Combined spinal/caudal catheter anesthesia: extending the boundaries of regional anesthesia for complex pediatric urological surgery.

BACKGROUND: Spinal anesthesia (SA) is an established anesthetic technique for short outpatient pediatric urological cases. To avoid general anesthesia (GA) and expand regional anesthetics to longer and more complex pediatric surgeries, the authors began a program using a combined spinal/caudal catheter (SCC) technique. STUDY DESIGN: The authors retrospectively reviewed the charts of all patients scheduled for surgery under SCC between December 2016 and April 2018 and recorded age, gender, diagnosis, procedure, conversion to GA/airway intervention, operative time, neuraxial and intravenous medications administered, complications, and outcomes. The SCC technique typically involved an initial intrathecal injection of 0.5% isobaric bupivacaine followed by placement of a caudal epidural catheter. At the discretion of the anesthesiologist, patients received 0.5 mg per kilogram of oral midazolam approximately 30 min prior to entering the operating room. One hour after the intrathecal injection, 3% chloroprocaine was administered via the caudal catheter to prolong the duration of surgical block. Intra-operative management included either continuous infusion or bolus dosing of dexmedetomidine, as needed, for patient comfort and to optimize surgical conditions. Prior to removal of caudal catheter in the post-anesthesia care unit, a supplemental bolus dose of local anesthesia was given through the catheter to provide prolonged post-operative analgesia. RESULTS: Overall, 23 children underwent attempted SCC. SA was unsuccessful in three patients, and surgery was performed under GA. The remaining 20 children all had successful SCC placement. There were 11 girls and nine boys, with a mean age of 16.5 months (3.3-43.8). Surgeries performed under SCC included seven ureteral reimplantations, two ureterocele excisions/reimplantations, two megaureter repairs, four first-stage hypospadias repairs, one distal hypospadias repair, one second-stage hypospadias repair, two feminizing genitoplasties, and one open pyeloplasty. Average length of surgery was 109 min (range 63-172 min). Pre-operative midazolam was given in 13/20 (65%). All SCC patients were spontaneously breathing room air during the operation, and there were no airway interventions. Only one SCC patient received opioids intra-operatively. There were no intra-operative or perioperative complications. DISCUSSION: This pilot study shows that the technique of SCC allows one to do more complex urologic surgery under regional anesthesia than what would be possible under pure SA alone. The main limitations of the study include the relatively small number of patients and the small median length of the operative procedures. As a proof of concept, however, this does show that complex genital surgery bladder level procedures such as ureteral reimplantation can be performed under regional anesthesia. CONCLUSION: SCC allows for more complex surgeries to be performed exclusively under regional anesthesia, thus obviating the need for airway intervention, minimizing or eliminating the use of opioids, and thus avoiding known and potential risks associated with GA. The latter is of particular importance given current concerns regarding hypothetical neurocognitive effects of GA on children aged below 3 years.

Benefits of spinal anesthesia for urologic surgery in the youngest of patients.

INTRODUCTION: Increasing concerns regarding potential negative effects of early use of inhalational and intravenous anesthetics on neurocognitive development have led to a growing interest in alternative forms of anesthesia in infants. The study institution's outcomes with spinal anesthesia (SA) for urologic surgery in infants aged less than 90 days are reported and their outcomes with a matched cohort of patients who underwent general anesthesia (GA) are compared. METHODS: This is a retrospective single-center analysis. Patients aged less than 90 days who underwent SA for four urologic surgeries (inguinal hernia repair, scrotal exploration, posterior urethral valve ablation, and ureterocele puncture) were identified from the study institution's SA database. An age- and procedure-matched control cohort was identified from a list of patients who underwent the aforementioned four procedures under GA since 2013. Outcomes of interest included success rate of SA, complications from spinal placement, narcotic use, need for supplemental medications and oxygen, and length of hospital stay. RESULTS: Forty patients were identified; 20 in the SA and 20 in the GA group. Mean patient age was 54 (standard deviation, 35) days. There were no significant differences between the groups in age, gender, weight, history of prematurity, or presence of comorbidities. Eighty percent of SA patients had successful SA; reasons for conversion to GA included failure of spinal needle placement (75%) and agitation during operative procedure (25%). Ninety-six percent of patients who received GA (primarily or converted) had an endotracheal tube (ETT) placed. No patient in the SA group had a complication from spinal needle placement. Patients in the SA group were less likely to receive narcotics during the operative procedure (P = 0.001) and also had a lower mean morphine equivalent dose/kilogram (P = 0.002). Patients in the SA group were also less likely to receive any supplemental medications during the operative procedure (P = 0.001), particularly intravenous corticosteroids (P < 0.001). There were no significant differences in the length of hospital stay. CONCLUSIONS: The use of SA has clear advantages for this medically vulnerable population. For the majority of patients, it obviates the need for ETT placement and airway management and avoids the potential negative effects of GA on neurocognitive development. It also decreases the use of narcotics and other supplemental medications. In scenarios in which the benefit of surgery must be weighed against the risk of GA, such as neonatal torsion, SA may allow a paradigm shift in the timing of surgery.

Urinary antimicrobial peptides: Potential novel biomarkers of obstructive uropathy.

INTRODUCTION: Antimicrobial peptides (AMPs) have historically been evaluated for their role in protecting against uropathogens. However, there is mounting evidence to support their expression in noninfectious injury, with unclear meaning as to their function. It is possible that AMPs represent urothelial injury. Urinary tract obstruction is known to alter the urothelium; however, AMPs have not been evaluated for expression in this noninfectious injury. OBJECTIVE: A pilot study to compare urinary AMP expression in children undergoing surgical intervention for ureteropelvic junction obstruction (UPJO) with nonobstructed controls. STUDY DESIGN: Bladder urine was collected from consenting/assenting pediatric patients with UPJO at intervention. Control bladder urines were obtained from age-matched and sex-matched healthy children without known obstruction or infection. Enzyme-linked immunosorbent assays were run for the following AMPs: ß defense 1 (BD-1), neutrophil gelatinase-associated lipocalin (NGAL), cathelicidin (LL-37), hepatocarcinoma-intestine-pancreas/pancreatitis-associated protein (HIP/PAP), and human α defensin 5 (HD-5); and normalized to urine creatinine. Results were analyzed with Student's t-test or Mann-Whitney U test, when appropriate, and receiver operating characteristic curves. A P-value of <0.05 was considered significant. RESULTS: Thirty bladder urine samples were obtained from children with UPJO at the time of decompressive intervention. Mean patient age was 4.7 years (range 0.3-18.4); 20 (67%) patients were male. Fifteen bladder urine samples were obtained from age-matched and sex-matched controls. Urinary AMP levels were significantly higher in UPJO patients than controls for BD-1 (P = 0.015), NGAL (P < 0.001), LL-37 (P < 0.001), and HIP/PAP (P = 0.046). Optimal threshold values of these AMPs were determined, with each demonstrating significant odds ratios of predicting urinary obstruction. DISCUSSION: Certain urinary AMPs are altered even in noninfectious urinary tract pathology. This represents a novel induction of AMP expression, as the current study is the first to report elevations in BD-1 and HIP/PAP in urinary tract obstruction. This suggests other roles for these AMPs outside of their antimicrobial properties, and likely is a reflection of the urothelial and tubular stress resulting from obstructive uropathy. CONCLUSIONS: Induction of AMPs BD-1, NGAL, LL-37, and HIP/PAP was found to occur in urinary tract obstruction. Further evaluation of AMP expression as a biomarker of uroepithelial injury outside of infection is indicated.

The modified Ulaanbaatar procedure: Reduced complications and enhanced cosmetic outcome for the most severe cases of hypospadias.

INTRODUCTION/OBJECTIVE: Proximal hypospadias is one of the most challenging conditions that pediatric urologists have to deal with. Many procedures have been devised over the years, but nothing has been proven to be the best option. Although there have been some attempts at correcting severe hypospadias in one procedure, most have advocated a staged approach. The classic approach - laying penile skin or a graft within a split glans followed by glanuloplasty at the second stage - by definition requires two operations on the glans. In the Ulaanbaatar procedure the distal glanular urethra is constructed at the first stage, allowing for a single glans procedure and thus potentially better cosmetic outcomes. The present study discusses experience with the Ulaanbaatar procedure for severe hypospadias. STUDY DESIGN: The study retrospectively reviewed every child who underwent both stages of this procedure at the present institution. It reviewed age, associated diagnoses, surgical technique and outcomes. SURGICAL TECHNIQUE: The first stage was analogous to a classic first-stage procedure with regard to division of the urethral plate and correction of penile curvature. However, an island flap of preputial skin was mobilized and tubularized to create the glanular urethra. No attempt was made to bridge the native meatus and this reconstructed urethra, and the remaining penile skin was placed between the two. The second stage was performed 6 months later by tubularizing the penile skin between the two meatuses. RESULTS: The series consisted of 34 boys. Mean age at surgery was 18.3 months (range 6-118). Nineteen underwent evaluation for genital ambiguity at birth (56%). Thirty (88%) received pre-operative testosterone or human chorionic gonadotropin (HCG). After urethral plate transection, persistent curvature was addressed during the first stage, with dorsal plication in 12 (35%), urethral plate transection alone in six (18%) or ventral grafting with small intestinal submucosa in 16 (47%). Twenty-three boys (67%) had the neourethra tunneled through the glans, and 11 (33%) had the glans split followed by glanuloplasty. Average time between the two stages was 7 months (range 4.0-13.9). Four patients (12%) developed urethral diverticula that required repair. One developed recurrent epididymitis related to an abnormal ejaculatory duct (no stricture) and underwent vasectomy. No patient developed a fistula. Mean length of follow-up was 15.2 months (range 0.3-55.5). DISCUSSION: This modification of the classic staged hypospadias repair may allow for better cosmetic outcome, since the majority of boys required no formal glanuloplasty. There were reduced complications, perhaps because the urethral defect acted like a controlled fistula, allowing for better tissue healing prior to final urethral reconstruction.

Interdisciplinary pain management is beneficial for refractory orchialgia in children.

INTRODUCTION: Idiopathic testicular/groin pain can be a difficult entity for children, their families, and caregivers. The role of interdisciplinary pain management has previously been demonstrated in treating chronic orchialgia at the present pediatric pain clinic. OBJECTIVE: To evaluate the role of interdisciplinary pain management in managing refractory orchialgia. It was hypothesized that children with refractory orchialgia might respond well. Interdisciplinary care was defined as that which crosses two medical disciplines such as a surgical specialty and specialist in analgesia. SUBJECTS AND METHODS: Pediatric patients were identified who were: ≥ 10 years old; evaluated in the pediatric urology clinic between 2002 and 2012; were diagnosed wtih ICD code 608.9 or had the diagnosis of male genital disorder NOS. Children were included if they presented with orchialgia without an identifiable cause and failed conservative management (rest, scrotal support, Sitz bath, timed voiding, constipation avoidance) including conventional anti-nociceptive analgesics (acetaminophen, non-steroidal anti-inflammatory drugs, opioids). Patient electronic medical records were reviewed retrospectively. RESULTS: Twenty-two children met inclusion criteria. Mean age was 13.7 years (range 10-17). Nearly half (45%) of the children had chronic medical conditions such as asthma, allergies, and obesity. Twenty-one of the 22 children were referred to the pediatric pain clinic; 15 were evaluated, and one refused treatment. All children evaluated in the pediatric pain clinic were initially offered an empiric anti-neuropathic anti-convulsant (i.e. gabapentin) and/or an anti-depressant (i.e. amitriptyline) before being offered a nerve block. Of the 14 children accepting treatment in the pediatric pain clinic, six were treated solely with an empiric anti-neuropathic anti-convulsant and/or anti-depressant; eight received medications followed by nerve block (seven ilioinguinal-iliohypogastric blocks, one spinal and ilioinguinal-iliohypogastric block) (see Fig. 1). A total of eight of the 14 children (57%) treated by the pain clinic had resolution of pain, with 50% of those treated with medications alone (three out of six children) responding (two responding to gabapentin and a tricyclic antidepressant, one to gabapentin alone); and five out of eight (63%) treated with medications and then nerve block (ilioinguinal-iliohypogastric block) responding. Of the eight children undergoing nerve block, five required more than one block. The time between each block ranged from 4 to 22.6 weeks. Response to nerve block required an average of 1.4 procedures (range 1-2); mean follow-up after nerve block was 2.4 months (range 0.1-4.8). DISCUSSION: Children with refractory orchialgia often have comorbidities that suggest a multidisciplinary approach would be useful for treating them. The present study found that the majority of children with refractory orchialgia treated in the pediatric pain clinic responded to management. Major limitations, however, included small cohort size and short follow-up, particularly in those children undergoing nerve block. There was also no objective assessment of pain improvement or improvement in quality of life, which could be rectified with a prospective study. CONCLUSION: Collaboration and early referral for interdisciplinary pain management as one of these multidisciplinary approaches may help to coordinate care and ease patient suffering.

Study of feed temperature control of chromatography using computional fluid dynamics simulation.

Recently preparative high-performance liquid chromatography (HPLC) has been used more and more frequently to separate drugs and natural substances. However, large-scale HPLC easily tends to reduce the yield and purity of the product. Hydrodynamic and heat factors play an important roles. Generally, in a large-scale HPLC column, the tracer profile inside column will take on a parabolic shape because of the distributor, which will impact the separation performance of the column. With the inlet temperature suitably lower than the wall temperature, this situation could be improved to some extent. In this work, some experiments were conducted using HPLC, with a column 10 cm in diameter to determine the optimal temperature difference between wall and inlet temperatures. The wall temperature was fixed at about 30 degrees C and the inlet temperature varied from 15 to 30 degrees C. The flow-rate of the eluent, methanol, was 300 ml/min. The experimental result was simulated using CFD software FLUENT 4.4.4. The simulated temperature field fitted the experimental one very well and the simulated flow, temperature and tracer distribution inside column could provide good explanation of separation performance under different conditions. In addition, the simulation could at least approximately predict the optimal temperature difference.

Chromatographic resolution of the chiral isomers of several beta-blockers over cellulose tris(3,5-dimethylphenylcarbamate) chiral stationary phase.

The optical resolution of seven beta-blockers which have in common the N-isopropyl-3-aryloxy-2-hydroxypropylamine moiety was carried out by HPLC using the cellulose tris(3,5-dimethylphenylcarbamate) chiral stationary phase to quantitatively characterize the enantioselectivity of these compounds. The capacity factors and separation factors at different column temperature were determined with some qualitative trends derived. A compensation effect was observed for these compounds where there exists an approximately linear relationship between the enantiomeric differences in enthalpic and entropic energies.

Chromatographic evaluation of sorption and diffusion characteristics of glucose, maltose and maltotriose in silica gels.

Liquid chromatographic techniques were employed to evaluate the sorption and diffusion characteristics of glucose, maltose and maltotriose in silica gel. The equilibrium constants were found to decrease with increasing molecular size. The determined diffusion coefficient of glucose is comparable to that in the literature. The pore diffusivities decrease with increasing size of the carbohydrates at all temperatures.