Microprocessor-control of drug infusion for automatic blood-pressure control

Evolution of blood pressure control identification in lieu of post-surgery diabetic patients: a review

The blood pressure disparity is the major problem in post-operative surgery especially diabetic patients, because there is substantial interrelation between diabetic and hypertension and this abnormality creates complicated problems and needs to be controlled by continuous monitoring based on the severity. To overcome this problem, implementation of automatic drug infusion is required for critical patients, by which workload of the clinical staffs are reduced. Most commonly the sodium nitroprusside (SNP) is used to reduce the blood pressure in fast action based on the prescribed level. In this paper three different types of estimation techniques (PID, IMC and MPC) are uses to identify the valuation. The strength of the projected controller performance is evaluated under different types of patients such as sensitive, and normal along with insensitive patients. Therefore, this paper review the validation results based on the optimized SNP infusion rate for persistent Blood pressure control compare then the reviewed methods. The MATLAB simulation is used to evaluate the efficiency of the proposed work and obtain the results based on the projected values.

A model for technology assessment as applied to closed loop infusion systems. Technology Assessment Task Force of the Society of Critical Care Medicine

OBJECTIVES

To test a model for the assessment of critical care technology on closed loop infusion control, a technology that is in its early stages of development and testing on human subjects.

DATA SOURCES

A computer-assisted search of the English language literature and reviews of the gathered data by experts in the field of closed loop infusion control systems.

STUDY SELECTION

Studies relating to closed loop infusion control that addressed one or more of the questions contained in our technology assessment template were analyzed. Study design was not a factor in article selection. However, the lack of well-designed clinical outcome studies was an important factor in determining our conclusions.

DATA EXTRACTION

A focus person summarized the data from the selected studies that related to each of the assessment questions. The preliminary data summary developed by the focus person was further analyzed and refined by the task force. Experts in closed loop systems were then added to the group to review the summary provided by the task force. These experts' comments were considered by the task force and this final consensus report was developed.

DATA SYNTHESIS

Closed loop system control is a technological concept that may be applicable to several aspects of critical care practice. This is a technology in the early stages of evolution and much more research and data are needed before its introduction into usual clinical practice. Furthermore, each specific application and each device for each application (e.g., nitroprusside infusion, ventilator adjustment), although based on the same technological concept, are sufficiently different in terms of hardware and computer algorithms to require independent validation studies.

CONCLUSIONS

Closed loop infusion systems may have a role in critical care practice. However, for most applications, further development is required to move this technology from the innovation phase to the point where it can be evaluated so that its role in critical car practice can be defined. Each application of closed loop infusion systems must be independently validated by appropriately designed research studies. Users should be provided with the clinical parameters driving each closed loop system so that they can ensure that it agrees with their opinion of acceptable medical practice. Clinical researchers and leaders in industry should collaborate to perform the scientifically valid, outcome-based research that is necessary to evaluate the effect of this new technology. The original model we developed for technology assessment required the addition of several more questions to produce a complete analysis of an emerging technology. An emerging technology should be systematically assessed (using a model such as the model developed by the Society of Critical Care Medicine), before its introduction into clinical practice in order to provide a focus for human outcome validation trials and to minimize the possibility of widespread use of an unproven technology.

Control strategies for arterial blood pressure regulation

This paper reviews the theoretical development of automatic control strategies for arterial blood pressure regulation. The literature is classified by control strategy. Proportional-integral-derivative controllers, optimal controllers, adaptive controllers, and rule-based controllers are the most commonly encountered strategies in the literature. A brief description of each control scheme is given, followed by examples of each from the literature. Validation methods for the control performance vary from computer simulations to clinical tests on human patients. A number of reports of clinical success support the feasibility of advanced control systems in this problem. Issues on control systems in the clinical environment are also discussed.

Closed-loop control of blood pressure, ventilation, and anesthesia delivery

Closed-loop control systems have been in use for over 4,000 years, yet applications in medicine have developed only recently. When compared with manual control, closed-loop controllers for blood pressure, ventilation, and anesthesia delivery provide more rapid and more precise control of mean pressure, end-tidal CO2, and end-tidal anesthetic concentrations. Closed-loop control systems perform better in almost all situations. It must be remembered however, that the best anesthesiologist may perform better than the controller, particularly in his ability to anticipate clinical events which effect control. Although the convenience, precision of control, and immunity to distractions are reason enough to further pursue their development, their final application to clinical care will depend on the inclusion of appropriate safeguards and supervisory software algorithms to protect the systems from failure.

Fundamentals of feedback control applied to microcomputer instrumentation design

Feedback control is widely used in applications which range from simple control of room temperature to very sophisticated control of space flight. This paper describes some fundamentals of feedback control as they apply specifically to microcomputer based medical devices. A classical controller is described in its analog and digital implementations. Reference is made to methods for adjusting or tuning the controller for specific applications. Successful applications of adaptive or self-tuning control are discussed. Examples of feedback control include systems to control arterial blood pressure by the infusion of sodium nitroprusside, systems to control arterial carbon dioxide concentration by mechanical ventilation and systems to control depth of anesthesia by controlled anesthesia delivery.

Evaluation of two adaptive sodium nitroprusside control algorithms

Computer control of sodium nitroprusside infusion may be safer and provide better control of arterial blood pressure than is achieved with manual control. In a series of test maneuvers in 20 mongrel dogs, the performance of two adaptive control algorithms (controllers) was compared and their safety tested. The controllers were set to infuse sodium nitroprusside to decrease mean arterial pressure and maintain it 20 to 30 mm Hg below the control pressure. Then, sequentially, the right atrium was paced to simulate a supraventricular tachydysrhythmia, the right ventricle was intermittently paced to simulate ventricular extrasystoles, large tidal volumes were given to simulate a respiratory-therapy maneuver, the catheter was clamped to simulate clotting, an air bubble was introduced, and the infused sodium nitroprusside concentrations were either doubled or halved. Next, 500 ml of blood was drawn. Then, in sequence, positive end-expiratory pressure was applied, the right atrium was paced, and large tidal volume breaths were given to cause the blood pressure to fluctuate. When the controllers were turned on, mean arterial pressure reached the set point and remained within 5 mm Hg of the target pressure after 8.6 +/- 0.9 minutes (mean +/- SEM). The controllers properly handled the differences in sodium nitroprusside sensitivity and the catastrophic challenges presented in the experiments. When the animals were not being disturbed, stability was maintained and the blood pressure was kept well within 5 mm Hg of the desired pressure. The controllers rejected all invalid pressure signals during testing.(ABSTRACT TRUNCATED AT 250 WORDS)