Comparison of tracheal versus esophageal temperatures during laparoscopic surgery.

PURPOSE: Recently, endotracheal tubes with an embedded temperature sensor in the inner surface of the tube cuff (temperature tracheal tubes) have been developed. We sought to assess whether temperature tracheal tubes show a good agreement with esophageal temperature probes during surgery. METHODS: We enrolled 40 patients who underwent laparoscopic surgery in an observational study. The tracheas of all patients were intubated with a temperature tracheal tube, and an esophageal temperature probe was inserted into the esophagus. Tracheal and esophageal temperatures were recorded at 15-min intervals until the end of surgery. Temperatures from both devices were analyzed using Bland-Altman analysis, four-quadrant plots, and polar plots. RESULTS: We analyzed 261 data points from 36 patients. Temperatures ranges were 34.2 °C to 36.6 °C for the tracheal temperature tube and 34.7 °C to 37.2 °C for the esophageal temperature probe. Bland-Altman analysis showed an acceptable agreement between the two devices, with an overall mean bias (95% limit of agreement) of -0.3 °C (-0.8 °C to 0.1 °C) and a percentage error of 3%; the trending ability (temperature changes over time) between the two devices showed a concordance rate of 94% in four-quadrant plot (cut-off ≥ 92%), but this was higher than the acceptable mean angular bias of 177° (cut-off < ± 5°) and radial limits of agreement of 52° (cut-off < ± 30°) in the polar plot. Bronchoscopy during extubation and patient interviews at six hours postoperatively revealed no serious injuries related to the use of the temperature tracheal tube. CONCLUSION: The temperature tracheal tube showed an acceptable overall mean bias of -0.3 °C and a percentage error of 3%, but incompatible trending ability with the esophageal temperature probe. STUDY REGISTRATION: cris.nih.go.kr (KCT0007265); 22 April 2022.

RéSUMé: OBJECTIF: Récemment, des sondes endotrachéales munies d'un capteur de température intégré dans la surface interne du ballonnet de la sonde (sondes thermiques trachéales) ont été mises au point. Nous avons cherché à évaluer si les sondes trachéales de température montraient une bonne concordance avec les sondes thermiques œsophagiennes pendant la chirurgie. MéTHODE: Nous avons recruté 40 patient·es ayant bénéficié d'une chirurgie par laparoscopie dans le cadre d'une étude observationnelle. Les trachées de tou·tes les patient·es ont été intubées à l'aide d'une sonde trachéale de température et une sonde thermique œsophagienne a été insérée dans l'œsophage. Les températures trachéale et œsophagienne ont été enregistrées à des intervalles de 15 minutes jusqu'à la fin de la chirurgie. Les températures des deux appareils ont été analysées à l'aide d'une analyse de Bland-Altman, de diagrammes à quatre quadrants et de diagrammes polaires. RéSULTATS: Nous avons analysé 261 points de données provenant de 36 patient·es. Les plages de température allaient de 34,2 °C à 36,6 °C pour la sonde trachéale de température et de 34,7 °C à 37,2 °C pour la sonde thermique œsophagienne. L'analyse de Bland-Altman a montré une concordance acceptable entre les deux dispositifs, avec un biais moyen global (limite de 95 % de la concordance) de −0,3 °C (−0,8 °C à 0,1 °C) et un pourcentage d'erreur de 3 %; la capacité de tendance (changements de température au fil du temps) entre les deux dispositifs a montré un taux de concordance de 94 % dans un diagramme à quatre quadrants (limite ≥ 92 %), mais cette capacité était plus élevée que le biais angulaire moyen acceptable de 177° (limite < ± 5°) et que les limites radiales de l'accord de 52° (limite < ± 30°) dans le diagramme polaire. La bronchoscopie réalisée lors de l'extubation et les entretiens avec les patient·es six heures après l'opération n'ont révélé aucune blessure grave liée à l'utilisation de la sonde trachéale de température. CONCLUSION: La sonde trachéale de température a montré un biais moyen global acceptable de −0,3 °C et un pourcentage d'erreur de 3 %, mais une capacité de tendance incompatible avec la sonde thermique œsophagienne. ENREGISTREMENT DE L'éTUDE: cris.nih.go.kr (KCT0007265); 22 avril 2022.

How Can We Measure Alcohol Outlet Density Around Schools? A Comparison Between Two Buffer-Based Methods.

Measuring the density of alcohol outlets around schools is a critical step towards understanding the drivers of drinking among adolescents. Different methodologies have been used in the literature for this purpose, but the implications of using one methodology or another have not been clearly assessed. Our aim was to compare different methods to measure alcohol outlet density and highlight under which characteristics of the environment might be best using each approach. We used Geographic Information Systems to geolocate schools (n = 576) and alcohol outlets (n = 21,732) in Madrid. We defined the density of alcohol outlets as the number of establishments within an area of 400 m around schools measured using two buffering methods: crow flies' and street network distances. We evaluated the agreement between both methods visually and through regression models, including street connectivity, population density, and density of recreational venues as predictors of disagreement. The density of alcohol outlets around schools was higher using crow flies' distances compared to street network distances. The differences between methodologies were wider in areas of higher density of outlets, especially in the downtown areas, where there are higher population density and street connectivity. Our results suggest that the spatial characteristics and morphology of the study area (e.g., street connectivity and population density) should be considered when deciding the methodology to be used to measure alcohol outlet density. Future studies should explore the implications of different exposure measures in their association with drinking prevalence and consumption patterns among different geographical contexts.

Validity of Inertial Measurement Units to Measure Lower-Limb Kinematics and Pelvic Orientation at Submaximal and Maximal Effort Running Speeds.

Inertial measurement units (IMUs) have been validated for measuring sagittal plane lower-limb kinematics during moderate-speed running, but their accuracy at maximal speeds remains less understood. This study aimed to assess IMU measurement accuracy during high-speed running and maximal effort sprinting on a curved non-motorized treadmill using discrete (Bland-Altman analysis) and continuous (root mean square error [RMSE], normalised RMSE, Pearson correlation, and statistical parametric mapping analysis [SPM]) metrics. The hip, knee, and ankle flexions and the pelvic orientation (tilt, obliquity, and rotation) were captured concurrently from both IMU and optical motion capture systems, as 20 participants ran steadily at 70%, 80%, 90%, and 100% of their maximal effort sprinting speed (5.36 ± 0.55, 6.02 ± 0.60, 6.66 ± 0.71, and 7.09 ± 0.73 m/s, respectively). Bland-Altman analysis indicated a systematic bias within ±1° for the peak pelvic tilt, rotation, and lower-limb kinematics and -3.3° to -4.1° for the pelvic obliquity. The SPM analysis demonstrated a good agreement in the hip and knee flexion angles for most phases of the stride cycle, albeit with significant differences noted around the ipsilateral toe-off. The RMSE ranged from 4.3° (pelvic obliquity at 70% speed) to 7.8° (hip flexion at 100% speed). Correlation coefficients ranged from 0.44 (pelvic tilt at 90%) to 0.99 (hip and knee flexions at all speeds). Running speed minimally but significantly affected the RMSE for the hip and ankle flexions. The present IMU system is effective for measuring lower-limb kinematics during sprinting, but the pelvic orientation estimation was less accurate.

Statistical considerations for assessing precision of heterogeneous duplicate measurements: An application to pharmaceutical bioanalysis.

Duplicate analysis is a strategy commonly used to assess precision of bioanalytical methods. In some cases, duplicate analysis may rely on pooling data generated across organizations. Despite being generated under comparable conditions, organizations may produce duplicate measurements with different precision. Thus, these pooled data consist of a heterogeneous collection of duplicate measurements. Precision estimates are often expressed as relative difference indexes (RDI), such as relative percentage difference (RPD). Empirical evidence indicates that the frequency distribution of RDI values from heterogeneous data exhibits sharper peaks and heavier tails than normal distributions. Therefore, traditional normal-based models may yield faulty or unreliable estimates of precision from heterogeneous duplicate data. In this paper, we survey application of the mixture models that satisfactorily represent the distribution of RDI values from heterogeneous duplicate data. A simulation study was conducted to compare the performance of the different models in providing reliable estimates and inferences of percentile calculated from RDI values. These models are readily accessible to practitioners for study implementation through the use of modern statistical software. The utility of mixture models are explained in detail using a numerical example.

Utility of Ultrasound-Guided Attenuation Parameter for Grading Steatosis With Reference to MRI-PDFF in a Large Cohort.

BACKGROUND & AIMS: Ultrasound-guided attenuation parameter (UGAP) is recently developed for noninvasive evaluation of steatosis. However, reports on its usefulness in clinical practice are limited. This prospective multicenter study analyzed the diagnostic accuracy of grading steatosis with reference to magnetic resonance imaging-based proton density fat fraction (MRI-PDFF), a noninvasive method with high accuracy, in a large cohort. METHODS: Altogether, 1010 patients with chronic liver disease who underwent MRI-PDFF and UGAP were recruited and prospectively enrolled from 6 Japanese liver centers. Linearity was evaluated using intraclass correlation coefficients between MRI-PDFF and UGAP values. Bias, defined as the mean difference between MRI-PDFF and UGAP values, was assessed by Bland-Altman analysis. UGAP cutoffs for pairwise MRI-PDFF-based steatosis grade were determined using area under the receiver-operating characteristic curve (AUROC) analyses. RESULTS: UGAP values were shown to be normally distributed. However, because PDFF values were not normally distributed, they were log-transformed (MRI-logPDFF). UGAP values significantly correlated with MRI-logPDFF (intraclass correlation coefficient = 0.768). Additionally, Bland-Altman analysis showed good agreement between MRI-logPDFF and UGAP with a mean bias of 0.0002% and a narrow range of agreement (95% confidence interval [CI], -0.015 to 0.015). The AUROCs for distinguishing steatosis grade ≥1 (MRI-PDFF ≥5.2%), ≥2 (MRI-PDFF ≥11.3%), and 3 (MRI-PDFF ≥17.1%) were 0.910 (95% CI, 0.891-0.928), 0.912 (95% CI, 0.894-0.929), and 0.894 (95% CI, 0.873-0.916), respectively. CONCLUSIONS: UGAP has excellent diagnostic accuracy for grading steatosis with reference to MRI-PDFF. Additionally, UGAP has good linearity and negligible bias, suggesting that UGAP has excellent technical performance characteristics that can be widely used in clinical trials and patient care. (UMIN Clinical Trials Registry, Number: UMIN000041196).

Measurement of Cardiac Output Using an Ultrasonic Cardiac Output Monitor (USCOM) in Patients with Single-Ventricle Physiology.

We evaluate the validity of cardiac index (CI) measurements utilizing the Ultrasonic Cardiac Output Monitor (USCOM), a non-invasive Doppler ultrasound device, by comparing measurements to cardiac catheterization-derived CI measurements in patients with single-ventricle physiology. USCOM measurements were repeated three times for each patient at the beginning of a cardiac catheterization procedure for twenty-six patients undergoing elective pre-Glenn or pre-Fontan catheterization. CI was measured by USCOM and was calculated from cardiac catheterization data using Fick's method. Bland-Altman analysis for CI showed bias of 0.95 L/min/m2 with the 95% limits of agreement of - 1.85 and 3.75. Pearson's correlation coefficient was 0.89 (p < 0.001) indicating a strong positive relationship between USCOM and cardiac catheterization CI measurements. When excluding two patients with significant dilation of the neo-aortic valve (z-score > + 5), the bias improved to 0.66 L/min/m2 with the 95% limits of agreement of - 1.38 and 2.70. Percent error of limits of agreement was 34%. There was excellent intra-operator reproducibility of USCOM CI measurements with an intra-class coefficient of 0.96. We demonstrate the use of USCOM to measure CI in patients with single-ventricle physiology for the first time, showing acceptable agreement of the CI measurements between USCOM and cardiac catheterization with a high intra-operator reproducibility.

A Differential Inertial Wearable Device for Breathing Parameter Detection: Hardware and Firmware Development, Experimental Characterization.

Breathing monitoring is crucial for evaluating a patient's health status. The technologies commonly used to monitor respiration are costly, bulky, obtrusive, and inaccurate, mainly when the user moves. Consequently, efforts have been devoted to providing new solutions and methodologies to overcome these limitations. These methods have several uses, including healthcare monitoring, measuring athletic performance, and aiding patients with respiratory diseases, such as COPD (chronic obtrusive pulmonary disease), sleep apnea, etc. Breathing-induced chest movements can be measured noninvasively and discreetly using inertial sensors. This research work presents the development and testing of an inertia-based chest band for breathing monitoring through a differential approach. The device comprises two IMUs (inertial measurement units) placed on the patient's chest and back to determine the differential inertial signal, carrying out information detection about the breathing activity. The chest band includes a low-power microcontroller section to acquire inertial data from the two IMUs and process them to extract the breathing parameters (i.e., RR-respiration rate; TI/TE-inhalation/exhalation time; IER-inhalation-to-exhalation time; V-flow rate), using the back IMU as a reference. A BLE transceiver wirelessly transmits the acquired breathing parameters to a mobile application. Finally, the test results demonstrate the effectiveness of the used dual-inertia solution; correlation and Bland-Altman analyses were performed on the RR measurements from the chest band and the reference, demonstrating a high correlation (r¯ = 0.92) and low mean difference (MD¯ = -0.27 BrPM (breaths per minute)), limits of agreement (LoA¯ = +1.16/-1.75 BrPM), and mean absolute error (MAE¯ = 1.15%). Additionally, the experimental results demonstrated that the developed device correctly measured the other breathing parameters (TI, TE, IER, and V), keeping an MAE of ≤5%. The obtained results indicated that the developed chest band is a viable solution for long-term breathing monitoring, both in stationary and moving users.

Sample size determination in method comparison and observer variability studies.

The comparison of two quantitative measuring devices is often performed with the Limits of Agreement proposed by Bland and Altman in their seminal Lancet paper back in 1986. Sample size considerations were rare for such agreement analyses in the past, but recently several proposals have been made depending on how agreement is to be assessed and the number of replicates to be used. We have summarized recent developments and recommendations in various situations including a distinction between method comparison and observer variability studies. These include current state-of-the-art analysis of and reporting guidelines for agreement studies. General recommendations close the paper.

Cephalometric measurements performed on CBCT and reconstructed lateral cephalograms: a cross-sectional study providing a quantitative approach of differences and bias.

BACKGROUND: Cephalometric analysis is traditionally performed on skull lateral teleradiographs for orthodontic diagnosis and treatment planning. However, the skull flattened over a 2D film presents projection distortions and superimpositions to various extents depending on landmarks relative position. When a CBCT scan is indicated for mixed reasons, cephalometric assessments can be performed directly on CBCT scans with a distortion free procedure. The aim of the present study is to compare these two methods for orthodontic cephalometry. METHODS: 114 CBCTs were selected, reconstructed lateral cephalometries were obtained by lateral radiographic projection of the entire volume from the right and left sides. 2D and 3D cephalometric tracings were performed. Since paired t-tests between left and right-side measurements found no statistically significant differences, mean values between sides were considered for both 2D and 3D values. The following measurements were evaluated: PNS-A; S-N; N-Me; N-ANS; ANS-Me; Go-Me; Go-S; Go-Co; SNA, SNB, ANB; BaSN; S-N^PNS-ANS; PNS-ANS^Go-Me; S-N^Go-Me. Intraclass correlation coefficients, paired t-test, correlation coefficient and Bland-Altman analysis were performed to compare these techniques. RESULTS: The values of intra- and inter-rater ICC showed excellent repeatability and reliability: the average (± SD) intraobserver ICCs were 0.98 (± 0.01) and 0.97(± 0.01) for CBCT and RLCs, respectively; Inter-rater reliability resulted in an average ICC (± SD) of 0.98 (± 0.01) for CBCT and 0.94 (± 0.03) for RLC. The paired t-tests between CBCT and reconstructed lateral cephalograms revealed that Go-Me, Go-S, PNS-ANS^Go-Me and S-N^Go-Me measurements were statistically different between the two modalities. All the evaluated sets of measurements showed strong positive correlation; the bias and ranges for the 95% Limits of Agreement showed higher levels of agreement between the two modalities for unpaired measurements with respect to bilateral ones. CONCLUSION: The cephalometric measurements laying on the mid-sagittal plane can be evaluated on CBCT and used for orthodontic diagnosis as they do not show statistically significant differences with those measured on 2D lateral cephalograms. For measurements that are not in the mid-sagittal plane, the future development of specific algorithms for distortion correction could help clinicians deduct all the information needed for orthodontic diagnosis from the CBCT scan.

Test-retest reliability and practice effect of the Leuven Perceptual Organisation Screening Test.

AbstractVisual diagnostic tests must have a high degree of consistency in their measurements (high reliability) to ensure accurate assessment of perceptual abilities. The current study assessed test-retest reliability and practice effects in the Leuven Perceptual Organisation Screening Test (L-POST) in 144 healthy volunteers, with time intervals between 0 and 756 days. We used Pearson's and intraclass correlation analysis, Bland-Altman analysis and multilevel modelling. Results from our analyses converged and supported an adequate reliability of the L-POST. Multilevel modelling demonstrated an absence of practice effect, suggesting that the L-POST is suitable for repeat administration. This study suggests that the L-POST has adequate reliability and is suitable for repeat administration even at short intervals. This study provides the basis for a more systematic evaluation for neuropsychological assessments, which can lead to the development of more reliable assessment batteries.

Which Histometric Analysis Approach Is More Reliable for Assessing Histological Bone Tissue Samples?

This study aims to evaluate the grid of Merz and ImageJ methods for histometric quantification, verifying which is more reliable and defining which is most suitable based on the time required to perform. Thirty histological samples of maxillary sinuses grafted with xenografts were evaluated using an optical light microscope attached to an image capture camera and connected to a microcomputer. The images were digitalized and recorded as a TIFF image, and the new bone formation was evaluated using the grid of Merz and ImageJ. The Bland-Altman analysis was used to identify the agreement between the methods and determine suitable future research options. The timing of the quantification was also performed to identify a possible advantage. The mean value for the quantification analysis timing for the grid of Merz was 194.9 ± 72.0 s and for ImageJ was 871.7 ± 264.4, with statistical significance between the groups (p = 0.0001). The Bland-Altman analysis demonstrated a concordance between the methods, due to the bias being next to the maximum concordance (-1.25) in addition to the graphic showing the scattering points next to the mean of differences and inside of limits of agreement. Thus, it was demonstrated that the grid of Merz presents reliable outcomes and advantages over the ImageJ methodology regarding the time spent to contour the areas of interest.

Saliva for diagnosis of SARS-CoV-2: First report from India.

There are very few studies in search of an alternate and convenient diagnostic tool which can substitute nasopharyngeal swab (NPS) specimen for detection of SARS-CoV-2. In the study we analyzed, the comparison and agreement between the feasibility of using the saliva in comparison to NPS for diagnosis of SARS-CoV-2. A total number of 74 patients were enrolled for this study. We analyzed and compared the NPS and saliva specimen collected within 48 h after the symptom onset. We carried out real-time quantitative polymerase chain reaction, gene sequencing for the detection and determination SARS-CoV-2 specific genes. Phylogenetic tree was constructed to establish the isolation of viral RNA from saliva. We used the Bland-Altman model to identify the agreement between two specimens. This study showed a lower cycle threshold (CT ) mean value for the detection of SARS-CoV-2 ORF1 gene (mean, 27.07; 95% confidence interval [CI], 25.62 to 28.52) in saliva methods than that of NPS (mean 28.24; 95% CI, 26.62 to 29.85) specimen although the difference is statistically nonsignificant (p > .05). Bland-Altman analysis produced relatively smaller bias and high agreement between these two clinical specimens. Phylogenetic analysis with the RdRp and S gene confirmed the presence of SARS-CoV-2 in the saliva samples. Saliva represented a promising tool in COVID-19 diagnosis and the collection method would reduce the exposure risk of frontline health workers which is one of the major concerns in primary healthcare settings.

Validity of ultrasonography-derived predictions for estimating skeletal muscle volume: a systematic literature review.

BACKGROUND: The amount of muscle volume (MV) varies between individuals and is important for health, well-being and performance. Therefore, the monitoring of MV using different imaging modalities is important. Magnetic resonance imaging (MRI) is considered the gold standard, but is not always easily accessible, and the examinations are expensive. Ultrasonography (US) is a much less expensive imaging method widely used to measure changes in muscle thickness (MT). Whether MT may translate into MV needs further investigation. PURPOSE: The aim of this review is to clarify whether US-derived equations based on MT predict MV based on MRI. METHODS: A systematic literature review was conducted according to the PRISMA statement, searching the electronic databases PubMed, CINAHL and Web of Science, for currently published equations to estimate MV with US. RESULTS: The literature search resulted in 363 citations. Twelve articles met the eligibility criteria. Ten articles scored eight out of eleven on QUADAS and two scored nine. Thirty-six prediction equations were identified. R values ranged between 0.53 and 0.961 and the standard error of the estimate (SEE) ranged between 6 and 12% for healthy adult populations, and up to 25.6% for children with cerebral palsy. Eight studies evaluated the results with a Bland-Altman plot and found no systematic errors. The overall strength and quality of the evidence was rated "low quality" as defined by the GRADE system. CONCLUSIONS: The validity of US-derived equations based on MT is specific to the populations from which it is developed. The agreement with MV based on MRI is moderate with the SEE ranging between 6 and 12% in healthy adult populations. Suggestions for future research include investigations as to whether testing positions or increasing the number of measuring sites could improve the validity for prediction equations.

Evaluation of point-of-care testing device for anemia detection: A cross-sectional method comparison study from Thailand.

BACKGROUND: A comparison study is crucial before launching a new medical device; therefore, we compared the Mission Ultra Hb Testing System with the Sysmex XN-3000 automated hematology analyzer in Thai adult males and non-pregnant adult females. METHODS: Parallel studies were conducted using discarded venous K2-ethylenediaminetetraacetic acid samples from participants requiring hematological investigations. According to the World Health Organization criteria, the participants were categorized as overall, anemia, and non-anemia for analysis. RESULTS: Three hundred participants were included in this study. In all participants, near-perfect correlation and agreement were observed between the two methods for Hb measurement (r = 0.963, p < 0.001) with an interclass correlation coefficient (ICC) of 0.981 (95% confidence interval [CI]: 0.976-0.985) and Hct measurement (r = 0.941, p < 0.001) with an ICC of 0.965 (95% CI: 0.956-0.972). The sensitivity and specificity of the device in detecting anemia were 86.2% (95% CI: 79.7-91.2) and 98.6% (95% CI: 95.2-99.8), respectively. The area under the curve was 0.976 (95% CI: 0.963-0.989). The device showed average biases of 0.76 g/dl (95% limits of agreement [LOA]: -1.03 to 2.54) for Hb measurement and -2.73% (95% LOA: -9.28 to 3.82) for Hct measurement in all participants. CONCLUSION: Agreement between the Mission Ultra Hb Testing System and Sysmex XN-3000 was observed. The device was excellent for detecting anemia. However, the essential evidence showing biases of the Hb and Hct measurements obtained from the device was revealed. Laboratory interpretation should be carefully performed, particularly at the near cut-off values.

Comparison of the Performance of the Leap Motion ControllerTM with a Standard Marker-Based Motion Capture System.

Over the last few years, the Leap Motion Controller™ (LMC) has been increasingly used in clinical environments to track hand, wrist and forearm positions as an alternative to the gold-standard motion capture systems. Since the LMC is marker-less, portable, easy-to-use and low-cost, it is rapidly being adopted in healthcare services. This paper demonstrates the comparison of finger kinematic data between the LMC and a gold-standard marker-based motion capture system, Qualisys Track Manager (QTM). Both systems were time synchronised, and the participants performed abduction/adduction of the thumb and flexion/extension movements of all fingers. The LMC and QTM were compared in both static measuring finger segment lengths and dynamic flexion movements of all fingers. A Bland-Altman plot was used to demonstrate the performance of the LMC versus QTM with Pearson's correlation (r) to demonstrate trends in the data. Only the proximal interphalangeal joint (PIP) joint of the middle and ring finger during flexion/extension demonstrated acceptable agreement (r = 0.9062; r = 0.8978), but with a high mean bias. In conclusion, the study shows that currently, the LMC is not suitable to replace gold-standard motion capture systems in clinical settings. Further studies should be conducted to validate the performance of the LMC as it is updated and upgraded.

Recent Insights into the Measurement of Carbon Dioxide Concentrations for Clinical Practice in Respiratory Medicine.

In the field of respiratory clinical practice, the importance of measuring carbon dioxide (CO2) concentrations cannot be overemphasized. Within the body, assessment of the arterial partial pressure of CO2 (PaCO2) has been the gold standard for many decades. Non-invasive assessments are usually predicated on the measurement of CO2 concentrations in the air, usually using an infrared analyzer, and these data are clearly important regarding climate changes as well as regulations of air quality in buildings to ascertain adequate ventilation. Measurements of CO2 production with oxygen consumption yield important indices such as the respiratory quotient and estimates of energy expenditure, which may be used for further investigation in the various fields of metabolism, obesity, sleep disorders, and lifestyle-related issues. Measures of PaCO2 are nowadays performed using the Severinghaus electrode in arterial blood or in arterialized capillary blood, while the same electrode system has been modified to enable relatively accurate non-invasive monitoring of the transcutaneous partial pressure of CO2 (PtcCO2). PtcCO2 monitoring during sleep can be helpful for evaluating sleep apnea syndrome, particularly in children. End-tidal PCO2 is inferior to PtcCO2 as far as accuracy, but it provides breath-by-breath estimates of respiratory gas exchange, while PtcCO2 reflects temporal trends in alveolar ventilation. The frequency of monitoring end-tidal PCO2 has markedly increased in light of its multiple applications (e.g., verify endotracheal intubation, anesthesia or mechanical ventilation, exercise testing, respiratory patterning during sleep, etc.).

Evaluation of time courses of agreement between minutely obtained transcutaneous blood gas data and the gold standard arterial data from spontaneously breathing Asian adults, and various subgroup analyses.

BACKGROUND: Usual clinical practice for arterial blood gas analysis (BGA) in conscious patients involves a one-time arterial puncture to be performed after a resting period of 20-30 min. The aim of this study was to evaluate the use of transcutaneous BGA for estimating this gold standard arterial BGA. METHODS: Spontaneously breathing Asian adults (healthy volunteers and respiratory patients) were enrolled (n = 295). Transcutaneous PO2 (PtcO2) and PCO2 (PtcCO2) were monitored using a transcutaneous monitor (TCM4, Radiometer Medical AsP, Denmark) with sensors placed on the chest, forearm, earlobe or forehead. Transcutaneous BGA at 1-min intervals was compared with arterial BGA at 30 min. Reasonable steps to find severe hypercapnia with PaCO2 > 50 mmHg were evaluated. RESULTS: Sensors on the chest and forearm were equally preferred and used because of small biases (n = 272). The average PCO2 bias was close to 0 mmHg at 4 min, and was almost constant (4-5 mmHg) with PtcCO2 being higher than PaCO2 at ≥8 min. The limit of agreement for PCO2 narrowed over time: ± 13.6 mmHg at 4 min, ± 7.5 mmHg at 12-13 min, and ± 6.3 mmHg at 30 min. The limit of agreement for PO2 also narrowed over time (± 23.1 mmHg at 30 min). Subgroup analyses showed that the PaCO2 and PaO2 levels, gender, and younger age significantly affected the biases. All hypercapnia subjects with PaCO2 > 50 mmHg (n = 13) showed PtcCO2 ≥ 50 mmHg for until 12 min. CONCLUSIONS: Although PtcCO2 is useful, it cannot completely replace PaCO2 because PCO2 occasionally showed large bias. On the other hand, the prediction of PaO2 using PtcO2 was unrealistic in Asian adults. PtcCO2 ≥ 50 mmHg for until 12 min can be used as a screening tool for severe hypercapnia with PaCO2 > 50 mmHg.

[A Light Adaptive Heart Rate Detection Method Based on Webcam].

In order to extract the pulse wave signal of blood volume effectively in the case of uneven light, a light-adaptive heart rate detection method based on webcam was proposed. In this method, adaptive gamma transform is applied to face image sequence to eliminate the influence of illumination. The pulse wave source signal was extracted from the forehead area and the blood volume pulse wave was obtained by wavelet filtering. The heart rate is estimated by Fourier transform analysis. The Bland-Altman analysis indicates that the method used in this paper is in good agreement with the measurement results of the electronic sphygmomanometer, and the adaptive gamma transformation used in this paper eliminates the influence of light interference, and the measurement error of heart rate is significantly reduced, which is completely able to meet the requirements of daily heart rate monitoring.

Intra-individual stability of NREM sleep quantitative EEG measures in obstructive sleep apnea.

Electroencephalography is collected routinely during clinical polysomnography, but is often utilised to simply determine sleep time to calculate apnea-hypopnea indices. Quantitative analysis of these data (quantitative electroencephalogram) may provide trait-like information to predict patient vulnerability to sleepiness. Measurements of trait-like characteristics need to have high test-retest reliability. We aimed to investigate the intra-individual stability of slow-wave (delta power) and spindle frequency (sigma power) activity during non-rapid eye movement sleep in patients with obstructive sleep apnea. We recorded sleep electroencephalograms during two overnight polysomnographic recordings in 61 patients with obstructive sleep apnea (median days between studies 47, inter-quartile range 53). Electroencephalograms recorded at C3-M2 derivation were quantitatively analysed using power spectral analysis following artefact removal. Relative delta (0.5-4.5 Hz) and sigma (12-15 Hz) power during non-rapid eye movement sleep were calculated. Intra-class correlation coefficients and Bland-Altman plots were used to assess agreement between nights. Intra-class correlation coefficients demonstrated good-to-excellent agreement in the delta and sigma frequencies between nights (intra-class correlation coefficients: 0.84, 0.89, respectively). Bland-Altman analysis of delta power showed a mean difference close to zero (-0.4, 95% limits of agreement -9.4, 8.7) and no heteroscedasticity with increasing power. Sigma power demonstrated heteroscedasticity, with reduced stability as sigma power increased. The mean difference of sigma power between nights was close to zero (0.1, 95% limits -1.6, 1.8). We have demonstrated the stability of slow-wave and spindle frequency electroencephalograms during non-rapid eye movement sleep within patients with obstructive sleep apnea. The electroencephalogram profile during non-rapid eye movement sleep may be a useful biomarker for predicting vulnerability to daytime impairment in obstructive sleep apnea and responsiveness to treatment.

Regional deep hyperthermia: quantitative evaluation of predicted and direct measured temperature distributions in patients with high-risk extremity soft-tissue sarcoma.

BACKGROUND: Temperature distributions resulting from hyperthermia treatment of patients with high-risk soft-tissue sarcoma (STS) were quantitatively evaluated and globally compared with thermal simulations performed by a treatment planning system. The aim was to test whether the treatment planning system was able to predict correct temperature distributions. METHODS: Five patients underwent computed tomography (CT) fluoroscopy-guided placement of tumor catheters used for the interstitial temperature measurements. For the simulations, five 3 D patient models were reconstructed by segmenting the patient CT datasets into different tissues. The measured and simulated data were evaluated by calculating the temperature change ( ΔT ), T90, T50, T20, Tmean, Tmin and Tmax, as well as the 90th percentile thermal dose (CEM43T90). In order to measure the agreement between both methods quantitatively, the Bland-Altman analysis was applied. RESULTS: The absolute difference between measured and simulated temperatures were found to be 2°, 6°, 1°, 4°, 5° and 4 °C on average for Tmin, Tmax, T90, T50, T20 and Tmean, respectively. Furthermore, the thermal simulations exhibited relatively higher thermal dose compared to those that were measured. Finally, the results of the Bland-Altman analysis showed that the mean difference between both methods was above 2 °C which is considered to be clinically unacceptable. CONCLUSION: Given the current practical limitations on resolution of calculation grid, tissue properties, and perfusion information, the software SigmaHyperPlan™ is incapable to produce thermal simulations with sufficient correlation to typically heterogeneous tissue temperatures to be useful for clinical treatment planning.