Search Results (401)

Background/Objectives: Flexible bronchoscopy (FB) enables airway exploration and diagnosis of various respiratory pathologies, but the sedation and instrumentation required during the procedure raise oxygen demand while reducing ventilation, which can lead to hypoxemia. Conventional oxygen therapy (COT) may not adequately prevent desaturations in high-risk groups, as patients with moderate respiratory deficiency. High-flow nasal cannula (HFNC) can deliver heated, humidified oxygen at high flow rates, generating low-level positive airway pressure, improving oxygenation, reducing dead-space, and enhancing procedure tolerance. Prior studies have shown that HFNC can improve gas exchange and reduce desaturations during bronchoscopy. However, evidence remains limited for patients with moderate respiratory deficiency, who are particularly vulnerable. Evaluating the feasibility and safety of HFNC in this population is essential to guide safe procedural practice. Methods: A retrospective observational study including patients undergoing FB with HFNC support between January and May 2025. Inclusion criteria were BMI between 18 and 30; age > 18 years old; moderate respiratory dysfunction, defined by pulse oximetry, Pulmonary Functional Tests (PFTs) and Arterial Blood Gas (ABG) analysis. Exclusion criteria were intolerance/contraindication to HFNC. Procedures were performed under basic monitoring. Primary outcome was occurrence of severe hypoxemia (SpO2 < 90%). Secondary outcomes were needed for rescue maneuvers, interruption for conversion to other ventilatory strategies, and hemodynamic instability. Results: No severe desaturations were recorded, all procedures were completed without rescue maneuvers or other ventilatory strategies, and no hypoxemia occurred. Mean duration of the procedure was 9 min. Vital parameters were maintained within the normal ranges, with a mean SpO₂ during bronchoscopy of 98%. Conclusions: HFNC enables oxygenation and ventilation without adverse events in sedations for FB in patients with moderate respiratory deficiency. Full article

The performance of a building drainage system, “BDS”, is determined by the complexity of internal airflow and pressure dynamics, governed by unsteady wastewater flows from randomly discharging appliances such as WCs, sinks, and baths. Designers attempt to optimise system safety by equalising pressure and incorporating ventilation pipes and active devices such as AAVs and positive pressure reduction devices (PPRDs). However, failures within these systems can lead to foul gases and potentially hazardous microbes entering habitable spaces and posing a risk to public health. This study, for the first time, develops a novel model that simulates the effect of air from the sewer on BDS performance, which describes the correlation between system airflow and air pressure under the influence of air from the sewer. A combination of full-scale laboratory experiments representing a 3-storey building and real-world data from a 32-storey test rig configured as a building demonstrated that sewer air significantly modifies airflow and air pressure within a BDS. These findings are crucial for modern urban environments, where the prevalence of tall buildings amplifies the risks associated with air pressure transients. This work paves the way for updating codes to more effectively address real-world challenges. Full article

In naturally ventilated dairy barns, many questions regarding airflow, indoor air quality, and emissions are still unanswered, often resulting in inaccurate environmental control of the housing. Particularly, limited understanding of the implications of the constantly changing outdoor weather conditions in interaction with the building design and the role of the characteristics of the animals’ movement inside the building enhances uncertainties in the estimation of airflows within and across the barns. Computational fluid dynamics (CFD) have been used in the past to better understand the dynamics of barn climate, but the models are typically too slow to be used for real-time prediction and control. We investigated the effect of animal characteristics (i.e., animal location, orientation, body posture, and dimensions) on the pressure drop in the animal occupied zone considering inlet wind speed from 0.1 m s⁻¹ to 5 m s⁻¹ and wind direction of 0° and 90° in a CFD model. The cow position in general had little impact on the pressure drop at low wind speeds, but became relevant at higher wind speeds. Cows distributed in a more organized alignment showed less airflow resistance, and, therefore, a lower pressure drop and higher air velocities. Moreover, the cow breed affected the pressure drop, with higher withers resulting in a higher pressure drop and air resistance. In contrast, the effects of cow lying–standing ratio on the pressure drop and airflow resistance coefficients were negligible for both investigated wind directions. Our study aims to provide guidance for optimizing parametrizations of the animal occupied zone in order to enhance the speed of simulations without significant loss in model accuracy. In addition, the conclusions drawn from our study may support the adaption of building design and herd management to improve the effectiveness of ventilation concepts of naturally ventilated dairy barns. Full article

High-flow nasal cannula (HFNC) therapy is frequently described as a positive pressure modality, yet this classification lacks mechanistic support. This critical narrative review integrates experimental, computational, and clinical evidence to examine the established physiological mechanisms underlying HFNC, with emphasis on precise terminology. The study clarifies that labeling HFNC as “positive pressure” is conceptually inaccurate, as the system delivers transient, flow-dependent pressures characteristic of open-circuit administration. Evidence is synthesized to quantify the relative contributions of nasopharyngeal dead-space clearance versus emergent pressure generation. Unlike CPAP, HFNC produces pressures ranging from 0.2 to 13.5 cmH₂O, determined by airway geometry, leak magnitude, and mouth position. Fluid dynamic modeling using Bernoulli and Darcy–Weisbach equations demonstrates oscillatory rather than sustained pressures, with magnitudes linked to nasopharyngeal Reynolds numbers (2400–6000) and turbulent energy dissipation (30–60%). Clinical efficacy persists despite variable pressures, reflecting synergistic mechanisms: inspiratory flow matching (40–50% reduction in work of breathing), dead-space clearance (CO₂ reduction, r = −0.77, p < 0.05), emergent pressure effects (10–20%), and thermal humidification (10–20%). Electrical impedance tomography reveals heterogeneous alveolar recruitment, with high-potential (54%) and low-potential (46%) phenotypes. Based on these mechanistic insights, this review proposes the term “emergent hydrodynamic pressure” to accurately describe HFNC’s transient, flow-dependent pressures. This terminology differentiates HFNC from conventional positive pressure systems and aligns language with the principles of fluid dynamics and respiratory physiology. Full article

Background: Marfan syndrome is an autosomal dominant connective tissue disorder that affects multiple organ systems, with cardiovascular complications posing a major risk. With advancements in medical care and the increasing lifespan of patients with Marfan syndrome, the spectrum of medical issues has evolved. This case report highlights the complex anaesthetic management of a patient with Marfan syndrome during elective ventral hernia repair. Case presentation: A 37-year-old male with Marfan syndrome was admitted for elective open ventral hernia repair. Challenges included severe arterial hypertension, prior aortic valve replacement, scoliosis, and an anticipated difficult airway, as the patient presented with restricted mouth opening due to craniofacial abnormalities consistent with difficult laryngoscopy. Preoperative assessments included routine tests, echocardiography and chest X-ray. The anaesthetic management focused on specific patient positioning with head-up tilt, maintenance of haemodynamic stability with the insertion of an arterial line before the induction of anaesthesia and neuromuscular block (NMB) monitoring, followed by titrated doses of all medications. Lung ventilation strategies were specifically adjusted to address the patient’s underlying comorbidities. The patient was extubated and transferred to the recovery unit. The intraoperative and immediate postoperative periods were relatively uneventful. Dyspnea due to external pressure on the abdominal wall caused by a specific binder was treated with the release of pressure. Later postoperative recovery was complicated by hydrothorax and pneumonia, both treated successfully. Conclusions: This case emphasises the importance of multidisciplinary approaches and vigilant monitoring in the management of a patient with Marfan syndrome perioperatively, even for seemingly low-risk operations. Appropriate anaesthetic management helped to avoid major perioperative complications. Full article

Acute respiratory distress syndrome (ARDS) causes heterogeneous injury, with normal, unstable, and edematous tissue distributed throughout the lung. Although positive pressure ventilation initially reduced ARDS-related mortality, it became clear that the ventilator can be a double-edged sword and, if set improperly, can worsen outcomes. This uneven pathology makes the lung vulnerable to secondary ventilator-induced lung injury (VILI). In 2000, evidence showed that lowering tidal volume (V_T) and airway pressure significantly reduced mortality in patients with ARDS, suggesting that this reduction led to less overdistension of healthy lung tissue. Including respiratory system compliance (C_RS) in the calculation. It was shown that low driving pressure (ΔP = V_T/C_RS) was more strongly associated with survival than low V_T alone. This idea was further extended into measuring the mechanical power delivered to the respiratory system: MP_rs = RR × ΔV²∙[1/2∙EL_rs + RR∙(1 + I:E)/60∙I:E∙R_aw] + ΔV∙PEEP, where EL_rs is elastance, I:E is inspiratory:expiratory ratio, R_aw is airway resistance, and RR is respiratory rate. This measure helps identify when the lung is at risk of VILI. However, a recent study found no direct causal link between MP_RS and mortality; rather, it showed that MP_RS, normalized to C_RS or end-expiratory lung volume (EELV), was independently associated with outcomes. This indicates that lung size and underlying pathophysiology—rather than ΔP or MP_RS alone—are critical determinants of VILI risk. Reopening collapsed lung tissue would increase C_RS and decrease E_RS, thereby lowering ΔP or MP_RS at any given V_T, R_aw, PEEP, I:E, or RR setting. Consequently, the focus should shift from simply adjusting the ventilator to normalize C_RS and EELV that reduce ΔP or MP_RS at higher ventilator settings. Full article

Background/Objectives: We investigated multimodal strategies to reduce neonatal ventilator-associated pneumonia (VAP) and antimicrobial use across three periods: period 1 (2014–2017), environmental cleaning with sodium hypochlorite, installation of heat and moisture exchangers, elective high frequency oscillatory ventilation (HFOV) as the primary invasive mode, and nasal HFOV after extubation; period 2 (2018–2020), oral care with maternal milk; and period 3 (2021–2024), nasal synchronized intermittent positive pressure ventilation after extubation. Methods: We conducted a quasi-experimental study of all neonates admitted to a neonatal intensive care unit in Thailand. We compared the trends in VAP and antimicrobial use rates using interrupted time-series analysis with segmented regression. Results: During the 11-year study period, 45.6% of neonates were intubated (2470/5414), and the ventilator utilization ratio was 0.19 (17,820 ventilator days/95,151 patient days). The overall VAP incidence was 4.55 per 1000 ventilator days. The yearly VAP incidence density ratio was significantly lower than in 2014. The baseline trend of VAP incidence and colistin use decreased significantly during period 1; nonetheless, the level and slope did not differ significantly between periods 1, 2, and 3. Conclusions: Tailored implementations, namely environmental decontamination, ventilator circuit care, elective HFOV, and nasal HFOV, reduced VAP and colistin use during period 1. Moreover, additive interventions, including oral care in period 2 and nasal synchronized intermittent positive pressure ventilation in period 3, achieved sustained VAP reduction and limited colistin prescriptions in period 1. Full article

Building drainage systems are essential for protecting occupant health and indoor air quality. While recent studies have focused on high-rise drainage dynamics and riser offset mitigation, ventilation components—particularly appliance vent pipes—remain underexplored. This study employed a full-scale proportional drainage experimental tower to assess appliance vent pipes on horizontal branches as a strategy for water seal protection in dual-riser systems. Maximum drainage capacities were quantified under varying pipe positions and diameters (DN50, DN75, DN100), alongside analyses of pressure transients and water seal losses. Results indicate that appliance vent pipes increase maximum drainage capacity from 6.5 L/s (baseline cast iron dual-riser) to 7.5 L/s, a 1.0 L/s gain, though improvements are modest. Position does not affect capacity (uniformly 7.5 L/s across configurations) but profoundly influences water seal losses: P-type trap placement yields the lowest losses on most floors, combined P-type trap/floor drain placement achieves intermediate values, and floor drain placement the highest. Thus, the P-type trap is optimal. Diameter similarly has no impact on capacity but shows nuanced effects on seals; DN75 minimizes losses on most floors, outperforming DN50 and DN100, indicating that appliance vent pipe design should adopt a height-zoned approach tailored to anticipated drainage loads and pressure characteristics. Appliance vent pipes effectively dampen positive/negative pressure fluctuations, reducing seal depletion and sewer gas risks. These findings guide engineering designs for healthier indoor environments in high-rise buildings. Full article

Background: Early reports highlighted unique features of COVID-19-associated ARDS. The combination of prone position (PP) and positive end-expiratory pressure (PEEP)-induced lung recruitment maneuver (LRM) has demonstrated efficacy in enhancing oxygenation and improving outcomes in patients with ARDS, but it remains unknown whether there is a difference between COVID-19 ARDS and non-COVID-19 ARDS. Method: This study is a secondary analysis of a previously conducted randomized controlled trial. Patients with moderate to severe ARDS were consecutively enrolled during the study period (June–December 2023). After initiation of PP, patients received a PEEP-induced LRM followed by 12 h of daily PP. The interventions were repeated at least three times over the subsequent 3 days. Clinical outcomes, respiratory mechanics, and electrical impedance tomography (EIT) results were evaluated. Results: Twenty-eight patients were included in the final analysis, half of whom were infected with COVID-19 (50%). The PEEP-induced LRM led to greater improvement in oxygenation among COVID-19 ARDS than non-COVID-19 ARDS (∆PaO₂/FiO₂ ratio 90.5 mmHg vs. 65.5 mmHg, p < 0.05). Based on EIT measurement, compared with the non-COVID-19 ARDS group, PEEP-induced LRM resulted in a greater increase in ventilation distribution, mainly in the dorsal regions of interest 4 (ROI 4) ventilation distribution (∆ROI4 4.5% vs. 1.0%, p = 0.01) and in dorsal regional ventilation (∆dorsal regional ventilation 10.0% vs. 5.5%, p = 0.04) in the COVID-19 ARDS group. Conclusions: Compared to typical ARDS, PEEP-induced LRM combined with PP may be more effective in enhancing oxygenation in COVID-19-related ARDS. Full article

Background: In ectopic adrenocorticotropic hormone (ACTH) syndrome, locating the responsible lesion is often challenging. Case Presentation: A 68-year-old woman was transferred to Nara Medical University hospital for a detailed investigation of her ACTH-dependent Cushing’s syndrome. Because of hypercortisolism-induced immunosuppression, she subsequently developed severe Nocardia pneumonia and was forced to temporarily depend on noninvasive positive pressure ventilation (NIPPV). Intravenous antifungal agents and antibiotics were administered, resulting in significant symptomatic improvement. Metyrapone was administered to suppress excessive cortisol. Contrast-enhanced magnetic resonance imaging of the pituitary revealed a 4 mm sized poorly enhanced area, and microadenoma was suspected. Although cavernous venous sampling was indispensable prior to trans-spheroidal surgery (TSS), this examination could not be performed because of the presence of deep vein thrombosis. TSS was performed for both diagnostic and therapeutic purposes, but hypercortisolism did not improve. Moreover, immunohistochemical findings of the specimen revealed nonfunctional pituitary tumor. Methods: We re-evaluated the responsible lesion causing ACTH-dependent Cushing’s syndrome. Fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) revealed weak and abnormal FDG uptake in the right pericardium, but the possibility of nonspecific uptake could not be ruled out. However, gallium-68 1,4,7,10-tetraazacyclododecane-N,N′,N′′,N′′′-tetraacetic-acid-D-Phe¹-Tyr³-octreotide (⁶⁸Ga-DOTATOC)-PET demonstrated the same degree of abnormal uptake; therefore, a functional pulmonary tumor was strongly suspected. Results: Video-Assisted Thoracic Surgery (VATS) was performed, and histopathological findings of the specimen revealed a neuroendocrine tumor with positive ACTH staining. After VATS, ACTH and cortisol levels were normalized. Conclusions: Here, we report a case of ACTH-dependent Cushing’s syndrome caused by a lung neuroendocrine tumor, in which ⁶⁸Ga-DOTATOC PET was helpful in detecting the functional tumors. Full article

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that affects motor neurons; respiratory problems are the leading cause of death and hospital admissions and are secondary to progressive weakness of the respiratory muscles and upper airway. Noninvasive ventilation (NIV) can increase survival, alleviate symptoms, reduce hospital admissions, and improve the quality of life of these patients. The key factor in respiratory management of patients with ALS is achieving effective NIV; ineffective NIV has a negative impact on survival, with a reduction of up to 50% compared to patients with an effective technique. The most common cause of ineffective NIV is air leaks; other causes include upper airway obstruction events, residual hypoventilation, hyperventilation, and upper airway obstruction secondary to an oronasal mask. Regular monitoring of the effectiveness of NIV is essential given its impact on survival; the key tools that detect the main problems are the presence of hypoventilation symptoms, arterial blood gases, nocturnal oximetry and capnography, and built-in ventilator software. Different measures have been proposed to address the ineffectiveness of NIV, such as fitting the mask to reduce air leaks, increasing ventilatory support for residual hypoventilation, decreasing ventilatory support for hyperventilation, or a trial with a nasal mask to address oronasal interface effects. In the case of obstruction, the most common measure is to increase positive expiratory pressure during NIV. These measures enable NIV to be effective in 58% of cases, achieving a survival rate similar to that of patients who have effective NIV from the outset. Full article

Background: Apnea of prematurity affects at least 85% of infants born before 34 weeks’ gestation and represents a significant clinical challenge in neonatal intensive care. Methylxanthines, including caffeine, theophylline, and aminophylline, have emerged as the primary pharmacological intervention for this condition. Objective: To conduct a comprehensive systematic review of the use of methylxanthine in the treatment and prevention of apnea episodes in preterm infants, evaluating efficacy, safety, and long-term outcomes. Methods: We searched multiple databases including PubMed, Embase, Web of Science for randomized controlled trials, retrospective studies, or case–control studies of methylxanthine effects in preterm apnea. Risk of bias was assessed using the Cochrane Risk of Bias tool. Results were summarized narratively and grouped by methylxanthine type, study design, and primary outcomes (reduction in frequency and severity of apnea episodes, success of extubation, risk of bronchopulmonary dysplasia). Results: Twenty-five studies (n = 4599 preterm infants) were included. The landmark Caffeine for Apnea of Prematurity (CAP) trial (n = 2006) demonstrated that caffeine therapy significantly reduced bronchopulmonary dysplasia (36.3% vs. 46.9%, adjusted OR 0.63) and facilitated the earlier discontinuation of positive airway pressure (median 1 week earlier). Studies with a smaller number of cases have consistently demonstrated the efficacy of methylxanthines in reducing the incidence of bronchopulmonary dysplasia and apneic episodes and in supporting successful extubation. Long-term follow-up at 11 years showed improved pulmonary function (FEV₁ z-score −1.00 vs. −1.53). Discussion: Limitations of this review include heterogeneity in outcome definitions, small sample sizes in early studies, and the dominance of evidence from the CAP trial. Methylxanthines, particularly caffeine, are an evidence-based intervention used for apnea of prematurity, with demonstrated benefits that extend beyond reducing the frequency and severity of apnea episodes, including decreasing the risk of bronchopulmonary dysplasia as well as reducing the need for mechanical ventilation. No external funding was received for this review. No registration record exists for this systematic review. Full article

Endotracheal intubation in cats carries risks; supraglottic airway devices (SADs) offer a less invasive alternative. This prospective clinical study evaluated the V-gel^® advanced in cats undergoing ovariohysterectomy, with the primary aim of intra-anaesthetic gas leakage; secondary aims were ease of placement, complications, and the effect of device re-use. Spirometric inspired/expired tidal volumes were recorded under predefined ventilatory settings; leakage was calculated and analysed. Of 52 cats enrolled, 47 were analysed. Leakage occurred in 13% during spontaneous breathing and rose to 41.8% with Continuous Positive Airway Pressure (CPAP) 5 cmH₂O; by contrast, controlled mechanical ventilation showed lower leakage, with the smallest values at Peak Inspiratory Pressure (PIP) of 12 cmH₂O and 16 cmH₂O (2.1% and 6.5%, respectively). Re-used devices leaked less than new ones (p = 0.003). Placement by students was straightforward after adequate depth was achieved. Complications included mild regurgitant material in three cats and pulmonary aspiration in two (one euthanised, one discharged after supportive care). The V-gel^® advanced enabled rapid airway management with leakage influenced by ventilation mode, airway pressure, and device re-use. Findings support cautious use during spontaneous breathing or CPAP, attention to fasting and fresh-gas flows, and further controlled comparisons with prior V-gel^® models and endotracheal intubation. Full article

The study analyzed energy, environmental impact, and costs in intensive broiler production systems in the southeast of the state of Minas Gerais, Brazil, comparing scenarios with and without photovoltaic systems. Four configurations were evaluated, considering different ventilation types (positive and negative pressure) and photovoltaic generation. The Life Cycle Assessment (LCA), with a functional unit of 1 kg of live weight of chicken and a cradle-to-gate approach, indicated that photovoltaic systems reduce between 2.58 t and 4.96 t of CO₂-eq annually, in addition to offering better energy efficiency. Economically, sheds with positive pressure ventilation have the lowest cost–benefit ratios, while the feeding subsystem was the one that contributed the most to global warming, among the environmental impact categories evaluated in the LCA. Photovoltaic systems demonstrated the potential to reduce electricity costs between 19.4% and 26.5% per year. However, coffee husks used as chicken litter accounted for 36.5% of production costs, highlighting the need for more economical alternatives. It was concluded that photovoltaic systems are a viable solution to reduce environmental impacts and increase profitability, reinforcing the importance of resource-use optimization strategies in poultry farming. Full article

Background/Objectives: Closed-loop automated oxygen control (CLAC) systems improve compliance with oxygen saturation targets and other outcomes in preterm ventilated infants. This narrative review aimed to explore the efficacy of CLAC systems in preterm infants receiving non-invasive respiratory support and identify areas that needed further research. Methods: A literature search was conducted using PubMed. The search terms were ‘closed loop’ or ‘automat*’, ‘oxygen’ and ‘neonat*’. Results: Sixteen studies were identified: twelve randomised crossover studies, three randomised controlled trials (RCTs) and a matched-cohort study. Nine studies included only infants receiving non-invasive respiratory support, and the remaining seven incorporated results from infants either on invasive or non-invasive ventilation. Overall, CLAC was associated with an increased percentage of time spent within the target oxygen saturation range and reduced time spent in extremes of oxygenation (SpO₂ < 80% and SpO₂ > 98%) when compared with manual oxygen control. CLAC was applied in infants receiving different modes of non-invasive respiratory support, including continuous positive airway pressure, high and low-flow nasal cannula oxygen. Some of the studies had limited power as they were prematurely stopped due to recruitment or equipment issues. Study periods were mostly less than or equal to 24 h. There were no data on longer-term clinical outcomes, including bronchopulmonary dysplasia, retinopathy of prematurity, necrotising enterocolitis and mortality. Conclusions: CLAC improves the achievement of oxygen saturation targets in preterm infants receiving non-invasive respiratory support. Future research is needed to explore the effect of CLAC on clinical outcomes in this population. Full article