Sevoflurane preconditioning in living liver donation is associated with better initial graft function after pediatric transplantation: a retrospective study.

INTRODUCTION: Initial allograft function determines the patient's immediate prognosis in pediatric liver transplantation. Ischemia-reperfusion injuries play a role in initial poor graft function (IPGF). In animal studies, preconditioning with inhaled anesthetic agents has demonstrated a protective effect on the liver. In humans, the few available studies are conflicting. This study assesses the association between the hypnotic agent used to maintain anesthesia during hepatectomy in living donors and the occurrence of IPGF after pediatric transplantation. METHODS: We conducted a single-center retrospective analysis of children who received a living donor liver transplant (LDLT) between 2010 and 2019. We analyzed the incidence of EAD according to the hypnotic agent used to maintain general anesthesia during donor hepatectomy. RESULTS: We included 183 pairs of patients (living donors-recipients). The anesthetics used in the donor were propofol (n = 85), sevoflurane (n = 69), or propofol with sevoflurane started 30 min before clamping (n = 29). Forty-two children (23%) developed IPGF. After multivariate logistic regression analysis, factors significantly associated with the occurrence of IPGF were the anesthesia maintenance agent used in the donor (p = 0.004), age of the donor (p = 0.03), duration of transplant surgery (p = 0.009), preoperative receiver neutrophil to lymphocyte ratio (p = 0.02), and albumin (p = 0.05). CONCLUSION: Significantly fewer children who received a graft from a donor in whom only sevoflurane was used to maintain anesthesia developed IPGF. Although additional research is needed, this preconditioning strategy may provide an option to prevent IPGF after living liver donation.

Cancer Pain Management: A Narrative Review of Current Concepts, Strategies, and Techniques.

Pain is frequently reported during cancer disease, and it still remains poorly controlled in 40% of patients. Recent developments in oncology have helped to better control pain. Targeted treatments may cure cancer disease and significantly increase survival. Therefore, a novel population of patients (cancer survivors) has emerged, also enduring chronic pain (27.6% moderate to severe pain). The present review discusses the different options currently available to manage pain in (former) cancer patients in light of progress made in the last decade. Major progress in the field includes the recent development of a chronic cancer pain taxonomy now included in the International Classification of Diseases (ICD-11) and the update of the WHO analgesic ladder. Until recently, cancer pain management has mostly relied on pharmacotherapy, with opioids being considered as the mainstay. The opioids crisis has prompted the reassessment of opioids use in cancer patients and survivors. This review focuses on the current utilization of opioids, the neuropathic pain component often neglected, and the techniques and non-pharmacological strategies available which help to personalize patient treatment. Cancer pain management is now closer to the management of chronic non-cancer pain, i.e., "an integrative and supportive pain care" aiming to improve patient's quality of life.

Do lifestyle factors influence pain prognosis? A 1-year follow-up study.

Objective: The aim of this observational longitudinal study was to investigate the impact of lifestyle factors on the prognosis of patients with pain. Methods: This study was part of a large prospective longitudinal study conducted in general practice (GP). Participants completed questionnaires at baseline (T0) and one year later (T1). Outcomes analysed were the EQ-5D index, presence of pain and the ability to perform a light work for 1 hour without difficulty. Results: Among 377 individuals with pain at T0, 294 still reported pain at T1. This subgroup had a significantly higher BMI, more painful sites, higher pain intensity, more sleep problems, poorer general self-rated health (GSRH) and higher Örebro Musculoskeletal Pain Screening Questionnaire (ÖMPSQ) score at T0 than pain-free individuals at T1. There were no differences in age, sex, physical activity and smoking. In multivariable analyses, the number of painful sites, GSRH, sleep problems, pain duration, pain intensity and 2 short-form 10-item Örebro musculoskeletal pain questionnaire (SF-ÖMPSQ) items were independently associated with at least one outcome 1 year later. Only GSRH was strongly associated with all outcomes. The accuracy of GSRH at T0 to classify participants according to dichotomous outcomes was overall moderate (0.7 < AUC <0.8). Conclusions: Lifestyle factors appear to have little influence on the outcome of patients with pain in GP. Conversely, poorer GSRH - which probably integrates the subjects' perception of several factors - could be considered a negative prognostic factor in patients with pain.

The High Burden of Acute and Chronic Pain in General Practice in French-Speaking Belgium.

Background: Chronic pain prevalence is very high in the general population, much higher than can be managed by chronic pain centers. Therefore, most pain patients are cared for by first-line professionals. However, general practitioners often feel ill at ease with these patients, and only a few studies assess the burden of chronic pain in general practice. To better estimate the resources needed to support these professionals, a good knowledge of (sub)acute and chronic pain prevalence and prognosis in general practices is needed. Methods: We report cross-sectional data from a larger longitudinal study performed in French-speaking general practices in Belgium in November 2018. Fifth-year medical students performing a one-month internship collected data for every third patient they saw each day: demographic information, pain characteristics, lifestyle, general health perception and the short Örebro Musculoskeletal Pain Screening Questionnaire in the French language. Results: 3882 patients (participation rate 66%) accepted to take part in the study. 22 and 50% of these suffered from (sub)acute and chronic pain, respectively. Pain was more often the motive of the consultation for (sub)acute than for chronic pain patients. Pain intensity and functional impact were moderate, irrespective of pain duration. 70% of (sub)acute and 31% of chronic pain patients were at low risk of chronicity. Conclusion: In our sample, chronic pain patients constituted 33-50% of patient contacts in general practice, indicating the high importance of providing adequate support to general practitioners and other first-line professionals, ie, by reinforcing collaboration with chronic pain centers.

Multichannel transcranial direct current stimulation over the left dorsolateral prefrontal cortex may modulate the induction of secondary hyperalgesia, a double-blinded cross-over study in healthy volunteers.

BACKGROUND: Central sensitization is thought to play a critical role in the development of chronic pain, and secondary mechanical hyperalgesia is considered one of its hall-mark features. Consequently, interventions capable of modulating its development could have important therapeutic value. Non-invasive neuromodulation of the left dorsolateral prefrontal cortex (DLPFC) has shown potential to reduce pain, both in healthy volunteers and in patients. Whether it can modulate the induction of central sensitization, however, is less well known. OBJECTIVE: To determine whether multifocal transcranial direct current stimulation (tDCS) targeting the left DLPFC affects the development of secondary mechanical hyperalgesia. METHODS: In this within-subjects, cross-over, double-blinded study, eighteen healthy volunteers participated in three experimental sessions. After 20 minutes of either anodal, cathodal, or sham multichannel tDCS over the left DLPFC, secondary mechanical hyperalgesia was induced using high-frequency electrical stimulation (HFS) of the volar forearm. We assessed intensity of perception to 128 mN mechanical pinprick stimuli at baseline and up to 240 minutes after HFS. We also mapped the area of mechanical hyperalgesia. RESULTS: HFS resulted in a robust and unilateral increase in the intensity of perception to mechanical pinprick stimuli at the HFS arm, which was not different between tDCS stimulation conditions. However, the area of hyperalgesia was reduced after anodal tDCS compared to sham. CONCLUSION: Anodal tDCS over the left DLPFC modestly modulates the size of the HFS-induced area of secondary mechanical hyperalgesia, suggesting that non-invasive neuromodulation targeting the left DLPFC may be a potential intervention to limit the development of central sensitization.

Can the French version of the short Örebro Musculoskeletal Pain Screening Questionnaire or its subsets predict the evolution of patients with acute, (sub) acute and chronic pain?

BACKGROUND: Prevention of chronic pain relies on accurate detection of at-risk patients. Screening tools have been validated mainly in (sub) acute spinal pain and the need of more generic tools is high. We assessed the validity of the French version of the short Örebro Musculoskeletal Pain Screening Questionnaire (ÖMPSQ) in patients with a large range of pain duration and localization. METHODS: First, we re-analyzed data from a 6-month longitudinal study of 73 patients with (sub) acute spinal pain consulting in secondary line settings. Secondly, we performed a new 12-month longitudinal study of 542 primary care patients with (sub) acute and chronic pain in different localizations (spinal, limbs, "non-musculoskeletal"). The area under the receiver operating characteristic curve and cutoff scores were computed and compared for different subpopulations and ÖMPSQ subscores. RESULTS: Data from patients suffering from (sub) acute and chronic spinal pain consulting in both primary and secondary care settings confirmed the validity of the short French ÖMPSQ version and its subsets. In the primary care cohort, the performance of the questionnaire and its psychosocial subscore was variable but at least "fair" in most populations ((sub) acute and chronic, spinal and limb pain). Cutoff scores showed quite large variability depending on the outcome and the subpopulation considered. CONCLUSIONS: These results confirm the usefulness of the short French ÖMPSQ for prediction of the evolution of (sub) acute and chronic patients with spinal and limb pain, whatever its duration. However, increasing population heterogeneity results in slightly worse predictive performance and largely variable cutoff scores. Consequently, it might be difficult to choose universal cutoff scores and other criteria, such as patients' values and the available resources for patient management, should be taken into account.

A Comparison of Genicular Nerve Blockade With Corticosteroids Using Either Classical Anatomical Targets vs Revised Targets for Pain and Function in Knee Osteoarthritis: A Double-Blind, Randomized Controlled Trial.

OBJECTIVE: Compare the effectiveness of genicular nerve blockade (GNB) using classical anatomical targets (CT) versus revised targets (RT) in patients suffering from chronic knee osteoarthritis pain. DESIGN: Double-blinded randomized controlled trial. SETTING: Pain medicine center of a teaching hospital. METHODS: We randomly assigned 55 patients with chronic knee osteoarthritis pain to receive a GNB (using a fluid mixture of 2 mL: lidocaine 1% + 20 mg triamcinolone) with either classical targets (CT-group, n = 28) or revised targets (RT-group, n = 27). Numeric rating pain scale (NRS), Oxford knee score (OKS), Western Ontario and McMaster Universities osteoarthritis index score (WOMAC), Quantitative analgesic questionnaire (QAQ) and global perceived effects were assessed at baseline, and at 1-hour, 24-hours, 1, 4, and 12 weeks post-intervention. RESULTS: The RT-group showed greater reduction in NRS mean score at 1-hour post-intervention (2.4 ± 2.1 vs 0.4 ± 0.9, 95% confidence interval (CI) [.0-.8] vs [1.6-3.2], P < .001). The proportion of patients achieving more than 50% knee pain reduction was higher in the RT-group at each follow up interval, yet these differences were statistically significant only at 1-hour post intervention (82.1% [95% CI = 63.1-93.9] vs 100% [95% CI = 97.2-100] P = .02). Both protocols resulted in significant pain reduction and joint function improvement up to 12 weeks post-intervention. CONCLUSIONS: The revised technique allowed more pain relief as well as greater proportion of successful responders at 1-hour post intervention. The large volume injected during therapeutic GNB could have compensated the lack of precision of the classical anatomical targets, mitigating differences in outcomes between both techniques.

Validation of a new protocol for ultrasound-guided genicular nerve radiofrequency ablation with accurate anatomical targets: cadaveric study.

INTRODUCTION: Ultrasound (US)-guided radiofrequency ablation (RFA) of genicular nerves (GNs) is increasingly performed to manage chronic knee pain. The anatomical foundations supporting the choice of original targets for US-guided GN-RFA have been thoroughly improved by recent anatomical studies. Therefore, this study aimed to provide a new protocol with revised anatomical targets for US-guided GN-RFA and to assess their accuracy in a cadaveric model. MATERIALS AND METHODS: Fourteen fresh-frozen cadaveric knees were used. After a pilot study with 4 knees, five consistent nerves were targeted in the other 10 knees with revised anatomical landmarks: superior medial genicular nerve (SMGN), superior lateral genicular nerve (SLGN), inferior medial genicular nerve (IMGN), recurrent fibular nerve (RFN) and the infrapatellar branch of the saphenous nerve (IPBSN). For each nerve, the lumen of radiofrequency (RF) cannula was prefilled with non-diffusible black paint, and then the cannula was inserted at the target site under US guidance. After US verification of correct placement, the stylet was introduced in the cannula to create a limited black mark on the tissues at the top of the active tip. Anatomical dissection was performed to assess for accuracy. RESULTS: The proportion of nerves directly found in contact with the black mark was 7/10, 8/10, 10/10 and 9/10 for the SMGN, SLGN, IMGN and RFN, respectively. The proportions of nerve captured by the theoretical largest monopolar RF lesions were 100% for the SMGN, IMGN and RFN, and IPBSN and 95% for SLGN. The mean distances from the center of the black mark to the targeted nerve were 2.1±2.2 mm, 1.0±1.4 mm, 0.75±1.1 mm and 2.4±4.5 mm for the SMGN, SLGN, IMGN and RFN, respectively. CONCLUSION: US-guided GN-RFA with revised anatomical targets resulted in accurate capture of the five targeted nerves. This protocol provides precise sensory denervation of a larger panel of nerves, targeting those whose constancy regarding anatomical location has been clearly demonstrated. It is expected to improve the clinical outcomes.

Robotic-Assisted Lobectomy Favors Early Lung Recovery versus Limited Thoracotomy.

BACKGROUND: Postoperative pulmonary recovery after lobectomy has showed early benefits for the video-assisted thoracoscopic surgery and sparing open techniques over nonsparing techniques. Robotic-assisted procedures offer benefits in term of clinical outcomes, but their advantages on pulmonary recovery and quality of life have not yet been distinctly prospectively studied. METHODS: Eighty-six patients undergoing lobectomy over a period of 29 months were prospectively studied for their pulmonary function recovery and pain score level during the in-hospital stay and at 1, 2, and 6 months. Quality of life was evaluated at 2 and 6 months. Forty-five patients were operated by posterolateral limited thoracotomy and 41 patients by robotic approach. The postoperative analgesia protocol differed for the two groups, being lighter for the robotic group. RESULTS: The pulmonary tests were not significantly different during the in-hospital stay. At 1 month, the forced expiratory volume in 1 second, forced vital capacity, vital capacity, and maximal expiratory pressure were significantly better for the robotic group (p = 0.05, 0.04, 0.05, and 0.02, respectively). There was no significant difference left at 2 and 6 months. Pain intensity was equivalent during the in-hospital stay but was significantly lower for the robotic group at 1 month (p = 0.02). At 2 and 6 months, pain and quality of life were comparable. CONCLUSION: Robotic technique can offer similar pulmonary and pain recovery during the in-hospital stay with a lighter analgesia protocol. It clearly favors the early term recovery compared with the open limited technique. The objective and subjective functional recovery becomes equivalent at 2 and 6 months.

Anatomical study of the descending genicular artery and implications for image-guided interventions for knee pain.

INTRODUCTION: The descending genicular artery (DGA) has recently been mentioned as accompanying some nerves in the medial aspect of the knee joint. This could be clinically relevant as the arteries could serve as landmarks for accurate nerve capture during ultrasound-guided nerve blockade or ablation. The aim of this cadaveric study was to investigate the anatomical distribution of the DGA, assess the nerves running alongside its branches, and discuss the implications for regional anesthesia and knee pain interventions. METHODS: We dissected the femoral artery (FA) all along its course to identify the origin of the DGA, from which we carefully dissected all branches, in 27 fresh-frozen human specimens. Simultaneously, we systematically dissected the nerves supplying the medial aspect of the knee from proximally to distally and identified those running alongside the branches of the DGA. The surrounding anatomical landmarks were identified and measurements were recorded. RESULTS: The DGA was found in all specimens, arising from the FA 130.5 ± 17.5 mm (mean ± SD) proximally to the knee joint line. Seven distribution patterns of the DGA were observed. We found three consistent branches from the DGA running alongside their corresponding nerves at the level of the medial aspect of the knee: the artery of the superior-medial genicular nerve, the artery of the infrapatellar branch of the saphenous nerve, and the saphenous branch of the DGA. CONCLUSION: The consistent arteries and surrounding landmarks found in this study could help to improve the capture of the targeted nerves during ultrasound-guided interventions.

Current versus revised anatomical targets for genicular nerve blockade and radiofrequency ablation: evidence from a cadaveric model.

INTRODUCTION: Recent studies have proposed revised anatomical targets to improve accuracy of genicular nerve (GN) radiofrequency ablation (RFA). This study aims to compare the accuracy of classical and revised techniques for fluoroscopic-guided GN-RFA in cadaveric models. MATERIALS AND METHODS: Fourteen knees from seven fresh frozen human cadavers were included in this study. For each cadaver, RF cannulas were placed to capture the GN according to the current targets in one knee, and the revised targets in the other knee, randomly. The stylet was removed from the cannula, plunged into non-diffusible black paint, and reintroduced entirely in the cannula, to create a limited black spot on the tissues at the top of the active tip. Anatomical dissection was performed, and the accuracy of both techniques was compared. RESULTS: The mean distance from the top of the active tip to the nerve was significantly lower with revised than current targets for the superior-medial GN (0.7 mm vs 17.8 mm, p=0.01) and the descending branch of the superior-lateral GN (3.7 mm vs 24.4 mm, p=0.02). In both superior-medial GN and superior-lateral GN, the accuracy rate was higher with revised than current targets: 100% vs 0% and 64% vs 35%, respectively. In addition, the accuracy of revised targets for the recurrent fibular nerve and the infrapatellar branch of saphenous nerve was 100%. CONCLUSION: This study demonstrates that the revised targets are more accurate than the current targets for GN-RFA.

Accuracy of fluoroscopic-guided genicular nerve blockade: a need for revisiting anatomical landmarks.

BACKGROUND AND OBJECTIVES: Genicular nerve blockade (GNB) and radiofrequency ablation (RFA) have recently emerged as treatment options for patients with chronic knee pain. However, an increasing number of anatomical studies and systematic reviews concluded that the anatomical basis for needle placement was unclear, incomplete and somewhat inaccurate. This study was designed to assess the accuracy of updated anatomical landmarks for fluoroscopy-guided blockade of the consistent genicular nerves in a cadaveric model. METHODS: Based on a comprehensive review of recent anatomical studies and prior dissection of 21 fresh cadaver knees, we defined bony landmarks with high likelihood of successful ablation of the five consistent genicular nerves (GN). We tested the accuracy of GNBs using the above-stated anatomical landmarks in 10 intact fresh cadaveric knees. Needle placement was guided by fluoroscopy and 0.5 mL of 0.1% methylene blue was injected at the site of each nerve. The knees were subsequently dissected to assess the accuracy of the injections. If the nerve was dyed with blue ink, the placement was considered accurate. RESULTS: The accuracy of our injections was 100% for the superior medial genicular nerve, inferior medial GN, infrapatellar branch of saphenous nerve and recurrent fibular nerve. The superior lateral GN was dyed in 90% of specimens. CONCLUSION: This study provides physicians with precise anatomical landmarks for the five consistent GN for fluoroscopic-guided GNB. Our revised technique, which targets more nerves with increased accuracy, could potentially lead to improved therapeutic benefits on chronic knee pain.

Pain management in living related adult donor hepatectomy: feasibility of an evidence-based protocol in 100 consecutive donors.

OBJECTIVE: Living donor hepatectomy (LDH) has important consequences in terms of acute and chronic pain. We proposed an anesthetic protocol based on the best currently available evidence. We report the results of this protocol's application. RESULTS: We performed a retrospective descriptive study of 100 consecutive donors undergoing LDH. The protocol included standardized information provided by the anesthetist, pharmacological anxiolysis and preventive analgesia. Specifically, pregabalin premedication (opioid-free) intravenous anesthesia (with clonidine, ketamine, magnesium sulphate and ketorolac) and epidural analgesia were proposed. Postoperative follow-up was conducted by the Postoperative Pain Service. This analysis included 100 patients (53 women, 47 men, median age 32.7 years old [28.4-37.3]), operated by xypho-umbilical laparotomy. All elements of our anesthetic protocol were applied in over 75% of patients, except for the preoperative consultation with a senior anesthesiologist (55%). The median number of applied item was 7 [interquartile range, IQR 5-7]. Median postoperative pain scores were, at rest and at mobilization respectively 3 [IQR 2-4] and 6 [IQR 4.5-7] on day 1; 2 [IQR 1-3] and 5 [IQR 3-6] on day 2; and 2 [IQR 0-3] and 4 [IQR 3-5] on day 3. In conclusion, LDH leads to severe acute pain. Despite the proposal of a multimodal evidence-based protocol, its applicancy was not uniform and the pain scores remained relatively high.

Prevention and Treatment of Chronic Postsurgical Pain: A Narrative Review.

Chronic postsurgical pain affects between 5 and 75% of patients, often with an adverse impact on quality of life. While the transition of acute to chronic pain is a complex process-involving multiple mechanisms at different levels-the current strategies for prevention have primarily been restricted to perioperative pharmacological interventions. In the present paper, we first present an up-to-date narrative literature review of these interventions. In the second section, we develop several ways by which we could overcome the limitations of the current approaches and enhance the outcome of our surgical patients, including the better identification of individual risk factors, tailoring treatment to individual patients, and improved acute and subacute pain evaluation and management. The third and final section covers the treatment of established CPSP. Given that evidence for the current therapeutic options is limited, we need high-quality trials studying multimodal interventions matched to pain characteristics.

DOSE AREA PRODUCT VALUES OF FLUOROSCOPICALLY GUIDED PAIN MANAGEMENT PROCEDURES: COMPARISON OF A BELGIAN TEACHING HOSPITAL WITH NATIONAL DIAGNOSTIC REFERENCE LEVELS.

In 2011, national diagnostic reference levels (DRLs) were proposed for pain management fluoroscopic procedures in Belgium. The primary goal of this work is to compare the dose area product values (DAP) recorded at the Saint-Luc University Hospital to these DRLs. From 2012 to 2015, 7664 interventional pain management procedures (4740 epidural, 2097 medial branch and 807 transforaminal infiltrations) were performed. Uni/multivariable analyses were done regarding the influence of different factors. The fluoroscopy duration and the DAP are lower to the DRLs (p < 0.001). From 7644 procedures' DAP, 1431 (18.7%) were higher than the DRLs: 1397 epidural (29.5%), 16 medial branch (0.8%) and 18 transforaminal infiltrations (2.2%) (p < 0.001 between procedures). The main factor that significantly modifies DAP, as duration, is the practitioner. Additionally, we obtained [IQR: 25-75] values for epidural [0.0174-0.055 mGy m2], medial branch block [0.0194-0.0472] and transforaminal infiltrations [0.0499-0.1067 mGy m2] (p < 0.05 vs. DRLs, respectively, 0.05, 0.25 and 0.3 mGy m2). Systematic use of contrast confirmation significantly increases DAP (p < 0.001). This retrospective analysis shows differences in DAP, mainly driven by the practitioner. This suggests the existence of modifiable factors. Programs aiming to determine these factors to reduce this DAP are justified.

Pain, Quality of Life, and Clinical Outcomes after Robotic Lobectomy.

Background To evaluate pulmonary function, pain, and quality of life at midterm after robotic lobectomy performed in a single institution. Methods Sixty-five consecutive patients underwent robotic thoracic surgery over 32 months using a complete four-arm portal technique. Sixty-one patients underwent lobectomies predominantly for stage I non-small cell lung cancer. Pulmonary function tests were repeated at midterm follow-up. Pain and quality of life were evaluated during the follow-up on a subgroup of 39 patients, excluding the learning period. Results At a mean of 7-month follow-up, there was no significant difference in preoperative and midterm postoperative pulmonary function. A total of 62.5% of the patients reported a variable intensity of discomfort or pain at the surgical site, with a mean pain intensity score of 2.1 ± 1.4. Mean pain interference score were weak (1.8 ± 1.9), with patients with moderate pain reporting significantly higher pain interference scores than those with mild pain (p = 0.0025). Only one patient suffered from neuropathic-like pain. Quality of life was globally favorable and related to the pain level, with a significant interference on the physical component. Conclusion Robotic lobectomy does not appear to have an impact on midterm pulmonary function. Persistent postoperative pain is mild, nonneuropathic-like, with weak interference on daily activities. Quality of life is satisfactory but related to the pain level.

Opioid-free anesthesia opioid side effects: Tolerance and hyperalgesia.

Opioids are the most potent drugs used to control severe pain. However, neuroadaptation prevents opioids' ability to provide long-term analgesia and produces opposite effects, i.e., enhancement of existent pain and facilitation of chronic pain development. Neuroadaptation to opioids use results in the development of two interrelated phenomena: tolerance and "opioid-induced hyperalgesia" (OIH). Tolerance, a pharmacologic concept, and OIH, a clinical syndrome, have been mostly observed under experimental conditions in animals and in human volunteers. In contrast, their occurrence and relevance in clinical practice remain debated. In perioperative setting, intraoperative administration of high doses of opioids increases postoperative opioid requirements and worsens pain scores (acute tolerance or perioperative OIH). Further, preoperative chronic opioid intake and postoperative long-term use of opioid analgesics beyond the normal healing period have a negative effect on surgical outcome. Conversely, observations of improved patient's recovery after opioid-sparing anesthesia techniques stand as an indirect evidence that perioperative opioid administration deserves caution. To date, perioperative OIH has rarely been objectively assessed by psychophysics tests in patients. A direct relationship between the presence of perioperative OIH and patient outcome is missing and certainly deserves further studies.