Evaluation of an adaptive, rule-based dosing algorithm to maintain therapeutic anticoagulation during atrial fibrillation ablation.

Background: Cerebral thromboembolism during atrial fibrillation (AF) ablation is an infrequent (0.17%) complication in part owing to strict adherence to intraprocedural anticoagulation. Failure to maintain therapeutic anticoagulation can lead to an increase in events, including silent cerebral ischemia. Objective: To evaluate a computerized, clinical decision support system (CDSS) to dose intraprocedural anticoagulation and determine if it leads to improved intraprocedural anticoagulation outcomes during AF ablation. Methods: The Digital Intern dosing algorithm is an adaptive, rule-based CDSS for heparin dosing. The initial dose is calculated from the patient's weight, baseline activated clotting time (ACT), and outpatient anticoagulant. Subsequent recommendations adapt based on individual patient ACT changes. Outcomes from 50 cases prior to algorithm introduction were compared to 139 cases using the algorithm. Results: Procedures using the dosing algorithm reached goal ACT (over 300 seconds) faster (17.6 ± 11.1 minutes vs 33.3 ± 23.6 minutes pre-algorithm, P < .001). ACTs fell below goal while in the LA (odds ratio 0.20 [0.10-0.39], P < .001) and rose above 400 seconds less frequently (odds ratio 0.21 [0.07-0.59], P = .003). System Usability Scale scores were excellent (96 ± 5, n = 7, score >80.3 excellent). Preprocedure anticoagulant, weight, baseline ACT, age, sex, and renal function were potential predictors of heparin dose to achieve ACT >300 seconds and final infusion rate. Conclusion: A heparin dosing CDSS based on rules and adaptation to individual patient response improved maintenance of therapeutic ACT during AF ablation and was rated highly by nurses for usability.

Clinicians' Perceptions of an Artificial Intelligence-Based Blood Utilization Calculator: Qualitative Exploratory Study.

BACKGROUND: According to the US Food and Drug Administration Center for Biologics Evaluation and Research, health care systems have been experiencing blood transfusion overuse. To minimize the overuse of blood product transfusions, a proprietary artificial intelligence (AI)-based blood utilization calculator (BUC) was developed and integrated into a US hospital's electronic health record. Despite the promising performance of the BUC, this technology remains underused in the clinical setting. OBJECTIVE: This study aims to explore how clinicians perceived this AI-based decision support system and, consequently, understand the factors hindering BUC use. METHODS: We interviewed 10 clinicians (BUC users) until the data saturation point was reached. The interviews were conducted over a web-based platform and were recorded. The audiovisual recordings were then anonymously transcribed verbatim. We used an inductive-deductive thematic analysis to analyze the transcripts, which involved applying predetermined themes to the data (deductive) and consecutively identifying new themes as they emerged in the data (inductive). RESULTS: We identified the following two themes: (1) workload and usability and (2) clinical decision-making. Clinicians acknowledged the ease of use and usefulness of the BUC for the general inpatient population. The clinicians also found the BUC to be useful in making decisions related to blood transfusion. However, some clinicians found the technology to be confusing due to inconsistent automation across different blood work processes. CONCLUSIONS: This study highlights that analytical efficacy alone does not ensure technology use or acceptance. The overall system's design, user perception, and users' knowledge of the technology are equally important and necessary (limitations, functionality, purpose, and scope). Therefore, the effective integration of AI-based decision support systems, such as the BUC, mandates multidisciplinary engagement, ensuring the adequate initial and recurrent training of AI users while maintaining high analytical efficacy and validity. As a final takeaway, the design of AI systems that are made to perform specific tasks must be self-explanatory, so that the users can easily understand how and when to use the technology. Using any technology on a population for whom it was not initially designed will hinder user perception and the technology's use.

Effect of risk, expectancy, and trust on clinicians' intent to use an artificial intelligence system -- Blood Utilization Calculator.

A gap exists between the capabilities of artificial intelligence (AI) technologies in healthcare and the extent to which clinicians are willing to adopt these systems. Our study addressed this gap by leveraging 'expectancy-value theory' and 'modified extended unified theory of acceptance and use of technology' to understand why clinicians may be willing or unwilling to adopt AI systems. The study looked at the 'expectancy,' 'trust,' and 'perceptions' of clinicians related to their intention of using an AI-based decision support system known as the Blood Utilization Calculator (BUC). The study used purposive sampling to recruit BUC users and administered a validated online survey from a large hospital system in the Midwest in 2021. The findings captured the significant effect of 'perceived risk' (negatively) and 'expectancy' (positively) on clinicians' 'trust' in BUC. 'Trust' was also found to mediate the relationship of 'perceived risk' and 'expectancy' with the 'intent to use BUC.' The study's findings established pathways for future research and have implications on factors influencing BUC use.

Electronic clinical decision support to facilitate a change in clinical practice: Small details can make or break success.

BACKGROUND: The use of electronic clinical decision support (CDS) is becoming common to change historically common clinical practices considered outdated by current guidelines. Preimplementation design of CDS tools is key to their success in changing clinical behaviors. Unfortunately, there are no established protocols for CDS tool development, and CDS failure can result from even small design flaws. This paper describes an example of a design oversight and how correction resulted in CDS success. STUDY DESIGN AND METHODS: We performed a retrospective review of compliance with a CDS tool to encourage the use of prothrombin complex concentrate over plasma transfusion for the emergent reversal of warfarin. We identified a potential design flaw, made the necessary modifications, and repeated the compliance review. RESULTS: After CDS, plasma orders declined by 150 units/mo; however, 48% of orders placed for non-warfarin coagulopathy were still for warfarin reversal. Hospital-wide, this noncompliance was 36% and was 80% in the emergency department. By simply relocating the qualifier "NOT on warfarin" from the end to the beginning of the order, noncompliance for warfarin reversal was reduced to 5% (P < .0001 by chi-square). CONCLUSIONS: The successful use of electronic clinical decision support in the electronic medical record can depend on optimal design. Missing even small design elements such as the positioning of key terms within the tool can result in an ineffective CDS. Important design strategies to avoid poor performance are discussed as they relate to the CDS tool we describe.

The blood utilization calculator, a target-based electronic decision support algorithm, increases the use of single-unit transfusions in a large academic medical center.

BACKGROUND: Electronic decision support has been used to reduce use of red blood cell (RBC) transfusion. With the goal of reducing transfusions, we modified our RBC orders to default to 1 unit. Next, we created a target-based algorithm, the blood utilization calculator or BUC, to calculate a dose in units, based on initial hemoglobin or hematocrit and weight. STUDY DESIGN AND METHODS: RBC orders defaulted to 1 unit in March 2016 and the BUC was implemented in July 2016. This gave three periods to compare old orders (before intervention), new orders (1-unit default), and the BUC period. A hospital dashboard that tracks blood product orders was queried to determine changes in single-unit transfusions between periods. Changes in transfusions were compared by analysis of variance. Acceptance of the BUC dosage recommendation was studied in both medical-based and surgical-based specialties. RESULTS: The number of single-unit transfusions showed significant increases after each of the two interventions studied from 247 ± 19 before interventions to 358 ± 19 and then to 445 ± 141-unit transfusions/month (p < 0.0001). The ratio of 1-unit to 2-unit transfusions increased from 0.72 to 1.67 (p < 0.0001) and we observed a 19% overall reduction in units transfused. The BUC recommendation was accepted in 49% of orders. CONCLUSIONS: One-unit default orders and implementation of the BUC resulted in a significant increase in the use of single-unit transfusions. Improvement in the rate of acceptance of the BUC recommendation should further increase the use of single-unit transfusions.

Outcomes of red blood cell transfusions prescribed in organ donors by the Digital Intern, an electronic decision support algorithm.

BACKGROUND: The Digital Intern (DI) is an electronic decision support tool for the management of organ donors. One algorithm determines the dose, in units of red blood cells to be transfused, based on hematocrit (Hct) thresholds and targets. The effectiveness of the transfusion dose calculated by the DI in terms of achieving the selected Hct target and the duration of the targeted dose is not known. STUDY DESIGN AND METHODS: This was a retrospective study to describe the outcomes of transfusions prescribed by the DI. Pre- and posttransfusion Hct levels were compared to define response and all posttransfusion Hct values were plotted to evaluate the duration of the prescribed dose. RESULTS: A total of 120 organ donors were studied and 22 donors had 28 transfusions (six were transfused twice). The transfused donors were a mix of trauma and medical admissions and brain death and cardiac death donors. The transfusion target of 24% Hct was attained in 96% of transfusions. The mean number of units transfused was 1.4 and the mean time from transfusion to procurement was 19.8 hours. There was a decline in Hct over time after transfusion in all but one case with a mean decline of 1.9% Hct over 13 hours. Six donors were transfused twice, likely due to a longer donor time period (41.7 hr vs. 27 hr). CONCLUSIONS: The DI provided transfusion dosing that achieved the desired threshold in the majority of organ donors transfused. Ongoing work focuses on application of this technology to transfusions in general patient populations.

A Novel Intracranial Pressure Readout Circuit for Passive Wireless LC Sensor.

We present a wide frequency range, low cost, wireless intracranial pressure monitoring system, which includes an implantable passive sensor and an external reader. The passive sensor consists of two spiral coils and transduces the pressure change to a resonant frequency shift. The external portable reader reads out the sensor's resonant frequency over a wide frequency range (35 MHz-2.7 GHz). We propose a novel circuit topology, which tracks the system's impedance and phase change at a high frequency with low-cost components. This circuit is very simple and reliable. A prototype has been developed, and measurement results demonstrate that the device achieves a suitable measurement distance (>2 cm), sufficient sample frequency (>6 Hz), fine resolution, and good measurement accuracy for medical practice. Responsivity of this prototype is 0.92 MHz/mmHg and resolution is 0.028 mmHg. COMSOL specific absorption rate simulation proves that this system is safe. Considerations to improve the device performance have been discussed, which include the size of antenna, the power radiation, the Analog-to-digital converter (ADC) choice, and the signal processing algorithm.

Invasive and noninvasive means of measuring intracranial pressure: a review.

Measurement of intracranial pressure (ICP) can be invaluable in the management of critically ill patients. Cerebrospinal fluid is produced by the choroid plexus in the brain ventricles (a set of communicating chambers), after which it circulates through the different ventricles and exits into the subarachnoid space around the brain, where it is reabsorbed into the venous system. If the fluid does not drain out of the brain or get reabsorbed, the ICP increases, which may lead to brain damage or death. ICP elevation accompanied by dilatation of the cerebral ventricles is termed hydrocephalus, whereas ICP elevation accompanied by normal or small ventricles is termed idiopathic intracranial hypertension. OBJECTIVE: We performed a comprehensive literature review on how to measure ICP invasively and noninvasively. APPROACH: This review discusses the advantages and disadvantages of current invasive and noninvasive approaches. MAIN RESULTS: Invasive methods remain the most accurate at measuring ICP, but they are prone to a variety of complications including infection, hemorrhage and neurological deficits. Ventricular catheters remain the gold standard but also carry the highest risk of complications, including difficult or incorrect placement. Direct telemetric intraparenchymal ICP monitoring devices are a good alternative. Noninvasive methods for measuring and evaluating ICP have been developed and classified in five broad categories, but have not been reliable enough to use on a routine basis. These methods include the fluid dynamic, ophthalmic, otic, and electrophysiologic methods, as well as magnetic resonance imaging, transcranial Doppler ultrasonography (TCD), cerebral blood flow velocity, near-infrared spectroscopy, transcranial time-of-flight, spontaneous venous pulsations, venous ophthalmodynamometry, optical coherence tomography of retina, optic nerve sheath diameter (ONSD) assessment, pupillometry constriction, sensing tympanic membrane displacement, analyzing otoacoustic emissions/acoustic measure, transcranial acoustic signals, visual-evoked potentials, electroencephalography, skull vibrations, brain tissue resonance and the jugular vein. SIGNIFICANCE: This review provides a current perspective of invasive and noninvasive ICP measurements, along with a sense of their relative strengths, drawbacks and areas for further improvement. At present, none of the noninvasive methods demonstrates sufficient accuracy and ease of use while allowing continuous monitoring in routine clinical use. However, they provide a realizable ICP measurement in specific patients especially when invasive monitoring is contraindicated or unavailable. Among all noninvasive ICP measurement methods, ONSD and TCD are attractive and may be useful in selected settings though they cannot be used as invasive ICP measurement substitutes. For a sufficiently accurate and universal continuous ICP monitoring method/device, future research and developments are needed to integrate further refinements of the existing methods, combine telemetric sensors and/or technologies, and validate large numbers of clinical studies on relevant patient populations.

Standardization of transfusion practice in organ donors using the Digital Intern, an electronic decision support algorithm.

BACKGROUND: Prospective clinical trials support restrictive thresholds for red blood cell (RBC) transfusion. Nonsurvivable donors are a major source of organs for transplantation. The Digital Intern (DI) is a computer algorithm to standardize donor care that includes a more restrictive transfusion threshold. The impact of standardized and restrictive RBC transfusion in organ donors, as determined by the DI, has not been reported. STUDY DESIGN AND METHODS: We conducted a retrospective cohort study to compare the transfusion practice of the DI (n = 100) to a historic group of physician-managed donors (n = 90). Transfusion rates, the number of units transfused, and pretransfusion laboratory values were compared between groups. The variability of these parameters was also compared between groups. Finally, the number of transplanted organs per donor in each group was compared. RESULTS: The mean time as a donor was 25.9 ± 15.2 hours and was not different between the groups. In the DI group 19% were transfused compared to 26% in the control group (p = 0.3). The number of units transfused was less in the DI group (1 unit vs. 2 units per transfusion, p = 0.03) and the pretransfusion hematocrit was lower in the DI group (23% vs. 27%, p = 0.01). The variability in the latter two parameters was significantly lower in the DI group. The number of transplanted organs per donor was similar in both groups (3.24 [DI] vs. 3.03 [control], p = 0.37). CONCLUSION: The DI provides a more standardization transfusion practice in organ donors and reduces blood use without compromising transplantable organs.

Use of High-Flow Continuous Renal Replacement Therapy with Citrate Anticoagulation to Control Intracranial Pressure by Maintaining Hypernatremia in a Patient with Acute Brain Injury and Renal Failure.

Traumatic brain injury and intracranial hypertension often require treatment to optimize patient outcome. There are a variety of complex medical conditions that can preclude standard approaches to the treatment of intracranial hypertension. We describe a case where a novel approach using continuous dialysis with trisodium citrate was used to optimize the outcome of a young male with acute renal failure and acute respiratory distress syndrome in the setting of acute traumatic brain injury.

Safety of a DVT chemoprophylaxis protocol following traumatic brain injury: a single center quality improvement initiative.

BACKGROUND: Venous thromboembolism (VTE) is a complication that affects approximately 30 % of moderate and severe traumatic brain injury (TBI) patients when pharmacologic prophylaxis is not used. Following TBI, specifically in the case of contusions, the safety and efficacy of pharmacologic thromboembolism prophylaxis (PTP) has been studied only in small sample sizes. In this study, we attempt to assess the safety and efficacy of a PTP protocol for TBI patients, as a quality improvement (QI) initiative, in the neuroscience intensive care unit (NSICU). METHODS: Between January 1st and December 31st, 2009, consecutive patients discharged from the University of Wisconsin NSICU after >a 48 h minimum stay were evaluated as part of a QI project. A protocol for the initiation of PTP was designed and implemented for NSICU patients. The protocol did not vary based on type of intracranial injury. The rate of VTE was reported as was heparin-induced thrombocytopenia and PTP-related expansion of intracranial hemorrhage (IH) requiring reoperation. The number of patients receiving PTP and the timing of therapy were tracked. Patients were excluded for persistent coagulopathy, other organ system bleeding (such as the gastrointestinal tract), or pregnancy. Faculty could opt out of the protocol without reason. Using the same criteria, patients discharged during the preceding 6 months, from July 1st to December 31st, 2008, were evaluated as controls as the PTP protocol was not in effect during this time. RESULTS: During the control period, there were 48 head trauma admissions who met the inclusion criteria. In 22 patients (45.8 %), PTP was initiated at an average of 4.9 ± 5.4 days after admission. During the protocol period, there were 87 head trauma admissions taken from 1,143 total NSICU stays who met criteria. In 63 patients (72.4 %), the care team in the NSICU successfully initiated PTP, at an average of 3.4 ± 2.8 days after admission. All 87 trauma patients were analyzed, and the rate of clinically significant deep venous thrombosis (DVT) was 6.9 % (6 of 87). Three protocol patients (3.45 %) went to the operating room for surgery after the initiation of PTP; none of these patients had a measurable change in hemorrhage size on head CT. The change in percentage of patients receiving PTP was significantly increased by the protocol (p < 0.0001); while the average days to first PTP dose trended down with institution of the protocol, this change was not statistically significant. CONCLUSION: A PTP protocol in the NSICU is useful in controlling the number of complications from DVT and pulmonary embolism while avoiding additional IH. This protocol, based on a published body of literature, allowed for VTE rates similar to published rates, while having no PTP-related hemorrhage expansion. The protocol significantly changed physician behavior, increasing the percentage of patients receiving PTP during their hospitalization; whether long-term patient outcomes are affected is a potential goal for future study.

Posture-independent piston valve: a novel valve mechanism that actuates based on intracranial pressure alone.

OBJECT: Shunt valves are intended to maintain physiological intracranial pressure (ICP). A variety of mechanisms have been designed to accomplish this goal but have had limited success. Siphoning, in particular, has been a problem not effectively solved by proposed or manufactured valves. Poor control of ICP results in headache, neurological disturbances, decreased cognition, shunt malfunction, slit ventricles, subdural hematomas, decreased cranial volume, and maldevelopment. The authors of this study describe a prototype valve that was machined and tested ex vivo and that actuates based on ICP alone regardless of the presence of a siphon. Their object was to determine if a novel shunt mechanism that actuates perpendicular to the flow of fluid would eliminate the effect of siphoning in a valve for the treatment of hydrocephalus. METHODS: A posture-independent piston valve (PIPV) was anchored to a graduated reservoir. Opening pressure was measured by noting the fluid level in the reservoir when the piston moved. Measurements were made using a 90-cm and a 120-cm water-filled siphon tube (1.3-mm standard distal catheter) to simulate an upright posture. A recumbent posture was simulated by the absence of a siphon. RESULTS: Opening pressure of the valve did not change regardless of the presence or absence of a water-filled siphon. CONCLUSIONS: The PIPV was triggered only by the pressure head at the inlet and did not actuate in the presence of a siphon, demonstrating proof of principle of the perpendicular actuating mechanism. The PIPV is a purely mechanical device that has practical application in the treatment of hydrocephalus.

Cerebellar hemorrhage as a first presentation of acquired Hemophilia A.

BACKGROUND: Acquired hemophilia A (AHA) is an uncommon coagulation disorder caused by the development of autoantibodies against coagulation factor VIII (FVIII). While intracranial hemorrhage is a known complication of AHA, intracranial hemorrhage as the presenting manifestation of AHA has only been described in three previous case reports. METHOD: We report a case of an 86-year-old woman with no previously reported history of coagulopathy presenting with an acute intraparenchymal cerebellar hemorrhage and laboratory studies demonstrating an isolated prolonged activated partial thromboplastin time (aPTT). We discuss an approach to the prolonged aPTT, and review the literature concerning the diagnosis and treatment of AHA. RESULTS: Occipital decompressive craniectomy with evacuation of the hemorrhage was performed. Eight hours following the procedure, the patient's status acutely declined with demonstration of a reoccurrence of the cerebellar hemorrhage and new right frontal lobe hemorrhage. After discussion with the patient's family, life-sustaining support measures were withdrawn. Postmortem analysis revealed a low FVIII activity level and the presence of FVIII inhibitor. CONCLUSION: The presentation of intracranial hemorrhage with an isolated prolonged aPTT is concerning for an acquired hemophilia with FVIII deficiency. Other causes of isolated prolonged aPTT such as a lupus anticoagulant must also be considered. Preoperative identification and work-up of the coagulation abnormality is essential to guide initial treatment.

Microwave beamforming for non-invasive patient-specific hyperthermia treatment of pediatric brain cancer.

We present a numerical study of an array-based microwave beamforming approach for non-invasive hyperthermia treatment of pediatric brain tumors. The transmit beamformer is designed to achieve localized heating-that is, to achieve constructive interference and selective absorption of the transmitted electromagnetic waves at the desired focus location in the brain while achieving destructive interference elsewhere. The design process takes into account patient-specific and target-specific propagation characteristics at 1 GHz. We evaluate the effectiveness of the beamforming approach using finite-difference time-domain simulations of two MRI-derived child head models from the Virtual Family (IT'IS Foundation). Microwave power deposition and the resulting steady-state thermal distribution are calculated for each of several randomly chosen focus locations. We also explore the robustness of the design to mismatch between the assumed and actual dielectric properties of the patient. Lastly, we demonstrate the ability of the beamformer to suppress hot spots caused by pockets of cerebrospinal fluid (CSF) in the brain. Our results show that microwave beamforming has the potential to create localized heating zones in the head models for focus locations that are not surrounded by large amounts of CSF. These promising results suggest that the technique warrants further investigation and development.

Time-multiplexed beamforming for noninvasive microwave hyperthermia treatment.

A noninvasive microwave beamforming strategy is proposed for selective localized heating of biological tissue. The proposed technique is based on time multiplexing of multiple beamformers. We investigate the effectiveness of the time-multiplexed beamforming in the context of brain hyperthermia treatment by using a high-fidelity numerical head phantom of an adult female from the Virtual Family (IT'IS Foundation) as our testbed. An operating frequency of 1 GHz is considered to balance the improved treatment resolution afforded by higher frequencies against the increased penetration through the brain afforded by lower frequencies. The exact head geometry and dielectric properties of biological tissues in the head are assumed to be available for the creation of patient-specific propagation models used in beamformer design. Electromagnetic and thermal simulations based on the finite-difference time-domain method are used to evaluate the hyperthermia performance of time-multiplexed beamforming and conventional beamforming strategies. The proposed time-multiplexing technique is shown to reduce the unintended heating of healthy tissue without affecting the treatment temperature or volume. The efficacy of the method is demonstrated for target locations in three different regions of the brain. This approach has the potential to improve microwave-induced localized heating for cancer treatment via hyperthermia or heat-activated chemotherapeutic drug release.

Stability of Sodium Nitroprusside and Sodium Thiosulfate 1:10 Intravenous Admixture.

PURPOSE: Thiosulfate has been shown to reduce the risk of cyanide toxicity during nitroprusside administration. Admixtures containing both agents may provide a safe and effective alternative to more expensive agents used to reduce blood pressure in the critically ill patient. This study determined the physical and chemical stability of a 1:10 nitroprusside:thiosulfate admixture, stored up to 48 hours. The economic consequences of a shift toward using thiosulfate and nitroprusside, and away from higher cost alternatives, are considered. METHODS: Seven samples of 50 mg nitroprusside and 500 mg thiosulfate were prepared and stored away from light, at room temperature, and in a refrigerator prepared in D5W and NS. Each sample was analyzed via a novel high-performance liquid chromatographic (HPLC) method at time 0, 8, 24, and 48 hours. The method was tested and passed specifications for linearity, reproducibility, and accuracy. A visual inspection by 9 licensed pharmacists was used to demonstrate physical stability. A cost evaluation comparing nitroprusside and thiosulfate to alternative agents was completed. RESULTS: The concentration of both nitroprusside and thiosulfate remain greater than 95% of the initial concentration through 48 hours. Physical compatibility was confirmed in all samples tested through 72 hours. CONCLUSION: The combination of nitroprusside and thiosulfate is chemically and physically stable as a single compounded dose for up to 48 hours when stored at room temperature and protected from light. The admixture represents an inexpensive option to other higher cost alternatives such as nicardipine or clevidipine.