Computational model based on optical coherence tomography (OCT) skin scanning to identify and quantify acute radiation dermatitis (ARD): a prospective diagnostic study

BACKGROUND

acute radiation dermatitis (ARD) is the most widely reported radiotherapy-induced adverse event. Currently, there is no objective or reliable method to measure ARD.

OBJECTIVE

our main objective was to identify and quantify the effects of radiotherapy with a computational model using optical coherence tomography (OCT) skin scanning. Secondary objectives included determining the ARD impact of different radiotherapeutic schemes and adjuvant topical therapies.

METHODS

we conducted a prospective, single-center case series study in a tertiary referral center of patients with breast cancer who were eligible for whole breast radiotherapy (WBRT).

RESULTS

a total of 39 women were included and distributed according to the radiotherapeutic schemes (15, 20, and 25 fractions). A computational model was designed to quantitatively analyze OCT findings. After radiotherapy, OCT scanning was more sensitive revealing vascularization changes in 84.6% of the patients (vs 69.2% of the patients with ARD by clinical examination). OCT quantified an increased vascularization at the end of WBRT (P < .05) and a decrease after 3 months (P = .032). Erythematous skin changes by OCT were more pronounced in the 25-fraction regime.

CONCLUSION

an OCT computational model allowed for the identification and quantification of vascularization changes on irradiated skin, even in the absence of clinical ARD. This may allow the design of standardized protocols for ARD beyond the skin color of the patients involved.

Performance of the Aktiia optical blood pressure measurement device in the elderly: a comparison with double blinded auscultation in different body positions

BACKGROUND

Accurate blood pressure (BP) measurement is essential for the correct diagnosis and management of hypertension (HTN) especially in the elderly population. As with of all BP devices, the accuracy of cuffless devices must be verified. This study (NCT04027777) aimed to evaluate the performance of a wrist cuffless optical BP device in an elderly population cohort in different body positions with auscultation as the reference measurement.

DESIGN AND METHODS

Patients aged 65-85 years with different BP categories but without diabetes were recruited. After an initial calibration based on auscultatory measurements, BP estimation from the Aktiia Bracelet (Aktiia SA, Switzerland) were compared to reference double-blinded auscultatory measurements in sitting, standing and lying positions on four separate visits distributed over one month. In the absence of a universal standard for cuffless BP device at the time of the study, modified ISO81060-2 criteria were used for performance analysis.

RESULTS

Thirty-five participants were included in the analysis fulfilling the inclusion requirements of ISO 81060-2. A total of 469 paired measurements were obtained with overall 83% acceptance rate. Differences (mean ± SD)   between Aktiia Bracelet and auscultation for systolic BP were -0.26 ± 9.96 mmHg for all body positions aggregated (sitting 1.23 ± 7.88 mmHg, standing -1.81 ± 11.11 mmHg, lying -1.8 ± 9.96 mmHg). Similarly, differences for diastolic BP were -0.75 ± 7.0 mmHg (0.2 ± 5.55 mmHg, -5.35 ± 7.75 mmHg and -0.94 ± 7.47 mmHg, respectively). Standard deviation of the averaged differences per subject for systolic/diastolic BP was 3.8/2.5 mmHg in sitting and 4.4/3.7 mmHg for all body positions aggregated.

CONCLUSIONS

Overall, this study demonstrates a similar performance of the Aktiia Bracelet compared to auscultation in an elderly population in body positions representative of daily activities. The use of more comfortable, non-invasive, and non-occlusive BP monitors during long periods may facilitate e-health and may contribute to better management of HTN, including diagnosis and treatment of HTN, in the elderly.

Aktiia cuffless blood pressure monitor yields equivalent daytime blood pressure measurements compared to a 24-h ambulatory blood pressure monitor: Preliminary results from a prospective single-center study

In this preliminary study, we compared daytime blood pressure (BP) measurements performed by a commercially available cuffless-and continual-BP monitor (Aktiia monitor, Neuchâtel, Switzerland) and a traditional ambulatory BP monitor (ABPM; Dyasis 3, Novacor, Paris, France) from 52 patients enrolled in a 12-week cardiac rehabilitation (CR) program (Neuchâtel, Switzerland). Daytime (9am-9pm) systolic (SBP) and diastolic (DBP) BP from 7-day averaged data from Aktiia monitor were compared to 1-day averaged BP data from ABPM. No significant differences were found between the Aktiia monitor and the ABPM for SBP (μ ± σ [95% confidence interval]: 1.6 ± 10.5 [-1.5, 4.6] mmHg, P = 0.306; correlation [R2]: 0.70; ± 10/ ± 15 mmHg agreements: 60%, 84%). Marginally non-significant bias was found for DBP (-2.2 ± 8.0 [-4.5, 0.1] mmHg, P = 0.058; R2: 0.66; ±10/±15 mmHg agreements: 78%, 96%). These intermediate results show that daytime BP measurements using the Aktiia monitor generate data comparable to that of an ABPM monitor.

Validation of the Aktiia blood pressure cuff for clinical use according to the ANSI/AAMI/ISO 81060-2:2013 protocol

OBJECTIVE

Assess the accuracy and precision of the Aktiia initialization oscillometric upper-arm cuff device (Aktiia SA, Neuchâtel, Switzerland) for home blood pressure (BP) monitoring in the general population according to the American National Standards Institute / Association for the Advancement of Medical Instrumentation/International Organization for Standardization (ANSI/AAMI/ISO) 81060-2:2013 standard.

METHODS

Three trained observers validated BP measurements performed using the Aktiia cuff versus BP measurements performed using a standard mercury sphygmomanometer. Two ISO 81060-2 criteria were used to validate the Aktiia cuff. Criterion 1 evaluated, for both SBP and DBP, whether the mean error between BP readings performed by the Aktiia cuff and auscultation was ≤±5 mmHg, and whether the SD of the error was ≤8 mmHg. Criterion 2 assessed whether, for the SBP and DBP of each individual subject, the SD of the averaged paired determinations per subject of the Aktiia cuff and of the auscultation met the criteria listed in the table of Averaged Subject Data Acceptance.

RESULTS

Mean differences between the Aktiia cuff and the standard mercury sphygmomanometer (criterion 1) were 1.3 ± 7.11 mmHg for SBP and -0.2 ± 5.46 mmHg for DBP. The SD of the averaged paired differences per subject (criterion 2) was 6.55 mmHg for SBP and 5.15 mmHg for DBP.

CONCLUSION

Aktiia initialization cuff complies with the requirements of the ANSI/AAMI/ISO guidelines and can be safely recommended for BP measurements in the adult population.

Abstract P304: Persistent Use Of Aktiia 24/7 Blood Pressure Monitor Is Associated With Lower Blood Pressure In Hypertensive Patients

Introduction: Cuffless blood pressure (BP) monitors are a promising innovation for hypertension diagnosis and monitoring. Aktiia (Aktiia 24/7 BP Monitor, Aktiia, Switzerland) is a CE-marked, commercially available BP monitor that passively and continually collects BP waveforms via optical sensors at the wrist. After initial cuff calibration, the app displays BP estimates on a smartphone. No data exist on the impact of persistently showing a person their BP data with this device.

Hypothesis: If people with hypertension persistently use Aktiia and are exposed to their BP data, there will be a change in behavior resulting in measurably lower BP.

Methods: We analyzed the systolic BP (SBP) trends of 838 real-world users (Age 57±11, 14% female) who consistently used Aktiia for 6 months (375±287 app interactions, 3646±1417 cuffless readings per user, and 9±7 cuff readings per user). Users were grouped by the mean monthly SBP (<140 and >140 mmHg) calculated over 6 months. Then, cuff SBP averages were calculated monthly and compared to the SBP average of the first month. A t-test analysis was used to detect the difference in SBP between the first and successive months.

Results: Hypertensive users (SBP > 140 mmHg) saw a reduction in SBP of -3.2 mmHg (CI: -0.70, -5.59, p<0.02), beginning at 3 months and sustained through 6 months. For users with SBP < 140 mm Hg, the mean SBP remained unchanged (Fig. 1).

Conclusion: Persistent BP monitoring with Aktiia’s cuffless device is associated with a significant, sustained reduction in SBP for hypertensive patients at 6 months. Possible explanations include the Hawthorne effect or intensified treatment.

Guidance for the Interpretation of Continual Cuffless Blood Pressure Data for the Diagnosis and Management of Hypertension

Hypertension remains the leading risk factor for death worldwide. Despite its prevalence, success of blood pressure (BP) management efforts remains elusive, and part of the difficulty lies in the tool still used to diagnose, measure, and treat hypertension: the sphygmomanometer introduced by Samuel Siegfried Karl von Basch in 1867. In recent years, there has been an explosion of devices attempting to provide estimates of BP without a cuff, overcoming many limitations of cuff-based BP monitors. Unfortunately, the differences in underlying technologies between traditional BP cuffs and newer cuffless devices, as well as hesitancy of changing a well-implemented standard, still generate understandable skepticism about and reluctance to adopt cuffless BP monitors in clinical practice. This guidance document aims to navigate the scientific and medical communities through the types of cuffless devices and present examples of robust BP data collection which are better representations of a person's true BP. It highlights the differences between data collected by cuffless and traditional cuff-based devices and provides an initial framework of interpretation of the new cuffless datasets using, as an example, a CE-marked continual cuffless BP device (Aktiia BP Monitor, Aktiia, Switzerland). Demonstration of novel BP metrics, which have the potential to change the paradigm of hypertension diagnosis and treatment, are now possible for the first time with cuffless BP monitors that provide continual readings over long periods. Widespread adoption of continual cuffless BP monitors in healthcare will require a collaborative and thoughtful process, acknowledging that the transition from a legacy to a novel medical technology will be slow. Finally, this guidance concludes with a call to action to international scientific and expert associations to include cuffless BP monitors in original scientific research and in future versions of guidelines and standards.

Three-dimensional imaging through patterned type-1 microscopy

We report a scanning non-confocal fluorescence microscopy scheme that provides images with optical sectioning and with a lateral resolution that surpasses by a factor of two the diffraction resolution limit. This technique is based on the type-1 microscopy concept combined with patterned illumination. The method does not require the application of phase-shifting or post-processing algorithms and provides artifact-free superresolved 3D images. We have validated the theory by means of experimental data.

Validation of the optical Aktiia bracelet in different body positions for the persistent monitoring of blood pressure

The diagnosis of hypertension and the adjustment of antihypertensive drugs are evolving from isolated measurements performed at the physician offices to the full phenotyping of patients in real-life conditions. Indeed, the strongest predictor of cardiovascular risk comes from night measurements. The aim of this study was to demonstrate that a wearable device (the Aktiia Bracelet) can accurately estimate BP in the most common body positions of daily life and thus become a candidate solution for the BP phenotyping of patients. We recruited 91 patients with BP ranging from low to hypertensive levels and compared BP values from the Aktiia Bracelet against auscultatory reference values for 4 weeks according to an extended ISO 81060-2 protocol. After initializing on day one, the observed means and standard deviations of differences for systolic BP were of 0.46 ± 7.75 mmHg in the sitting position, − 2.44 ± 10.15 mmHg in the lying, − 3.02 ± 6.10 mmHg in the sitting with the device on the lap, and − 0.62 ± 12.51 mmHg in the standing position. Differences for diastolic BP readings were respectively of 0.39 ± 6.86 mmHg, − 1.93 ± 7.65 mmHg, − 4.22 ± 6.56 mmHg and − 4.85 ± 9.11 mmHg. This study demonstrates that a wearable device can accurately estimate BP in the most common body positions compared to auscultation, although precision varies across positions. While wearable persistent BP monitors have the potential to facilitate the identification of individual BP phenotypes at scale, their prognostic value for cardiovascular events and its association with target organ damage will need cross-sectional and longitudinal studies. Deploying this technology at a community level may be also useful to drive public health interventions against the epidemy of hypertension.

Blood pressure from the optical Aktiia Bracelet: a 1-month validation study using an extended ISO81060-2 protocol adapted for a cuffless wrist device

OBJECTIVE

The objective of this study (NCT04027777) was to assess the accuracy and precision of the Aktiia Bracelet, a CE-marked noninvasive optical blood pressure (BP) monitor worn at the wrist, over a period of 1 month.

METHODS

In this study, participants aged between 21 and 65 years were recruited. The clinical investigation extended the ISO81060-2:2013 standard to the specificities of cuffless devices. Each BP assessment consisted of the simultaneous recording of optical signals with Aktiia Bracelet and double-blinded auscultation by two trained observers in the standard sitting position. The algorithms of Aktiia Bracelet further processed the recorded optical signals to perform a signal quality check and to calculate uncalibrated estimates of systolic BP (SBP) and diastolic BP (DBP). These estimates were transformed into mmHg using a subject-dependent calibration parameter, which was calculated using the first two available reference measurements per subject.

RESULTS

Eighty-six participants were included in the analysis. The mean and SD of the differences between Aktiia Bracelet estimates and the reference (ISO81060-2 criterion 1) were 0.46 ± 7.75 mmHg for SBP and 0.39 ± 6.86 mmHg for DBP. The SD of the averaged paired difference per subject (ISO81060-2 criterion 2) were 3.9 mmHg for SBP and 3.6 mmHg for DBP.

CONCLUSION

After initialization and during 1 month, the overall accuracy of Aktiia Bracelet satisfied validation criteria 1 and 2 of ISO81060-2 in the sitting position. The Aktiia Bracelet can be recommended for BP measurement in the adult population.

Cuffless systolic and diastolic blood pressure estimation at the wrist via an optical device: comparison to intra-arterial measurements

 

The diagnosis and management of hypertension usually requires the estimation of blood pressure (BP) by means of an inflatable cuff. This procedure generates discomfort and limits patient compliance. Cuffless devices capture BP readings without performing any arterial occlusion. We believe that comfortable and cuffless BP monitoring devices can significantly aid in the fight against hypertension and support the expansion of ambulatory and remote patient monitoring programs, provided that these devices provide reliable BP readings.

The purpose of this study was to compare the systolic (S) and diastolic (D) blood pressure (BP) estimations from a new optical device at the wrist (figure) against invasive measurements performed on patients scheduled for radial arterial catheterization. The first results from this study were recently published and demonstrated good agreement for the overall study population. Here we report expanded statistical analyses for different population subgroups such as gender, age, body mass index (BMI) and skin color.

The study protocol consisted of the simultaneous recording of reflective photo-plethysmographic signals (PPG) from the optical device, and BP values recorded by a contralateral radial arterial catheter. The PPG signals were processed to generate estimates of SBP and DBP. Agreement of paired BP estimations was further calculated in terms of standard deviation (SD) of differences. The mean of differences were systematically zero because BP estimations from the optical device were calibrated for each patient.

The table shows that, for the overall population, both SBP and DBP differences SDs were smaller than 8 mmHg (as already published). Furthermore, across different population groups, both genders, all BMIs and all skin colors also resulted in SDs smaller than 8 mmHg. Only patients whose age was above 65 years were associated with a higher SD.

For the overall population and most subgroups the new optical technique appears to be capable of replacing more traditional methods of BP estimation. Only the SBP differences for the subgroup of older patients were larger. Additional studies are needed to confirm and expand these very encouraging results.

Table 1. SD of measured BP differences Population N SD of SBP differences SD of DBP differences (mmHg) (mmHg) All 16 7.1 2.9 Gender Male 10 6.4 2.8 Female 6 8.0 3.1 Age (years) &lt;65 7 4.0 2.3 &gt;65 9 *9.3 3.4 BMI (kg/m2) &lt;26 10 7.9 2.9 &gt;26 6 5.7 2.8 Skin Color (Fitzpatrick) 2 13 7.7 3.0 3 3 4.5 2.6 *Only subgroup with a SD larger than 8mmHg.

Figure 1. The investigational device

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): Aktiia SA

Are cuffless devices challenged enough? Design of a validation protocol for ambulatory blood pressure monitors at the wrist: the case of the Aktiia Bracelet

The US and European guidelines for the diagnosis and management of hypertension recommend the introduction of systematic home and night Blood Pressure (BP) monitoring. Fully-automated wearable devices can address the needs of patients and clinicians by improving comfort while achieving measurement accuracy. Often located at the wrist and based on indirect BP measurements, these devices must address the challenges of ambulatory scenarios. New validation strategies are needed, but little guidance has been published so far.In this work, we propose an experimental protocol for the validation of cuffless wrist BP monitors that addresses ambulatory environment challenges in a controlled experimental setting. The protocol assesses the robustness of the measurement for different body postures, the ability of the device to track BP changes, and its ability to deal with hydrostatic pressure changes induced by different arm heights.Performance testing using Aktiia Bracelet is provided as an illustration. The results of this pilot study indicate that the Aktiia Bracelet can generate accurate BP estimates for sitting and lying positions and is not affected by hydrostatic pressure perturbations.Clinical Relevance- Automated cuffless BP monitoring is opening a new chapter in the way patients are being diagnosed and managed. This paper provides a guidance on how to assess the clinical utility of such devices when used in different body positions.

Abstract P192: Is Auscultation Adequate To Estimate Blood Pressure Responses Related To Body Position Changes?

Double-blinded auscultation is the current reference to validate new devices in the sitting position. There are few data to tell whether it should be used for device validation in other body positions, as the Korotkoff sounds can be affected by changes in vascular tone. In this study, we recorded the BP response to orthostatic posture change (standing to supine) in 75 subjects, aged between 21 and 65 years old. Systolic (SBP) and diastolic (DBP) were measured on the left upper arm by auscultation by two independent blinded observers before and 150s after posture change. In case the observers did not agree, i.e. readings differed more than 4 mmHg, the measurement was repeated. Beat-to-beat BP values were measured on the ipsilateral middle finger with Nexfin (BMEYE, The Netherlands). Because Nexfin measurements were not available during upper-arm cuff inflation, the mean of the values in a 30s window prior to auscultation onset was used for the analysis. The distribution of the BP responses to posture change was characterized in terms of median, 10 th and 90 th percentiles (see Table). The response was considered consistent if these percentiles were on the same side of zero. Neither auscultation nor Nexfin detected any consistent posture-related changes in SBP when going from standing to supine. Nexfin detected a consistent decrease in DBP. Auscultation detected no consistent posture-related change. Compared to volume-clamp, auscultation was not able to detect any consistent changes in DBP during orthostatic challenge. Our study suggests that the use of Korotkoff sounds to estimate BP in body positions other than sitting may not be appropriate.

AB1051 KIKUCHI FUJIMOTO DISEASE, IS IT SLE?

Background:

Kikuchi-Fujimoto disease (KFD) is a rare entity characterized by adenopathies and fever. It raises a broad differential diagnosis that includes lymphoproliferative disorders, infections and systemic autoimmune diseases, and diagnostic confirmation is always by histology, which shows histiocytic necrotizing lymphadenitis. Although its course is generally benign and self-limited, it can be associated both at the time of diagnosis and during follow-up with systemic autoimmune diseases, the most frequent of which is systemic lupus erythematosus (SLE).

Objectives:

To describre the clinical and analytical characteristics of patients diagnosed with KFD and the development of systemic autoimmune disease.

Methods:

Patients diagnosed with KFD during the 1990s and 2020s are collected in a regional hospital (Granollers General Hospital). The clinic is documented at the diagnosis of EKF, the appearance of systemic autoimmune disease during follow-up and its clinical and analytical characteristics.

Results:

A total of 7 patients with EKF were diagnosed. All of them women with a mean age at diagnosis of 30 years. Diagnosis was made in all cases with compatible clinical symptoms, fever and lymphadenopathy, and lymph node biopsy confirming histiocytic necrotizing lymphadenitis. At the time of diagnosis, a patient was also diagnosed with SLE. During the follow-up, 4 of the 6 remaining patients developed clinical manifestations compatible with SLE (3 of them with systemic manifestations and a case of subacute cutaneous lupus. The mean time of onset of SLE was 34 months (between 6 months and 5 years). All of them received treatment with hydroxychloroquine, with good response to treatment.

The clinical and analytical characteristics are presented in Table 1 below.

Conclusion:

In our center, 5 of the 7 patients (71%) diagnosed with EKF developed manifestations compatible with SLE. The importance of the diagnosis of EKF lies precisely in the possible association with systemic autoimmune disease, the most common being SLE, so it is recommended that patients be monitored to identify those who develop associated autoimmune disease.

Disclosure of Interests:

None declared

Towards an unsupervised device for the diagnosis of childhood pneumonia in low resource settings: automatic segmentation of respiratory sounds

Pneumonia remains the worldwide leading cause of children mortality under the age of five, with every year 1.4 million deaths. Unfortunately, in low resource settings, very limited diagnostic support aids are provided to point-of-care practitioners. Current UNICEF/WHO case management algorithm relies on the use of a chronometer to manually count breath rates on pediatric patients: there is thus a major need for more sophisticated tools to diagnose pneumonia that increase sensitivity and specificity of breath-rate-based algorithms. These tools should be low cost, and adapted to practitioners with limited training. In this work, a novel concept of unsupervised tool for the diagnosis of childhood pneumonia is presented. The concept relies on the automated analysis of respiratory sounds as recorded by a point-of-care electronic stethoscope. By identifying the presence of auscultation sounds at different chest locations, this diagnostic tool is intended to estimate a pneumonia likelihood score. After presenting the overall architecture of an algorithm to estimate pneumonia scores, the importance of a robust unsupervised method to identify inspiratory and expiratory phases of a respiratory cycle is highlighted. Based on data from an on-going study involving pediatric pneumonia patients, a first algorithm to segment respiratory sounds is suggested. The unsupervised algorithm relies on a Mel-frequency filter bank, a two-step Gaussian Mixture Model (GMM) description of data, and a final Hidden Markov Model (HMM) interpretation of inspiratory-expiratory sequences. Finally, illustrative results on first recruited patients are provided. The presented algorithm opens the doors to a new family of unsupervised respiratory sound analyzers that could improve future versions of case management algorithms for the diagnosis of pneumonia in low-resources settings.

Basophil Histamine Release Induced by Amoxicilloyl-poly-L-lysine Compared With Amoxicillin in Patients With IgE-Mediated Allergic Reactions to Amoxicillin

BACKGROUND

Amoxicillin (AX) is the ß-lactam most often involved in IgE-mediated reactions. Diagnosis is based mainly on skin testing, although sensitivity is not optimal. We produced a new AX derivative, amoxicilloyl-poly-L-lysine (APL), and analyzed its recognition of IgE using the passive histamine release test (pHRT).

METHODS

The study population comprised patients (n=19) with confirmed AX allergy and specific IgE to AX and controls (n=10) with good tolerance to AX. pHRT was performed using "IgE-stripped" blood from a single donor that was sensitized in vitro by patient sera and incubated with AX or APL. Histamine release was determined and expressed as nanograms of histamine released per milliliter of blood.

RESULTS

The clinical symptoms were anaphylaxis (n=9), urticaria (n=7), erythema (n=2), and nondefined immediate reactions (n=1). The median (IQR) time interval between reaction and study was 90 (60-240) days and between drug intake and development of symptoms 24 (10-60) minutes. The median sIgE level was 3.37 (0.95-5.89) kUA/L. The sensitivity of pHRT to APL was 79% and the specificity 100%, which were higher than data obtained with pHRT to AX (63% sensitivity and 90% specificity). There was a positive correlation between maximal histamine release levels obtained with AX and APL (r=0.63).

CONCLUSIONS

In patients with immediate hypersensitivity reactions to AX, APL showed higher sensitivity and specificity than the culprit drug, AX, when tested in vitro by pHRT. This indicates that APL can improve the in vitro diagnostic accuracy of allergic reactions to AX. Further assessment of skin testing is necessary.

A Versatile Noise Performance Metric for Electrical Impedance Tomography Algorithms

Electrical impedance tomography (EIT) is an emerging technology for real-time monitoring of patients under mechanical ventilation. EIT has the potential to offer continuous medical monitoring while being noninvasive, radiation free, and low cost. Due to their ill-posedness, image reconstruction typically uses regularization, which implies a hyperparameter controlling the tradeoff between noise rejection and resolution or other accuracies. In order to compare reconstruction algorithms, it is common to choose hyperparameter values such that the reconstructed images have equal noise performance (NP), i.e., the amount of measurement noise reflected in the images. For EIT many methods have been suggested, but none work well when the data originate from different measurement setups, such as for different electrode positions or measurement patterns. To address this issue, we propose a new NP metric based on the average signal-to-noise ratio in the image domain. The approach is validated for EIT using simulation experiments on a human thorax model and measurements on a resistor phantom. Results show that the approach is robust to the measurement configuration (i.e., number and position of electrodes, skip pattern) and the reconstruction algorithm used. We propose this novel approach as a way to select optimized measurement configurations and algorithms.

Non-invasive monitoring of pulmonary artery pressure at the bedside

Current solutions for the monitoring of pulmonary artery pressure (PAP) in patients suffering from pulmonary hypertension are limited to invasive means. Non-invasive alternatives, such as Doppler echocardiography, are incompatible with continuous monitoring due to their dependency on qualified personnel to perform the measurements. In the present study, a novel non-invasive and unsupervised approach based on the use of electrical impedance tomography (EIT) is presented. The approach was evaluated in three healthy subjects undergoing hypoxia-induced variations in PAP. A timing parameter - physiologically linked to the PAP via the so-called pulse wave velocity principle - was automatically extracted from the EIT data. Reference systolic PAP estimates were obtained by echocardiography. Strong correlation scores (r e [0.844, 0.990]) were found between the EIT-derived parameter and the reference PAP, thereby suggesting the validity of the proposed approach. If confirmed in larger datasets, these findings could open the way for a new branch of fully non-invasive hemodynamic monitors for patients with pulmonary hypertension.

Nutritional Status Deteriorates Postoperatively Despite Preoperative Nutritional Support

Background/Aims: The aim of the current study was to assess the postoperative evolution of nutritional status and to relate it with postoperative outcomes. Methods: Demographic, surgical and nutritional parameters were assessed 10 days preoperatively (d-10) and 30 days postoperatively (d30) in 146 patients. Risk factors responsible for perioperative (>5% between d-10 and d30) weight loss were identified. Overall, severe (Clavien 3-5) and infectious complications were compared in patients with and without perioperative weight loss (>5%). Results: Nutritional status worsened beyond the postoperative period as reflected by decreasing weight (67 ± 13 kg at d-10 vs. 63 ± 13 kg at d30, p < 0.001), body mass index (23.4 ± 4 vs. 22.2 ± 4 kg/m2, p < 0.001) and mid upper-arm muscle circumference (MAMC, 241 ± 32 vs. 232 ± 30 mm, p < 0.001). Fifty-two patients (46%) lost >5% of their body weight between d-10 and d30. Patients who presented overall (63 vs. 36%, p = 0.004) and major (27 vs. 10%, p = 0.016) postoperative complications were at significantly higher risk to deteriorate postoperative nutritional status. Multivariate analysis identified low preoperative lean body mass (OR 3.2; 95% CI 1.2-8.9, p = 0.023) and low preoperative MAMC (OR 2.5; 95% CI 0.9-6.8, p = 0.066) as independent risk factors for perioperative weight loss. Conclusions: These data suggest continuing nutritional follow-up after the index hospitalization.

Physical activity profiling: Activity-specific step counting and energy expenditure models using 3D wrist acceleration

In this paper, we present the evaluation of a new physical activity profiling system embedded in a wrist-located device. We propose a step counting and an energy expenditure (EE) method, and evaluate their accuracy against gold standard references. To this end, we used an actimetry sensor on the waist and an indirect calorimetry monitoring device on a population of 13 subjects to obtain step count and metabolic equivalent task (kcal/kg/h) referenced values. The subjects followed a protocol that spanned a given set of activities (lying, standing, walking, running) at a wide range of intensities. The performance of the EE model was characterized by a root-mean-square error (RMSE) of 1.22±0.34kcal/min, and step-count model at regular walking/running speeds by 0.71±0.06step/10sec.

Validation of a wrist monitor for accurate estimation of RR intervals during sleep

While the incidence of sleep disorders is continuously increasing in western societies, there is a clear demand for technologies to asses sleep-related parameters in ambulatory scenarios. The present study introduces a novel concept of accurate sensor to measure RR intervals via the analysis of photo-plethysmographic signals recorded at the wrist. In a cohort of 26 subjects undergoing full night polysomnography, the wrist device provided RR interval estimates in agreement with RR intervals as measured from standard electrocardiographic time series. The study showed an overall agreement between both approaches of 0.05 ± 18 ms. The novel wrist sensor opens the door towards a new generation of comfortable and easy-to-use sleep monitors.

Continuous monitoring of coordinated cardiovascular responses

The continuous separate monitoring of cardiac and vascular functions provide important insights on cardiovascular regulation. In the last years several attempts have failed at demonstrating the feasibility of using Pulse Wave Velocity as a surrogate indicator of arterial blood pressure. Upon the hypothesis that the cause of PWV unreliability is vasomotor activity, in this paper we develop an extended model of lumped arterial tree that copes with changes in vessels diameter. The benefit of this approach is twofold: on the one hand one might correct the effects of vasomotor activity on the estimation of arterial blood pressure on the basis of PWV, and on the other hand one obtains continuous non-invasive estimations of Cardiac Output and Total Peripheral Resistance.

[Fever, pleural effusion and osteolytic lesion in a patient with HIV infection]

We present the case of a 28 year old patient who came for consultation on a fever of up to 40.8 degrees C, pleuritic pain on the right side and the appearance of a painful mass in the lower left extremity of four days evolution. Computerised axial tomography (CAT) showed the existence of a condensation in the middle lobe of the right lung with associated pleural effusion and bilateral miliary pattern. The echographic study of the lower left extremity showed a mass of soft parts with a cystic aspect with destruction of the cortical of the fibula and osseous destruction. Magnetic resonance confirmed the presence of osteomyelitis in the left fibula and of an abscess; Mycobacterium tuberculosis was also isolated in three samples of sputum that led to a diagnosis of disseminated tuberculosis with miliary lung affectation, peroneous osteomyelitis and tuberculous abscess of the soft parts. Anti-tuberculosis treatment was started (riphampicine, isoniacide and pirazinamide) followed, two weeks later, with antiretroviral treatment (AZT, 3TC and NVP). The patient developed a clinical picture of generalised cutaneous eruption that disappeared following the replacement of the riphampicine by etambutol. Due to the persistence of the mass of soft parts following five weeks of anti-tuberculosis treatment, we proceeded to surgical draining of the abscess. The subsequent evolution was favourable, with the patient remaining asymptomatic one month after hospital discharge.

Combination of multiple light paths in pulse oximetry: the finger ring example

When pulse oximetry is required at other body locations than the finger tip new strategies for optical setups and signal handling are required. In this paper we present a combination of short and long light paths that succeeded in resolving the problems associated to the development of a finger ring SpO2 sensor.

[Tuberculosis in patients with HIV infection]

Tuberculosis is a clear example of infection that requires cellular immunity for its control. The spread throughout the world of the Human Immunodeficiency Virus (HIV) resulted in its interaction with tuberculosis altering the descending curve of the latter disease in some developed countries, and brought an aggravation of the problem in other countries with few economic and health resources and where tuberculosis was endemic. HIV increases the risk of reactivation of latent tuberculosis infection and accelerates progression after infection or reinfection; on the other hand, TB aggravates the prognosis of patients infected with HIV. This article sets out the differential aspects in the clinical manifestations of TB amongst populations with and without HIV infection; we also comment on some special characteristics in the treatment of tuberculosis in HIV patients. With the exception of primary cutaneous infections produced by accidental inoculation and infantile lymphadenitis, the majority of the cases of disease due to non-tuberculosis mycobacteria (NTM) affect patients with certain predisposing factors. In the case of patients with AIDS, the deep immunological disorder provoked by HIV brings a particular susceptibility to suffering invasive disease due to certain NTM, principally M. avium complex and M. kansasii.