Technical note: development of a tidal volume surrogate that replaces spirometry for physiological breathing monitoring in 4D CT.
Ontology highlight
ABSTRACT: Spirometry exhibits baseline drift and frequent measurement errors so it cannot be used by itself to provide tidal volume-based image sorting or breathing motion modeling. Other breathing surrogates, in this study an abdominal bellows system, are drift free but do not measure tidal volume. Simultaneously using spirometry and the bellows system allows the user to convert the recorded bellows signal to tidal volume but still relies on spirometry measurements. The authors therefore propose to use CT-based air content, rather than a spirometer, to convert the bellows signal to tidal volume.41 4D CT data sets are acquired, while the breathing cycle is simultaneously measured using spirometry and an abdominal pressure bellows system. The assumptions underlying the conversion of the bellows measurement to tidal volume by CT-based air content are analyzed. This comprises of detailed correlation studies of the spirometry-measured tidal volume, the bellows signal, and CT-based air content.For 15/41 patients, the spirometry signals are not consistently acquired during the 4D CT session, so correlating spirometry to bellows measurements and CT-based air content leads to erroneous conversion coefficients. After introducing a minimum correlation threshold to remove these data, good correlations are obtained between the remaining breathing signals. The ratio of CT-based air content to tidal volume is measured to be 1.11 +/- 0.08; the expected value is 1.11 because room air is 11% more dense than air in the lungs.The observed problems of spirometry recording illustrate the challenges encountered when using spirometers as breathing surrogate for 4D CT acquisition. The high correlation between spirometry and bellows breathing signals and the verified factor of 1.11 between CT-based air content and tidal volume mean that the bellows measurement (or other equivalent surrogates) can be reliably converted to tidal volume using the CT-based air content, avoiding the need for a spirometer.
Project description:Respiratory monitoring systems are required to supply CT scanners with information on the patient's breathing during the acquisition of a respiration-correlated computer tomography (RCCT), also referred to as 4D CT. The information a respiratory monitoring system has to provide to the CT scanner depends on the specific scanner. The purpose of this study is to compare two different respiratory monitoring systems (Anzai Respiratory Gating System; C-RAD Sentinel) with respect to their applicability in combination with an Aquilion Large Bore CT scanner from Toshiba. The scanner used in our clinic does not make use of the full time dependent breathing signal, but only single trigger pulses indicating the beginning of a new breathing cycle. Hence the attached respiratory monitoring system is expected to deliver accurate online trigger pulse for each breathing cycle. The accuracy of the trigger pulses sent to the CT scanner has to be ensured by the selected respiratory monitoring system. Since a trigger pulse (output signal) of a respiratory monitoring system is a function of the measured breathing signal (input signal), the typical clinical range of the input signal is estimated for both examined respiratory monitoring systems. Both systems are analyzed based on the following parameters: time resolution, signal amplitude, noise, signal-to-noise ratio (SNR), signal linearity, trigger compatibility, and clinical examples. The Anzai system shows a better SNR (≥ 28 dB) than the Sentinel system (≥ 14.6 dB). In terms of compatibility with the cycle-based image sorting algorithm of the Toshiba CT scanner, the Anzai system benefits from the possibility to generate cycle-based triggers, whereas the Sentinel system is only able to generate amplitude-based triggers. In clinical practice, the combination of a Toshiba CT scanner and the Anzai system will provide better results due to the compatibility of the image sorting and trigger release methods.
Project description:People with transtibial limb loss experience daily changes in volume of their residual limb that affect the fit of their prosthetic socket. A portable instrument was developed to monitor fluid volume changes outside of the laboratory setting. The bioimpedance system applied 26 current bursts per second at frequencies between 3 kHz and 1 MHz, and sensed voltage at up to six channels. Among six voltage-controlled current source circuits and five receive-channel amplifier topologies considered, a differential Howland current pump and a single receive-channel instrumentation amplifier proved the best combination of low noise and low power consumption. Mean RMS errors were 0.07% for extracellular fluid resistance, 2.23% for intracellular fluid resistance, and 1.15% for membrane capacitance.
Project description:The internet of healthcare things aims at connecting biosensors, clinical information systems and electronic health dossiers. The resulting data expands traditionally available diagnostics with digital biomarkers. In this technical note, we report the implementation and pilot operation of a device- and analytics-agnostic automated monitoring platform for in-house patients at hospitals. Any available sensor, as well as any analytics tool can be integrated if the application programming interface is made available. The platform consists of a network of Bluetooth gateways communicating via the hospital's secure Wi-Fi network, a server application (Device Hub) and associated databases. Already existing access points or low-cost hardware can be used to run the gateway software. The platform can be extended to a remote patient monitoring solution to close the gap between in-house treatments and follow-up patient monitoring.
Project description:PurposeThe purposes of the study are to describe current practice of ventilation in a modern air medical system and to measure the association of ventilation strategy with subsequent ventilator care and acute respiratory distress syndrome (ARDS).Materials and methodsRetrospective observational cohort study of intubated adult patients (n = 235) transported by a university-affiliated air medical transport service to a 711-bed tertiary academic center between July 2011 and May 2013. Low tidal volume ventilation was defined as tidal volumes less than or equal to 8 mL/kg predicted body weight. Multivariable regression was used to measure the association between prehospital tidal volume, hospital ventilation strategy, and ARDS.ResultsMost patients (57%) were ventilated solely with bag valve ventilation during transport. Mean tidal volume of mechanically ventilated patients was 8.6 mL/kg predicted body weight (SD, 0.2 mL/kg). Low tidal volume ventilation was used in 13% of patients. Patients receiving low tidal volume ventilation during air medical transport were more likely to receive low tidal volume ventilation in the emergency department (P < .001) and intensive care unit (P = .015). Acute respiratory distress syndrome was not associated with prehospital tidal volume (P = .840).ConclusionsLow tidal volume ventilation was rare during air medical transport. Air transport ventilation strategy influenced subsequent ventilation but was not associated with ARDS.
Project description:PurposeRadiation dose delivered to targets located near the upper abdomen or thorax are significantly affected by respiratory motion, necessitating large margins, limiting dose escalation. Surrogate motion management devices, such as the Real-time Position Management (RPM™) system (Varian Medical Systems, Palo Alto, CA), are commonly used to improve normal tissue sparing. Alternative to current solutions, we have developed and evaluated the feasibility of a real-time position management system that leverages the motion data from the onboard hardware of Apple iOS devices to provide patients with visual coaching with the potential to improve the reproducibility of breathing as well as improve patient compliance and reduce treatment delivery time.Methods and materialsThe iOS application, coined the Instant Respiratory Feedback (IRF) system, was developed in Swift (Apple Inc., Cupertino, CA) using the Core-Motion library and implemented on an Apple iPhone® devices. Operation requires an iPhone®, a three-dimensional printed arm, and a radiolucent projector screen system for feedback. Direct comparison between IRF, which leverages sensor fusion data from the iPhone®, and RPM™, an optical-based system, was performed on multiple respiratory motion phantoms and volunteers. The IRF system and RPM™ camera tracking marker were placed on the same location allowing for simultaneous data acquisition. The IRF surrogate measurement of displacement was compared to the signal trace acquired using RPM™ with univariate linear regressions and Bland-Altman analysis.ResultsPeriodic motion shows excellent agreement between both systems, and subject motion shows good agreement during regular and irregular breathing motion. Comparison of IRF and RPM™ show very similar signal traces that were significantly related across all phantoms, including those motion with different amplitude and frequency, and subjects' waveforms (all r > 0.9, P < 0.0001). We demonstrate the feasibility of performing four-dimensional cone beam computed tomography using IRF which provided similar image quality as RPM™ when reconstructing dynamic motion phantom images.ConclusionsFeasibility of an iOS application to provide real-time respiratory motion is demonstrated. This system generated comparable signal traces to a commercially available system and offers an alternative method to monitor respiratory motion.
Project description:BackgroundCare of the child after hip-spica application is the most challenging issue faced by parents. Reduced mobility and recumbency can cause respiratory problems, skin irritation and discomfort for the child. Parents need to lift the child in a spica to make him upright and to mobilize. To improve the comfort of the family in post spica care, we have designed a 'Hip Spica Stroller' which is low profile, comfortable, easy to construct and relatively inexpensive. This manuscript discusses our early experience with this hip-spica stroller use.MethodsA sturdy, relatively lightweight and portable stroller was designed in collaboration with local mechanical engineering team. The stroller allowed safe upright placement of the child with spica and their easy mobility. From the second post-operative day, children were mobilised in the stroller. We looked for development of any complications related to the stroller such as spica breakage, skin irritation or excoriation development. Parents were also inquired about their feedback and satisfaction with the device upon spica removal.ResultsWe used the spica stroller in nine patients after Developmental Dysplasia Hip (DDH) treatment and in eight patients post shaft femur fracture treatment. None of the patients experienced any stroller-related complications. All the patients maintained the joint reduction and the fractured bone fragment alignment. High satisfaction rates were reported by parents.ConclusionHip Spica Stroller is an innovative and easy-to-make device which would enhance the post spica care. It can aid alleviating the fear of parents for their child's hip-spica treatment.Supplementary informationThe online version contains supplementary material available at 10.1007/s43465-021-00568-2.
Project description:BackgroundMethods to guide fluid therapy in spontaneously breathing patients are scarce. No studies have reported the accuracy of end-tidal CO2 (ET-CO2) to predict volume responsiveness in these patients. We sought to evaluate the ET-CO2 gradient (ΔET-CO2) after a passive leg rise (PLR) maneuver to predict volume responsiveness in spontaneously breathing healthy adults.MethodsWe conducted a prospective study in healthy adult human volunteers. A PLR maneuver was performed and cardiac output (CO) was measured by transthoracic echocardiography. ET-CO2 was measured with non-invasive capnographs. Volume responsiveness was defined as an increase in cardiac output (CO) > 12% at 90 s after PLR.ResultsOf the 50 volunteers, 32% were classified as volume responders. In this group, the left ventricle outflow tract velocity time integral (VTILVOT) increased from 17.9 ± 3.0 to 20.4 ± 3.4 (p = 0.0004), CO increased from 4.4 ± 1.5 to 5.5 ± 1.6 (p = 0.0), and ET-CO2 rose from 32 ± 4.84 to 33 ± 5.07 (p = 0.135). Within the entire population, PLR-induced percentage ∆CO was not correlated with percentage ∆ET-CO2 (R2 = 0.13; p = 0.36). The area under the receiver operating curve for the ability of ET-CO2 to discriminate responders from non-responders was of 0.67 ± 0.09 (95% CI 0.498-0.853). A ΔET-CO2 ≥ 2 mmHg had a sensitivity of 50%, specificity of 97.06%, positive likelihood ratio of 17.00, negative likelihood ratio of 0.51, positive predictive value of 88.9%, and negative predictive value of 80.5% for the prediction of fluid responsiveness.ConclusionsΔET-CO2 after a PLR has limited utility to discriminate responders from non-responders among healthy spontaneously breathing adults.
Project description:Ultrasound (US) imaging is a well-recognized technique for the study of static tissues but its suitability for studying tissue dynamics depends upon accurate frame time information, which may not always be available to users. Here we present methods to quantify the inter-frame interval (IFI) variability, and evaluate different procedures for collecting temporal information from two US-imaging devices. The devices tested exhibited variable IFIs that could only be confirmed by direct measures of timing signals, available by means of electrical signals (triggers) and/or temporal information contained in the software used for the US data collection. Interpolating frame-by-frame measures of dynamic changes within image sequences using individual IFI values provided improved synchronization between measures of skeletal muscle movement and activation; validating US as a valuable technique for the study of musculoskeletal tissue dynamics, when correctly implemented.
Project description:PurposePercutaneous endoscopic lumbar discectomy (PELD) is a minimally invasive disc surgery that can be performed under local anesthesia and requires only an eight-mm skin incision. For the patients with lumbar foraminal stenosis, the migrated disc is difficult to remove with a simple transforaminal approach. In such cases, the foraminoplasty techniques can be used. However, obtaining efficient foramen enlargement while minimizing radiation exposure and protecting the nerves can be challenging.MethodsIn this study, we propose a new technique called the Kiss-Hug maneuver. Under endoscopic viewing, we used the bevel tip of a working cannula as a bone reamer to enlarge the foramen. This allowed us to efficiently enlarge the lumbar foramen endoscopically without the redundancy and complications associated with reamers or trephines.ResultsDetails of the four steps of the Kiss-Hug maneuver are reported along with adverse events. The advantages of this new technique include minimizing radiation exposure to both the surgeon and the patient and decreasing the overall operation time.ConclusionThe endoscopic Kiss-Hug maneuver is a useful and reliable foraminoplasty technique that can enhance the efficiency of foraminoplasty while ensuring patient safety and reducing radiation exposure.
Project description:Articular cartilage lesions are identified with increasing frequency. Several cartilage repair techniques are available to treat symptomatic cartilage defects. The ultimate goal of any cartilage repair procedure is the prevention of premature osteoarthritis. Autologous chondrocyte implantation provides the best tissue quality. However, 2 operations and a resource-intense culturing process with high regulatory demands are disadvantages of this cartilage repair procedure. Furthermore, cellular dedifferentiation and senescence display further cell culture-associated drawbacks that hamper the procedure. Minced cartilage implantation is a relatively simple and cost-effective one-step procedure with promising biologic potential and satisfying clinical results. We present an arthroscopic surgical technique where the surgeon can apply autologous chondrocytes in a one-step procedure to treat articular cartilage defects at the knee joint.