Peripheral nerve stimulation through a 'dry' peripheral nerve catheter for shoulder analgesia: a case report.

Revision shoulder surgery can pose significant analgesic challenges as locoregional blocks are often avoided to enable early recognition of iatrogenic nerve injuries. Our case describes the utilisation of pre-operative and intra-operative low-frequency percutaneous peripheral nerve stimulation via a 'dry' interscalene catheter, inserted pre-operatively for a patient presenting for revision total shoulder arthroplasty who was experiencing significant shoulder joint pain despite a prior total shoulder arthroplasty. The clinical considerations and safety aspects are discussed further.

Pain management using a novel hybrid technique of perineural stimulation combined with regional anaesthesia through a stimulating perineural catheter for below knee amputation.

Pain after amputation can be difficult to manage due to its complex aetiology. A multimodal approach to analgesia, including regional anaesthetic techniques, is advised. However, optimal pain management cannot always be achieved, and high doses of opioid analgesics may contribute to adverse effects. We describe the management of an elderly patient with significant co-morbidities undergoing below knee amputation. Pre-operatively, a popliteal sciatic stimulating perineural catheter and a femoral non-stimulating perineural catheter were placed. When pain control was suboptimal on the first postoperative day, a combination of local anaesthetic and a brief period of peripheral nerve stimulation through the sciatic stimulating perineural catheter was used to augment pain control, thereby avoiding additional opioid use. Although nerve stimulation utilising specialised equipment, such as percutaneous stimulator electrodes, has been previously described in acute pain medicine, we demonstrate the use of a novel hybrid technique which combines nerve stimulation through a perineural catheter and local anaesthetic. Further research is warranted to explore the utility of this neuromodulation technique in clinical practice.

Successful postoperative analgesia with ilio-inguinal nerve block following sclerotherapy for a labial venous malformation.

Though ilio-inguinal nerve block has been commonly utilised in male urologic surgery, a single injection ilio-inguinal nerve block alone has not previously been reported for analgesia of the vulva. In this report, we describe the case of a 14-year-old girl undergoing sclerotherapy of a venous malformation affecting the labia majora and minora. After induction of anaesthesia, we performed an ultrasound-guided ilio-inguinal nerve block using a total volume of 15 ml of ropivacaine 0.2% with 1 µg.ml-1 dexmedetomidine which provided effective postoperative analgesia. Though the patient received intravenous analgesia intra-operatively and had an inpatient bed reserved in anticipation of severe postoperative pain, she required no further analgesia and was discharged home following 2 hours in the postoperative anaesthesia care unit. With the additional use of dexmedetomidine resulting in prolonged efficacy of the block, the patient reported effective postoperative relief for approximately 30 hours, solely using ibuprofen for pain relief. This case reminds clinicians that the ilio-inguinal nerve block may provide benefit not only for male urologic surgery but also for procedures involving the external female genitalia, with extended analgesia with the use of dexmedetomidine.

Comparison of inhaled versus intravenous anesthesia for laryngoscopy and laryngeal electromyography in a rat model.

BACKGROUND: Propofol and remifentanil intravenous combination is one popular form of total intravenous anesthesia (TIVA) in mainstream clinical practice, but it has rarely been applied to a rat model for laryngoscopy and laryngeal electromyography (LEMG). Our objective was to establish a safe and reproducible general anesthetic protocol for laryngoscopy and endoscopic LEMG in a rat model. Our hypothesis is that TIVA allows a minimally morbid, and feasible laryngoscopy and LEMG. METHODS: Sprague Dawley rats were subjected to either inhalational anesthesia (IA) (isoflurane) or TIVA (propofol and remifentanil) and underwent laryngoscopy and LEMG. The primary outcome was a complete minimally interrupted rigid laryngoscopy and obtaining reproducible motor unit potentials from the posterior cricoarytenoid muscles. The secondary outcome was morbidity and mortality. RESULTS: Seventeen out of twenty-two rats underwent both TIVA and IA. Only two underwent IA only. All nineteen rats that underwent IA had a successful experiment. Seventeen rats underwent TIVA, however, only nine completed a successful experiment due to difficulty achieving a surgical plane, and respiratory events. Upon comparing the success of the two anaesthetic regimens, IA was superior to TIVA (P = 0.0008). There was no statistical difference between the amplitudes (p = 0.1985) or motor units burst duration (p = 0.82605) of both methods. Three mortalities were encountered, one of which was due to lidocaine toxicity and two were during anesthetic induction. Respiratory related morbidity was encountered in two rats, all seen with TIVA. CONCLUSIONS: TIVA is not an ideal anesthetic regimen for laryngeal endoscopy and LEMG in rat models. Contrary to our hypothesis, IA did not affect the quality of the LEMG and allowed a seamless rigid endoscopy.

Application of the 4-D XCAT Phantoms in Biomedical Imaging and Beyond.

The four-dimensional (4-D) eXtended CArdiac-Torso (XCAT) series of phantoms was developed to provide accurate computerized models of the human anatomy and physiology. The XCAT series encompasses a vast population of phantoms of varying ages from newborn to adult, each including parameterized models for the cardiac and respiratory motions. With great flexibility in the XCAT's design, any number of body sizes, different anatomies, cardiac or respiratory motions or patterns, patient positions and orientations, and spatial resolutions can be simulated. As such, the XCAT phantoms are gaining a wide use in biomedical imaging research. There they can provide a virtual patient base from which to quantitatively evaluate and improve imaging instrumentation, data acquisition, techniques, and image reconstruction and processing methods which can lead to improved image quality and more accurate clinical diagnoses. The phantoms have also found great use in radiation dosimetry, radiation therapy, medical device design, and even the security and defense industry. This review paper highlights some specific areas in which the XCAT phantoms have found use within biomedical imaging and other fields. From these examples, we illustrate the increasingly important role that computerized phantoms and computer simulation are playing in the research community.

3D collagen architecture induces a conserved migratory and transcriptional response linked to vasculogenic mimicry.

The topographical organization of collagen within the tumor microenvironment has been implicated in modulating cancer cell migration and independently predicts progression to metastasis. Here, we show that collagen matrices with small pores and short fibers, but not Matrigel, trigger a conserved transcriptional response and subsequent motility switch in cancer cells resulting in the formation of multicellular network structures. The response is not mediated by hypoxia, matrix stiffness, or bulk matrix density, but rather by matrix architecture-induced ß1-integrin upregulation. The transcriptional module associated with network formation is enriched for migration and vasculogenesis-associated genes that predict survival in patient data across nine distinct tumor types. Evidence of this gene module at the protein level is found in patient tumor slices displaying a vasculogenic mimicry (VM) phenotype. Our findings link a collagen-induced migration program to VM and suggest that this process may be broadly relevant to metastatic progression in solid human cancers.

Perioperative management of the obese surgical patient.

INTRODUCTION: The escalation in the prevalence of obesity throughout the world has led to an upsurge in the number of obese surgical patients to whom perioperative care needs to be delivered. SOURCES OF DATA: After determining the scope of the review, the authors used PubMed with select phrases encompassing the words in the scope. Both preclinical and clinical reports were considered. AREAS OF AGREEMENT: There were no controversies regarding preoperative management and the intraoperative care of the obese surgical patient. AREAS OF CONTROVERSY: Is there a healthy obese state that gives rise to the obesity paradox regarding postoperative complications? GROWING POINTS: This review considers how to prepare for and manage the obese surgical patient through the entire spectrum, from preoperative assessment to possible postoperative intensive care. AREAS TIMELY FOR DEVELOPING RESEARCH: What results in an obese patient developing 'unhealthy' obesity?

Retrospective analysis of the incidence of epidural haematoma in patients with epidural catheters and abnormal coagulation parameters.

BACKGROUND: Epidural haematoma is a rare but potentially catastrophic complication associated with epidural catheterization. The times of insertion and removal of epidural catheters are high-risk periods for epidural haematoma formation, especially with abnormal coagulation parameters. There is a lack of data on the incidence of epidural haematoma in patients with abnormal coagulation parameters. METHODS: A retrospective analysis was undertaken from 2002 to 2009 on patients with an epidural catheter. Queries were performed on the coagulation parameters for the dates of placement and removal of the catheters and on all documented epidural haematoma cases. RESULTS: During the study period, 11 600 epidural catheters were placed. In the setting of abnormal coagulation parameters, 278 (2.4%) epidural catheters were placed and 351 (3%) were removed. Two epidural haematomas occurred; both patients had epidural catheters and spinal drains placed for vascular procedures with abnormal coagulation parameters after operatation. The haematomas occurred after removal of the catheters. Based on our study, the incidence of epidural haematoma in patients with abnormal coagulation parameters is 1 in 315 patients, with the lower limit of the 95% confidence interval at 87 and the upper limit at 2597. CONCLUSIONS: The risk of epidural haematoma is clearly elevated with abnormal coagulation parameters. Our data suggest that as the incidence of epidural haematoma with neuraxial access in patients with abnormal coagulation is not 100%, individual risk-benefit evaluations are warranted.

Sublingual ultrasound as an assessment method for predicting difficult intubation: a pilot study.

Current methods to assess the airway before tracheal intubation are variable in their ability to predict a difficult airway accurately. We hypothesised that sublingual ultrasound could provide additional information to predict a difficult airway with greater success than current methods. We recruited 110 patients to perform sublingual ultrasound on themselves following brief instruction. Ability to view the hyoid bone on sublingual ultrasound, mouth opening distance, thyromental distance, neck mobility, size of mandible and modified Mallampati classification were recorded and assessed for ability to predict a difficult intubation based on the grade of laryngoscope. Visibility of the hyoid using ultrasound was associated with a laryngoscopic grade of 1-2 (p < 0.0001), and (p < 0.0001) had a positive likelihood ratio of 21.6 and a negative likelihood ratio of 0.28. Each of the other methods had considerably lower positive likelihood ratios and lower sensitivity. Our results suggest that sublingual ultrasound is a potential tool for predicting a difficult airway in addition to conventional methods.

The effects of general anaesthesia on nerve-motor response characteristics (rheobase and chronaxie) to peripheral nerve stimulation.

Using a simple surface nerve stimulation system, I examined the effects of general anaesthesia on rheobase (the minimum current required to stimulate nerve activity) and chronaxie (the minimum time for a stimulus twice the rheobase to elicit nerve activity). Nerve stimulation was used to elicit a motor response from the ulnar nerve at varying pulse widths before and after induction of general anaesthesia. Mean (SD) rheobase before and after general anaesthesia was 0.91 (0.37) mA (95% CI 0.77-1.04 mA) and 1.11 (0.53) mA (95% CI 0.92-1.30 mA), respectively. Mean (SD) chronaxie measured before and after general anaesthesia was 0.32 (0.17) ms (95% CI 0.26-0.38 ms) and 0.29 (0.13) ms (95% CI 0.24-0.33 ms), respectively. Under anaesthesia, rheobase values increased by an average of 20% (p = 0.05), but chronaxie values did not change significantly (p = 0.39). These results suggest that threshold currents used for motor response from nerve stimulation under general anaesthesia might be higher than those used in awake patients.