCLUSIONS: SGB with 0.2 ml 0.25 % bupivacaine significantly decreased EEG activities in rats. These results suggest that SGB can induce a sedative effect in rats. Further studies are required to investigate the behavioral tests for sedative effects of SGB.