Search

This paper deals with the analysis of the relationship between fetal hemoglobin (HbF) and adult hemoglobin (HbA) in preterm infants as a function of the gestational week and newborn weight based on the available literature. The role of other parameters on the shift and shape of the OHDC curve is also discussed. The function could be useful when dynamic development of OHDC in a neonate occurs in emergencies such as blood transfusions. The main idea is to incorporate the dynamic evolution of the hemoglobin conversion as a mathematical function into existing models of oxygenation in preterm neonates or into automatic feedback control algorithms of oxygenation. This could help further individualize and optimize the oxygenation settings of preterm neonates.

Photoplethysmography signal (PPG) provides information about the cardiovascular, respiratory, or nervous system activity. Recent studies proposed methods of apnea identification from PPG using amplitude or baseline modulation, or area under the curve. We hypothesized that analysis of the dicrotic notch could improve the sensitivity and specificity of apnea detection. We applied four methods to detect apnea from PPG records experimentally obtained from 10 volunteers, where each volunteer simulated three apneic pauses. We adopted the Area under the PPG and Pulse wave amplitude parameters, and we proposed the Dicrotic notch area parameter. For the methods, we determined the delay in apnea detection and the sensitivity and specificity of apnea detection. The average delay in detecting an apneic pause from the PPG using the Dicrotic notch area was 6.1 s. Combining the parameters of the Area under the PPG with the Dicrotic notch area increased the specificity of apnea detection from 73.8% to 80.0%, although sensitivity decreased from 91.1% to 85.6%. The newly proposed parameter Dicrotic notch area showed its potential for automatic apnea detection.

A model of the pulse oximeter, which consists of a transfer function between arterial and peripheral blood oxygen saturation (SpO2) and the noise typical for SpO2 records, is an important part of a mathematical model of oxygenation in neonates that is designed to test and compare different algorithms of oxygen control. The noise level in the SpO2 signal is affected by the averaging time setting of the pulse oximeter. This study aimed to characterize the noise level in the SpO2 signal at the set pulse oximeter averaging times of 2- 4, 8, and 16 seconds. We evaluated SpO2 records of 17 healthy volunteers who underwent a laboratory experiment in which they evoked different types of artifacts. The noise level in the SpO2 signal was characterized by two parameters, the deviation of SpO2 from the true value and the SpO2 time stability, defined as the interval during which the measured SpO2 value remained unchanged. Statistical properties of the noise level for the three averaging times were represented by normalized histograms of both the parameters and varied according to the type of artifact. With motion artifacts, the SpO2 readings deviated from the true value by more than ±2% SpO2 in 10%, 7%, or 5% of the measurements when the set averaging time was 2-4 s, 8 s, or 16 s. The length of the interval over which the SpO2 value remained unchanged was most frequently 2 seconds for all set averaging times. Implementation of the noise characteristics into the computer model of oxygenation in neonates will allow more faithful simulations of the output SpO2 signal that better match clinical observations.

Computer models of neonatal oxygenation could serve as a tool for a comprehensive comparison of closed-loop automated oxygen control systems. The behaviour of such models depends, besides the input data of the inspired fraction of oxygen and the premature infant's breath pattern, on internal parameters of the model. The aim of this study was to perform a sensitivity analysis of a computer model of neonatal oxygen transport to clarify the influence of its internal physiological parameters on the output signal of peripheral oxygen saturation (SpO2). We performed a multi-parameter sensitivity analysis using Monte Carlo simulations for randomly generated values of eight internal parameters. The influence on the model output SpO2 signal was evaluated using five characteristics of the output signal. The relations between the parameters and the output characteristics were displayed using scatter plots and analysed by linear correlation, standardized regression, and partial correlation. The main result of the study is that in our model the oxygen consumption in the tissue and the cardiac output have the greatest influence on the SpO2 drop and minimal SpO2 value during simulated desaturation. The rate of development of desaturation and its duration are most affected by the diffusion resistance of the alveolar-capillary membrane. The results of the sensitivity analysis will help to optimize the performance of the computer model of neonatal oxygen transport.

Maintaining a prescribed peripheral oxygen saturation (SpO2) target during routine care of neonates is challenging and inspired fraction of oxygen (FiO2) titration practices differ among caregivers and centers. Algorithms for automatic feedback control of SpO2 are being developed and tested, that would adapt to the changing neonatal organism and better maintain the required SpO2 target range. While clinical data is necessary to validate differences in the titration strategies, a continuous physiological model of oxygenation in neonates would facilitate baseline testing of different approaches, manual or automated. The objective of our study was to enhance a mathematical model of oxygenation of the neonate and to compare the performance of the model with available clinical data. We have implemented the diffusion resistance into the model as well as a variable oxyhemoglobin dissociation relationship and the bias between arterial and peripheral oxygen saturation. Values of model parameters were scaled to fit preterm infant scenarios. The comparison of the clinical data and computer simulations suggest that the model can reliably simulate episodes of oxygen desaturation and describe the relation between ventilation, FiO2and SpO2. It appears that the model may be an effective tool to test manual and automatic FiO2titration strategies.

The advantages of automatic control of the fraction of inspired oxygen in neonates have been documented in recently published clinical trials. Many control algorithms are available, but their comparison is missing in the literature. A mathematical model of neonatal oxygen transport could be a useful tool to compare and enhance both automatic control algorithms and manual control of fraction of inspired oxygen. Besides other components, the model of neonatal oxygen transport must include a module linking arterial (SaO2) and peripheral (SpO2) oxygen saturation. The pulse oximeter module must reflect issues of SpO2 measurement typical for clinical practice, such as overestimation of SpO2 over SaO2 documented by several studies, or inaccurate pulse oximeter readings due to high noise. The aim of this study was to describe both the bias between SaO2 and SpO2 and the noise, characteristic for continuous SpO2 recording, for a computer model of oxygenation of a premature infant. The SpO2-SaO2 bias, derived from available clinical data, describes a typical deviation of the SpO2 measurement as a function of the true SaO2 value in three different SaO2 intervals. The SpO2 measurement noise was considered as a random process that affects biased SpO2values at each time point with statistical properties estimated from SpO2 continuous recordings of 5 stable newborns. The results of the study will help to adjust a computer model of neonatal oxygenation to the real situations observed in the clinical practice.

Background and Objectives : There is little information on changes in the process and outcomes of intensive tobacco dependence treatment during the COVID-19 pandemic. The following characteristics were evaluated: interest in treatment, the number of face-to-face or telephone follow-ups, the duration of pharmacotherapy use, and the success rate. The aim of our study was to compare the number of patients who entered tobacco dependence treatment programmes and evaluate the one-year success rate in patients three years before and three years after the COVID-19 pandemic. Materials and Methods : A single-site retrospective cohort study using data from patients treated at the Centre for Tobacco Dependence in Prague, Czech Republic, between 2017 and 2022 (n = 2039) was performed. The one-year abstinence rate was validated by measuring carbon monoxide in exhaled air (6 ppm cut-off). Patients were divided into two groups: the group for which treatment was initiated in 2017-2019 (i.e., before the COVID-19 pandemic, BC; n= 1221) and the group for which treatment was initiated in 2020-2022 (i.e., during the COVID-19 pandemic, DC; n = 818). Results : No significant differences in the success rate of tobacco dependence treatment were found between the two groups (BC group, 40.5% (494/1221) vs. DC group, 42.2% (345/818)) ( χ 2 (1, N = 2.039) = 0.6, p = 0.440). Furthermore, differences were not found in sex, education level, age at first cigarette, the duration of pharmacotherapy use, or the number of in-person visits. In contrast, there was an increase in the number of telephone contacts between the groups (18.7% (SD = 17.5%) vs. 32.9% (SD = 18.2%), p < 0.001). Conclusions : The number of patients who started treatment during the COVID-19 pandemic decreased by one-third compared to that during the 3-year period before the pandemic. The overall treatment success rate did not change significantly even with the increase in the number of telephone visits with the therapist.

Although smartwatches are not considered medical devices, experimental validation of their accuracy in detecting hypoxemia is necessary due to their potential use in monitoring conditions manifested by a prolonged decrease in peripheral blood oxygen saturation (SpO 2 ), such as chronic obstructive pulmonary disease, sleep apnea syndrome, and COVID-19, or at high altitudes, e.g., during sport climbing, where the use of finger-sensor-based pulse oximeters may be limited. The aim of this study was to experimentally compare the accuracy of SpO 2 measurement of popular smartwatches with a clinically used pulse oximeter according to the requirements of ISO 80601-2-61. Each of the 18 young and healthy participants underwent the experimental assessment three times in randomized order-wearing Apple Watch 8, Samsung Galaxy Watch 5, or Withings ScanWatch-resulting in 54 individual experimental assessments and complete datasets. The accuracy of the SpO 2 measurements was compared to that of the Radical-7 (Masimo Corporation, Irvine, CA, USA) during short-term hypoxemia induced by consecutive inhalation of three prepared gas mixtures with reduced oxygen concentrations (14%, 12%, and 10%). All three smartwatch models met the maximum acceptable root-mean-square deviation (≤4%) from the reference measurement at both normal oxygen levels and induced desaturation with SpO 2 less than 90%. Apple Watch 8 reached the highest reliability due to its lowest mean bias and root-mean-square deviation, highest Pearson correlation coefficient, and accuracy in detecting hypoxemia. Our findings support the use of smartwatches to reliably detect hypoxemia in situations where the use of standard finger pulse oximeters may be limited.

Objective: Changes in oximeter averaging times have been noted to affect alarm settings. Automated algorithms (A-FiO 2 ) assess FiO 2 faster than oximeter averaging, potentially impacting their effectiveness., Methods: In a single NICU routinely using 15 fabian-PRICO A-FiO 2 systems, neonates were randomly exposed to SpO 2 averaging time settings switched every 12 h among short (2-4 s), medium (10 s), and long (16 s) oximeter averaging times for the entire duration of their A-FiO 2 exposure. Primary endpoints were the percent time in the set SpO 2 target range (dependent on PMA), SpO 2  < 80%, and SpO 2  > 98%, excluding FiO 2  = 0.21., Results: Ten VLBW neonates were enrolled over 11 months. At entry, they were 17 days old (IQR: 14-19), with an adjusted gestational age of 29 weeks (IQR: 27-30). The study included data from 272 days of A-FiO 2 control (34% short, 32% medium, and 34% long). Respiratory support was predominantly non-invasive (53% NCPAP, 40% HFNC, and 6% NIPPV). The aggregate SpO 2 exposure levels were 67% (IQR: 55-82) in the target range, 5.4% (IQR: 2.0-10) with SpO 2  < 80%, and 1.2% (IQR: 0.4-3.1) with SpO 2  > 98%. There were no differences in the target range time between the SpO 2 averaging time settings. There were differences at the SpO 2 extremes ( p  ≤ 0.001). The medium and long averaging were both lower than the short, with the difference larger than predicted. Multivariate analysis revealed that these findings were independent of subject, ventilation mode, target range, and overall stability., Conclusions: This A-FiO 2 algorithm is effective regardless of the SpO 2 averaging time setting. There is an advantage to the longer settings, which suggest an interaction with the controller., Competing Interests: TB receiving consulting fees for Vyaire Medical, none associated with this project. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2023 Janota, Dornakova, Karadyova, Brabec, Rafl-Huttova, Bachman, Rozanek and Rafl.)

Background: There has been a noticeable relative increase in psychiatric comorbidities among smokers as opposed to the general population. This is likely due to comparatively slower decrease in smoking prevalence among individuals with mental health conditions. This study aims to assess the prevalence trend of past or current mental health disorders in individuals seeking specialized smoking cessation assistance., Methods: We conducted a retrospective single-centre observational study to assess the presence of mental disorders such as anxiety, depression, bipolar affective disorder, or schizophrenia in personal history of 6,546 smokers who sought treatment at the Centre for Treatment of Tobacco Dependence in Prague, Czech Republic between 2006 and 2019. The study examined the impact of gender, age, and the effect of successive years on the prevalence of the mental disorders using Poisson distribution regression., Results: In the studied cohort, 1,743 patients (26.6%) reported having one or more mental disorders. Compared to patients without a psychiatric disorder, they exhibited similar levels of carbon monoxide in expired air (mean 17 ppm, SD 11 ppm) and scored one point higher on the Fagerström Test of Cigarette Dependence. Among smokers with a mental disorder, women were more prevalent (62%) than men (38%). The prevalence of mental disorders increased on average by 4% every year, rising from 23% in 2006 to 35% in 2019., Conclusions: Consistent with the observation that the prevalence of smoking among people with any mental disorder is higher and declining at a slower rate than in the general population, there is a steadily increasing percentage of these patients seeking specialized treatment over time. Professionals who offer tobacco dependence treatment should be aware of the upward trend in psychiatric disorders among smokers, as more intensive treatment may be needed. Similarly, psychiatric care should pay attention to smoking of their patients., (© 2023. BioMed Central Ltd., part of Springer Nature.)

Background: Premature newborns often require oxygen support as part of their therapy. Systems for oxygen administration are developed to assure adequate oxygenation of newborns. Several factors were identified in the systems that contribute to the time delay between the change in the set inspiratory oxygen fraction and its actual delivery to tissues. In this study, we aimed to reduce the physical delay in oxygen delivery to newborns., Methods: We developed an O 2 Flush System (O 2 -FS) that brings the source of oxygen as close to a patient as possible to make oxygen available for rapid delivery that compensates for the physical delay in the ventilator circuit. The O 2 -FS system is built around an electromechanical on/off valve. We validated the O 2 -FS concept in experiments with non-invasive Continuous Positive Airways Pressure (CPAP) ventilators., Results: The O 2 -FS accelerated oxygen delivery with all the tested systems and arrangements, typically by 5-15 s. We also observed that the application of supplemental oxygen increased the pressure in the ventilator circuit by 3-4 cmH 2 O which may mitigate the apneic pauses that are common in premature newborns., Conclusions: The O 2 -FS system may work as a universal accessory of the CPAP lung ventilator and shorten the distribution of oxygen to the patient during oxygen desaturation events, possibly eliminating or interrupting apneic pauses in neonates, for whom oxygen therapy is an essential treatment. In clinical practice, the O 2 -FS could help maintain normoxemic saturation values through adequate oxygen dosing in preterm neonates, thus reducing morbidity and mortality., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2023 Tejkl, Kudrna, Rafl and Bachman.)

Objective: We investigated how a commercially available smartwatch that measures peripheral blood oxygen saturation (SpO 2 ) can detect hypoxemia compared to a medical-grade pulse oximeter., Methods: We recruited 24 healthy participants. Each participant wore a smartwatch (Apple Watch Series 6) on the left wrist and a pulse oximeter sensor (Masimo Radical-7) on the left middle finger. The participants breathed via a breathing circuit with a three-way non-rebreathing valve in three phases. First, in the 2-minute initial stabilization phase, the participants inhaled the ambient air. Then in the 5-minute desaturation phase, the participants breathed the oxygen-reduced gas mixture (12% O 2 ), which temporarily reduced their blood oxygen saturation. In the final stabilization phase, the participants inhaled the ambient air again until SpO 2 returned to normal values. Measurements of SpO 2 were taken from the smartwatch and the pulse oximeter simultaneously in 30-s intervals., Results: There were 642 individual pairs of SpO 2 measurements. The bias in SpO 2 between the smartwatch and the oximeter was 0.0% for all the data points. The bias for SpO 2 less than 90% was 1.2%. The differences in individual measurements between the smartwatch and oximeter within 6% SpO 2 can be expected for SpO 2 readings 90%-100% and up to 8% for SpO 2 readings less than 90%., Conclusions: Apple Watch Series 6 can reliably detect states of reduced blood oxygen saturation with SpO 2 below 90% when compared to a medical-grade pulse oximeter. The technology used in this smartwatch is sufficiently advanced for the indicative measurement of SpO 2 outside the clinic., Trial Registration: ClinicalTrials.gov NCT04780724., Competing Interests: The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2022.)

Noninvasive techniques are routinely used for assessment of tissue effects of lung ventilation. However, comprehensive studies of the response time of the methods are scarce. The aim of this study was to compare the response time of noninvasive methods for monitoring of gas exchange to sudden changes in the composition of the inspired gas. A prospective experimental study with 16 healthy volunteers was conducted. A ventilation circuit was designed that enabled a fast change in the composition of the inspiratory gas mixture while allowing spontaneous breathing. The volunteers inhaled a hypoxic mixture, then a hypercapnic mixture, a hyperoxic mixture and finally a 0.3% CO mixture. The parameters with the fastest response to the sudden change of O2 in inhaled gas were peripheral capillary oxygen saturation (SpO2) and regional tissue oxygenation (rSO2). Transcutaneous oxygen partial pressure (tcpO2) had almost the same time of reaction, but its time of relaxation was 2-3 times longer. End-tidal carbon dioxide (EtCO2) response time to change of CO2 concentration in inhaled gas was less than half in comparison with transcutaneous carbon dioxide partial pressure (tcpCO2). All the examined parameters and devices reacted adequately to changes in gas concentration in the inspiratory gas mixture.

Unlabelled: Purpose/Aim : High-frequency oscillatory ventilation (HFOV) is a method of ventilation that theoretically achieves the goals of lung protective ventilation in acute respiratory distress syndrome (ARDS) patients. It is characterized by a rapid delivery of small tidal volumes at high frequencies oscillating around a continuous distending pressure (CDP). Optimization of CDP is not an easy task and it is titrated empirically in the clinical practice. The aim of this study is to investigate whether the level of CDP consistently affects the shape of the partial pressure of oxygen (PaO2) response to stepwise changes in CDP during HFOV of healthy and ARDS-induced pigs., Materials and Methods: We performed two stepwise maneuvers of CDP in 14 pigs: one before and one after the lung lavage, inducing ARDS. For each CDP step performed, we fitted a segment of PaO2 curve with a one-term power model., Results: PaO2 course follows shapes modeled by root, linear, quadratic, and cubic functions for values of PaO2 ≤ 110 mmHg and PaO2 ≤ 200 mmHg, before and after the lung lavage, respectively. PaO2 course follows a shape modeled exclusively by a root function for values of PaO2 > 110 mmHg and PaO2 > 200 mmHg, before and after the lung lavage, respectively. It is not possible to describe a relationship between the shape of the PaO2 course and the values of CDP., Conclusions: The PaO2 curve may give information about the level of recruitment of alveoli, but cannot be used for optimization of CDP level during HFOV in healthy and ARDS lung model pigs.