Intelligent checklists improve checklist compliance in the intensive care unit: a prospective before-and-after mixed-method study.

BACKGROUND: We examined whether a context and process-sensitive 'intelligent' checklist increases compliance with best practice compared with a paper checklist during intensive care ward rounds. METHODS: We conducted a single-centre prospective before-and-after mixed-method trial in a 35 bed medical and surgical ICU. Daily ICU ward rounds were observed during two periods of 8 weeks. We compared paper checklists (control) with a dynamic (digital) clinical checklist (DCC, intervention). The primary outcome was compliance with best clinical practice, measured as the percentages of checked items and unchecked critical items. Secondary outcomes included ICU stay and the usability of digital checklists. Data are presented as median (interquartile range). RESULTS: Clinical characteristics and severity of critical illness were similar during both control and intervention periods of study. A total of 36 clinicians visited 197 patients during 352 ward rounds using the paper checklist, compared with 211 patients during 366 ward rounds using the DCC. Per ICU round, a median of 100% of items (94.4-100.0) were completed by DCC, compared with 75.1% (66.7-86.4) by paper checklist (P=0.03). No critical items remained unchecked by the DCC, compared with 15.4% (8.3-27.3) by the paper checklist (P=0.01). The DCC was associated with reduced ICU stay (1 day [1-3]), compared with the paper checklist (2 days [1-4]; P=0.05). Usability of the DCC was judged by clinicians to require further improvement. CONCLUSIONS: A digital checklist improved compliance with best clinical practice, compared with a paper checklist, during ward rounds on a mixed ICU. CLINICAL TRIAL REGISTRATION: NCT03599856.

A U - Net Deep Learning Model for Infant Heart Rate Estimation from Ballistography.

Ballistography(BSG) is a non-intrusive and low- cost alternative to electrocardiography (ECG) for heart rate (HR) monitoring in infants. Due to the inter-patient variance and susceptibility to noise, heartbeat detection in the BSG waveform remains a challenge. The aim of this study was to estimate HR from a bed-based pressure mat BSG signal using a deep learning approach. We trained a U-Net deep neural network through supervised learning by deriving ground truth as the location of the heartbeats from simultaneously recorded ECG signals after peak matching. For improved generalization, we modified an existing U - Net to include an IC-layer. A predictive performance of 80% was achieved using the U-Net without the IC-layer. The inclusion of the IC-layer, while improving the generalization ability of the model to detect heartbeats, did not improve the HR estimation performance.

Exploration of using a pressure sensitive mat for respiration rate and heart rate estimation.

Measuring the respiration and heart rate unobtrusively in home settings is an important goal for health monitoring. In this work, use of a pressure sensitive mat was explored. Two methods using body morphology information, based on shoulder blades and weighted centroid, were developed for respiration rate (RR) calculation. Heart rate (HR) was calculated by combining the frequency information from different body regions. Experimental data were collected from 15 participants in a supine position via a pressure sensitive mat placed under the upper torso. RR and HR estimations derived from accelerometer sensors attached to participants' bodies were used as references to evaluate the accuracy of the proposed methods. All three methods achieved a reasonable estimation compared to the reference. The root mean squared error of the proposed RR estimation methods were 1.32 and 0.87 breath/minute respectively, and the root mean squared error of the HR estimation method was 5.55 bpm.

Investigation of a Ballistocardiogram-Based Technique for Unobtrusive Monitoring of Fluid Accumulation in the Body.

We introduce a novel monitoring solution for fluid accumulation in the human body (e.g. internal bleeding), based on observation of a selected energy-describing feature of the Ballistocardiogram (BCG) signal. It is hypothesized that, because of additional damping generated by the fluid, BCG signal energy decreases as compared to its baseline value. Data were collected from 15 human volunteers via accelerometers attached to the participants' body, and an electromechanical-film (EMFi) sensor-equipped bed. Fluid accumulation along the gastrointestinal (GI) tract was induced by means of water intake by the participants, and the BCG signal was recorded before and after intake. Based on performance evaluation, we selected a suitable energy feature and sensing channel amongst the ones investigated. The chosen feature showed a significant decrease in signal energy from baseline to after-intake condition (p-value<0.001), and identified the presence of fluid accumulation with high sensitivity (90% in bed-based, and 100% in standing-position monitoring).

Evaluating the Performance of Cardiac Pulse Duplicators Through the Concept of Fidelity.

INTRODUCTION: The advanced design techniques used in modern prosthetic heart valve (PHV) development require accurate replication of the entire cardiac cycle. While cardiac pulse duplicator (CPD) design has a direct impact on the PHV test data generated, no clear guidelines exist to evaluate the CPD's performance. In response to this, we present a method to quantitatively assess CPD performance. MATERIALS AND METHODS: A method to establish the fidelity of CPDs was formulated based on the pressure/time relationship and the error related to this relationship's target. This method was applied to assess the performance of a custom-made CPD. The performance evaluation included the assessment of the motion control system and overall repeatability of pressure measurements using a St Jude Epic 21 mm aortic valve. RESULTS: The CPD's motion control system had an average root mean square error (RMSE) beat-to-beat tracking accuracy of 0.046 ± 0.008 mm. Assessment of the pressure measurements yielded a repeatability of < 2.4 ± 0.9 mmHg RMSE beat-to-beat differential pressure. The combination of pressure and its location within a heartbeat (fidelity) was within 5.0% of the individual targets for at least 95% of heartbeats. CONCLUSION: Fidelity can be used to objectively quantify the performance of various aspects of CPDs and to identify the cause of unexpected PHV or CPD behaviour. It also enables comparisons to be made among various CPDs in terms of overall performance. This approach may enable standardization of the assessment of CPD performance in the future.

Development of a wearable support system to aid the visually impaired in independent mobilization and navigation.

Visually impaired individuals have great difficulty in navigating unfamiliar environments. Conventional methods of obstacle detection are not always sufficient, thus a need exists for a low-cost device which could aid the visually impaired in navigating indoor environments. The aim of this study is to develop a wearable prototype support system which aids the visually impaired in independent navigation and mobilization. It utilizes ultrasonic sensors to detect obstacles and transmits feedback to the user through an array of vibration motors. The prototype device was evaluated by detecting the sensor signatures of various common static household obstacles. Trends were identified in these signatures which can be used to give feedback to the user of the type of obstacle encountered. The results show the basic feasibility of the device in static indoor obstacle detection and identification for the visually impaired. However, further refinement is needed to extend the system's functionality by detecting dynamic obstacles.

Implementation of a manually operated blood pressure monitor based on energy harvesting for use in resource-constrained settings.

Health workers who screen for hypertension in rural and resource-constrained settings face many challenges including limited training, difficulties in correctly performing blood pressure (BP) measurements, and electrical grid unreliability. The aim of this study is to present the implementation of a manually operated BP monitor which assists health workers in overcoming some of these challenges by harvesting energy during manual cuff inflation and then discharging it in a controlled manner to power BP data acquisition, storage and wireless transmission. A prototype device was fabricated using a rotary alternator, flywheel and capacitor which harvests and stores energy when the bulb is squeezed during cuff inflation. Testing of the prototype revealed that an average of 1.55 J of energy can be scavenged during 30 s of cuff inflation. This is sufficient for BP data acquisition, storage and wireless transmission to a near-by smartphone even when accounting for losses.

Development of a gesture and voice controlled system for burn injury prevention in individuals with disabilities.

Burn injury is a major public health issue in developing countries, with most injuries being largely associated with the use of kitchen stoves. This study details the development of a cost-effective gesture and voice recognition controlled (GVC) system to be used by individuals with disabilities to reduce the likelihood of burn injury and improve their quality of life. The device replaces conventional dial controls with voice and hand gesture recognition sensors and software which are designed to be easily implemented into a household kitchen. Preliminary evaluation of the GVC system's performance in gesture and voice recognition, gas leak detection and ignition control tests were conducted using a Bunsen burner as a stove top surrogate. The voice and gesture recognition tests yielded sensitivities of 88% and 100%, respectively. These results suggest that the GVC system may be a promising solution for burn injury prevention pending further work to improve its reliability and robustness.

Investigation of the feasibility of non-invasive optical sensors for the quantitative assessment of dehydration.

This study explores the feasibility of prospectively assessing infant dehydration using four non-invasive, optical sensors based on the quantitative and objective measurement of various clinical markers of dehydration. The sensors were investigated to objectively and unobtrusively assess the hydration state of an infant based on the quantification of capillary refill time (CRT), skin recoil time (SRT), skin temperature profile (STP) and skin tissue hydration by means of infrared spectrometry (ISP). To evaluate the performance of the sensors a clinical study was conducted on a cohort of 10 infants (aged 6-36 months) with acute gastroenteritis. High sensitivity and specificity were exhibited by the sensors, in particular the STP and SRT sensors, when combined into a fusion regression model (sensitivity: 0.90, specificity: 0.78). The SRT and STP sensors and the fusion model all outperformed the commonly used "gold standard" clinical dehydration scales including the Gorelick scale (sensitivity: 0.56, specificity: 0.56), CDS scale (sensitivity: 1.0, specificity: 0.2) and WHO scale (sensitivity: 0.13, specificity: 0.79). These results suggest that objective and quantitative assessment of infant dehydration may be possible using the sensors investigated. However, further evaluation of the sensors on a larger sample population is needed before deploying them in a clinical setting.

Development of a diagnostic feedback device to assess neonatal cardiopulmonary resuscitation chest compression performance.

Neonatal cardiopulmonary resuscitation (NCPR) is an important intervention to save the lives of newborns who suffer from cardiac and respiratory arrest. Despite its importance there is a dearth of NCPR research and no commercially available feedback device suitable for use during NCPR. The aim of this study is to develop a diagnostic feedback device in the form of a patch placed on the infant's chest. The diagnostic feedback patch measures both the compression depth and force during NCPR, while giving audio-visual feedback according to current NCPR guidelines. The patch was systematically evaluated by conducting a series of hardware validation tests to assess the depth, force and feedback performance. The average errors in the depth and force were found to be 10.8% and 12.4%, respectively, with maximal errors below 20.7% and 24.1%. These results along with positive outcome of the feedback test suggest that the device is reliable on a hardware level and is suitable for further evaluation in a clinical setting.

Towards an algorithm for automatic accelerometer-based pulse presence detection during cardiopulmonary resuscitation.

Manual palpation is still the gold standard for assessment of pulse presence during cardiopulmonary resuscitation (CPR) for professional rescuers. However, this method is unreliable, time-consuming and subjective. Therefore, reliable, quick and objectified assessment of pulse presence in cardiac arrest situations to assist professional rescuers is still an unmet need. Accelerometers may present a promising sensor modality as pulse palpation technology for which pulse detection at the carotid artery has been demonstrated to be feasible. This study extends previous work by presenting an algorithm for automatic, accelerometer-based pulse presence detection at the carotid site during CPR. We show that accelerometers might be helpful in automated detection of pulse presence during CPR.

Development of diagnostic sensors for infant dehydration assessment using optical methods.

Dehydration resulting from acute diarrhea is one of the leading causes of infant mortality in the developing world. Safe assessment of an infant's hydration level is essential to determine appropriate clinical intervention strategies. However, clinical hydration scales, which are the current gold standard for non-invasive hydration assessment, are often unreliable in lower resource settings. This study presents the development and testing of non-invasive, optical sensors for the objective assessment of dehydration based on the quantitative measurement of skin recoil time, capillary refill time and skin temperature. The results obtained have demonstrated the basic feasibility of using optical sensors for the objective assessment of dehydration. However, several challenges must be overcome before these sensors can be applied in a clinical setting.

Development of a diagnostic dehydration screening sensor based on infrared spectrometry.

The clinical assessment of dehydration is highly subjective and requires experienced and highly trained clinical personnel. At present no objective method for quantitatively determining an individual's dehydration status exists. The aim of this study is to address this deficiency by presenting the development and testing of a novel diagnostic tool for dehydration detection based on infrared spectrometry. Laboratory testing and two clinical studies were conducted to evaluate the efficacy of the device in both adults and infants. The results were promising for the infant study with a clear trend exhibited. However, a number of challenges must be overcome before this sensor can be applied in a clinical setting.

Pulse detection with a single accelerometer placed at the carotid artery: Performance in a real-life diagnostic test during acute hypotension.

Pulse detection via palpation is a basic and essential procedure in daily medical practice. We have been investigating the performance of a single accelerometer placed above the carotid artery, which is one of the recommended locations for manual palpation. A low-cost sensor attached by an adhesive measures accelerations due to carotid dilatations and whole body vibrations. A real-time demonstrator has been developed to classify 10 second- windows in "Pulse", "Motion" and "No Pulse" and to infer pulse rate. Data were obtained during a scheduled head-up tilt table test (HUTT). Our results show for a subgroup of 10 patients with acute hypotension a wide spread of "good" signal coverage ranging from as low as 37% up to 100%. Key factors compromising the performance in HUTT are motion artifacts, arrhythmias, sensor placement and sensor-skin coupling. In conclusion, pulse detection with a single accelerometer is sufficiently accurate, if good signal coverage can be achieved.

Evaluation of the use of frequency response in the diagnosis of pleural effusion on a phantom model of the human lungs.

Pleural effusion is one of the most widespread respiratory diseases in the world. Current diagnostic techniques include a combination of medical history and x-ray or CT scan imaging of the chest. However, these techniques are expensive and impractical in resource limited settings. We propose a new method based on sound transmission into the respiratory system through the chest wall. To evaluate this technique, a sine sweep signal with a frequency range between 100 Hz and 1000 Hz was transmitted into a phantom model of the human lungs capable of simulating healthy and effused conditions. The frequency response of the model under both conditions was computed and compared to evaluate the diagnostic performance of the new method. The results indicate that there is a significant difference between the frequency response of healthy and effused lungs, which suggests that the new technique may be suitable for the clinical diagnosis of pleural effusion.

Feasibility of pulse presence and pulse strength assessment during head-up tilt table testing using an accelerometer located at the carotid artery.

Neurally mediated syncope (NMS) is a disorder of the autonomic regulation of postural tone, which is characterized by hypotension and/or bradycardia, resulting in cerebral hypo-perfusion and finally in a sudden loss of consciousness. Prediction of an impending NMS requires detection of pulse presence to derive heart rate (HR) as well as to assess the pulse strength (PS) related to systolic blood pressure (SBP) preferably from a single body location only. This paper analyses the basic feasibility of using a single accelerometer positioned above the common carotid artery to assess pulse strength and pulse rate towards NMS prediction. A physical model has been investigated to gain insights into expected signal morphologies and potential feature candidates vs. hemodynamic parameters such as SBP, pulse pressure (PP) and PR relevant for NMS detection. Model results are compared with first measurements obtained in a head-up tilt table test (HUTT) from a patient during impending syncope. We show that an accelerometer positioned at the carotid artery is a potential approach offering a valuable tool in syncope management.

Development of a smart backboard system for real-time feedback during CPR chest compression on a soft back support surface.

The quality of cardiopulmonary resuscitation (CPR) is often inconsistent and frequently fails to meet recommended guidelines. One promising approach to address this problem is for clinicians to use an active feedback device during CPR. However, one major deficiency of existing feedback systems is that they fail to account for the displacement of the back support surface during chest compression (CC), which can be important when CPR is performed on a soft surface. In this study we present the development of a real-time CPR feedback system based on an algorithm which uses force and dual-accelerometer measurements to provide accurate estimation of the CC depth on a soft surface, without assuming full chest decompression. Based on adult CPR manikin tests it was found that the accuracy of the estimated CC depth for a dual accelerometer feedback system is significantly better (7.3% vs. 24.4%) than for a single accelerometer system on soft back support surfaces, in the absence or presence of a backboard. In conclusion, the algorithm used was found to be suitable for a real-time, dual accelerometer CPR feedback application since it yielded reasonable accuracy in terms of CC depth estimation, even when used on a soft back support surface.

Development of a diagnostic glove for unobtrusive measurement of chest compression force and depth during neonatal CPR.

Optimizing chest compression (CC) performance during neonatal cardiopulmonary resuscitation (CPR) is critical to improving survival outcomes since current clinical protocols often achieve only a fraction of the native cardiovascular perfusion. This study presents the development of a diagnostic tool to unobtrusively measure the CC depth and force during neonatal CPR using sensors mounted on a glove platform. The performance of the glove was evaluated by infant manikin tests using the two-thumb (TT) and two-finger (TF) methods of CC during simulated, unventilated neonatal CPR. The TT method yielded maximum CC depths and forces of as much as 25.7 ± 3.2 mm and 35.9 ± 2.2 N while the TF method produced CC depths and forces of as much as 21.6 ± 2.2 mm and 23.7 ± 2.9 N. These results are consistent with clinical findings which suggest that TT compression is more effective than TF compression since it produces greater CC depths and forces.

Optimal chest compression in cardiopulmonary resuscitation depends upon thoracic and back support stiffness.

A biomechanical analysis of the constant peak displacement and constant peak force methods of cardiopulmonary resuscitation (CPR) has revealed that optimal CC performance strongly depends on back support stiffness, CC rate, and the thoracic stiffness of the patient being resuscitated. Clinically the results presented in this study suggest that the stiffness of the back support surfaces found in many hospitals may be sub-optimal and that a backboard or a concrete floor can be used to enhance CC effectiveness. In addition, the choice of optimal CC rate and maximum sternal force applied by clinicians during peak force CPR is ought to be based on a general assessment of the patient's thoracic stiffness, taking into account the patient's age, gender, and physical condition; which is consistent with current clinical practice. In addition, it is important for clinicians to note that very high peak sternal forces, exceeding the limit above which severe chest wall trauma and abdominal injury occurs, may be required for optimal CC during peak force CPR on patients with very stiff chests. In these cases an alternative CPR technique may be more appropriate.

In vitro characterization of an aortic bioprosthetic valve using Doppler echocardiography and qualitative flow visualization.

A 19 mm diameter prototype bioprosthetic valve mounted in a cardiac pulse duplicator was characterized using Doppler echocardiography and qualitative flow visualization at a heart rate of 72 bpm. Analysis of the flow visualization images revealed that the prototype and control valve leaflets open symmetrically but close asymmetrically. The asymmetry in the closing of the valves is likely due to the large pressure gradients across the valves and may have implications for the long term mechanical failure of the valves. The relatively high peak systolic velocity of 309.9 cm/s, which was measured in the prototype 19 mm valve, can be attributed to the small valve diameter and the high cardiac output used in the current study.