Medical engineering & physics
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Bone loss due to thermonecrosis may weaken the purchase of surgically placed screws and pins, causing them to loosen post-operatively. The goal of this study was to determine how differences in applied drilling forces affect the temperature of cortical tissue near the drilling site. ⋯ Furthermore, increasing the drilling force resulted in a significant decrease (P=0.001) in the average duration of temperature elevations above 50 degrees C. The results of the current study demonstrate that by the application of a larger force to the drill, both maximum cortical temperatures and their duration above 50 degrees C may be effectively reduced, decreasing the potential for thermal necrosis in the neighboring cortical bone.
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Prolonged sitting is generally accepted as a high risk factor in low back pain and it is frequently suggested that a lordotic posture of the lumbar spine should be maintained during sitting. We asked whether the sagittal curvature of the lumbar spine during sitting is affected by the seat tilt, backrest and the direction of the synchronised mechanism of the back and seat tilt (synchro tilt). Two office chairs were tested by multibody analysis interfacing a human model with a chair model. ⋯ These lumbar spine segmental angles are not sensitive to the backrest height. In contrast, a synchro tilt concept with a reduction of the seat's posterior tilt while the backrest is reclined causes a strong reduction of the lumbar lordosis in backrest recline with a maximum reduction from 11.7 to 2.8 degrees in L4/5. As a consequence of these results, a synchro tilt concept with a posterior tilt of the seat while the backrest is reclined is preferable from the lumbar spine kinematics point of view.
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Clinical Trial
A bioacoustic method for timing of the different phases of the breathing cycle and monitoring of breathing frequency.
It is well known that the flow of air through the trachea during respiration causes vibrations in the tissue near the trachea, which propagate to the surface of the body and can be picked up by a microphone placed on the throat over the trachea. Since the vibrations are a direct result of the airflow, accurate timing of inspiration and expiration is possible. ⋯ One problem associated with the bioacoustic method is its sensitivity for acoustic disturbances, because the microphone tends to pick up all vibrations, independent of their origin. A signal processing method was developed that makes the bioacoustic method clinically useful in a broad variety of situations, for example in intensive care and during certain heart examinations, where information about both the precise timing and the phases of breathing is crucial.
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In laboratory animals as well as in human beings a depth of anaesthesia, where the subject has no pain or recall of events from the surgery, should be provided. Haemodynamic parameters such as heart rate and blood pressure are not a guarantee for an optimal depth of anaesthesia, especially when using neuromuscular blocking agents (NMBA). A number of studies suggest that the Middle Latency Auditory Evoked Potentials (MLAEP) contain information about the state of consciousness in humans. ⋯ The decrease in the DAI correlated well with the loss of stimulus response. In conclusion, MLAEP could be used as an indicator of depth of anaesthesia in rats during Hypnorm vet. and Dormicum administration. However studies applying other anaesthetic drugs should be carried out, before a conclusion of the general utility of the method can be made.
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Failures of Gamma nails which treat unstable femoral fractures have been reported. In this paper, a finite element model to include a Gamma nail within a fractured femur was used to investigate the stresses in the Gamma nail. The effects for different types of fracture were investigated. The results show that its use for subtrochanteric fractures will cause higher stresses at the lag screw and upper distal screw insertion holes in the nail than when used for femur neck fractures.