Non-invasive Method For Continuous Monitoring Research Articles

Seasonal swarming behavior of Myotis bats revealed by integrated monitoring, involving passive acoustic monitoring with automated analysis, trapping, and video monitoring.

Bat abundance, diversity, and behavior can be monitored by capturing bats for identification and measurement in the hand, but this has several disadvantages. These include disturbance to the bats, which limits the frequency with which captures can be made at an individual capture site, and potentially alters the behaviors being studied. Infrared video monitoring, passive acoustic recording and automated analysis and identification of bat calls offers an alternative set of noninvasive methods for monitoring bats. In this study, we examine the effectiveness of acoustic monitoring in comparison with capture‐based and video monitoring of seasonal swarming behavior among several species of Myotis bats in southern Britain. We applied these complementary approaches to describe seasonal, overnight, and species‐specific variation in swarming behavior in a multispecies community of Myotis bats. We show that the three monitoring approaches have advantages and disadvantages for different tasks, but can be viewed as highly complementary methods for addressing different types of research questions. In our study of swarming behavior, capture and examination of bats in the hand was necessary for measuring sex ratios, reproductive status, and even for confirmation of species identification for some difficult to separate taxa. Capture is also an essential aspect of tagging bats for individual identification and tracking studies. Video monitoring is useful for understanding the behavior of bats at swarming sites, and measuring the flux of individuals into and out of roosting or swarming sites. Passive acoustic monitoring is a valuable noninvasive method for continuous monitoring of within‐night, seasonal, and between‐year variation in the abundance of bat calls. These can be used as an index of variation in relative abundance within—but not between—bat species.

Near Infrared Spectroscopy For Cerebral Hemodynamic Monitoring During Carotid Endarterectomy Under General Anesthesia

Background:Near infrared spectroscopy (NIRS) is a noninvasive method for continuous monitoring of cerebral oxygenation.Objective:To describe the intraoperative behavior of NIRS variables used to evaluate hemodynamic response in patients with atherosclerotic disease undergoing carotid endarterectomy under general anesthesia.Methods:Fifteen volunteers with atherosclerotic carotid disease with indications for endarterectomy were evaluated. After selection of patients, carotid stenosis was confirmed by appropriate diagnostic methods. NIRS was used for intraoperative monitoring. The variables total hemoglobin (Hb), oxygenated hemoglobin (O2Hb), deoxygenated hemoglobin (HHb), and regional oxygen saturation (rSO2) were evaluated at three intraoperative time points: before, during, and after carotid clamping.Results and Discussion:Measurements recorded by NIRS showed that, during the first 5 min of clamp time, patients experienced a decline in O2Hb levels, an increase in HHb levels, and a marked decrease in rSO2. Hb remained constant throughout the procedure. At the post-clamping time point, HHb, O2Hb, and rSO2returned to patterns similar to those observed before clamping.Conclusion:NIRS was able to reliably and accurately identify the three stages of carotid endarterectomy and may predict the risk of cerebral hypoxia during carotid clamping under general anesthesia.

Evaluation of fingertip pulse oximeters for monitoring haemoglobin oxygen saturation in arterial blood and pulse rate in isoflurane‐anaesthetised horses breathing greater than 90 percent oxygen

SummaryBackgroundPulse oximetry is a noninvasive method for continuous monitoring of oxygen saturation (SpO2) and pulse rate (PR) used in equine anaesthesia. Despite species differences in the oxyhaemoglobin dissociation curve, pulse oximeters validated for humans are commonly used in veterinary medicine. These devices are expensive and at an increased risk for damage when used for equine anaesthesia. Human fingertip pulse oximeters (FPO) may be useful as an inexpensive alternative to standard devices.ObjectivesEvaluate accuracy and repeatability of FPOs applied to tongues of anaesthetised horses breathing >90% oxygen.Study designProspective clinical study.MethodsDuplicate SpO2 and PR measurements from eight pulse oximeters (PO; seven FPOs and reference PO) placed in random order on tongues of horses under inhalational anaesthesia were recorded. A standard portable PO (RPO) was used as reference SpO2 and invasive blood pressure trace or manual pulse palpation as reference PR. Nonparametric Bland‐Altman analysis was performed. Acceptable coefficient of repeatability (CR) value was ≤6% SpO2. Agreements were accepted if limits of agreement were ≤ ±3% difference in SpO2 and ≤ ±10% relative difference in PR. Only PR values between 25 and 50 beats per minute and their corresponding SpO2 measurements were used for agreement analysis.ResultsSpO2 repeatability and agreement were unacceptable for all devices. The agreement of PR measurements was acceptable for one FPO and the RPO.Main limitationsUtilisation of devices designed for the human oxyhaemoglobin dissociation curve, high number of absent or erroneous readings, use of healthy horses, small sample size, unavailability of co‐oximetry, lack of a desaturation protocol and difficulty with proper placement of FPOs on horse tongues are all considered limitations in this study.ConclusionsAccuracy of FPOs used in anaesthetised horses was poor. Their use in equine anaesthesia for SpO2 monitoring is not recommended, but some models may be considered for continuous PR monitoring in conjunction with intermittent manual confirmation.

Correlation Between Ambulatory Blood Pressure Monitoring and Office Blood Pressure Measurement in Patients with Hypertension: A Community Study

BackgroundThe current gold standard for blood pressure (BP) measurements is based on office BP measurements (OBPMs) by a sphygmomanometer or a digital device. Ambulatory BP measurement (ABPM) is a noninvasive method for continuous monitoring of BP over a period during routine activities of the patient. Thus, ABPM offers multiple BP readings during the patients’ daily routine as compared to the single reading by OBPM at rest. A good correlation exists between mean 24-hour BP readings and the prediction of cardiovascular events. The present multicenter observational study was aimed to assess the correlation between ABPM and OBPM in patients with newly diagnosed, controlled, or uncontrolled hypertension in the community setting.Our hypothesis was to test if ABPM provides any further value in those hypertensive patients in whom the office blood pressure levels are controlled. A supplementary hypothesis was whether obtaining ABPM in patients with newly diagnosed or uncontrolled hypertension yields any value over and beyond OBPM. Another objective was to find out the applicability of ABPM in the community setting where the medical care is provided by primary care family physicians and not by specialists. Materials and MethodsMaterials and Methods A total of 1000 patients were analysed for this study. Those with controlled hypertension were assigned to Group A, and those with newly diagnosed/untreated hypertension comprised Group B. Group A was followed up during Visit 2 and Group B was followed up during Visit 2 and either Visit 3 or Visit 4 to assess the BP measurements by ABPM and OBPM. ResultsThe correlation between ABPM and OBPM showed minimal variation in the BP readings of Group A subjects at Visit 2. A variation in BP readings was observed in Group B at Visit 2. Furthermore, the correlation was established between ABPM and OBPM noted for Group B subjects during Visit 3, and minimal variation was noted during Visit 4. ConclusionsConclusions A good correlation was observed between ABPM and OBPM during both visits in patients in Groups A and B. However, a notable variation was noted in the diastolic BP readings. Thus, large-scale clinical studies are required to detect the prevalence of hypertension, masked hypertension, and dipping patterns associated with hypertension and other related medical co-morbidities.

Thermal imaging applications in neonatal care: a scoping review

BackgroundIn neonatal care, assessment of the temperature of the neonate is essential to confirm on-going health, and as an early signal of potential pathology. However, some methods of temperature assessment involve disturbing the baby, disrupting essential sleep patterns, and interrupting maternal/infant interaction. Thermal imaging is a completely non-invasive and non-contact method of assessing emitted temperature, but it is not a standard method for neonatal thermal monitoring. To examine the potential utility of using thermal imaging in neonatal care, we conducted a comprehensive systematic scoping review of thermal imaging applications in this context.MethodsWe searched EMBASE, MEDLINE and MIDIRS.ResultsFrom 442 hits, 21 met the inclusion criteria and were included in the review. A significant number (n = 9) were published in the last 8 years. All the studies were observational studies, with 20 out of 21 undertaken in North America or Europe. Most of them had small cohorts (range 4–29 participants). The findings were analysed narratively, to establish the issues identified in the included studies. Five broad themes emerged for future examination. These were: general thermal physiology; heat loss and respiratory monitoring; identification of internal pathologies, including necrotising enterocolitis; other uses of thermal imaging; and technical concerns. The findings suggest that thermal imaging is a reliable and non-invasive method for continuous monitoring of the emitted temperature of the neonates, with potential for contributing to the assurance of wellbeing, and to the diagnosis of pathologies, including internal abnormalities. However, the introduction of thermal imaging into everyday neonatology practice has several methodological challenges, including environmental parameters, especially when infants are placed in incubators or open radiant warmers.ConclusionIn conclusion, although the first attempt at using thermal imaging in neonatal care started in the early-1970s, with promising results, and subsequent small cohort studies have recently reinforced this potential, there have not been any large prospective studies in this area that examine both the benefits and the barriers to its use in practice.

Experimental study on the detection of cerebral hemorrhage in rabbits based on broadband antenna technology

Hematoma enlargement often occurs in patients with spontaneous intracerebral hemorrhage (ICH), so it is necessary to monitor the amount of intracranial hemorrhage in patients after admission. At present, the commonly used intracranial pressure (ICP) method has the disadvantages of trauma and infection, and the Computer Tomography (CT) method cannot achieve continuous monitoring. So it is urgent to develop a non-contact and non-invasive method for continuous monitoring of cerebral hemorrhage. The dielectric properties of blood are different from those of brain tissue, so the hematoma will affect the amplitude and phase of the electromagnetic waves passing through the head. A microstrip antenna was designed to construct the detection system for cerebral hemorrhage. Based on the animal model of acute cerebral hemorrhage, the detecting experiment was carried out on thirteen rabbits. Each rabbit had three bleeding states: 1, 2, and 3 ml, which represented the severity of cerebral hemorrhage. According to the measured data of high dimension and small sample, the support vector machine (SVM) algorithm was used to assess the severity of cerebral hemorrhage. According to simulation results, the antenna’s forward radiation was 5 dB larger than the backward radiation, which ensured the antenna being not affected by external signals during the measurement. According to test results, the −10 dB workband of the antenna was 1.55–2.05 GHz and the frequency range of the transmission parameters S21 above −30 dB is 1.2 − 3 GHz. In the animal experiment, the phase difference of Transmission coefficient S21 was gradually increased with the increase of bleeding volume. Through the classification of 39 bleeding states of the 13 rabbits, the total accuracy was about 77%. Through animal experiments, the feasibility of detection method has been proved. But the classification accuracy need to be further improved. The detection system is based on broadband antenna has the potential to realize non-contact, non-invasive and continuous monitoring for cerebral hemorrhage.

RF91 USE OF NIRS AND REFLECTANCE PULSE OXIMETRY AS A MONITORING IN DISTAL PERFUSION OF THE LIMB DURING PERIPHERAL ECMO.

Background and aim: One of the biggest complications in patients treated with venoarterial ECMO is lower extremity ischemia, site of the peripheral cannulation. The ELSO database reports a 5% incidence of ischemic leg complications in patients with peripheral va-ECMO, leading to leg amputation in 1% of cases. The objective of the study is to optimize the perfusion of the cannulated limb for the reduction of the incidence of ischemia, pacing a distal perfusion catheter (8 Fr) in the superficial femoral artery, before the insertion of the deep femoral artery and monitoring of tissue oxygen saturation by NIRS and reflectance pulse oxymetry. Methods: Our study includes the analysis of the experience on a group of 9 patients in which tissue saturation was monitored by NIRS (group A) and another group that includes patients on whom the distal flow of the limb has been periodically detected by Eco Doppler SD2, without monitoring of tissue saturation (group B). Results: In the experience of group B a late diagnosis of ischemia of the cannulated limb was found despite the distal perfusion. In group A NIRS monitoring allowed to readily diagnose a hypoperfusion, detected with a variation of saturation > 10% with respect to the tissue saturation of the contralateral limb and the basal value, resolving it with the immediate repositioning distal perfusion cannula. Conclusions: We conclude that transcutaneous NIRS and reflectance pulse oximetry may be an effective non-invasive method for continuous monitoring of leg perfusion in patients treated with peripheral ECMO and distal limb reperfusion.

Rectal and Bladder Temperatures vs Forehead Core Temperatures Measured With SpotOn Monitoring System.

Methods and frequency of temperature monitoring in intensive care unit patients vary widely. The recently available SpotOn system uses zero-heat-flux technology and offers a noninvasive method for continuous monitoring of core temperature of critical care patients at risk for alterations in body temperature. To evaluate agreement between and precision of a zero-heat-flux thermometry system (SpotOn) and continuous rectal and urinary bladder thermometry during fever and defervescence in adult patients in intensive care units. Prospective comparison of SpotOn vs rectal and urinary bladder thermometry in eligible patients enrolled in a randomized clinical trial on the effect of acetaminophen on core body temperature and hemodynamic status. A total of 748 paired temperature measurements from 38 patients who had both SpotOn monitoring and either continuous rectal or continuous bladder thermometry were analyzed. Temperatures during the study were from 36.6°C to 39.9°C. The mean difference for SpotOn compared with bladder thermometry was -0.07°C (SD, 0.24°C; 95% limits of agreement, ± 0.47°C [-0.54°C, 0.40°C]). The mean difference for SpotOn compared with rectal thermometry was -0.24°C (SD, 0.29°C; 95% limits of agreement, ± 0.57°C [-0.81°C, 0.33°C]). Most differences in temperature between methods were within ± 0.5°C in both groups (96% bladder and 85% rectal). The SpotOn thermometry system has excellent agreement and good precision and is a potential alternative for noninvasive continuous monitoring of core temperature in critical care patients, especially when alternative methods are contraindicated or not available.

Modeling of heart sound morphology and analysis of the morphological variations induced by respiration

In this study, each peak/valley of a heart sound was modeled by a Gaussian curve and characterized by amplitude, timing, and supporting width. This model was applied to analyze the morphological variations induced by respiration in 12 subjects. It was observed that the morphology exhibited regular behaviors with respiration. The amplitude of the prominent peaks and valleys of S2 (the second heart sound) were commonly attenuated during expiration and were accentuated during inspiration whereas no consistent observations were obtained for S1 (the first heart sound). The supporting width of S1 commonly decreased with expiration and increased with inspiration whereas the supporting width of S2 displayed no significant changes during respiration. For all subjects, the delay of S1 increased during inspiration and decreased during expiration. However, the delay of the aortic component increased during expiration and decreased during inspiration. The pulmonary component of S2 was observed in 7 of 12 subjects, and the delay was opposite to that of the aortic component. The opposing delays yielded a splitting between the two components of S2 that increased during inspiration and decreased during expiration. The delay pattern was the most consistent observation in all subjects. These results suggest that a quantitative analysis of morphological variations, particularly the delay pattern, could be used as a non-invasive continuous monitoring method of hemodynamic change during respiratory cycles.

Near-Infrared Spectroscopy Monitoring of the Spinal Cord During Type B Aortic Dissection Surgery

Near-infrared spectroscopy (NIRS) is a noninvasive continuous monitoring method for measuring the oxyhemoglobin saturation of the brain tissue. NIRS monitoring can suggest neuronal hypoxia in the frontal-brain before irreversible impairment of cellular metabolism. We report two cases of Type B aortic dissection surgery in which spinal regional perfusion monitoring was performed by placing two NIRS sensors on the back-skin through T6-T8 and T9-T11 vertebraes.

Blood Flow Analysis of the Head and Lower Limbs by the Laser Doppler Blood Flowmeter During LDL Apheresis

The presence of peripheral arterial disease substantially increases the risk for both morbidity and mortality among end-stage renal disease patients. Low-density lipoprotein (LDL) apheresis has been also applied for the treatment of peripheral arterial disease to reduce LDL levels, resulting in the improvement of the blood flow to the ischemic limbs. In this study, we investigated the continuous changes of the tissue blood flows in the lower limbs and head during LDL-apheresis treatment by a non-invasive method (the non-invasive continuous monitoring method (NICOMM) system). In this study, the tissue blood flow in both the head and lower limbs showed a significantly enhancement from before to after treatment. The tissue blood flow in the lower limbs showed a significantly larger improvement than that in the head. The short-term effects of LDL apheresis were confirmed by using the NICOMM system; thus, this system will be useful for the determination of the appropriate schedule of LDL apheresis for long-term effectiveness.

Analysis of Hemodynamics During Blood Purification Therapy Using a Newly Developed Noninvasive Continuous Monitoring Method

Advancement in blood purification therapy extends not only to consoles and dialyzers, but also to patient management during blood purification therapy. However, no monitor has been devised for hemodynamics during blood purification therapy that is carried out continuously and non-invasively. By studying the laser Doppler flowmeter (LDF), we have developed a probe that can continuously measure changes in blood flow in tissues of the head and lower extremities during blood purification therapy. By applying the improved LDF, we have developed a non-invasive continuous monitoring method (NICOMM). Hemodynamics in various types of blood purification therapies were also studied by simultaneously measuring with an automatic oscillometric sphygmomanometer.

Development of a new method for monitoring blood purification: The blood flow analysis of the head and foot by laser Doppler blood flowmeter during hemodialysis

The management of blood pressure in hemodialysis patients greatly affects not only their quality of life, but also the duration of dialysis (dialysis life). Approximately 25% of dialysis patients suffer from continuous low blood pressure; however, the relationship between blood pressure and blood flow during dialysis has not been established. We hypothesized that with complete extracorporeal circulation, blood purification methods might affect blood flow, resulting in a change in blood pressure. The purpose of this study was to develop a noninvasive continuous monitoring method (NICOMM) as a microcirculation monitor by devising a laser-Doppler flowmeter (LDF) system with a wavelength of 780 nm. The aim was to use this system to simultaneously measure blood flow rate in both the head and the foot during dialysis and to determine the effectiveness of NICOMM by measuring blood flow and arterial distensibility. When exhibiting a significant decline in blood pressure at 240 min after the initiation of hemodialysis, a drop in blood flow in parallel with the blood pressure fall was recorded by the LDF. However, no changes were observed, in the readings by a continuous hematocrit monitor (Crit-Line monitor, CLM). Furthermore, a significant correlation was registered between mean arterial blood pressure and blood flow rate in the earlobe tissue from 180 min after the initiation of hemodialysis to the completion of hemodialysis (p < 0.001, r = 0.78). Comparisons were made by measuring vascular dehydration using the CLM. NICOMM showed more stable readings than the CLM in monitoring blood flow in response to changes in blood pressure.

Detection of brain oedema using magnetic induction tomography: a feasibility study of the likely sensitivity and detectability

The detection and continuous monitoring of brain oedema is of particular interest in clinical applications because existing methods (invasive measurement of the intracranial pressure) may cause considerable distress for the patients. A new non-invasive method for continuous monitoring of an oedema promises the use of multi-frequency magnetic induction tomography (MIT). MIT is an imaging method for reconstructing the changes of the conductivity Δκ in a target object. The sensitivity of a single MIT-channel to a spherical oedematous region was analysed with a realistic model of the human brain. The model considers the cerebrospinal fluid around the brain, the grey matter, the white matter, the ventricle system and an oedema (spherical perturbation). Sensitivity maps were generated for different sizes and positions of the oedema when using a coaxial coil system. The maps show minimum sensitivity along the coil axis, and increasing values when moving the perturbation towards the brain surface. Parallel to the coil axis, however, the sensitivity does not vary significantly. When assuming a standard deviation of 10−7 for the relative voltage change due to the system's noise, a centrally placed oedema with a conductivity contrast of 2 with respect to the background and a radius of 20 mm can be detected at 100 kHz. At higher frequencies the sensitivity increases considerably, thus suggesting the capability of multi-frequency MIT to detect cerebral oedema.

The assessment of cerebral oxygenation during carotid endarterectomy utilising near infrared spectroscopy

Near infrared spectroscopy is a non-invasive method for continuous monitoring of tissue oxygenation. In 11 patients undergoing unilateral carotid endarterectomy, changes in cerebral oxygenation following carotid cross-clamping and declamping detected by a near infrared spectrometer were compared with corresponding changes in ipsilateral middle cerebral artery flow velocity measured by transcranial Doppler ultrasonography. Spectroscopic traces were obtained in all patients but adequate Doppler signals in only eight. Changes in cerebral haemoglobin oxygenation correlated closely (r = 0.908, p < 0.001) with changes in middle cerebral artery velocity. The near infrared spectrometer was also sensitive to the changes in cerebral haemodynamics due to intraoperative hypo- and hypertensive episodes. No evidence of cerebral intracellular hypoxia was seen and all patients made an uneventful recovery. Near infrared spectroscopy compares well with transcranial Doppler ultrasound as a monitor of cerebral function during carotid endarterectomy and may have a future role in the elucidation of cerebral perfusion and oxygenation changes following surgery.

Optimizing ventilatory settings using pulse oximetry in the transition between life and death

In the patient with catastrophic lung disease intra- and extrapulmonary factors interact to determine the O2-delivery to the peripheral lifethreathened organs. The therapeutic strategy will take into account both settings on the ventilator that are not harmful to the patient i.e. avoiding high peak airway pressures and high inspired oxygen fractions and circulatory support keeping the cardiac output adequate. Usually the arterial blood gases are frequently monitored as parameters determining optimal therapy. Recently pulse oximetry has been suggested as a noninvasive continuous monitoring method. It could be looked upon as an indicator and monitor of both ventilatory and circulatory optimality, because the parameter tells what “the sensor sees.” This might not be identical to the “true arterial saturation”, but it can be argued that this does not matter as long as the trend observed is useful in therapeutic decision making.In this study 25 patients with catastrophic lung disease i.e. a) panlobar alveolar infiltrates, b) a PaO2 >7.00 kPa with an FIO2 > 0.8 with 15 cm H2O PEEP and a cardiac index above 3.5 L/min/m2 and c) an effective compliance below 25 ml/cm H2O were studied and ventilatory and circulatory adjustments were made in order to reduce peak airway pressure to below 50 cm H2O and the FIO2 to below 0.6. Fourteen patients were randomised to monitoring with pulse oximetry and eleven to conventional arterial blood gas analysis. Using pulse oximetry the median time for optimization was 45 min with a range of 20–120, without pulse oximetry the median time was 95 min with range 60–240, p <0.05.It is concluded that pulse oximetry is a fast, reliable index of peripheral O2-delivery and can be regarded a “new parameter” in optimizing ventilatory strategy.