Optimization of Post-Surgery Wake Up Time Providing Adequate Analgesia

What is the best drug concentration during anesthesia? We are creating algorithms to minimize pain and shorten wake up time after surgery. This will be used by anesthesiologist during surgery to continuously provide optimal drug cocktails with surgery and patient specificity

An Accurate Metabolic Simulator for Indirect Calorimetry System Validation

A metabolic simulator capable of simulation of respiratory oxygen consumption (VO2) and carbon dioxide production (VCO2) for validation of indirect calorimetry systems is described. The metabolic simulator adds/removes respiratory gases by way of mass flow controllers to/from a physiologically realistic lung simulator (Michigan Instruments Inc. Training/Test Lung). The metabolic simulator and Michigan Instruments Training/Test Lung in combination are capable of simulating a wide range of metabolic and physiologic lung conditions. Simulation of VCO2 is achieved by adding controlled amounts of carbon dioxide to the Training/Test Lung every (mechanical ventilator delivered) breath cycle. VO2 simulation consists of adding controlled amounts of nitrogen and removing controlled amounts of inspiratory gas from the Training/Test Lung every breath. Real time monitoring of ventilation parameters is obtained from a Novametrix Cosmo+ respiratory profile monitor and control of gas flow through the simulator is achieved by way of a programmed IBM personal computer

CONTROL OF END-TIDAL HALOTHANE CONCENTRATION: Part A: Anaesthesia Breathing System and Feedback Control of Gas Delivery

Conventional anaesthetic breathing systems are not designed to control end-tidal gas concentrations, nor can they be used to measure accurately the uptake of oxygen or of anaesthetic agent. We built and tested a leak-tight closed-loop anaesthetic breathing system with low solubility to volatile anaesthetic agents and with efficient gas mixing. The system included a water-sealed spirometer, a small carbon dioxide absorber, a coaxial tube to the patient a circulating pump and feedback controllers for system volume and anaesthetic concentration. Feedback control was implemented to adjust and control automatically the end-tidal anaesthetic concentration and the volume of the system with oxygen supplied through a mass flow controller and with halothane supplied by a titrating syringe. Controller gains, as a function of body weight, were found using a nine-compartment tissue uptake model. Stability was maintained with ±50% changes in alveolar ventilation and cardiac output. During subsequent investigations in an animal model, arterial, mixed venous and cerebral venous blood halothane concentrations were measured to show that the feedback-controlled halothane induction was optimized. We conclude that feedback control appears to be clinically applicable for adjusting the end-tidal Concentration and system volume to provide a rapid and optimized induction of anaesthesi

CONTROL OF END-TIDAL HALOTHANE CONCENTRATION: Part B: Verification in Dogs

Conventional anaesthetic techniques do not allow for the automatic control of end-tidal halothane concentration and, therefore, brain concentration cannot be predicted. In this study, eight dogs were ventilated with halothane in oxygen using a new closed-loop anaesthetic breathing system which provided a constant end-tidal concentration. During the first 60 min the end-tidal concentration was maintained at 0.87 vol% (1 MAC). Then followed 60 min of halothane wash-out and a further 120-min period of halothane at 1.74 vol% (2 MAC). Halothane concentrations were measured in the inspired and expired air, and in the arterial, cerebral venous and mixed venous blood. Haemodynamic and respiratory variables were measured. The system reached 95% of the target end-tidal concentration within 6 min without over-shooting. After 2 h of wash-in, significant gradients still persisted between end-tidal, arterial and cerebral venous blood concentrations. Measured uptake differed from theoretically calculated uptake by 18.3-57.6%, depending on the model used. Measured arterial and cerebral venous concentrations differed from theoretically calculated values by 7% and 17.5%, respectively. It was shown that the required end-tidal concentrations can be obtained rapidly and accurately, and that brain tissue concentrations can be predicted within certain limit

DETERMINATION OF THE PARTIAL PRESSURE OF HALOTHANE (OR ISOFLURANE) IN BLOOD

A gas chromatographic method is described for the direct quantitative determination of the partial pressure of halothane {or isoflurane) in blood as well as the blood-gas partition coefficient. A head space technique and a flame ionization detector were used. Standard blood was obtained by equilibrating patients' blood with known gas concentrations in a tonometer. Using an infra-red analyser to measure the halothane gas concentration in the tonometer and within the anaesthetic system allowed for the direct comparison of the partial pressure in blood to the partial pressure in the inspired gas. Technical problems associated with this procedure, and with comparable methods, are discusse

Optimization Methods to Minimize Emergence Time While Maintaining Adequate Post-Operative Analgesia

A rapid emergence from anesthesia combined with an extended duration of adequate analgesia is desired. Difficulties arise when trying to achieve a rapid emergence and provide adequate analgesia for procedures associated with moderate post operative pain. We propose to use pharmacokinetic (PK) and pharmacodynamic (PD) models with optimization techniques to determine anesthetic drugs ratios to improve post-anesthetic outcomes of emergence and analgesia. We hypothesize that optimized propofol, remifentanil, and fentanyl administrations will shorten emergence time and extend the period of adequate analgesia during patient recovery. Anesthesiologists administered a general anesthetic to 21 patients for laparoscopic procedures with propofol, remifentanil, and fentanyl according to their standard practice. The theoretical improvement provided by the optimization was measured by comparing the time differences between the control predictions and the optimized prediction of the TROR time and TRON time. In the control group the TROR was 10.2+-5.8 minutes (mean +- SD) and TRON was 3.5+-5.0 minutes after emergence. In the optimized group the TROR was 7.5+-2.2 minutes or 26% faster (p \u3c .001, paired t-test) and the TRON was 7.4 +-2.4 minutes or 88% longer (p \u3c .00001, t-test). Optimized administrations of propofol, remifentanil, and fentanyl resulted in a theoretically shorter emergence time and a longer period of adequate postoperative analgesia. The optimization algorithm shows potential for real-time clinical guidance in drug management

Relativistic Klystron Two-Beam Accelerator studies at the RTA test facility

A prototype rf power source based on the Relativistic Klystron Two- Beam Accelerator (RK-TBA) concept is being constructed at LBNL to study physics, engineering, and costing issues. The prototype, called RTA, is described and compared to a full scale design appropriate for driving the Next Linear Collider. Specific details of the induction core test and pulsed power system are presented. Details of the 1-MeV, 1.2-kA induction gun currently under construction are described

RK-TBA studies at the RTA test facility

Construction of a prototype RF power source based on the RK-TBA concept, called the RTA, has commenced at the Lawrence Berkeley National Laboratory. This prototype will be used to study physics, engineering, and costing issues involved in the application of the RK-TBA concept to linear colliders. The status of the prototype is presented, specifically the 1-MV, 1.2-kA induction electron gun and the pulsed power system that are in assembly. The RTA program theoretical effort, in addition to supporting the development of the prototype, has been studying optimization parameters for the application of the RK-TBA concept to higher-energy linear colliders. An overview of this work is presented. 1 fig

Evaluation of a Graphical Anesthesia Drug Display for Space Travel

As the frequency and duration of space travel increase, the potential need for emergency medical care in space grows, and with it the need for patient monitoring devices supporting therapeutic treatment. Providing emergency care to an injured astronaut may necessitate immediate surgery. During such events, the timely administration of anesthetic agents will need to be performed by someone who is not a formally trained anesthesiologist. The availability of usable real-time displays of intravenous anesthetic concentrations and effects could significantly enhance intraoperative clinical decision-making both in space and on earth. The effectiveness of the real-time anesthesia display on the management of total intravenous anesthesia was determined by 31 anesthesiologists participating in a simulation study. In the presence of the anesthesia drug display, clinicians maintained physiologic indicators such as blood pressure and heart rate closer to baseline levels. Participants also reported an increase in perceived performance when using the drug display. The results indicate that surgeries on earth and in orbit would benefit from the implementation of this display

Pulmonary Metaphor Design and Anesthesia Simulation Testing

Medical decision making is a crucial process to successfully treat a critical medical emergency. During an unexpected medical event, astronauts, like anesthesiologists, must react quickly in a complex environment. Tools, such as the pulmonary metaphor display, were created to aid the medical caregiver\u27s decision making process. The pulmonary metaphor display is designed to help the caregiver collect and integrate pulmonary data to provide a more accurate, quicker diagnosis and treatment. The following outline anesthesiology simulation study will provide the data to prove that the pulmonary metaphor display is beneficial to medical decision making