Distal subsartorial compartment block of the saphenous nerve - A dissection study and a patient case series.

STUDY OBJECTIVE: A saphenous nerve block is an important tool for analgesia after foot and ankle surgery. The conventional midthigh approach to saphenous nerve block in the femoral triangle may impede ambulation by impairing quadriceps motor function. PRIMARY OBJECTIVE: Developing a selective saphenous nerve block targeting the nerve distal to its emergence from the adductor canal in the subsartorial compartment. DESIGN: This study consists of A) a dissection study and B) Data from a clinical case series. SETTING: A) Medical University of Innsbruck, Austria (dissection of 15 cadaver sides) and. B) Aarhus University Hospital, Denmark (5 patients). INTERVENTIONS: A) Five mL of methylene blue was injected into the subsartorial compartment distal to the intersection of the saphenous nerve and the tendon of the adductor magnus guided by ultrasound. B) Five patients undergoing major hindfoot and ankle surgery had a subsartorial compartment block with 10 mL of local anesthetic in addition to a popliteal sciatic nerve block. MEASUREMENT: A) The frequencies of staining the saphenous and medial vastus nerves. B) Assessment of postoperative pain by NRS score (0-10) and success rate of saphenous nerve block by presence of cutaneous anesthesia in the anteromedial lower leg, and motor impairment by ability to ambulate. MAIN RESULTS: A) The saphenous nerve was stained in 15/15 cadaver sides. A terminal branch of the medial vastus nerve was stained in 2/15 cadaver sides. B) All patients were fully able to ambulate without support. No patients had any post-surgical pain from the anteromedial aspect of the ankle and foot (NRS score 0). The success rate of saphenous nerve block was 100%. CONCLUSION: The saphenous nerve can be targeted in the subsartorial compartment distal to the intersection of the nerve and the tendon of the adductor magnus. The subsartorial compartment block provided efficient analgesia without quadriceps motor impairment.

The anterior branch of the medial femoral cutaneous nerve innervates the anterior knee: a randomized volunteer trial.

BACKGROUND: The midline skin incision for total knee arthroplasty may be an important generator of chronic neuropathic pain. The incision is innervated by the medial femoral cutaneous nerve (MFCN), the intermediate femoral cutaneous nerves (IFCN) and the infrapatellar branch from the saphenous nerve. The MFCN divides into an anterior (MFCN-A) and a posterior branch (MFCN-P). The primary aim was to compare the areas anesthesized by MFCN-A versus MFCN-P block for coverage of the incision. METHODS: Nineteen healthy volunteers had IFCN and saphenous nerve blocks. The subgroup of volunteers with a non-anesthetized gap between the areas anesthetized by the saphenous and the IFCN blocks was defined as the study group for the primary outcome. Subsequently selective MFCN-A block and MFCN block (MFCN-A + MFCN-P) were performed to investigate the contributions from MFCN-A and MFCN-P to the innervation of the midline incision. All assessments were performed blinded. RESULTS: Ten out of 19 volunteers had a non-anesthetized gap. Nine out of these 10 volunteers had coverage of the non-anesthetized gap after selective anesthesia of the MFCN-A, whereas anesthesia of the MFCN-P did not contribute to coverage of the gap in any of the 10 volunteers. CONCLUSIONS: In half of the cases, a gap of non-anesthetized skin was present on the surgical midline incision after anesthesia of the saphenous nerve and the IFCN. This gap was covered by selective anesthesia of the MFCN-A without contribution from MFCN-P. The selective MFCN-A block may be relevant for diagnosis and interventional management of neuropathic pain due to injury of MFCN-A.

Probabilistic Models with Deep Neural Networks.

Recent advances in statistical inference have significantly expanded the toolbox of probabilistic modeling. Historically, probabilistic modeling has been constrained to very restricted model classes, where exact or approximate probabilistic inference is feasible. However, developments in variational inference, a general form of approximate probabilistic inference that originated in statistical physics, have enabled probabilistic modeling to overcome these limitations: (i) Approximate probabilistic inference is now possible over a broad class of probabilistic models containing a large number of parameters, and (ii) scalable inference methods based on stochastic gradient descent and distributed computing engines allow probabilistic modeling to be applied to massive data sets. One important practical consequence of these advances is the possibility to include deep neural networks within probabilistic models, thereby capturing complex non-linear stochastic relationships between the random variables. These advances, in conjunction with the release of novel probabilistic modeling toolboxes, have greatly expanded the scope of applications of probabilistic models, and allowed the models to take advantage of the recent strides made by the deep learning community. In this paper, we provide an overview of the main concepts, methods, and tools needed to use deep neural networks within a probabilistic modeling framework.

An iliopsoas plane block does not cause motor blockade-A blinded randomized volunteer trial.

BACKGROUND: A femoral nerve block relieves pain after total hip arthroplasty, but its use is controversial due to motor paralysis accompanied by an increased risk of fall. Assumedly, the iliopsoas plane block (IPB) targets the hip articular branches of the femoral nerve without motor blockade. However, this has only been indicated in a cadaver study. Therefore, we designed this volunteer study. METHODS: Twenty healthy volunteers were randomly allocated to blinded paired active vs. sham IPB (5 mL lidocaine 18 mg/mL with epinephrine vs saline). The primary outcome was reduction of maximal force of knee extension after IPB compared to baseline. Secondary outcomes included reduction of maximal force of hip adduction, and the pattern of injectate spread assessed with magnetic resonance imaging. RESULTS: Mean (confidence interval) change of maximal force of knee extension from baseline to after IPB was -9.7 N (-22, 3.0) (P = .12) (n = 14). The injectate was consistently observed in an anatomically well-defined closed fascial compartment between the intra- and extra-pelvic components of the iliopsoas muscle anterior to the hip joint. CONCLUSION: We observed no significant reduction of maximal force of knee extension after an IPB. The injectate was contained in a fascial compartment previously shown to contain all sensory branches from the femoral nerve to the hip joint. The clinical consequence of selective anesthesia of all sensory femoral nerve branches from the hip could be a reduced risk of fall compared to a traditional femoral nerve block. Registration of Trial: The trial was prospectively registered in EudraCT (Reference: 2018-000089-12, https://www.clinicaltrialsregister.eu/ctr-search/search?query=2018-000089-12).

Are single-injection erector spinae plane block and multiple-injection costotransverse block equivalent to thoracic paravertebral block?

BACKGROUND: Thoracic paravertebral block (TPVB) is considered the gold standard for hemithoracic regional anaesthesia. Erector spinae plane block (ESPB) is a new posterior thoracic wall block. Multiple-injection costotransverse block (MICB) mimics TPVB but with injection points within the thoracic intertransverse tissue complex and posterior to the superior costotransverse ligament. We aimed to compare the spread of injectate into the thoracic paravertebral space (TPVS) resulting from single-injection ESPB and MICB, respectively, with TPVB. METHODS: Ten soft-embalmed cadavers were utilised. In five cadavers, the right hemithorax was randomly allocated either to ultrasound-guided single-injection ESPB or single-injection TPVB; vice versa on the other side. In another five cadavers, the right hemithorax was randomly allocated either to ultrasound-guided MICB or multiple-injection TPVB. About 20 mL of dye was injected in each hemithorax with all techniques. RESULTS: With TPVB, the dye was consistently present in the TPVS with concomitant epidural spread in the majority of cases. The injectate spread into the TPVS with ESPB (60%) and MICB (100%). MICB consistently stained the ventral rami (T1-7), communicating rami and thoracic sympathetic trunk without epidural spread. Dissection after MICB revealed dye spread into the TPVS via the costotransverse foramina and along the dorsal branches of the posterior intercostal veins. CONCLUSIONS: Consistent spread of dye into the TPVS colouring the ventral rami, the communicating rami, and the sympathetic trunk was observed with MICB; in this respect equivalent to TPVB. ESPB exhibited only partial success and was not equivalent to TPVB. No epidural spread was found with neither MICB nor ESPB.

Cutaneous anaesthesia of hip surgery incisions with iliohypogastric and subcostal nerve blockade: A randomised trial.

BACKGROUND: Cutaneous nerve blockade may improve analgesia after hip surgery. Anaesthesia after the lateral femoral cutaneous (LFC) nerve block is too distal for complete coverage of most hip surgery incisions, which requires additional anaesthesia of the adjacent, proximal area. The transversalis fascia plane (TFP) block potentially anaesthetises the iliohypogastric and subcostal nerves. The primary aim of the present study was to investigate, if the TFP block provides cutaneous anaesthesia adjacent to the LFC nerve block. METHODS: Active vs placebo TFP blocks were compared in a paired randomised controlled trial (RCT) in 20 volunteers, who all had bilateral LFC nerve blocks. The day preceding the RCT, the area anaesthetised by a novel selective ultrasound guided subcostal nerve block was identified bilaterally in order to assess the contribution of the subcostal nerve to the area anaesthesia by the TFP block. RESULTS: Anaesthesia of the lateral hip region after TFP block was 80%. The cutaneous anaesthesia after active TFP block was in continuity with the LFC nerve block in 65%. Combined TFP and LFC nerve blockade significantly increased the coverage of hip surgery incisions compared to LFC nerve block alone. The success rate of blocking the subcostal nerve was 50% with the TFP block. CONCLUSION: The TFP block anaesthetises the skin proximal to the LFC nerve block by anaesthetising the iliohypogastric and subcostal nerves. TFP block as a supplement to LFC nerve block improves the coverage of the proximal surgical incisions used for hip surgery.

The Lateral Femoral Cutaneous Nerve: Description of the Sensory Territory and a Novel Ultrasound-Guided Nerve Block Technique.

BACKGROUND AND OBJECTIVES: Nerve blockade of the lateral femoral cutaneous (LFC) nerve provides some analgesia after hip surgery. However, knowledge is lacking about the extent of the cutaneous area anesthetized by established LFC nerve block techniques, as well as the success rate of anesthetic coverage of various surgical incisions. Nerve block techniques that rely on ultrasonographic identification of the LFC nerve distal to the inguinal ligament can be technically challenging. Furthermore, the branching of the LFC nerve is variable, and it is unknown if proximal LFC nerve branches are anesthetized using the current techniques. The primary aim of this study was to investigate a novel ultrasound-guided LFC nerve block technique based on injection into the fat-filled flat tunnel (FFFT), which is a duplicature of the fascia lata between the sartorius and the tensor fasciae latae muscle, in order to assess the success rate of anesthetizing the proximal LFC nerve branches and covering of the different surgical incisions used for hip surgery. METHODS: First, a cadaveric study was conducted in order to identify an FFFT injection technique that would provide adequate injectate spread to the proximal LFC nerve branches. Second, a clinical study was conducted in a group of 20 healthy volunteers over 2 consecutive days. On trial day 1, successful complete anesthesia of the LFC nerve was defined by performing a suprainguinal fascia iliaca block bilaterally in each subject. On trial day 2, a triple-blind randomized controlled trial compared the effect of the novel ultrasound-guided LFC nerve block technique for bupivacaine versus placebo. The primary end point was the success rate of anesthesia of the proximal cutaneous area innervated by the LFC nerve for the FFFT injection with bupivacaine versus placebo. RESULTS: Adequate spread of injectate to the proximal LFC nerve branches in cadavers was obtained by injecting 10 mL with dynamic needle-tip tracking in the FFFT. Application of this technique in the randomized controlled trial provided anesthesia of the lateral thigh with a success rate of 95% (95% confidence interval, 73.9%-99.8%) for the active side and 0% for placebo (P < 0.001). The proximal branches were anesthetized with a success rate of 68% (95% confidence interval, 43.4%-87.4%) on the active side. The proximal extent of the anesthetized cutaneous area was on average 7.9 cm distal to the greater trochanter. CONCLUSIONS: This novel LFC nerve block technique is easy and quick and reliably produces anesthesia of the lateral thigh. The greater trochanter is rarely included in the area of anesthesia, which reduces the coverage of each specific surgical incision. The success rate of 68% in anesthetizing the proximal nerve branches must be further evaluated by future research.

A Cadaveric Study of Ultrasound-Guided Subpectineal Injectate Spread Around the Obturator Nerve and Its Hip Articular Branches.

BACKGROUND AND OBJECTIVES: The femoral and obturator nerves are assumed to account for the primary nociceptive innervation of the hip joint capsule. The fascia iliaca compartment block and the so-called 3-in-1-block have been used in patients with hip fracture based on a presumption that local anesthetic spreads to anesthetize both the femoral and the obturator nerves. Evidence demonstrates that this presumption is unfounded, and knowledge about the analgesic effect of obturator nerve blockade in hip fracture patients presurgically is thus nonexistent. The objectives of this cadaveric study were to investigate the proximal spread of the injectate resulting from the administration of an ultrasound-guided obturator nerve block and to evaluate the spread around the obturator nerve branches to the hip joint capsule. METHODS: Fifteen milliliters of methylene blue was injected into the interfascial plane between the pectineus and external obturator muscles in 7 adult cadavers. The spread of the injectate into the obturator canal and around the obturator and accessory obturator nerve branches to the hip joint was evaluated by subsequent dissection. RESULTS: The injected dye spread into the obturator canal and colored all obturator branches to the hip joint capsule in all 14 sides. Furthermore, the accessory obturator nerve was present in 3 sides (21%), and the nerve and its branches to the hip joint capsule were colored in all cases. CONCLUSIONS: In cadavers, injection of 15 mL of methylene blue into the interfascial plane between the pectineus and the external obturator muscle effectively spreads proximally to reach the obturator canal, as well as the obturator nerve branches to the hip joint capsule and the accessory obturator nerve.

Ultrasound guidance improves a continuous popliteal sciatic nerve block when compared with nerve stimulation.

BACKGROUND AND OBJECTIVES: Continuous sciatic nerve blockade at the popliteal level effectively alleviates postoperative pain after major foot and ankle surgery. No randomized controlled trials have previously compared the success rate of continuous sciatic nerve sensory blockade between ultrasound and nerve stimulation guidance. In the current study, we tested the hypothesis that ultrasound-guided catheter placement improves the success rate of continuous sciatic nerve sensory blockade compared with catheter placement with nerve stimulation guidance. METHODS: After research ethics committee approval and informed consent, 100 patients scheduled for elective major foot and ankle surgery were randomly allocated to popliteal catheter placement either with ultrasound or nerve stimulation guidance. The primary outcome was the success rate of sensory block the first 48 postoperative hours. Successful sensory blockade was defined as sensory loss in both the tibial and common peroneal nerve territories at 1, 6, 24, and 48 hrs postoperatively. RESULTS: The ultrasound group had significantly higher success rate of sensory block compared with the nerve stimulation group (94% versus 79%, P=0.03). Ultrasound compared with nerve stimulation guidance also entails reduced morphine consumption (median of 18 mg [range, 0-159 mg] versus 34 mg [range, 0-152 mg], respectively, P=0.02), fewer needle passes (median of 1 [range, 1-6] versus 2 [range, 1-10], respectively, P=0.0005), and greater patient satisfaction (median numeric rating scale 9 [range, 5-10] versus 8 [range, 3-10)] respectively, P=0.0006) during catheter placement. CONCLUSION: Ultrasound guidance used for sciatic catheter placement improves the success rate of sensory block, number of needle passes, patient satisfaction during catheter placement, and morphine consumption compared with nerve stimulation guidance.

Epicardial mapping of ventricular fibrillation over the posterior descending artery and left posterior papillary muscle of the swine heart.

BACKGROUND: Recent studies suggest that during ventricular fibrillation (VF) epicardial vessels may be a site of conduction block and the posterior papillary muscle (PPM) in the left ventricle (LV) may be the location of a "mother rotor." The goal of this study was to obtain evidence to support or refute these possibilities. METHODS: Epicardial activation over the posterior LV and right ventricle (RV) was mapped during the first 20 s of electrically induced VF in six open-chest pigs with a 504 electrode plaque covering a 20 cm(2) area centered over the posterior descending artery (PDA). RESULTS: The locations of epicardial breakthrough as well as reentry clustered in time and space during VF. Spatially, reentry occurred significantly more frequently over the LV than the RV in all 48 episodes, and breakthrough clustered near the PPM (p < 0.001). Significant temporal clustering occurred in 79% of breakthrough episodes and 100% of reentry episodes. These temporal clusters occurred at different times so that there was significantly less breakthrough when reentry was present (p < 0.0001). Conduction block occurred significantly more frequently near the PDA than elsewhere. CONCLUSIONS: The PDA is a site of epicardial block which may contribute to VF maintenance. Epicardial breakthrough clusters near the PPM. Reentry also clusters in space but at a separate site. The fact that breakthrough and reentry cluster at different locations and at different times supports the possibility of a drifting filament at the PPM so that at times reentry is present on the surface but at other times the reentrant wavefront breaks through to the epicardium.

Nonischemic cardiomyopathy associated with autoimmune polyglandular syndrome type II.

OBJECTIVE: To report a case of nonischemic cardiomyopathy associated with autoimmune polyglandular syndrome type II (APS-II). METHODS: We describe our patient's clinical features, evaluation, and outcome. In addition, a literature review of cardiomyopathy associated with polyendocrinopathy syndromes is presented. RESULTS: The component disorders of APS-II are Addison's disease in combination with either autoimmune thyroid disease or type 1 (insulin-dependent) diabetes. Although numerous other autoimmune conditions have been reported in conjunction with APS-II, cardiomyopathy has not been previously described as part of this syndrome. The current patient was a 32-year-old man who, during a 5-year period, was diagnosed as having type 1 diabetes mellitus, Crohn's disease, and Addison's disease. In 2001, he presented with severe heart failure that progressed rapidly and eventually necessitated cardiac transplantation. CONCLUSION: Although autoimmune cardiomyopathy has been associated with other autoimmune disorders, to our knowledge this is the first reported case of cardiomyopathy in association with an autoimmune polyglandular syndrome. Patients with this syndrome should undergo clinical evaluation for heart failure.

Atrial fibrillation after pulmonary transplant.

BACKGROUND: Although atrial fibrillation or flutter (AF) is thought to occur commonly after pulmonary transplantation, little is known about the epidemiology, risk factors, or clinical significance of arrhythmia in this population. The aim of the current study was to determine the incidence, clinical predictors, and associated morbidity of AF after lung transplant. METHODS: The records of 200 consecutive adult patients who underwent lung transplantation at a single institution from August 1998 to June 2002 were studied. Multivariate logistic regression analysis was performed to define the predictors for posttransplant AF. RESULTS: Indications for transplant included COPD in 43%, cystic fibrosis in 18%, and idiopathic pulmonary fibrosis (IPF) in 17%. The transplants were bilateral (79%) or single lung (21%). The mean age of the patients was 50 years (range, 19 to 66 years; median, 54 years). Postoperative AF within 14 days of transplant occurred in 78 patients (39%), with a mean onset of 3.8 +/- 3.0 days (+/- SD). Significant predictors of AF were as follows: age >or= 50 years (odds ratio [OR], 2.1; p = 0.01), IPF (OR, 2.3; p = 0.03), existing coronary disease (OR, 2.0; p = 0.009), enlarged left atrium (LA) on echocardiography (OR, 3.9; p = 0.05), and number of postoperative vasopressors (OR, 1.5; p = 0.03). Patients with AF had longer hospital stays (32.4 +/- 60.0 days vs 17.5 +/- 24.1 days, p = 0.04), were more likely to undergo tracheostomy (OR, 3.6; p = 0.0003), and had more in-hospital deaths (OR, 5.7; p = 0.0005) than patients without AF. CONCLUSIONS: AF is a frequent complication after lung transplant. Advanced age, IPF, known coronary disease, enlarged LA, and use of postoperative vasopressors increase the risk for developing AF. The development of posttransplant AF is associated with significantly prolonged hospital stay and increased mortality. Prospective studies designed to prevent posttransplant AF are needed to clarify the extent to which AF impacts on posttransplant outcomes.

Latent variable discovery in classification models.

The naive Bayes model makes the often unrealistic assumption that the feature variables are mutually independent given the class variable. We interpret a violation of this assumption as an indication of the presence of latent variables, and we show how latent variables can be detected. Latent variable discovery is interesting, especially for medical applications, because it can lead to a better understanding of application domains. It can also improve classification accuracy and boost user confidence in classification models.