Search Results (485)

Ventilator-associated pneumonia (VAP) is linked to high mortality rates, especially in developing countries. This cross-sectional survey study was conducted across three central hospitals in the Hail region of Saudi Arabia, King Salman Specialist Hospital, Hail General Hospital, and King Khalid Hospital, to assess the knowledge and adherence of intensive care unit (ICU) healthcare practitioners to the ventilator bundle (VB) for VAP prevention. It also looked at the practitioners’ perceived barriers to effective VB deployment. The study (n = 86) revealed significant disparities in VAP prevention knowledge across educational levels regarding the recommended degree of head-of-bed (HOB) elevation (p < 0.001), the use of endotracheal tubes with extra lumens for subglottic drainage (p < 0.001), and the protective effects of 0.12% chlorhexidine gluconate antiseptic oral rinse (p = 0.019). Professional experience significantly influenced knowledge of non-standard VB components (p < 0.001), the recommended frequency of awakening and spontaneous breathing trials (SBTs) (p < 0.001), and knowledge of extra-lumen tubes (p = 0.038) and kinetic beds vs. standard beds (p = 0.005). Significant differences were found between professional categories regarding knowledge of hand hygiene performance (p = 0.032), the correct degree of HOB elevation (p = 0.007), and patient positioning (semi-recumbent vs. supine) (p = 0.023). Years of experience significantly impacted reported compliance with institutional VB (p = 0.013), adherence to oral care protocols (p = 0.035), and the assessment of sedation depth (p = 0.002). While basic measures like HOB elevation practice and DVT prophylaxis showed universal reported compliance (100%), significant performance gaps were identified in more complex tasks, such as interrupting continuous sedative infusions and performing SBTs as recommended (p < 0.001), particularly among novice practitioners. The primary implementation barrier preventing full compliance with the VB was identified as educational deficit, which was prioritized as the most important area for quality improvement, highlighting the need for targeted training for newly hired ICU staff. Full article

Background/Objectives: While packed red blood cell transfusions are commonly administered in anemic neonates, transfusion strategies in preterm infants have been the subject of debate for decades, particularly due to questionable long-term benefits and limited evidence regarding short-term physiological effects. In non-intubated preterm infants, established transfusion thresholds are considered, but individual clinical judgment often plays an important role in the final decision. This study aims to assess the short-term cardiorespiratory effects of red blood cell transfusions in non-intubated very-low-birth-weight (VLBW) infants who were either spontaneously breathing or receiving non-invasive respiratory support. Methods: Retrospective, single-center analysis of 68 VLBW infants (<1500 g) who received 99 red blood cell transfusions between 2019 and 2023. Cardiorespiratory parameters were observed over a 24 h period before and after transfusion. Results: Following transfusion, there was a significant decrease in the frequency of bradycardia events per 24 h (6.51 ± 5.55 to 4.24 ± 3.8; p = 0.004), accompanied by an improvement in the depth of oxygen desaturations (78.7 ± 4.18 to 81.0 ± 3.71; p = 0.001). No significant changes were detected in the desaturation frequency, FiO₂ or heart rate. Conclusions: In clinically stable very-low-birth-weight infants receiving non-invasive ventilatory support, packed red blood cell transfusion is associated with modest, short-term improvements in cardiorespiratory stability. However, these effects are limited in scope. Further research is needed to identify which patient subgroups derive the most significant benefit from these transfusions. Full article

Temporomandibular disorder (TMD) and bruxism affect a significant portion of the adult population, yet why patients with comparable occlusal findings respond so differently to identical interventions remains unexplained by both structural and biopsychosocial frameworks. Traditional occlusal paradigms identified the importance of structural relationships but could not account for clinical variability. Biopsychosocial models advanced understanding of central regulation but lack the physiological specificity needed to connect regulatory state to functional jaw behavior. This paper proposes the Functional Occlusion Regulated Model (FORM), a hierarchical framework integrating central regulatory state, masticatory performance, and structure into a coherent model of jaw function, and identifies its clinical and research implications. Narrative synthesis of the peer-reviewed literature across masticatory physiology, autonomic neuroscience, pain neuroscience, and clinical dentistry was conducted; seventy-two references are cited. Converging evidence supports a three-tier hierarchy in which autonomic and neuromuscular regulatory state is proposed to shape masticatory performance, which influences how structural occlusal conditions are expressed and clinically experienced. FORM generates four testable predictions distinguishing it from existing models, and a preliminary clinical observation documents symptom resolution through regulatory intervention alone without occlusal modification, representing an early published dental observation of this connection. FORM provides a physiologically grounded framework for understanding treatment response variability and proposes central regulatory state as a potentially important upstream influence on functional jaw outcomes. Full article

Precise respiration assessment is crucial for heart rate variability (HRV) interpretation as respiratory components—particularly respiratory sinus arrhythmia (RSA)—provide essential information on vagally mediated regulation. Conventional single-lead electrocardiogram-derived respiration (EDR) methods measure the amplitude modulation of the QRS-waveform caused by respiratory chest movements. This causes a displacement of the electrical heart axis in relation to the ECG lead axis, typically within the 2D frontal plane of the Einthoven electrode montage. Another approach is based on heartbeat acceleration and deceleration during respective inspiration and expiration causing RR interval modulation. However, interval-based methods depend on the complexity of sympathovagal factors that affect RSA. The present feasibility study accounts for the 3D rotational movement of the electrical heart axis during the respiratory cycle and avoids non-respiratory neuromodulatory confounds. The beat-to-beat cardiac rotation was extracted from Frank-XYZ coordinates reconstructed via a four-electrode EASI device. In a pilot study with data from 19 healthy adults performing acoustically paced breathing (6–18 bpm), three surrogates (${\mathrm{RR-Interval}}_{\mathrm{EDR}}$, ${\mathrm{R-Amplitude}}_{\mathrm{EDR}}$, ${\mathrm{Heartmovement}}_{\mathrm{EDR}}$) were compared using a unified Python 3.11.13 pipeline (3D VCG R-peak detection, multivariate Mahalanobis artifact correction, wavelet-based analysis) against a synthetic reference derived from the instructed breathing schedule. The results demonstrated a consistently lower estimation error and higher reference-based signal-to-noise ratio (refSNR), measuring spectral alignment with the paced-breathing trajectory for ${\mathrm{Heartmovement}}_{\mathrm{EDR}}$ and achieving a mean refSNR of 6.01 dB (vs. 4.62 dB for ${\mathrm{RR-Interval}}_{\mathrm{EDR}}$ and 3.20 dB for ${\mathrm{R-Amplitude}}_{\mathrm{EDR}}$) and a mean absolute estimation error of 0.016 Hz (vs. 0.050 Hz and 0.032 Hz, respectively). Notably, ${\mathrm{Heartmovement}}_{\mathrm{EDR}}$ and ${\mathrm{R-Amplitude}}_{\mathrm{EDR}}$ performance slightly improved at higher heart rates, consistent with the interpretation that higher cardiac sampling density benefits spectral resolution for chest movement-based methods, whereas ${\mathrm{RR-Interval}}_{\mathrm{EDR}}$ showed no significant heart rate dependence. Furthermore, ${\mathrm{Heartmovement}}_{\mathrm{EDR}}$ was compared with the EDR results obtained by applying the Kubios-HRV Premium software (version 3.5.0). Kubios-EDR yielded higher precision at elevated breathing frequencies, whereas ${\mathrm{Heartmovement}}_{\mathrm{EDR}}$ outperformed Kubios-EDR at breathing rates below 10 bpm—a range that is particularly relevant for vagally activating slow breathing protocols or treatments. Future work should validate this method using a direct respiration measurement under spontaneous natural breathing conditions. Full article

Background: The methodology of slow-paced breathing (SPB) to optimize cardiorespiratory function requires further refinement. The aim of this study was to identify the methodological ranges of resonance breathing frequencies during SPB in healthy young adults with optimal and suboptimal spirometric indices. Methods: Twenty-eight healthy Indian students living in the Arctic Russian region (age 21–24 years; 20 males, 8 females) underwent spirometry and 2 min HRV recordings at 6 time points: baseline (spontaneous breathing) and SPB periods of 9–13 s with biofeedback. Results: Participants were divided into Group 1 (FEV1 ≥ 80% predicted, n = 13) and Group 2 (FEV1 < 80% predicted, n = 15). At baseline, Group 2 showed reduced overall HRV, lower vagal activity, a higher stress index and lower baroreflex power (by LFmx) vs. Group 1. During SPB, Group 1 exhibited more significant vagal enhancement, peaking at 9–10 s breathing periods. Group 2 showed delayed, wave-like responses with peak effects at 9 s and/or 12–13 s. Conclusions: SPB frequency depends on the level of FEV1: 9–10 s periods in individuals with FEV1 ≥ 80% predicted, and 9 s and/or 12–13 s periods (delayed effect) in those with FEV1 < 80% predicted, which may be due to cardiorespiratory strain under uncomfortable climatic conditions. Full article

Heart rate variability (HRV) is widely used as a non-invasive marker of autonomic regulation and physiological adaptability, with relevance across cardiovascular, metabolic, neuropsychiatric, and stress-related conditions. HRV biofeedback has emerged as a non-pharmacological intervention intended to influence autonomic function through paced breathing, resonance-frequency training, and real-time physiological feedback. Although this approach has shown promise in improving stress regulation, emotional symptoms, autonomic balance, and selected cardiovascular outcomes, its effects are not consistent across individuals or clinical states. The reasons for this variability remain insufficiently conceptualized. In this narrative conceptual review, we propose the concept of autonomic non-responsiveness during HRV biofeedback as a descriptive framework for situations in which expected autonomic engagement is weakened, absent, or fails to translate into meaningful physiological or clinical benefit. We discuss potential contributors to non-response, including reduced autonomic flexibility, impaired baroreflex function, disease burden, fatigue, stress-related overload, dysfunctional breathing, methodological limitations, and cognitive-behavioral constraints. We then consider the clinical implications of recognizing non-response as a potentially informative state rather than a simple negative outcome. Finally, we outline a future research agenda focused on operational definition, candidate biomarkers, temporal characterization, and minimally adaptive closed-loop systems. Full article

Falls among older adults are a major public health concern, yet collecting large-scale real fall data for radar-based detection is ethically and practically difficult. This study presents a controlled simulation-to-real feasibility study for trip-fall detection using continuous-wave (CW) Doppler radar. The method couples a physics-informed kinematic trip-fall model with a CW radar observation model to synthesize I/Q signals and Doppler spectrograms, while domain randomization varies body size, fall direction, initial velocity, sensor placement, aspect angle, amplitude, and noise. Synthetic walking and respiration data were also generated for controlled three-class classification among trip fall, walking, and seated quiet breathing. In Experiment I, the simulated spectrograms reproduced the dominant time–frequency characteristics of measured enacted trip-fall signals acquired with a 24 GHz CW radar; quantitative similarity analysis yielded a mean SSIM of 0.782 and a Doppler-ridge MAE of 24.6 Hz across five fall directions. In Experiment II, a ResNet-18 classifier trained only on simulated spectrograms achieved a macro-F1 score of 0.912 [95% CI: 0.883–0.936] on measured data from ten participants, three start locations, and eight directions. Under the present controlled evaluation, this exceeded the available real-data-trained baseline of 0.748 [95% CI: 0.691–0.805] (paired subject-level permutation test, $p=0.006$). These findings suggest that physics-informed simulation with domain randomization can reduce dependence on real trip-fall samples under limited-data conditions. The results do not establish robustness to other fall morphologies, fall-like activities of daily living, different environments, different radar devices, or embedded deployment. Full article

Background/Objectives: Physiological and psychological health could be altered in modern societies due to stressful environments and activities. A multimodal training based on nutrition, physical activity, breathing and hugging was proposed for improving physiological parameters in a group of women compared to a control group. Methods: 33 women (41 ± 15 years old) were enrolled, divided in two groups, and assessed before and after 6 weeks. Heart rate parameters, superficial adipose tissue (SAT), and trunk rotational range of motion (ROM) were measured. Stroop test and Forward Digit Span Task (FDST) were administered, in order to assess cognitive functions. Results: The trained group showed a significant improvement in the very low-frequency domain of heart rate variability (p = 0.002), a reduction in the high-frequency domain (p = 0.003), an improvement in the number of women with a physiological SAT (p = 0.014), and an improvement in memory (p = 0.005). In the control group, only improvements in the performances of memory (p = 0.029) and attention (p = 0.004) at Stroop test were observed. Conclusions: Changes in cardiac parameters and physiological level of adipose tissue showed significant variations following the multimodal training. For attention and memory, the improvements were observed also in the control group and could be related to a learning effect of the tests. Full article

Efficient segmental pitch control is critical for butterfly swimming propulsion and alignment, yet its role in youth performance remains unclear. This study quantified head, shoulder, and hip pitch kinematics using wearable inertial measurement units (IMUs) in 41 competitive swimmers (9–11 years). Participants performed two maximal 25-m butterfly trials and were classified into faster and slower groups. Pitch angle, velocity, frequency, time, and pitch deviation index were extracted. Between-group differences were assessed using independent t-tests, and associations with performance were examined using Pearson correlations. Faster swimmers exhibited smaller head pitch angles during the Breath phase (p < 0.001, d = −2.01), along with greater shoulder pitch velocities and frequencies (all p < 0.05, d = 0.67–1.07). They also demonstrated shorter pitch times and lower pitch deviation indices (all p < 0.05, d = 0.66–1.92), indicating more efficient and stable movement patterns. In contrast, hip kinematics showed fewer and less consistent differences between groups. Several head and shoulder variables during the Breath phase were moderately correlated with sprint time (r = 0.32–0.43, p < 0.05). These findings suggest that sprint butterfly performance in youth swimmers is primarily associated with more controlled and stable upper-body pitch motion, particularly during breathing. Full article

Limited data are available regarding the physiological profile of youth triathletes. The aim of this study was to characterize the physiological and body composition profile of Hungarian youth triathletes and to examine the relationships between anthropometric characteristics and aerobic performance indicators. Forty-one youth triathletes (20 females and 21 males; age: 15.8 ± 1.7 years), members of the Hungarian national development squad, participated in the study. Anthropometric and body composition parameters were assessed using standardized procedures and multi-frequency bioelectrical impedance analysis. Aerobic performance was evaluated using a graded cardiopulmonary exercise test on a treadmill with breath-by-breath gas analysis. Male athletes demonstrated higher body height, body mass, fat-free mass, and skeletal muscle mass compared with females (p < 0.05). Cardiopulmonary exercise testing revealed high aerobic capacity, with mean VO₂max values of 73.2 ± 5.4 mL·kg⁻¹·min⁻¹ in males and 63.1 ± 5.0 mL·kg⁻¹·min⁻¹ in females. The second ventilatory threshold occurred at approximately 82–86% of VO₂max. Strong positive correlations were observed between anthropometric parameters and absolute oxygen uptake (mL·min⁻¹), particularly for fat-free mass, skeletal muscle mass, and body surface area (r = 0.83–0.95). However, these relationships are influenced by body size and were weaker or inverse when relative oxygen uptake (mL·kg⁻¹·min⁻¹) was considered. Regression analyses further indicated that body composition variables, especially fat-free mass and skeletal muscle mass, were positively associated with aerobic performance, while body fat percentage was not a significant predictor when body size and sex were controlled. These findings are based on cross-sectional associations and should be interpreted as descriptive reference data for this population rather than predictive criteria. The results contribute to the characterization of physiological and anthropometric profiles in youth triathletes and may support future research and athlete monitoring. Full article

Background: Birth asphyxia is a leading cause of neonatal mortality. More than half of these deaths are due to low-quality care. Objectives: To describe the frequency, sequence, timing, and duration of interventions after birth and newborn outcomes. Methods: This prospective observational study in rural Tanzania included newborns ≥28 weeks gestation. Trained research assistants observed and recorded all deliveries and resuscitations 24 h a day, 7 days a week, logging interventions in real time using the Liveborn Observation app. Results: Of 2564 newborns born, 2431 (94.9%) were enrolled in the study. Macerated stillbirth (n = 52), newborns with no parental consent (n = 67) or incomplete Liveborn data (n = 14) were excluded. Additionally, 2193/2431 (90.2%) newborns did not receive bag-mask ventilation (BMV), and 1755/2431 (72.2%) started breathing before 30 s from birth at median (quartiles) 6 (3, 13) s, 438/2431 (18.0%) started breathing beyond 30 s at 49 (38, 67) s. Moreover, 238/2431 (9.8%) received BMV at 82 (54, 120) s after birth, 1/3 within the first min. Finally, 159/238 (66.8%) were suctioned for 26 (17, 40) s. The first suction sequence was initiated at 44 (24, 78) s after birth. In 24/238 (10.1%) newborns, BMV continued for more than 10 min, with an increased risk of dying within 24 h (RR = 4.26, 95% CI; 1.3–10.0, p = 0.016) and seven days (RR = 8.14, 95% CI; 3.5–17.6, p < 0.001) compared to those ventilated for less than 10 min. Conclusions: Almost 10% of newborns received BMV at birth, but only one-third were ventilated within the first recommended minute. Excessive use of suctioning likely delayed the start of BMV, and prolonged ventilation beyond 10 min was associated with higher mortality. Full article

Designing high-speed wide-angle optics for large-format mirrorless cameras presents a fundamental engineering conflict between the short flange back distance and the requirement for high-resolution aberration correction. To address this challenge, this study proposes a compact 18.5 mm F/2.0 lens system utilizing a modified retrofocus architecture equipped with an internal floating-focus mechanism. The design methodology integrates glass-molded aspherical surfaces to suppress high-order aberrations and employs passive athermalization strategies to maintain stability across a temperature range of −30 °C to +70 °C. Performance was rigorously evaluated using numerical simulations in Zemax OpticStudio, alongside comprehensive Monte Carlo tolerance analysis. Simulation results demonstrate exceptional optical performance, with the Modulation Transfer Function (MTF) exceeding 0.5 at a spatial frequency of 100 lp/mm across the field. Furthermore, focus breathing is restricted to less than 1%, and optical distortion is strictly controlled within 2%. The Monte Carlo tolerance analysis predicts a manufacturing yield exceeding 80% under standard industrial precision levels. Ultimately, this work provides a theoretically sound, athermally stable, and highly manufacturable solution suitable for next-generation high-resolution mirrorless sensors. Full article

Background: The breathing cycle consists of abdominal breathing (AB), for which the diaphragm is responsible, and thoracic breathing (TB), generated by the intercostal muscles. Contraction of the two portions of the diaphragm accounts for 80% percent of inspiration. While bilateral diaphragmatic paralysis causes severe shortness of breath, hemidiaphragm paralysis (HDP) gives fewer symptoms at rest, making it difficult to recognize and diagnose. Because this condition is rare, little is known regarding its consequences on breathing efficiency. Hypothesis: Based on previous studies, we hypothesized that body positions substantially affect the efficiency of breathing in a patient with unilateral hemidiaphragm paralysis and the corresponding physiological parameters. Aims: To measure and compare the amplitudes of abdominal and chest movements in different body positions in an individual with HDP and measure parameters indicating breathing efficiency. Patient and Methods: The patient had HDP due to iatrogenic phrenic nerve injury. Changes in the circumference of the abdomen and chest were measured during inhalation and exhalation with respiratory plethysmography belts (placed on standardized reproducible positions on the chest and abdomen) in different body positions: sitting (SI), standing (ST), lying (SU) and prone (PR). Breathing frequency was calculated, and blood oxygen saturation (SpO₂) was measured with a pulse oximeter. Results: The percentage (%) contributions of abdominal breathing were SI: 16.0; ST: 50.3; SU: −53.5; PR: 1.1. A negative sign shows paradoxical breathing. Blood oxygen saturation (SpO₂) in the four positions was SI: 93%; ST: 93%; SU: 82%; and PR: 82%, whereas the respiratory rate (1/min) was SI:19.4; ST: 15.0; SU: 37.5; PR: 35.9. Conclusions: Body position markedly influences the relative contributions of abdominal and thoracic breathing and overall respiratory efficiency in patients with hemidiaphragm paralysis; abdominal breathing in the supine and prone positions is greatly reduced leading to decreased blood oxygen saturation, a compensatory increase in respiratory rate, and severe dyspnea even at rest. Full article

In Coiled Tubing (CT) acoustic telemetry, the reliability of surface signal reception is severely challenged by the “contact dead zone” of traditional probes and complex nonstationary environmental noise. To address these issues, this paper proposes a hardware-software integrated solution for high-fidelity signal extraction. In terms of hardware, a novel pickup probe based on the micro-lever principle is developed. By utilizing a pivoted lever structure with an optimized arm ratio of 2.6 to 1 and a full pressure-balanced mechanism, the design physically overcomes the contact dead zone inherent in traditional pressure-compensating probes and effectively isolates low frequency common-mode interference through a lateral floating architecture. In terms of software, a joint denoising model combining Complete Ensemble Empirical Mode Decomposition with Adaptive Noise and wavelet thresholding is proposed. A cross-correlation coefficient criterion is introduced to adaptively screen intrinsic mode functions and eliminate residual fluid turbulence noise. Field experiments on a 1500 ft full-scale circulation loop demonstrate that the proposed probe improves the detection sensitivity of the radial breathing mode by approximately 20.6 dB compared to the baseline, while effectively eliminating stick-slip friction noise during dynamic tripping. Furthermore, the joint algorithm increases the Signal to noise Ratio by an additional 16.9 dB under typical pumping conditions of 0.5 bpm, with a normalized cross-correlation exceeding 0.96. These results verify that the proposed method effectively solves the bottleneck of weak signal detection in deep wells, providing robust technical support for CT telemetry operations. Full article

This study presents an assessment of forced vibration responses of cracked beam-type aerospace structures using VIbration BehaviouR ANalysis Tool (VIBRANT), a high-fidelity time-marching analysis platform. The methodology captures contact-induced nonlinearities arising when crack surfaces intermittently open and close during vibration, producing time-varying stiffness and damping. Frequency-domain behaviour is extracted from time-domain simulations of beams representing aero-engine blades and wing structures under various crack configurations. Results reveal that a crack-induced nonlinearity is strongly configuration-dependent: only specific combinations of crack depth, position relative to the moment distribution, and excitation amplitude produce detectable nonlinear signatures, whilst other configurations—including cracks representing significant structural compromise—exhibit quasi-linear response that would evade conventional vibration-based detection. The deeper crack configuration activates breathing behaviour at higher forcing levels, leading to rightward resonance frequency shifts and amplitude reductions due to impact and frictional contact damping, whereas the baseline and repositioned crack configurations maintain a quasi-linear response across all forcing levels examined. This configuration-dependent character of the breathing crack nonlinearity—and in particular the conditions under which nonlinear signatures are absent despite active damage—represents a critical finding for structural health monitoring and maintenance planning in aerospace applications. Full article