Ferromagnetic Heating for Vessel Sealing and Division: Utility and Comparative Study to Ultrasonic and Bipolar Technologies.

INTRODUCTION: Vessel sealing technologies have improved surgical efficiency and outcomes. Ferromagnetic technology has potential utility in this area. The aim of this study was to evaluate ferromagnetic heating in sealing and dividing vessels. METHODS: A novel ferromagnetic (FM) sealer, FMsealer, was developed for sealing and dividing vessels. Using a swine in vivo model, the following endpoints were evaluated: (1) proof of concept, (2) 21-day survival surgery, and (3) comparison with ultrasonic (US) and/or bipolar (BP) devices for subjective outcomes. Seal burst strengths were measured in vitro. Mann-Whitney and Student's t test were used. RESULTS: After showing proof of concept, 5 swine underwent survival splenectomy, nephrectomy, hysterectomy, and mesenteric vessel division (arteries ranging from 1 to 7 mm in diameter) with necropsy after day 21 showing no evidence of surgical site bleeding. FM was equivalent to BP in tissue retention and superior to BP in spread/tissue desiccation, sticking, and charring (P ≤ .01). The FM was superior to US and BP in speed of 10 cm mesentery division (mean ± SD seconds): FM (12.9 ± 1.0 seconds), US (23.3 ± 4.4 seconds), BP (46.1 ± 5.2 seconds) (P ≤ .01 FM vs US or BP). Seal burst strength and success of sealing a 5-mm carotid artery were as follows (mean ± SD mmHg, % success burst strength >240 mm Hg): FM (710 ± 206 mm Hg, 94% success), US (848 ± 565 mm Hg, 79%), and BP (619 ± 373 mm Hg, 83%). CONCLUSION: Ferromagnetic heating is an effective and efficient technology for sealing and dividing of vessels. An initial prototype of the FMsealer compared favorably with commercially available products based on ultrasonic and bipolar technologies.

Amelioration of Anxiety Associated with Opioid Withdrawal by Activation of Spinal Mechanoreceptors Via Novel Heterodyned Whole Body Vibration.

Objectives: Opioid use disorder (OUD)-associated overdose deaths have reached epidemic proportions worldwide. An important driving force for relapse is anxiety associated with opioid withdrawal. We hypothesized that our new technology, termed heterodyned whole-body vibration (HWBV) would ameliorate anxiety associated with OUD. Methods: Using a randomized, placebo (sham)-controlled, double-blind study design in an NIH-sponsored Phase 1 trial, we evaluated 60 male and 26 female participants diagnosed with OUD and undergoing treatment at pain and rehabilitation clinics. We utilized the Hamilton Anxiety Scale (HAM-A) and a daily visual analog scale anxiety rating (1-10) to evaluate anxiety. Subjects were treated for 10 min 5X/week for 4 weeks with either sham vibration (no interferential beat or harmonics) or HWBV (beats and harmonics). The participants also completed a neuropsychological test battery at intake and discharge. Results: In OUD subjects with moderate anxiety, there was a significant improvement in daily anxiety scores in the HWBV group compared to the sham treatment group (p=3.41 × 10-7). HAM-A scores in OUD participants at intake showed moderate levels of anxiety in OUD participants (HWBV group: 15.9 ± 1.6; Sham group: 17.8 ± 1.6) and progressively improved in both groups at discharge, but improvement was greater in the HWBV group (p=1.37 × 10-3). Furthermore, three indices of neuropsychological testing (mental rotations, spatial planning, and response inhibition) were significantly improved by HWBV treatment. Conclusions: These findings support HWBV as a novel, non-invasive, non-pharmacological treatment for anxiety associated with OUD.

Intracranial electrical impedance tomography: a method of continuous monitoring in an animal model of head trauma.

BACKGROUND: Electrical impedance tomography (EIT) is a method that can render continuous graphical cross-sectional images of the brain's electrical properties. Because these properties can be altered by variations in water content, shifts in sodium concentration, bleeding, and mass deformation, EIT has promise as a sensitive instrument for head injury monitoring to improve early recognition of deterioration and to observe the benefits of therapeutic intervention. This study presents a swine model of head injury used to determine the detection capabilities of an inexpensive bedside EIT monitoring system with a novel intracranial pressure (ICP)/EIT electrode combination sensor on induced intraparenchymal mass effect, intraparenchymal hemorrhage, and cessation of brain blood flow. Conductivity difference images are shown in conjunction with ICP data, confirming the effects. METHODS: Eight domestic piglets (3-4 weeks of age, mean 10 kg), under general anesthesia, were subjected to 4 injuries: induced intraparenchymal mass effect using an inflated, and later, deflated 0.15-mL Fogarty catheter; hemorrhage by intraparenchymal injection of 1-mL arterial blood; and ischemia/infarction by euthanasia. EIT and ICP data were recorded 10 minutes before inducing the injury until 10 minutes after injury. Continuous EIT and ICP monitoring were facilitated by a ring of circumferentially disposed cranial Ag/AgCl electrodes and 1 intraparenchymal ICP/EIT sensor electrode combination. Data were recorded at 100 Hz. Two-dimensional tomographic conductivity difference (Δσ) images, rendered using data before and after an injury, were displayed in real time on an axial circular mesh. Regions of interest (ROI) within the images were automatically selected as the upper or lower 5% of conductivity data depending on the nature of the injury. Mean Δσ within the ROIs and background were statistically analyzed. ROI Δσ was compared with the background Δσ after an injury event using an unpaired, unequal variance t test. Conductivity change within an ROI after injury was likewise compared with the same ROI before the injury making use of unpaired t tests with unequal variance. RESULTS: Eight animal subjects were studied, each undergoing 4 injury events including euthanasia. Changes in conductivity due to injury showed expected pathophysiologic effects in an ROI identified within the middle of the left hemisphere; this localization is reasonable given the actual site of injury (left hemisphere) and spatial warping associated with estimating a 3-dimensional conductivity distribution in 2-dimensional space. Results are shown as mean ± 1 SD. When averaged across all 8 animals, balloon inflation caused the mean Δσ within the ROI to shift by -11.4 ± 10.9 mS/m; balloon deflation by +9.4 ± 8.8 mS/m; blood injection by +19.5 ± 11.5 mS/m; death by -12.6 ± 13.2 mS/m. All induced injuries were detectable to statistical significance (P < 0.0001). CONCLUSION: This study confirms that the bedside EIT system with ICP/EIT combination sensor can detect induced trauma. Such a technique may hold promise for further research in the monitoring and management of traumatically brain-injured individuals.

A study of family head shape: environment alters cranial shape.

A change in the type of cranial deformities (plagiocephaly) presenting to certain clinics has occurred. The purpose of this study was to compare infant head shapes against head shapes of their biologic parents to explore the roles of heredity and environment on cranial shape. Standardized family photographs and anthropometric measurements demonstrated that 30% of the infants had cranial widths 2 standard deviations above norm, while 4.6% had widths exceeding 3 standard deviations. Despite a mean age of only 8 months, 11.6% had widths that were already greater than that of 1 parent. These results demonstrate that plagiocephaly has taken on a new configuration, presenting not only with asymmetry, but also with excessive cranial width.

Implementation, calibration and accuracy testing of an image-enhanced endoscopy system.

This paper presents a new method for image-guided surgery called image-enhanced endoscopy. Registered real and virtual endoscopic images (perspective volume renderings generated from the same view as the endoscope camera using a preoperative image) are displayed simultaneously; when combined with the ability to vary tissue transparency in the virtual images, this provides surgeons with the ability to see beyond visible surfaces and, thus, provides additional exposure during surgery. A mount with four photoreflective spheres is rigidly attached to the endoscope and its position and orientation is tracked using an optical position sensor. Generation of virtual images that are accurately registered to the real endoscopic images requires calibration of the tracked endoscope. The calibration process determines intrinsic parameters (that represent the projection of three-dimensional points onto the two-dimensional endoscope camera imaging plane) and extrinsic parameters (that represent the transformation from the coordinate system of the tracker mount attached to the endoscope to the coordinate system of the endoscope camera), and determines radial lens distortion. The calibration routine is fast, automatic, accurate and reliable, and is insensitive to rotational orientation of the endoscope. The routine automatically detects, localizes, and identifies dots in a video image snapshot of the calibration target grid and determines the calibration parameters from the sets of known physical coordinates and localized image coordinates of the target grid dots. Using nonlinear lens-distortion correction, which can be performed at real-time rates (30 frames per second), the mean projection error is less than 0.5 mm at distances up to 25 mm from the endoscope tip, and less than 1.0 mm up to 45 mm. Experimental measurements and point-based registration error theory show that the tracking error is about 0.5-0.7 mm at the tip of the endoscope and less than 0.9 mm for all points in the field of view of the endoscope camera at a distance of up to 65 mm from the tip. It is probable that much of the projection error is due to endoscope tracking error rather than calibration error. Two examples of clinical applications are presented to illustrate the usefulness of image-enhanced endoscopy. This method is a useful addition to conventional image-guidance systems, which generally show only the position of the tip (and sometimes the orientation) of a surgical instrument or probe on reformatted image slices.

Endoscopic aqueductoplasty and interventriculostomy for the treatment of isolated fourth ventricle in children.

OBJECTIVE: There are different approaches for the treatment of isolated fourth ventricle in children, including a suboccipital ventriculoperitoneal shunt, suboccipital craniotomy with microsurgical fenestration, and endoscopic fenestration. We discuss the indications, surgical methods, and outcome of 18 patients who underwent endoscopic treatment for isolated fourth ventricle. METHODS: We retrospectively reviewed the medical histories of 18 patients with an isolated fourth ventricle. Surgical procedures included endoscopic aqueductoplasty, endoscopic aqueductoplasty with a stent, endoscopic interventriculostomy (lateral ventricle or third ventricle to fourth ventricle), and endoscopic interventriculostomy with a stent. Operations were performed between July 1997 and June 2002. The mean age of the patients at the time of surgery was 3 years. The mean follow-up was 29 months. All patients had a supratentorial ventriculoperitoneal shunt. RESULTS: Clinical symptoms (impairment of consciousness, tetraparesis, and ataxia) improved in all patients. Reduction of the size of the fourth ventricle was observed in all patients. Seven patients required reoperation because of restenosis (39% revision rate). Restenosis occurred between 2 weeks and 7 months after surgery (average, 3 mo). Four patients underwent reoperation with stent placement, and three patients underwent reaqueductoplasty. We had the following complications: one infection, one asymptomatic subdural hygroma, one transient oculomotor paresis, and one permanent oculomotor paresis (4 [22%] of 18 patients). CONCLUSION: The significant failure rate of fourth ventricle shunts has led to the development of alternative treatment methods. Endoscopic aqueductoplasty or interventriculostomy presents an effective, minimally invasive, and safe procedure for the treatment of isolated fourth ventricle in pediatric patients. Compared with suboccipital craniotomy and microsurgical fenestration, endoscopic aqueductoplasty is less invasive, and compared with fourth ventricle shunts, it is more reliable and effective.