Use of near infrared spectroscopy to detect impaired tissue oxygen saturation in patients with complex regional pain syndrome type 1.

PURPOSE: Deep tissue hypoxia has been hypothesized in the pathogenesis of complex regional pain syndrome type 1 (CRPS 1) for some patients. The purpose of this study was to determine if near-infrared spectroscopy (NIRS) could detect differences in deep tissue oxygen saturation (StO2) and microcirculatory function in the hands of patients with CRPS 1. METHODS: Tissue oxygen saturation was evaluated at baseline and during an ischemia reperfusion challenge using vascular occlusion testing (VOT) in affected vs unaffected hands of patients with unilateral upper limb CRPS 1. A non-randomized experimental study design was used with baseline StO2 as the primary outcome measure. Secondary outcome measures were occlusion and reperfusion slopes from VOT. Values were compared with the unaffected, contralateral hand and with the dominant and non-dominant hands of sex and age-matched volunteers. Correlations between values derived from NIRS and measures of pain and function from the Brief Pain Inventory (BPI) and the Disability of the Arm, Shoulder and Hand (DASH) questionnaires were explored. RESULTS: Independent of handedness, the baseline StO2 of the affected hands of ten CRPS 1 patients was significantly lower than that of their unaffected hands (-5.8%; 95% confidence interval [CI] -10.6 to -1.0; P = 0.02). The baseline StO2 of affected CRPS 1 hands was also significantly lower than the non-dominant hands of ten volunteers (-7.3%; 95% CI -12.4 to -2.3; P = 0.007). Differences in VOT occlusion and reperfusion slopes did not reveal changes that could be uniquely attributed to CRPS 1. No significant correlations were detected between values derived from VOT and values for pain and function obtained from BPI and DASH questionnaires for patients with CRPS 1. CONCLUSIONS: Hands of patients affected by CRPS 1 of the upper limb showed significantly lower StO2 compared with their unaffected contralateral hand as well as the hands of control subjects. This trial was registered at: ClinicalTrials.gov: NCT01586377.

Ultrasound-guided suprascapular nerve block: a correlation with fluoroscopic and cadaveric findings.

PURPOSE: Previous work on the ultrasound-guided injection technique and the sonoanatomy of the suprascapular region relevant to the suprascapular nerve (SSN) block suggested that the ultrasound scan showed the presence of the suprascapular notch and transverse ligament. The intended target of the ultrasound-guided injection was the notch. The objective of this case report and the subsequent cadaver dissection findings is to reassess the interpretation of the ultrasound images when locating structures for SSN block. CLINICAL FEATURES: A 45-yr-old man with chronic shoulder pain received an ultrasound-guided SSN block using the suprascapular notch as the intended target. The position of the needle was verified by fluoroscopy, which showed the tip of the needle well outside the suprascapular notch. Similar ultrasound-guided SSN blocks were performed in two cadavers. Dissections were performed which showed that the needle tips were not at the suprascapular notch but, more accurately, were close to the SSN but at the floor of the suprascapular fossa between the suprascapular and spinoglenoid notch. CONCLUSION: Our fluoroscopic and cadaver dissection findings both suggest that the ultrasound image of the SSN block shown by the well-described technique is actually targeting the nerve on the floor of the suprascapular spine between the suprascapular and spinoglenoid notches rather than the suprascapular notch itself. The structure previously identified as the transverse ligament is actually the fascia layer of the supraspinatus muscle.

Proximal splenic artery embolization in the management of splenic rupture.

OBJECTIVE: To report the use of proximal splenic artery embolization for management of spontaneous splenic rupture. DESIGN: Case report and literature review. SETTING: A tertiary pediatric critical care unit in a university teaching hospital. INTERVENTIONS: Proximal splenic artery embolization. MEASUREMENTS AND MAIN RESULTS: An 8-yr-old boy presented with abdominal pain radiating to the left shoulder 9 days after completing induction chemotherapy for acute lymphoblastic leukemia. Imaging revealed a splenic rupture with parenchymal and subcapsular hematomas, with no evidence of active extravasations. The patient was admitted to the pediatric critical care unit for close hemodynamic monitoring and frequent measurements of hemoglobin. His lowest recorded hemoglobin and hematocrit were 63 g/L and 0.19 L/L, respectively. Posttransfusion of packed red blood cells, he was taken to interventional radiology for proximal splenic artery embolization under moderate sedation. Several coils were successfully placed in the proximal splenic arterial system resulting in a marked reduction of splenic blood flow without disruption of collaterals. The patient recovered well from proximal splenic artery embolization in the pediatric critical care unit and experienced short lasting abdominal pain and fever for 1 day. He was discharged home 4 days after the procedure and follow-up imaging showed resolving hematomas with preserved splenic blood flow. CONCLUSION: Proximal splenic artery embolization in children may be a safe therapeutic alternative to either conservative or surgical management in spontaneous splenic rupture. Preservation of splenic tissue with a reduced risk of repeated hemorrhage can be obtained with proximal splenic artery embolization.

Randomized controlled trial comparing pudendal nerve block under ultrasound and fluoroscopic guidance.

BACKGROUND: Although fluoroscopy is an established imaging modality for pudendal nerve block, ultrasound (US) technique allows physicians better visualization of anatomic structures. This study aimed to compare the effectiveness and safety between the US- and fluoroscopy-guided techniques. METHODS: A randomized, single-blind, split-plot design was used to conduct the study. Twenty-three patients undergoing bilateral pudendal nerve blocks received US-guided injections to either the left or right side, whereas the contralateral side received a fluoroscopic-guided injection in randomized sequence. Injections consisted of 4 mL of 0.5% bupivacaine and 40 mg methylprednisone. The primary outcome was the success of the block in the distribution of the pudendal nerve along the perineum, rated as either absent, moderate, or strong. Secondary outcomes were the time to administer the blocks, quality of visualization of anatomic structures using US and fluoroscopy, distance of the final US-guided needle position from the ischial spine, and incidence of adverse effects. RESULTS: No differences in the degree of neural blockade were noted between US- or fluoroscopic-guided techniques for either temperature or pinprick blockade. Time to complete the procedure was significantly longer using US compared with fluoroscopy (219 [SD, 65] and 428 [SD, 151] secs, P < 0.0001). No significant differences were noted regarding the occurrence of adverse effects between the 2 techniques. CONCLUSIONS: Ultrasound-guided pudendal nerve blockade is as accurate as fluoroscopically guided injections when performed by an experienced clinician. However, the former took a longer time to perform.

A low-cost ultrasound phantom of the lumbosacral spine.

BACKGROUND AND OBJECTIVES: This report describes the production of a low-cost ultrasound phantom of the lumbosacral spine. The phantom should be a very useful tool to teach the basic skills for ultrasound-guided procedures of the lumbosacral spine. METHODS: A lumbosacral spine model is secured to the bottom of a microwave-safe container and is immersed in a concentrated gelatin solution. After the gelatin hardens, the model can be used for scanning practice as well as needle placement. The phantom can be recovered after use by melting the gelatin in a microwave to "erase" any needle track marks. RESULTS: A transparent and durable gelatin block is produced. This allows trainees to have direct visual access to the lumbosacral spine model to correlate with the ultrasound images as well as to confirm proper needle placement. Disadvantages of the model include lack of simulated soft tissue structures and an absence of simulated haptic feedback during needle placement. Metamucil can be added to the gelatin to simulate the appearance of soft tissue, although this increases the opacity and thus decreases the visual access of the gelatin. CONCLUSIONS: This teaching tool can provide trainees with an opportunity to familiarize themselves with sonoanatomy of the lumbosacral spine in addition to practicing probe handling techniques and needle placement.

Duloxetine: a review of its pharmacology and use in chronic pain management.

Duloxetine is a serotonin and norepinephrine reuptake inhibitor that possesses antidepressant and pain-relieving properties. Compared with other antidepressants, it has a high affinity for both norepinephrine and serotonin reuptake transporters, which are relatively balanced. Analgesic onset has been observed within the first week of administration in randomized controlled trials and is likely obtained by enhancing the tone of the descending pain inhibition pathways of the central nervous system. Randomized trials have documented significant analgesic effects for managing chronic pain associated with fibromyalgia and diabetic peripheral neuropathic pain. Studies have also suggested that pain associated with major depressive disorder can be reduced with this medication. Modest effects for headache, osteoarthritic pain, and pain secondary to Parkinson disease have also been documented, but data are obtained from single-blinded or open-label trials that require further corroboration with larger randomized studies. Duloxetine has not yet been directly compared with other antidepressants or anticonvulsants for the treatment of pain syndromes.

Case report: retroperitoneoscopic pheochromocytoma removal in an adult with Eisenmenger's syndrome.

PURPOSE: Patients with uncorrected or palliated, complex congenital heart lesions requiring surgery can benefit from laparoscopic techniques, but retroperitoneal insufflation may render them hemodynamically unstable. Alterations in cardiopulmonary physiology during retroperitoneal insufflation have been studied, yet there are no cases detailing this approach in patients with congenital heart lesions. We present a case of a pheochromocytoma removal via retroperitoneoscopy in a patient with a palliated, complex heart lesion. CLINICAL FEATURES: A 28-yr-old woman was admitted for removal of a pheochromocytoma through retroperitoneoscopy. The main feature of her heart disease was a complete atrioventricular canal defect. She eventually developed Eisenmenger's syndrome and became chronically cyanotic. Retroperitoneal insufflation with CO2 gas did not change hemodynamic variables. Significant increases in peak airway pressures were encountered, possibly due to the distending effects of insufflation, or due to increasing the minute ventilation to reduce exogenous CO2. Arterial CO2 remained stable, but a significant increase between end-tidal and arterial levels became apparent with insufflation. Tumour manipulation led to systemic (and possibly pulmonary) hypertension, which exacerbated ventricular dysfunction. This condition resulted in atrioventricular valve regurgitation, as seen on transesophageal echocardiography, and diminished pulmonary blood flow with subsequent desaturation. These changes resolved with antihypertensive medications. The patient's trachea was extubated four hours postoperatively, and she recovered uneventfully. CONCLUSION: Patients with altered cardiopulmonary physiology may tolerate retroperitoneoscopic insufflation with relative hemodynamic stability. Appropriate use of short-acting, vasoactive drugs and aggressive monitoring of PaCO2 and hemodynamic variables is required.