Comparison of block characteristics and outcomes in opioid-free and opioid-based thoracic continuous spinal anaesthesia in patients undergoing major abdominal surgery: A double-blinded randomised controlled trial.

Background and Aims: Thoracic continuous spinal anaesthesia (TCSA) is emerging as the sole anaesthetic for major abdominal surgery due to its better perioperative outcomes. This study was designed to evaluate block characteristics and outcomes in 'opioid-free' and 'opioid-based' TCSA. Methods: After ethical approval, trial registration and written informed consent, 50 adult patients undergoing major abdominal surgery were randomised into 'opioid-free' (bupivacaine alone) and 'opioid-based' (bupivacaine with fentanyl) groups. After confirmation of T4-L1 dermatome level of spinal anaesthesia, sedation by intravenous (IV) midazolam (0.02-0.05 mg/kg), ketamine (0.25 mg/kg) and dexmedetomidine (bolus dose of 1 µg/kg IV over 10 min followed by 0.2-0.7 µg/kg/h infusion) were started. The primary outcome measured was postoperative pain scores for 72 h in both groups. The secondary objectives were rescue opioid requirement, and the dose of bupivacaine required to achieve T4 level. Data were compared using the two-sided Student t-test, Mann-Whitney and Fisher's exact tests. Results: The 'opioid-based' group performed significantly better compared with the 'opioid-free' group concerning pain scores at rest at 0 h (P = 0.023), 18 h (P = 0.023) and 24 h (P = 0.016) postoperatively, decreased intrathecal bupivacaine requirement [(induction (P = 0.012) and maintenance (P = 0.031)], postoperative rescue fentanyl requirement (P = 0.018) and patient satisfaction (P = 0.032) at the cost of increased postoperative nausea and vomiting (P = 0.049). Conclusion: The 'opioid-based' TCSA provided better postoperative analgesia with significantly lesser postoperative pain scores when compared to the 'opioid-free' group in patients undergoing major abdominal surgery.

Patient and procedure characteristics associated with postoperative pain after prophylactic versus therapeutic ambulatory bilateral breast surgery.

BACKGROUND AND OBJECTIVES: We investigated whether age, body mass index (BMI), and tissue expander placement were related to postoperative opioid requirement for patients undergoing therapeutic versus prophylactic breast surgery. METHODS: Postoperative opioid consumption was evaluated for patients who underwent bilateral mastectomy with immediate implant-based reconstruction at a freestanding ambulatory cancer surgery center between 2016 and 2021. Ordinal regression tested whether surgical indication was associated with increased postoperative opioid requirements after adjusting for age, BMI, and tissue expander placement. RESULTS: Of 2447 patients, 6% underwent prophylactic surgeries. Therapeutic mastectomy patients had lower postoperative opioid requirement (OR = 0.67; 95% CI: 0.50-0.91; p = 0.030), but this was not significant after adjusting for covariates (OR = 0.75; 95% CI: 0.53-1.07; p = 0.2). Opioid use increased with higher BMI (OR = 1.06; 95% CI: 1.05-1.08; p < 0.001) and decreased with age (OR = 0.97; 95% CI: 0.96-0.98; p < 0.001) with therapeutic mastectomy patients being older (median 46 vs. 39). The subpectoral tissue expander group had nearly double the postoperative opioid requirement compared to prepectoral placement (OR = 1.86; 95% CI: 1.55-2.23; p < 0.001). CONCLUSIONS: Increased postoperative opioid requirement in women undergoing prophylactic procedures is best explained by age. Mastectomy patients should be counseled similarly about postoperative pain irrespective of indication. A larger prophylactic mastectomy sample is required to provide more precise estimates.

Genetic Polymorphisms of ENPP2 Are Possibly Associated with Pain Severity and Opioid Dose Requirements in Patients with Inflammatory Pain Conditions: Clinical Observation Study.

Autotaxin, encoded by the ENPP2 gene, is a known key element of neuropathic pain; however, its involvement in nociceptive pain processing remains unclear. We explored the associations between postoperative pain intensity, 24-h postoperative opioid dose requirements, and 93 ENNP2-gene single-nucleotide polymorphisms (SNPs) in 362 healthy patients who underwent cosmetic surgery using the dominant, recessive, and genotypic models. Next, we validated the associations between relevant SNPs on the one hand and pain intensity and daily opioid dosages on the other in 89 patients with cancer-related pain. In this validation study, a Bonferroni correction for multiplicity was applied on all relevant SNPs of the ENPP2 gene and their respective models. In the exploratory study, three models of two SNPs (rs7832704 and rs2249015) were significantly associated with postoperative opioid doses, although the postoperative pain intensity was comparable. In the validation study, the three models of the two SNPs were also significantly associated with cancer pain intensity (p < 0.017). Patients with a minor allele homozygosity complained of more severe pain compared with patients with other genotypes when using comparable daily opioid doses. Our findings might suggest that autotaxin is associated with nociceptive pain processing and the regulation of opioid requirements.

Does surgical plethysmographic index-guided analgesia affect opioid requirement and extubation time? A systematic review and meta-analysis.

PURPOSE: This meta-analysis of all relevant clinical trials investigated surgical plethysmographic index (SPI)-guided analgesia's efficacy under general anesthesia for perioperative opioid requirement and emergence time after anesthesia. METHODS: PubMed, Embase, Web of Science, and Cochrane Library were searched up to January 2022 to identify clinical trials comparing SPI-guided and conventional clinical practice for patients who underwent general anesthesia. With the random-effects model, we compared intraoperative opioid consumption, emergence time, postoperative pain, analgesia requirement, and incidence of postoperative nausea and vomiting (PONV). RESULTS: Thirteen randomized controlled trials (RCTs) (n = 1314) met our selection criteria. The overall pooled effect sizes of all RCTs indicated that SPI-guided analgesia could not significantly reduce opioid consumption during general anesthesia. SPI-guided analgesia accompanied with hypnosis monitoring could decrease intraoperative opioid consumption (standardized mean difference [SMD] - 0.31, 95% confidence interval [CI] - 0.63 to 0.00) more effectively than SPI without hypnosis monitoring (SMD 1.03, 95% CI 0.53-1.53), showing a significant difference (p < 0.001). SPI-guided analgesia could significantly shorten the emergence time, whether assessed by extubation time (SMD - 0.36, 95% CI - 0.70 to - 0.03, p < 0.05, I2 = 67%) or eye-opening time (SMD - 0.40, 95% CI - 0.63 to - 0.18, p < 0.001, I2 = 54%). SPI-guided analgesia did not affect the incidence of PONV, postoperative pain, and analgesia management. CONCLUSION: SPI-guided analgesia under general anesthesia could enhance recovery after surgery without increasing the postoperative complication risk. However, it did not affect intraoperative opioid requirement. Notably, SPI-guided analgesia with hypnosis monitoring could effectively reduce intraoperative opioid requirement.

ABO blood group is not a predictive factor for the amount of early opioid consumption in postanesthesia care unit: a prospective cohort study in 3,316 patients.

BACKGROUND: Immediate postoperative pain in the postanesthesia care unit (PACU) is common. Titration of opioid is the most popular strategy for controlling early postoperative pain. ABO blood group has been found to be associated with pain perception. We aimed to find the factors including ABO blood group for predicting the amount of opioid requirement in PACU. METHODS: This prospective cohort study was performed in 3316 patients who underwent various kinds of anesthetic techniques and received immediate postoperative care in PACU. Preoperative, intraoperative and PACU data were collected. A directed acyclic graph (DAG) representing the hypothesized causal pathways of preoperative, intraoperative and PACU data were compiled prior to conducting multinomial logistic regression analysis. Statistical significance in all models was defined as a P-value < 0.05. RESULTS: Female sex, body mass index, preoperative use of gabapentin, preoperative anxiety score, anesthetic techniques, type of operation, amount of consumed intraoperative opioids, intraoperative use of paracetamol, parecoxib and ondansetron, duration of anesthesia and surgery, amount of blood loss, pain upon PACU arrival, use of paracetamol and parecoxib in PACU were found to be factors influencing amount of opioid consumption in PACU. ABO blood group was not associated with early postoperative opioid requirement. CONCLUSIONS: A significant number of factors are related to amount of opioid requirement in PACU. Some factors can be adjusted to provide better pain relief in early postoperative period. However, ABO blood group is not identified to be a predictive factor for early postoperative opioid consumption in PACU.

The effectiveness of regional anaesthesia before and after the introduction of a dedicated regional anaesthesia service incorporating a block room.

Dedicated regional anaesthesia services incorporating block rooms and/or block teams may facilitate theatre efficiency and improve training in regional anaesthesia. Currently, it is unknown if a dedicated regional anaesthesia service improves the effectiveness of regional anaesthesia. In November 2013, the Royal Brisbane and Women's Hospital established a dedicated regional anaesthesia service comprising a block team and a block room. Pre-intervention (conventional model of care) registry data was retrospectively compared with post-intervention (dedicated regional anaesthesia service) audit data, with regard to pain and opioid requirement in the post-anaesthesia care unit (PACU). The primary outcome was inadequate analgesia, defined as a numerical rating scale (NRS; 0, no pain; 10, worst pain imaginable) for pain >5 in the PACU. Pre- and post-intervention, 43.7% and 27.7% of patients respectively reported a NRS >5 (P <0.001). A difference in the type of blocks and surgery performed may have accounted for the improved outcome seen post-intervention. After adjustment for American Society of Anesthesiologists physical status, block type and surgery type, the odds ratio of having inadequate analgesia (NRS >5) was 0.54 (95% confidence interval 0.39 to 0.76) for post-intervention compared to pre-intervention. Secondary outcomes examined pre- and post-intervention were the absence of pain (39.3% and 55.1% of patients, respectively, P <0.001), systemic opioid analgesia requirement (48.6% and 30.5% of patients respectively, P <0.001) and median maximum NRS (4 [interquartile range (IQR) 0 to 8] and 0 [IQR 0 to 6] respectively, P <0.001). A dedicated regional anaesthesia service was associated with improved effectiveness of regional anaesthesia.

The Relation Between Patients' NRS Pain Scores and Their Desire for Additional Opioids after Surgery.

BACKGROUND: Postoperative pain is commonly assessed through a numerical rating scale (NRS), an 11-point scale where 0 indicates no pain and 10 indicates the worst imaginable pain. Guidelines advise the administration of analgesics at NRS pain scores above 3 or 4. In clinical practice, not all patients with pain scores above the treatment threshold are willing to accept additional analgesic treatment, especially when opioids are offered. The objective of this study is to measure the relation between patients' NRS pain scores and their desire for additional opioids. METHODS: This cross-sectional study examined 1,084 patients in an academic hospital the day after surgery between January 2010 and June 2010. The day after surgery, patients were asked to score their pain and desire for opioids. Sensitivity, specificity, positive predictive value, and negative predictive value of the desire for opioids and the different NRS thresholds were calculated. RESULTS: Only when patients scored an 8 or higher on the NRS did the majority express a need for opioids. Many patients did not desire opioids, because they considered their pain tolerable, even at an NRS score above 4. CONCLUSIONS: With the current guidelines (ie, using pain scores above 3 or 4 for prescribing opioids), many patients could be overtreated. Therefore, scores generated by the NRS should be interpreted individually.