Anesthetic management of a patient undergoing surgery for bilateral pheochromocytoma: a case report.

Pheochromocytomas are rare neuroendocrine tumors. Patients with pheochromocytoma may develop potentially lethal cardiovascular and other complications, especially in the setting of diagnostic or interventional procedures (e.g. upon induction of anesthesia or during surgery). Perioperative management of patients with pheochromocytoma requires detailed knowledge on the pathophysiology and potential complications. This is a case of a 38 year-old, male, with history of bilateral pheochromocyto-, ma, and hypertension secondary to pheochromocytoma, that was scheduled for open bilateral cortical-sparing adrenalectomy under general anesthesia combined with thoracic epidural anesthesia. Although resection of bilateral pheochromocytomas continues being a challenging situation for the anesthetic management, morbidity and mortality can be significantly decreased with preoperative alpha-antagonists treatment, as well as volume restoration, vasoactive drugs, and closely monitoring intra- and postoperatively.

A capillary-mimicking optical tissue phantom for diffuse correlation spectroscopy.

Optical tissue phantoms are necessary for instrument benchmarking and providing a consistent baseline for experiments in various fields of tissue spectroscopy, including diffuse correlation spectroscopy (DCS). To provide the most useful comparisons, a phantom would ideally mimic tissue as closely as possible, including the geometry of static and dynamic scatterers. A branching design that keeps the capillary cross section constant ensures that the same flow velocity is found throughout the phantom while allowing for single input and output fittings to feed all of the capillaries simultaneously. The direction of each capillary is randomized every few millimeters by randomly allocating 2 by 2 "twisting" squares within each layer. These squares swap the locations of four adjacent artificial capillaries either clockwise or counterclockwise. Numerical simulations were used to verify the random walk-like behavior of the capillary paths resulting from this pattern. This is a step toward replicating the randomly varying directionality of actual capillaries. This design was verified by taking DCS measurements at different flow rates of Intralipid through the phantom, demonstrating the effect of the flow rate on the characteristic decay time of the autocorrelation.

Compact dual-mode diffuse optical system for blood perfusion monitoring in a porcine model of microvascular tissue flaps.

In reconstructive surgery, the ability to detect blood flow interruptions to grafted tissue represents a critical step in preventing postsurgical complications. We have developed and pilot tested a compact, fiber-based device that combines two complimentary modalities-diffuse correlation spectroscopy (DCS) and diffuse reflectance spectroscopy-to quantitatively monitor blood perfusion. We present a proof-of-concept study on an in vivo porcine model (n=8). With a controllable arterial blood flow supply, occlusion studies (n=4) were performed on surgically isolated free flaps while the device simultaneously monitored blood flow through the supplying artery as well as flap perfusion from three orientations: the distal side of the flap and two transdermal channels. Further studies featuring long-term monitoring, arterial failure simulations, and venous failure simulations were performed on flaps that had undergone an anastomosis procedure (n=4). Additionally, benchtop verification of the DCS system was performed on liquid flow phantoms. Data revealed relationships between diffuse optical measures and state of occlusion as well as the ability to detect arterial and venous compromise. The compact construction of the device, along with its noninvasive and quantitative nature, would make this technology suitable for clinical translation.

Novel diffuse optics system for continuous tissue viability monitoring - extended recovery in vivo testing in a porcine flap model.

In reconstructive surgery, tissue perfusion/vessel patency is critical to the success of microvascular free tissue flaps. Early detection of flap failure secondary to compromise of vascular perfusion would significantly increase the chances of flap salvage. We have developed a compact, clinically-compatible monitoring system to enable automated, minimally-invasive, continuous, and quantitative assessment of flap viability/perfusion. We tested the system's continuous monitoring capability during extended non-recovery surgery using an in vivo porcine free flap model. Initial results indicated that the system could assess flap viability/perfusion in a quantitative and continuous manner. With proven performance, the compact form constructed with cost-effective components would make this system suitable for clinical translation.

In vivo preclinical verification of a multimodal diffuse reflectance and correlation spectroscopy system for sensing tissue perfusion.

In reconstructive surgery, impeded blood flow in microvascular free flaps due to a compromise in arterial or venous patency secondary to blood clots or vessel spasms can rapidly result in flap failures. Thus, the ability to detect changes in microvascular free flaps is critical. In this paper, we report progress on in vivo pre-clinical testing of a compact, multimodal, fiber-based diffuse correlation and reflectance spectroscopy system designed to quantitatively monitor tissue perfusion in a porcine model's surgically-grafted free flap. We also describe the device's sensitivity to incremental blood flow changes and discuss the prospects for continuous perfusion monitoring in future clinical translational studies.

Design verification of a compact system for detecting tissue perfusion using bimodal diffuse optical technologies.

It is essential to monitor tissue perfusion during and after reconstructive surgery, as restricted blood flow can result in graft failures. Current clinical procedures are insufficient to monitor tissue perfusion, as they are intermittent and often subjective. To address this unmet clinical need, a compact, low-cost, multimodal diffuse correlation spectroscopy and diffuse reflectance spectroscopy system was developed. We verified system performance via tissue phantoms and experimental protocols for rigorous bench testing. Quantitative data analysis methods were employed and tested to enable the extraction of tissue perfusion parameters. This design verification study assures data integrity in future in vivo studies.

[Pachydermoperiostosis (primary hypertrophic osteoarthropathy)]. / Paquidermoperiostosis (osteoartropatia hipertrofica primaria).

Pachydermoperiostosis or primary hypertrophic osteoarthropathy is a rare disease characterized by cutaneous and osteoarthicular involvement. We describe two patients with finger clubbing, watch crystal nails, bones thickenings, arthritis and different grades of skin affection, without other clinical manifestations. Both did not know of having relatives with the same alterations. Radiological studies of the affected areas showed periostosis. Because of normal laboratory results and chest radiography plus the absence of other underlying causes, diagnosis of primary hypertrophic osteoarthropathy was made.

A scalable correlator for multichannel diffuse correlation spectroscopy.

Diffuse correlation spectroscopy (DCS) is a technique which enables powerful and robust non-invasive optical studies of tissue micro-circulation and vascular blood flow. The technique amounts to autocorrelation analysis of coherent photons after their migration through moving scatterers and subsequent collection by single-mode optical fibers. A primary cost driver of DCS instruments are the commercial hardware-based correlators, limiting the proliferation of multi-channel instruments for validation of perfusion analysis as a clinical diagnostic metric. We present the development of a low-cost scalable correlator enabled by microchip-based time-tagging, and a software-based multi-tau data analysis method. We will discuss the capabilities of the instrument as well as the implementation and validation of 2- and 8-channel systems built for live animal and pre-clinical settings.

A compact instrument to measure perfusion of vasculature in transplanted maxillofacial free flaps.

The vascularization and resulting perfusion of transferred tissues are critical to the success of grafts in buried free flap transplantations. To enable long-term clinical monitoring of grafted tissue perfusion during neovascularization and endothelialization, we are developing an implantable instrument for the continuous monitoring of perfusion using diffuse correlation spectroscopy (DCS), and augmented with diffuse reflectance spectroscopy (DRS). This work discusses instrument construction, integration, and preliminary results using a porcine graft model.

Instrument to detect syncope and the onset of shock.

Currently the diagnosis of hemorrhagic shock is essentially clinical, relying on the expertise of nurses and doctors. One of the first measurable physiological changes that marks the onset of hemorrhagic shock is a decrease in capillary blood flow. Diffuse correlation spectroscopy (DCS) quantifies this decrease. DCS collects and analyzes multiply scattered, coherent, near infrared light to assess relative blood flow. This work presents a preliminary study using a DCS instrument with human subjects undergoing a lower body negative pressure (LBNP) protocol. This work builds on previous successful DCS instrumentation development and we believe it represents progress toward understanding how DCS can be used in a clinical setting.

A disposable, flexible skin patch for clinical optical perfusion monitoring at multiple depths.

Stable, relative localization of source and detection fibers is necessary for clinical implementation of quantitative optical perfusion monitoring methods such as diffuse correlation spectroscopy (DCS) and diffuse reflectance spectroscopy (DRS). A flexible and compact device design is presented as a platform for simultaneous monitoring of perfusion at a range of depths, enabled by precise location of optical fibers in a robust and secure adhesive patch. We will discuss preliminary data collected on human subjects in a lower body negative pressure model for hypovolemic shock. These data indicate that this method facilitates simple and stable simultaneous monitoring of perfusion at multiple depths and within multiple physiological compartments.

Quantitative and functional interrogation of parent-of-origin allelic expression biases in the brain.

The maternal and paternal genomes play different roles in mammalian brains as a result of genomic imprinting, an epigenetic regulation leading to differential expression of the parental alleles of some genes. Here we investigate genomic imprinting in the cerebellum using a newly developed Bayesian statistical model that provides unprecedented transcript-level resolution. We uncover 160 imprinted transcripts, including 41 novel and independently validated imprinted genes. Strikingly, many genes exhibit parentally biased--rather than monoallelic--expression, with different magnitudes according to age, organ, and brain region. Developmental changes in parental bias and overall gene expression are strongly correlated, suggesting combined roles in regulating gene dosage. Finally, brain-specific deletion of the paternal, but not maternal, allele of the paternally-biased Bcl-x, (Bcl2l1) results in loss of specific neuron types, supporting the functional significance of parental biases. These findings reveal the remarkable complexity of genomic imprinting, with important implications for understanding the normal and diseased brain.

Paquidermoperiostosis (osteoartropatia hipertrofica primaria) / Pachydermoperiostosis (primary hypertrophic osteoarthropathy)

La paquidermoperiostosis u osteoartropatía hipertrófica primaria es una rara enfermedadcaracterizada por compromiso cutáneo y osteoarticular. Comunicamos dos casos que presentabanhipocratismo digital, uñas en vidrio de reloj, agrandamiento óseo, tumefacción articular y diferentes grados deafectación cutánea, sin otros hallazgos clínicos relevantes. Ambos desconocían antecedentes familiares similares.El estudio radiográfico de las zonas comprometidas mostró periostosis. Con resultados de laboratorio yradiografía de tórax normales, y ausencia de evidencia clínica de otra enfermedad subyacente, se realizó diagnósticode osteoartropatía hipertrófica primaria.

Pachydermoperiostosis orprimary hypertrophic osteoarthropathy is a rare disease characterized by cutaneous and osteoarthicularinvolvement. We describe two patients with finger clubbing, watch crystal nails, bones thickenings,arthritis and different grades of skin affection, without other clinical manifestations. Both did not know of havingrelatives with the same alterations. Radiological studies of the affected areas showed periostosis. Because ofnormal laboratory results and chest radiography plus the absence of other underlying causes, diagnosis of primaryhypertrophic osteoarthropathy was made.