Quantification of Skeletal Muscle Perfusion in Peripheral Artery Disease Using 18F-Sodium Fluoride Positron Emission Tomography Imaging

BACKGROUND

Perfusion deficits contribute to symptom severity, morbidity, and death in peripheral artery disease (PAD); however, no standard method for quantifying absolute measures of skeletal muscle perfusion exists. This study sought to preclinically test and clinically translate a positron emission tomography (PET) imaging approach using an atherosclerosis-targeted radionuclide, fluorine-18-sodium fluoride (18F-NaF), to quantify absolute perfusion in PAD.

METHODS AND RESULTS

Eight Yorkshire pigs underwent unilateral femoral artery ligation and dynamic 18F-NaF PET/computed tomography imaging on the day of and 2 weeks after occlusion. Following 2-week imaging, calf muscles were harvested to quantify microvascular density. PET methodology was validated with microspheres in 4 additional pig studies and translated to patients with PAD (n=39) to quantify differences in calf perfusion across clinical symptoms/stages and perfusion responses in a case of revascularization. Associations between PET perfusion, ankle-brachial index, toe-brachial index, and toe pressure were assessed in relation to symptoms. 18F-NaF PET/computed tomography quantified significant deficits in calf perfusion in pigs following arterial occlusion and perfusion recovery 2 weeks after occlusion that coincided with increased muscle microvascular density. Additional studies confirmed that PET-derived perfusion measures agreed with microsphere-derived perfusion measures. Translation of imaging methods demonstrated significant decreases in calf perfusion with increasing severity of PAD and quantified perfusion responses to revascularization. Perfusion measures were also significantly associated with symptom severity, whereas traditional hemodynamic measures were not.

CONCLUSIONS

18F-NaF PET imaging quantifies perfusion deficits that correspond to clinical stages of PAD and represents a novel perfusion imaging strategy that could be partnered with atherosclerosis-targeted 18F-NaF PET imaging using a single radioisotope injection.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03622359.

Home-Based Pediatric Hospice and Palliative Care Provider Visits: Effects on Healthcare Utilization

OBJECTIVE

This hypothesis-generating study sought to assess the impact of home-based hospice and palliative care (HBHPC) provider home visits (HV) on healthcare use.

STUDY DESIGN

Retrospective review of individuals ages 1 month to 21 years receiving an in-person HBHPC provider (MD/DO or APN) HV through 2 HBHPC programs in the Midwest from January 1, 2013, through December 31, 2018. Descriptive statistics were calculated for healthcare use variables. Paired t test or Wilcoxon signed-rank test compared the changes in healthcare use the year before and year after initial provider HVs.

RESULTS

The cohort included 195 individuals (49% female), with diagnoses composed of 49% neurologic, 30% congenital chromosomal, 11% oncologic, 7% cardiac, and 3% other. After implementation of HBHPC services, these patients showed decreases in the median (IQR) number of intensive care unit days (before HV, 12 [IQR, 4-37]; after HV, 0 [IQR, 0-8]; P < .001); inpatient admissions (before HV, 1 [IQR, 1-3]; after HV, 1 [IQR, 0-2]; P = .005); and number of inpatient days (before HV, 5 [IQR, 1-19]; after HV, 2 [IQR, 0-8]; P = .009). There was an increase in clinically relevant phone calls to the HBHPC team (before HV, 1 [IQR, 0-4] vs after HV, 4 [IQR, 1-7]; P < .001) and calls to the HBHPC team before emergency department visits (before HV, 0 [IQR, 0-0] vs after HV, 1 [IQR, 1-2]; P < .001).

CONCLUSION

HBHPC provider HVs were associated with fewer inpatient admissions, hospital days, and intensive care unit days, and increased clinically relevant phone calls and phone calls before emergency department visit. These findings indicate that HBHPC HV may contribute to decreased inpatient use and increased use of the HBHPC team.

Preoperative gastric point-of-care ultrasound in nonelective surgical procedures in pediatric-aged patients

Background

Airway management for nonelective surgical procedures in the setting of trauma, pain, and opioid use can be complicated by the potential for aspiration due to delayed gastric emptying. Point-of-care ultrasound (POCUS) remains a useful tool for evaluating gastric content and volume in various clinical settings. The authors evaluated gastric volume and content in children scheduled for urgent and semi-urgent procedures to assess their aspiration risk.

Methods

After obtaining consent, gastric POCUS was performed in the preoperative holding area for pediatric patients scheduled for both elective and nonelective surgery. Qualitative and quantitative measurements of the gastric antrum were taken, and the risk of gastric aspiration was calculated. Additional data collected included patient demographics, the type of surgery, nil per os (NPO) status at the time of surgery, NPO status at the time of injury, and administration of opioids.

Results

The study cohort included 100 patients ranging in age from 3 to 17 years old (mean age 9.2 years). Out of these 100 patients, gastric scanning was successfully conducted in 98 patients. Sixteen of fifty-nine nonelective patients (27%) had received opioids for pain control prior to surgery. Among the 34 patients who had suffered an acute injury, 7 (21%) had been NPO for <8 hours at the time of the injury. Ninety-nine out of hundred patients had been NPO for at least 6 hours at the time of the gastric ultrasound. Based on our gastric ultrasound findings, all patients who were appropriately NPO had either Grade 0 or Grade 1 risk for aspiration, indicating a low risk of aspiration.

Conclusions

The preliminary data show that when patients presenting for nonelective surgery are appropriately NPO, they may have a low risk of aspiration. This information may help guide the choice of anesthetic induction technique, particularly when concerns exist about the safety of a rapid sequence induction. It allows for a more stable and controlled induction of anesthesia.

Application of behavioral economic strategies to enhance recruitment into a pediatric randomized clinical trial for postoperative pain relief: A randomized clinical trial

INTRODUCTION

A major challenge in conducting clinical trials is recruitment. Trial under-enrollment leads to underpowered studies. Behavioral economics offers strategies that may enhance trial recruitment. This study assessed the impact of behavioral economic strategies versus a standard biological approach to recruit children into a randomized clinical trial assessing a biofeedback-based virtual reality intervention for postoperative pain management. We hypothesized the behavioral economics-informed approach would increase enrollment into the future trial, intention to adhere to therapy, acceptability of the intervention, and perceived efficacy while decreasing perception of treatment burden and risk.

METHODS

This single-center, prospective, randomized trial recruited patients 12-18 years old undergoing surgery requiring postoperative admission and narcotic administration. Patient-parent dyads were randomized to watch a behavioral economics-informed (n = 64) or standard biological (n = 66) recruitment video about a study designed to assess impact of a virtual reality pain management intervention.

RESULTS

There was no difference in rates of intention to enroll in the study between groups (behavioral economics: 75%, control: 79%, p = 0.744) or in median response scores to questions regarding intention to adhere to therapy (4.0 [3.0, 4.0] vs. 4.0 [3.0, 4.0], p=0.084), acceptability of therapy (4.0 [3.0, 4.0] vs. 4.0 [3.0, 4.0], p = 0.376), perceptions of treatment burden (3.0 [3.0, 4.0] vs. 4.0 [3.0, 4.0], p=0.251), and efficacy (3.0 [3.0, 4.0] vs. 3.0 [3.0, 4.0], p = 0.914). Patients in the behavioral economics group were less likely to perceive risk associated with virtual reality versus the control group (behavioral economics: 2.0 [1.0, 2.0], control: 2.0 [2.0, 3.0], p = 0.023).

DISCUSSION

A behavioral economics-informed video did not increase patients' intentions to enroll into a clinical trial assessing the impact of virtual reality intervention for postoperative pain management.

CONCLUSION

Either approach would be sufficient for patient recruitment for this type of clinical trial since the overall intention to enroll rate was 77%.

Impact of opioid law on prescriptions and satisfaction of pediatric burn and orthopedic patients: An epidemiologic study

OBJECTIVES

The objective of this study was to determine the reduction in prescribed opioid pain dosage units to pediatric patients experiencing acute pain and to assess patient satisfaction with pain control 90-day post discharge following the 2017 Ohio opioid prescribing cap law.

METHODS

The retrospective chart review included 960 pediatric (age 0-18 years) burn injury and knee arthroscopy patients treated between August 1, 2015-August 31, 2019. Prospectively, legal guardians completed a survey for a convenience sample of 50 patients. Opioid medications (days and morphine milligram equivalents (MMEs)/kg) prescribed at discharge before and after the Ohio law implementation were collected. Guardians reported experience and satisfaction with their child's opioid prescription at 90-days post discharge.

RESULTS

From pre-law to post-law, there was a significant decrease (p<0.001) within the burn and knee cohorts in the median days (1.7 to 1.0 and 5.0 to 3.8, respectively) and median total MMEs prescribed (15.0 to 2.5 and 150.0 to 90.0, respectively). An interrupted time series analysis revealed a statistically significant decrease in MMEs/kg and days prescribed at discharge when the 2017 Ohio opioid prescription law went into effect, with an abrupt level change. Prospectively, more than half of participants were satisfied (72% burn and 68% knee) with their pain control and felt they received the right amount of medication (84% burn and 56% knee). Inpatient opioid use was not changed pre- and post-law.

CONCLUSIONS

Discharge opioids prescribed for pediatric burn and knee arthroscopy procedures has decreased from 2015-2019. Caregivers varied greatly in their satisfaction with pain control and the amount of opioid prescribed.

Efficacy of an expanded preoperative survey during perioperative care to identify illicit substance use in teenagers and adolescents

BACKGROUND

As illicit substance use can present several perioperative concerns, effective means to identify such practices are necessary to ensure patient safety. Identification of illicit substance use in pediatric patients may be problematic as screening may rely on parental reporting.

AIMS

The current study compares answers regarding use of illicit substances between a survey completed by the patient and the preoperative survey completed by parents or guardians.

METHODS

The study included patients presenting for surgery at Nationwide Children's Hospital, ranging in age from 12 to 21 years. After consent, patients completed a survey of six drop-down questions using an iPad. The six questions involved the patient's history of alcohol, tobacco, marijuana, vaping, and opioid use. The results were compared to the answers obtained from the parents during a preoperative phone call.

RESULTS

The study cohort included surveys from 250 patients with a median age of 16 years. Survey data showed a statistically higher reporting of substance use or abuse from the patient study survey in comparison to the routine parental preoperative survey. Alcohol report rates were highest with 69 (27.6%) patients reporting use compared to only 5 parental reports (2%). There was a similar discrepancy in reported rates of vaping use (40 patient reports, 16.0% vs. 11 parental reports, 4.4%) and illicit substance use including marijuana (52 patient reports, 20.8% vs. 11 parental reports, 4.4%). Reported rates of tobacco use were lowest among the survey responses with 12 patient reports (4.8%) and 5 parental reports (2.0%).

CONCLUSIONS

Identifying illicit substance and tobacco use via a phone survey of parents is inaccurate and does not allow for proper identification of use of these substances in patients ≤21 years of age presenting for surgery. An anonymous 2-min survey completed by the patient more correctly identifies these issues.

Deep learning of image-derived measures of body composition in pediatric, adolescent, and young adult lymphoma: association with late treatment effects

OBJECTIVES

The objective of this study was to translate a deep learning (DL) approach for semiautomated analysis of body composition (BC) measures from standard of care CT images to investigate the prognostic value of BC in pediatric, adolescent, and young adult (AYA) patients with lymphoma.

METHODS

This 10-year retrospective, single-site study of 110 pediatric and AYA patients with lymphoma involved manual segmentation of fat and muscle tissue from 260 CT imaging datasets obtained as part of routine imaging at initial staging and first therapeutic follow-up. A DL model was trained to perform semiautomated image segmentation of adipose and muscle tissue. The association between BC measures and the occurrence of 3-year late effects was evaluated using Cox proportional hazards regression analyses.

RESULTS

DL-guided measures of BC were in close agreement with those obtained by a human rater, as demonstrated by high Dice scores (≥ 0.95) and correlations (r > 0.99) for each tissue of interest. Cox proportional hazards regression analyses revealed that patients with elevated subcutaneous adipose tissue at baseline and first follow-up, along with patients who possessed lower volumes of skeletal muscle at first follow-up, have increased risk of late effects compared to their peers.

CONCLUSIONS

DL provides rapid and accurate quantification of image-derived measures of BC that are associated with risk for treatment-related late effects in pediatric and AYA patients with lymphoma. Image-based monitoring of BC measures may enhance future opportunities for personalized medicine for children with lymphoma by identifying patients at the highest risk for late effects of treatment.

KEY POINTS

• Deep learning-guided CT image analysis of body composition measures achieved high agreement level with manual image analysis. • Pediatric patients with more fat and less muscle during the course of cancer treatment were more likely to experience a serious adverse event compared to their clinical counterparts. • Deep learning of body composition may add value to routine CT imaging by offering real-time monitoring of pediatric, adolescent, and young adults at high risk for late effects of cancer treatment.

A ROTEM-guided algorithm aimed to reduce blood product utilization during neonatal and infant cardiac surgery

BACKGROUND

Neonates and infants undergoing cardiac surgery tend to receive high volumes of blood products. The use of rotational thromboelastometry (ROTEM^®) has been shown to reduce the administration of blood products in adults after cardiac surgery. We sought to develop a targeted administration of blood products based on ROTEM^® to reduce blood product utilization during and after neonatal and infant cardiac surgery.

METHODS

We conducted a retrospective review of data from a single center for neonates and infants undergoing congenital cardiac surgery using cardiopulmonary bypass (CPB) from September 2018-April 2019 (control group). Then, using a ROTEM^® algorithm, we collected data prospectively between April-November 2021 (ROTEM group). Data collected included age, weight, gender, procedure, STAT score, CPB time, aortic cross-clamp time, volume, and type of blood products administered in the operating room and cardiothoracic intensive care unit (CTICU). In addition, ROTEM^® data, coagulation profile in CTICU, chest tube output at 6 and 24 hours, use of factors concentrate, and thromboembolic complications were recorded.

RESULTS

The final cohort of patients included 28 patients in the control group and 40 patients in the ROTEM group. The cohort included neonates and infants undergoing the following procedures: arterial switch, aortic arch augmentation, Norwood procedure, and comprehensive stage II procedure. There were no differences in the demographics or procedure complexity between the two groups. Patients in the ROTEM^® group received fewer platelets (36 ± 12 vs. 49 ± 27 mL/kg, p 0.028) and cryoprecipitate (8 ± 3 vs. 15 ± 10 mL/kg, p 0.001) intraoperatively when compared to the control group.

CONCLUSION

The utilization of ROTEM^® may have contributed to a significant reduction in some blood product administration during cardiac surgery for infants and neonates. ROTEM^® data may play a role in reducing blood product administration in neonatal and infant cardiac surgery.

Prognostic Value of Fluorine-18-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Imaging for Predicting Venous Thromboembolism in Children With Lymphoma

BACKGROUND

Positron emission tomography (PET)/computed tomography (CT) imaging can detect changes in arterial inflammation, but has not been used to evaluate chemotherapy-induced venous inflammation or assess risk for venous thromboembolism (VTE) in pediatric oncology. Therefore, the purpose of this study was to evaluate the prognostic value of fluorine-18-fluorodeoxyglucose PET/CT imaging of venous inflammation for predicting VTE occurrence in the 12 months after lymphoma diagnosis in pediatric, adolescent, and young adult patients.

METHODS

Pediatric, adolescent, and young adult patients with lymphoma diagnoses (n=71) who underwent whole-body PET/CT imaging at initial staging of disease and first therapeutic follow-up were retrospectively evaluated for serial changes in lower extremity venous uptake of fluorine-18-fluorodeoxyglucose. PET/CT images were used to segment and quantify serial changes in fluorine-18-fluorodeoxyglucose uptake for veins of interest (ie, popliteal and femoral). Incidence of VTE was assessed for 12 months after lymphoma diagnosis.

RESULTS

PET/CT detected a significantly higher inflammatory response in the femoral (P=0.012) and popliteal (P=0.013) veins of patients who experienced a VTE event compared with those who remained VTE free in the 12 months after diagnosis. The area under the curve values for receiver operator characteristics analyses were 0.76 (femoral vein) and 0.77 (popliteal vein) based on incidence of VTE occurrence. Univariate analyses demonstrated that PET/CT-derived changes in femoral (P=0.008) and popliteal (P=0.002) vein inflammation were significantly associated with VTE-free survival at 12 months after diagnosis.

CONCLUSIONS

Fluorine-18-fluorodeoxyglucose PET/CT imaging detects treatment-induced venous toxicity that may provide insight into risk of VTE events in pediatric and adolescent and young adult patients with lymphoma.

Childhood obesity trends: Association with same-day hospital admission in a National Outpatient Surgical Population

BACKGROUND

Although the prevalence of obesity in the general population and its perioperative implications among children undergoing inpatient surgeries are well known, little is known about obesity prevalence among children scheduled for ambulatory surgery.

AIMS

Here, we report the trends of obesity and severe obesity among children who underwent ambulatory surgery across multiple centers in the United States and explore the association of obesity status with admission following elective ambulatory surgery.

MATERIALS AND METHODS

Using data from the American College of Surgeons National Surgical Quality Improvement Program-Pediatric (2012-2019), we selected children 2-18 years old who underwent outpatient surgical procedures under general anesthesia and had documented height, weight, and body mass index (BMI) data. We estimated the prevalence of overweight, obesity (class 1), and severe obesity (class 2 and class 3) patients and explored their association with same-day hospital admission, defined as hospital length of stay ≥1 day.

RESULTS

Data from 152 918 children (mean age: 9.7 ± 4.7 years) were analyzed. Of these, 16.4% (n = 25 007) were overweight, 13.8% (n = 21 085) were class 1 obese, 5.2% (n = 7879) were class 2 obese, and 3.0% (n = 4623) were class 3 obese. From 2012 to 2019, class 2 or 3 obesity prevalence increased by 26.7% and 32.5%, respectively. Overweight and obese children had relatively higher odds of same-day hospital admission compared to healthy weight children (overweight odds ratio [95% confidence interval]: 1.05 [1.02, 1.08]; class 1 obesity: 1.04 [1.00, 1.07]; class 2 obesity: 1.09 [1.02, 1.16]; class 3 obesity: 1.20 [1.11, 1.30]).

DISCUSION AND CONCLUSION

The burden of obesity continues to increase in children scheduled for ambulatory surgery. Children with class 2 and class 3 obesity have higher rates of same-day hospital admission following elective ambulatory surgery compared to healthy weight children, a factor that should be considered in scheduling these patients.

A Multimodal Approach to Quantify Chondrocyte Viability for Airway Tissue Engineering

OBJECTIVES/HYPOTHESIS

Partially decellularized tracheal scaffolds have emerged as a potential solution for long-segment tracheal defects. These grafts have exhibited regenerative capacity and the preservation of native mechanical properties resulting from the elimination of all highly immunogenic cell types while sparing weakly immunogenic cartilage. With partial decellularization, new considerations must be made about the viability of preserved chondrocytes. In this study, we propose a multimodal approach for quantifying chondrocyte viability for airway tissue engineering.

METHODS

Tracheal segments (5 mm) were harvested from C57BL/6 mice, and immediately stored in phosphate-buffered saline at -20°C (PBS-20) or biobanked via cryopreservation. Stored and control (fresh) tracheal grafts were implanted as syngeneic tracheal grafts (STG) for 3 months. STG was scanned with micro-computed tomography (μCT) in vivo. STG subjected to different conditions (fresh, PBS-20, or biobanked) were characterized with live/dead assay, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), and von Kossa staining.

RESULTS

Live/dead assay detected higher chondrocyte viability in biobanked conditions compared to PBS-20. TUNEL staining indicated that storage conditions did not alter the proportion of apoptotic cells. Biobanking exhibited a lower calcification area than PBS-20 in 3-month post-implanted grafts. Higher radiographic density (Hounsfield units) measured by μCT correlated with more calcification within the tracheal cartilage.

CONCLUSIONS

We propose a strategy to assess chondrocyte viability that integrates with vivo imaging and histologic techniques, leveraging their respective strengths and weaknesses. These techniques will support the rational design of partially decellularized tracheal scaffolds.

LEVEL OF EVIDENCE

N/A Laryngoscope, 133:512-520, 2023.

Vial-splitting and Repackaging into Aliquot-specific Syringes: A Cost-effective and Waste-decreasing Strategy for Sugammadex

Sugammadex is a medication that may have cost considerations with the potential for waste of unused product in pediatric patients due to the vial size and its single-use limitation. Therefore, exploring the potential of vial-splitting for perioperative use may be beneficial.

Methods

The study was a retrospective, quality improvement study using the electronic medical record to identify every sugammadex administration over the last five years in a tertiary care pediatric institution. We divided patients into groups depending on the dose of sugammadex administered. The cost of sugammadex was calculated under three scenarios: (1) only 200-mg vials available; (2) 100-mg aliquots available; and (3) 50-mg aliquots. We then calculated the total money spent per patient in the 3 scenarios.

Results

31,063 patients received sugammadex over the study period, of whom 23.6% received 151-200 mg. The greatest percentage of patients received ≤50 mg (32.9%). The average cost per patient was $113.58, $81.61, and $68.83 if 200 mg, 100 mg, and 50 mg doses were available, respectively. Over the last 5 years, $1,390,110.13 could have been saved by having 50 and 100 mg aliquots available.

Conclusions

Pediatric patients generally receive lower doses of sugammadex due to weight-based dosing, leading to increased waste and cost when using only 200-mg vials. Vial-splitting into smaller aliquots can significantly cut costs for healthcare centers and patients while decreasing waste.

The Roles of Vitreous Biomechanics in Ocular Disease, Biomolecule Transport, and Pharmacokinetics

PURPOSE

The biomechanical properties of the vitreous humor and replication of these properties to develop substitutes for the vitreous humor have rapidly become topics of interest over the last two decades. In particular, the behavior of the vitreous humor as a viscoelastic tissue has been investigated to identify its role in a variety of processes related to biotransport, aging, and age-related pathologies of the vitreoretinal interface.

METHODS

A thorough search and review of peer-reviewed publications discussing the biomechanical properties of the vitreous humor in both human and animal specimens was conducted. Findings on the effects of biomechanics on vitreoretinal pathologies and vitreous biotransport were analyzed and discussed.

RESULTS

The pig and rabbit vitreous have been found to be most mechanically similar to the human vitreous. Age-related liquefaction of the vitreous creates two mechanically unique phases, with an overall effect of softening the vitreous. However, the techniques used to acquire this mechanical data are limited by the in vitro testing methods used, and the vitreous humor has been hypothesized to behave differently in vivo due in part to its swelling properties. The impact of liquefaction and subsequent detachment of the vitreous humor from the posterior retinal surface is implicated in a variety of tractional pathologies of the retina and macula. Liquefaction also causes significant changes in the biotransport properties of the eye, allowing for significantly faster movement of molecules compared to the healthy vitreous. Recent developments in computational and ex vivo models of the vitreous humor have helped with understanding its behavior and developing materials capable of replacing it.

CONCLUSIONS

A better understanding of the biomechanical properties of the vitreous humor and how these relate to its structure will potentially aid in improving clinical metrics for vitreous liquefaction, design of biomimetic vitreous substitutes, and predicting pharmacokinetics for intravitreal drug delivery.

Quadratus Lumborum Blockade for Postoperative Analgesia in Infants and Children Following Colorectal Surgery

Background

Adult studies have indicated that the quadratus lumborum block (QLB) may provide superior analgesia compared to single-shot neuraxial and other truncal peripheral nerve blocks. The technique is being increasingly used for postoperative analgesia in children undergoing lower abdominal surgery. To date, these pediatric reports have been limited by small sample sizes, which may hinder the interpretation of results and assessment of safety. In this study, we retrospectively examined QLBs performed at a large tertiary care hospital for evidence of effectiveness and safety in the pediatric colorectal surgery population.

Methods

Patients less than 21 years of age who underwent abdominal surgery and received a unilateral or bilateral QLB over a 4-year period were identified in the electronic medical record. Patient demographics, surgery type, and QLB characteristics were retrospectively examined. Pain scores and opioid consumption were tabulated over the first 72-h postoperative period. QLB procedural complications or adverse events attributable to the regional anesthetic were obtained.

Results

The study cohort included 204 QLBs in 163 pediatric-aged patients (2 days to 19 years of age, median age of 2.4 years). The most common indication was unilateral blockade for ostomy creation or reversal. The majority of QLBs were performed using ropivacaine 0.2% with a median volume of 0.6 mL/kg. The median opioid requirement in oral morphine milligram equivalents (MMEs) was 0.7, 0.5, and 0.3 MME/kg on the first, second, and third postoperative days, respectively. Median pain scores were less than 2 over each time period. Aside from block failure (incidence 1.2%), there were no complications or postoperative adverse events related to the QLBs.

Conclusion

This retrospective review in a large cohort of pediatric patients demonstrates that the QLB can be performed safely and efficiently in children undergoing colorectal surgery. The QLB provides adequate postoperative analgesia, has a high success rate, may limit postoperative opioid consumption, and is associated with a limited adverse effect profile.

Preliminary Experience With Quadratus Lumborum Catheters for Postoperative Pain Management in Pediatric-Aged Patients With Contraindications to Epidural Anesthesia

BACKGROUND

Although neuraxial techniques such as caudal and epidural anesthesia were initially the predominant regional anesthetic technique used to provide postoperative analgesia in children, there has been a transition to the use of peripheral nerve blockade such as the quadratus lumborum block (QLB). We present preliminary experience with QL catheters for continuous postoperative analgesia in a cohort of pediatric patients following colorectal surgery.

METHODS

After institutional review board (IRB) approval, we retrospectively reviewed the records of patients who underwent major colorectal surgery and received QL catheters for postoperative analgesia. The postoperative pain control data consisted of QL catheter characteristics, anesthetic agents, adjuncts, pain scores, and opioid consumption during the postoperative period.

RESULTS

The study cohort included eight pediatric patients, ranging in age from 1 to 19 years (median age 11.8 years). The QL catheters were placed in the operating room after the induction of anesthesia. Comorbid conditions in the cohort that were contraindications to neuraxial anesthesia included spinal/vertebral malformations, presence of a ventriculoperitoneal (VP) shunt, anal atresia, tracheo-esophageal fistula (VACTERL) association, and coagulation disturbances. All patients underwent complex colorectal or genito-urologic procedures. Bilateral QL catheters were placed in six patients, and unilateral catheters were placed in two patients. Four patients received 0.5% ropivacaine and four patients received 0.2% ropivacaine of an initial bolus. The local anesthetic used for continuous infusion was 0.2% ropivacaine in five patients, 0.1% ropivacaine in two patients, and 1.5% chloroprocaine in one patient, with a median infusion rate of 0.11 mL/kg/h. QL catheter infusions were supplemented with intravenous opioids delivered by patient-controlled or nurse-controlled analgesia. The median opioid requirements in oral morphine milligram equivalents (MME) were 1.2, 1.0, 1.1, 0.5, and 0.6 MME/kg on postoperative days 1 - 5. Daily median pain scores were ≤ 2 during the 5-day postoperative course. All catheters functioned successfully and were in place for a median of 79.3 h. Other than early inadvertent removal of two catheters, no adverse effects were noted.

CONCLUSIONS

Although our preliminary data suggest the efficacy of QL catheters in providing prolonged postoperative analgesia for up to 3 - 5 days following colorectal procedures, attention needs to be directed at measures to ensure that the catheter is secured to avoid inadvertent removal.

Quantification of chemotherapy-induced changes in body composition in pediatric, adolescent, and young adult lymphoma using standard of care CT imaging

OBJECTIVES

The objective of this study was to use computed tomography (CT) imaging to quantify chemotherapy-induced changes in body composition (BC) in pediatric, adolescent, and young adult (AYA) patients with lymphoma and to compare image-derived changes in BC measures to changes in traditional body mass index (BMI) measures.

METHODS

Skeletal muscle (SkM), subcutaneous adipose tissue (SAT), and visceral adipose tissue (VAT) volumes were manually segmented using low-dose CT images acquired from a 10-year retrospective, single-site cohort of 110 patients with lymphoma. CT images and BMI percentiles (BMI%) were acquired from baseline and first therapeutic follow-up. CT image segmentation was performed at vertebral level L3 using 5 consecutive axial CT images.

RESULTS

CT imaging detected significant treatment-induced changes in BC measures from baseline to first follow-up time points, with SAT and VAT significantly increasing and SkM significantly decreasing. BMI% measures did not change from baseline to first follow-up and were not significantly correlated with changes in image-derived BC measures. Patients who were male, younger than 12 years old, diagnosed with non-Hodgkin's lymphoma, and presented with stage 3 or 4 disease gained more adipose tissue and lost more SkM in response to the first cycle of treatment compared to their clinical counterparts.

CONCLUSIONS

Standard of care CT imaging can quantify treatment-induced changes in BC that are not reflected by traditional BMI assessment. Image-based monitoring of BC parameters may offer personalized approaches to lymphoma treatment for pediatric and AYA patients by guiding cancer treatment recommendations and subsequently enhance clinical outcomes.

KEY POINTS

• Standard of care low-dose CT imaging quantifies chemotherapy-induced changes in body composition in pediatric, adolescent, and young adults with lymphoma. • Body mass index could not detect changes in body composition during treatment that were quantified by CT imaging. • Pediatric and AYA patients who were male, younger than 12 years old, and diagnosed with non-Hodgkin's lymphoma, and presented with stage 3 or 4 disease gained more adipose tissue and lost more skeletal muscle tissue in response to the first cycle of treatment compared to their clinical counterparts.

Association of Pre-procedural Anxiety with Procedure-related Pain During Outpatient Pediatric Burn Care: A Pilot Study

The relationship between preprocedural anxiety and pain is not clear but has the potential to change the way pediatric patients need to be cared for prior to burn procedures. Using results from our recent randomized clinical trial among outpatient burn patients (n=90) age 6-17 years, the objective of this subsequent analysis was to assess whether preprocedural anxiety was associated with self-reported and researcher observed pain scores. Anxiety before the dressing change was assessed using an abbreviated State-Trait Anxiety Inventory for Children (range 6-21) and reported with 95% confidence intervals (CI). Self-reported pain was reported using a Visual Analog Scale (range 0-100) and observed pain was assessed using the Face, Legs, Activity, Cry, and Consolability-revised scale. Over half of patients (58.9%) reported mild anxiety (score <12) and about 5% of patients reported severe anxiety (score >16). Younger children (6-8 years) reported higher anxiety scores than older children (15-17 years), but the difference did not achieve statistical significance (mean=12.7, 95% CI: 11.5-13.9, p=0.09). Nonparametric spearman correlation indicated that anxiety score was significantly correlated with observed pain (p=0.01) and self-reported overall pain neared statistical significance (p=0.06). In the final logistic regression of reporting moderate-to-severe pain (pain score >30), the association between anxiety scores and self-reported overall moderate-to-severe pain was statistically significant (p=0.03) when adjusting for race, healing degree, and pain medication use within 6 hours prior to burn dressing care. This pilot study provides preliminary data showing that anxiety before outpatient pediatric burn dressing changes is significantly associated with self-reported overall moderate-to-severe pain.

Association of Severe Obesity and Chronic Obstructive Pulmonary Disease With Pneumonia Following Non-Cardiac Surgery

Background

Pneumonia is the third most common surgical complication after urinary tract infection and wound infections. In addition to increased mortality, patients who develop postoperative pneumonia have a higher risk of prolonged hospital stay, intensive care unit (ICU) admissions, and higher healthcare costs. Obesity and chronic obstructive pulmonary disease (COPD) are both independent risk factors for the development and severity of postoperative pneumonia, although the combined effect of these comorbidities is unknown. Therefore, we evaluated whether the combination of severe obesity and COPD is associated with an increased risk of postoperative pneumonia.

Methods

We performed a multicenter retrospective cohort study of 365,273 patients aged 18 - 64 years who were either severely obese (body mass index (BMI) ≥ 40 kg/m²) or normal-weight (BMI between 18.6 and 24.9 kg/m²) and underwent general surgery, orthopedic surgery, neurosurgery, otolaryngology surgery, urology surgery, and vascular surgery in the American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) participating hospitals from 2014 to 2018. We evaluated the combined effect of COPD and severe obesity on the risk for postoperative pneumonia, unplanned tracheal reintubation, and extended length of stay.

Results

The co-occurrence of severe obesity and COPD appeared to have a protective effect on the risk of postoperative pneumonia. In the presence of COPD, patients with severe obesity were 14% less likely to develop pneumonia compared to their normal-weight counterparts (2.9% vs. 4.4%; adjusted relative risk (RR): 0.76; 95% confidence interval (CI): 0.60, 0.95). In addition, in the presence of COPD, severe obesity conferred a lower risk for requiring an extended length of stay (37.6% vs. 47.9%; adjusted RR: 0.83; 95% CI: 0.78, 0.89).

Conclusions

Counterintuitively, the co-occurrence of severe obesity with COPD appeared to buffer the negative impact of COPD on postoperative pneumonia, unplanned tracheal reintubation, and prolonged hospital stay after noncardiac surgery. These findings are consistent with the obesity paradox and warrant further investigations.

Anesthesia with Tricaine Methanesulfonate (MS222) and Propofol and Its Use for Computed Tomography of Red Swamp Crayfish (Procambarus clarkii)

Crayfish (Decapoda: Astacoidea and Parastacoidea) are among the few animals that have stem cells in hemolymph, with the capacity to continuously produce differentiated neuronal structures throughout life. As the use of crayfish and other invertebrates increases in biomedical research, we must develop laboratory standards and guidelines for performing clinical procedures. This manuscript presents introductory protocols for anesthesia in crayfish during diagnostic imaging. Five anesthetic protocols were evaluated: immersion in buffered tricaine methanesulfonate (MS222; 50 mg/L); immersion in buffered MS222 (150 mg/L); immersion in propofol (65 mg/L); injection of propofol (50 mg/kg); and injection of propofol (100 mg/kg) into the ventral surface of an abdominal somite. MS222 immersion (50 and 150 mg/L) had no observable effect on crayfish. After an extended period of time, immersion in propofol (65 mg/L) created a sedative effect suitable for short-term handling. Propofol injection (50 mg/kg) into the ventral surface of an abdominal somite created an effective plane of anesthesia without adverse effects during or after recovery. Propofol injection at 100 mg/kg had adverse effects and is not recommended for use in crayfish. CT imaging was performed successfully as proof of concept for handling anesthetized crayfish. These findings provide initial data for the anesthetization of crayfish used in research settings.

Novel Application of 18F-NaF PET/CT Imaging for Evaluation of Active Bone Remodeling in Diabetic Patients With Charcot Neuropathy: A Proof-of-Concept Report

Charcot neuropathic osteoarthropathy (CN) is a serious and potentially limb-threatening complication for patients with diabetes mellitus and peripheral arterial disease. In recent decades, nuclear medicine-based approaches have been used for non-invasive detection of CN; however, to date, a positron emission tomography (PET) radionuclide specifically focused on targeted imaging of active bone remodeling has not been explored or validated for patients with CN. The radionuclide 18F-sodium fluoride (NaF) has historically been used as a bone imaging probe due to its high sensitivity for targeting hydroxyapatite and bone turnover, but has not been applied in the context of CN. Therefore, the present study focused on novel application of 18F-NaF PET/computed tomography (CT) imaging to three clinical cases of CN to evaluate active bone remodeling at various time courses of CN. PET/CT imaging in all 3 cases demonstrated focal uptake of 18F-NaF in the bones of the feet afflicted with CN, with bone retention of 18F-NaF persisting for up to 5 years following surgical reconstruction of the foot in two cases. On a group level, 18F-NaF bone uptake in the CN foot was significantly higher compared to the healthy, non-CN foot (p = 0.039). 18F-NaF PET/CT imaging may provide a non-invasive tool for monitoring active bone remodeling in the setting of CN, thereby offering novel opportunities for tracking disease progression and improving treatment and surgical intervention.

Macro- and Microscale Properties of the Vitreous Humor to Inform Substitute Design and Intravitreal Biotransport

Research on the vitreous humor and development of hydrogel vitreous substitutes have gained a rapid increase in interest within the past two decades. However, the properties of the vitreous humor and vitreous substitutes have yet to be consolidated. In this paper, the mechanical properties of the vitreous humor and hydrogel vitreous substitutes were systematically reviewed. The number of publications on the vitreous humor and vitreous substitutes over the years, as well as their respective testing conditions and testing techniques were analyzed. The mechanical properties of the human vitreous were found to be most similar to the vitreous of pigs and rabbits. The storage and loss moduli of the hydrogel vitreous substitutes developed were found to be orders of magnitude higher in comparison to the native human vitreous. However, the reported modulus for human vitreous, which was most commonly tested in vitro, has been hypothesized to be different in vivo. Future studies should focus on testing the mechanical properties of the vitreous in situ or in vivo. In addition to its mechanical properties, the vitreous humor has other biotransport mechanisms and biochemical functions that establish a redox balance and maintain an oxygen gradient inside the vitreous chamber to protect intraocular tissues from oxidative damage. Biomimetic hydrogel vitreous substitutes have the potential to provide ophthalmologists with additional avenues for treating and controlling vitreoretinal diseases while preventing complications after vitrectomy. Due to the proximity and interconnectedness of the vitreous humor to other ocular tissues, particularly the lens and the retina, more interest has been placed on understanding the properties of the vitreous humor in recent years. A better understanding of the properties of the vitreous humor will aid in improving the design of biomimetic vitreous substitutes and enhancing intravitreal biotransport.

Glutathione Improves the Antioxidant Activity of Vitamin C in Human Lens and Retinal Epithelial Cells: Implications for Vitreous Substitutes

PURPOSE

Tissues in the eye are particularly susceptible to oxidative damage due to light exposure. While vitamin C (ascorbic acid) has been noted as a vital antioxidant in the vitreous humor, its physiological concentration (1-2 mM) has been shown to be toxic to retinal and lens epithelial cells in in vitro cell culture. We have explored adding vitamin C to hydrogel vitreous substitutes as a potential therapeutic to prevent oxidative damage to intraocular tissues after vitrectomy. However, vitamin C degrades rapidly even when loaded at high concentrations, limiting its long-term effectiveness. Glutathione, another antioxidant found abundantly in the lens at concentrations of 2-10 mM, was proposed to be used in conjunction with vitamin C.

METHODS

Cell viability and reactive oxygen species activity of human retinal and lens epithelial cells treated with various combinations of vitamin C, glutathione, hydrogen peroxide, and a hydrogel vitreous substitute were determined using CellTiter-Glo luminescent cell viability assay and dichlorofluorescein assay, respectively. The vitamin C remaining in hydrogel vitreous substitute or glutathione-vitamin C solutions was determined using a microplate reader at 265 nm wavelength, compared against standard solutions with known concentrations.

RESULTS

Glutathione protected the lens and retinal cells from the negative effect of vitamin C on cell viability and prolonged the antioxidant effect of vitamin C in vitro. While the detected reading of pure vitamin C solution decreased rapidly from 100% to 10% by 3 days, glutathione provided a significant extension to vitamin C stability, with 70% remaining after 14 days when the glutathione was used at physiological concentrations found in the lens (2-10 mM).

CONCLUSIONS

These results indicate glutathione might be an effective addition to vitamin C in intraocular implants, including potential vitreous substitutes, and warrants additional studies on the effectiveness of the vitamin C - glutathione combination in preventing oxidative stress post-vitrectomy.

Accommodative tissues influence the shape of the cornea and potentially drive corneal morphogenesis

This study investigates whether the presence of accommodative tissues biomechanically influences the shape of the cornea and potentially drives corneal morphogenesis during embryonic ocular development. Porcine eyes were subjected to an internal pressure simulating intraocular pressure. Ocular geometry was evaluated using a corneal topographer and digital cameras before and after dissection of the accommodative tissues. A computational model of the porcine eye was constructed and loaded by an internal pressure representing intraocular pressure. Eye shape was evaluated in models with and without the ciliary body. The porcine model was generalized to the human model, simplified model, or embryonic model with different ocular tissue shapes, sizes, and stiffnesses. Experimental data showed that, even in the six-month-old pig eye, the average corneal radius of curvature increased after the removal of accommodative tissues compared to sham controls (p = 0.002). Computational results agreed with the experimental data and further suggested that the change in corneal radius is greater when the tissue stiffness is low and the intraocular pressure is high, regardless of the geometry and size of the eye components. Using a combined in vitro and in silico approach, this study explores the biomechanical influence of the accommodative tissues and related loads on the cornea and offers additional factors that might influence the shape of the cornea.

Rheological Properties and Age-Related Changes of the Human Vitreous Humor

The vitreous humor is a fragile, transparent hydrogel situated between the lens and the retina, occupying 80% of the eye's volume. Due to its viscoelastic behavior, the vitreous serves as a mechanical damper for the eye, absorbing impacts, and protecting the lens and retina. The vitreous liquefies with age, which compromises its function as a shock absorber and causes complications including retinal detachment, macular holes, and vitreous hemorrhage. Studies on the viscoelastic properties of the vitreous have been limited. Rheological testing of the vitreous has commonly been done on non-primate mammalian species. Human vitreous rheological properties have been previously reported; however, various measurement techniques were used, resulting in data that differed by orders of magnitude. Shear rheometry is commonly used to characterize soft tissues and hydrogels such as the vitreous humor. However, no human vitreous rheological data have been reported using this technique, preventing direct comparison to other published work. Additionally, no age-related changes in the mechanical properties of the human vitreous humor have been reported. Human vitreous samples (n = 39, aged 62 ± 15 years) were tested using a shear rheometer. Small amplitude oscillatory shear and creep experiments were performed. The linear viscoelastic region of the human vitreous was found to be below 1% strain. The solid phase of the old human vitreous was found to be stiffer than the young human vitreous and the porcine vitreous. The stiffness of the human vitreous gel also appeared to be positively correlated with age. Vitreous dehydration due to a decrease in hyaluronic acid concentration with age was proposed to cause the stiffening of the solid phase of the vitreous gel. Vitreous liquefaction, therefore, might be characterized as a simultaneous increase in liquid volume and localized stiffening of the vitreous gel. The phase separation of the vitreous humor with age has been hypothesized as the cause of many vitreous-related complications. This study provides viscoelastic properties and age-related changes of the human vitreous humor, which will aid in the design of biomimetic vitreous substitutes, enhancement in analyzing intravitreal transport of therapeutics, and understanding the pathological conditions of the vitreous humor.