Instantaneous 3D EEG Signal Analysis Based on Empirical Mode Decomposition and the Hilbert–Huang Transform Applied to Depth of Anaesthesia

Depth of anaesthesia (DoA) is an important measure for assessing the degree to which the central nervous system of a patient is depressed by a general anaesthetic agent, depending on the potency and concentration with which anaesthesia is administered during surgery. We can monitor the DoA by observing the patient’s electroencephalography (EEG) signals during the surgical procedure. Typically high frequency EEG signals indicates the patient is conscious, while low frequency signals mean the patient is in a general anaesthetic state. If the anaesthetist is able to observe the instantaneous frequency changes of the patient’s EEG signals during surgery this can help to better regulate and monitor DoA, reducing surgical and post-operative risks. This paper describes an approach towards the development of a 3D real-time visualization application which can show the instantaneous frequency and instantaneous amplitude of EEG simultaneously by using empirical mode decomposition (EMD) and the Hilbert–Huang transform (HHT). HHT uses the EMD method to decompose a signal into so-called intrinsic mode functions (IMFs). The Hilbert spectral analysis method is then used to obtain instantaneous frequency data. The HHT provides a new method of analyzing non-stationary and nonlinear time series data. We investigate this approach by analyzing EEG data collected from patients undergoing surgical procedures. The results show that the EEG differences between three distinct surgical stages computed by using sample entropy (SampEn) are consistent with the expected differences between these stages based on the bispectral index (BIS), which has been shown to be quantifiable measure of the effect of anaesthetics on the central nervous system. Also, the proposed filtering approach is more effective compared to the standard filtering method in filtering out signal noise resulting in more consistent results than those provided by the BIS. The proposed approach is therefore able to distinguish between key operational stages related to DoA, which is consistent with the clinical observations. SampEn can also be viewed as a useful index for evaluating and monitoring the DoA of a patient when used in combination with this approach

Effect of Apex Locator and Electronic Pulp Tester on Pacemaker Function: An In Vitro study

This study evaluated the potential for interference of electronic pulp tester, electronic apex locators and diathermy with pacemaker function. Dental Instruments used. Apex locators: 1. Root ZX (J Morita Corp., Japan), 2. Propex (Dentsply Maillefer, Ballaigues, Switzerland), 3. Mini Apex locator (SybronEndo, Anaheim, CA, USA). Pulp tester: 1. Parkell pulp vitality tester (Farmingdale, NY, USA). Diathermy: 1. Neomed 250 B Pacing system used: 1. Medtronic (KVDD901. The study design consisted of directly connecting the pacemaker lead, EAL, and oscilloscope across a 150-ohm resistor. With the electronic apex locator/ electronic pulp tester/diathermy operating on a flat bench top, the telemetry wand was held directly over the pacemaker to monitor the pacing pattern for a period of 30 s. A negative control was conducted with the pacemaker alone. Pacemaker activity was continuously recorded on the EGM printout of the telemetric programmer. These recordings were then examined for pacer inhibition, noise reversion or inappropriate pacemaker pulses. CONCLUSION: From the results of the present study, it may be concluded, 1. The tested Electronic Apex Locators Root ZX (J Morita Corp., Japan), Propex (Dentsply Maillefer, Ballaigues, Switzerland), Sybron Endo mini (SybronEndo, Anaheim, CA, USA) do not interfere with cardiac pacemaker function. 2. The tested Electric pulp tester, Parkell pulp vitality tester (Farmingdale, NY, USA) does not interfere with cardiac pacemaker function. 3. The results show that the use of Diathermy (Neomed 250 B) interfered with the normal pacing, leading to complete inhibition of the pacing system. Manufacturers of EALs continue to warn against the use of their devices in patients with cardiac pacemakers despite the absence of evidence to support such claims. Although they may possess bench test data similar to those shown above, the lack of clinical data would make it difficult to obtain FDA approval for the devices without such warnings. Human trials are needed to clarify this issue

Evaluation and application of a RBF neural network for online single-sweep extraction of SEPS during scoliosis surgery

IEEE Transactions on Biomedical Engineering, 54(7): pp. 1300-1308.A method for on-line single sweep detection of somatosensory evoked potentials (SEPs) during intraoperative neuromonitoring is proposed. It is based on a radial-basis function neural network with Gaussian activations. In order to improve its tracking capabilities, the radial-basis functions location is partially learnt sweep-by-sweep; the training algorithm is effective, though consistent with real-time applications. This new detection method has been tested on simulated data so as to set the network parameters. Moreover, it has been applied to real recordings obtained from a new neuromonitoring technique which is based on the simultaneous observation of the SEP and of the evoked H-reflex elicited by the same electric stimulus. The SEPs have been extracted using the neural network and the results have then been compared to those obtained by ARX filtering and correlated with the spinal cord integrity information obtained by the H-reflex. The proposed algorithm has been proved to be particularly effective and suitable for single-sweep detection. It is able to track both sudden and smooth signal changes of both amplitude and latency and the needed computational time is moderate

Treatment of hypertrophic scars and keloids using an intralesional 1470 nm bare-fibre diode laser: a novel efficient minimally-invasive technique

Hypertrophic and keloid scars result from abnormal wound healing and can have a variable response to a number of available treatment modalities. The evolution of laser treatments in recent years has shown a wide range of clinical applications including their use in the treatment of scars. We investigated the effectiveness of a 1470 nm diode laser using an intralesional optical fibre delivery device in the treatment of hypertrophic and keloid scars. We evaluated its safety and efficacy as a novel and minimally invasive treatment alternative for scar modulation and volume reduction. A prospective cohort study was performed involving 21 patients with hypertrophic scars (HS) (n = 9) and keloids (n = 12) resulting from various aetiology. Patients were treated with one to three treatment sessions. Comprehensive evaluations were performed using the Vancouver Scar Scale, Doppler ultrasound, Cutometer, Mexameter and PeriCam PSI. Scar thickness was reduced by an average of 0.308 ± 0.138 cm (p < 0.001). In particular the two subgroups showed a significant 27.7% and 28.2% reduction in scar thickness of HS and Keloids, respectively. Scar firmness showed a significant improvement of 1.2% (p < 0.05) for HS, though for keloids this was 0.4% (p = 0.26). Keloids had a significant reduction in pigmentation at 21.3%. Blood perfusion had a significant reduction of 29.6% in HS and 22.7% in Keloids. Overall VSS total score improvement of 42% in the HS and at 37.9% in the Keloid subgroup. No adverse events such as hypo/hyperpigmentation, skin infection, or recurrence were reported. This study shows that the intralesional 1470 nm bare-fibre diode laser significantly improved hypertrophic and keloid scars based on both subjective and objective analyses and supports this type of laser therapy as a safe and effective minimally-invasive treatment option

Endoscopic tissue liquidisation of the prostate, bladder and kidney

Endoscopic techniques have revolutionised the practice of all specialities of surgery. Endoscopic access has been either via a natural route, such as the urethra, or percutaneously, as in percutaneous intrarenal stone surgery. Potential endoscopic procedures for bulk tissue removal have been limited by the need to reduce that tissue to a size smaller than the endoscopic channel used. An attempt has been made to create a device that will liquidise and aspirate tissue through an endoscope, This Instrument has been called the Endoscopic Liquidiser and Surgical Aspirator (ELSA). This report details the design and development of the ELSA which has led to its clinical application. The device is 5 mm in diameter and is used through a specially made endoscope of 8.5 mm outer diameter (approximately 27 French). It consists of a high speed rotating blade mounted in a housing that provides irrigation for efficient 1iquidisation and a channel for aspiration of the tissue. Laboratory evaluation was measured by the removal rates of different tissues. The optimum parameters of blade speed, irrigation flow and aspiration were established after a series of controlled experiments. Blade shape was also found to be important and a study of the material strengths of different tissues was required to establish that blade design should vary for each tissue used. Under optimum laboratory conditions fresh human prostate could be removed at 2.4 g/min and renal cortex at 14.6 g/min. The resultant aspirate contained particles ranging from 10 microns to 3 mm, but the majority were less than 200 microns. Flow cytometry was required as the only reasonable method of rapid pathological diagnosis. The action of the ELSA did not confer any Inherent haemostatic benefit and a diathermy plate was added to the tip of the instrument. The ELSA was successfully used to remove benign prostatic tissue from 7 patients with bladder outflow obstruction. However the procedures were slow and visualisation was poor once the liquidisation began. The mean operating time was 85 minutes (range 50 - 120). 1 patient suffered a fatal capsular perforation, but otherwise morbidity v/as not dissimilar from a control group undergoing a standard transurethral diathermy resection. 6'7 patients regained an improved stream with good control. The ELSA was used in the same transurethral method for the removal of superficial bladder tumours in 10 patients. The same problem of impaired vision was found, but the removal was very rapid as one would expect with a soft non-fibro\is material. The postoperative morbidity was greater than in a control group using a diathermy resectoscope due to bladder perforation with the ELSA in 1 case. A percutaneous endoscopic nephrectomy has been achieved in 2 dogs. Each kidney was embolised with "Ethibloc" (a material that completely occupies all arterial capillary beds), An Intrarenal approach was compared with an extrarenal, retroperitoneal one; the latter using carbon dioxide insufflation. Both procedures were successful. Haeraostasis was not a problem. These may be suitable clinical techniques for the minimally invasive removal of infected kidneys prior to transplantation. The presence of stones would not be a problem because of the ability of the ELSA to fragment and aspirate stone particles as efficently as any ultrasound device. This was confirmed in a series of laboratory tests on various stone types and in 5 patients with urinary stones. An extension of the concept of minimally invasive bulk tissue aspiration is the integration of robotics into this form of surgery. The ELSA has been attached to an industrial robot. The mechanism of a transurethral prostatectomy has been studied in order to program the robot. A robotic prostatectomy in a simulation model has been performed. Each procedure can be preprogrammed according to the dimensions of the gland. The in vitro study confirmed that the robot was consistent and therefore safe; and rapid (mean removal time 5 rains) because visualisation was not required for orientation. In conclusion, the ELSA has proved to be ati efficient instrument for endoscopic tissue removal but its clinical superiority is only for less fibrous tissues and improved visualisation will be required. It still requires ancillary methods for haemostasis and the use of a capillary embolisation technique in the kidney may have applications elsewhere. The robotic study was not just an academic exercise. Robotics will be a feature of future surgery

Investigation of a holistic human-computer interaction (HCI) framework to support the design of extended reality (XR) based training simulators

In recent years, the use of Extended Reality (XR) based simulators for training has increased rapidly. In this context, there is a need to explore novel HCI-based approaches to design more effective 3D training environments. A major impediment in this research area is the lack of an HCI-based framework that is holistic and serves as a foundation to integrate the design and assessment of HCI-based attributes such as affordance, cognitive load, and user-friendliness. This research addresses this need by investigating the creation of a holistic framework along with a process for designing, building, and assessing training simulators using such a framework as a foundation. The core elements of the proposed framework include the adoption of participatory design principles, the creation of information-intensive process models of target processes (relevant to the training activities), and design attributes related to affordance and cognitive load. A new attribute related to affordance of 3D scenes is proposed (termed dynamic affordance) and its role in impacting user comprehension in data-rich 3D training environments is studied. The framework is presented for the domain of orthopedic surgery. Rigorous user-involved assessment of the framework and simulation approach has highlighted the positive impact of the HCI-based framework and attributes on the acquisition of skills and knowledge by healthcare users

Cerebral blood flow in the pig : a study of Xenon-133 clearance techniques

Cerebrovascular disease is an important cause of death. The number of cerebrovascular complaints is increasing, mainly as a consequence of increasing the mean lifetime. Functioning of the brain is dependent on blood supply. A temporary or prolonged reduction of total or regional cerebral blood flow (c.b.f.) may lead to irreversible damage of cerebral tissue and loss of neurological functions. Therefore the measurement of cerebral blood flow, preferably in different regions, is clinically important. Several methods of measuring c.b.f. have been developed. The applicability of a method in a clinical situation depends on its traumatic aspects. A brief survey of the methods of c.b.f. measurement is given at the end of this chapter. The clinical method used most frequently is the Xe-133 clearance technique. The Xe-133 is administered by three different routes, intra-arterial, intravenous or by inhalation. This thesis mainly deals with the intraarterial injection technique, evaluated on the pig as experimental animal

Evaluación histológica de los márgenes quirúrgicos en cirugía con láser de tejidos blandos de la cavidad oral

Objetivo: Determinar los márgenes quirúrgicos para evaluar histológicamente (ex vivo) los efectos térmicos tisulares provocados por diferentes tipos de instrumentos quirúrgicos y determinar la viabilidad de los especímenes (in vivo) sometidos a tratamiento con láser en mucosa oral humana para diagnóstico anatomopatológico. Diseño del estudio: Se efectuaron cortes en mucosa de lenguas de cerdo con diferentes láseres (Er:YAG a 2W con y sin espray aire/agua y 4W con y sin espray aire/agua; CO2, 3,5W y 7W en modo pulsado y a 7W en modo continuo; Diodo a 3,5W y 3,5W boost en modo pulsado; Nd:YAG a 6W, 40Hz) y con electrobisturí (5W) y bisturí convencional como control. Se evaluaron alteraciones morfológicas macroscópica y microscópicamente. Posteriormente, se realizó una evaluación de viabilidad de especímenes in vivo (lesiones benignas de mucosa oral humana) sometidos a un análisis antomopatológico tras la irradiación con láser. Resultados: Los resultados de este estudio revelaron que los Instrumentos quirúrgicos que provocaron mayor Extensión de daño Tisular fueron los Láseres Nd:YAG (670,68μm), seguidos del Diodo a 3,5W boost PW (626,82μm), el de CO2 a 7W CW (571,18μm), el de CO2 a 7W PW (485,45μm), el Diodo a 3,5W PW (456,15μm), el electrobisturí (409,57μm) y, por último, del láser de CO2 a 3,5W PW (306,19μm) y el Er:YAG (74,66μm), independientemente de la potencia, modo o espray aire/agua utilizados. También revelaron una asociación entre la Extensión del Daño Tisular y el Grado de Carbonización (r= 0,789; p=0,01) y una asociación entre la Extensión del Daño Tisular y la Regularidad de la incisión (r= -,299; p=0,01). El diagnóstico histológico siempre fue posible para todas las muestras de mucosa oral humana extirpadas con el láser de CO2 a 3,5W en modo de emisión pulsado. Conclusiones: Los resultados del estudio sugieren que los láseres pueden ser utilizados en biopsias de tejidos blandos de la cavidad oral, permitiendo un análisis antomopatológico correcto, si se tienen presentes los efectos biológicos derivados de cada tipo de láser. El láser Er:YAG mostró su potencial para biopsias de la mucosa oral, asegurando una evaluación histológica exitosa, y el Láser de CO2 a 3,5W en modo pulsado se reveló como la mejor opción para cirugías con hemostasis