Biomedical instrumentation & technology / Association for the Advancement of Medical Instrumentation
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Pneumatic tourniquets are routinely used in limb surgery to provide a bloodless operating field, but they are known to cause nerve injuries. Simulation results based on the hypothesis that axial compression of nerves is responsible for a certain class of these mechanically induced injuries are in substantial accord with clinical observations. ⋯ The smallest axial strains are induced by a tourniquet design for which the applied pressure distribution rolls off as gradually as possible; according to the axial-strain hypothesis, such a design will markedly decrease a tourniquet's inherent potential for injury. Use of a wider cuff in and of itself will not reduce axial strain, so if the hypothesis is correct, a wider cuff would not be intrinsically safer than a regular cuff, a result that is contrary to current opinion.
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Biomed Instrum Technol · May 1993
A new sodium-nitroprusside-infusion controller for the regulation of arterial blood pressure.
Automatic optimization of the infusion rate of sodium nitroprusside (SNP) is achieved by an integrated hardware-software closed-loop controller implemented as a small bedside device. A microprocessor-based blood pressure monitor controls an infusion pump. The shape of the arterial pressure wave is digitally sampled; its analysis incorporates artifact-detection and -rejection routines. ⋯ The first 240 minutes of the postoperative period were closely watched, taking into account 1) the percentage of time during which MAP was within the 10-mmHg wide frame above the target pressure (target gap); 2) the mean difference of pressure values that crossed the boundary of the target gap; 3) the mean SNP-infusion rate. With automatic control, the time mean arterial pressure values were located in the target gap during the first hour amounted to 72.8 +/- 6.7%, vs 51.2 +/- 10.3% in the manual-control group. In the second hour, it was 79.3 +/- 2.5% vs 67.4 +/- 11.7% (p < 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)
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Due to the eight stresses of flight and Federal Aeronautics Administration (FAA) requirements, biomedical equipment that is utilized in aeromedical transports presents certain challenges that the biomedical department should be aware of. U. S. ⋯ Temporary pacers and automatic defibrillators should also be set to a mode where the vibrations of flight will not trigger any errant behavior. With the proper precautions, aeromedical transports will continue to be a rapidly growing transport system for both trauma patients and intrahospital transfers. With a little research, the biomedical engineer can also be a valuable asset to the ground support crew.
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Biomed Instrum Technol · May 1992
The feasibility of spectrophotometric measurements of arterial oxygen saturation from the fetal scalp utilizing noninvasive skin-reflectance pulse oximetry.
In in-vivo animal experiments, the authors evaluated the feasibility of measuring arterial oxyhemoglobin saturation (SaO2) noninvasively during simulated delivery conditions with a skin-reflectance pulse oximeter sensor attached to the fetal scalp. The optical reflectance sensor consisted of three pairs of red and infrared light-emitting diodes and a concentric array of six identical photodiodes. ⋯ Each sensor was interfaced to a commercial Datascope ACCUSTAT transmittance pulse oximeter, adapted to perform as a reflectance pulse oximeter. This method, once successfully developed, could potentially be used in combination with other fetal monitoring techniques to elucidate the role of noninvasive pulse oximetry in reducing fetal morbidity and mortality.