Pain sensitivity and pain scoring in patients with morbid obesity

The Effect of Depth of Anesthesia on Postoperative Pain in Laparoscopic Sleeve Gastrectomy: A Randomized Controlled Trial

BACKGROUND

Patients with obesity are more sensitive to pain and more likely to have acute postoperative pain (APP). Studies have shown that the depth of anesthesia may affect the incidence of APP. The purpose of the study was to look into the connection between APP and depth of anesthesia in patients with obesity undergoing laparoscopic sleeve gastrectomy.

METHODS

This is a prospective, double-blinded randomized clinical trial, 90 patients undergoing laparoscopic sleeve gastrectomy were randomly divided into two groups: the light anesthesia group (Bispectral Index of 50, BIS 50) and the deep anesthesia group (BIS 35). The degree of pain was evaluated by the visual analogue scale (VAS) at 0, 12, 24, 48, and 72 h after surgery. The use of analgesics, grade of postoperative nausea and vomiting (PONV), and the Quality of Recovery-15 (QoR-15) score were recorded.

RESULTS

The VAS scores at rest or coughing at 0, 12, and 24 h after surgery in the BIS 35 group were lower than those in the BIS 50 group (P < 0.05). Fewer patients in the deep anesthesia group needed analgesia during the recovery period, and patient satisfaction was higher on the 3rd day after surgery (P < 0.015, P < 0.032, respectively).

CONCLUSIONS

For patients with obesity, maintaining a deeper depth of anesthesia during surgery is beneficial to reduce APP causes less need for additional analgesic drugs, and improves patient satisfaction.

Patients' strategies for numeric pain assessment: a qualitative interview study of individuals with hypermobile Ehlers-Danlos Syndrome

PURPOSE

Chronic pain is a common feature of hypermobile Ehlers-Danlos Syndrome (hEDS), yet how patients assess and communicate their pain remains poorly understood. The objective of the present study was to explore the use of numeric pain assessment in individuals with hEDS, from a patient-centered perspective.

MATERIALS AND METHODS

Our analysis is based on in-depth qualitative interviews. The interviews were conducted over the phone. Our participants were patients living with hEDS (N = 35). Interviews were recorded, transcribed, and analyzed to identify factors related to their use of these pain assessment instruments.

RESULTS

Three primary themes emerged from these data, namely, (1) confusion around the quantification of multidimensional pain, (2) the subjectivity of pain experience, and (3) a strategic use of assessments for practical purposes beyond the accurate representation of pain.

These results demonstrate the need for caution in relying exclusively on numeric pain assessment instruments. We conclude with a brief proposal for a clinical communication strategy that may help to address the limitations of numeric pain assessment that were identified in our interviews.

Individual Factors Modifying Postoperative Pain Management in Elective Total Hip and Total Knee Replacement Surgery

Total hip and knee replacements are the most common orthopedic procedures performed due to osteoarthritis. Pain is an intrinsic symptom accompanying osteoarthritis, persisting long before surgery, and continuing during the preoperative and postoperative periods. Appropriate pain management after surgery determines the comfort, duration, and cost of hospitalization, as well as the effectiveness of postoperative rehabilitation. Individual differences in pain perception and tolerance in orthopedic patients remain an important research topic. Therefore, the aim of this study was to investigate the predictors of analgesic requirements (morphine, acetaminophen, and ketoprofen), including individual pain threshold and tolerance, body mass index (BMI), diabetes, and beliefs about pain control in patients undergoing elective hip or knee arthroplasty using a multilevel regression model (N = 147, 85 women, 62 men, 107 after hip replacement, and 40 after knee replacement). Results: Higher pain tolerance was associated with a lower dose of morphine per kg after surgery. Patients undergoing hip surgery received a lower dose of ketoprofen than patients undergoing knee surgery. The more the patient believed in personal pain control, the stronger the negative relationship between pain tolerance and morphine requirement. The lowest doses were given to patients with the highest pain tolerance and the greatest belief in personal control. Factors such as belief in pain control and pain tolerance should be considered in comprehensive postoperative pain management in orthopedic patients to reduce opioid doses and, thus, side effects.

The effect of body mass index on thoracic paravertebral block analgesia after video-assisted thoracoscopic surgery; a prospective interventional study

BACKGROUND

To investigate the effects of body mass index (BMI) on intensity postoperative pain in patients who underwent thoracic paravertebral block (TPVB) for postoperative analgesia after video-assissted thoracoscopic surgery (VATS).

METHODS

Patients aged 18-80 years, ASA I-III, and BMI 18-40 kg/m2 who underwent elective VATS were included in the study. The patients were divided into 3 groups according to their BMI levels. TPVB was performed under ultrasound-guidance at the fifth thoracic vertebrae, and 30 ml of 0.25% bupivacaine was injected. The patient-controlled analgesia (PCA) was performed by using morphine and multimodal analgesia was performed. As a rescue analgesic agent, 0.5 mg/kg tramadol was given to patients intravenously when a score of visual analog scale (VAS) at rest was ≥ 4. The primary outcome was determined as VAS scores at rest and cough. Secondary outcomes were determined as postoperative morphine consumption, additional analgesic requirement, and side effects.

RESULTS

The post-hoc test revealed that the VAS resting scores at the 4th hour (p: 0.007), 12th hour (p: 0.014), and 48th hour (p: 0.002) were statistically significantly lower in Group I compared to Group II. Additionally, VAS resting scores were also statistically significantly lower in Group I compared to Group III at all time points (p < 0.05). Similarly, the post-hoc test indicated that the VAS coughing scores at the 4th hour (p: 0.023), 12th hour (p: 0.011), and 48th hour (p: 0.019) were statistically significantly lower in Group I compared to Group II. Moreover, VAS coughing scores were statistically significantly lower in Group I compared to Group III at all time points (p < 0.001). Furthermore, there were statistically significant differences in terms of additional analgesic use between the groups (p: 0.001). Additionally, there was a statistically significant difference in terms of morphine consumption via PCA and morphine milligram equivalent consumption between the groups (p < 0.001).

CONCLUSIONS

Higher postoperative VAS scores with TPVB applied in obese patients and the consequent increase in additional analgesics and complications require more specific postoperative management in this patient group.

Opioid Analgesics after Bariatric Surgery: A Scoping Review to Evaluate Physiological Risk Factors for Opioid-Related Harm

The persisting use of opioids following bariatric surgery has emerged as a prevalent complication, heightening the probability of opioid-related harm (ORM), such as opioid-related fatalities and prescription opioid use disorder (OUD). A comprehensive review of PubMed literature from 1990 to 2023 was conducted to pinpoint physiological influences on postoperative ORM. As a result, we found that patients undertaking bariatric operations often exhibit an inherently higher risk for substance use disorders, likely attributable to genetic predisposition and related neurobiological changes that engender obesity and addiction-like tendencies. Furthermore, chronic pain is a common post-bariatric surgery complaint, and the surgical type impacts opioid needs, with increased long-term opioid use after surgeries. Additionally, the subjective nature of pain perception in patients with obesity can distort pain reporting and the corresponding opioid prescription both before and after surgery. Furthermore, the postoperative alterations to the gastrointestinal structure can affect the microbiome and opioid absorption rates, resulting in fluctuating systemic exposure to orally ingested opioids. The prospect of ORM development post-bariatric surgery appears amplified due to a preexisting susceptibility to addictive habits, surgically induced pain, modified gut-brain interaction and pain management and the changed pharmacokinetics post-surgery. Further research is warranted to clarify these potential risk variables for ORM, specifically OUD, in the bariatric population.

Neuroendocrine and neuroimmune mechanisms underlying comorbidity of pain and obesity

Pain and obesity, as well as their associated impairments, are major health concerns. Understanding the relationship between the two is the focus of a growing body of research. However, early researches attribute increased mechanical stress from excessive weight as the main factor of obesity-related pain, which not only over-simplify the association, but also fail to explain some controversial outcomes arising from clinical investigations. This review focuses on neuroendocrine and neuroimmune modulators importantly involved in both pain and obesity, analyzing nociceptive and anti-nociceptive mechanisms based on neuroendocrine pathways including galanin, ghrelin, leptin and their interactions with other neuropeptides and hormone systems which have been reported to play roles in pain and obesity. Mechanisms of immune activities and metabolic alterations are also discussed, due to their intense interactions with neuroendocrine system and crucial roles in the development and maintenance of inflammatory and neuropathic pain. These findings have implications for health given rising rates of obesity and pain-related diagnoses, by providing novel weight-control and analgesic therapies targeted on specific pathways.

Respiratory Effects of Biased Ligand Oliceridine in Older Volunteers: A Pharmacokinetic-Pharmacodynamic Comparison with Morphine

BACKGROUND

Oliceridine is a G protein-biased µ-opioid, a drug class that is associated with less respiratory depression than nonbiased opioids, such as morphine. The authors quantified the respiratory effects of oliceridine and morphine in elderly volunteers. The authors hypothesized that these opioids differ in their pharmacodynamic behavior, measured as effect on ventilation at an extrapolated end-tidal Pco2 at 55 mmHg, V̇E55.

METHODS

This four-arm double-blind, randomized, crossover study examined the respiratory effects of intravenous 0.5 or 2 mg oliceridine and 2 or 8 mg morphine in 18 healthy male and female volunteers, aged 55 to 89 yr, on four separate occasions. Participants' CYP2D6 genotypes were determined, hypercapnic ventilatory responses were obtained, and arterial blood samples were collected before and for 6 h after treatment. A population pharmacokinetic-pharmacodynamic analysis was performed on V̇E55, the primary endpoint; values reported are median ± standard error of the estimate.

RESULTS

Oliceridine at low dose was devoid of significant respiratory effects. High-dose oliceridine and both morphine doses caused a rapid onset of respiratory depression with peak effects occurring at 0.5 to 1 h after opioid dosing. After peak effect, compared with morphine, respiratory depression induced by oliceridine returned faster to baseline. The effect-site concentrations causing a 50% depression of V̇E55 were 29.9 ± 3.5 ng/ml (oliceridine) and 21.5 ± 4.6 ng/ml (morphine), the blood effect-site equilibration half-lives differed by a factor of 5: oliceridine 44.3 ± 6.1 min and morphine 214 ± 27 min. Three poor CYP2D6 oliceridine metabolizers exhibited a significant difference in oliceridine clearance by about 50%, causing higher oliceridine plasma concentrations after both low- and high-dose oliceridine, compared with the other participants.

CONCLUSIONS

Oliceridine and morphine differ in their respiratory pharmacodynamics with a more rapid onset and offset of respiratory depression for oliceridine and a smaller magnitude of respiratory depression over time.

EDITOR’S PERSPECTIVE

Skin-to-Renal Pelvis Distance Predicts Costovertebral Angle Tenderness in Adult Patients with Acute Focal Bacterial Nephritis

OBJECTIVES

The aim of this study was to examine whether the distance between the skin and the renal pelvis affects the detection of costovertebral angle (CVA) tenderness in patients with acute focal bacterial nephritis (AFBN).

METHODS

We retrospectively reviewed the charts of our patients between April 2013 and June 2019 who were diagnosed as having AFBN. Diagnosis was based on ultrasound or computed tomography with contrast, revealing at least one wedge-shaped area of decreased vascularity and confirmation of fever not attributable to another condition.

RESULTS

We extracted 23 cases, all Japanese (mean age 60.0 years old [range 45-81 years], 7 males, 16 females). CVA tenderness was present in 8 of these 23 patients. Receiver operating characteristic curves were drawn to evaluate the ability to differentiate skin-to-renal pelvis distance (SPD), body mass index, and age. Only SPD was a useful predictor of CVA tenderness, and 66 mm was determined as the optimal cutoff point (area under the receiver operating characteristic curve 0.858, 95% confidence interval 0.70-1.00). Logistic regression analysis was performed with CVA tenderness as a dependent variable, and SPD, body mass index, and age as explanatory variables. SPD was an independent predictive variable of CVA tenderness (P = 0.038, odds ratio 0.76, 95% confidence interval 0.590-0.986).

CONCLUSIONS

CVA tenderness showed low yield in the diagnosis of AFBN in patients with longer SPD. Its use for diagnosis in obese patients may therefore be limited.

Maternal High-Energy Diet during Pregnancy and Lactation Impairs Neurogenesis and Alters the Behavior of Adult Offspring in a Phenotype-Dependent Manner

Obesity is one of the biggest and most costly health challenges the modern world encounters. Substantial evidence suggests that the risk of metabolic syndrome or obesity formation may be affected at a very early stage of development, in particular through fetal and/or neonatal overfeeding. Outcomes from epidemiological studies indicate that maternal nutrition during pregnancy and lactation has a profound impact on adult neurogenesis in the offspring. In the present study, an intergenerational dietary model employing overfeeding of experimental mice during prenatal and early postnatal development was applied to acquire mice with various body conditions. We investigated the impact of the maternal high-energy diet during pregnancy and lactation on adult neurogenesis in the olfactory neurogenic region involving the subventricular zone (SVZ) and the rostral migratory stream (RMS) and some behavioral tasks including memory, anxiety and nociception. Our findings show that a maternal high-energy diet administered during pregnancy and lactation modifies proliferation and differentiation, and induced degeneration of cells in the SVZ/RMS of offspring, but only in mice where extreme phenotype, such as significant overweight/adiposity or obesity is manifested. Thereafter, a maternal high-energy diet enhances anxiety-related behavior in offspring regardless of its body condition and impairs learning and memory in offspring with an extreme phenotype.

Obesity by High-Fat Diet Increases Pain Sensitivity by Reprogramming Branched-Chain Amino Acid Catabolism in Dorsal Root Ganglia

Obesity is a significant health concern as a result of poor-quality diet, for example, high-fat diet (HFD). Although multiple biological and molecular changes have been identified to contribute to HFD-induced pain susceptibility, the mechanisms are not fully understood. Here, we show that mice under 8 weeks of HFD were sensitive to mechanical and thermal stimuli, which was coupled with an accumulation of branched-chain amino acids (BCAAs) in lumbar dorsal root ganglia (DRG) due to local BCAA catabolism deficiency. This HFD-induced hyperalgesic phenotype could be exacerbated by supply of excessive BCAAs or mitigated by promotion of BCAA catabolism via BT2 treatment. In addition, our results suggested that HFD-related pain hypersensitivity was associated with a pro-inflammatory status in DRG, which could be regulated by BCAA abundance. Therefore, our study demonstrates that defective BCAA catabolism in DRG facilitates HFD-induced pain hypersensitivity by triggering inflammation. These findings not only reveal metabolic underpinnings for the pathogenesis of HFD-related hyperalgesia but also offer potential targets for developing diet-based therapy of chronic pain.

Pain-Related Anxiety among Adults with Obesity and Chronic Pain: Relations with Pain, Opioid Misuse, and Mental Health

Obesity affect a significant proportion of the population in the United States, and is associated with numerous health consequences including anxiety, depression, and chronic pain. Additionally, pain among adults with obesity has been associated with greater mental health problems and substance use problems. Yet little work has examined psychological vulnerability factors associated with these relations, and pain-related anxiety may be one candidate psychological correlate of these relations. Therefore, the current study examined the association of pain-related anxiety with pain intensity, disability, opioid misuse, anxiety, and depression among 164 adults (81.7% female, M_age = 40.13 years, SD = 10.85) with obesity (M_BMI= 37.21, SD = 6.70) and chronic pain. Results suggested that pain-related anxiety was significantly associated with all outcomes, and these results suggest that pain-related anxiety may play an important role in physical health, mental health, and substance use outcomes among adults with obesity and chronic pain.

Effect of early skin-to-skin contact after vaginal delivery on pain during perineal wound suturing: A randomized controlled trial

AIM

To evaluate whether early skin-to-skin contact at the end of the second stage of labor could relieve perineal wound suture pain.

METHODS

From March 2020 to November 2020, a total of 241 parturients with full-term single fetuses delivered through the vagina and who underwent episiotomy suture (n = 120) or perineal laceration repair (n = 121) in our hospital were included in the study. Parturients were categorized according to whether they received episiotomy suture or perineal laceration repair. They were randomized into an early skin contact group and a traditional neonatal care group. The primary outcome was pain, which was quantified by the Numerical Rating Scale, Visual Analog Scale, Verbal Rating Scale, Faces Pain Scale-Revised. The secondary outcomes were healing of the perineal wound, the maternal cooperation rate and operation time. The confounding factors of severe pain were analyzed.

RESULTS

Early skin-to-skin contact alleviated the pain of perineal laceration repair and episiotomy suture, shortened the operation time of episiotomy suture and improved the cooperation rate of parturients receiving suture. It had no effect on perineal wound healing, operation time, or the cooperation rate of perineal laceration repair. In addition to the operation and early skin contact, the occurrence of high-grade pain was also associated with prepregnancy body mass index, group B streptococcus (GBS) positive, and academic degree.

CONCLUSION

Early skin-to-skin contact at the end of the second stage of labor can alleviate pain and improve the delivery experience of vaginal delivery.

Pain sensitivity does not differ between obese and healthy weight individuals

Introduction

There is emerging evidence suggesting a relationship between obesity and chronic pain.

Objectives

The aim of this study was to determine whether pain-free obese individuals display altered pain responses to acute noxious stimuli, thus raising the possibility of greater pain sensitivity and potential susceptibility for chronic pain development.

Methods

Psychophysical and anthropometric data were collected from 38 individuals with an obese body mass index (BMI) classification (BMI ≥ 30) and 41 age/sex-matched individuals of a healthy BMI (BMI < 24.9). Because BMI may be an inaccurate index of obesity, additional anthropometric parameters of central adiposity and percent body fat were examined. Pain responses to suprathreshold noxious heat and cold stimuli were examined. Subjects provided pain intensity and unpleasantness ratings to noxious heat (49°C) applied at varying durations and locations (ventral forearm/lower leg). Cold pain ratings, thresholds, and tolerances were obtained after immersion of the hand in a cold-water bath (0-2°C). Between-group differences in pain responses, as well as relationships between pain responses and obesity parameters, were examined. Importantly, confounds that may influence pain such as anxiety, depression, impulsivity, sleepiness, and quality of life were assessed.

Results

No between-group differences in pain sensitivity to noxious heat and cold stimuli were found. No relationships were found between central adiposity or body fat (percentage or distribution) and pain responses to noxious heat or cold stimuli.

Conclusions

Obesity has minimal influence on pain sensitivity. Accordingly, it is unlikely that obesity alone increases susceptibility for chronic pain development through amplification of nociceptive processes.

Relation Between Body Mass Index and Dry Eye Disease: The Japan Public Health Center-Based Prospective Study for the Next Generation

OBJECTIVE

To investigate the relation between body mass index (BMI) and dry eye disease (DED).

METHODS

We conducted a cross-sectional questionnaire-based survey in 85,264 Japanese men and women aged 40 to 74 years who participated in the Japan Public Health Center-based Prospective Study for the Next Generation (JPHC-NEXT Study). Dry eye disease was defined as the presence of severe symptoms or clinical diagnosis. A multivariable logistic regression model was used to estimate the odds ratios (ORs) of DED associated with BMI and their two-sided 95% confidence intervals (CIs). We adjusted for age, cohort area, visual display terminal time, smoking status, alcohol intake, education status, income status, as well as history of hormone replacement therapy for women.

RESULTS

Prevalence of DED was 23.4% (n = 19,985; 6,289 men, 13,696 women). Higher BMI was correlated with a lower prevalence of DED in a dose-response fashion, with an adjusted OR of DED (95% CI) per 1 kg/m2 increment of BMI of 0.98 (95% CI: 0.97-0.99) for men and 0.97 (95% CI: 0.97-0.98) for women.

CONCLUSIONS

This large population-based study showed an inverse relationship between BMI and prevalence of DED in a Japanese population. Underestimation of DED is warned, especially for participants with high BMI.

Diet, body weight and pain susceptibility - A systematic review of preclinical studies

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Obesity has been associated with increased susceptibility to chronic pain.

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Dietary and genetic models of obesity have been used to study this association.

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Allodynia is a common finding but alterations in nociception were inconsistent across studies.

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In subacute/chronic models, nocifencive behaviors were increased and/or sustained.

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Reviewed studies are overall consonant with the clinical literature.

Obesity has been associated with increased chronic pain susceptibility but causes are unclear. In this review, we systematize and analyze pain outcomes in rodent models of obesity as these can be important tools for mechanistic studies. Studies were identified using MEDLINE/PubMed and Scopus databases using the following search query: (((pain) OR (nociception)) AND (obesity)) AND (rat OR (mouse) OR (rodent))). From each eligible record we extracted the following data: species, strain, sex, pain/obesity model and main behavioral readouts. Out of 695 records 33 were selected for inclusion. 27 studies assessed nociception/acute pain and 17 studies assessed subacute or chronic pain. Overall genetic and dietary models overlapped in pain-related outcomes. Most acute pain studies reported either decreased or unaltered responses to noxious painful stimuli. However, decreased thresholds to mechanical innocuous stimuli, i.e. allodynia, were frequently reported. In most studies using subacute and chronic pain models, namely of subcutaneous inflammation, arthritis and perineural inflammation, decreased thresholds and/or prolonged pain manifestations were reported in obesity models. Strain comparisons and longitudinal observations indicate that genetic factors and the time course of the pathology might account for some of the discrepancies observed across studies. Two studies reported increased pain in animals subjected to high fat diet in the absence of weight gain. Pain-related outcomes in experimental models and clinical obesity are aligned indicating that the rodent can be an useful tool to study the interplay between diet, obesity and pain. In both cases weight gain might represent only a minor contribution to abnormal pain manifestation.

Sonographic measures and sensory threshold of the normal sciatic nerve and hamstring muscles

PURPOSE

The sciatic nerve innervates the hamstring muscles. Occasionally, the sciatic nerve is injured along with a hamstring muscle. Detailed biomechanical and sensory thresholds of these structures are not well-characterized. Therefore, we designed a prospective study that explored high-resolution ultrasound (US) at multiple sites to evaluate properties of the sciatic nerve, including cross-sectional area (CSA) and shear-wave elastography (SWE). We also assessed SWE of each hamstring muscle at multiple sites. Mechanical algometry was obtained from the sciatic nerve and hamstring muscles to assess multi-site pressure pain threshold (PPT).

METHODS

Seventy-nine asymptomatic sciatic nerves and 147 hamstring muscles (25 males, 24 females) aged 18-50 years were evaluated. One chiropractic radiologist with 4.5 years of US experience performed the evaluations. Sciatic nerves were sampled along the posterior thigh at four sites obtaining CSA, SWE, and algometry. All three hamstring muscles were sampled at two sites utilizing SWE and algometry. Descriptive statistics, two-way ANOVA, and rater reliability were assessed for data analysis with p ≤ 0.05.

RESULTS

A significant decrease in sciatic CSA from proximal to distal was correlated with increasing BMI (p < 0.001). Intra-rater and inter-rater reliability for CSA was moderate and poor, respectively. Elastographic values significantly increased from proximal to distal with significant differences in gender and BMI (p = 0.002). Sciatic PPT significantly decreased between sites 1 and 2, 1 and 3, and 1 and 4. Significant correlation between gender and PPT was noted as well as BMI (p < 0.001). Hamstring muscle elastographic values significantly differed between biceps femoris and semitendinosus (p < 0.001) and biceps femoris and semimembranosus (p < 0.001). All three hamstring muscles demonstrated increased PPT in males compared to females (p < 0.001). In addition, PPT of the biceps femoris correlated with BMI (p = 0.02).

CONCLUSION

High-resolution US provided useful metrics of sciatic nerve size and biomechanical properties. PPT for the normal sciatic nerve and hamstring muscles was obtained for future clinical application.

Internal Herniation Incidence After RYGB and the Predictive Ability of a CT Scan as a Diagnostic Tool

PURPOSE

The clinical diagnosis of an internal herniation (IH) after a Roux-en-Y Gastric Bypass (RYGB) remains difficult; therefore, performing a CT scan is usually part of the diagnostic process. The goal of this study was to assess the incidence of IH in patients with open and closed MD (mesenteric defect) and to study if the ability to diagnose an IH with a CT scan is different between these groups.

MATERIALS AND METHODS

IH was defined as a visible intestine through the mesenteric defect underneath the jejunojejunostomy and/or in the Petersen's space. CT scan outcomes were compared with the clinical diagnosis of an IH. Until 31 June 2013, standard care was to leave mesenteric defects (MDs) open; after this date, they were always closed.

RESULTS

The incidence of IH in the primarily non-closed group was 3.9%, and in the primarily closed group, this was 1.3% (p = 0.001). In group A (non-closed MD and CT), the sensitivity of the CT scan was 80%, and specificity was 0%. In group C (closed MD and CT), the sensitivity was 64.7%, and specificity was 89.5%. In group B (non-closed, no CT), an IH was visible in 58.7% of the cases and not in 41.3%. In group D (only a re-laparoscopy), an IH was visible in 34.3% of the cases and not in 65.7%.

CONCLUSIONS

Using the CT scan in suspected IH is not useful in if the MDs were not closed. If the MDs were closed, then a CT scan is predictive for the diagnosis IH.

Quantitative sensory testing in feline osteoarthritic pain - a systematic review and meta-analysis

Quantitative sensory testing (QST) is a psychophysical test used to quantify somatosensory sensation under normal or pathological conditions including osteoarthritis (OA).

OBJECTIVE

This study aimed to conduct a systematic review and meta-analysis of studies using QST in healthy and osteoarthritic cats, registered at Systematic Review Research Facility (#26-06-2017).

DESIGN

Hierarchical models with random intercepts for each individual study extracted through the systematic review were fit to subject-level data; QST measures were contrasted between healthy and osteoarthritic cats. Four bibliographic databases were searched; quality and risk of bias assessment were performed using pre-established criteria.

RESULTS

Six articles were included; most were of high quality and low risk of bias. Punctate tactile threshold (n = 70) and mechanical temporal summation (n = 35) were eligible for analysis. Cats with OA have lower punctate tactile threshold [mean difference (95%HDI): -44 (-60; -26) grams] and facilitated temporal summation of pain [hazard ratio (95%HDI): 5.32 (2.19; 14) times] when compared with healthy cats. The effect of sex and body weight on sensory sensitivity remained inconclusive throughout all analyses. Due to the correlation between age and OA status, it remains difficult to assess the effect of OA on sensory sensitivity, independently of age.

CONCLUSIONS

Clear and transparent reporting using guidelines are warranted. Similar to people, centralized sensitization is a feature of OA in cats. Future studies should try to elucidate the age effect on feline OA. Research with natural OA in cats is promising with potential to benefit feline health and welfare, and improve translatability to clinical research.

Quantitative Sensory Testing in Adolescents with Co-occurring Chronic Pain and Obesity: A Pilot Study

Factors such as gender, ethnicity, and age affect pain processing in children and adolescents with chronic pain. Although obesity has been shown to affect pain processing in adults, almost nothing is known about pediatric populations. The aim of this pilot study was to explore whether obesity alters sensory processing in adolescents with chronic pain. Participants were recruited from a chronic pain clinic (Chronic Pain (CP), n = 12 normal weight; Chronic Pain + Obesity (CPO), n = 19 overweight/obesity) and from an obesity clinic (Obesity alone (O), n = 14). The quantitative sensory testing protocol included assessments of thermal and mechanical pain thresholds and perceptual sensitization at two sites with little adiposity. The heat pain threshold at the hand was significantly higher in the CPO group than in either the CP or O groups. Mechanical pain threshold (foot) was significantly higher in the CPO group than the CP group. No differences were found on tests of perceptual sensitization. Correlations between experimental pain and clinical pain parameters were found for the CPO group, but not for the CP group. This preliminary study provides important lessons learned for subsequent, larger-scale studies of sensory processing for youth with co-occurring chronic pain and obesity.

Obesity and Incident Prescription Opioid Use in the U.S., 2000-2015

INTRODUCTION

Prior studies have identified associations between obesity and numerous conditions that increase risks for chronic pain. However, the impact of obesity on prescription opioid use is not well known. This study investigates the association between obesity and incidence of long-term prescription opioid use.

METHODS

Fifteen panels of the Medical Expenditure Panel Survey from 2000 to 2015 were pooled to generate a sample of civilian non-institutionalized adults aged 30-84 years who were prescription opioid-naïve for approximately 9 months. Incident long-term prescription opioid use was defined as reporting use at 2 of 3 interviews during a 15-month follow-up. BMI was reported at baseline. Analyses were completed in 2019.

RESULTS

Among opioid-naïve adults (n=89,629), obesity was strongly associated with incident long-term prescription opioid use. The association increased at progressively higher BMI values, with 24% elevated odds (95% CI=7%, 44%) in adults with overweight (25-29.9 kg/m²) and 158% increased odds (95% CI=106%, 224%) among adults with Class III obesity (40-49.9 kg/m²). These associations grew with higher-dosage opioids. Of the reasons for opioid use, joint pain, back pain, injury, and muscle/nerve pain contributed the most to the excess use observed among adults with obesity. At the population level, 27.0% of incident long-term prescription opioid use (95% CI=19.0%, 34.8%) was attributable to adults having a BMI above normal weight (25-49.9 kg/m²).

CONCLUSIONS

These findings suggest that obesity has contributed to prescription opioid use in the U.S. Future investments in chronic pain reduction may benefit from increased integration with obesity prevention and treatment.

Modulation of Pain Sensitivity by Chronic Consumption of Highly Palatable Food Followed by Abstinence: Emerging Role of Fatty Acid Amide Hydrolase

There is a strong relationship between palatable diet and pain sensitivity, and the cannabinoid and opioid systems might play an important role in this correlation. The palatable diet used in many animal models of obesity is the cafeteria (CAF) diet, based on human food with high sugar, salt, and fat content. In this study, we investigated whether long-term exposure to a CAF diet could modify pain sensitivity and explored the role of the cannabinergic system in this modification. Male Sprague–Dawley rats were divided into two groups: one fed with standard chow only (CO) and the other with extended access (EA) to a CAF diet. Hot plate and tail flick tests were used to evaluate pain sensitivity. At the end of a 40-day CAF exposure, EA rats showed a significant increase in the pain threshold compared to CO rats, finding probably due to up-regulation of CB1 and mu-opioid receptors. Instead, during abstinence from palatable foods, EA animals showed a significant increase in pain sensibility, which was ameliorated by repeated treatment with a fatty acid amide hydrolase inhibitor, PF-3845 (10 mg/kg, intraperitoneally), every other day for 28 days. Ex vivo analysis of the brains of these rats clearly showed that this effect was mediated by mu-opioid receptors, which were up-regulated following repeated treatment of PF-3845. Our data add to the knowledge about changes in pain perception in obese subjects, revealing a key role of CB1 and mu-opioid receptors and their possible pharmacological crosstalk and reinforcing the need to consider this modulation in planning effective pain management for obese patients.

Association between higher BMI and postoperative pain and opioid consumption in pediatric inpatients - A retrospective cohort study

BACKGROUND

Childhood and adolescent obesity increased in recent decades, and caregivers face an increasing number of obese pediatric surgical patients. Some clinical and pharmacogenetic data suggest that obese patients have altered pain sensitivity and analgesic requirements.

OBJECTIVE

To test the primary hypothesis that increased BMI in pediatric patients is associated with increased pain during the initial 48 postoperative hours. Secondarily, we tested whether BMI is associated with increased opioid consumption during the same period.

DESIGN

Retrospective single-center cohort study.

SETTING

Pediatric surgical wards in a tertiary medical center.

PATIENTS

A total of 808 opioid naïve patients aged 8 to 18 years having elective non-cardiac surgery with hospital stay of at least 48 h in the Cleveland Clinic between 2010 and 2015.

INTERVENTIONS

None.

MEASUREMENTS

Using U.S. Centers for Disease Control definitions for childhood weight classifications, we retrospectively evaluated the association between body mass index (BMI) percentile and time-weighted average pain scores and opioid consumption. We used multivariable linear regression to test for an association with postoperative pain scores, and multivariable gamma regression to test for an association with postoperative opioid consumption (in mg morphine equivalents Kg^-1).

RESULTS

BMI was not associated with postoperative pain after general, orthopedic, or neuro-spinal surgeries. Pain increased by 0.07 [98.75% CI: (0.01, 0.13), P_adj < 0.05] points per 5 percentile increase in BMI after neuro-cranial surgery. Higher BMI was associated with a decrease in postoperative opioid consumption (mean change [95% CI] -2.12% [-3.12%, -1.10%] in morphine equivalents Kg^-1 per 5 percentile increase in BMI, P < 0.001).

CONCLUSION

We found no clinically important increase in pain scores or opioid consumption in association with higher BMI in patients 8 to 18 years of age recovering from elective non-cardiac surgery.

Effect of Trocar Site Bupivacaine Administration, Time of First Passage of Flatus, and Duration of the Surgery on Postoperative Pain After Sleeve Gastrectomy: a Case Control Study

INTRODUCTION

The effect of local anesthetic applications to trocar sites on postoperative pain control has been studied many times, and different results have been obtained. We planned a controlled study evaluating the effect of bupivacaine administration and other contributing factors on postoperative pain following sleeve gastrectomy.

MATERIAL AND METHODS

Patients who underwent laparoscopic sleeve gastrectomy were included in the study. Patients were randomized into two groups according to local application as either a local or non-local group. Also, the patients were grouped separately from local group allocation according to time to first passage of flatus (< 12 h, ≥ 12 h) and duration of surgery (> 50 min, ≤ 50 min). A visual analogue scale (VAS) was performed at 4, 8, 12, 24, and 48 h postoperatively. Opioid analgesics (pethidine HCl) were administered if the patient's VAS score was greater than 5. Demographic characteristics, such as age, gender, height, weight, body mass index (BMI), and operative time, were recorded. Demographic characteristics and VAS scores were compared between groups.

RESULTS

A total of 168 patients were included in the study. Of these, 84 patients were included in both of the local and non-local groups. The demographic characteristics between groups were similar. There was no significant difference between groups in terms of VAS scores (p > 0.05). In the analysis according to the time to first passage of flatus, the 48th-hour VAS scores were lower in the early flatus group (p = 0.036). According to the duration of surgery, first flatus was detected earlier, and VAS scores at the 8th and 12th hours were less in the short operation group (p < 0.001, p = 0.005, p = 0.031, respectively).

DISCUSSION

Although we did not show any effect of local administration of bupivacaine in LSG on pain, we concluded that other factors like duration of surgery and first flatus time have an impact on this issue.

Deleterious Effects of Higher Body Mass Index on Subjective and Objective Measures of Chemotherapy-Induced Peripheral Neuropathy in Cancer Survivors

CONTEXT

Recent, albeit, limited evidence suggests that body mass index (BMI) may be a modifiable risk factor to reduce the deleterious effects of chemotherapy-induced peripheral neuropathy (CIPN) in cancer survivors.

OBJECTIVES

To evaluate for differences in demographic, clinical, pain, sensation, and balance characteristics among three BMI groups. We hypothesized that as BMI increased, survivors would report higher pain intensity scores and have significant decrements in measures of sensation and balance.

METHODS

A total of 416 survivors with CIPN were evaluated using subjective and objective measures of CIPN. Survivors were divided into three BMI groups (i.e., normal weight, overweight, and obese). Differences among the BMI groups were evaluated using parametric and nonparametric statistics.

RESULTS

Of the 416 survivors, 45.4% were normal weight, 32.5% were overweight, and 22.1% were obese. Compared with the normal-weight group, survivors in the other two groups had lower functional status scores, a higher comorbidity burden, higher pain intensity scores, and higher interference scores. In addition, compared with the normal-weight group, survivors in the other two BMI groups had significantly worse balance scores.

CONCLUSION

Our findings support the hypothesis that as BMI increased, pain sensation and balance characteristics worsened. Our findings suggest that nutritional counseling as well as exercise and weight management programs in survivors with CIPN may improve these clinically important problems.

The effect of neuromuscular reversal agent on postoperative pain after laparoscopic gastric cancer surgery: Comparison between the neostigmine and sugammadex

Use of sugammadex for neuromuscular block reversal is associated with fewer postoperative complications than neostigmine; however, the effects on postoperative pain outcomes are largely unknown. In this retrospective study, we investigated the relationship between neuromuscular reversal agents and postoperative pain-related outcomes following laparoscopic gastric cancer surgery.We reviewed the electronic health records of patients who underwent laparoscopic gastric cancer surgery between January 2010 and June 2017. Patients were divided into a sugammadex group and a neostigmine group, according to the neuromuscular block reversal agent used. We compared the pain outcomes in the first 3 days postoperatively (POD 0-3), length of hospital stay, and postoperative complications (Clavien-Dindo grade ≥II).During the study period, 3056 patients received sugammadex (n = 901) or neostigmine (n = 2155) for neuromuscular reversal. After propensity score matching, 1478 patients (739 in each group) were included in regression analysis. In linear regression analysis, intravenous morphine equivalent consumption (mg) during POD 0 to 3 was higher in the sugammadex group than in the neostigmine group [coefficient 103.41, 95% confidence interval (CI): 77.45-129.37; P <.001]. However, hospital stay was shorter (coefficient: -0.60, 95% CI -1.12 to -0.08; P = .025) and postoperative complication rate was lower (odds ratio: 0.20, 95% CI 0.07-0.58; P = .003) in the sugammadex group.In this retrospective study, patients undergoing laparoscopic gastric cancer surgery who received sugammadex for neuromuscular block reversal exhibited greater postoperative analgesic requirements than those who received neostigmine but had a shorter hospital stay and a lower postoperative complication rate. A randomized and blinded study should be conducted in the future to confirm the findings of the present study.

Consequences of bariatric surgery on outcomes in rheumatic diseases

Obesity is associated with numerous comorbidities including some rheumatic conditions. Through adipose-derived inflammation, obesity has been shown to induce increased initiation, progression, and worse responses on outcomes of rheumatic diseases. Bariatric surgery is being increasingly used thanks to its positive effects on major comorbidities such as type 2 diabetes mellitus and hypertension. Consequently, surgically induced weight and adipose tissue losses might play a role in the course of rheumatic conditions. The present narrative literature review aims to provide rheumatologists with an update on both the positive and negative effects of bariatric surgery on the rheumatic outcomes reported in the literature. Current evidence seems to show improved outcomes in obese populations with rheumatic disorders after bariatric surgery. However, rigorous prospective controlled studies with long follow-up are needed. Bariatric procedures have deleterious effects on bone and are associated with an increased risk of fractures.

High fat diet sensitizes fibromyalgia-like pain behaviors in mice via tumor necrosis factor alpha

Fibromyalgia (FM) and obesity are closely related. However, little is known about how obesity contributes to FM. Importantly, adequate evidence has shown that tumor necrosis factor alpha (TNF-α) plays a critical role in obesity. Thus, we hypothesized that obesity-induced TNF-α release may potentiate FM-associated pain. To test this hypothesis, we investigated the role of TNF-α in the development of FM-like pain in a mouse model of acid saline injection-induced FM. Consistent with previous reports, we showed that repeated acid saline injections induced bilateral mechanical hyperalgesia, and this effect lasted for at least 4 days after acid saline injections. This phenomenon was associated with increased levels of TNF-α in plasma, muscles, and spinal cord. Furthermore, we found that 24 weeks of high fat diet treatment significantly potentiated acid saline-induced bilateral mechanical hyperalgesia. High fat diet-treated mice exhibited robustly increased levels of TNF-α in plasma, muscles, and spinal cord after acid saline injections compared with low fat diet-treated mice. Additionally, using immunofluorescence staining, we found that the number of TNF-α positive cells in dorsal root ganglion (DRG) was increased after acid saline injections, and high fat diet treatment further sensitized this increase. Finally, we reported that acid saline-induced FM-like pain behaviors were abolished in TNFRp55-/- mice, confirming the critical role of TNF-α in the development of FM-like pain. Taken together, our results suggested that high fat diet treatment may sensitize acid saline-induced FM-like pain via increasing TNF-α levels in plasma, muscles, and DRG.

Ketamine for pain

The efficacy of the N-methyl-D-aspartate receptor antagonist ketamine as an analgesic agent is still under debate, especially for indications such as chronic pain. To understand the efficacy of ketamine for relief of pain, we performed a literature search for relevant narrative and systematic reviews and meta-analyses. We retrieved 189 unique articles, of which 29 were deemed appropriate for use in this review. Ketamine treatment is most effective for relief of postoperative pain, causing reduced opioid consumption. In contrast, for most other indications (that is, acute pain in the emergency department, prevention of persistent postoperative pain, cancer pain, and chronic non-cancer pain), the efficacy of ketamine is limited. Ketamine's lack of analgesic effect was associated with an increase in side effects, including schizotypical effects.