Portable high-end instrument for in-vivo infrared spectroscopy using spread spectrum modulation

Near infrared spectroscopy (NIRS) can be employed to monitor noninvasively and continuously local changes in hemodynamics and oxygenation of human tissues. In particular, the technique can be particularly useful for muscular functional monitoring during unattended physical activity. A portable NIRS research-grade acquisition system, dedicated to low-noise measurements during muscular exercise, is presented. A spread-spectrum multiplexing scheme significantly enhances system performance. The resulting instrument is compact, lightweight and efficient. Preliminary tests on oxygen consumption during exercise and venous occlusion show excellent detectivity and time response

Perioperative comparison of the agreement between a portable fingertip pulse oximeter vs. a conventional bedside pulse oximeter in adult patients (COMFORT trial)

Background: Low-cost, portable fingertip pulse oximeters are widely available to health professionals and the public. They are often not tested to ISO standards, or only undergo accuracy studies in healthy volunteers under ideal laboratory conditions. This study aims to pragmatically evaluate the agreement between one such device and a conventional bedside pulse oximeter in a clinical setting, in patients with varied comorbidities and skin pigmentations. Methods: A single-centre equipment comparison study was conducted. Simultaneous measurements were obtained in 220 patients with both a Contec CMS50D Fingertip Pulse Oximeter and a Nihon Kohden Life Scope MU-631 RK conventional bedside monitor. Peripheral oxygen saturations (SpO₂) and pulse rates were documented, and patient skin tone was recorded using the Fitzpatrick scale. Data was assessed using a Bland-Altman analysis with bias, precision and limits of agreement (LOA) calculated with 95% confidence intervals. A priori acceptability for LOA was determined to be 3%, in keeping with international standards. Results: Mean difference (therefore bias) between the conventional and fingertip oximeters for all data was -0,55% (95% CI -0,73 to -0,36%). Upper and lower limits of agreement (95% CI) were 2,16 (1,84 to 2,47) and -3,25 (-3,56 to -2,94) %. Regression analysis demonstrated worsening agreement with decreasing SpO₂. When samples were separated into “normal” (SpO₂ ≥ 93%) and “hypoxaemic” (SpO₂ < 93%) groups, the normal range displayed acceptable agreement between the two oximeters (bias -0,20 with LOA 2,20 to -2,27%), while the hypoxaemic group fell outside the study’s a priori limits. Heart rate measurements had mean difference (LOA) of -0,43 (-5,61 to 4,76) beats per minute. The study was not powered to detect difference among the skin tones, but demonstrated no trend for this parameter to alter the SpO₂ measurements. Conclusions: During normoxia, portable fingertip pulse oximeters are reliable indicators of SpO₂ and pulse rates in patients with various comorbidities in a pragmatic clinical context. However, they display worsening agreement with conventional pulse oximeters during hypoxaemia. Skin tones do not appear to adversely affect measurements

Vital Sensory Kit For Use With Telemedicine In Developing Countries

In many developing countries, a large percentage of the population lacks access to adequate healthcare. This is especially true in India where close to 70% of the population lives in rural areas and has little to no access to hospitals or clinics. People living in rural India often times cannot afford to pay to see a doctor should they need to make the journey to a hospital. Telemedicine, a breakthrough in the past couple decades, has broken down the barrier between the patient and the physician. It has slowly been implemented in India to make doctors more available to patients through the use of video conferences and other forms of communication. A compact and affordable kit has been developed that will be used to take a patient’s blood pressure, heart rate, blood glucose concentration and oxygen saturation. Our most novel contribution is the non-invasive glucose sensor that will use a near-infrared LED and photodiode in the patient’s earlobe. Currently millions of diabetics do this by pricking their finger. By wirelessly sending data results from the vital sign kit, the first essential part of a treatment can be carried out via wireless communication, saving the doctor and patient time and money

Compression under pressure: physiological and methodological factors influencing the effect of compression garments on running economy

Evidence for the effects of compression garments on sports performance and physiological responses to dynamic exercise remains equivocal. Contradictory findings within the sporting literature are confounded by methodological heterogeneity in terms of; intensity and modality of exercise, type of garment worn, and the interface pressure produced by the garment. The interface pressure applied by compression clothing is an important measure in evaluating the bio-physical impact of compression. Interface pressure values obtained in vivo with two portable pressure devices (PicoPress and Kikuhime) were compared against a reference standard (HOSY). The PicoPress satisfied the a priori thresholds for acceptable validity at the posterior and lateral orientation with calf stockings and tights, confirming its future use to assess interface pressure. A small, likely beneficial improvement in running economy was observed with correctly fitted (95%:5%:0%; η2 = 0.55) but not oversized compression tights, indicating that a certain level of interface pressure is required. Compression tights improved running economy only at higher relative exercise intensities (77.7 - 91.5% V̇O2max). The absence of any improvement at lower intensities (67.1 - 77.6 % V̇O2max) suggest that changes in running economy from compression are dependent on relative exercise intensity when V̇O2max (%) is used as an anchor of exercise intensity. Comparing measures from two portable, wireless near-infrared spectroscopy (NIRS) devices (PortaMon and MOXY) we found that the low-cost and light-weight MOXY device gave tissue oxygen saturation values at rest and during exercise that were physiologically credible and suitable for future research. Compression tights did affect ground contact time but not tissue oxygen saturation, cardiovascular or other kinematic parameters during running at intensities equivalent to long-distance race speed. Compression tights can produce small improvements in running economy, but effects are restricted to higher intensity exercise and appear dependent on garment interface pressure. It remains unlikely that this small positive effect on running economy, in very specific conditions, is enough to result in a meaningful impact on running performance

A Novel, Contactless, Portable “Spot-Check” Device Accurately Measures Respiratory Rate

Respiratory rate (RR) is an important vital sign used in the assessment of acutely ill patients. It is also used as to predict serious deterioration in a patient's clinical condition. Convenient electronic devices exist for measurement of pulse, blood pressure, oxygen saturation and temperature. Although devices which measure RR exist, none has entered everyday clinical practice. We developed a contactless portable respiratory rate monitor (CPRM) and evaluated the agreement in respiratory rate measurements between existing methods and our new device. The CPRM uses thermal anemometry to measure breath signals during inspiration and expiration. RR data were collected from 52 healthy adult volunteers using respiratory inductance plethysmography (RIP) bands (established contact method), visual counting of chest movements (established non-contact method) and the CPRM (new method), simultaneously. Two differently shaped funnel attachments were evaluated for each volunteer. Data showed good agreement between measurements from the CPRM and the gold standard RIP, with intra-class correlation coefficient (ICC): 0.836, mean difference 0.46 and 95% limits of agreement of -5.90 to 6.83. When separate air inlet funnels of the CPRM were analysed, stronger agreement was seen with an elliptical air inlet; ICC 0.908, mean difference 0.37 with 95% limits of agreement -4.35 to 5.08. A contactless device for accurately and quickly measuring respiratory rate will be an important triage tool in the clinical assessment of patients. More testing is needed to explore the reasons for outlying measurements and to evaluate in the clinical setting

A prospective pilot clinical trial evaluating the utility of a dynamic near-infrared imaging device for characterizing suspicious breast lesions

Introduction: Characterizing and differentiating between malignant tumors, benign tumors, and normal breast tissue is increasingly important in the patient presenting with breast problems. Near-infrared diffuse optical imaging and spectroscopy is capable of measuring multiple physiologic parameters of biological tissue systems and may have clinical applications for assessing the development and progression of neoplastic processes, including breast cancer. The currently available application of near-infrared imaging technology for the breast, however, is compromised by low spatial resolution, tissue heterogeneity, and interpatient variation. Materials and methods: We tested a dynamic near-infrared imaging schema for the characterization of suspicious breast lesions identified on diagnostic clinical ultrasound. A portable handheld near-infrared tissue imaging device (P-Scan; ViOptix Inc., Fremont, CA, USA) was utilized. An external mechanical compression force was applied to breast tissue. The tissue oxygen saturation and hemoglobin concentration were recorded simultaneously by the handheld near-infrared imaging device. Twelve categories of dynamic tissue parameters were derived based on real-time measurements of the tissue hemoglobin concentration and the oxygen saturation. Results: Fifty suspicious breast lesions were evaluated in 48 patients. Statistical analyses were carried out on 36 out of 50 datasets that satisfied our inclusion criteria. Suspicious breast lesions identified on diagnostic clinical ultrasound had lower oxygenation and higher hemoglobin concentration than the surrounding normal breast tissue. Furthermore, histopathologic-proven malignant breast tumors had a lower differential hemoglobin contrast (that is, the difference of hemoglobin concentration variability between the suspicious breast lesion and the normal breast parenchyma located remotely elsewhere within the ipsilateral breast) as compared with histopathologic-proven benign breast lesions. Conclusion: The proposed dynamic near-infrared imaging schema has the potential to differentiate benign processes from those of malignant breast tumors. Further development and refinement of the dynamic imaging device and additional subsequent clinical testing are necessary for optimizing the accuracy of detection

Systems and methods for physiological signal enhancement and biometric extraction using non-invasive optical sensors

A system and method for signal processing to remove unwanted noise components including: (i) wavelength-independent motion artifacts such as tissue, bone and skin effects, and (ii) wavelength-dependent motion artifact/noise components such as venous blood pulsation and movement due to various sources including muscle pump, respiratory pump and physical perturbation. Disclosed are methods, analytics, and their uses for reliable perfusion monitoring, arterial oxygen saturation monitoring, heart rate monitoring during daily activities and in hospital settings and for extraction of physiological parameters such as respiration information, hemodynamic parameters, venous capacity, and fluid responsiveness. The system and methods disclosed are extendable to include monitoring platforms for perfusion, hypoxia, arrhythmia detection, airway obstruction detection and sleep disorders including apnea.Board of Regents, University of Texas Syste

Aerospace medicine and biology: A continuing bibliography with indexes

This bibliography lists 148 reports, articles and other documents introduced into the NASA scientific and technical information system in December 1984