Reed M. Gardner

The fast flush test measures the dynamic response of the entire blood pressure monitoring system

The fast flush test (FT) is the only test that allows clinicians to determine in vivo the natural frequency (fn) and damping coefficient (zeta) of an invasive blood pressure monitoring system. The underlying assumption to the validity of the FT is that it activates the whole system including the distal catheter. We devised an in vitro model of a typical invasive blood pressure monitoring system to determine whether this assumption was true. The model consisted of a conventional transducer with a flush device attached to various lengths of connecting tubing (91.4, 182.9, and 274.3 cm) terminated by four different diameter catheters (5.1 cm 14 G, 16 G, 18 G, and 20 G). A microtipped transducer catheter was inserted into the distal catheter tubing system. A FT was performed and the fn and zeta were recorded from the conventional transducer and simultaneously from the microtipped transducer catheter. Similar studies were conducted using the ROSE damping device as well as with systems including 0.1 ml of air near the conventional transducer. These studies utilized 18- and 20-G catheters with each of the three lengths of connecting tubing. All measurements of fn and zeta at the proximal conventional transducer were identical to those measurements as recorded by the distal microtipped transducer catheter. We conclude that the FT activates the whole monitoring system and that fn and zeta are the same throughout the system including the distal catheter.

Perspectives on Development of IEEE 1073: The Medical Information Bus (MIB) Standard

Automated data capture from bedside patient medical devices is now possible using a new Institute of Electrical and Electronic Engineering (IEEE) and American National Standards Institute (ANSI) Medical Information Bus (MIB) data communications standard (IEEE 1073). The first two standard documents, IEEE 1073.3.1 (Transportation Profile) and IEEE 1073.4.1 (Physical Layer), define the hardware protocol for bedside device communications. With the above noted IEEE MIB standards in place, hospitals can now start designing customized applications for acquiring data from bedside devices such as bedside monitors, IV pumps, ventilators, etc. for multiple purposes. The hardware ‘plug and play’ features of the MIB will enable nurses and physicians to establish communications with these devices simply and conveniently by plugging them into a bedside data connector. No other action will be necessary to establish identification of the device or communications with the device. Presently to connect bedside devices, technical help from hardware and software experts are required to establish such communications links. As a result of standardization of communications, it will be easy to establish a highly mobile network of bedside devices and more promptly and efficiently collect patient related data. Collection of data automatically should lead to the design of new medical computing applications that will tie in directly with the emerging mission and operations of hospitals. The MIB will permit acquisition of patient data more efficiently with greater accuracy, more completeness and more promptly. The above noted features are all essential to the development of computerized treatment protocols and should lead to improved quality of patient care. This manuscript provides the rational and historical overview of the development of the MIB standard.

Integrating computerized anesthesia charting into a hospital information system.

Background: Systems for computerization of anesthesia records have typically been ‘stand-alone’ computers many times connected to monitoring devices in the operating theater. A system was developed and tested at LDS Hospital in Salt Lake City, Utah, USA that was an integral part of the Health Evaluation through Logical Processing (HELP) hospiial information system.Methods: The system was evaluated using time and motion studies to assess impact of the system on the anesthesiologists use of time, an assessment for completeness of the anesthesia record was conducted, and a questionnaire was used to assess anesthesiologists attitudes. Timing studies were performed on 44 surgical cases before computerization and 41 surgical cases after computerization. For both before and after computerization, about 80% of procedures were D&C, vaginal hysterectomy, laparoscopy, tubal ligation, or A&P repair.Results: The study showed a major reduction in time required for charting from 20.4% to 13.4% which was statistically significant (p=0.0001). Other significant factors were a reduction in the time spent scanning the entire area which dropped from 10.5% to 5.6% (p=0.001), patient preparation time increased from 10.1% to 13.1% (p=0.02), the time spent arranging equipment increased from 6.4% to 8.1%, and the average time spent on non-anesthesia activities increased from 6.3% to 11.3%. The computerized anesthesia record was more legible, and complete than the manual record. The overall assessment of computer charting by anesthesiologists questionnaire was positive. The computerized anesthesia charting was preferred by the anesthesiologists, who, after one or two training sessions, used the system on their own.Conclusions: It appears that having a computerized anesthesia charting system that is an integral part of a hospital information system not only saves anesthesiologists charting time, but also improves the quality of the record and was well accepted by busy private practive anesthesiologists.

Equivalence of fast flush and square wave testing of blood pressure monitoring systems

Background. The accurate recording of intraarterial pressure depends upon an appropriate dynamic response of the monitoring system. Generation of a square wave (SW) at the catheter tip is the engineering andin vitro laboratory gold standard. Fast flush (FF) testing is the clinical test of choice. Results from these two test methods have been assumed equal but have not been empirically confirmed.Methods. We studied three different 5.1 cm catheter sizes (16G, 18G, 20G Becton Dickinson, Sandy, UT) attached to three different lengths of arterial pressure tubing (36 in, 91.4 cm; 72 in, 182.9 cm; 108 in, 274.3 cm). An arterial recording system was assembled in the standard fashion by attaching a catheter to arterial pressure tubing, which was attached to a transducer (TXX-R, Ohmeda, formerly Viggo-Spectramed, Oxnard, CA) whose signal was recorded by a strip chart recorder (Gould 2400, Rolling Meadows, IL). The system was attached to a pressurized saline flush. The catheter tip was inserted into one port of a pressure generator. With the other port of the pressure generator open to atmosphere, FF tests were performed by activating the flush device of the transducer. Subsequent step response signals from the FF tests were then recorded from which natural frequency (fn) and damping coefficient (ζ) were calculated. Next, square waves were generated by closing the port that was open to atmosphere and attaching a signal generator to a pressure generator. Square waves so generated were recorded as described above and natural frequency and damping coefficients calculated. These procedures were repeated after 0.05 cc of air was introduced in the transducer and repeated again in a system containing a damping device (R.O.S.E., Resonant OverShoot Eliminator, Viggo-Spectramed, Oxnard, CA).Results. There was no significant difference between fn and ζ as calculated from the step response generated from the FF test versus fn and ζ as calculated from the square wave (SW) test in systems without air. However, in systems containing air, fn by FF testing was always less than fn by SW testing for all catheter sizes and extension tubing lengths (p < 0.05). Damping was also always greater by FF testing than by SW testing in systems with air for all catheter sizes and extension tubing lengths (p < 0.05). The R.O.S.E device created marked qualitative differences, although exact fn and ζ could not be quantified.Conclusions. For the characterization of dynamic response of invasive blood pressure monitoring systems, the FF test and SW test yield identical results. However, under certain conditions — air, R.O.S.E device — dynamic response as measured by FF testing was not equivalent to dynamic response as measured by the gold standard — the SW test. Specifically, small amounts of air in fluid-filled invasive blood pressure monitoring systems cause a slightly worse dynamic response as measured by FF testing versus the laboratory gold standard — the SW test.

Decision support systems in critical care

Modern critical care is characterized by the collection of large volumes of data and the making of urgent patient care decisions. The two do not necessarily go together easily. For many years, the hope has been that ICU data management systems would play a meaningful role in ICU decision support. These hopes now have a basis in fact, and this book details the history, methodology, current status and future prospects for critical care decision support systems. By focusing on real and operational systems, the book demonstrates the importance of integrating data from diverse clinical data sources; the keys to implementing clinically usable systems; the pitfalls to avoid in implementation; and the development of effective evaluation methods.

The HELP System Development Tools

The HELP (Health Evaluation Through Logical Processing) system, developed at the LDS Hospital and University of Utah in Salt Lake City, is a complete hospital information system (HIS) that supports not only traditional HIS functions, but routinely implements decision-making applications for clinical care. The following list enumerates the clinical applications that are currently available on the HELP system: Admit/Discharge/Transfer Order Entry/Charge Capture Medical Records Intensive-Care Unit Automation Nursing Charting/Care Plans/Acuity Radiology Surgery Scheduling/Management Laboratory Integration/Pathology Microbiology Alerting/Infectious Disease Pharmacy Laboratory Alerting Quality of Care Blood Gas Analysis Pulmonary Function Laboratory Physician Remote Access Respiratory Care Cardiology—ECG, Imaging, Catheterization Laboratory Obstetrics/Delivery Patient History

Medical Information Bus usage for automated IV Pump data acquisition: Evaluation of usage patterns

Objective: To identify factors which influence the choice of nurses to use automated collection of IV pump data from a prototype Medical Information Bus. Design: Observational study for a duration of three and one-half months. Setting: Four intensive care units, each with different missions, in an adult hospital. Subjects: One hundred fifty-eight registered nurses including both full and part time. Measurements and Main Results: Data were collected from the hospital information system about infusion orders including the type of medication, the number of rate changes, the method of documenting rate changes and the infusion methods. The method of documentation for infusion rate changes was defined as either automated, using a prototype Medical Information Bus (MIB), or manual, using the keyboard at a bedside computer terminal. The method of infusion was defined as either straight gravity feed without an IV pump (‘no pump’), infusion using a pump but without connection to the hospital information system (‘pump only’) and infusion using a pump which was connected to the hospital information system using a prototype Medical Information Bus (‘automated’). A total of 22,199 rate changes were documented during the study period and of those, 22,055 (99.35%) used the ‘automated’ method. Medications with the highest average rate change per single container were; Nitroprusside Sodium (9.50), Epinephrine (9.08) and Epoprostenol (7.50). Conclusions: The nurses used automated IV pump data acquisition with medications which required frequent rate changes.

Portable computers used for respiratory care charting

We studied the feasibility of using a portable lap computer (PLC) for bedside documentation of respiratory care procedures. Three Radio Shack TRS-80 Model 100 (PLCs) were used to capture and transfer the charting by phone into the hospital information system (HIS). Charting on the PLC could be done anywhere at the convenience of the therapist. Transferring data from the PLC to the HIS could be accomplished from any patient room, since all had phone jacks. Once information was entered into the HIS, it became immediately available for review on all nursing station terminals. A 39-day study of 5,019 entries was conducted using 12 therapists of whom 6 were randomly selected to carry PLCs and the other 6 used conventional ward terminals. We found that: 1) There was no statistically significant difference between PLC and nursing terminal entry in productivity or promptness of reporting; 2) Ward terminals were generally available for entry; 3) Cost, maintenance, initial training required, and therapist preference favored ward entry. We conclude that a PLC can be used in a clinical setting as a means of collecting and reporting data from the bedside, and as an input device to a larger computer system, but offers considerable disadvantages in comparison to entry at conventional terminals on the HIS if they are readily accessible.

The Future of Computerized Decision Support in Critical Care

As we write this final chapter, there is a foot of new snow on the ground in R.G.’s backyard in Salt Lake City, and the snow continues to fall. Last night three local television weather forecasters predicted we would only have two inches of snow, and all they had to do was predict one day into the future! With some trepidation, and without the equivalent of weather satellites and 40 years experience with forecasting, the authors will try to predict the future of computers and decision support systems in critical care. Our projections are based on two decades of experience and a generally optimistic outlook. We believe that seven broad areas will determine the pace of the future of computerized decision support in critical care: 1. Human, cultural, and sociological issues relating to how computers will be used in the intensive care unit (ICU). 2. Standardization in medicine and the ability to share medical knowledge will be essential. 3. Expanded medical knowledge will lead to better patient care. 4. Hardware and software will continue to advance at a rapid rate. 5. Data acquisition methods and instrumentation will provide more accurate, timely, and less expensive measurements. 6. Sharing of computer and clinical knowledge in computer form will become common and encouraged by government and the clinical community. 7. Better methods for prognostic decision-making will enable medical practitioners and society to make better ethical decisions about health care.

Organizational Vision and Strategic Directions

In the past, the management of technology resources provoked organizational debate and discussion. Yet in a surprising number of cases there was little or no integration or coordination of the informatics strategies with the overall organizational strategies. The informatics strategies—if explicitly defined at all—were set in a kind of organizational vacuum, resulting in considerable suboptimization. Today’s focus is the management of integrated technologies throughout the organization as a source of sustainable competitive advantage. How, then, does an organization determine its strategic technological direction to further that quest?