Patient centric identification and association.

Increased technological complexity of medical devices and systems coupled with increased workloads and reduced staffing, have created difficulties and discontinuities in the management of patient information. These issues have directly impacted and contributed to a rise in equipment-related errors, patient dissatisfaction, a potential for patient injury and resulting overall increased concern for patient safety. In response these concerns a variety of new devices, systems and applications have been developed to share information, provide cross checks along with verified delivery of critical information to the point of care. These applications include biomedical information systems, medication administration, sample collection, and electronic medical records. The deployment of these new integrated and networked devices, systems and applications are dependent on an accurate and consistent patient identification and association methodology which dynamically manages the relationship between patients, staff and equipment. Since the association information is common to many applications and utilizes a variety of technologies, (i.e. active and passive radio frequency identification (RFID), barcodes, etc.) an institutional approach is necessary to mange these processes in a consistent manor utilizing a common set of identification hardware. Implementation of a "Patient Centric Identification and Association Platform" represents a significant advance in the management of clinical patient information. The implementation of a Biomedical Device Information Network at Memorial Sloan-Kettering Cancer Center (MSKCC) integrates the identification and association of patients with devices and care providers and provides the methodologies to manage alarms, providing the ability to filter low priority or nuisance alarms. This implementation enables critical information to be distributed directly to care providers utilizing dedicated communications devices. Patient Centric Identification and Association is the enabling technology providing precise identification and association establishing an enhanced environment of care, increased patient safety, and a clear proactive response to the regulatory requirements of the Joint Commission (JCAHO) national patient safety initiatives.

Design of an enterprise-wide physiological and clinical data solution.

The deployment of new wireless and networked technology and advanced clinical applications has significantly increased the quality and the quantity of patient diagnostic and monitoring information throughout the patient care environment. Coupled with increasing workloads and reduced staffing, the difficulties in effectively prioritizing and handling this information have resulted in a rise in equipment-related errors, patient dissatisfaction, a potential for patient injury, and an increasing overall concern for patient safety. Concerns about this trend have prompted the Joint Commission to established seven patient safety initiatives geared to the patient environment of care, establishing methodologies and protocols to reduce the probability of errors, and to provide an enhanced level of communications. Planned deployment of advanced medical devices and supporting technologies coupled with our existing wired/wireless network infrastructure, need to consider the potential integrating clinical device, onto a unified network infrastructure providing advanced capabilities to share and effectively manage this key patient clinical information. Implementation of a biomedical device information network represents a significant advance in the management of clinical patient information, and enables device data, specifically critical patient alarms to be shared, coordinated, prioritized and sent directly to specific assigned care providers. The care giver utilizing a common hands-free wireless device can receive a prioritized audible (or a simulated voice) alarm message and utilize this same device for directed staff-to-staff or staff-to-patient communication. The Biomedical Information Network implementation identifies or associates patients with devices and consequently critical alarms, filters low priority or nuisance alarms, and eliminates the need for multiple costly communication devices. This implementation establishes an enhanced environment of care, providing increased patient safety, and a clear proactive response to the national patient safety initiatives.

Application of RFID in an integrated healthcare environment.

Radio Frequency Identification (RFID) is an evolving technology that can utilize its capabilities within a healthcare environment to locate and track staff, equipment, and patients. RFID has the potential to significantly improve operations by actively monitoring asset flow through an organization and enabling this data to be analyzed for process improvement. It can also help to provide validation to existing process improvement initiatives set forth by an institution. Furthermore, RFID can be integrated into other operations including patient safety, clinical operations, billing, and theft prevention.

Development and implementation of a biomedical information network.

Once the requirement for a biomedical information network has been articulated, the process of development and implementation can then be approached. Although the general architecture of such a system may appear to be self evident, there are careful design considerations that will allow the network to be robust and achieve increased levels of functionality as additional systems come on-line and become integrated into the network. As of this writing, there are few interoperability standards between the various medical systems that comprise the desired network. We have chosen the Emergin Orchestrator product (Boca Raton, Fl) as the vehicle for integrating these systems. The major design and implementation tasks include defining the basic information architecture, assessing the performance of the existing IT infrastructure, and understanding the native capabilities and limitations of each system involved in the network.

Determination of metabolic monitor errors and precision under clinical conditions.

BACKGROUND & AIMS: Metabolic monitoring devices used in the critical care setting are subject to a range of conditions that may compromise their accuracy. We sought to investigate the error and precision of the Deltatrac metabolic monitor under these conditions. METHODS: A modified version of the funnel burner, described by Miodownik et al. (8), was ventilated by a mechanical ventilator. This was used to examine the performance of the Deltatrac metabolic monitor over a wide range of inspired oxygen concentrations, minute ventilation, and positive end expiratory pressure at different levels of oxygen consumption and carbon dioxide production. RESULTS: The Deltatrac measured V(O(2)) with a mean error+/-precision of 9.4%+/-19.5% (range, 9.3%+/-1.9%-72.6%+/-13.6%). The mean V(CO(2)) error+/-precision was 1.2%+/-3.1% (range-2.0%+/-1.2%-5.4%+/-3.1%). Error was significantly affected by oxygen concentration and minute ventilation but was largely independent of positive and expiratory pressure. CONCLUSIONS: The methodology of Miodownik et al. permits the expression of metabolic device errors over a wide range of simulated clinical conditions.

System of automated gas-exchange analysis for the investigation of metabolic processes.

Conventional gas-exchange instruments are confined to the measurement of O(2) consumption (VO(2)) and CO(2) production (VCO(2)) and are subject to a variety of errors. This handicaps the performance of these devices at inspired O(2) fraction (FI(O(2))) > 0.40 and limits their applicability to indirect calorimetry only. We describe a device based on the automation of the Douglas bag technique that is capable of making continuous gas-exchange measurements of multiple species over a broad range of experimental conditions. This system is validated by using a quantitative methanol-burning lung model modified to provide reproducible (13)CO(2) production. The average error for VO(2) and VCO(2) over the FI(O(2)) range of 0.21-0.8. is 2.4 and 0.8%, respectively. The instrument is capable of determining the differential atom% volume of known references of (13)CO(2) to within 3.4%. This device reduces the sources of error that thwart other instruments at FI(O(2)) > 0. 40 and demonstrates the capacity to explore other expressions of metabolic activity in exhaled gases related to the excretion of (13)CO(2).

Quantitative methanol-burning lung model for validating gas-exchange measurements over wide ranges of FIO2.

The methanol-burning lung model has been used as a technique for generating a predictable ratio of carbon dioxide production (VCO2) to oxygen consumption (VO2) or respiratory quotient (RQ). Although an accurate RQ can be generated, quantitatively predictable and adjustable VO2 and VCO2 cannot be generated. We describe a new burner device in which the combustion rate of methanol is always equal to the infusion rate of fuel over an extended range of O2 concentrations. This permits the assembly of a methanol-burning lung model that is usable with O2 concentrations up to 100% and provides continuously adjustable and quantitative VO2 (69-1,525 ml/min) and VCO2 (46-1,016 ml/min) at a RQ of 0.667.

Utilization of intraoperative electroneurography to understand the innervation of the trapezius muscle.

The radical neck dissection is an operation for the management of lymph node metastases from primary sites involving the oral cavity, larynx, and other areas of the head and neck. In this procedure, the spinal accessory nerve is removed along with other structures. In modified neck dissection the spinal accessory nerve is preserved. Patients undergoing the modified neck dissection have had variable functional outcomes from little or no pain or disability, to significant muscle dysfunction. Our group hypothesized that patients with good functional outcomes following modified neck dissection may have had motor contributions from C2, C3, or C4 branches, while those with less favorable outcomes did not. To demonstrate the presence of motor input and its significance both from the spinal accessory nerve and the branches of the cervical plexus, we utilized intraoperative electroneurography. We find that although there is motor contribution from C2, C3, and C4 to the trapezius muscle, it was not consistent or significant.

A birdcage resonator for intracavitary MR imaging.

An intracavitary probe for magnetic resonance imaging of the pelvis has been developed that takes advantage of the "inside-out" spatial characteristics of a birdcage resonator. The probe consists of an eight-leg, birdcage resonator in a low-pass configuration operating in receive-only mode. The resonator circuit is mounted on a solid rod, is encased in Teflon, and has been used to obtain detailed images of pelvic anatomy in a male canine. The approximate cylindrical symmetry of the external sensitivity profile of this type of circuit, employed in an intracavitary application, demonstrates the potential superiority of this type of probe design over single-loop intracavitary coils. Axial, coronal, and sagittal MR images, obtained with 8 and 16 cm fields of view, are presented to illustrate the advantages of this type of intracavitary probe compared with conventional body-coil images. The prototype described in this report has been designed for clinical use in human subjects and is currently undergoing testing to determine its efficacy in the evaluation of rectal, prostate, and gynecologic pathology.

Effect of midazolam on the auditory event-related potential: measures of selective attention.

To elucidate the delayed effects of midazolam, we assessed electrophysiologic and motor responses by measuring auditory event-related potentials and a button-press reaction time response in 10 normal volunteers (aged 25-36 yr). Fifty minutes after intravenous infusion of 0.07 mg/kg of midazolam, subjects were mildly sedated, oriented, and readily responsive to verbal commands. To obtain ERPs, frequent tones (85%: 1000 Hz) and rare tones (15%: 2500 Hz) were presented at intervals of 1.5 s. Electroencephalographic signals were collected from FZ, CZ, and PZ for 1000 ms after stimulus presentation until 40 artifact-free rare-tone responses were obtained (average time, 6 min). Peak-to-peak amplitudes and latencies for N2, P3, and the subsequent negative slow wave (N3) were averaged within condition and were analyzed by repeated measures analysis of variance. After midazolam infusion, there was a 50% decrease in amplitude of P3 in response to target tones (P less than 0.006), whereas N3 latency increased by 40 ms (P less than 0.05). Event-related potential amplitudes were still significantly larger to rare (target) stimuli (P less than 0.003) after midazolam infusion. Although reaction time increased by 70 ms (P = 0.031), performance accuracy remained unchanged. Self-ratings of sleepiness and concentration show that a significant sedation effect was still present 50 min after infusion. Although routine clinical examination may be normal, full recovery from the effects of a typical intravenous dose of midazolam requires more than 50 min. The potential for adverse drug interaction, particularly with narcotics, is still present at this time.

Frequency response of the peripheral sampling sites of a clinical mass spectrometer.

Mass spectrometers are used in ICUs and ORs to measure the concentration of medical and anesthetic gases gathered from multiple sites. This investigation was designed to determine the accuracy of a clinical system, which included 12 ICU bedside stations monitored by a medical mass spectrometer (Perkin-Elmer RMS III, Pomona, CA). Each site station was connected to the analyzing unit via two Teflon tubes, one permanently installed, 30-m long, and the second disposable, 2.4-m long. A gas mixture containing 95% O2 and 5% CO2, alternating with room air, was delivered to a solenoid valve and from there to the connecting tubes. Gas flow-rate, delay time, rise time, and peak and trough concentrations were determined for each gas at solenoid cycling frequencies of 25, 50, and 100/min. After the first set of measurements, the 30-m tubes were thoroughly cleaned and all measurements repeated. In addition, the authors also measured CO2 delay and rise times when the gas was delivered to the mass spectrometer through an unused 30-m tube or a new 2.4-m tube. Gas flow-rate increased from 143 +/- 12 ml/min (mean +/- SD) to 238 +/- 9 ml/min after the tubes were cleaned. Delay time was identical for all gases at all solenoid cycling rates but decreased significantly (P less than 0.05), from 11.5 +/- 0.3 to 4.8 +/- 0.7 s after the ceiling tubes were cleaned. As solenoid valve rate increased, the difference between measured and actual gas concentration increased. The lowest accuracy was 63.6 +/- 2.1%, for CO2 at 100 cycles/min.(ABSTRACT TRUNCATED AT 250 WORDS)

Design of apparatus for precise x-ray dose chamber calibrations.

An apparatus for precision calibration of ion chambers in the x-ray region from 16 to 320 kV is described. The development of a fast-acting shutter with "opening" and "closing" times of less than 3-ms eliminates the requirement for operating time corrections. Controls from outside the radiation room permit changing x-ray filters and alternately positioning both test and standard ion chambers in the x-ray beam. Thus, the remote controls eliminate the need to enter the x-ray room in the course of a series of calibrations. The potential advantages resulting from the capabilities of this apparatus are described in this Technical Report.

Doubly tuned solenoidal resonators for small animal imaging and spectroscopy at 1.5 Tesla.

The design and construction of solenoidal resonators for use with small animals in a 1.5-Tesla clinical imaging system are described. The coils have been designed to exploit the B1 distributions of two resonant modes of a four-turn solenoid whose windings are in parallel. Both singly and doubly tuned versions have been constructed. 1H images of normal and pathologic anatomy in mice and rats as well as a 31P spectrum of a Walker 256 rat sarcoma are presented. A primary advantage of this design is that the coils are easy to build and implement while providing the necessary sensitivity to allow high quality images to be obtained with no changes to the hardware or software of the clinical unit.

An automated mechanism for protection of mass spectrometry sampling tubing.

The usefulness of medical mass spectrometers in intensive care units can be limited by too frequent obstruction of the tubing that transports gases from the patients to the analyzing unit. To overcome this problem, we developed an automated system consisting of an infrared light sensor and a three-way valve. One port of the three-way valve connects to 2.4-m disposable tubing that collects gases from the patient's airway. The second port is connected to a mass spectrometer analyzing unit through 30-m permanently installed tubing. The third port is connected to a pressurized oxygen source. An infrared light sensor is placed on the shorter tubing, between the patient and the three-way valve. When increased optical density is detected, due to entrainment of respiratory secretions, the three-way valve is activated. Gas flow is closed between the patient and the mass spectrometer and opened between the pressurized oxygen source and patient tubing to flush its contents. During the six years that the protection system has been in use, the frequency with which the disposable gas collection tubing is changed has been halved. Furthermore, periodic tests of delay and response times, performed at each bedside station, indicate that permanent connection tubing only needed cleaning at 2- to 3-year intervals. The system has decreased the cost of operating our mass spectrometers while also reducing periods of unavailability due to equipment failure.

Capnography in mechanically ventilated patients.

Capnography, the science of CO2 waveforms analysis, can play a role in the management of mechanically ventilated patients. Mass spectrometers are the devices most commonly used to collect sequentially and examine CO2 waveforms from multiple patients in the ICU or operating rooms. We present here a review of some clinical and technical problems, which may be resolved efficiently and expeditiously through the use of mass spectrometry and capnography. Mechanical failures, especially those that lead to rebreathing of exhaled gases, can be readily detected. The patient's progress during weaning and the consequences of changes in mechanical assistance can be virtually and noninvasively determined. An expanded role of capnography in mechanically ventilated patients can increase the use of mass spectrometers in the ICU.

Indirect calorimetry in the mechanically ventilated patient.

We used indirect calorimetry to measure oxygen consumption (VO2) and carbon dioxide production in 29 mechanically ventilated patients. These data were compared to VO2 measured simultaneously by a standard thermodilution technique. A good correlation was demonstrated between the methods, but VO2 measured by indirect calorimetry was 15% higher than VO2 measured by thermodilution.

High-frequency jet ventilation: technical implications.

A variety of technical decisions are required for the proper selection and safe and efficacious application of high-frequency jet ventilation (HFJV). Criteria for analyzing the performance of an HFJV system are presented, along with discussions of some of the more common respiratory measurements and their applicability to HFJV.

Pneumatic-to-electrical analog for high-frequency jet ventilation of disrupted airways.

A pneumatic-to-electrical circuit analog is used to describe 2 separate mechanisms by which high-frequency jet ventilators sustain ventilation and oxygenation in the presence of large airway disruptions. The frequency-dependent mechanism is based on variations in the pneumatic equivalent to capacitive reactance. The pressure-dependent mechanism models lung defects on a voltage-controlled resistor. The electrical circuit model is also used to explain the factors leading to gas trapping and inadvertent positive end-expiratory pressure during high-frequency jet ventilation.

Experimental evaluation of high-frequency jet ventilation.

The consensus of available studies indicates that high-frequency jet ventilation (HFJV) can adequately ventilate animals in respiratory failure, although a clear superiority to volume-cycled ventilation (VCV) cannot be established. HFJV is probably useful in the presence of airway disruption and in tracheal or pulmonary surgery. Clinical trials and additional bench and animal studies must be performed, to reach a full understanding of the potential benefits of this technique.