Biomedical Engineering: Applications, Basis and Communications

An indirect calorimetry system of measuring oxygen consumption and carbon dioxide production has been frequently used for preterm infants. The energy consumption and metabolic measurements are based on flow-through technology. The noninvasive measurement feature of the indirect calorimeter is widely used in pediatric clinical research. However, the indirect calorimeter has several limitations for small preterm infants, particularly the ill infant weighing < 1.0 kg. In this paper, we propose some technologies and methodologies to improve the performance of the indirect calorimetry. According to these technologies and methodologies, we redesign the indirect calorimeter proposed in our pervious study. The laboratory evaluation at the different alcohol combustion rates and several exhaust flow rates is used to survey the improved performance. As the results, the accuracy and precision is enhanced by these methods and the lowest oxygen consumption rate, 4.35 ml/min, fits for baby weight of 0.66 kg. It is demonstrated that the performances of new indirect calorimetry are substantially improved. It can be applied to calculate the energy consumption and metabolic rate for low-birth-weight infants in clinical research.

A neural network system is presented for controlling a two-link dynamic arm model where the task is to move the arm from any initial position to any final position in the sagittal plane. The controller produces joint torque-lime profiles that begin and end with equilibrium values at the initial and final positions, respectively. A memory type neural network is trained by supervised learning methods to predict the joint's static equilibrium torque values corresponding to joint angles. A reinforcement learning network is used to determine the parameters needed for synthesis of the torque-time profiles for each joint. The reinforcement signal is computed based on the distance between the desired end point position and velocity and the states achieved based on the generated torque profiles. The general pattern of the torque-time plots is decided a priori according to the literature. The methods of training and an illustrative example of the algorithm's performance are presented.

Following the promotion of living quality and the implementation of the national health instrumentation program in Taiwan, the demand of research and development for localized medical modalities has become critical. With corporation with Chang Gung Memorial Hospital, the Medical Automation and Rehabilitation Engineering Research Center (MAREC) in Chang Gung University has been dedicated itself to the development of pivotal technologies for medical mechatronics systems / modalities and perform clinical evaluation of newly developed modalities. In this paper, part of the localized medical mechatronics systems and rehabilitative modalities developed in Chang Gung University (Taiwan) was reported.

This paper concerned with results of implantation of the Phoenix-7 total artificial heart (TAH) in the growing calves. Experimental study had been conducted 41 times in 41 calves. All the calves could breathe, stand, eat and void by themselves in two hours after operation. The causes of death essentially included respiratory failure, sepsis, hemorrhage shock, thrombo-embolism, and multiple organ failure. Autopsy was performed in all deaths. The phoenix hearts were opened and examined. Blood morphology and blood chemistry were welt analyzed. Deformation of the red blood cells was found in most of the cases. Cell destruction, however, was not obvious. Besides, there was no evidence of red blood cell aggregation.

Initial clinical experience was undertaken for a 46-year-old male who was in cardiogenic shock. The patient was indwelled with intra-aortic balloon counter-pulsation (IABP) and supported by extra-corporeal membrane oxygenator (ECMO) before the implantation. With IABP and ECMO, the patient's blood pressure was maintained at 90/60mmHg, but oliguria persisted with the complication of hemolysis. The patient was then implanted with the Phoenix-7 TAH and the condition was improved tremendously. With the TAH, the patient's blood pressure was maintained at 90∼100mHg / 40∼50mmHg. Cardiac output was adequately maintained at 4.2~5.8 Llmin by an operating model on modifying the parameters of driving air pressure for both the right and left hearts, heart rate and systolic ratio. The patient had been on the device for 15 days until a successful simultaneous orthotopic heart and heterotopic kidney transplantation from a suitable donor was undertaken.

The development of new image techniques enables the early detection of bone tumors in the extremities in the past two decades. In addition, new advance of adjuvant therapy improves the long-term survival of patients with primary bone malignancies. Since the primary bone malignancy frequently occurs at the metaphysis of long bones of pediatric patients in the first and second decade, many patients have to face the late problems of limb length discrepancy after the limb salvage operation. Since the inevitable limb length discrepancy will interfere the functional outcomes and cosmetic appearance, the reconstruction of limb defect after limb salvage remains a challenge. Several options of reconstruction are available for these patients, including resection arthrodesis, rotationplasty, osteochondral allograft reconstruction, and endoprosthetic reconstruction. All these methods are difficult to address the limb length discrepancy. The development of expandable endoprosthetic reconstruction makes limb-salvage surgery feasible in the skeletally immature and provides another choice of solution. This article presents the current status of custom-expandable endoprosthetic reconstruction in the skeletally immature patients after wide resection of primary bone malignancies in the extremity. The surgical options, complications and functional results will be emphasized.

Basically these expandable endoprostheses can be classified according to the expansion design. Recent reports demonstrated that the results of expandable prosthesis in the growing children are rather acceptable. Some patients can regain the equal limb length after expansion of the prosthesis. However these patients have to take several expansion procedures for the equality of limb length during the growing period. A rather high complication rate of either endoprosthesis-related or disease-associated still needs to be settled in the near future. These include mechanical failure of the expansion mechanism, extensive metallosis, aseptic loosening, fatigue fracture, flexion contracture, local recurrence, delayed wound healing, fat embolism, local overgrowth of counterpart bone, nerve palsy, infection, and bone fracture. Some patients even require an amputation even after expandable endoprosthesis reconstruction because of difficult reconstruction or severe functional impairment. However, with regard to difficult rehabilitation for patients under 8 years, amputation or alternative options need to be considered. A comprehensive discussion with the parents and patient about the detailed treatment protocol is needed before performing reconstruction using expandable endoprosthesis.

A duplicated mold of the residual limb of an amputee is usually needed to make the socket of prosthesis for the patient. However, traditional means to duplicate a positive mold is time-consuming, patient suffering and intensive manual-efforts required. The study has developed a prototype system that allows a prosthetist to construct the computer-aided design(CAD) model of residual limb easily using it's digitized points based on the concept of reverse engineering. First of all, the topographic data of a residual limb is captured using a non-intrusive scanning machine. The scanned data is then used as the input of a self-developed system that is based on the theories of B-spline curve and lofted surface to process the digitized points. The CAD model can then be built and transferred to a computer-aided manufacturing(CAM) system to generate the code for a computer numerical control(CNC) machine to make the duplicated mold of the residual limb.