Medical & biological engineering & computing
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Med Biol Eng Comput · Jun 2013
Development and validation of a pressure-type automated quantitative sensory testing system for point-of-care pain assessment.
Quantitative sensory testing (QST) can provide useful information about the underlying mechanisms involved in chronic pain. However, currently available devices typically employed suffer from operator-dependent effects, or are too cumbersome for routine clinical care. This paper presents the design and initial validation of a novel automated pressure-pain type QST platform, termed the multi-modal automated sensory testing (MAST) system. ⋯ Validation of the controller using three ramp rates (64, 248, and 496 kPa/s) and six pressures (32, 62, 124, 273, 620, and 1116 kPa) showed an overall mean error of 1.7 % for applied stimuli. Clinical evaluation revealed decreased pressure pain thresholds in chronic pain patients (98.07 ± SE 16.34 kPa) compared to pain free, healthy control subjects (259.88 ± SE 33.54 kPa, p = 0.001). The MAST system is portable and produces accurate, repeatable stimulation profiles indicating potential for point-of-care applications.
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Med Biol Eng Comput · Feb 2013
Clinical TrialDeformation and pressure propagation in deep tissue during mechanical painful pressure stimulation.
Manual palpation or pressure stimulation is often used for pain sensitivity assessment. The aim of the current study was to define a method for investigating the relation between pressure pain sensitivity and pressure propagation in soft or harder muscles. Three-dimensional finite-element computer-models were developed to simulate the tissue stress and strain distribution during pressure stimulation on the tibialis anterior and gastrocnemius muscles. ⋯ Average pressure pain thresholds were significantly lower for the tibialis anterior compared with the gastrocnemius muscle (319 vs. 432 kPa) These data show different pressure propagation profiles in soft and hard muscle at the same pressure pain sensation level. This new approach is relevant as the clinical routine assesses all muscles equally. This results in a different exposure to pressure in relation to the muscle evaluated which may affect the outcome of the examination.
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A method for deriving respiration from the pulse photoplethysmographic (PPG) signal is presented. This method is based on the pulse width variability (PWV), and it exploits the respiratory information present in the pulse wave velocity and dispersion. It allows to estimate respiration signal from only a pulse oximeter which is a cheap and comfortable sensor. ⋯ For comparison purposes, we have also obtained a respiratory rate estimation from other known methods which involve ECG, BP, or also PPG signals. In addition, we have also combined respiratory information derived from different methods which involve only PPG signal, obtaining a respiratory rate error of -0.17 ± 6.67% (-2.16 ± 12.69 mHz). The presented methods, PWV and combination of PPG derived respiration methods, avoid the need of ECG to derive respiration without degradation of the obtained estimates, so it is possible to have reliable respiration rate estimates from just the PPG signal.
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Med Biol Eng Comput · Dec 2012
Optimal chest compression in cardiopulmonary resuscitation depends upon thoracic and back support stiffness.
A biomechanical analysis of the constant peak displacement and constant peak force methods of cardiopulmonary resuscitation (CPR) has revealed that optimal CC performance strongly depends on back support stiffness, CC rate, and the thoracic stiffness of the patient being resuscitated. Clinically the results presented in this study suggest that the stiffness of the back support surfaces found in many hospitals may be sub-optimal and that a backboard or a concrete floor can be used to enhance CC effectiveness. ⋯ In addition, it is important for clinicians to note that very high peak sternal forces, exceeding the limit above which severe chest wall trauma and abdominal injury occurs, may be required for optimal CC during peak force CPR on patients with very stiff chests. In these cases an alternative CPR technique may be more appropriate.
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Med Biol Eng Comput · Jul 2012
Accuracy and efficacy of thoracic pedicle screws in scoliosis with patient-specific drill template.
With the rapid increase in the use of thoracic pedicle screws in scoliosis, accurate and safe placement of screw within the pedicle is a crucial step during the scoliosis surgery. To make thoracic pedicle screw placement safer various techniques are used, Patient-specific drill template with pre-planned trajectory has been thought as a promising solution, it is critical to assess the efficacy, safety profile with this technique. In this paper, we develop and validate the accuracy and safety of thoracic transpedicular screw placement with patient-specific drill template technique in scoliosis. ⋯ This method significantly reduces the operation time and radiation exposure for the members of the surgical team, making it a practical, simple and safe method. The potential use of such a navigational template to insert thoracic pedicle screws in scoliosis is promising. The use of surgical navigation system successfully reduced the perforation rate and insertion angle errors, demonstrating the clear advantage in safe and accurate pedicle screw placement of scoliosis surgery.