Journal of Clinical Monitoring and Computing

Objective. This study evaluates a method for calibrating mainstream CO2 analysers in which CO2 partial pressure (P CO2) is calculated as a function of the outputs of CO2 and O2 analysers. Methods. Three mass flow controllers were used to generate 25 different reference mixtures of O2, N2 and CO2. Reference gas mixtures were combinations of P CO2 = 2, 4, 6, 8, 10 kPa and O2 partial pressure (P O2) = 10, 20, 40, 60, 80 kPa (balance N2). CO2 and O2 analyser data were fitted by a calibration equation which took into account the effects of oxygen partial pressure and nonlinearity of the CO2 analyser. The calibration coefficients were tested in a separate validation data set with a variety of combinations of CO2 and O2. Results. Our new calibration method yields a standard deviation of CO2 measurement error that is significantly lower than a CO2-only calibration method in the validation data set (0.54% versus 2.72%, P < 0.05). P CO2 measurement errors produced by the single gas calibration equation are significantly correlated with P O2 in both the calibration (R = −0.9906, P < 0.05) and validation data sets (R = −0.9642, P < 0.05), but the errors given by our new calibration equation are independent of P O2 (R = −0.0364, NS, and R = −0.0305, NS, for calibration and validation data sets respectively). Calibration with only CO2 cannot eliminate the error related to the collision broadening effect of O2, which in our CO2 analyser is approximately a 1% underestimation of P CO2 for every 10 kPa (75 mmHg) increase in P O2. Conclusions. This study shows that non-dispersive infrared CO2 analyser readings can be substantially affected by background oxygen. This effect can be corrected for by calibrating the CO2 analyser with gases containing known proportions of both CO2 and O2.

Đối với nhiều bệnh nhân mắc Bệnh Phổi Tắc Nghẽn Mạn Tính (COPD), độ bão hòa oxy động mạch trong khi được nhận Liệu pháp Oxy Dài Hạn (LTOT) thường giảm xuống dưới ngưỡng chấp nhận (SpO2 < 90%) trong suốt thời gian dài khi thực hiện các hoạt động hàng ngày. Sử dụng một bộ điều khiển vòng kín, chúng tôi đã đánh giá một phương pháp mô phỏng để tự động điều chỉnh lưu lượng oxy theo nhu cầu oxy đo được. Chế độ điều khiển vòng kín được triển khai trong một mô phỏng trên Simulink™. Phản hồi từ một máy đo oxy xung đã được sử dụng để duy trì mục tiêu SpO2 là 91% bằng cách thay đổi lưu lượng oxy cung cấp cho bệnh nhân. Bộ điều khiển đã được đánh giá bằng cách sử dụng một mô hình để xấp xỉ phản ứng độ bão hòa oxy động mạch của bệnh nhân, bao gồm các sự kiện thiếu oxy từ các rối loạn nhân tạo cũng như dữ liệu oximetry đã ghi nhận từ bệnh nhân. Bộ điều khiển mô phỏng tạo ra sự cải thiện về độ bão hòa oxy động mạch trong suốt một loạt các tần số rối loạn khác nhau. Nó triệt tiêu các rối loạn có chu kỳ lớn hơn vài phút hơn -10 dB. Khi được đánh giá bằng các bản ghi oximetry của bệnh nhân, bộ điều khiển trung bình đã giảm 76% thời gian độ bão hòa máu động mạch dưới ngưỡng. Với cùng một thể tích oxy, bộ điều khiển vòng kín cũng mang lại sự cải thiện 63% so với LTOT lưu lượng cố định. Các phát hiện từ mô phỏng cho thấy sự phù hợp tối ưu giữa cung và cầu oxy, duy trì SpO2 trên ngưỡng nhằm cải thiện hiệu quả trị liệu so với LTOT tiêu chuẩn.

Well-designed randomized controlled trials (RCTs) are considered to represent a high level of evidence and influence medical decision-making in evidence-based medicine. When biases occur in study design, processing, and reporting of RCTs, however, it is difficult to interpret results and judge the impact of interventions. Accordingly, we evaluate the quality of RCT reporting published in the Journal of Clinical Monitoring and Computing (JCMC) using three assessment tools. Reporting quality of RCTs published in the JCMC was evaluated through December 31, 2020, using Jadad and van Tulder scales and the Cochrane Collaboration’s risk of bias tool (CCRBT). Stepwise regression analysis was performed to identify factors associated with reporting quality. Database searches confirmed 132 RCTs in 1,507 original articles. The numbers of RCTs meeting criteria for high reporting quality were 97 (73.5%) using the Jadad scale, 99 (75.0%) using the van Tulder scale, and 19 (14.4%) with the CCRBT. Jadad scores [median score (interquartile range) = 3.0 (2.0–5.0), coefficients (95% CI) = 0.08 (0.04, 0.11), p < 0.001], van Tulder scores [median score (interquartile range) = 7.0 (5.0–8.75), coefficients (95% CI) = 0.15 (0.11, 0.20), p < 0.001], and CCRBT assessment [coefficients (95% CI) = 0.04 (0.02, 0.06), p < 0.001] increased significantly with publication year. The median score (interquartile range) of the last 5 years were 4.0 (3.0–5.0) in Jadad scores, and 8.0 (6.0–9.0) in van Tulder scores. Only 33.3% and 37.1% of articles described detailed blinding and allocation methods, respectively. Reporting quality increased over time, with consistently high reporting quality in recently published JCMC RCTs.

Clinicians strive to maintain normothermia, which requires measurement of core-body temperature and may necessitate active warming of patients. Monitoring temperature currently requires invasive probes. This work investigates a novel foam-based flexible sensor worn behind the ear for the measurement of core body temperature. This observational study uses the device prototype and clinical data to compare three methods for calculating the temperature from this sensor: a basic heat-flow model, a new dynamic model that addresses changing surrounding temperatures and one that combines the dynamic model with a correction for adhesive quality. Clinical validation was performed with 21 surgical patients (average length of surgery 4.4 h) using an esophageal temperature probe as reference. The operative period was divided into four segments: normal periods (with stable surrounding temperatures), surrounding temperatures increasing due to the use of the Bair Hugger™, stable periods during Bair Hugger™ use and surrounding temperatures decreasing due to its removal. The error bias and limits of agreement over these segments were on average of − 0.05 ± 0.28 °C (95% limits of agreement) overall. The dynamic model outperformed the simple heat-flow model for periods of surrounding temperature changes (12.7% of total time) while it had a similar, high, performance for the temperature-stable periods. The results suggest that our proposed topical sensor can replace invasive core temp sensors and provide a means of consistently measuring core body temperature despite surrounding temperature shifts.

To compare and assess silicone membrane-based sub-Tenon’s block (STB) simulator and animal eye model (goat’s eye) for practicing STB in terms of anatomical similarity and feel of texture of eye layers. The study included 34 participants (26 learners and 8 consultants) from tertiary ophthalmic centres. The participants were divided into groups A and B. Group A performed STB on the goat’s eyes before using the silicone membrane simulator. Group B performed STB on the simulator and further proceeded to the goat’s eye. Participants had to rate the anatomical similarity and feel of the texture for the simulator model on a scale of 0–10 and share their preference between the two models. In group A, the scores given to the simulator model and the feel of texture of layers were 8.05 ± 0.88 and 7.97 ± 1.07, respectively, and the scores given to the animal model and the feel of texture of layers were 8.11 ± 0.97 and 8.21 ± 0.88, respectively. Group B participants scored the simulator model and feel of texture of layers with 8.13 ± 0.95 and 8.25 ± 0.99, respectively. Overall, 89% participants preferred the simulator; the reasons included ease of usage, helpful warning system, absence of biological waste, and facility for repeatable training. The study validated anatomical accuracy, preference, and ability of usage of the STB simulator. For broader usage, further study involving higher number of participants is recommended.

Objective.Until now, the knowledge of combining anestheticsto obtain an adequate level of anesthesia and to economize wakeup timehas been empirical and difficult to represent in quantitative models.Since there is no reason to expect that the effect of non-opioid andopioid anesthetics can be modeled in a simple linear manner, the use ofa new computational approach with Bayesian belief network software isdemonstrated. Methods.A data set from a pharmacodynamic studywas used where remifentanil was randomly given in three fixed targetconcentrations (2, 4, and 8 ng/ml) to 62 subjects. Target concentrationsof propofol were controlled according to the closed-loop system feedbackof the auditory evoked potential index to render modeling unbiased bythe level of anesthesia. Time to open eyes was measured to representwakeup time after surgery. The NETICA version 1.37 software was used ona personal computer for network building, validation, and prediction.Results.After the learning phase, the network was used togenerate a series of random cases whose probability distribution matchesthat of the compiled network. The sampling algorithms used are precise,so that the frequencies of the simulated cases will exactly approach theprobabilities of the network and that of the data learned. Thegraphical display of the predicted wakeup time shows less variabilitybut a more complex interaction pattern than with the unadjusted originaldata. Conclusions.Model building and evaluation with Bayesiannetworks does not depend on underlying linear relationships. Bayesianrelationships represent true features of the represented data sample.Data may be sparse, uncertain, stochastic, or imprecise. Multipleplatform software that is easy to use is increasingly available.Bayesian networks promise to be versatile tools for building valid,nonlinear, predictive instruments to further gain insight into thecomplex interaction of anesthetics.

The photoplethysmography (PPG) signals detected by transesophageal oximetry sensor toward aorta arch (AA), descending aorta (DA), and left ventricle (LV) under the guidance of transesophageal echocardiography (TEE) were investigated, and the effects of filter application on PPG signals were evaluated. Eleven cardiac surgical patients were involved. After anesthesia was induced, the TEE probe with a modified pulse oximetry sensor was inserted. Under the guidance of TEE, the AA PPG, DA PPG and LV PPG were detected respectively when ventilator was on and off. The mean alternating current (AC) amplitudes and direct current (DC) values of original and filtered PPG signals were measured. The ratio of AC and DC value (AC/DC) and ventilation-induced AC variations were calculated. Satisfactory PPG waveforms were obtained in all patients under the guidance of TEE. The AC amplitude in LV PPG was significant larger than in AA and DA PPG, and both AC/DC and ventilation-induced AC variation in LV PPG were significantly higher than in AA PPG or DA PPG either. There were no significant differences of AC amplitude between filtered and ventilation off PPG signals. The AC amplitudes and AC/DC toward LV are significantly higher than transesophageal oximeter toward AA or DA, and the effect of mechanical ventilation on transesophageal PPG can be obviously reduced by filtering techniques.