Evaluating a unique enhanced recovery protocol in laparoscopic donor nephrectomy: A single center experience.

INTRODUCTION: Enhanced recovery after surgery (ERAS) protocols have been associated with a reduction in opioid consumption and a hastening in recovery in abdominal surgery. However, their impact on laparoscopic donor nephrectomy (LDN) has not been fully elucidated. The aim of this study is to evaluate opioid consumption and other relevant outcome measures before and after implementation of a unique LDN ERAS protocol. METHODS: 244 LDN patients were included in this retrospective cohort study. Forty-six underwent LDN prior to implementation of ERAS, whereas 198 patients received ERAS perioperative care. The primary outcome was daily oral morphine equivalent (OME) consumption averaged over the entire postoperative stay. Due to removal of preoperative oral morphine from the protocol partway through the study period, the ERAS group was further subdivided into morphine recipients and non-recipients for subgroup analysis. Secondary outcomes included the incidence of postoperative nausea and vomiting (PONV), length of stay, pain scores, and other relevant measures. RESULTS: ERAS donors consumed significantly fewer average daily OMEs than Pre-ERAS donors (21.5 vs. 37.6, respectively; p < .0001). There were no statistically significant differences in OME consumption between morphine recipients and non-recipients. The ERAS group experienced less PONV (44.4% requiring one or more rescue antiemetic postoperatively, vs. 60.9% of Pre-ERAS donors; p = .008). CONCLUSIONS: A protocol pairing lidocaine and ketamine with a comprehensive approach to preoperative PO intake, premedication, intraoperative fluid management and postoperative pain control is associated with reduced opioid consumption in LDN.

Perioperative clinical utility of myocardial deformation imaging: a narrative review.

Preoperative cardiac function is an important predictor of postoperative outcomes. Patients with heart failure are at higher risk of perioperative morbidity and mortality. Left ventricular ejection fraction, derived by standard echocardiography, is most frequently used to assess cardiac function in the intraoperative and postoperative periods. Myocardial strain analysis, a measurement of myocardial deformation, can provide additional information to left venricular eject fraction estimation. Here, we provide an overview of myocardial strain and different methods used to evaluate strain, including speckle tracking echocardiography. Speckle tracking echocardiography is an imaging modality that can analyse and track small segments of the myocardium, which provides greater detail for assessing global and regional cardiac motion and function. We further review the literature to illustrate the value of speckle tracking echocardiography-derived myocardial strain in describing cardiac function and its association with adverse surgical outcomes in the perioperative period, including low cardiac output states, need for inotropic support, postoperative arrhythmias, subclinical myocardial ischaemia, and length of hospital stay.

In Vivo Measurement of Rotator Cuff Tear Tension: Medial Versus Lateral Footprint Position.

We conducted a study to evaluate in vivo tension applied to the rotator cuff tendon positioned at the medial versus lateral footprint during arthroscopic rotator cuff repair. We evaluated 20 consecutive patients who underwent arthroscopic rotator cuff repair. During repair, a grasper was inserted through a lateral portal, and a digital weigh scale was attached. The tendon was grasped and translated to the medial footprint, and tension recorded. After a relaxation period, the tendon edge was translated to the lateral footprint, and tension recorded. Mean (SD) tension was 0.41 (0.33) pound when tendons were positioned at the medial footprint and 2.21 (1.20) pounds when they were positioned at the lateral footprint, representing a 5.4-fold difference (P < .0001). For smaller tears (≤ 20 mm anterior-posterior), 7.6 times less tension was applied to the tendons when pulled to the medial versus lateral footprint. For larger tears, 4.1 times less tension was applied to the tendons when pulled to the medial versus lateral footprint. This study demonstrated a significant, 5.4-fold increase in tension when the tendon edge was reduced to the lateral as opposed to the medial footprint in vivo.

WESTPA: an interoperable, highly scalable software package for weighted ensemble simulation and analysis.

The weighted ensemble (WE) path sampling approach orchestrates an ensemble of parallel calculations with intermittent communication to enhance the sampling of rare events, such as molecular associations or conformational changes in proteins or peptides. Trajectories are replicated and pruned in a way that focuses computational effort on underexplored regions of configuration space while maintaining rigorous kinetics. To enable the simulation of rare events at any scale (e.g., atomistic, cellular), we have developed an open-source, interoperable, and highly scalable software package for the execution and analysis of WE simulations: WESTPA (The Weighted Ensemble Simulation Toolkit with Parallelization and Analysis). WESTPA scales to thousands of CPU cores and includes a suite of analysis tools that have been implemented in a massively parallel fashion. The software has been designed to interface conveniently with any dynamics engine and has already been used with a variety of molecular dynamics (e.g., GROMACS, NAMD, OpenMM, AMBER) and cell-modeling packages (e.g., BioNetGen, MCell). WESTPA has been in production use for over a year, and its utility has been demonstrated for a broad set of problems, ranging from atomically detailed host­guest associations to nonspatial chemical kinetics of cellular signaling networks. The following describes the design and features of WESTPA, including the facilities it provides for running WE simulations and storing and analyzing WE simulation data, as well as examples of input and output.

"Hospital-corner repair" for shoulder instability.

Most shoulder instability repairs are performed with single-loaded suture anchors. Recent reports have shown that there is increased stress on both the glenoid labrum and suture anchor when sutures from single-loaded anchors are passed through the capsule and labrum. This report describes a novel technique for shoulder instability repair using double-loaded suture anchors in the glenoid. The first primary stitch is passed through the labrum only and then tied, shifting the tissue superiorly. The second stitch is passed inferiorly through the patulous capsule in addition to the labrum with a pinch-tuck technique. This technique distributes the tension on the labral repair and creates a fold to protect and shield the primary labral repair. Just as flat sheets are folded and tucked underneath a mattress to form a "hospital corner," this procedure applies a similar principle to the labrum and capsule of the shoulder. This technique is applicable for any type of shoulder instability repair, including Bankart lesions, posterior labral tears, and multidirectional instability, that requires the use of suture anchors.

SGLT1, a novel cardiac glucose transporter, mediates increased glucose uptake in PRKAG2 cardiomyopathy.

Human mutations in the gene PRKAG2 encoding the gamma2 subunit of AMP-activated protein kinase (AMPK) cause a glycogen storage cardiomyopathy. Transgenic mice (TG(T400N)) with the human T400N mutation exhibit inappropriate activation of AMPK and consequent glycogen storage in the heart. Although increased glucose uptake and activation of glycogen synthesis have been documented in PRKAG2 cardiomyopathy, the mechanism of increased glucose uptake has been uncertain. Wildtype (WT), TG(T400N), and TG(alpha2DN) (carrying a dominant negative, kinase dead alpha2 catalytic subunit of AMPK) mice were studied at ages 2-8 weeks. Cardiac mRNA expression of sodium-dependent glucose transporter 1 (SGLT1), but not facilitated-diffusion glucose transporter 1 (GLUT1) or GLUT4, was increased approximately 5- to 7-fold in TG(T400N) mice relative to WT. SGLT1 protein was similarly increased at the cardiac myocyte sarcolemma in TG(T400N) mice. Phlorizin, a specific SGLT1 inhibitor, attenuated cardiac glucose uptake in TG(T400N) mice by approximately 40%, but not in WT mice. Chronic phlorizin treatment reduced cardiac glycogen content by approximately 25% in TG(T400N) mice. AICAR, an AMPK activator, increased cardiac SGLT1 mRNA expression approximately 3-fold in WT mice. Relative to TG(T400N) mice, double transgenic (TG(T400N)/TG(alpha2DN)) mice had decreased ( approximately 50%) cardiac glucose uptake and decreased (approximately 70%) cardiac SGLT1 expression. TG(T400N) hearts had increased binding activity of the transcription factors HNF-1 and Sp1 to the promoter of the gene encoding SGLT1. Our data suggest that upregulation of cardiac SGLT1 is responsible for increased cardiac glucose uptake in the TG(T400N) mouse. Increased AMPK activity leads to upregulation of SGLT1, which in turn mediates increased cardiac glucose uptake.

Subtalar distraction arthrodesis using interpositional frozen structural allograft.

BACKGROUND: Subtalar bone-block distraction arthrodesis using structural autograft carries the risk of donor site morbidity. Recent reports suggest that structural allograft may be an attractive alternative to structural autograft in subtalar arthrodesis. This prospective study analyzes subtalar distraction arthrodesis using interpositional structural allograft. MATERIALS AND METHODS: Between 2000 and 2006, 22 patients (24 feet; mean age, 45.6 years) underwent subtalar arthrodesis with interpositional fresh-frozen femoral head structural allograft. Indications included subtalar arthrosis, loss of heel height, and anterior ankle impingement. Clinical outcome was assessed using the AOFAS ankle-hindfoot scoring system. Time to union was determined by previously reported clinical findings and radiographic evidence for bridging trabeculation between host bone and structural allograft. RESULTS: Mean followup was 35.8 months for 20 patients (21 feet) available for followup evaluation. Union was achieved in 19 of 21 patients (90%) at a mean of 15.5 (range, 11 to 19) weeks. Mean AOFAS hindfoot score improved from 21 to 71 points (p < 0.05). Radiographic analysis suggested significant (p < 0.05) improvement in all measurements. Complications included nonunion (2), varus malalignment (1), persistent subfibular impingement (1), sural neuralgia (1), and prominent hardware (2). Both patients with nonunions had avascular bone at the arthrodesis site and used tobacco products. CONCLUSION: This study supports recent publications that subtalar arthrodesis using interpositional structural allograft can have a favorable outcome. Our clinical and radiographic results suggest that restoration of hindfoot function and dimensions with structural allograft are comparable to results reported for the same procedure using structural autograft. LEVEL OF EVIDENCE: Level IV, prospective case series.

A quantitative comparison of surgical approaches for posterolateral osteochondral lesions of the talus.

BACKGROUND: Exposure of the posterolateral talar dome for osteochondral autograft transfer can be challenging. The purpose of this study is to compare surgical exposures for perpendicular access to the posterolateral talar dome using osteochondral transfer instrumentation. MATERIALS AND METHODS: Five surgical approaches were performed on each of eight cadaveric ankles. The sequence was: (1) Anterolateral arthrotomy with ATFL release, (2) Anterolateral tibial osteotomy, (3) Fibular osteotomy with ATFL intact, (4) Fibular osteotomy with ATFL release, and (5) Fibular osteotomy with ATFL/CFL release. (ATFL repaired between 1 and 2). While maintaining the orientation of the harvester perpendicular to the talar dome articular surface, osteochondral plugs were harvested as far posteriorly as possible using a 6-mm harvester. Distances from the anterior talar articular surface to the posterior aspect of the recipient site were measured. Statistical analysis used ANOVA and Fisher post hoc tests. RESULTS: Average AP exposure (mm) and percentage of AP talar dome dimensions exposed: (1) Anterolateral arthrotomy with ATFL release: 21.2 mm (43.3%), (2) Anterolateral tibial osteotomy: 33.7 mm (68.5%), (3) Fibular osteotomy(ATFL intact): 43.2 mm (87.8%), (4) Fibular osteotomy with ATFL release: 44.9 mm (91.2%), and (5) Fibular osteotomy with ATFL/CFL release: 46.6 mm (94.6%). All osteotomies provided greater exposure than anterolateral arthrotomy with ATFL release (p < 0.0001). A significant difference was obtained between each of the fibular osteotomies and tibial osteotomy (p < 0.0001). Differences between the fibular osteotomy approaches (3 to 5) were not significant. CONCLUSION: Fibular osteotomy provides the greatest perpendicular exposure to the posterolateral talar dome. Anterolateral tibial osteotomy provides greater exposure than arthrotomy alone. CLINICAL RELEVANCE: This study provides a guide for surgical exposures to the posterolateral talar dome for osteochondral autograft transfer.

A user-friendly interface for surgeons to create haptic effects in medical simulation.

Haptics, namely the sense of touch, has been playing an important role in medical simulation. However, most medical practitioners, who are best suited to create the training environments, do not have the engineering expertise necessary for programming a haptic environment. We propose a user-friendly interface that allows surgeons to arbitrarily select regions on a 3D model of an organ, similar to "painting-by-numbers", and tune the haptic properties of each region in an intuitive way. The selected region and tuned haptic properties are recorded in a lookup table in real-time. The proposed user interface is assessed by comparing the haptic effects of a tumor on a virtual liver created by a number of surgeons.

Bottom-up determination of air-sea momentum exchange under a major tropical cyclone.

As a result of increasing frequency and intensity of tropical cyclones, an accurate forecasting of cyclone evolution and ocean response is becoming even more important to reduce threats to lives and property in coastal regions. To improve predictions, accurate evaluation of the air-sea momentum exchange is required. Using current observations recorded during a major tropical cyclone, we have estimated this momentum transfer from the ocean side of the air-sea interface, and we discuss it in terms of the drag coefficient. For winds between 20 and 48 meters per second, this coefficient initially increases and peaks at winds of about 32 meters per second before decreasing.

Toward a systems- and control-oriented agent framework.

This paper develops a systems- and control-oriented intelligent agent framework called the hybrid intelligent control agent (HICA), as well as its composition into specific kinds of multiagent systems. HICA is essentially developed around a hybrid control system core so that knowledge-based planning and coordination can be integrated with verified hybrid control primitives to achieve the coordinated control of multiple multimode dynamical systems. The scheme is applied to the control of teams of unmanned air and ground vehicles engaged in a pursuit-evasion war game. Results are demonstrated in simulation.

Extreme waves under Hurricane Ivan.

Hurricane Ivan, a category 4 storm, passed directly over six wave-tide gauges deployed by the Naval Research Laboratory on the outer continental shelf in the northeastern Gulf of Mexico. Waves were observed with significant wave heights reaching 17.9 meters and maximum crest-to-trough individual wave heights of 27.7 meters (91 feet). Analysis suggests that significant wave heights likely surpassed 21 meters (69 feet) and that maximum crest-to-trough individual wave heights exceeded 40 meters (132 feet) near the eyewall.

Influence of oxygen on the proliferation and metabolism of adipose derived adult stem cells.

Articular cartilage is an avascular connective tissue that exhibits little intrinsic capacity for repair. Articular cartilage exists in a reduced oxygen ( approximately 5%) environment in vivo; therefore, oxygen tension may be an important factor that regulates the metabolism of chondrocyte progenitors. A number of recent studies have developed tissue engineering approaches for promoting cartilage repair using undifferentiated progenitor cells seeded on biomaterial scaffolds, but little is known about how oxygen might influence these engineered tissues. Human adipose-derived adult stem (hADAS) cells isolated from the stroma of subcutaneous fat were suspended in alginate beads and cultured in control or chondrogenic media in either low oxygen (5%) or atmospheric oxygen tension (20%) for up to 14 days. Under chondrogenic conditions, low oxygen tension significantly inhibited the proliferation of hADAS cells, but induced a two-fold increase in the rate of protein synthesis and a three-fold increase in total collagen synthesis. Low oxygen tension also increased glycosaminoglycan synthesis at certain timepoints. Immunohistochemical analysis showed significant production of cartilage-associated matrix molecules, including collagen type II and chondroitin-4-sulfate. These findings suggest oxygen tension may play an important role in regulating the proliferation and metabolism of hADAS cells as they undergo chondrogenesis, and the exogenous control of oxygen tension may provide a means of increasing the overall accumulation of matrix macromolecules in tissue-engineered cartilage.