A prospective observation study of the dynamic monitoring of transcutaneous arterial blood oxygen saturation and carbon dioxide during bronchoscopy.

BACKGROUND AND AIMS: Because bronchoscopy is an invasive procedure, sedatives and analgesics are commonly administered, which may suppress the patient's spontaneous breathing and can lead to hypoventilation and hypoxemia. Few reports exist on the dynamic monitoring of oxygenation and ventilation during bronchoscopy. This study aimed to prospectively monitor and evaluate oxygenation and ventilation during bronchoscopy using transcutaneous arterial blood oxygen saturation and carbon dioxide. METHODS: We included patients who required pathological diagnosis using fluoroscopic bronchoscopy at our hospital between March 2021 and April 2022. Midazolam was intravenously administered to all patients as a sedative during bronchoscopy, and fentanyl was administered in addition to midazolam when necessary. A transcutaneous blood gas monitor was used to measure dynamic changes, including arterial blood partial pressure of carbon dioxide (tcPCO2), transcutaneous arterial blood oxygen saturation (SpO2), pulse rate, and perfusion index during bronchoscopy. Quantitative data of tcPCO2 and SpO2 were presented as mean ± standard deviation (SD) (min-max), while the quantitative data of midazolam plus fentanyl and midazolam alone were compared. Similarly, data on sex, smoking history, and body mass index were compared. Subgroup comparisons of the difference (Δ value) between baseline tcPCO2 at the beginning of bronchoscopy and the maximum value of tcPCO2 during the examination were performed. RESULTS: Of the 117 included cases, consecutive measurements were performed in 113 cases, with a success rate of 96.6%. Transbronchial lung biopsy was performed in 100 cases, whereas transbronchial lung cryobiopsy was performed in 17 cases. Midazolam and fentanyl were used as anesthetics during bronchoscopy in 46 cases, whereas midazolam alone was used in 67 cases. The median Δ value in the midazolam plus fentanyl and midazolam alone groups was 8.10 and 4.00 mmHg, respectively, indicating a significant difference of p < 0.005. The mean ± standard deviation of tcPCO2 in the midazolam plus fentanyl and midazolam alone groups was 44.8 ± 7.83 and 40.6 ± 4.10 mmHg, respectively. The SpO2 in the midazolam plus fentanyl and midazolam alone groups was 94.4 ± 3.37 and 96.2 ± 2.61%, respectively, with a larger SD and greater variability in the midazolam plus fentanyl group. CONCLUSION: A transcutaneous blood gas monitor is non-invasive and can easily measure the dynamic transition of CO2. Furthermore, tcPCO2 can be used to evaluate the ventilatory status during bronchoscopy easily. A transcutaneous blood gas monitor may be useful to observe regarding respiratory depression during bronchoscopy, particularly when analgesics are used.

Acute psycho-physiological responses to submaximal constant-load cycling under intermittent hypoxia-hyperoxia vs. hypoxia-normoxia in young males.

Background: Hypoxia and hyperoxia can affect the acute psycho-physiological response to exercise. Recording various perceptual responses to exercise is of particular importance for investigating behavioral changes to physical activity, given that the perception of exercise-induced pain, discomfort or unpleasure, and a low level of exercise enjoyment are commonly associated with a low adherence to physical activity. Therefore, this study aimed to compare the acute perceptual and physiological responses to aerobic exercise under intermittent hypoxia-hyperoxia (IHHT), hypoxia-normoxia (IHT), and sustained normoxia (NOR) in young, recreational active, healthy males. Methods: Using a randomized, single-blinded, crossover design, 15 males (age: 24.5 ± 4.2 yrs) performed 40 min of submaximal constant-load cycling (at 60% peak oxygen uptake, 80 rpm) under IHHT (5 × 4 min hypoxia and hyperoxia), IHT (5 × 4 min hypoxia and normoxia), and NOR. Inspiratory fraction of oxygen during hypoxia and hyperoxia was set to 14% and 30%, respectively. Heart rate (HR), total hemoglobin (tHb) and muscle oxygen saturation (SmO2) of the right vastus lateralis muscle were continuously recorded during cycling. Participants' peripheral oxygen saturation (SpO2) and perceptual responses (i.e., perceived motor fatigue, effort perception, perceived physical strain, affective valence, arousal, motivation to exercise, and conflict to continue exercise) were surveyed prior, during (every 4 min), and after cycling. Prior to and after exercise, peripheral blood lactate concentration (BLC) was determined. Exercise enjoyment was ascertained after cycling. For statistical analysis, repeated measures analyses of variance were conducted. Results: No differences in the acute perceptual responses were found between conditions (p ≥ 0.059, ηp 2 ≤ 0.18), while the physiological responses differed. Accordingly, SpO2 was higher during the hyperoxic periods during the IHHT compared to the normoxic periods during the IHT (p < 0.001, ηp 2 = 0.91). Moreover, HR (p = 0.005, ηp 2 = 0.33) and BLC (p = 0.033, ηp 2 = 0.28) were higher during IHT compared to NOR. No differences between conditions were found for changes in tHb (p = 0.684, ηp 2 = 0.03) and SmO2 (p = 0.093, ηp 2 = 0.16). Conclusion: IHT was associated with a higher physiological response and metabolic stress, while IHHT did not lead to an increase in HR and BLC compared to NOR. In addition, compared to IHT, IHHT seems to improve reoxygenation indicated by a higher SpO2 during the hyperoxic periods. However, there were no differences in perceptual responses and ratings of exercise enjoyment between conditions. These results suggest that replacing normoxic by hyperoxic reoxygenation-periods during submaximal constant-load cycling under intermittent hypoxia reduced the exercise-related physiological stress but had no effect on perceptual responses and perceived exercise enjoyment in young recreational active healthy males.

Oxygen reserve index vs. peripheral oxygen saturation for the prediction of hypoxemia in morbidly obese patients: a prospective observational study.

BACKGROUND: Pulse oximetry is a standart of anesthesia for perioperative monitoring. Due to the principles of Hb oxygen dissociation curve, peripheral oxygen saturation has an approximate sensitivity and specificity of 90% for the detection of hypoxemia. OBJECTIVES: The primary outcome of the study was to evaluate ORiⓇ as an early parameter to determine hypoxia in morbidly obese patients. The secondary outcome was to compare the effectiveness of ORiⓇ with SpO2 in non-obese patients. DESIGN: Prospective, observational study. SETTING: Department of elective operating room at tertiary hospital. PATIENTS AND METHODS: Observational study included written informed consent from 51 patients with 19 < BMI < 25 kg/m2 and 51 patients with BMI > 40 kg/m2 undergoing an elective surgery requiring tracheal intubation. In addition to standard monitors, an ORi sensor was placed and baseline values were recorded. The patients were preoxygenated until end tidal expiratory oxygen concentration is reached to 90%. After anesthesia induction and tracheal intubation, the breathing circuit was not connected tracheal tube until the SpO2 decreased to 95%. Shapiro-Wilk, Pearson Chi-square, t-test, and Mann Whitney U test were used for the study. MAIN OUTCOME MEASURES: Times of tolerable apnea, ORiⓇ and SpO2 values at the end of preoxygenation, beginning of intubation, beginning of the ORi alarm, when SpO2 reached 95%, and when ORi reaches a plateau. SAMPLE SIZE: 102 patients. RESULTS: The alert period: time to reach ORiⓇ from 0.24 to a value of 95% SpO2 was observed as 32 s in morbidly obese patients and 94 s in patients with a normal body mass index. The SpO2 alert period was determined as time difference between 97% and 95% SpO2. The data were recorded as 15 s and 36 s, respectively. It was observed that tolerable apnea, ORiⓇ, SpO2 and added alert times were longer in patients with normal BMI compared to morbidly obese patients. CONCLUSIONS: As a result, ORiⓇ can provide an early warning to prevent unexpected hypoxia before saturation begins to decrease in morbidly obese patients. LIMITATIONS: Inability to perform arterial blood gas sampling in the time periods when we looked at the parameters to determine the relationship between ORiⓇ and PaO2. GOV IDENTIFIER: NCT05480748 registered 2022-07-29.

Oxygen Saturation Endoscopic Imaging as a Novel Alternative to Assess Tissue Perfusion During Esophagectomy.

BACKGROUND: Assessment of gastric conduit perfusion during esophagectomy is crucial to determine its viability and identify the optimal site for anastomosis. Indocyanine green (ICG) fluorescence imaging is commonly used for this purpose, but it is contraindicated in patients with hypersensitivity to ICG, iodine, or shellfish. Oxygen saturation endoscopic imaging (OXEI) is a newer, non-pharmacologic technique for assessing perfusion. We report our experience with OXEI in 3 esophagectomy patients who had contraindications to ICG. METHODS: All 3 patients underwent robot-assisted esophagectomies. None of the conduits had ischemic areas identified by white light. Using a 5 mm laparoscopic specialized camera (ELUXEO Vision, FUJIFILM Healthcare Americas Corp., USA), OXEI was deployed for intracorporeal assessment of gastric conduit perfusion after pull-up into the chest. Postoperative outcomes including anastomotic leaks and complications were recorded. RESULTS: In two patients, OXEI revealed ischemic zones, which were resected to ensure optimal conduit viability. In the remaining patient, OXEI indicated robust vascularity throughout the conduit. All three patients experienced uneventful postoperative courses and were discharged within 10 days. There were no instances of anastomotic leaks or other major complications. CONCLUSION: In our experience, OXEI is a viable method for intraoperative assessment of gastric conduit perfusion in patients with contraindications to ICG. Prospective studies are needed to validate its efficacy in preventing anastomotic complications and to compare it with other methods of perfusion assessment including gross visual and ICG dye in a larger patient population.

EFFECT OF ENLARGED ADENOIDS AND TONSILS ON BLOOD OXYGEN SATURATION IN AL BAHA, SAUDI ARABIA.

INTRODUCTION: The adenoids and palatine tonsils, part of the lymphoid tissue, act as a first line of defense protecting the lower airways and gastrointestinal tract. Adenotonsillar hypertrophy in children may lead to airway obstruction. This study aims to demonstrate the association between adenotonsillar hypertrophy and decreased blood oxygen saturation. METHODS: A retrospective cohort study was conducted among children aged 7-12 years with adenotonsillar hypertrophy and obstructive symptoms, admitted to King Fahad Hospital and Prince Mishari Hospital, Saudi Arabia, for tonsillectomy between July 2023 and January 2024. Exclusion criteria included respiratory diseases, cardiac disease, nasal polyps, nasal septum deviation, chest wall abnormality, and lower airway diseases. The control group included 56 healthy children. An otolaryngologist determined the severity of airway obstruction using the tonsil size. Oxygen saturation was measured using pulse oximetry. The determinants of oxygen saturation were assessed using multiple linear regression, with significance set at p<0.05. RESULTS: The study included 357 participants, with an even age distribution between 7-9 years (49.6%) and 10-12 years (50.4%), and 52% males. Diagnoses included adenoid hypertrophy (30%), tonsil hypertrophy (35%), both conditions (19%), and the control group (16%). Tonsil sizes ranged from Grade 1 (48%) to Grade 4 (8.4%), with 17% normal. The median oxygen saturation was 96.0% for the adenotonsillar hypertrophy group and 99.0% for the control. Oxygen saturation levels differed significantly across groups (p<0.0001), with lower median saturation in hypertrophy groups than controls. Males had a lower oxygen than females (estimate: -0.338, 95% CI [--0.640, -0.036], p=0.028). Adenoid hypertrophy (estimate: -3.863, 95% CI [-5.241, -2.484], p<0.001), tonsil hypertrophy (estimate: -3.631, 95% CI [-5.053, -2.208], p<0.001) and having both conditions (estimate: -3.777, 95% CI [-5.3.7, -2.247], p<0.001) was associated with lower oxygen saturation. Grade 1 tonsil size was associated with an increase in oxygen saturation (estimate = 2.905, 95% CI [1.616, 4.194], p<0.001). In contrast, Grade 4 tonsil size was linked to lower oxygen saturation (estimate=-4.848, 95% CI [-6.367, -3.329], p<0.001). Grades 2 and 3 were not significantly associated with changes in oxygen saturation. CONCLUSION: Adenotonsillar hypertrophy is significantly associated with decreased blood oxygen saturation and related cardiopulmonary complications in children. Early adenotonsillectomy may be of benefit in preventing these complications and improving oxygen saturation levels.

Morphometric measures and desaturations: Proposal for an index with improved accuracy for obstructive sleep apnea screening.

STUDY OBJECTIVE: To evaluate the sensitivity and specificity of the combined Kushida morphometric model (KMM) and the oxygen desaturation index (ODI) for screening individuals with obstructive sleep apnea. METHODS: Diagnostic test study with adults >18 years, both sexes, polysomnography, body mass index, neck circumference and intraoral measurements. RESULTS: 144 patients were invited; of these, 75 met the exclusion criteria. 55 individuals presented AHI ≥5 ev/h and 14, an AHI <5 ev/h. Three AHI cut-off points were evaluated: AHI ≥5, ≥15, ≥30 ev/h. When adopting the cut-off point of AHI ≥5 ev/h, the KMM showed sensitivity (SE) = 60.0 %, specificity (SP) = 71.4 % and 95 % confidence interval of the area under the curve (95 % CI of AUC) = 0.655; the combination of KMM and ODI (KMM + ODI) revealed SE = 73.0 %, SP = 71.4 % (95 % CI of AUC = 0.779) and the ODI showed SE = 76.4 % and SP = 92.9 % (95 % CI of AUC = 0.815). At the cut-off point of AHI ≥15 ev/h, the KMM presented SE = 64.1 %, SP = 76.7 % (95 % CI of AUC = 0.735); the KMM + ODI showed SE = 82.1 %, SP = 83.3 % (95 % CI of AUC = 0.895); and the ODI presented SE = 76.9 %, SP = 100.0 % (95 % CI of AUC = 0.903). For the cut-off point of AHI ≥30 ev/h, the KMM showed SE = 56.0 %, SP = 77.2 % (95 % CI of AUC = 0.722); the KMM + ODI revealed SE = 92.0 %, SP = 79.5 % (95 % CI of AUC = 0.926); and the ODI showed SE = 92.0 %, SP = 90.9 % (95 % CI of AUC = 0.941). CONCLUSION: The combination of oxygen desaturation index and Kushida morphometric model improved the sensitivity and specificity of this model regardless of obstructive sleep apnea severity suggesting greater effectiveness in risk prediction.

Verbal memory is linked to average oxygen saturation during sleep, not the apnea-hypopnea index nor novel hypoxic load variables.

INTRODUCTION: The apnea-hypopnea index (AHI) is the current diagnostic parameter for diagnosing and estimating the severity of obstructive sleep apnea (OSA). It is, however, poorly associated with the main clinical symptom of OSA, excessive daytime sleepiness, and with the often-seen cognitive decline among OSA patients. To better evaluate OSA severity, novel hypoxic load parameters have been introduced that consider the duration and depth of oxygen saturation drops associated with apneas or hypopneas. The aim of this paper was to compare novel hypoxic load parameters and traditional OSA parameters to verbal memory and executive function in OSA patients. METHOD: A total of 207 adults completed a one-night polysomnography at sleep laboratory and two neuropsychological assessments, the Rey Auditory Verbal Learning Test and Stroop test. RESULTS: Simple linear regression analyses were used to evaluate independent associations between each OSA parameter and cognitive performance. Associations were found between immediate recall and arousal index, hypoxia <90 %, average SpO2 during sleep, and DesSev100+RevSev100. Total recall was associated with all OSA parameters, and no associations were found with the Stroop test. Subsequently, sex, age, and education were included as covariates in multiple linear regression analyses for each OSA parameter and cognitive performance. The main findings of the study were that average SpO2 during sleep was a significant predictor of total recall (p < .007, ß = -.188) with the regression model explaining 21.2 % of performance variation. Average SpO2 during sleep was also a significant predictor of immediate recall (p < .022, ß = -.171) with the regression model explaining 11.4 % of performance variation. Neither traditional OSA parameters nor novel hypoxic load parameters predicted cognitive performance after adjustment for sex, age, and education. CONCLUSION: The findings validate that the AHI is not an effective indicator of cognitive performance in OSA and suggest that average oxygen saturation during sleep may be the strongest PSG predictor of cognitive decline seen in OSA. The results also underline the importance of considering age when choosing neurocognitive tests, the importance of including more than one test for each cognitive domain as most tests are not pure measures of a single cognitive factor, and the importance of including tests that cover all cognitive domains as OSA is likely to have diffuse cognitive effects.

Exploring the impact and influence of melanin on frequency-domain near-infrared spectroscopy measurements.

Significance: Near-infrared spectroscopy (NIRS) is a non-invasive optical method that measures changes in hemoglobin concentration and oxygenation. The measured light intensity is susceptible to reduced signal quality due to the presence of melanin. Aim: We quantify the influence of melanin concentration on NIRS measurements taken with a frequency-domain near-infrared spectroscopy system using 690 and 830 nm. Approach: Using a forehead NIRS probe, we measured 35 healthy participants and investigated the correlation between melanin concentration indices, which were determined using a colorimeter, and several key metrics from the NIRS signal. These metrics include signal-to-noise ratio (SNR), two measurements of oxygen saturation (arterial oxygen saturation, SpO 2 , and tissue oxygen saturation, StO 2 ), and optical properties represented by the absorption coefficient ( µ a ) and the reduced scattering coefficient ( µ s ' ). Results: We found a significant negative correlation between the melanin index and the SNR estimated in oxy-hemoglobin signals ( r s = - 0.489 , p = 0.006 ) and SpO 2 levels ( r s = - 0.413 , p = 0.023 ). However, no significant changes were observed in the optical properties and StO 2 ( r s = - 0.146 , p = 0.44 ). Conclusions: We found that estimated SNR and SpO 2 values show a significant decline and dependence on the melanin index, whereas StO 2 and optical properties do not show any correlation with the melanin index.

The role of endothelial frequency in the cerebral blood flow control during neonatal asphyxia: a retrospective longitudinal study.

BACKGROUND: Cerebral blood flow dynamics can be explored through analysis of endothelial frequencies. Our hypothesis posits a disparity in endothelial activity among neonates with perinatal asphyxia, stratified by the presence or absence of neuronal lesions. METHODS: We conducted a retrospective longitudinal study involving newborns treated with hypothermia for moderate to severe asphyxia. Participants were grouped based on the presence or absence of neuronal damage to investigate temporal endothelial involvement in cerebral blood flow regulation. Regional cerebral oxygen saturation (rScO2) was measured using near-infrared spectroscopy (NIRS), and temporal series were analyzed in the frequency domain, utilizing the original frequency of the INVOS™ device. RESULTS: The study included 88 patients, with 53% (47/88) being male and 33% (29/88) demonstrating brain lesions on magnetic resonance imaging. Among them, 86% (76/88) had a gestational age exceeding 37 weeks according to the Ballard scale, and 81% (71/88) had a birth weight exceeding 2500 g. Cohen's d effect size was calculated to assess differences in endothelial frequency between groups, indicating a small effect size based on cerebral MRI findings (Cohen's d values for Day 2 = 0.2351 and Day 3 = 0.2325). CONCLUSION: NIRS represents a valuable tool for monitoring cerebral autoregulation in neonates affected by perinatal asphyxia, underscoring the utility of assessing endothelial frequency or energy on rScO2 measured by NIRS using the original INVOS™ device frequency.

Mechanical Deviations in Stride Characteristics During Running in the Severe Intensity Domain Are Associated With a Decline in Muscle Oxygenation.

We explored the impact of running in the severe intensity domain on running mechanics and muscle oxygenation in competitive runners by investigating the relationship between mechanical deviations from typical stride characteristics and muscle oxygen saturation (SmO2) in the quadriceps muscle. Sixteen youth competitive runners performed an 8-min exhaustive running test on an outdoor track. Running mechanics were continuously monitored using inertial measurement units. Rectus femoris SmO2 and total hemoglobin (a measure of blood volume) were continuously monitored by near-infrared spectroscopy. One-class support vector machine (OCSVM) modeling was employed for subject-specific analysis of the kinematic data. Statistical analysis included principal component analysis, ANOVA, and correlation analysis. Mechanical deviations from typical stride characteristics increased as the running test progressed. Specifically, the percentage of outliers in the OCSVM model rose gradually from 2.2 ± 0.8% at the start to 43.6 ± 28.2% at the end (p < 0.001, mean ± SD throughout). SmO2 dropped from 74.3 ± 8.4% at baseline to 10.1 ± 6.8% at the end (p < 0.001). A moderate negative correlation (r = -0.61, p = 0.013) was found between the average SmO2 and the percentage of outlier strides during the last 15% of the run. During high-intensity running, alterations in running biomechanics may occur, linked to decreased quadriceps muscle oxygenation. These parameters highlight the potential of using running kinematics and muscle oxygenation in training to optimize performance and reduce injury risks. Our research contributes to understanding biomechanical and physiological responses to endurance running and emphasizes the importance of individualized monitoring.

An efficient model for extracting respiratory and blood oxygen saturation data from photoplethysmogram signals by removing motion artifacts using heuristic-aided ensemble learning model.

Patients with surgical, pulmonary, and cardiac problems, continual monitoring of Oxygen Saturation of a Person (SpO2) and Respiratory Rate (RR) is essential. Similarly, the persons with cardiopulmonary health issues, RR estimation is crucial. The performance of the ventilator assistance and lung medicines are evaluated using SpO2 and RR. For the persons, those who are living alone with respiratory illnesses need a compulsory estimation of RR. In case of serious illness, the RR might face abrupt changes. The immobility of the disturbance and RR makes the RR evaluation from the PhotoPlethysmoGraphic (PPG) signals is a difficult challenge. So, an efficient RR and SpO2 estimation framework from the PPG signal using the deep learning method is developed in this paper. At first, the PPG signal is collected from standard data sources. The collected PPG signals undergo signal pre-processing. The pre-processing procedures include Motion Artifacts (MA) removal and filtering techniques. The pre-processed signals are split into distinct windows. From the split windows of the signals, the spectral features, RR, and Respiratory Peak Variance (RPV) features are extracted. The retrieved features are selected optimally with the help of Advanced Golden Tortoise Beetle Optimizer (AGTBO). The weights are chosen optimally with the same AGTBO. The optimally selected features are fused with the optimal features to get the weighted optimal features. These weighted optimal features are fed into the Ensemble Learning-based RR and SpO2 Estimation Network (ELRR-SpO2EN). The ensemble learning model is developed by combining Multilayer Perceptron (MLP), AdaBoost, and Attention-based Long Short Term Memory (A-LSTM). The performance of the developed RR and SpO2 estimation model is compared with other existing techniques. The experimental analysis results revealed that the proposed AGTBO-ELRR-SpO2EN model attained 96 % accuracy for the second dataset, which is higher than the conventional models such as MLP (90 %), Adaboost (92 %), A-LSTM (92 %), and MLP-ADA-ALSTM (94 %). Thus, it has been confirmed that the designed RR and SpO2 estimation framework from PPG signals is more efficient than the other conventional models.

Validation of an mHealth System for Monitoring Fundamental Physiological Parameters in the Clinical Setting.

The aim of this work was to validate the measurements of three physiological parameters, namely, body temperature, heart rate, and peripheral oxygen saturation, captured with an out-of-the-lab device using measurements taken with clinically proven devices. The out-of-the-lab specialized device was integrated into a customized mHealth application, e-CoVig, developed within the AIM Health project. To perform the analysis, single consecutive measurements of the three vital parameters obtained with e-CoVig and with the standard devices from patients in an intensive care unit were collected, preprocessed, and then analyzed through classical agreement analysis, where we used Lin's concordance coefficient to assess the agreement correlation and Bland-Altman plots with exact confidence intervals for the limits of agreement to analyze the paired data readings. The existence of possible systematic errors was also addressed, where we found the presence of additive errors, which were corrected, and weak proportional biases. We obtained the mean overall agreement between the measurements taken with the novel e-CoVig device and the reference devices for the measured quantities. Although some limitations in this study were encountered, we present more advanced methods for their further assessment.

Influence of an inspiratory muscle fatigue protocol on healthy youths on respiratory muscle strength, vertical jump performance and muscle oxygen saturation: a randomized controlled trial.

BACKGROUND: Inspiratory muscle fatigue has been shown to have effects on limbs blood flow and physical performance. This study aimed to evaluate the influence of an inspiratory muscle fatigue protocol on respiratory muscle strength, vertical jump performance and muscle oxygen saturation in healthy youths. METHODS: A randomized and double-blinded controlled clinical trial, was conducted. Twenty-four participants aged 18-45 years, non-smokers and engaged in sports activity at least three times a week for a minimum of one year were enrolled in this investigation. Participants were randomly assigned to three groups: Inspiratory Muscle Fatigue (IMFG), Activation, and Control. Measurements of vertical jump, diaphragmatic ultrasound, muscle oxygen saturation, and maximum inspiratory pressure were taken at two stages: before the intervention (T1) and immediately after treatment (T2). RESULTS: The IMFG showed lower scores in muscle oxygen saturation and cardiorespiratory variables after undergoing the diaphragmatic fatigue intervention compared to the activation and control groups (p < 0.05). For the vertical jump variables, intragroup differences were found (p < 0.01), but no differences were shown between the three groups (p > 0.05). CONCLUSIONS: Inspiratory muscle fatigue appears to negatively impact vertical jump performance, muscle oxygen saturation and inspiratory muscle strength in healthy youths. TRIAL REGISTRATION: ClinicalTrials.gov ID: NCT06271876. Date of registration 02/21/2024. https://clinicaltrials.gov/study/NCT06271876 .

Leveraging 3D convolutional neural network and 3D visible-near-infrared multimodal imaging for enhanced contactless oximetry.

Significance: Monitoring oxygen saturation ( SpO 2 ) is important in healthcare, especially for diagnosing and managing pulmonary diseases. Non-contact approaches broaden the potential applications of SpO 2 measurement by better hygiene, comfort, and capability for long-term monitoring. However, existing studies often encounter challenges such as lower signal-to-noise ratios and stringent environmental conditions. Aim: We aim to develop and validate a contactless SpO 2 measurement approach using 3D convolutional neural networks (3D CNN) and 3D visible-near-infrared (VIS-NIR) multimodal imaging, to offer a convenient, accurate, and robust alternative for SpO 2 monitoring. Approach: We propose an approach that utilizes a 3D VIS-NIR multimodal camera system to capture facial videos, in which SpO 2 is estimated through 3D CNN by simultaneously extracting spatial and temporal features. Our approach includes registration of multimodal images, tracking of the 3D region of interest, spatial and temporal preprocessing, and 3D CNN-based feature extraction and SpO 2 regression. Results: In a breath-holding experiment involving 23 healthy participants, we obtained multimodal video data with reference SpO 2 values ranging from 80% to 99% measured by pulse oximeter on the fingertip. The approach achieved a mean absolute error (MAE) of 2.31% and a Pearson correlation coefficient of 0.64 in the experiment, demonstrating good agreement with traditional pulse oximetry. The discrepancy of estimated SpO 2 values was within 3% of the reference SpO 2 for ∼ 80 % of all 1-s time points. Besides, in clinical trials involving patients with sleep apnea syndrome, our approach demonstrated robust performance, with an MAE of less than 2% in SpO 2 estimations compared to gold-standard polysomnography. Conclusions: The proposed approach offers a promising alternative for non-contact oxygen saturation measurement with good sensitivity to desaturation, showing potential for applications in clinical settings.

Acute effects of blood flow restricted aerobic exercise in type 2 diabetes mellitus.

BACKGROUND: This study aimed to compare the acute effects of aerobic exercise performed with blood flow restriction (BFR), a novel method to increase exercise gains, with blood free flow (BFF) conditions in type 2 diabetes mellitus (T2DM). METHODS: Fifteen individuals with T2DM performed BFF and BFR (40% of arterial occlusion pressure) cycling exercises 48 hours apart, at equal intensity (45% heart rate reserve) and duration (38 minutes). Systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), blood glucose, heart rate, and muscle oxygen saturation (SmO2) were assessed before-after and during exercise sessions. RESULTS: SBP, DBP, and MAP in the overload phase were higher in the BFR group than in the BFF group (P = .009, 0.031, and 0.013, respectively). Changes in blood pressure (∆SBP and ∆DBP) were similar between the BFF and BFR groups (P > .05), whereas ∆MAP differed (P = .016). Changes in blood glucose levels and heart rates were not significantly different between the groups. Although SmO2baseline was lower in the BFR group (P = .049), SmO2min and SmO2max did not differ significantly between the BFF and BFR groups. CONCLUSION: The similar decrease in blood glucose levels between the groups suggests that BFR exercise is favorable in terms of hypoglycemia. The higher blood pressure observed during the BFR exercise remained within safe limits. These results suggest that people with T2DM can safely perform BFR aerobic exercises; however, further studies are required.

Vital parameter monitoring in harsh environment by the MedSENS in-ear multisensor device.

Accurate assessment of vital parameters is essential for diagnosis and triage of critically ill patients, but not always feasible in out-of-hospital settings due to the lack of suitable devices. We performed an extensive validation of a novel prototype in-ear device, which was proposed for the non-invasive, combined measurement of core body temperature (Tc), oxygen saturation (SpO2), and heart rate (HR) in harsh environments. A pilot study with randomized controlled design was conducted in the terraXcube environmental chamber. Participants were subsequently exposed to three 15 min test sessions at the controlled ambient temperatures of 20 °C, 5 °C, and - 10 °C, in randomized order. Vital parameters measured by the prototype were compared with Tc measurements from commercial esophageal (reference) and tympanic (comparator) probes and SpO2 and HR measurements from a finger pulse-oximeter (reference). Performance was assessed in terms of bias and Lin's correlation coefficient (CCC) with respect to the reference measurements and analyzed with linear mixed models. Twenty-three participants (12 men, mean (SD) age, 35 (9) years) completed the experimental protocol. The mean Tc bias of the prototype ranged between - 0.39 and - 0.80 °C at ambient temperatures of 20 °C and 5 °C, and it reached - 1.38 °C only after 15 min of exposure to - 10 °C. CCC values ranged between 0.07 and 0.25. SpO2 and HR monitoring was feasible, although malfunctioning was observed in one third of the tests. SpO2 and HR bias did not show any significant dependence on environmental conditions, with values ranging from - 1.71 to - 0.52% for SpO2 and 1.12 bpm to 5.30 bpm for HR. High CCC values between 0.81 and 0.97 were observed for HR in all environmental conditions. This novel prototype device for measuring vital parameters in cold environments demonstrated reliability of Tc measurements and feasibility of SpO2 and HR monitoring. Through non-invasive and accurate monitoring of vital parameters from the ear canal our prototype may offer support in triage and treatment of critically ill patients in harsh out-of-hospital conditions.

Validation of multispectral imaging-based tissue oxygen saturation detecting system for wound healing recognition on open wounds.

Significance: The multispectral imaging-based tissue oxygen saturation detecting (TOSD) system offers deeper penetration ( ∼ 2 to 3 mm) and comprehensive tissue oxygen saturation ( StO 2 ) assessment and recognizes the wound healing phase at a low cost and computational requirement. The potential for miniaturization and integration of TOSD into telemedicine platforms could revolutionize wound care in the challenging pandemic era. Aim: We aim to validate TOSD's application in detecting StO 2 by comparing it with wound closure rates and laser speckle contrast imaging (LSCI), demonstrating TOSD's ability to recognize the wound healing process. Approach: Utilizing a murine model, we compared TOSD with digital photography and LSCI for comprehensive wound observation in five mice with 6-mm back wounds. Sequential biochemical analysis of wound discharge was investigated for the translational relevance of TOSD. Results: TOSD demonstrated constant signals on unwounded skin with differential changes on open wounds. Compared with LSCI, TOSD provides indicative recognition of the proliferative phase during wound healing, with a higher correlation coefficient to wound closure rate (TOSD: 0.58; LSCI: 0.44). StO 2 detected by TOSD was further correlated with proliferative phase angiogenesis markers. Conclusions: Our findings suggest TOSD's enhanced utility in wound management protocols, evaluating clinical staging and therapeutic outcomes. By offering a noncontact, convenient monitoring tool, TOSD can be applied to telemedicine, aiming to advance wound care and regeneration, potentially improving patient outcomes and reducing healthcare costs associated with chronic wounds.

Monte Carlo simulation of the effect of melanin concentration on light-tissue interactions for transmittance pulse oximetry measurement.

Significance: Questions about the accuracy of pulse oximeters in measuring arterial oxygen saturation ( SpO 2 ) in individuals with darker skin pigmentation have resurfaced since the COVID-19 pandemic. This requires investigation to improve patient safety, clinical decision making, and research. Aim: We aim to use computational modeling to identify the potential causes of inaccuracy in SpO 2 measurement in individuals with dark skin and suggest practical solutions to minimize bias. Approach: An in silico model of the human finger was developed to explore how changing melanin concentration and arterial oxygen saturation ( SaO 2 ) affect pulse oximeter calibration algorithms using the Monte Carlo (MC) technique. The model generates calibration curves for Fitzpatrick skin types I, IV, and VI and an SaO 2 range between 70% and 100% in transmittance mode. SpO 2 was derived by inputting the computed ratio of ratios for light and dark skin into a widely used calibration algorithm equation to calculate bias ( SpO 2 - SaO 2 ). These were validated against an experimental study to suggest the validity of the Monte Carlo model. Further work included applying different multiplication factors to adjust the moderate and dark skin calibration curves relative to light skin. Results: Moderate and dark skin calibration curve equations were different from light skin, suggesting that a single algorithm may not be suitable for all skin types due to the varying behavior of light in different epidermal melanin concentrations, especially at 660 nm. The ratio between the mean bias in White and Black subjects in the cohort study was 6.6 and 5.47 for light and dark skin, respectively, from the Monte Carlo model. A linear multiplication factor of 1.23 and exponential factor of 1.8 were applied to moderate and dark skin calibration curves, resulting in similar alignment. Conclusions: This study underpins the careful re-assessment of pulse oximeter designs to minimize bias in SpO 2 measurements across diverse populations.

Effect of high-flow nasal and buccal oxygenation on safe apnea time in children with open mouth: A randomized controlled trial.

BACKGROUND: High-flow nasal oxygenation is reported to prolong duration of apnea while maintaining adequate oxygen saturation with the mouth closed. Also, buccal oxygenation is known to have similar effects in obese adults. We compared the effect of these two methods on prolongation of acceptable apnea time in pediatric patients with their mouth open. METHODS: Thirty-eight patients, aged 0-10 years were randomly allocated to either the high-flow nasal oxygenation group (n = 17) or the buccal oxygenation group (n = 21). After induction of anesthesia including neuromuscular blockade, manual ventilation was initiated until the expiratory oxygen concentration reached 90%. Subsequently, ventilation was paused, and the patient's head was extended, and mouth was opened. The HFNO group received 2 L·min-1·kg-1 of oxygen, and the BO group received 0.5 L·min-1·kg-1 of oxygen. We set a target apnea time according to previous literature. When the apnea time reached the target, we defined the case as "success" in prolongation of safe apnea time and resumed ventilation. When the pulse oximetry decreased to 92% before the target apnea time, it was recorded as "failure" and rescue ventilation was given. RESULTS: The success rate of safe apnea prolongation was 100% in the high-flow nasal oxygenation group compared to 76% in the buccal oxygenation group (p = .04). Oxygen reserve index, end-tidal or transcutaneous carbon dioxide partial pressure, and pulse oximetry did not differ between groups. CONCLUSION: High-flow nasal oxygenation is effective in maintaining appropriate arterial oxygen saturation during apnea even in children with their mouth open and is superior to buccal oxygenation. Buccal oxygenation may be a good alternative when high-flow nasal oxygenation is not available.